JP2006243453A - Screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen which has a high gain in a wide angle of view, has a wide angle of view without making a structure complex, and is inexpensive and excellent in lightweight property, durability and shape holding property and can be used for various screen. <P>SOLUTION: The screen is constituted by using a void fiber which is constituted in such a manner that two mutually immiscible components of polymers A and B are blended and has voids inside, wherein 300 or more voids exist in the fiber cross section perpendicular to the fiber axis direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflective screen that forms an image by reflecting an image projected from a projector such as a video, projector, or projector onto the projector side. More specifically, the present invention relates to a screen using fibers having a large number of voids of a specific size, and has a high gain and a small change in a wide field of view.

  Said void fiber has the inclination structure of the space | gap where the magnitude | size of a void becomes large in steps from a fiber outer layer part to a center part. The presence of the air gap in the fiber in an inclined manner increases the light diffusing ability of the fiber, resulting in a wide viewing angle screen.

  And when adopting a fiber whose cross-sectional shape is irregular cross section, the inclination tendency of the voids in the fiber becomes large, so it not only has a high gain at a wide viewing angle, but also the light projected by the irregular cross section is moderately recursive (projection The reflected light is reflected in the direction of the projector), so that the screen has a high gain at a specific viewing angle and little change.

  Since the void fiber itself has high light reflectivity and light diffusibility, the screen of the present invention does not require a complicated multilayer structure as in the prior art, and the screen structure can be simplified. It provides a screen that is excellent in light weight at low cost.

  In recent years, large-screen LCDs and plasma TVs, or video projectors have become widespread as home video forming devices for the purpose of enjoying powerful images in the home with large screens, high image quality, space saving, and energy saving. . In particular, the image forming system using a video projector has been attracting attention as a next-generation image forming system because it can be easily enlarged by adjusting the screen size for projecting the image and the distance from the projector. Yes.

  Screens for projecting images from such image projectors are roughly divided into two types depending on the direction in which the images are projected. One is a reflective screen where the image projected on the projector is reflected by the screen, and an observer on the projector side can see the image, and the other is the image projected by the projector transmitted through the screen. This is a transmissive screen that allows an observer on the opposite side of the projector to see the image. The screen of the present invention relates to the latter reflective screen.

  As a characteristic of the screen, it is desired to obtain a bright (high gain) image with a wide viewing angle. In order to obtain a wide viewing angle, it is necessary not only to reflect the projected light in one direction but also to diffuse it in all directions. However, in this case, light reflection also occurs in the direction where there is no observer, so that the gain tends to be low, and the video tends to be dark. On the other hand, if the reflected light is given recursion (light is reflected in the direction of the projector), a bright image is observed from an observer in the normal direction of the screen surface, but the viewing angle of the screen is narrowed. Tend to.

  In this way, viewing angle and gain are contradictory properties, and a PVC (polyvinyl chloride) layer, glass bead layer, metal deposition layer, etc. are bonded to a fiber substrate (glass fiber), and the surface is embossed. Proposals have been made to develop light diffusivity and recursion according to the purpose by forming a complex multilayer structure by forming irregularities due to the above. However, since such a multi-layer screen has a multi-layer structure, the weight per unit area increases, and the screen becomes heavier when the screen is enlarged. For this reason, the installation method, carrying out, etc. are restricted, and it is inferior to lightness and storage property. Moreover, in order to maintain the reflection characteristics of the screen, it is always necessary to keep the reflection surface clean. However, when cleaning is performed, there is a problem that the reflection characteristics are easily changed due to the glass beads falling off the reflection surface. . Moreover, the cost was high and the versatility was low.

  From the above, it is desired that the reflection characteristics of the screen can be controlled without using a complicated structure and that a bright image can be seen with a wide viewing angle. For this reason, a proposal has been made for a desired screen by imparting characteristics to the cross-sectional shape of the fiber or the woven or knitted structure, diffusing the incident light without transmitting it, and appropriately recurring the incident light. The present situation is that the reflection characteristics of the screen are still insufficient.

  For example, a proposal has been made to provide anisotropy in the viewing angle in the machine direction and the transverse direction by using thin wires having an elliptical or elliptical cross section for warp and weft and providing a light reflecting layer on one side of the fabric. (See Patent Document 1). However, the fibers used in the woven fabric of this technique are ordinary solid fibers, and light is transmitted only by the fibers. For this reason, it is indispensable to provide a light reflection layer on one side of the fabric by metal vapor deposition, which is also inferior in lightness and storage. Certainly, the gain in a specific viewing angle range can be increased, and a bright image can be obtained from the observer in the center of the screen, but the incident light is not diffused because of the use of ordinary solid fibers. The change in brightness according to the angle direction for observing the screen is large (the change in gain due to the viewing angle is large), and only a narrow viewing angle can be obtained.

  It has also been proposed to use a fabric with a specific weave structure with low regularity as the screen base fabric to obtain a screen in which the reflection direction of light is random on the fiber surface and the gain change due to the viewing angle is small. Patent Document 2). Certainly, because the weave structure is irregular, light is diffused on the reflective surface, and a screen with a small gain change depending on the viewing angle can be obtained, but since a normal synthetic fiber is used, the light transmission loss is large, and the screen The whole image was dark. In order to reduce transmission loss, it has been shown that fibers containing a large amount of fine white powder such as titanium oxide are used inside the fibers, but titanium oxide not only reflects incident light but also absorbs light. Therefore, when it is contained in a large amount, the gain becomes low, and it tends to be a dark image on the entire screen.

In order to impart lightness to the fiber, the present inventors already have a sea-island polyester composite fiber composed of polyester and a thermoplastic polymer (excluding polyester) having no maleimide structure, and at least part of the sea-island composite interface has voids. The polyester composite fiber which is excellent in the lightweight property whose fiber has an apparent specific gravity of 1.2 or less is proposed (see Patent Document 3). This technology retains excellent lightness due to the presence of a large number of fine voids inside the fiber, and because of the fineness of the voids, it has excellent fiber properties and obtains lightweight fibers suitable for clothing and industrial applications. be able to. As a result of further study on this technology, the present inventors have a function of reflecting light without transmitting light incident on the fiber because the fiber has a void inside the fiber. From the fact that it is fine, it has a function of diffusing light, and thus it has been found that the above-mentioned fibers are optimal as a base fabric material for a screen.
Japanese Patent Laid-Open No. 4-1739 (claims, left column on page 2) JP 2003-207852 A (Claims, paragraph [0008]) JP 2004-183196 A (Claims)

  An object of the present invention is to provide a screen that has not only a complex multilayer structure but also a wide viewing angle and a high gain and a bright image, as well as low cost, light weight, portability, durability, and shape retention. It is to provide.

In order to solve the above problems, the present invention adopts the following configuration. That is,
[1] A fiber in which two components of polymer A and polymer B that are incompatible with each other are blended, and has a void inside the fiber, and the void is 300 in the fiber cross section perpendicular to the fiber axis direction. A screen comprising the above-described void fiber.

  [2] The screen according to [1] above, wherein void fibers having an average diameter of voids present in the fiber cross section of 0.01 μm or more and 1 μm or less are used.

  [3] In the fiber cross section, when the fiber is divided into an outer layer part and an inner layer part by a cross-sectional shape similar to the fiber cross-sectional shape sharing the center of the fiber cross-section and having a diameter of ½, a void existing in the outer layer part The above-mentioned [1] or [2], wherein void fibers having an inclined structure of voids satisfying the following formula (1) are used: the ratio of the average diameter d1 of the voids to the average diameter d2 of voids existing in the inner layer portion As described in the screen.

d2 / d1 ≧ 1.3 (1)
[4] The screen according to any one of [1] to [3], wherein a void fiber having a cross-sectional shape of an irregular shape is used.

  The screen of the present invention has a large number of voids, and by using void fibers having fine voids, the light incident on the reflection surface of the screen is not reflected but reflected. Since the light is diffused, the gain is high over a wide viewing angle, and the gain change with the viewing angle is also small. In addition, the above characteristics are further improved when void fibers having a large inclination tendency of voids are used. And if the fiber cross section is an irregular cross section and the void fiber with a high inclination tendency of the gap is formed by positively forming the gap inclination structure, the incident light is diffused and reflected by the inclined structure in the highly developed gap. Since the incident light is recursively reflected by the cross section, the gain in the specific viewing angle region is high, and the gain change due to the viewing angle is small. For this reason, it has excellent reflection characteristics without a complex multilayer structure, and the specific gravity of the void fiber used is smaller than the specific gravity of the solid fiber, so it can be reduced in weight as a large screen, and installation and transportation work can be simplified. Since the manufacturing process can be simplified and the incidental equipment such as a hoisting motor can be downsized, the manufacturing cost can be greatly reduced. Since a large number of voids exist discontinuously in the longitudinal direction of the fiber, deformation of the voids can be suppressed even if bending or wear occurs, and the void structure does not change due to screen cleaning, folding, or winding. For this reason, it can be set as the screen excellent in practical durability and portability suitably used by various types, such as a fixed type, a winding type, and a folding type. From the above, it can be suitably used not only for theater screenings, home theaters, presentations, games, and amusement parks but also for mobiles that are carried and projected when going out.

  It is important that the screen in the present invention uses void fibers. The void fiber will be described in detail later, but it may be used for a part or all of the screen of the present invention. In order to make use of the reflection characteristics of the void fiber, it is preferable to use the void fiber as at least a part of the reflection surface of the screen.

  The fibers used in the screen of the present invention have a thin and long shape, and may be long fibers (filaments) or short fibers (staples) generally referred to, or for electric flocking processing and the like. The short fiber used, ie, a pile, may be used, and there is no particular limitation as long as it is recognized as having these fiber shapes. Moreover, there is no restriction | limiting in particular also about the form of fiber, such as raw yarn, twisted yarn, and processed yarn. A filament is preferable because it is easy to obtain a screen having high form retention or durability when external force is applied. When it is a filament, it may be a multifilament or a monofilament.

  The form of the void fiber used in the screen as a fiber structure is not particularly limited, and can be used as a conventionally known form such as a woven fabric, a knitted fabric, a nonwoven fabric, or a pile-like material, and is appropriately selected according to the intended use. However, a woven fabric is preferable because a high-density fiber structure is preferable in that the gain of the screen becomes higher. When a woven fabric is used, separate void fibers having different void structures can be used for the warp and the weft, and the reflection characteristics in the vertical and horizontal directions of the screen can be made anisotropic. Further, when the screen is required to be stretchable, it is preferable to use a knitted fabric or a non-woven fabric.

  As a woven structure of the woven fabric, for example, as a single woven fabric, a plain weave such as broad, voile, lone, gingham, tropical, taffeta, shantung and desin, twill weave such as denim, surge and gabardine, satin weave such as satin and doskin, Nanako weaves such as baskets, Panama, mats, hopsacks, oxfords, woven fabrics such as grosgrains, ottomans, hair cords, steep slashes such as French twills, herringbones, broken twills, slow slashes, Yamagata slashes, broken slashes , Jumping slashes, curved slashes, ornamental slashes, irregular sashes, layered sachets, spread sachets, day and night shimeko, honeycombs, hacks, pears, niagaras, etc. As a double woven fabric that has become a single woven fabric, warp double weaves such as picket and puffer weave, double wefts such as Bedford cord, air-weaving, It is like weave background double such weave is appropriately selected depending on the intended use.

Examples of pile fabrics include weft pile weaves such as benji and corten, warp pile weaves such as towels, velvet and velvet, etc. Are appropriately selected depending on the application and purpose.
The knitting structure of the knitted fabric includes, for example, flat knitting such as tengu and single, rib knitting such as rubber knitting and milling, pearl knitting such as lynx, kanoko, satin, accordion knitting, small pattern, lace knitting, and back hair Weft knitting such as knitting, one-sided knitting, two-sided knitting, ripple, Milan rib, double picket, etc., or warp knitting such as tricot, russell, miranese, etc., which are appropriately selected according to the use and purpose.

