JPH09258373A - Support for photographic sensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a syndiotactic polystyrene type support for the photographic sensitive material keeping its intrinsic superior property and transparent and superior in surface flatness and small in curling tendency by controlling the difference of refractive indices in the thickness direction between the surface and the reverse surface of the support. SOLUTION: The nonstretched amorphous support comprising the syndiotactic polystyrene is biannually stretched and oriented and set by heating and the difference of refractive indices in the thickness direction between the surface and reverse surface is controlled to <=4×10<-3> , preferably, <=2×10<-3> , and especially, infinitesimally nearer to zero, and if its difference is over 4×10<-3> , the support curls with the side higher in the refractive index inside, and a flat support cannot be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a syndiotactic polystyrene support, and more specifically, a syndiotactic polystyrene support having no difference between front and back, transparent, flat surface and curl-free. It is about.

As a field requiring this technique, a support is
Successful coating in the field of subsequent processing into products, for example, photographic film, roentgen film, magnetic tape, magneto-optical disk, drawing processes (coating layer coating, emulsion layer coating, magnetic layer coating, etc.) It can be applied to things that cannot be done, slits, dimensional accuracy is changed in the punching process, and flatness deterioration due to curling is disliked.

[0003]

2. Description of the Related Art A syndiotactic polystyrene (hereinafter abbreviated as SPS) support is an excellent thermal, mechanical, physical, chemical and optical material which a polyethylene terephthalate (hereinafter abbreviated as PET) support has. In addition, it has excellent optical properties (light transmittance, haze, etc.) and dimensional stability. Therefore, the SPS-based support is
Photographic material use (color, X-ray, printing material, etc.),
Magnetic recording applications (audio, video, floppy, etc.),
Suitable for electrical applications (capacitors, electrical insulating materials, etc.), vapor deposition applications, packaging applications, etc.

However, the SPS polymer is a crystalline polymer, and its crystallization speed is higher than that of a general-purpose polyester polymer (PET, polyethylene-2,6-naphthalate, etc.) which belongs to an amorphous polymer. Is extremely fast, and it is not possible to produce the required substantially amorphous unstretched raw material in the process of forming the SPS-based support film, various types of SPS-based biaxially oriented heat-fixed supports are obtained. Have an adverse effect. For example, when a molten and extruded SPS polymer is cooled and solidified by a cooling drum to produce an amorphous unstretched raw material, the surface in contact with the cooling drum surface is rapidly cooled and solidified to be transparent in an amorphous state. However, the opposite surface that is not in contact with the cooling drum surface is air-cooled and SP
Even if it is cooled by the cooling drum through the S-based polymer,
Insufficient cooling will result in slow cooling,
It will crystallize and become cloudy. A general-purpose polyester polymer, which is an amorphous polymer, has a slow crystallization speed, so this phenomenon is unlikely to occur, but when the unstretched raw fabric thickness is as thick as several mm, the surface not in contact with the cooling drum rarely crystallizes. The phenomenon that it becomes cloudy occurs. When such a crystallization phenomenon occurs, when a biaxially oriented heat-fixed support is used, the haze becomes large and haze becomes large. The surface side that is not in contact with the cooling drum is crystallized, and the surface flatness is impaired. A density gradient occurs in the support, which causes a difference in the crystallinity of the front and back of the support, resulting in an orientation of the front and back of the support, in other words, a difference in the refractive index in the thickness direction and curling, which causes various phenomena. Various measures have been taken to prevent the occurrence of these phenomena. That is, when manufacturing an unstretched raw fabric, a)
Cooling air is blown from the non-contact side of the cooling drum of the unstretched raw fabric to cool, solidify, and suppress crystallization. B) The cooling drum is immersed in half the cooling bath to cool the unstretched raw fabric in the cooling bath. In order to prevent crystallization from cooling and solidifying from both sides, c) an unstretched raw fabric is sandwiched between two cooling drums to cool and solidify from both sides and suppress crystallization. ing.

