JP2003220639A - Polystyrene resin foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polystyrene-based resin foam having good paper interleaving property using a water-based paste or the like generally used in the past, and to prevent the adhered paper from peeling off, and a method for producing the same. SOLUTION: The polystyrene-based resin foam is in the form of a plate or a sheet, and has a skin layer on the outermost surface thereof.
The number of concave portions less than 0 μm is 20 // 4m per unit area.
m ² or more. In the production method, a polystyrene resin having a predetermined melt tension is extruded and foamed into a cylindrical shape, and after cooling, the cylinder is crushed and laminated in two layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-like or sheet-like polystyrene resin foam produced by, for example, a fusion method, and a method for producing the same.

[0002]

2. Description of the Related Art One of methods for producing a plate-shaped or sheet-shaped polystyrene resin foam having a predetermined thickness is as follows.
There is a fusion-bonding method in which a polystyrene-based resin foam extruded and foamed into a cylindrical shape is crushed by passing it through a pinch roll immediately after extrusion so as to be superposed and fused in two layers. According to such a fusion bonding method, a large-sized plate-shaped or sheet-shaped polystyrene resin foam having a thickness twice that of the usual extrusion method can be manufactured inexpensively and in large quantities. Therefore, the polystyrene-based resin foam produced by the fusion method is widely used as a base material for large-sized panels and the like in the fields of commercial advertisement, graphic design, graphic art, and the like.

When a polystyrene resin foam is used as a base material for a panel, it is common to paste a design-printed paper on the surface of the foam. For the sizing, an aqueous type sizing agent such as a vinyl acetate emulsion is used.

[0004]

However, the conventional polystyrene-based resin foams have insufficient adhesiveness (generally referred to as "interleaving property") of the paper by the above-mentioned glue, and in particular, the floating of the paper at the edge portion may occur. It is apt to occur and the paper is easily peeled off. Therefore, an object of the present invention is to provide a novel polystyrene-based resin foam having good interleaving property of paper with a conventionally used aqueous glue or the like, and the bonded paper is difficult to peel off, and a manufacturing method thereof. .

[0005]

[Means for Solving the Problems] The interleaving property between dissimilar materials such as a combination of a polystyrene resin and a water-based adhesive constitutes the surface, that is, the surface of a polystyrene resin foam in this case. The chemical condition of the surface of the epidermis,
In particular, the chemical affinity for the glue and the physical condition of the surface of the skin layer are greatly related. Of these, as the latter physical state, the surface shape of the skin layer, in particular, the concave portion is important, and it is known that the concave portion contributes to improve the interleaf paper property by the so-called anchor effect.

However, in order to change the chemical state of the surface of the skin layer of the polystyrene resin foam in order to improve the interleaving property, it is necessary to perform plasma treatment or flame treatment on the skin layer. In addition to the increase in the amount, it takes time and labor to manufacture, and these treatments may affect the density of the polystyrene-based resin foam and the surface shape of the skin layer. Therefore, the inventor has conducted a study focusing on the concave portion. That is, the surface of the skin layer of the polystyrene resin foam,
It was studied to form more recesses than ever and improve the interleaving property of the paper by the glue due to the anchor effect.

However, as a result of examination, it is not effective to simply increase the number of recesses, and the size of the opening of the recess is
It became clear that it was closely related to the improvement of the interleaf paper property. That is, the recesses with too small openings cannot exert the anchor effect because the water-based glue does not enter the inside. On the contrary, since the recesses that are too large are wide and shallow, the anchor effect cannot be exerted. Also, the larger the opening, the smaller the number of recesses per unit area, which cannot contribute to the improvement of the anchor effect.

Therefore, as a result of further study by the inventor of the size range of the opening of the recess and the range of the number of the recess per unit area which can exert a good anchor effect, the major axis of the opening is 25 μm or more and 100 μm. It was found that a polystyrene-based resin foam having 20/4 mm ² or more recesses per unit area has excellent interleaf paper properties due to an aqueous glue and has completed the present invention. . Therefore, the invention according to claim 1 is a plate-shaped or sheet-shaped polystyrene-based resin foam provided with a skin layer, wherein the surface of the skin layer has a recess having a major axis of opening of 25 μm or more and less than 100 μm. , 20 per unit area
It is a polystyrene-based resin foam characterized by having a ratio of 4/4 mm ² or more.