  Examples of the structure of the nonwoven fabric include nonwoven fabrics formed by methods such as chemical bond method, thermal bond method, needle punch method, water jet punch (spun lace) method, stitch bond method, felt method, etc. It is appropriately selected according to the purpose.

  Moreover, as long as the effect of the present invention is not hindered, it may be subjected to processing such as conventional scouring, dyeing, heat setting, etc., and physical processing such as glazing press, embossing press, compact processing, flexible processing, heat setting, etc. And chemical processing such as bonding processing, laminating processing, coating processing, vapor deposition processing, antifouling processing, water repellent processing, antistatic processing, flameproof processing, insectproof processing, sanitary processing, foam resin processing, and other micro processing Application processing such as wave application, ultrasonic application, far-infrared application, ultraviolet application, and low-temperature plasma application may be performed. However, in the case of a foldable screen, care should be taken because cracks or creases in the coating layer may cause gain in viewing the image and hinder the effects of the invention.

The screen of the present invention can obtain a target screen having a high gain such that incident light is not transmitted to the rear of the screen. Therefore, the basis weight of the fiber structure forming the reflective surface of the screen is preferably high, preferably 100 g / m ² or more, more preferably 150 g / m ² or more, and 200 g / m ² or more. Even more preferred. However, if the basis weight is excessively high, the compression between the yarns may increase, resulting in problems such as collapse of the voids inside the fibers or deterioration of the process passability, so 1000 g / m ² or less is preferable.

  The thickness of the screen of the present invention may be appropriately selected according to the intended use. However, if the thickness is excessively thin, it may be difficult to keep the reflective surface of the screen flat. For this reason, the thickness of the screen is preferably 0.1 mm or more, preferably 0.2 mm or more, and more preferably 0.3 mm or more. The upper limit is not particularly limited, but is preferably 5 mm or less. The thickness of the screen may be adjusted by the fineness of the fiber or by laminating a plurality of the fiber structures.

  The screen of the present invention preferably has a high screen gain in that a brighter image can be viewed. Gain is the numerical value of the reflection characteristics (brightness at each angle) inherent to the screen, and it gives a constant light to the perfect diffuser (showing almost constant reflectivity in the vertical and horizontal directions). It is defined as the ratio of the luminance measured by applying the light to the screen under the same condition and scanning the same arc from the center point.

The gain is determined from the relationship between the luminance (candela / m ² ) measured while changing the angle between the luminance meter and the light source, and the illuminance (lux) of the light source by installing a light source in the ray direction from the center of gravity of the reflective surface of the screen. It is calculated by the following equation (2). The larger the gain, the brighter the screen.

Gain = [luminance (candela / m ² ) / illuminance (lux)] × π (2)
The illuminance (lux) of the light source is calculated by the following equation (3) from the relationship between the light output (lumen) of the light source and the projection area (m ² ).

Illuminance (lux) = light output (lumen) / projection area (m ² ) (3)
The peak value (peak gain) of the gain is preferably 0.5 or more, more preferably 0.6 or more, and 0.8 or more in that a more powerful image can be displayed. Even more preferred is 1.0 or more. The upper limit of the peak gain may be appropriately selected according to the intended use. However, if it is too large, a difference in brightness occurs depending on the viewing angle, which may not be suitable for practical use. For this reason, the peak gain is preferably 10 or less, preferably 9 or less, and more preferably 8 or less.

  An angle at which the gain peak value is halved is called a half-value angle. The larger this value is, the wider the viewing angle is, and it is more suitable for viewing images. Since the screen of the present invention has a function of reflecting and diffusing incident light without transmitting it by using void fibers, the peak gain is high, the half-value angle is large, or there is no half-value angle. A screen with a large viewing angle is obtained. The half-value angle is preferably 30 ° or more, more preferably 40 ° or more, and particularly preferably 50 ° or more in that the screen can be viewed from multiple directions. When used for viewing from a certain direction, the half-value angle is preferably 80 ° or less, preferably 70 ° or less, and 60 ° or less in that the gain at the special angle can be increased. Even more preferred.

  The above-mentioned peak gain and half-value angle are related to the diameter of voids present in the void fibers used in the screen, the number of voids, the inclination tendency of the voids, the cross-sectional shape of the fibers, and the refractive index difference between polymer A and polymer B. Light incident on the screen is divided into reflected light and transmitted light at the interface between the fiber surface layer and the outside of the fiber, the interface between the polymer A and the inside of the gap, the interface between the polymer B and the inside of the gap, or the interface between the polymer A and the polymer B. The transmitted light is refracted corresponding to the difference in refractive index at the interface. Incident light is diffused and reflected by repeating such a complicated reflection phenomenon inside the fiber. In addition, since there are many voids in the void fiber, incident light does not transmit to the opposite side of the reflecting surface, resulting in a screen having a high gain with a wide viewing angle and a small gain change depending on the viewing angle. .

  Hereinafter, the void fiber used for the screen of the present invention will be described in detail.

  It is important that the void fiber used in the screen of the present invention is a fiber obtained by blending two components of polymer A and polymer B. The blend fiber means a fiber formed from a blend composition in which the polymer A and the polymer B are kneaded at any stage before melt spinning is completed by various methods as described later, and the fiber axis direction In the cross section of the fiber orthogonal to, a sea-island structure is formed in which polymer A forms the sea and polymer B forms the island. Moreover, the polymer B which is an island exists in a streak shape in the fiber axis direction, and the streaks are discontinuous having an appropriate length. Therefore, the composite interface between polymer A and polymer B in the fiber becomes very large, and when it becomes a void fiber, discontinuous voids are generated with respect to the fiber axis, and the fiber has many fine voids. Polymer B exists in this void. Since the polymer B is contained inside the fiber, the light is appropriately refracted by the difference in the refractive index of the elements forming the interface and does not strengthen, so that image defects such as hot spots do not occur. A hot spot is a video failure that causes a luminance peak on the screen.

  The void fiber used in the screen of the present invention has 300 or more voids present in the fiber cross section perpendicular to the fiber axis direction. By using a void fiber having a large number of voids having different diameters, a screen having a high light gain and a high peak gain and a large half-value angle can be obtained for the first time. The number of voids present in the fiber cross section is preferably 500 or more, more preferably 1,000 or more, and even more preferably 10,000 or more. The upper limit of the number of voids is not particularly limited, but is preferably about 1,000,000 or less. The number of voids can be confirmed by the method of Example I below.

  The void fiber used in the screen of the present invention does not transmit light incident on the screen, the voids are not easily crushed, and the characteristics of the screen are easily maintained. It is preferable that the thickness exceeds 0.01 μm. The average diameter of the air gap is preferably 0.03 μm or more, and more preferably 0.05 μm or more, from the viewpoint that transmission of incident light is further suppressed and a screen with high gain is obtained. However, if the voids are too large, the absolute number of voids present inside the fiber decreases, and the area of the interface that diffuses incident light decreases, so that the light diffusing ability tends to decrease. For this reason, the average diameter of the voids is preferably 1 μm or less, more preferably 0.8 μm or less, and particularly preferably 0.5 μm or less. The average diameter of the voids is defined by I.D. It can be calculated by this method.

  The void ratio indicating the void ratio of the void fiber used in the screen of the present invention is preferably 15% or more, more preferably 25% or more from the viewpoint that the screen is more lightweight. Is more preferable. Here, the porosity is defined as F.F. It is computable by measuring by the method of.

  The void fiber used for the screen of the present invention preferably has discontinuous voids in the fiber axis direction. This is preferable because the light diffusing ability of the screen increases and the half-value angle increases. In addition, since the gap is discontinuous in the fiber axis direction, the gap is easily crushed by external force, and the cross-sectional shape of the fiber and the structure of the gap are not easily changed by bending or abrasion, and various characteristics of the screen are not impaired in actual use. . The discontinuity of the voids can be confirmed by a single fiber cross-sectional photograph and a longitudinal cross-sectional photograph observed by the method I defined in the examples described later.

  It is preferable that the void fiber used for the screen of the present invention has a void inclined structure in which the void diameter gradually increases from the fiber surface layer portion to the fiber central portion in the fiber cross section. And the larger the ratio of the size of the air gap near the fiber surface layer and the size of the air gap near the fiber center, that is, the greater the inclination tendency, the wider the incident light in the fiber corresponds to the air gap distribution. Therefore, the half-value angle is large because it is diffused and the gain is also high because it is difficult to transmit incident light.

  And in the fiber cross-section, when the fiber cross-sectional shape is similar to the fiber cross-sectional shape sharing the center of the fiber cross-section and is divided into the outer layer portion and the inner layer portion of the fiber by the cross-sectional shape having a diameter of 1/2, the average of the voids existing in the outer layer portion A screen using void fibers in which d2 / d1 which is a ratio of the diameter d1 to the average diameter d2 of the voids existing in the inner layer portion is 1.30 or more is preferable because the half-value angle is large and the gain is also high. d1 and d2 are defined as I.D. It calculates by image analysis using the fiber cross-sectional photograph obtained by the method. It is preferable that d2 / d1 ≧ 1.5, more preferably d2 / d1 ≧ 1.8, and d2 / d1 ≧ 2 in that the half-value angle of the screen is larger and the screen has a higher gain. More preferably, it is 0.0. The upper limit of d2 / d1 is not particularly limited, but is preferably about 100 or less.

  When the void fiber of the present invention has an irregular cross section in the fiber cross section, it is preferable because the inclination tendency of the voids is easily developed. Here, the fiber cross section is a cross section perpendicular to the fiber axis direction, that is, a fiber cross section perpendicular to the fiber axis direction, and the cross-sectional shape is a modified cross-section fiber, so that the light reflected on the fiber surface is again, It is easy to take advantage of the effect of entering the inside of the fiber and the space inside the fiber diffusing light and suppressing the transmission of light, resulting in a screen with a large half-value angle and high gain. It is also possible to control the characteristics of the screen by appropriately selecting the shape of the irregular cross section.

  For example, when the observer is present in a certain viewing angle region and the purpose is to obtain a bright image in the viewing angle region, a symmetrical shape such as a flat shape, an elliptical shape, a multileaf shape, or a polygonal shape is used. It is preferable to adopt a certain cross-section, maintain a suitable recursive capability, and obtain a screen with a high gain in a specific viewing angle region. Of course, the half-value angle tends to decrease as much as the recursive ability is maintained, but the half-angle decrease is minimized because it has a tendency to incline the highly developed voids inside the fiber. In particular, when increasing the gain in a narrow area, it is preferable to adopt a flat, elliptical, trilobal, or triangular cross section. When it is desired to increase the gain in a relatively wide specific area, the number of leaves It is preferable to adopt a cross section of a multi-leaf type of 5 or more and a polygon type of 5 or more. On the other hand, when obtaining a screen aimed at observing from a different direction with a large number of people, it is preferable to adopt a non-symmetrical cross-sectional shape and to have a high light diffusivity and a large half-value angle.

  When the void fiber used for the screen of the present invention has an irregular cross section, it is preferable that the degree of irregularity is higher because the fiber has a higher inclination tendency inside the fiber. Therefore, the degree of deformity is preferably 1.20 or more, more preferably 1.3 or more, still more preferably 1.4 or more, and particularly preferably 1.5 or more. The upper limit is not particularly limited, but it is preferably 7.0 or less, and preferably 5.0 or less in that the cross-sectional shape and the durability of the voids are improved, and as a result, the durability of the reflection characteristics of the screen is improved. More preferably, it is more preferably 3.0 or less, and particularly preferably 2.0 or less.