Since the SPS polymer has a high crystallization speed, it is not possible to sufficiently suppress the crystallization even with the above-mentioned measures, and the SPS polymer is halogenated with alkylstyrene such as methylstyrene, chloromethylstyrene, chlorostyrene or the like. (Alkyl) styrene, alkoxystyrene,
Copolymerize copolymer components such as vinyl benzoate,
Although it suppresses crystallization, it has the drawback that the properties inherent to the SPS polymer (for example, mechanical properties) are impaired as the amount of copolymerization components increases.

In any case, it is necessary to maintain the various properties originally possessed by the SPS polymer and prevent the above-mentioned phenomenon from occurring.

Further, the support is generally used by winding it around a core in a process such as production, transportation and storage. In this case, even if a flat support is manufactured, if it is rolled and stored, curling curls will occur and various troubles will occur during processing or when it is used as a product, so pull out the support from the core. When
It is required to be flat without curling.

Japanese Patent Application No. 7-2 describes a method for eliminating curling curl that occurs when storing in such a roll.
21999, i.e., a syndiotactic polystyrene-based support wound in a roll form at a temperature of 40 ° C or higher and a glass transition temperature (Tg ° C) or lower of 0.1 to 1500.
The heat treatment for a long time can eliminate the curling curl that has occurred. Therefore, the flatness of the support at the time of production becomes an important factor when using it as a single sheet. The inventors arrived at the present invention by finding that the flatness of the support during production is governed by the structural factors of the support and cannot be eliminated by the heat treatment described above.

[0009]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide the SPS-based support with excellent inherent properties (thermal,
It is intended to provide a support for SPS-based photographic light-sensitive material, which retains mechanical properties, physical properties, chemical properties, dimensional stability and the like), is transparent, has excellent surface flatness, and has little curl.

[0010]

[Means for Solving the Problems] A support obtained by orienting (stretching) an unstretched amorphous support made of an SPS-based polymer in both longitudinal and transverse directions and thermally fixing the support in the thickness direction of the front and back of the support. The object of the present invention is achieved by the support for SPS-based photographic light-sensitive material having a difference in refractive index of not more than a specific value.

That is, an unstretched amorphous support made of an SPS polymer is oriented (stretched) in both longitudinal and transverse directions and heat-fixed, and the difference in refractive index between the front and back of the support in the thickness direction. The object of the present invention is achieved by the support for SPS-based photographic light-sensitive material having an A of 4 × 10 ⁻³ or less.

The present invention will be described in more detail below. First, the syndiotactic polystyrene of the present invention will be described.

In the present invention, syndiotactic polystyrene means syndiotactic polystyrene (SP
S) as a main component, and the stereoregular structure (tacticity) is mainly a syndiotactic structure, that is, a phenyl group or a substituted phenyl which is a side chain with respect to the main chain formed from carbon-carbon bonds. A group has a steric structure in which the groups are alternately located in opposite directions, and the main chain of the main chain is a styrene-based polymer which is a racemo chain, or a composition containing the same, which is a styrene homopolymer. If
It is possible to polymerize by the method described in JP-A No. 62-117708, and other polymers can be polymerized by the method described in JP-A Nos. 1-46912 and 1-178505. Obtainable.

The tacticity is quantified by a nuclear magnetic resonance method ( ¹³ C-NMR method) using isotope carbon. ^The tacticity measured by the ¹³ C-NMR method can be indicated by the abundance ratio of a plurality of continuous constitutional units, for example, diad in the case of 2 units, triad in the case of 3 units, and pentad in the case of 5 units. However, the styrene-based polymer mainly having a syndiotactic structure referred to in the present invention is usually a racemic diad of 75% or more,
Preferably 85% or more, or racemic triad 60
% Or more, preferably 75% or more, or racemic pentad 30% or more, preferably 50% or more.

Specific monomers of the polymer constituting the syndiotactic polystyrene-based composition include styrene, alkylstyrene such as methylstyrene, halogenated (alkyl) styrene such as chloromethylstyrene and chlorostyrene, alkoxystyrene, A single or a mixture containing vinyl benzoate as a main component.

The polystyrene-based resin having a syndiotactic structure of the present invention uses the above-mentioned raw material monomers as a catalyst for polymerization and is disclosed in JP-A-5-320448, p.
(A) Transition metal compound and (b) described on page 10
Those containing aluminoxane as a main component, or (b) (a)
It can be produced by polymerization using a compound containing, as a main component, a transition metal compound and a compound capable of reacting with the transition metal compound (c) to form an ionic complex.