[0009] The inventors of the present invention have found that various polystyrene-based resin foams produced by the fusion method, which are commercially available and have insufficient paper interleaving properties with glue, have the number of recesses whose major axis of opening is within the above range. As a result of counting
The number was about / 4 mm ² . The inventor has also studied a method for producing the polystyrene resin foam of the present invention. As a result, when the melt tension of the polystyrene-based resin used in the above-mentioned fusion method is made smaller than before, and the amount of elongation of the resin at the foaming suitable temperature is increased, the skin layer has a large number of elongations with a large elongation. It was found that a recess was formed. Therefore, the inventors have, without made different to conventional extrusion foaming conditions of too, the number of recesses major axis of the opening is within the range of the 20 per unit area / 4 mm ²
The present invention has been completed as a result of studying an appropriate range of melt tension in order to increase the above.

Therefore, the invention according to claim 6 is a method for producing the polystyrene resin foam according to claim 1, wherein the melt tension at 200 ° C. is 39.2 to 107.
Including a step of extruding and foaming a polystyrene resin of 8 mN into a cylindrical shape, a step of cooling the outer surface of the cylinder immediately after extrusion, and a step of crushing the cooled cylinder and superimposing it in two layers and fusing them together. A method for producing a characteristic polystyrene-based resin foam.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below. <Polystyrene Resin Foam> The polystyrene resin foam of the present invention is a plate-like or sheet-like product having a skin layer, and has a large number of recesses on the surface of the skin layer. Of these, the major axis of the opening is 25 μm or more and 100
Recesses that are less than μm (hereinafter referred to as "recesses with a specific major diameter")
At a rate of 20/4 mm ² or more per unit area.

In the present invention, the major axis of the opening which defines the number is limited within the above range because the major axis of the opening is 25 μm.
As described above, the small recesses having a diameter of less than m do not allow the aqueous glue to enter therein, and the large recesses having the major axis of the opening of 100 μm or more are also wide and shallow as described above. This is because the anchor effect cannot be exhibited in any case. Therefore, in the present invention, the number of recesses whose major axis of the opening is out of the above range is not limited, and any number of recesses may be provided, or conversely, none may be provided. However, a large recess of 100 μm or more causes deterioration of the surface roughness and causes a decrease in the slip sheet property.
It is desirable to have as few as possible.

On the other hand, when the number of the recesses having the specific major axis within the range of the major axis of the opening being 25 μm or more and less than 100 μm is less than 20/4 mm ² , the interleaving property of the paper by the glue is enhanced by the anchor effect. The effect cannot be obtained, and the adhered paper cannot be prevented from peeling off. Therefore, the number of recesses having a specific major axis is limited to 20/4 mm ² or more.
In consideration of further improving the paper interleaving property of the glue, it is preferable that the number of the concave portions having the specific major axis is 40 pieces / 4 mm ² or more even within the above range.

However, if there are too many recesses,
There is a possibility that the amount of glue absorbed in the recesses increases, and the interleaving property of the paper due to the glue deteriorates. To prevent this, a large amount of glue may be required. Therefore, in view of improving the paper interleaving property of the glue without using a large amount of glue, it is preferable that the number of the concave portions having the specific major axis is 100 or less even within the above range. Other properties of the polystyrene-based resin foam are not particularly limited, but the ratio of the total area of openings of all the recesses (opening ratio) occupying the surface of the skin layer is 1% or more and less than 10%. Is preferred. If the opening ratio is less than 1%, the anchor effect will be insufficient. Further, when the opening ratio is 10% or more, the amount of glue absorbed in the recesses increases, so that the interleafability of the paper is deteriorated and the paper may be easily peeled off. The opening ratio is particularly preferably 3 to 6% within the above range.

The surface roughness of the surface layer is preferably 2 to 10 μm in terms of center line average roughness Ra. When the center line average roughness Ra is less than 2 μm, the individual concave portions are too shallow, so that the anchor effect is not sufficiently exerted and the paper interleaving property due to the adhesive may be deteriorated. When the center line average roughness Ra exceeds 10 μm, the individual recesses are too deep, and the amount of glue absorbed in the recesses increases, which may reduce the paper interleaving property of the glue. The centerline average roughness Ra of the surface of the skin layer is 3 to 8 μm even within the above range.
It is preferably m.

The average cell diameter inside the foam is preferably 0.4 mm or less. When the average bubble diameter exceeds 0.4 mm, the surface roughness of the surface layer exceeds the above range, and the amount of glue absorbed in the recesses increases, so the paper interleaving property of the glue decreases. There is a risk. The average bubble diameter is
Even within the above range, it is particularly preferably 0.1 to 0.3 mm. The open cell ratio inside the foam is preferably 15% or less. If the open cell ratio exceeds 15%, the compressive strength may decrease, and the thickness recovery performance due to compression may deteriorate. The open cell rate is preferably 10% or less, even within the above range.