  The degree of irregularity in the present invention is defined as the ratio (D1 / D2) of the diameter D1 of the circumscribed circle and the diameter D2 of the inscribed circle in the single fiber cross section. When it is judged that the irregular cross section generally retains line symmetry and point symmetry, the inscribed circle is a circle inscribed in the curved line that forms the profile of the irregular cross section fiber in the single fiber cross section, and the circumscribed circle is a single fiber. It is a circle that circumscribes a curve that defines the profile of the irregular cross-section fiber in the cross section. For example, the degree of irregularity of the three-leaf shaped irregular cross-section fiber shown in FIG. 1 is calculated using the diameter D1 of the circumscribed circle 1 and the diameter D2 of the inscribed circle 2. In addition, when it is determined that the irregular cross section has a shape that does not retain line symmetry or point symmetry at all, it is inscribed at least at two points with the curve that forms the profile of the irregular cross section fiber, and exists only inside the fiber. A circle having the maximum radius that can be taken in a range in which the circumference of the inscribed circle does not intersect with the curved line forming the profile of the irregular cross-section fiber is defined as the inscribed circle. The circumscribed circle circumscribes at least two points in the curve showing the profile of the irregular cross-section fiber, exists only outside the cross-section of the single fiber, and is the smallest possible in the range where the circumference of the circumscribed circle and the profile of the irregular cross-section fiber do not intersect A circle having a radius is defined as a circumscribed circle.

  When the void fiber used for the screen of the present invention has an irregular cross section, the inclined structure of the voids preferably has anisotropy. It is preferable to have an inclined structure having anisotropy in the cross section of the fiber because light incident from multiple directions on the fiber is reflected by a wide variety of gap distributions, and the light diffusing ability of the screen is increased. The inclined structure having anisotropy in the present invention means an inclined structure of voids existing in the direction of the line segment (11) connecting the contact point of the circumscribed circle and the center of gravity in the cross section of the single fiber, and the contact point and center of gravity of the inscribed circle. It means that the inclined structure of the voids existing in the direction of the line segment (12) connecting the two is different. When the number of voids intersecting or in contact with l1 (nl1) and the average diameter of the voids (dl1) are different from the number of voids intersecting or in contact with l2 (nl2) and the average diameter of the voids (dl2), It is judged that the inclined structure of the gap has anisotropy. It is preferable that nl1 / nl2 ≧ 1.1, and more preferably nl1 / nl2 ≧ 1.3 in that the light diffusing ability of the screen becomes higher and the screen has a larger half-value angle. The upper limit of nl1 / nl2 is not particularly limited, but is preferably about 20 or less. For the same reason, the relationship between dl1 and dl2 is preferably dl1 / dl2 ≧ 1.1, and more preferably dl1 / dl2 ≧ 1.3. The upper limit of dl1 / dl2 is not particularly limited, but is preferably about 20 or less.

  The void fiber used in the screen of the present invention preferably has a skin layer without voids on the fiber surface. By having the skin layer, the fiber is not scraped by bending or abrasion, and the durability of the void structure existing inside the fiber is further enhanced. Further, since the strength of the fiber is improved, it can be suitably used as a large screen. If the thickness of the skin layer is too thick, the volume in which voids are formed inside the fiber decreases, and as a result, the light transmitted through the screen increases, resulting in a screen with a low gain. The thickness of the skin layer is preferably 1/5 or less, more preferably 1/10 or less, and 1/15 or less of the fiber diameter D (diameter D1 of the circumscribed circle in the case of an irregular cross section). Even more preferred. Moreover, since the effect of a skin layer will be lose | eliminated when too thin, it is preferable that it is 1/1000 or more of D1. This skin layer can be formed at the same time as the voids described later are formed. Therefore, this skin layer is composed of a blend polymer of polymer A and polymer B.

  The polymer A forming the void fiber used in the screen of the present invention is not particularly limited as long as it has fiber forming ability, and as a polymer used for general purposes, a polyester-based polymer, a polyamide-based polymer, a polyimide-based polymer is used. Examples include polymers, polyolefin polymers, other vinyl polymers, fluorine polymers, cellulose polymers, silicone polymers, elastomers, and various other engineering plastics.

  More specifically, for example, in polyolefin polymers and other vinyl polymers synthesized by a mechanism in which a monomer having a vinyl group such as radical polymerization, anion polymerization, or cation polymerization is generated by an addition polymerization reaction, polyethylene, polypropylene , Polybutylene, polymethylpentene, polystyrene, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene chloride, poly (vinylidene chloride), etc. For example, it may be a polymer obtained by homopolymerization such as polyethylene alone or polypropylene alone, or a copolymer polymer formed by conducting a polymerization reaction in the presence of a plurality of monomers. Well, for example, styrene and Doing polymerization in methyl methacrylate presence poly - but polymers copolymerized as (styrene methacrylate) is produced, it may be a polymer which is such a copolymer.

  Further, for example, polyamide polymers formed by the reaction of carboxylic acid or carboxylic acid chloride and amine can be mentioned. Specifically, nylon 6, nylon 7, nylon 9, nylon 11, nylon 12, nylon 6,6. Nylon 4,6, Nylon 6,9, Nylon 6,12, Nylon 5,7, Nylon 5,6 and the like, and other aromatics, aliphatics and alicyclics as long as they do not impair the gist of the present invention An aromatic dicarboxylic acid and an aromatic, aliphatic or alicyclic diamine component, or one compound such as aromatic, aliphatic or alicyclic used alone as an aminocarboxylic acid compound having both a carboxylic acid and an amino group Alternatively, it may be a polyamide polymer in which the third and fourth copolymer components are copolymerized.

  Moreover, for example, a polyester polymer formed by esterification reaction of carboxylic acid and alcohol can be mentioned. Specifically, the polyester-based polymer referred to in the present invention is not particularly limited, and examples thereof include polymers formed from ester bonds of dicarboxylic acid compounds and diol compounds. Examples thereof include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycyclohexanedimethanol terephthalate. Although not particularly limited, the polyester polymer formed from the ester bond of the dicarboxylic acid compound and the diol compound may be copolymerized with other components within a range not impairing the gist of the present invention. As the dicarboxylic acid compound of the copolymer component, for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylethane dicarboxylic acid, Adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, azelaic acid, dodecanedioic acid, hexahydroterephthalic acid, etc. Aromatic, aliphatic, alicyclic dicarboxylic acids and their alkyl, alkoxy, allyl, aryl, amino, imino, halide and other derivatives, adducts, structural isomers, optical isomers can be mentioned. Among the acid compounds, one kind may be used alone, or two or more kinds may be used in combination as long as the gist of the invention is not impaired.

  Examples of the copolymer component include diol compounds such as ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, hydroquinone, resorcin, dihydroxybiphenyl, naphthalenediol, anthracene. Aromatic, aliphatic and alicyclic diol compounds such as diol, phenanthrenediol, 2,2-bis (4-hydroxyphenyl) propane, 4,4′-dihydroxydiphenyl ether, bisphenol S, and their alkyl, alkoxy, allyl, Derivatives, adducts, structural isomers, and optical isomers such as aryl, amino, imino, and halide can be listed. One of these diol compounds can be used alone. Also it may be, or in a range that does not impair the gist of the invention may be used in combination of two or more.

  Examples of the copolymer component include a compound having a hydroxyl group and a carboxylic acid in one compound, that is, a hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include lactic acid, 3-hydroxypropionate, and 3-hydroxybutyrate. Aromatic, aliphatic and alicyclic diol compounds such as acrylate, 3-hydroxybutyrate valerate, hydroxybenzoic acid, hydroxynaphthoic acid, hydroxyanthracenecarboxylic acid, hydroxyphenanthrenecarboxylic acid, (hydroxyphenyl) vinylcarboxylic acid, and their Derivatives, adducts, structural isomers and optical isomers such as alkyl, alkoxy, allyl, aryl, amino, imino, and halide can be mentioned, and one of these hydroxycarboxylic acids may be used alone. Or invention It may be used in combination of two or more in a range that does not impair the gist.

  Further, the polyester polymer may be a polymer in which one compound such as aromatic, aliphatic, alicyclic, etc. is mainly composed of a hydroxycarboxylic acid compound having both a carboxylic acid and a hydroxyl group as a main repeating unit. For example, polylactic acid, poly (3-hydroxypropionate), poly (3-hydroxybutyrate), poly (3-hydroxybutyrate valerate), etc. Poly (hydroxycarboxylic acid) can be mentioned, and besides these poly (hydroxycarboxylic acids), aromatic, aliphatic, alicyclic dicarboxylic acids, or aromatics can be used without departing from the spirit of the present invention. , Aliphatic and alicyclic diol components may be used, or plural kinds of hydroxycarboxylic acids are copolymerized It may be.

  Other polymers having fiber-forming ability of the present invention include polycarbonate polymers formed by transesterification of alcohol and carbonic acid derivatives, polyimide polymers formed by cyclization polycondensation of carboxylic acid anhydrides and diamines, and dicarboxylic acids. Synthesis of polybenzimidazole polymers formed by the reaction of acid esters and diamines, as well as polysulfone polymers, polyether polymers, polyphenylene sulfide polymers, polyether ether ketone polymers, polyether ketone ketone polymers Examples also include polymers derived from natural polymers such as polymers, cellulosic polymers, chitin and chitosan derivatives.

  For these polymers A, as described later, it is preferable that the critical surface tension γcA is large, the tension at the time of stretching is small, and voids are easily developed at the time of stretching. A polyester polymer is more preferable because it can be stretched with a low stretching tension during stretching. Of these polyester polymers, polyester polymers in which the main repeating unit is ethylene terephthalate, propylene terephthalate, butylene terephthalate, or lactic acid are preferred in terms of more versatility and fiber-forming properties, and the main repeating unit is ethylene terephthalate. More preferred are polyester polymers. These polyamide polymers such as nylon 6 or polyester polymers such as polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate both have a critical surface tension γcA of about 43 dyne / cm.

  As the polyester polymer preferable as the polymer A of the present invention, a polyester having an intrinsic viscosity (IV) usually used for a synthetic fiber can be used. Although the lower limit and the upper limit of IV are not particularly limited, for example, when the polymer A and the polymer B are melt-kneaded, a high shear stress is expressed, and as a result, the polymer B is refined in the fiber, and the void forming property is increased. In terms of excellence, for example, polyethylene terephthalate is preferably 0.4 or more, and more preferably 0.5 or more. If it is a polypropylene terephthalate, it is preferable that it is 0.7 or more, and it is more preferable that it is 0.8 or more. If it is polybutylene terephthalate, it is preferably 0.6 or more, more preferably 0.7 or more. Although the upper limit is not particularly limited, it is 1.5 or less for polyethylene terephthalate, for example, in terms of good metering of the gear pump, no unevenness in fineness, and the fiber does not become excessively hard. Is more preferable and 1.3 or less is more preferable. If it is a polypropylene terephthalate, it is preferable that it is 2.0 or less, and it is more preferable that it is 1.8 or less. If it is polybutylene terephthalate, it is preferable that it is 1.5 or less, and it is more preferable that it is 1.4 or less. Polyesters used in the present invention include poly (hydroxycarboxylic acids) represented by polylactic acid that are not evaluated in IV, and these are described in terms of weight average molecular weight (hereinafter sometimes simply referred to as average molecular weight). For example, in the case of polylactic acid, those having an average molecular weight of 50,000 to 500,000 are usually used, preferably 100,000 to 300,000, and an average of 150,000 to 250,000 in view of processability and spinnability Molecular weight polylactic acid is more preferably used.

  The polymer A in the present invention is not particularly limited as long as the content is 50% by weight or more, and any content can be taken. Since the strength of the screen is preferably high, the polymer A content in the fiber is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 85% by weight or more. The upper limit of the content of the polymer A is preferably 99.9% by weight or less, more preferably 99% by weight or more, since the void fiber is composed of at least polymer A and polymer B, and more preferably 98% or more. Even more preferably, it is no more than wt%.