To produce the styrenic polymer used for the support of the present invention, first the styrenic monomer is thoroughly purified and then polymerized in the presence of any of the above catalysts. At this time, the polymerization method, polymerization conditions (polymerization temperature, polymerization time), solvent, etc. may be appropriately selected. Usually from -50
At a temperature of 200 ° C, preferably 30-100 ° C,
Polymerization is carried out for 1 second to 10 hours, preferably 1 minute to 6 hours. As the polymerization method, any of a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method and the like can be used, and either continuous polymerization or discontinuous polymerization may be used. Here, in solution polymerization, as a solvent, for example, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, and aliphatic hydrocarbons such as cyclopentane, hexane, heptane, and octane may be used alone or in combination. It can be used in combination. In this case, the monomer / solvent (volume ratio) can be arbitrarily selected. The molecular weight and composition of the polymer may be controlled by a commonly used method. The molecular weight can be controlled by, for example, hydrogen, temperature, monomer concentration and the like.

In the purification of the styrene-based monomer, the catalyst, the solvent, etc. used, the washing of the polymerization kettle, etc., it is necessary to pay close attention not to mix foreign matters.

Polymerization catalyst (a) (a) transition metal compound and (b) aluminoxane as a main component, or (b) ionic by reacting with (a) transition metal compound and (c) transition metal compound A compound containing a compound capable of forming a complex as a main component is used, and each of the above (a) and (b) contains Ti, Zr, Cr, V, Nb, Ta and Al metal. The amount of the catalyst is very small, and most of it is dissolved and does not precipitate as a metal, but rarely in the polymer, or in the film forming process, together with the metal of the polymer extrusion filter material, such as bronze. May be deposited as foreign matter.

When the polymer is polymerized in a batch system, the molten polymer is extruded and cut into pellets, foreign matter (for example, dust) must be thoroughly excluded from the outside. In addition, foreign substances that cannot be avoided during polymer polymerization were removed by a process of cutting into pellets, using a mesh or a metal powder sintering type filter having a coarser mesh than a film forming filter. Better. It is considered that the polymer is removed by a filter during the film forming process, but it may not be completely removed. Therefore, it is preferable to remove it as much as possible in the process before the film forming. The same applies to continuous polymerization.

The molecular weight of the SPS film of the present invention is not limited as long as it is formed, but the weight average molecular weight is preferably 10,000 to 3,000,000, and particularly 30,000. It is preferably from about 1,500,000. The molecular weight distribution (weight average molecular weight / number average molecular weight) at this time is preferably 1.5 to 8. This molecular weight distribution can be adjusted by mixing different molecular weights. In addition, other monomers copolymerizable with these may be copolymerized to the extent that the effects of the present invention are not impaired.

The SPS-based support of the present invention is preferably SPS alone prepared from styrene, but as a support further containing SPS, SPS has an isotactic structure whose main chain is a meso-chain. By mixing the styrene polymer (IPS), the crystallization rate can be controlled, and a stronger support can be obtained. When mixing SPS and IPS, the ratio depends on the stereoregularity of each other, but is 30:70.
˜99: 1, preferably 50:50 to 98: 2.

The support may contain inorganic fine particles, an antioxidant, a UV absorber, an antistatic agent, a dye, a pigment, a dye, etc., in order to impart functionality, within a range not impeding the object of the present invention. Is also good.

The polymer used for forming the SPS polymer film preferably has a weight average molecular weight of 10,000 or more, more preferably 30,000 or more. When the weight average molecular weight is less than 10,000, it is impossible to obtain a support having excellent strength characteristics and heat resistance. The upper limit of the weight average molecular weight is not particularly limited, but 1,5
When it is more than 100,000, it is not preferable because breakage occurs due to an increase in stretching tension.

In the present invention, the support is oriented and heat-fixed in both longitudinal and transverse directions, and the difference in refractive index between the front and back of the support in the thickness direction must be 4 × 10 ^-3 or less, More preferably, it is 2 × 10 ⁻³ or less. It is preferable that the lower limit of the difference in the refractive index between the front and the back of the support in the thickness direction is as close to 0 as possible.