Further, the total density of the polystyrene resin foam is preferably 0.05 to 0.12 g / cm ³ . When the density is less than 0.05 g / cm ³ , the strength of the polystyrene-based resin foam is insufficient, and there is a possibility that it cannot be used as a base material for a large panel or the like. On the other hand, if the density exceeds 0.12 g / cm ³ , the polystyrene resin foam becomes too heavy, and the advantage of lightness cannot be utilized. It also leads to higher costs. The density is preferably 0.05 to 0.07 g / cm ³ even within the above range.

<Method for producing polystyrene resin foam>
The polystyrene-based resin foam can be manufactured by various conventionally known methods, but it is particularly preferably manufactured by a fusion method. In the fusion method, polystyrene-based resin is extruded and foamed into a cylindrical shape, the outer surface of the cylinder immediately after extrusion is cooled, and then the cooled cylinder is crushed, and the polystyrene-based resin foam is fused by superposing in two layers. Is manufactured.

At this time, when a polystyrene resin having a melt tension at 200 ° C. of 39.2 to 107.8 mN is used as the raw material, the polystyrene resin foam of the present invention can be obtained. When the melt tension at 200 ° C. of the polystyrene resin is less than 39.2 mN, the melt tension is too small, and the amount of elongation of the resin at the foaming suitable temperature becomes too large. For this reason, the number of recesses formed in the skin layer becomes too large, or the number of recesses having a specific major axis is reduced as a result of the number of recesses having a large diameter of the openings of 100 μm or more, which is rather reduced. A polystyrene resin foam cannot be obtained.

If the melt tension is too low as described above, the foam extruded from the mold hangs down by its own weight during the production by the fusion method, and the cylindrical shape before fusion is deformed. As a result, it is not possible to obtain a plate-shaped body having no difference in front and back. Further, the melt tension of the polystyrene resin at 200 ° C. is 10
When it exceeds 7.8 mN, since the melt tension is too high, the elongation of the resin at the foaming suitable temperature becomes insufficient,
As a result of the decrease in the number of recesses having a specific major axis formed in the skin layer, the polystyrene resin foam of the present invention cannot be obtained. In addition, in the fusion method, the width of the polystyrene resin foam is adjusted by injecting air and inflating it like a balloon until the extrusion foamed cylinder is crushed through a pinch roll. If the tension is excessively large, there is a problem that it is difficult to obtain a sufficient width in this step.

The melt tension of the polystyrene resin at 200 ° C. is especially 49.0 to 7 even within the above range.
It is preferably 8.4 mN. Other characteristics of the polystyrene resin are not particularly limited, but the melt flow rate MFR is preferably 4 to 10 g / 10 min. If the MFR is less than 4 g / 10 min, the elongation of the resin at the foaming suitable temperature may be insufficient. On the other hand, when the MFR exceeds 10 g / 10 min, the melt tension of the foam decreases, so that the amount of elongation of the resin at the foaming suitable temperature becomes too large. As a result, the number of recesses having a specific major axis may decrease. The MFR is preferably 5 to 8 g / 10 min even within the above range.

The conditions of the fusion method in the above steps may be the same as conventional ones. However, in the fusion method, usually, the outer surface of the cylinder immediately after extrusion is cooled by blowing air, but in the present invention,
The amount of air blown is, for example, in the case of air of 30 to 40 ° C., 0.005 to 0.07 m ³ per 1 m ^{2 of} the outer surface.
Is preferable. The amount of air blown is 0.
If it is less than 005 m ³ / m ² , the cooling is insufficient, the thickness of the skin layer generated by cooling is too small, and the strength is too low, so it may be easily scratched when crushed through pinch rolls, and the commercial value may be reduced. There is.

The amount of air blown is 0.07 m ³ /
When it exceeds m ² , the cooling is excessive, and the thickness of the skin layer formed by cooling becomes too large, so that a predetermined number and number of recesses may not be formed on the surface of the skin layer. The amount of air blown at 30-40 ° C is
Even within the above range, especially 0.007 to 0.06 m ³ / m ²
Is preferred. By setting the temperature of the air and the blowing amount within the above range, the air can be uniformly blown to the foam.

<Polystyrene Resin> As the polystyrene resin, any of various styrene resins having the above-mentioned characteristics can be used. Examples of such polystyrene resins include homopolymers or copolymers of styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, vinyltoluene and vinylxylene.