  As the polymer A, one kind of polymers selected from these may be used alone, or a plurality of kinds may be used in combination as long as the gist of the invention is not impaired.

  In the void fiber used in the screen of the present invention, the smaller the average dispersion diameter of the polymer B, which is an island component, is, the higher the void forming property is, and the inclined structure of the void is likely to appear. The average dispersion diameter of the polymer B is preferably 1 μm or less, more preferably 0.8 μm or less, and even more preferably 0.5 μm or less. Moreover, although the lower limit is more preferable, since the polymer A and the polymer B are incompatible with each other, the current limit is 0.01 μm. The average dispersion diameter is the H.D. It is possible to confirm by In addition, when the island component in the fiber is continuous in the fiber axis direction, that is, a core-sheath composite fiber or a sea-island composite fiber, this is not a blend fiber, but a composite interface (interface between the core and the sheath or the interface between the sea and the island) The area of is extremely small compared to the blended fiber, and no voids are formed at all, or even if they are generated, only those different from the void fibers used in the screen of the present invention are obtained.

  The polymer B of the present invention is not particularly limited as long as it is incompatible with the polymer A as described above, and a wide variety of polymers can be used. For example, polyamide polymer, polyolefin polymer, other vinyl polymer, fluorine polymer, silicone polymer, elastomer, polycarbonate polymer, polyimide polymer formed by cyclization polycondensation of carboxylic acid anhydride and diamine, dicarboxylic acid Polybenzimidazole polymers formed by the reaction of esters and diamines, as well as polysulfone polymers, aliphatic polyether polymers, aromatic polyether polymers, polyphenylene sulfide polymers, polyether ether ketone polymers, polymers Examples include synthetic polymers such as ether ketone ketone polymers, cellulose polymers, polymers derived from natural polymers such as chitin and chitosan derivatives, and various other engineering plastics.

  More specifically, for example, polyolefins and other vinyl polymers synthesized by a mechanism in which a monomer having a vinyl group such as radical polymerization, anion polymerization, or cation polymerization is formed by addition polymerization reaction or ring-opening polymerization reaction. In the case of polymers, for example, polyolefins include polyethylene, polypropylene, polybutylene, polymethylpentene homopolymers, copolymers, and derivatives, and other vinyl polymers include polystyrene, polyacrylic acid, polymethacrylic acid. , Polymethyl methacrylate, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene chloride, poly (vinylidene cyanide), and copolymers and derivatives thereof. Among the polymer synthesized by polymerization reaction, the critical surface tension described later, preferable from the viewpoint of density or glass transition temperature Tg,, it can be mentioned first polyolefin polymer.

  Among the preferred polyolefin-based polymers, as a polyolefin whose main repeating structure is an olefin, for example, ethylene, propylene, butene, methylbutene, methylpentene, ethylpentene, hexene, ethylhexene, octene, decene, tetradecene, octadecene are monomers. In addition to the polyolefin used as the polymer, a polyolefin polymer having a cyclic structure represented by the following chemical formula 1, chemical formula 2, or chemical formula 3, for example, synthesized by ring-opening polymerization or addition polymerization of an alicyclic monomer can be given.

  Here, each of the substituents X and Y is a group selected from hydrogen, an alkyl group, an alicyclic group, a cyano group, an alkyl ester group, and an alicyclic ester group.

  Examples of such a structure include “Arton” (registered trademark) manufactured by JSR Corporation, “Zeonor” (registered trademark), “Zeonex” (registered trademark) manufactured by Nippon Zeon Co., Ltd., and the like. The polyolefin having a structure is not particularly limited thereto.

  These polyolefin polymers may be homopolymers using one kind of monomer alone, or may be a copolymer using two or more kinds, and further copolymerize olefins with other vinyl compounds. It may be a copolymer. Specific examples of the copolymer component include vinyl esters of saturated aliphatic carboxylic acids having 2 to 6 carbon atoms, acrylates and methacrylates derived from alcohols having 1 to 20 carbon atoms, Unsaturated carboxylic acids such as fumaric acid, maleic acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, nadic acid or acid halides, amides, imides, acid anhydrides and esters of the unsaturated carboxylic acids, Examples thereof include vinyl compounds such as styrene or styrene derivatives, acrylonitrile or acrylonitrile derivatives, vinyloxyalkyl derivatives (alcohol type or carboxylic acid type), or vinyl compounds having an alicyclic structure. In particular, examples of the polyolefin polymer having the alicyclic structure as a copolymerization component include “Apel” (registered trademark) manufactured by Mitsui Chemicals, Inc. and “Topas” (registered trademark) manufactured by Polyplastics Co., Ltd. However, the copolymerized polyolefin polymer having the alicyclic structure is not limited thereto.

  Among the polyolefin polymers exemplified as preferred among these polymers B, propylene and / or methylpentene are preferred in that the formed fiber has a high void forming property and an inclined structure of voids is easily formed in the fiber cross section. A polyolefin polymer having a main repeating unit, a polyolefin polymer having a cyclic structure, or a copolymerized polyolefin polymer having an alicyclic structure is preferred.

  Further, examples of the polymer B of the present invention include polyether polymers in addition to the polyolefin polymers, and among them, aromatic polyether polymers represented by polyphenylene ether are preferable. The polyphenylene ether may be a homopolymer mainly composed of phenylene oxide, or may be a copolymer obtained by copolymerizing the second component, and may be an additive within a range that does not impair the gist of the invention. It may be a modified polyphenylene ether alloyed with a contained component, that is, a polystyrene polymer, a polyamide polymer, a polyester polymer, a polyolefin polymer, or the like as a second component. Examples of the modified polyphenylene ether include “Yu-Piece” (registered trademark) and “Remalloy” (registered trademark) manufactured by Mitsubishi Engineering Plastics Co., Ltd., and “Noryl” (registered trademark) manufactured by GE Plastics Co., Ltd. Trademark), “Zylon” (registered trademark) manufactured by Asahi Kasei Corporation, “Art Rex” (registered trademark), “Artly” (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., etc. Aromatic polyether-based polymers are exemplified, but not limited thereto.

  Alternatively, the polymer B in the present invention is preferably a polycarbonate polymer. The polycarbonate polymer may be a homopolymer mainly composed of bisphenol A and C═O, or may be a copolymer obtained by copolymerizing the third component, and the gist of the invention is impaired. As long as there are no additives, it may be a modified polycarbonate in which an additive is added, that is, an alloyed polystyrene polymer, polyamide polymer, polyester polymer, polymethacrylate polymer or the like. Examples of the modified polycarbonate include “Iupilon” ((registered trademark) and “Novalex” ((registered trademark)) manufactured by Mitsubishi Engineering Plastics Co., Ltd., and “Lexan” ((registered trademark) manufactured by GE Plastics Co., Ltd.). Trademark), "Caliver" (registered trademark) manufactured by Sumitomo Dow Co., Ltd., "Panlite" (registered trademark) manufactured by Teijin Chemicals Ltd., "Taflon" manufactured by Idemitsu Petrochemical Co., Ltd. (Trademark) and the like, and a preferred polymer B includes, but is not limited to, a polycarbonate-based polymer.

  Further, when a polyester polymer is used as the polymer A, the polymer B preferably has no maleimide structure. In general, the maleimide structure is a structure obtained by reaction of maleic anhydride with ammonia or a primary amine, and there is a structure such as N-alkylmaleimide, N-cycloalkylmaleimide, or N-phenylmaleimide. An N-phenylmaleimide structure is known as an easy-to-treat material. Since the maleimide structure has a particularly high affinity with a polyester-based polymer, the affinity at the interface between the polymer A and the polymer B becomes too high, so that void formation tends to be poor. The reason is not well understood, but in this case, the gap is likely to be generated mainly in the central part of the fiber cross section, and the gap is localized, making it difficult to form an inclined structure. As a result, the light incident on the screen diffuses. Transmission loss is likely to occur. Examples of the polymer that causes the above problem include styrene maleimide polymer (type: MS-NA, etc.) manufactured by Electrochemical Co., Ltd.

  The refractive index nB of the polymer B in the void fiber of the present invention is preferably 1.55 or less. The low refractive index of the polymer B existing inside the fiber gap is preferable because the light incident on the gap is not totally reflected and easily reaches the center of the fiber, and the light incident on the screen is easily diffused. For example, the polyolefin polymer having a cyclic structure, which is preferred as the polymer B in the present invention, is 1.51-1.54, polypropylene is 1.47-1.50, and is polyethylene. 1.51 to 1.54, and 1.463 for polymethylpentene. The refractive index is defined in J.P. It is calculated by the method of

  The refractive index nA-nB of polymer A, which is the difference in refractive index between polymer A and polymer B, is preferably 0.010 or more. When light is incident on the fiber from the surface and total reflection occurs on the surface of the fiber, it is difficult to utilize the light diffusion effect due to the voids inside the fiber, and the screen is likely to be glaring. Decreasing the apparent refractive index of polymer A, which is the main component, makes it easier for incident light to enter the fiber, and the transmitted light is appropriately refracted at the interface between polymer A and polymer B, so that a specific wavelength can be obtained. Since the reflected light is diffused in multiple directions without being intensified, a soft image can be obtained. The refractive index difference is more preferably 0.015 or more, and even more preferably 0.020 or more. The upper limit is not particularly limited, but is preferably about 0.200 or less.

  The average molecular weight of the polymer B of the present invention is not particularly limited, but the number average molecular weight is 2,000 to 2,000 in that the kneadability with the polymer A is excellent and a fine island component is formed in the fiber. It is preferably 10,000,000, more preferably 5,000 to 5,000,000, still more preferably 10,000 to 1,000,000.

  Although the amount of addition of the polymer B of the present invention is not particularly limited, the content is 0 because it becomes more island components and the voids are more easily generated as the area of the interface between the polymer A and the polymer B increases. It is preferably 1% by weight or more, more preferably 1% by weight or more, and even more preferably 2% by weight or more. Further, if the addition amount is too large, the physical properties of the fiber may be lowered and the practical durability of the screen may be lowered. Therefore, it is preferably 30% by weight or less, more preferably 20% by weight or less, Even more preferably, it is no more than wt%.

  As the polymer B in the present invention, one kind of these polymers may be used alone, or a plurality of kinds may be used in combination as long as the gist of the invention is not impaired. Moreover, you may mix | blend polymers other than the polymer A and the polymer B with the unusual cross-section fiber excellent in the lightweight property of this invention in the range which does not inhibit the effect of this invention.

  ΓcA-γcB, which is the difference between the critical surface tension γcA of the polymer A of the present invention and the critical surface tension γcB of the polymer B, represents the affinity at the interface between the polymer A which is the sea component of the fiber and the polymer B which is the island component. The larger γcA-γcB is, the higher the interfacial peelability between polymer A and polymer B is, the better the void formation, and the easier it is to form an inclined structure of voids in the fiber cross section. Although not particularly limited, γcA−γcB ≧ 5 dyne / cm is preferable, and 10 dyne / cm or more is more preferable. However, if the γcA-γcB is too large, the interfacial affinity between the polymer A and the polymer B is low, so that the dispersion form of the polymer B that is an island component in the fiber is easily coarsened, and the number of voids in the fiber is reduced. The area of the interface that diffuses light tends to be small. Therefore, γcA−γcB ≦ 25 dyne / cm is preferable, and γcA−γcB ≦ 20 dyne / cm is more preferable.

  As a combination of polymer A and polymer B satisfying γcA−γcB ≧ 5 dyne / cm, which is preferable in the present invention, for example, polyester including polyethylene terephthalate and polypropylene terephthalate is polymer A, and polyethylene, polypropylene, and polymethyl are used. Examples include a combination of pentene and polyolefin having a cyclic structure such as polyolefin B as a polymer B, or a combination of polyamide 6 such as nylon 6 and nylon 66 as polymer A, and the above polyolefin as polymer B. A combination in which terephthalate or polypropylene terephthalate is polymer A and polymethylpentene or polyolefin having a cyclic structure is polymer B is more preferable.