If the difference in the refractive index in the thickness direction between the front and back of the support is larger than this, curling is performed with the side with the larger refractive index in the thickness direction being the inside, and a flat support cannot be obtained.

The method for producing the SPS-based support of the present invention is not particularly limited as long as the difference in the refractive index between the front and back of the support in the thickness direction is 4 × 10 ⁻³ or less.

That is, in the well-known method for producing an SPS-based support, the cooling rate is not applied to the front and back of the support in any of the steps of extrusion, casting, longitudinal stretching, transverse stretching and heat setting. It is preferable not to make a difference in the refractive index in the thickness direction of the front and back of the support by not making a difference.

For example, when an SPS polymer is extruded and solidified by cooling to prepare an unstretched support, a substantially non-oriented crystalline SPS polymer raw material is pelletized.
It is dried at 120 to 180 ° C. for 1 to 24 hours under vacuum or normal pressure under an atmosphere of inert gas such as air or nitrogen. The target moisture content is not particularly limited, but is 0.0 from the viewpoint of preventing reduction in mechanical strength and the like due to hydrolysis.
5% or less, preferably 0.01% or less, more preferably 0.005% or less, and melt and extrude at 280 to 350 ° C. When a biaxially oriented support is used, in order to make no difference in the refractive index in the thickness direction of the front and back of the support, one side is cooled and solidified on a casting drum of 10 to 40 ° C, and the other side of the casting drum is also the same. An SPS-based polymer unstretched original fabric is produced by forced air cooling so as not to cause a difference in crystallinity between the front and back of the unstretched support, in other words, a density.

The standard of the cooling rate is preferably 12 ° C./sec or more, but it is not particularly limited as long as the difference in refractive index between the front and back of the support in the thickness direction satisfies the range of the present invention.
Here, the cooling rate is the difference between the temperature of the polymer immediately before contacting the drum and the temperature of the support at the time of leaving the drum when the molten polymer is cooled and solidified on the casting drum, and the support contacts the drum surface. Expressed as divided by time.

Next, the unstretched SPS polymer support is biaxially stretched and biaxially oriented. As a method for stretching the SPS-based unstretched support, a sequential biaxial stretching method in which longitudinal stretching and transverse stretching are sequentially performed is preferable. First, 105 to 150 ° C. in the longitudinal direction.
110 to 160 ° C in the transverse direction after stretching 2.0 to 5.0 times at {(Tg + 10) ° C to (Tg + 50) ° C}
It is obtained by stretching 2.0 to 5.0 times at {(Tg + 15) ° C. to (Tg + 60) ° C.}, and then heat setting at 170 to 270 ° C. for 3 seconds to 100 seconds. In addition, here Tg
Represents the glass transition temperature (° C.) of the SPS-based support, which is approximately 95 to 100 ° C.

At this time, since the SPS-based support is oriented, the refractive index in the longitudinal and lateral directions is small, and the refractive index in the thickness direction is large, so that the mechanical strength is ensured. Therefore, the refractive index in the vertical and horizontal directions is both 1.585 or less, preferably 1.580 or less. The lower limit of the refractive index is not particularly limited, but is 1.5
It is about 50. The refractive index in the thickness direction is 1.60 or more,
Preferably, it is 1.61 or more. The upper limit is not particularly limited, but is about 1.63.

In the process of stretching, for example, the amount of heat of the infrared heater immediately before stretching is different between the front and back of the support, and if there is a temperature difference between the front and back of the support, the results are obtained when the support is biaxially stretched and heat-fixed. As a result, a difference in refractive index between the front and back of the support in the thickness direction occurs, and a flat support cannot be obtained. Even in the process of transverse stretching and heat setting, when the wind speed of the stenter upper and lower nozzles or the set temperature above and below the stenter changes, the difference in the refractive index in the thickness direction between the front and back of the support also occurs.

Needless to say, in addition to the sequential biaxial stretching method, the sequential biaxial stretching method of transverse / longitudinal stretching, transverse / longitudinal / longitudinal stretching method, longitudinal / transverse / longitudinal stretching method and the like can be applied. .