Copolymers of these styrene-based monomers with other vinyl monomers can also be used. Examples of other vinyl monomers include acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, maleic anhydride, acrylamide and the like. Further, if the polystyrene-based resin is the main component, a mixed resin obtained by adding and mixing another resin can also be used. As the mixed resin, for example, in order to improve the impact resistance of the foam, a polyene, a styrene-butadiene copolymer, an ethylene-propylene-a non-conjugated diene terpolymer such as a diene rubbery polymer. Examples of the rubber-modified polystyrene-based resin added, so-called high-impact polystyrene, and the like.

<Foaming Agent> As the foaming agent for extruding and foaming the polystyrene resin, various volatile foaming agents and decomposable foaming agents can be mentioned. Among them, examples of the volatile foaming agent include hydrocarbons such as propane, butane and pentane, and halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane and difluoroethane.
Examples thereof include two or more kinds, and butane is particularly preferably used. As butane, normal butane or isobutane may be used alone, or normal butane and isobutane may be used in an optional ratio.

As the decomposing type foaming agent, for example, an organic foaming agent such as azodicarbonamide or dinitrosopentamethylenetetramine, an organic acid such as citric acid or a salt thereof, and a bicarbonate such as sodium bicarbonate are combined. Inorganic foaming agents such as In some cases,
Carbon dioxide, nitrogen, water, etc. can also be used appropriately.
These foaming agents can be used alone or in combination of two or more.

<Foam Nucleating Agent> Examples of the foam nucleating agent include talc and calcium stearate. The foam nucleating agent is 0.5 with respect to 100 parts by weight of the polystyrene resin.
~ 5.0 parts by weight are added. <Other additives> Polystyrene-based resins include foaming agents,
Various additives other than the foam nucleating agent may be added. Other additives that can be added to the polystyrene resin include, for example, ultraviolet absorbers, antioxidants, colorants, lubricants, flame retardants, antistatic agents, and the like. The blending ratio of the additive is appropriately set.

[0029]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. The properties of the polystyrene-based resins used in Examples and Comparative Examples of the present invention and the produced polystyrene-based resin foams were measured by the following methods. <Polystyrene resin> (Measurement of melt tension) The melt tension of polystyrene resin is
Measuring device manufactured by Toyo Seiki Co., Ltd. [Capirograph P
MD-C] was used for measurement as follows.

First, a polystyrene resin as a sample is
After being heated to 200 ° C. and melted, it was made to flow into the cylinder of the above apparatus, and then a capillary (diameter 1 mm, length 10 mm, shown in FIG.
Resin inflow angle from cylinder to capillary θ = 9
From 0 °), it was extruded in a string shape while keeping the extrusion speed at a constant speed of 100 mm / min. Next, after passing this string-like object through the tension detecting pulley arranged below the nozzle, the winding speed is set to 12 by using a winding roll.
It was set to m / min and wound up.

The maximum tension detected by the tension detecting pulley when the tape was wound until it was cut was taken as the melt tension (mN) of the polystyrene resin. MFR of polystyrene resin (Measurement of MFR) is in accordance with the test method Shosai in Japanese Industrial Standard JIS K7210 _-1999, was measured as follows.

An extrusion type plastometer (capillary rheometer) conforming to the same standard was used as a measuring device.
And test temperature θ = 200 ° C., nominal load (combination) M
_When polystyrene resin is extruded under the condition of _nom = 5.00 kg, MF is calculated from the distance and time the piston has moved.
R (g / 10min) was calculated. <Polystyrene-based resin foam> (Counting the recesses on the surface of the skin layer and calculating the aperture ratio) An enlarged photograph of the surface of the skin layer of the polystyrene-based resin foam (magnification: 40 times) is taken by a scanning electron microscope [Co., Ltd.]. The image was taken using S-3000N manufactured by Hitachi, Ltd.]. And on the photo,
The major axis of all recesses in the area of ² mm square (= 4 mm ² ) in actual size was measured, and the major axis was 25 μm or more, 1
The number of concave portions having a specific major axis of less than 00 μm was determined.

Photographing was carried out at arbitrary three points on the polystyrene resin foam, and the number of the recesses of the specified major axis at each position thus obtained was arithmetically averaged (rounded off to the right of the decimal point) to obtain the polystyrene resin foam. It was defined as the number of concave portions having a specific major axis in the body (number / 4 mm ² ). In addition, among the photographic papers printed with the above photographs, the above-mentioned actual dimensions are 2 mm square (= 4 mm
^After the area ² ) was cut out and its weight A (g) was weighed, all the concave portions shown therein were cut out and the total weight B (g) was weighed. Then, the ratio of the total area of the openings of all the recesses on the surface of the skin layer, that is, the opening ratio (%) was determined by the formula: opening ratio (%) = B / A × 100.