  In addition, the polymer B of the present invention peels easily at the interface with the polymer A to form voids, and the resulting fiber is more lightweight, so that the critical surface tension γcB of the polymer B is 10 to 10%. It is preferably 35 dyne / cm, more preferably 10 to 33 dyne / cm. As the polymer B satisfying this critical surface tension γcB range, among the polyolefins composed of the above-mentioned olefin monomers or other ethylenically unsaturated compounds, 80 mol of polyolefin having propylene and / or methylpentene and / or a cyclic structure is used. % Homopolymer or copolymer is preferred, methylpentene accounts for 80 mol% or more homopolymer or copolymer is more preferred, and in the combination of polyester as polymer A, the void formation is very excellent, Very preferable. In particular, in the case of a homopolymer or copolymer in which the above-mentioned propylene accounts for 80 mol% or more, 29 to 30 dyne / cm, and in the case of a homopolymer or copolymer in which methylpentene accounts for 80 mol% or more, 24 to 25 dyne / cm. cm, 30 to 32 dyne / cm in the case of a homopolymer or copolymer in which the polyolefin having a cyclic structure occupies 80 mol% or more.

  Moreover, it is preferable that the difference of each glass transition point Tg of the polymer A of this invention and the polymer B is TgB (Tg of polymer B) -TgA (Tg of polymer A)> = 5 degreeC. When the relationship between the glass transition temperatures satisfies TgB-TgA ≧ 5 ° C., the deformation of the polymer B existing in the polymer A is difficult to occur in the drawing process, so that the composite interface between the polymer A and the polymer B is easy to peel off. It is preferable because voids are formed in the layer and the void forming property is high. When TgB-TgA ≧ 5 ° C. is satisfied, the spinning stress applied in the melt spinning process can be mainly borne by the polymer B, and the molecular orientation of the polymer A is restrained, so-called orientation restraining effect is manifested. Magnification can be stretched, the inclined structure of voids can be easily developed, and there are also advantages such as excellent productivity. Further, since the polymer B is elongated and refined in the spinning process, the number of interfaces between the polymer A and the polymer B is increased, and a large number of voids are generated during stretching, which is preferable. For the above reasons, TgB-TgA ≧ 10 ° C. is more preferable, TgB-TgA ≧ 30 ° C. is further preferable, and TgB-TgA ≧ 50 ° C. is particularly preferable. The upper limit of TgB-TgA is 400 ° C. from the viewpoint of melt moldability, preferably TgB-TgA ≦ 300 ° C., and more preferably TgB-TgA ≦ 200 ° C.

  In addition, the weather resistance and heat resistance of the screen are increased, that is, it can be widely used in various climates, so that the polymer A is deformed and the cross-sectional shape of the fiber or the void is deformed to change the reflection characteristics of the screen. It is preferable to avoid such a situation. Therefore, the glass transition point TgA of the polymer A is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 60 ° C. or higher. For the same reason, it is preferable to avoid that the polymer B is deformed and fills the gap even when exposed to a high temperature. For this reason, TgB of the polymer B is preferably 70 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 130 ° C. or higher.

  Examples of combinations of polymer A and polymer B that satisfy TgB-TgA ≧ 5 ° C. preferred in the present invention include, for example, polyesters such as polyethylene terephthalate, polypropylene terephthalate, and polylactic acid, nylon 6, and nylon 66. The polymer A is a polymer A, polystyrene, polymethacryl methacrylate, polycarbonate, a polyolefin having a cyclic structure, a polyphenylene ether polymer B, and the like. The combination of polyethylene terephthalate, nylon 6 and nylon 66 as polymer A, polystyrene, polyolefin having a cyclic structure, and polymer B as polyphenylene ether is more preferable. There. The glass transition temperature of each polymer is defined by C.I. For example, polyethylene terephthalate is about 79 ° C, polypropylene terephthalate is about 47 ° C, polybutylene terephthalate is about 24 ° C, and polylactic acid is about 58 ° C. In the case of nylon 6, it is observed at 71 ° C., respectively.

  In the polymers A and B of the present invention, the relationship between the melting point TmA of the polymer A and the melting point TmB of the polymer B is preferably TmA> TmB. When the relationship of the melting point satisfies TmA> TmB, the polymer B is easy to finely disperse with respect to the polymer A, and the void developability becomes high. Like Tg, it is preferable to avoid that the polymer A is deformed and the cross-sectional shape of the fiber or the void is deformed to change the reflection characteristics of the screen. Therefore, TmA is preferably 160 ° C. or higher. More preferably, the temperature is 210 ° C. or higher, and even more preferably 250 ° C. or higher. It is also preferable to avoid the polymer B existing inside the void from being deformed and filling the void even when exposed to a high temperature. TmB is preferably 150 ° C. or higher, and more preferably 180 ° C. or higher.

The melt viscosity of the polymer B of the present invention is not particularly limited, and a polymer having a shear speed of 10 sec ^{−1 and} a shear viscosity of 500 to 100,000 poise is usually used at the melt spinning temperature of the polymer to be used, preferably 1000 to 50000 poise.

  The void fiber used in the screen of the present invention preferably has a fiber residual elongation of 5% to 50%. Here, the fiber residual elongation is defined by the E.E. defined in the examples described later. It is the value measured by the method. A fiber residual elongation of 5% to 50% is preferable because the shape retention of the screen is high and the film has appropriate stretchability. The fiber residual elongation is more preferably 8% to 40%, and even more preferably 10% to 30%.

  The void fiber used for the screen of the present invention is excellent in lightness. Here, the excellent lightweight property means that the apparent specific gravity of the fiber is preferably 90% or less with respect to the specific gravity of the polymer A. For example, polyethylene terephthalate (PET) is 1.24 or less, and polypropylene terephthalate (PTT). 1.20 or less for polybutylene terephthalate (PBT), 1.13 or less for polylactic acid, 1.02 or less for nylon, 1.0 or less for polypropylene (PP). If it is 81 or less and polyethylene (PE), it indicates 0.85 or less. Void fibers are preferable because they are excellent in light weight and can reduce the screen weight. In view of maintaining higher lightness, the apparent specific gravity of the fiber is preferably 85% or less, more preferably 80% or less, and even more preferably 75% or less with respect to the specific gravity of the polymer A.

  The fiber strength of the void fiber used for the screen of the present invention is preferably 2.5 cN / dtex or more. The fiber strength is more preferably 3.0 cN / dtex or more, still more preferably 3.5 cN / dtex or more, and particularly preferably 4.0 cN / dtex or more.

  As the single fiber fineness of the void fiber used in the screen of the present invention is larger, voids are more likely to be generated, and inclined structures of voids are more likely to be formed. For this reason, the single fiber fineness is preferably 1 dtex or more, more preferably 2 dtex or more, still more preferably 3 dtex or more, and particularly preferably 4 dtex or more. On the other hand, if it is too thick, it is difficult to increase the density of the woven or knitted fabric as a woven or knitted fabric, and light incident on the screen may be transmitted without being diffused by the gap. It is preferably 500 dtex or less, more preferably 300 dtex or less, even more preferably 200 dtex or less, and particularly preferably 100 dtex or less.

  The void fiber used in the screen of the present invention is a matting agent, flame retardant, lubricant, antioxidant, ultraviolet absorber, infrared absorber, crystal nucleating agent, fluorescent whitening agent, terminal group, as long as the gist of the invention is not impaired. A small amount of an additive such as a sealant may be retained.

  Next, the screen manufacturing method of the present invention, in particular, a means for manufacturing void fibers will be described more specifically. In addition, about the structure of the whole screen apparatus and a manufacturing method, since it is not directly related to this invention, since a conventionally well-known method can be utilized, detailed description is abbreviate | omitted.

The void fiber used in the screen of the present invention is preferably manufactured by the melt spinning method because the process is a valve and the productivity is high and the cost is low. The addition method of the polymer B is not particularly limited. , (A) A method in which polymer B is added during spinning of polymer A, and melt kneading is performed under normal pressure or reduced pressure using a kneader such as an extruder or static mixer. (B) Kneading such as extruder or static mixer is performed by adding polymer B to polymer A. After melt-kneading at a high concentration under normal pressure or reduced pressure with a machine, polymer A to which polymer B has not been added is simultaneously added and diluted with a kneader such as an extruder or static mixer during spinning of polymer A, and then normal pressure or reduced pressure. Method of melt-kneading under, (C) Arbitrary before discharge in spinning of polymer A In this stage, the polymer B melt is discharged from a nozzle-like tube, blended by melt shearing in the polymer flow path, and contained in the polymer A, etc., but the polymer B is finely dispersed in the fiber. The method of (A) and (B) is employ | adopted at the point which is easy to do.

  In melt spinning, the spun yarn discharged from the die hole is cooled below the glass transition temperature of the blend composition of the present invention and taken up at a take-up speed of 100 to 10,000 m / min. As the spinning tension is increased and the polymer B is elongated on the spinning line, the polymer B is finely dispersed, and voids are easily generated during stretching. Therefore, it is preferable that the discharged polymer is rapidly cooled. As a means for rapid cooling, an air cooling type or a water cooling type can be adopted.

  For example, when using an air-cooling type cooling means, the yarn is rapidly cooled as the temperature of the cooling air is lower and the distance from the cooling air spray start point to the base is shorter. For this reason, it is preferable that the temperature of cooling air is 30 degrees C or less, It is more preferable that it is 25 degrees C or less, It is still more preferable that it is 20 degrees C or less. The lower limit is not particularly limited. However, if the temperature is too low, a temperature such as 0 ° C. or higher is preferable because the water vapor freezes in the cooling air flow path and causes clogging. Further, as described above, the yarn is rapidly cooled as the distance between the cooling air spray start point and the base is shorter. For this reason, the distance between the cooling air spray start point and the base is preferably 20 cm or less, more preferably 10 cm or less, and even more preferably 5 cm or less. When the cooling air is blown from directly below the base as described above, the base surface may be cooled and the temperature of the base surface may be lowered. If the temperature of the die surface is excessively lowered, unmelted polymer is discharged, and as a result, there is a concern that the fibers become non-uniform. Therefore, it is also preferable to use a heater that locally heats the vicinity of the die.

  For example, when a water-cooled cooling means is used, the discharged polymer is cooled by passing through a water-cooled bath. As the water temperature of the water-cooled bath is lower, the yarn is rapidly cooled as the distance between the point immersed in the water-cooled bath and the base is closer. The cooling water temperature is preferably 70 ° C. or lower, more preferably 50 ° C. or lower, and even more preferably 30 ° C. or lower. Although it does not restrict | limit especially about a minimum, in order to avoid freezing of cooling water, 0 degreeC or more is preferable. The distance between the point where the discharged polymer is immersed in the water-cooled bath and the base is preferably 20 cm or less, more preferably 10 cm or less, and even more preferably 5 cm or less.

  By increasing the draw ratio in the drawing step, voids are densely formed inside the fiber. In order to increase the draw ratio, the take-up speed is preferably low, preferably 4000 m / min or less, more preferably 3000 m / min or less, and still more preferably 2000 m / min or less. On the other hand, as the spinning tension is increased and the polymer B is elongated on the spinning line, the polymer B is finely dispersed and voids are easily generated during stretching. Therefore, the take-up speed is 100 m / min or more, more preferably 1000 m / min or more. It is.

  After being taken up, the film is stretched without being wound up or once taken up. The stretching temperature is preferably a glass transition temperature (TgA) of the polymer A + 100 ° C. or less, more preferably a temperature range of TgA−80 ° C. to TgA + 80 ° C., further preferably a temperature range of TgA−80 ° C. to TgA + 20 ° C. It can be done with.