When a biaxially stretched and heat-fixed support is used, the difference in the refractive index between the front and back of the support in the thickness direction should be 4 × 10 ⁻³ or less, preferably 2 × 10 ⁻³ or less.

The biaxially oriented SPS-based support according to the present invention comprises:
It is not limited to those obtained by the method described above.

The SPS-based stretched support thus obtained is used for photographic light-sensitive materials (color, X-ray, printing sensitive material, etc.), magnetic recording (audio, video, floppy, etc.), and electrical (capacitor). , Electrical insulation materials, etc.) and vapor deposition applications (stamping, metallizing, etc.). The thickness is not particularly limited, but is 3 to 35.
It is useful for those having a thickness of 0 μm, but especially when the thickness of the support is increased, the difference in refractive index in the thickness direction becomes remarkable.
It is useful for those with a thickness of μm or more.

[0038]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The evaluation method of the support is shown below.

(1) Refractive Index in Thickness Direction The biaxially oriented SPS-based support of the present invention was measured for its refractive index on its front and back sides, and the refractive index for each thickness direction was determined.

Since it is necessary to define the front surface and the back surface of the support, it is handled as follows. That is, when the molten polymer is cooled and solidified on the casting drum, the surface in contact with the drum side is the D surface and the opposite surface is the A surface, and the refractive index in the thickness direction measured on the D surface side is nz (D), A the refractive index in the thickness direction measured at side and nz (a), shown as the difference between the refractive index in the thickness direction _{(Δn z) = nz (D} ) -nz (a).
The refractive index is measured by using an Abbe refractometer, using α-bromonaphthalene as an intermediate liquid, and measuring Na at 25 ° C.
Indicates the value for the line.

(2) Curling curl Curling curl refers to curling in the longitudinal direction when the curl is released from the core after being wound around the core. A biaxially oriented SPS-based support having a sample size of 12 cm (longitudinal direction during manufacturing) × 35 mm (horizontal direction during manufacturing) was used as a sample at 23 ° C. and 55% RH for 1 day. After controlling the humidity, the core was wound around a core having a diameter of 10.8 mm with the D side inside, and heat-treated for 4 hours in an atmosphere of 55 ° C. and 20% RH. The curl curl test conditions roughly correspond to the condition after 2 years storage when the support was wound on a core having a diameter of 3 inches.

Then, after allowing to cool in an atmosphere of 23 ° C. and 55% RH for 30 minutes, it was released from the core, and after 1 minute, the side surface of this support piece was erected on a horizontal plane, and D
The curling curl generated with the surface side inside is expressed as + (plus). Therefore, when curling with the A side as the inside, the curl degree is curled with a minus (-).
It is represented by 1 / R (m ^-1 ). This R represents the radius of curvature of the curled support, and the unit is m (meter). The curl degree when the curl is equal to that of a winding core having a maximum diameter of 10.8 mm (that is, a radius of curvature of 0.0054 m), 185.
2 (m ⁻¹ ), which is the worst and the support has a flat surface, the radius of curvature becomes infinite and the curl degree becomes 0 (m ⁻¹ ). Therefore, the smaller the value of the degree of curl, the better.

The flatness evaluation results were evaluated according to the following criteria.

⊚: The support is extremely flat, and the dimensional accuracy is not affected by the coating process (undercoating layer coating, emulsion layer coating, magnetic layer coating, etc.), slitting, punching process. ○: In the same process The curl of the support became a little worrisome, and the support take-up tension in the process was increased to allow it to be used without problems. X: The curl of the support was too tight, a problem occurred in the above process, and the product could not be used.