(Measurement of Surface Roughness) Using a surface roughness measuring instrument [Handysurf E-30A] manufactured by Tokyo Seimitsu Co., Ltd., a polystyrene resin was prepared under the conditions of a cutoff value of 0.8 mm and a measurement length of 4 mm. The surface roughness of the surface layer of the foam was measured, and the centerline average roughness Ra was determined from the measured value. The measurement is
Extrusion direction (MD direction) of polystyrene resin foam,
In the direction orthogonal to that (TD direction), the values obtained by carrying out at arbitrary 5 points are arithmetically averaged to obtain the above M
The center line average roughness Ra (μm) in the D direction and the TD direction was used.

(Measurement of Average Cell Diameter) The average cell diameter inside the polystyrene resin foam is determined by ASTM D2842.
It measured as follows according to the measuring method described in -69. First, the foam was cut along the MD direction and the TD direction, and an enlarged photograph of each cut surface was taken using a scanning electron microscope [S-3000N manufactured by Hitachi, Ltd.].

Next, a straight line (long line) provided at any position on the photographed photograph and extending in the MD and TD directions and in the thickness direction (VD direction) of the foamed body orthogonal to both directions (long direction). The number of bubbles above 60 mm) was counted, and the average chord length t of bubbles in the above three directions was determined by the following formula. Average chord length t = 60 / (number of bubbles × magnification of photograph) Then, by the following equation, average bubble diameter d (= φMD,
φTD or φVD) was determined.

Average Cellular System d (mm) = t / 0.616 (Measurement of Open Cell Rate) The internal open cell rate (%) of the polystyrene-based resin foam is determined by the air techno specified in ASTM D-2856. The measurement was performed according to the meter (air-comparison specific gravity meter) method (1-1 / 2-1 atmospheric pressure method). As the air-comparison type hydrometer, one manufactured by Toshiba Beckman Co., Ltd. was used.

(Measurement of Density) The density (g / cm ³ ) of the polystyrene resin foam was obtained by measuring the weight and the volume and calculating the weight (g) ÷ volume (cm ³ ). Example 1 A tandem extruder having a discharge rate of 240 kg / hr and an apparatus having a diameter of 170 attached to the tip of the extruder as an apparatus for producing a polystyrene resin foam by the fusion method.
mm, a circular die having an annular slit with a width of 1.0 mm, a pinch roll arranged at a position 115 cm ahead of the circular die in the resin extrusion direction, and an air arranged in this order between the circular die and the pinch roll. A ring and a guide roll, a take-up machine arranged in front of the pinch roll, and a cutting machine arranged in front of the take-up machine were prepared. Pinch roll clearance is 4mm,
The expansion degree of the guide roll from the pinch roll side is 55
The outside air temperature around the pinch roll and the guide roll was 33 ° C.

As a polystyrene resin, the melt tension at 200 ° C. is 56.8 mN and the MFR is 7.9 g / 10 mi.
n, the weight average molecular weight Mw is 187,000, and Mw /
Using polystyrene having a Mn of 2.5 (HRM-10N manufactured by Toyo Styrene Co., Ltd.), 1.0 part by weight of talc as a foam nucleating agent and 0.1 part by weight of calcium stearate per 100 parts by weight of this polystyrene. Parts were added and dry blended. Next, this mixture is supplied to a tandem type extruder of the above apparatus to be melted and kneaded, and then mixed butane of isobutane and normal butane (weight ratio 67:33) is used as a foaming agent to obtain 93.6% by weight of the above mixture. It was added and kneaded at a rate of 6.4 parts by weight per part.

Next, the cylinder temperature at the tip of the extruder is set to 85.
While adjusting the temperature of the molten mixture to 133 ° C by lowering it to ℃,
A cylindrical die was extruded and foamed through a circular die attached to the tip of the extruder. The tip temperature of the circular die was 110 ° C. Next, the cylinder immediately after extrusion foaming was cooled by blowing air of 35 ° C. from the outside through an air ring. The amount of air blown was 0.008 m ³ per 1 m ² of the outer surface of the cylinder.