  The draw ratio has a very strong correlation with the void forming property. The higher the draw ratio, the larger the number of voids, the larger the void diameter, and the void fiber having the void distribution with the larger inclination tendency of the voids. That is, a void fiber having the property of diffusing and not transmitting light can be achieved by high-magnification drawing. The draw ratio may be appropriately changed in order to obtain a desired screen. However, if the draw ratio is too low, no voids are formed. As the film is stretched at a higher magnification, the inclination of the voids increases, and the effect of diffusing light and the effect of not transmitting light are further increased. Furthermore, a skin layer having no voids is simultaneously formed on the fiber surface by stretching, and the skin layer becomes thinner as the stretching ratio is higher. For this reason, it is preferable that the residual elongation after stretching is 5 to 50%, and more preferably 8 to 40%. Most preferably, it is extending | stretching to 10 to 30% of residual elongation.

  The heating method at the time of stretching is not particularly limited if a general-purpose apparatus is used, but external force is applied in a direction other than the fiber stretching direction in that a large number of voids can be formed in the fiber and the formed voids can be hardly crushed. A heating method that does not take place is preferable, and it is preferable to employ a heating method using a heating pin, a heating plate, an apparatus using a heating liquid or a heating gas, or excitation of molecular vibration typified by a carbon dioxide gas laser.

  Moreover, after extending | stretching, the method of heat-processing at the temperature of TgA + 10 degreeC or more is preferable. The space around the voids developed by heat treatment after stretching is heat-set, and a lightweight fiber with excellent heat resistance is obtained. Here, it is important that the heat treatment performed after stretching is performed at a temperature lower than the melting point of the polymer A so that the developed voids are not crushed.

  The heat treatment method after stretching is not particularly limited as long as a general-purpose apparatus is used, but the higher the heating efficiency, the more the fiber structure is fixed without relaxation, and a fiber with high void durability can be obtained. Therefore, it is preferable to employ a heating method using excitation of molecular vibration represented by a heating pin, a heating roller, a heating plate, a device using a heating liquid or a heating gas, a carbon dioxide laser, or the like.

  Further, the above-described spun yarn may be false twisted without being drawn or after being drawn. When the drawn yarn is used in false twisting, it is heated by a contact type or non-contact type method, and false twisted by a disk-like material, a belt-like material, or a pin-like material. When undrawn yarn is used, it is false twisted with a twisted body (disk, pin, belt) after being heated with a contact or non-contact type heater, etc. The Although the false twisted void fiber can be wound as it is, it is preferably wound after being heat set again.

  When the void fiber having an irregular cross section is used in the screen of the present invention, as a method for forming the irregular cross section, for example, the shape of the spinneret hole is a multileaf type such as a three leaf type, a four leaf type, a five leaf type, etc. From the mouthpiece of the present invention, which is a cross-sectional shape capable of forming a deformed cross section such as a polygonal shape such as a triangle, a quadrangle, a pentagon, a gear shape, a C shape, a Y shape, a T shape, a star shape, a flat shape, and an elliptic shape. A method of obtaining a modified cross-section fiber by discharging a blend composition composed of polymer A and polymer B forming a modified cross-section fiber, or a component that can be eluted using a reagent such as an aqueous solution, hot water, or an organic solvent, as a sheath component or As a sea component, a core-sheath composite fiber in which at least a core component or an island component forms a modified cross-section as a core component or an island component is a blend composition composed of polymer A and polymer B forming the modified cross-section fiber of the present invention. Also Ku is after obtaining the sea-island composite fibers, a method can be mentioned to obtain a modified cross-section fibers were eluted sheath component or the sea component. From the viewpoint of simple process and high productivity, a method of discharging from a die hole having a cross-sectional shape capable of forming a deformed cross-section using a blend composition composed of polymer A and polymer B as a single component is preferable.

  In order to obtain a fiber with a high profile in cross section, it is preferable that the polymer is discharged in a form with a high profile. Therefore, the larger the slit length X of the die hole is, the larger the fiber obtained. The deformity of becomes higher. In the case of obtaining a void fiber having a higher degree of irregularity and a high inclination tendency, X / Y, which is the ratio of X and Y, is preferably 2 or more, more preferably 3 or more, and 4 or more Even more preferred. However, if X / Y is too large, the base may become dirty and the pack life may be reduced, leading to a decrease in productivity. Therefore, X / Y is preferably 20 or less, and preferably 15 or less. More preferably, it is even more preferably 10 or less. Further, since the degree of irregularity can be increased as the yarn discharged from the die is rapidly cooled, the shape of the die hole and the cooling condition may be appropriately adjusted in order to form a fiber having a desired degree of irregularity. Of course, when the spun yarn is a multifilament, the shape of the die hole may be the same or different between the single fibers.

  The void fibers used in the screen of the present invention may have poor compatibility because polymer A and polymer B are incompatible. In this case, it is also preferable to add a compatibilizing agent to control the compatibility between the polymer A and the polymer B. The compatibilizing agent in the present invention is a compound that changes the interaction at the interface when blending the polymer B with the polymer A to enhance the compatibility between them and finely disperse the polymer B. As the compatibilizing agent, a wide variety of compounds such as a low molecular compound or a high molecular compound can be employed. For example, as the low molecular compound, sodium dodecylbenzenesulfonate, sodium alkylsulfonate, glycerol monostearate, tetra Anionic or cationic surfactants such as butylphosphonium paraaminobenzenesulfonate and amphoteric surfactants, poly (alkylene oxide) glycols such as polyethylene glycol, methoxypolyethylene glycol, polytetramethylene glycol, and polypropylene glycol, and ethylene oxide / propylene oxide Nonionic surfactants such as copolymers are exemplified.

  Further, as the polymer compound mentioned as the compatibilizer, a polymer compound having high compatibility or affinity for each of the polymer A and the polymer B may be used. For example, a polystyrene polymer or a polyacrylate polymer may be used. , Polymethacrylate polymers, poly (vinyl alcohol-ethylene) copolymers, poly (vinyl alcohol-propylene) copolymers, poly (vinyl alcohol-styrene) copolymers, poly (vinyl acetate-ethylene) copolymers, poly (vinyl acetate-propylene) copolymers , Vinyl-based polymers or copolymers such as poly (vinyl acetate-styrene) copolymers, ionomers, polysaccharides, polyalkylene oxides or poly (alkylenes) that have improved heat resistance and melt plasticity by chemically modifying the side chain moiety. Oxide-ethylene) copolymer, poly (alkylene oxide-propylene) copolymer and other alkylene oxide and vinyl derivatives, or polyalkylene oxide derivatives, alkylene terephthalate and alkylene glycol copolymers, alkylene terephthalate and poly (alkylene oxide) glycol Examples thereof include polymers such as copolymers, copolymers of alkylene terephthalate and polyalkylene diol, and the like. Among them, polystyrene polymer, polyacrylate polymer, polymethacrylate polymer, alkylene terephthalate and alkylene are advantageous in that they have a large effect as a compatibilizing agent and good yarn physical properties when the fiber of the present invention is formed. Preferred are copolymers of glycol, copolymers of alkylene terephthalate and poly (alkylene oxide) glycol, poly (alkylene oxide) glycol, copolymers of alkylene terephthalate and polyalkylene diol, or derivatives of these polymers.

  Specific examples of alkylene terephthalate and polyalkylene diol, a copolymer of alkylene terephthalate and alkylene glycol, a copolymer of alkylene terephthalate and poly (alkylene oxide) glycol, or poly (alkylene oxide) glycol or a derivative thereof, which are considered preferable, are described below. The compatibilizer in the present invention is not limited to these.

  As a copolymer of alkylene terephthalate and polyalkylene diol, an alkylene terephthalate selected from ethylene terephthalate, propylene terephthalate, butylene terephthalate, pentamethylene terephthalate, hexamethylene terephthalate, etc., and polyalkylene diol selected from polyethylene diol, polybutylene diol, etc. One type of each of alkylene terephthalate and alkylene glycol may be used, or a plurality of types may be used. Specific examples include poly (ethylene terephthalate-polyethylene diol) copolymer, poly (propylene terephthalate-polyethylene diol) copolymer, poly (butylene terephthalate-polybutylene diol) copolymer, and the like. .

  As the copolymer of alkylene terephthalate and alkylene glycol, alkylene terephthalate selected from ethylene terephthalate, propylene terephthalate, butylene terephthalate, pentamethylene terephthalate, hexamethylene terephthalate, ethylene glycol, propylene glycol, butylene glycol (or tetramethylene glycol), penta It is a copolymer comprising an alkylene glycol selected from methylene glycol and hexamethylene glycol, and one or more of each of alkylene terephthalate and alkylene glycol may be used. Specific examples include, but are not limited to, polyethylene terephthalate-butylene glycol copolymer, polypropylene terephthalate-ethylene glycol copolymer, polybutylene terephthalate-tetramethylene glycol copolymer, and the like.

  As the copolymer of alkylene terephthalate and poly (alkylene oxide) glycol, alkylene terephthalate selected from ethylene terephthalate, propylene terephthalate, butylene terephthalate, pentamethylene terephthalate, hexamethylene terephthalate, and the like, diethylene glycol, triethylene glycol, poly (ethylene oxide) glycol, A copolymer comprising poly (alkylene oxide) glycol selected from dipropylene glycol, poly (propylene oxide) glycol, poly (ethylene oxide-propylene oxide) glycol composed of a copolymer of ethylene oxide and propylene oxide, and alkylene terephthalate And 1 each of poly (alkylene oxide) glycol It may be used by classes, or may also be used in combination. Although not particularly limited, specifically, polyethylene terephthalate-diethylene glycol copolymer, polyethylene terephthalate-poly (ethylene oxide) glycol copolymer, polybutylene glycol-poly (ethylene oxide) glycol copolymer, polypropylene terephthalate-poly (ethylene oxide) glycol copolymer And so on.

The main chemical structure of poly (alkylene oxide) glycol or its derivative is a group (or group) of aliphatic, aromatic, alicyclic, etc. carbon having a main chain and oxygen atoms bonded alternately. Any poly (alkylene oxide) glycol having a single alkylene oxide as a repeating unit represented by the following general formula (I) can be used.
− [(CH ₂ ) _a —O] _m − (I)
Examples of those satisfying the formula (I) include poly (ethylene oxide) glycol (a = 2), poly (propylene oxide) glycol (a = 3), poly (tetramethylene oxide) glycol (a = 4), and the like. Of poly (alkylene oxide) glycols.

The poly (alkylene oxide) glycol may be an alternating, random, or block copolymer of different alkylene oxides as represented by the following general formula (II), for example.
_{- {[(CH 2) a} -O] m - [(CH 2) b -O] n} x - ··· (II)
As satisfying the formula (II), for example, a poly (oxyethylene-oxypropylene) copolymer (a = 2 or 3, b = 2 or 3, and a and b may be the same or different. ), Poly (oxytetramethylene-oxyethylene-oxypropylene) copolymer (a = 1 or 2 or 3, b = 1 or 2 or 3, and a and b may be the same or different.) For example, copolymers of different alkylene oxides.

  Further, as the poly (alkylene oxide) glycol, the polyalkylene oxide represented by the above general formula (I) or (II) may be used alone or in a range not impairing the gist of the invention. You may use what combined the seed | species or more.

  The content of the compatibilizer in the fiber of the present invention is such that the compatibilization is more effectively expressed, and the fiber properties of the obtained fiber are excellent. The content is preferably 0.1% by weight or more, more preferably 1% by weight or more, based on the weight. Further, when added in a large amount, the interfacial affinity between the polymer A and the polymer B becomes too high, and there is a concern that the void forming property is deteriorated. Therefore, the amount is preferably 50% by weight or less, and more preferably 30% by weight. .