Example 1 (1) Polymerization of SPS polymer SPS pellets were prepared according to JP-A-3-131843. From the preparation of the catalyst to the polymerization reaction, all were carried out under a dry argon stream. In a glass container having an internal volume of 500 ml, 17.8 g of copper sulfate pentahydrate (CuSO ₄ .5H ₂ O) (7
(1 mmol) 200 ml of purified benzene and 24 ml of trimethylaluminum were added, and the mixture was stirred at 40 ° C. for 8 hours to adjust the catalyst. This was placed under an argon gas flow. After filtering through 3 glass filters, the filtrate was freeze-dried. This was taken out, placed in a 2 liter stainless steel container, and tributylaluminum and pentacyclopentadiethyl titanium methoxide were further mixed therein and heated to 90 ° C. 1 liter and 75 ml of purified styrene and 4-methylstyrene were put therein, and the polymerization reaction was continued at this temperature for 8 hours. After this, cool to room temperature and
The catalyst was deactivated by adding liter of methylene chloride and adding methanol solution of sodium methylate with further stirring. The content was gradually dropped into 20 liters of methanol, filtered through a glass filter, washed with methanol three times, and then dried. The weight average molecular weight of this polymer was 280,000, which was determined from the measurement results of GPC measured with standard polystyrene at 135 ° C. using 1,2,4-trichlorobenzene as a solvent. Further, the melting point of this polymer was 245 ° C., and it was confirmed by measurement of ¹³ C-NMR that the polymer had a syndiotactic structure. This was pelletized with an extruder to secure the required amount.

(2) Formation of SPS-based support film The obtained SPS-based polymer pellets were dried at 150 ° C. for 3 hours in a nitrogen atmosphere and melt-extruded at 330 ° C. from a T-die into a support-like form. On the cooling drum in which the support sheet is kept at 15 ° C. by the electrostatic application method, from the non-contact surface of the casting drum, the difference in cooling rate between the surface in contact with the casting drum and the surface not in contact with the casting drum is minimized. While applying cooling air, it was rapidly solidified to prepare an unstretched support having a thickness of about 930 μm. The cooling rate at which the molten polymer was rapidly cooled and solidified on the casting drum was 15 ° C / sec. This unstretched support was stretched 3.0 times in the longitudinal direction and 3.1 times in the transverse direction at a temperature of 105 ° C. between rolls having a speed difference of 245 ° C.
Then, it was heat set for 10 seconds, cooled at 85 ° C. for 10 seconds and wound up to obtain a biaxially oriented SPS-based support having a thickness of 100 μm.
Subsequent to this, the method described in Japanese Patent Application No. 7-221999, that is, the syndiotactic polystyrene support wound in a roll is heat treated at 85 ° C. for 48 hours to remove curling curl. Then, this biaxially oriented SPS
The curl degree of the system support was measured according to the above-mentioned measuring method.

Example 2 (1) Polymerization of SPS polymer In the same manner as in Example 1, a required amount of SPS polymer was secured.

(2) Formation of SPS-based support film The obtained SPS-based polymer pellets were dried at 150 ° C. for 3 hours in a nitrogen atmosphere, and melt-extruded at 330 ° C. into a support form from a T-die. On the cooling drum in which the support sheet is kept at 20 ° C. by the electrostatic application method, from the non-contact surface of the casting drum, the difference in cooling rate between the surface contacting the casting drum and the surface not contacting the casting drum is minimized. While applying cooling air, it was rapidly solidified to prepare an unstretched support having a thickness of about 930 μm. The cooling rate at which the molten polymer was rapidly cooled and solidified on the casting drum was 12 ° C / sec. This unstretched support was stretched 3.0 times in the longitudinal direction and 3.1 times in the transverse direction at a temperature of 105 ° C. between rolls having a speed difference of 245 ° C.
Then, it was heat set for 10 seconds, cooled at 85 ° C. for 10 seconds and wound up to obtain a biaxially oriented SPS-based support having a thickness of 100 μm.
Subsequent to this, the method described in Japanese Patent Application No. 7-221999, that is, the syndiotactic polystyrene support wound in a roll is heat treated at 85 ° C. for 48 hours to remove curling curl. Then, this biaxially oriented SPS
The curl degree of the system support was measured according to the above-mentioned measuring method.

Comparative Example 1 (1) Polymerization of SPS Polymer In the same manner as in Example 1, the required amount of SPS polymer was secured.

(2) Formation of SPS-based support film The obtained SPS-based polymer pellets were dried at 150 ° C. for 3 hours in a nitrogen atmosphere and melt-extruded at 330 ° C. from a T-die into a support-like form. The support sheet was rapidly cooled and solidified on a cooling drum at 15 ° C. by an electrostatic application method to give a thickness of about 9
An unstretched support of 30 μm was prepared.