Next, the cooled cylinder was squeezed through a guide roll and a pinch roll, two layers were superposed and fused, and then taken by a take-off machine and cut by a cutting machine to produce a polystyrene resin foam. The obtained polystyrene-based resin foam has a width of 800 mm and an average thickness of 4.9 m.
m (minimum thickness 4.8 mm, maximum thickness 5.0 mm) plate-shaped, the overall density is 0.056 g / cm ³ , the average bubble diameter inside is φMD = 0.29 mm, φTD = 0.28 m
m, φVD = 0.15 mm, open cell ratio is 8.0%, center line average roughness Ra of the skin layer surface is 5.6 μ in the MD direction.
m was 7.1 m in the TD direction.

The major axis of the opening on the surface of the skin layer is 25 μm.
of a concave portion having a specific major axis of at least m and less than 100 μm,
The number per unit area was 46/4 mm ² . An electron micrograph of the surface of the skin layer is shown in FIG. The aperture ratio was 6.2%. Example 2 A tandem extruder having a discharge rate of 240 kg / hr and an apparatus having a diameter of 170 attached to the tip of the extruder as an apparatus for producing a polystyrene resin foam by the fusion method.
mm, a circular die having an annular slit with a width of 1.0 mm, a pinch roll arranged 110 cm ahead of the circular die in the resin extrusion direction, and an air arranged in this order between the circular die and the pinch roll. A ring and a guide roll, a take-up machine arranged in front of the pinch roll, and a cutting machine arranged in front of the take-up machine were prepared. Pinch roll clearance is 4mm,
The expansion degree of the guide roll from the pinch roll side is 55
The outside air temperature around the pinch roll and the guide roll was 33 ° C.

As a polystyrene resin, the melt tension at 200 ° C. is 104.86 mN and the MFR is 6.0 g / 10.
min, weight average molecular weight Mw is 219000, and M
Polystyrene with w / Mn of 2.95 [Toyo Styrene
HRM-12N] manufactured by K.K.
To 100 parts by weight, 1.0 part by weight of talc as a foam nucleating agent and 0.1 part by weight of calcium stearate were added and dry blended.

Next, this mixture is supplied to a tandem type extruder of the above apparatus to be melted and kneaded, and then a mixed butane of isobutane and normal butane (weight ratio 6 is used as a foaming agent.
7:33) in an amount of 6.0 per 94.0 parts by weight of the above mixture.
The mixture was added at a ratio of parts by weight and further kneaded. Next, while the temperature of the cylinder at the tip of the extruder was lowered to 88 ° C. and the temperature of the molten mixture was adjusted to 140 ° C., it was extruded into a cylindrical shape through a circular die attached to the tip of the extruder.
The tip temperature of the circular die was 113 ° C.

Next, the cylinder immediately after extrusion foaming was cooled by blowing air at 35 ° C. from the outside through an air ring. The amount of air sprayed is 1 m ^{2 on} the outer surface of the cylinder.
It was set to 0.058 m ³ . Next, the cooled cylinder was crushed through a guide roll and a pinch roll, and 2
The layers were superposed on each other and fused, and then taken out by a take-off machine and cut by a cutting machine to produce a polystyrene resin foam.

The obtained polystyrene resin foam has a width of 640 mm and an average thickness of 5.0 mm (minimum thickness 4.9 m).
m, the maximum thickness is 5.1 mm), the overall density is 0.067 g / cm ³ , and the average bubble diameter inside is φMD =
0.34 mm, φTD = 0.38 mm, φVD = 0.2
0 mm, open cell ratio 10.3%, center line average roughness Ra of the skin layer surface is 3.5 μm in the MD direction, and 5. in the TD direction.
It was 0 μm. The major axis of the opening on the surface of the skin layer is 2
The number of concave portions having a specific major axis of 5 μm or more and less than 100 μm per unit area was 25/4 mm ² . An electron micrograph of the surface of the skin layer is shown in FIG. The aperture ratio was 1.6%.

Comparative Example 1 A tandem extruder having a discharge rate of 240 kg / hr as a device for producing a polystyrene resin foam by a fusion method, and a diameter 153 attached to the tip of this extruder.
mm, a circular die having an annular slit of 1.3 mm in width, a pinch roll arranged at a position 105 cm ahead of the resin in the resin extrusion direction of this circular die, and an air arranged in this order between the circular die and the pinch roll. A ring and a guide roll, a take-up machine arranged in front of the pinch roll, and a cutting machine arranged in front of the take-up machine were prepared. Pinch roll clearance is 4mm,
The expansion degree of the guide roll from the pinch roll side is 55
The outside air temperature around the pinch roll and the guide roll was 33 ° C.