  The method of adding the compatibilizer is not particularly limited as long as it is a method of adding to the blend composition of the polymer A and the polymer B at an arbitrary stage before the completion of melt spinning. For example, (A) In a normal polymerization reaction of polymer A, a method of adding and melting and kneading at an arbitrary stage before the polymerization reaction stops, (B) a compatibilizer in a composition prepared by blending polymer A and polymer B prepared in advance. Add and add a specified amount of compatibilizers, Polymer A and Polymer B to a kneader such as an extruder or static mixer at the same time during melt spinning. And a method of melt-kneading under normal pressure or reduced pressure, etc., and are not particularly limited. Method or (C) is preferably employed.

  EXAMPLES Hereinafter, the present invention will be described specifically and in detail with reference to examples, but the present invention is not limited to the following examples. In addition, the physical-property value in an Example was measured with the following method.

A. Measurement of screen gain and half-value angle A liquid crystal projector is installed on the normal line up to the center of gravity of the screen, and images are projected onto the screen with a constant light output. At this time, the luminance side is scanned left and right and up and down on the projector side (the right side is +, the left side is-, the upper side is +, the lower side is-, both left and right and up and down are scanned from -90 ° to + 90 °), 1 The brightness of the reflected light at each angle was measured in degrees. When the brightness could not be measured in the same direction as the projector (angle 0 °), it was obtained by extrapolating the nearest angle value.

The gain is calculated using the following formulas (2) and (3) from the relationship between the screen brightness (candela / m ² ) and the light output (lumen) of the projector. The larger the gain, the brighter the screen.
Gain = [luminance (candela / m ² ) / illuminance (lux)] × π (2)
Illuminance (lux) = light output (lumen) / projection area (m ² ) (3)
The highest gain was set as the peak gain, and an angle (half-value angle) indicating a half value of the peak gain was measured. Measurements were made in the left-right direction and the up-down direction, and the half-value angle W and half-value angle H were set, respectively.

B. Measurement of Intrinsic Viscosity (IV) A sample was dissolved in an orthochlorophenol solution, a relative viscosity ηr at a plurality of points was determined using an Ostwald viscometer at a temperature of 25 ° C., and extrapolated to an infinite dilution.

C. Measurement of critical surface tension In a film made of polymer A or polymer B having a thickness of 50 μm or more, pure water 72.8 dyne / cm, ethyl alcohol (special grade or higher) 22.3 dyne / cm, dioxane 33.6 dyne / cm, benzene 28.9 dyne 20 ° C., humidity 40-80 using all liquids of organic solvents or aqueous solutions having a surface tension of / cm, hexane 18.4 dyne / cm, 20% aqueous ammonia 59.3 dyne / cm, nitrobenzene 43.4 dyne / cm %, The angle between the solid plane in contact with the droplet and the surface of the droplet in contact with the air layer when the droplet rests on a solid under horizontal standing conditions Was measured as the contact angle θ, and cos θ was plotted against the surface tension of the liquid used (Zisman plot), and completely wetted. That is, the critical surface tension γc was obtained by extrapolating the plotted points of the surface tension when cos θ = 1.

D. Measurement of glass transition temperature (Tg) and melting point (Tm) Using a differential scanning calorimeter (DSC-2) manufactured by PerkinElmer Co., Ltd., it was measured at a heating rate of 16 ° C./min with a sample of 10 mg. Tm and Tg are defined as follows. After observing the endothermic peak temperature (Tm ₁ ) observed once at a rate of temperature increase of 16 ° C./min, hold at the temperature of Tm ₁ + 20 ° C. for 5 minutes and then rapidly cool to room temperature (The quenching time and the room temperature holding time are kept for 5 minutes), and when the measurement is again performed at a temperature rise condition of 16 ° C./min, the endothermic peak temperature observed as a stepwise baseline shift is defined as Tg, The endothermic peak temperature observed as the melting temperature of Tm was defined as Tm.

E. Setting of measurement of fiber strength and residual elongation Using a Tensilon tensile tester (TENSIRON UCT-100) manufactured by Orientec, if it is an undrawn yarn, the initial sample length is 50 mm, the tensile speed is 400 mm / min, and if it is a drawn yarn The fiber strength and the residual elongation were measured at an initial sample length of 200 mm and a tensile speed of 200 mm / min, respectively, and the average values measured five times were used as the measured values.

F. Measurement of Apparent Specific Gravity of Fiber and Polymer and Calculation of Porosity (a) The apparent specific gravity of the fiber is defined in JIS-L-1013: 1999 8.17.1 (published by the Japanese Standards Association, chemical fiber filament yarn test method). Based on the floating and sinking method, a NaBr aqueous solution is used if the apparent specific gravity of the fiber is 1 or more at a temperature of 20 ° C. ± 0.1 ° C., and the heavy liquid is used if the apparent specific gravity of the fiber is between 1 and 0.789. If the apparent specific gravity of the fiber is between 0.789 and 0.659, a mixed liquid using ethyl alcohol as the heavy liquid and n-hexane as the light liquid. Then, after each fiber was allowed to stand for 30 minutes, the equilibrium state of the float and sink was confirmed, and as described in the above section 8.17.1, the specific gravity value of the mixed liquid that did not float or sink was measured, and five fibers were measured. Average ratio of specific gravity values The multiple value (Q) was used.

(B) When the apparent specific gravity of the fiber is less than 0.659 100 g ± 10 g D.D. Weighed in advance using the tubular knitted fabric prepared by the method described in 1. In addition, we fixed the weight of which weight and volume were known in advance to the tubular knitted fabric, and added it to ion-exchanged water prepared at 4 ° C ± 1 ° C. After submerging and defoaming with ultrasonic waves for 5 minutes, the volume of the tubular knitting was measured, and the average value of the specific gravity values of 10 fabrics was defined as the measured specific gravity value (Q).
Moreover, the following formula | equation was used for calculation of the porosity of a fiber.
Porosity (%) = 100 (1-Q / R),
_{R = 100 / [S 1 /} V 1 + S 2 / V 2 + (100-S 1 -S 2) / V p],
However,
S ₁ : addition amount of polymer B (% by weight),
S ₂ : amount of compatibilizer added (% by weight),
V ₁ : density of polymer B (g / cm ³ ),
V ₂ : density of compatibilizer (g / cm ³ ),
V _p : density of polymer A (g / cm ³ )
R: Apparent specific gravity of fiber in the absence of voids For the density, the value measured based on the density gradient tube method defined in JIS-L-1013 is used. For example, when polymer A is polyethylene terephthalate, unstretched For example, 1.34 is used for the yarn, and 1.38 is used for the drawn yarn. For example, when the polymer A is nylon 6, 1.130 is used for the undrawn yarn, and 1.30 is used for the drawn yarn. 138 was used.

G. Calculation of irregularity Blocks with embedded fibers in epoxy resin are subjected to metal dyeing as needed, and an embedded block is produced in which a cross section of single fiber is obtained by cutting in a direction perpendicular to the fiber axis with an ultramicrotome. The cross-sectional observation is performed by scanning electron microscope (SEM) and observation device (FE-SEM S-800 type manufactured by Hitachi, Ltd.) at an acceleration voltage of 6 kV and an arbitrary magnification of 1000 to 20000 times. Digitized photos. In the cross-sectional photograph, the ratio (D1 / D2) of the circumscribed circle diameter D1 and the inscribed circle diameter D2 in the cross section of the single fiber was calculated under the above-mentioned conditions, and was defined as the degree of irregularity.

H. Confirm the incompatibility, average diameter, and discontinuity of polymer B. Metal dyeing is applied to the block in which the fiber is embedded in an epoxy resin, and it is cut in a direction perpendicular to the fiber axis with an ultramicrotome. An ultrathin section having a single fiber cross section is prepared, and traversed at an arbitrary magnification of 5000 to 1000000 times at an acceleration voltage of 75 kV using a transmission electron microscope (TEM) and an observation device (H-7100FA type manufactured by Hitachi, Ltd.). Surface observation was performed and the resulting photographs were digitized. The cross-sectional photograph was image analyzed with WinROOF (version 2.3) manufactured by Mitani Corporation, a computer software, to confirm the incompatibility and discontinuity of polymer B. About incompatibility, the area of all the polymer B which exists on a cross-sectional photograph was calculated, respectively, and it evaluated by the average value of the diameter of the polymer B calculated judging that it was substantially circular from this area value. Furthermore, the discontinuity of polymer B is not necessary when 10 cross-sectional photographs are taken at an arbitrary interval of at least 10,000 times the single fiber diameter, and the average value and distribution of the diameter of polymer B differ depending on the cut surface location. Determined to be continuous. The case of being discontinuous was evaluated as ◯, and the case of being continuous or without polymer B was evaluated as ×.

  I. Confirmation of the number of voids, diameter, discontinuity, and inclination tendency.

A single fiber is placed on the carbon tape affixed to the sample stage, and after platinum deposition (deposition film pressure: 25 to 50 Å, treatment time: about 120 seconds), focused ion beam (FIB) cutting-scanning With a scanning electron microscope (SEM) observation device (STRAIDB235 manufactured by FEI), rough cutting (current: about 7000 pA, processing time: about 20 minutes) and precision cutting (with a Ga focused ion beam accelerated at an acceleration voltage of 30 kV) (Current: about 3000 pA, treatment time: about 4 minutes), and when observing a single fiber cross section in an atmosphere with a degree of vacuum of 1.4 × 10 ⁻¹³ Pa, the sample should be perpendicular to the fiber axis direction. In the case of cutting and observing the single fiber longitudinal section, the sample was cut in parallel to the fiber axis direction with a length of 5 times or more the single fiber diameter. After cutting, using a scanning electron microscope possessed by the apparatus, in an atmosphere with a degree of vacuum of 1.4 × 10 ⁻¹⁹ Pa, with a sample inclination of 52 degrees and an acceleration voltage of 5 kV, the magnification is 80000 times. The single fiber transverse section and the single fiber longitudinal section were observed. At this time, when the whole image of the fiber cross section and the vertical cross section could not be taken at the magnification, partial pictures were taken at the respective positions and pasted using image software to obtain the whole image. First, for the single fiber cross-sectional photograph, computer software WinROOF (version 2.3) manufactured by Mitani Shoji Co., Ltd. was used to calculate the number of voids present in the entire fiber cross-section and the average value of the void diameter by image analysis. . The average value of the diameter of the voids is calculated by calculating the equivalent circle diameter from the area of all the voids existing on each cross-sectional photograph, calculating the equivalent circle diameter, and dividing the sum of the equivalent circle diameters by the total number of voids. By returning, the average value of the diameters was obtained.

  Furthermore, when the fiber cross-sectional shape is similar to the fiber cross-sectional shape sharing the center of the fiber cross-section and is divided into the outer layer portion and the inner layer portion of the fiber by the cross-sectional shape having a diameter of ½, the average diameter d1 of the voids existing in the outer layer portion and the inner layer portion The average diameter d2 of the existing voids was calculated by the above-described image analysis method, and the value of d2 / d1 was obtained. Moreover, when there was no space | gap in an outer layer part, it judged that it did not have an inclination structure and described x.

  Furthermore, regarding the discontinuity of the voids, the above cross-sectional observation is performed 10 times at an arbitrary interval of 1000 times the diameter or more, the number of voids in each cross-section does not match, and further, the longitudinal cross-sectional observation is discontinuous in the fiber axis direction. When it was confirmed that at least one void was present, it was determined that the void was discontinuous. Evaluation was made as ○ when the gap was discontinuous in the fiber axis direction, and x when the gap was continuous or not.

J. et al. Measurement of Refractive Index Using a chip-like polymer, compression hot press molding was performed at a temperature of melting point + 30 ° C., and immediately water-cooled to obtain an unoriented amorphous film. The refractive index of the film at D line (587.6 nm) at 25 ° C. was measured with an Abbe refractometer.