In order to quench and solidify the drum surface side, the cooling air on the surface not in contact with the drum surface was stopped. The cooling rate at which the molten polymer was rapidly cooled and solidified on the casting drum was 8 ° C / sec. This unstretched support was subjected to 3.0% in the machine direction at 105 ° C. between rolls having a speed difference.
Double stretching 3.1 times in the transverse direction, heat setting at 245 ° C for 10 seconds, cooling at 85 ° C for 10 seconds, and winding to obtain a thickness of 100
A μm biaxially oriented SPS-based support was obtained. Subsequently, the method described in Japanese Patent Application No. 7-221999, that is, the syndiotactic polystyrene type support wound in a roll shape is heat treated at 85 ° C. for 48 hours to remove curling curl. The curl degree of this biaxially oriented SPS-based support was measured according to the above-described measuring method.

Comparative Example 2 (1) Polymerization of SPS Polymer In the same manner as in Example 1, the required amount of SPS polymer was secured.

(2) Formation of SPS-based support film The obtained SPS-based polymer pellets were dried at 150 ° C. for 3 hours in a nitrogen atmosphere, and melt-extruded at 330 ° C. into a support form from a T-die. The support sheet was rapidly cooled and solidified on a cooling drum at 25 ° C. by an electrostatic application method to give a thickness of about 9
An unstretched support of 30 μm was prepared.

A biaxially oriented SPS-based support was obtained in the same manner as in Example 1 except that the cooling rate of this unstretched support was 7 ° C./sec. Subsequently, the method described in Japanese Patent Application No. 7-221999, that is, the syndiotactic polystyrene type support wound in a roll shape is heat treated at 85 ° C. for 48 hours to remove curling curl. The curl degree of this biaxially stretched support was measured according to the above-described measuring method.

Comparative Example 3 (1) Polymerization of SPS Polymer In the same manner as in Example 1, a required amount of SPS polymer was secured.

(2) Formation of SPS-based support film The obtained SPS-based polymer pellets were dried at 150 ° C. for 3 hours in a nitrogen atmosphere and melt-extruded at 330 ° C. from a T-die into a support-like form. The support sheet was rapidly cooled and solidified on a cooling drum at 35 ° C. by an electrostatic application method to give a thickness of about 9
An unstretched support of 30 μm was prepared.

The unstretched support was cooled at a cooling rate of 5 ° C./sec. Further, when the unstretched support is longitudinally stretched between rolls having a speed difference, the surface A side is heated by an infrared heater only from the side A so that the surface temperature becomes 110 ° C. The surface temperature of the D side was 65 ° C., and the film was stretched 3.0 times in the machine direction. The obtained longitudinal uniaxially stretched SPS-based support had a tendency to curl to the D surface side. Furthermore, by the tenter, it is 3.1 in the lateral direction.
Double stretching, followed by heat setting at 245 ° C. for 10 seconds, 85
After cooling at 10 ° C. for 10 seconds and winding, a biaxially oriented SPS-based support having a thickness of 100 μm was obtained. Subsequently, Japanese Patent Application No. 7-22
The method described in 1999, that is, a syndiotactic polystyrene-based support wound in a roll is
Heat treatment at ℃ for 48 hours to remove curling curl,
The curl degree of this biaxially oriented SPS-based support was measured according to the above-described measuring method.

[0058]

[Table 1]

From the above results, it is understood that the film of the present invention is extremely excellent in flatness.

[0060]

EFFECT OF THE INVENTION By setting the difference in refractive index between the front and back sides of the SPS film in the thickness direction to be 4 × 10 ⁻³ or less, the support is transparent, has excellent surface flatness, and has little curl, and is a support for SPS photographic light-sensitive materials. I was able to get

Claims (2)

[Claims] 1. A support comprising a syndiotactic polystyrene-based polymer, which is oriented and heat-fixed in both vertical and horizontal directions, the difference in refractive index (Δ) between the front and back of the support.
n _Z ) is 4 × 10 ⁻³ or less, a support for a photographic light-sensitive material. 2. The support for a photographic light-sensitive material according to claim 1, wherein the difference (Δn _Z ) in the refractive index between the front and the back of the support in the thickness direction is 2 × 10 ⁻³ or less.