As a polystyrene resin, the melt tension at 200 ° C. is 127.4 mN, and the MFR is 1.8 g / 10 m.
in, weight average molecular weight Mw is 341,000, and Mw
/ Mn is 3.5 [G-made by A & M Co.
9305], 0.5 part by weight of talc as a foam nucleating agent and 0.04 part by weight of magnesium stearate were added to 100 parts by weight of this polystyrene and dry blended. Next, this mixture is supplied to a tandem type extruder of the above apparatus to be melted and kneaded, and then a mixed butane of isobutane and normal butane (weight ratio 3
5:65) to 6.0 per 94.0 parts by weight of the above mixture.
The mixture was added at a ratio of parts by weight and further kneaded.

Next, the cylinder temperature at the tip of the extruder is set to 90.
While adjusting the temperature of the molten mixture to 146 ° C by lowering it to
A cylindrical die was extruded and foamed through a circular die attached to the tip of the extruder. The tip temperature of the circular die was 115 ° C. Next, the cylinder immediately after extrusion foaming was cooled by blowing air of 35 ° C. from the outside through an air ring. The amount of air blown was 0.072 m ³ per 1 m ² of the outer surface of the cylinder.

Next, the cooled cylinder was crushed through a guide roll and a pinch roll, two layers were superposed and fused, and then taken out by a take-off machine and cut by a cutting machine to produce a polystyrene resin foam. The obtained polystyrene resin foam has a width of 640 mm and an average thickness of 4.9 m.
m (minimum thickness 4.8 mm, maximum thickness 5.0 mm) plate-shaped, the overall density is 0.067 g / cm ³ , the average bubble diameter inside is φMD = 0.41 mm, φTD = 0.35 m
m, φVD = 0.18 mm, open cell rate 14.7%,
The centerline average roughness Ra of the surface of the epidermis layer is 3.4 μ in the MD direction.
m and TD direction was 5.5 μm.

The major axis of the opening on the surface of the skin layer is 25 μm.
of a concave portion having a specific major axis of at least m and less than 100 μm,
The number per unit area was 0/4 mm ² . An electron micrograph of the surface of the skin layer is shown in FIG. The aperture ratio was 0%. Comparative Example 2 A tandem extruder having a discharge rate of 240 kg / hr as a device for producing a polystyrene resin foam by a fusion method, and a diameter 170 attached to the tip of the extruder.
mm, a circular die having an annular slit with a width of 1.0 mm, a pinch roll arranged 110 cm ahead of the circular die in the resin extrusion direction, and an air arranged in this order between the circular die and the pinch roll. A ring and a guide roll, a take-up machine arranged in front of the pinch roll, and a cutting machine arranged in front of the take-up machine were prepared. Pinch roll clearance is 4mm,
The expansion degree of the guide roll from the pinch roll side is 55
The outside air temperature around the pinch roll and the guide roll was 33 ° C.

As a polystyrene resin, the melt tension at 200 ° C. is 104.86 mN, and the MFR is 6.0 g / 10.
min, weight average molecular weight Mw is 219000, and M
Polystyrene with w / Mn of 2.95 [Toyo Styrene
HRM-12N] manufactured by K.K.
To 100 parts by weight, 1.1 parts by weight of talc as a foam nucleating agent and 0.06 part by weight of calcium stearate were added and dry blended.

Next, this mixture is fed to a tandem type extruder of the above apparatus and melted and kneaded, and then mixed butane of isobutane and normal butane (weight ratio 6 is used as a foaming agent.
7:33) to 5.2 per 94.8 parts by weight of the above mixture.
The mixture was added at a ratio of parts by weight and further kneaded. Next, while the temperature of the cylinder at the tip of the extruder was lowered to 88 ° C. to adjust the temperature of the molten mixture to 145 ° C., it was extruded and foamed into a cylindrical shape through a circular die attached to the tip of the extruder.
The tip temperature of the circular die was 110 ° C.

Next, the cylinder immediately after the extrusion and foaming was cooled by blowing 35 ° C. air from the outside through an air ring. The amount of air sprayed is 1 m ^{2 on} the outer surface of the cylinder.
It was set to 0.082 m ³ . Next, the cooled cylinder was crushed through a guide roll and a pinch roll, and 2
The layers were superposed on each other and fused, and then taken out by a take-off machine and cut by a cutting machine to produce a polystyrene resin foam.