Example 1
To a low polymer obtained by ordinary esterification reaction from 166 parts by weight of terephthalic acid and 75 parts by weight of ethylene glycol, 0.03 part by weight of 85% phosphoric acid aqueous solution as a coloring inhibitor and antimony trioxide as a polycondensation catalyst The polycondensation reaction was performed by adding 0.06 parts by weight of cobalt acetate tetrahydrate as a toning agent to obtain a poly (ethylene terephthalate) having a commonly used IV 0.65. This polyester is used as polymer A, and polymer B as norbornene resin arton (grade F5023 specific gravity 1.08 g / cc, critical surface tension about 31 dyne / cm, Tg 166 ° C., hereinafter abbreviated as arton) can be obtained. The hopper is filled with a dry blend that is in a chip state so as to be 8% by weight with respect to the total weight of the irregularly shaped blend fiber, and melt spinning is performed at a spinning temperature of 290 ° C. using a twin screw extruder. At that time, after the polymer discharged from the die was cooled with cooling air, the polymer was taken out at a take-up speed of 1200 m / min to obtain a blend fiber having a round cross-sectional shape.

When the obtained blended fiber is stretched, the yarn feeding speed of the yarn feeding roller is 10 m / min, and a stretching ratio is set using a hot water bath at 80 ° C. as a heat source for stretching between the first roller and the second roller. After drawing at 5.0 times and heat-treating the second roller at 150 ° C., the yarn was cooled to Tg of polyester or lower with a cold roller and wound up to obtain a void fiber of 150 dtex-36 filament. A plain fabric having a warp of 175 yarns / inch (25.4 mm), a weft yarn of 85 yarns / inch, and a basis weight of 160 g / m ² is produced using the void fiber, and the reflective surface is 1626 mm wide by using the fabric as a reflective surface of the screen. A screen having a length of 1219 mm was produced.

  The obtained screen was a screen in which the brightness of the projected image hardly changed when viewed from any direction, and had no image obstruction such as a hot spot. Further, the screen gain was 0.9, there was no half-value angle in both the width direction and the height direction, and the screen was a diffusion type screen in which the gain hardly changed depending on the viewing angle. Moreover, it was a screen in which the reflection characteristics did not change due to abrasion or bending caused by cleaning of the reflecting surface. The results of Example 1 are shown in Table 1.

Examples 2-4, Comparative Example 1
In Example 1, the discharge amount was changed during melt spinning, and a 150 dtex-36 filament void fiber produced by changing the draw ratio was used in the same manner as in Example 1, Examples 2 to 4, Comparative Example 1 screen was produced. Further, a screen of Comparative Example 2 was produced in the same manner as Example 1 except that polymer B was not added. The results of Examples 2 to 4 and Comparative Example 1 are shown in Table 1.

  As can be seen from Table 1, it can be seen that the more the fibers produced at a higher draw ratio are used, the larger the number of voids present in the void fibers and the inclination tendency of the voids, and the higher the peak gain of the screen. Further, the obtained screen had no half-value angle even when having a high peak gain, and the projected image had a light diffusibility in which the brightness hardly changed when viewed from any direction. The screen using the normal polyester fiber shown in Comparative Example 1 has no voids inside the fiber, has no light diffusibility, and has a large transmission loss of incident light. Therefore, the peak gain is low, The half-value angle is small. As a result, the image was dark and the screen brightness varied depending on the viewing angle.

Comparative Example 2
In Example 1, a 150 dtex-36 filament hollow fiber was prepared in the same manner as in Example 1 except that the polymer B was not added and a spinneret forming a hollow fiber was used as the spinneret. A screen was produced in the same manner as in Example 1 using this hollow fiber. The results of Comparative Example 2 are shown in Table 1.

  The screen of Comparative Example 2 does not have the polymer B and has only a hollow portion with one hole. For this reason, since the diffusibility of incident light is low and the transmission loss is also large, the peak gain is low and the half-value angle is small. As a result, the image was dark and the screen brightness varied depending on the viewing angle. In addition, since the hollow portion is continuously present in the fiber axis direction, the screen is easily crushed by bending or wear such as cleaning, and has a poor durability.

Examples 5-8
In Example 1, the screens of Examples 5 to 8 were produced in the same manner as Example 1 except that the amount of polymer B added was changed. In Example 8, since yarn breakage occurred frequently at the time of drawability, a screen was prepared using void fibers obtained by adjusting the draw ratio and the discharge amount again. The results of Examples 5-8 are shown in Table 2.

  As is clear from Tables 1 and 2, Examples 1, 6 and 7 were excellent screens with high screen gain and large half-value angle compared to Examples 5 and 8. That is, in the present invention, the polymer B has an appropriate amount of content, the number of voids is large, the void diameter is large, and void fibers having a large inclination tendency of the voids are used to produce a screen. It became a thing.

Examples 9, 10
In Example 1, in Example 9, polymethylpentene (TPX, type RT18, hereinafter the same product was used as polymer B) as polymer B was used, and in Example 10, electrochemical industry was used. Similar to Example 1 except that styrene maleimide copolymer (MSN, average molecular weight of about 110,000, specific gravity of 1.18 g / cc, critical surface tension of about 39 dyne / cm, hereinafter abbreviated as MSN) was used. Thus, a screen was produced. The results of Examples 9 and 10 are shown in Table 3.

  As is clear from Tables 1 and 3, the screens of Examples 9 and 10 showed high reflection characteristics with a high peak gain and no half-value angle. However, compared with Example 1, it was one step away. In Example 9, a void fiber having a smaller number of voids than that in Example 1 is adopted, and in Example 10, a void inclination tendency is small and a refractive index of polymer B is larger than that of polymer A. The fiber was adopted. That is, by using the void fiber obtained by selecting the polymer B which is preferable in the present invention, the light diffusion effect due to the voids inside the fiber can be easily utilized, and the reflection characteristics of the screen are further improved.

Examples 11-14
In Example 1, Example 11 uses PMP as polymer A, Example 12 uses Toray's nylon 6 amylan (type CM1017, hereinafter abbreviated as nylon 6), and Example 13 uses the following (i) method. Polymerized polytrimethylene terephthalate (hereinafter abbreviated as PTT) was used, and in Example 14, polylactic acid (hereinafter abbreviated as PLA) synthesized by the method (ii) below was used. Co., Ltd. transparency resin (TOPAS grade 6017 specific gravity 1.02 g / cc, critical surface tension about 32 dyne / cm, Tg 170 ° C., hereinafter abbreviated as “topas”), spinning temperature was 270 ° C. A screen was prepared in the same manner as in Example 1 except that cold drawing was performed without using a hot water bath. The screens of Examples 11, 13, and 14 were screens having excellent reflection characteristics at the same level as in Example 1. However, since the refractive index difference between Polymer A and Polymer B was too small, Example 1 and Compared to one step. Table 3 shows the results of Examples 11-14.
(i) Polymerization of PTT 130 parts (6.7 mol parts) of dimethyl terephthalate, 114 parts (15 mol parts) of 1,3-propanediol, 0.24 parts (0.014 mol parts) of calcium acetate monohydrate Then, 0.165 parts (0.01 mole part) of lithium acetate dihydrate was charged, and a low polymer obtained by conducting the transesterification reaction while distilling off methanol was added to 0.065 part of trimethyl phosphate and titanium tetra While adding 0.134 parts of butoxide and distilling off 1,3-propanediol, a polycondensation reaction was performed to obtain a chip-like prepolymer. The obtained prepolymer was further subjected to solid phase polymerization at 220 ° C. under a nitrogen stream to obtain PTT of IV1.12.
(ii) Polymerization of PLA 0.005 part by weight of tin octylate as a catalyst was added to 300 parts by weight of L-lactide, and after nitrogen substitution, the reaction was carried out at 170 ° C. to obtain PLA having a weight average molecular weight of 153,000. Got.

Example 15, Comparative Example 3
In Example 1, a screen of Example 15 was produced in the same manner as Example 1 except that a spinneret capable of forming a flat cross section was used.

  Further, a screen of Comparative Example 3 was produced in the same manner as in Example 15 except that Polymer B was not added. The results of Example 15 and Comparative Example 3 are shown in Table 4.

  As can be seen from Table 4, in the present invention, by adopting a flat deformed cross-section fiber to produce a screen, incident light was appropriately recurred, resulting in a screen with a high gain in a specific region. Furthermore, since the cross-sectional shape is an irregular cross-section, the inclination tendency of the voids existing in the void fiber is large, and the half-value angle is large while having a high peak gain. For this reason, the projected image obtained a sharp image with high contrast even in a bright room.

  The screen using the normal polyester fiber shown in Comparative Example 3 has no voids inside the fiber, and thus has no light diffusibility. The peak gain showed a good value, but the half-value angle was The screen was extremely small and could not withstand practical use.

Examples 16-19
In Example 1, a spinneret capable of forming a three-leaf type cross section was used, and the nozzle hole specifications were changed so that fibers having different degrees of deformation were obtained. A screen was made. The results of Examples 16-19 are shown in Table 4.
As can be seen from Table 4, it can be seen that the recursiveness of the incident light can be controlled and the gain in a specific region can be increased by changing the degree of deformation of the modified cross-section fiber employed in the present invention. Furthermore, the higher the profile, the greater the inclination tendency of the voids present in the void fibers, and the half-value angle can be kept large while having a high peak gain. For this reason, the projected image has become a screen on which a sharp image with high contrast can be obtained even in a bright room.

  The screen of the present invention has a characteristic that the gain is high over a wide viewing angle, and the change in gain due to the viewing angle is small. The above characteristics can be controlled by the number of gaps, size, inclination tendency, difference in refractive index between polymer A and polymer B, and by adopting a modified cross section, the gain in a specific viewing angle region is high and the gain depending on the viewing angle. The change is also a small screen. For this reason, it has excellent reflection characteristics without a complex multilayer structure, and the specific gravity of the void fiber used is smaller than the specific gravity of the solid fiber, so it can be reduced in weight as a large screen, and installation and transportation work can be simplified and manufactured. Simplification of the process and downsizing of incidental equipment such as a hoisting motor are possible, so that the manufacturing cost can be greatly reduced. And since many voids exist discontinuously in the longitudinal direction of the fiber, deformation of the voids can be suppressed even if bending or wear occurs, and the void structure does not change due to screen cleaning, folding or winding, etc. It is excellent.

  From the above, it can be used suitably in various types such as fixed type, roll-up type, folding type, etc., and it can be used for theatrical screening, home theater, presentation, gaming, amusement park, etc. It can also be suitably used for mobile use.

It is explanatory drawing which shows the method of calculating the irregularity degree in this invention.

Explanation of symbols

1: circumscribed circle 2: inscribed circle D1: diameter of circumscribed circle D2: diameter of inscribed circle

Claims (4)

  It is a fiber in which two components that are incompatible with each other of polymer A and polymer B are blended, and there are voids inside the fiber, and there are 300 or more voids in the fiber cross section perpendicular to the fiber axis direction. A screen characterized by using void fibers.   2. The screen according to claim 1, wherein void fibers having an average diameter of voids existing in a fiber cross section of 0.01 μm or more and 1 μm or less are used. Within the fiber cross section, the average diameter of the voids existing in the outer layer part when the fiber is divided into an outer layer part and an inner layer part by a cross-sectional shape similar to the fiber cross-sectional shape sharing the center of the fiber cross section and having a diameter of ½. 3. The screen according to claim 1, wherein void fibers having an inclined structure of voids satisfying the following expression (1) are used: a ratio between d1 and an average diameter d2 of voids existing in the inner layer portion.
d2 / d1 ≧ 1.3 (1)   The screen according to any one of claims 1 to 3, wherein a void fiber having a cross-sectional shape of an irregular cross-section is used.

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