The obtained polystyrene resin foam has a width of 800 mm and an average thickness of 5.0 mm (minimum thickness 4.9 m).
m, the maximum thickness is 5.1 mm), the overall density is 0.074 g / cm ³ , and the average bubble diameter inside is φMD =
0.30 mm, φTD = 0.35 mm, φVD = 0.1
4 mm, open cell ratio 11.4%, center line average roughness Ra of the skin layer surface is 3.5 μm in the MD direction, and 5. in the TD direction.
It was 2 μm. The major axis of the opening on the surface of the skin layer is 2
The number of concave portions having a specific major axis of 5 μm or more and less than 100 μm per unit area was 10/4 mm ² . An electron micrograph of the surface of the skin layer is shown in FIG. The aperture ratio was 0.7%.

<Synthetic Paper Test> After applying a glue with a glue roller on one side of the polystyrene resin foams produced in the above Examples and Comparative Examples, a coated paper having a basis weight of 135 g / m ² was placed and passed through a pressure roller. Pasted together The amount of glue applied is 1
Two types were used, 5 g / m ² and 10 g / m ² . The coating amount was determined by calculating the weight of the adhesive from the total weight of the paper and the foam, which had been measured in advance, and the weight of the laminate immediately after they were bonded, and dividing the weight by the bonding area.

As the paste, a vinyl acetate emulsion-based Lifebond AV-740LH (manufactured by Niei Kako Co., Ltd.)
Was diluted with 5% water. The number of samples was 10 for each of the two types of coating amounts in each of the examples and comparative examples. The interleaving property was evaluated by visually observing the sample immediately after bonding and visually observing the following criteria.

◯: All samples are stuck without any problem. Good interleaf paper property. B: Almost adhered, but floating of paper was seen in some samples. Interleaf paper is slightly defective. X: In most of the samples, floating of the paper was observed at the edges. Poor interleaf paper. Next, after each sample was left for one day, an attempt was made to peel off the paper by hand, and then the samples were evaluated according to the following criteria.

◯: All the samples adhered well and were difficult to peel off. If they were forcibly peeled off, the paper was torn or the surface of the foam was broken. Good interleaf paper property. Δ: Although adhered, the paper and the foam were peeled cleanly and easily when peeled by hand. Interleaf paper is slightly defective. X: A part which was not adhered at all was observed. Poor interleaf paper. The above results are summarized in Table 1.

[0060]

[Table 1]

From the table, it can be seen that the number of recesses with a specific major axis is 20 /
It was found that in both Comparative Examples 1 and 2 having a size of less than 4 mm ² , the interleaf paper property was insufficient and the adhered paper was easily peeled off. On the other hand, it was confirmed that Examples 1 and 2 have better interleaf paper properties than Comparative Examples 1 and 2, and the adhered paper is less likely to peel off. Further, when comparing the two examples, it was found that the example 1 having a larger number of concave portions having a specific major axis can improve the slip sheet property than the example 2.

[0062]

As described above in detail, according to the present invention,
It is possible to provide a novel polystyrene-based resin foam that has good interleaving property of paper due to conventionally commonly used water-based glue, etc., and is difficult to peel off the adhered paper, and a method for producing the same, which is an excellent effect. .

[Brief description of drawings]

FIG. 1 is an electron micrograph showing a surface layer surface state of a polystyrene-based resin foam produced in Example 1 of the present invention.

FIG. 2 is an electron micrograph showing a surface layer surface state of a polystyrene resin foam produced in Example 2 of the present invention.

FIG. 3 is an electron micrograph showing the state of the surface of the skin layer of the polystyrene resin foam produced in Comparative Example 1.

FIG. 4 is an electron micrograph showing the state of the surface of the skin layer of the polystyrene resin foam produced in Comparative Example 2.

FIG. 5 is a diagram illustrating a resin inflow angle θ of a capillary used for measuring a melt tension of a polystyrene resin.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 25:00 B29K 25:00 105: 04 105: 04 C08L 25:04 C08L 25:04 F term ( Reference) 4F074 AA32 CA22 CE02 DA02 DA03 DA13 DA52 4F207 AA13 AB02 AG03 AG20 AG26 KA01 KA11 KA19 KF04 KW26

Claims (7)

[Claims] 1. A plate-shaped or sheet-shaped polystyrene-based resin foam having a skin layer, wherein a recess having a major axis of opening of 25 μm or more and less than 100 μm per unit area is formed on the surface of the skin layer. A polystyrene resin foam having a ratio of 20/4 mm ² or more. 2. The polystyrene resin foam according to claim 1, wherein the surface roughness of the surface of the skin layer is 2 to 10 μm in terms of center line average roughness Ra. 3. The polystyrene resin foam according to claim 1, wherein the average cell diameter inside the foam is 0.4 mm or less. 4. The polystyrene resin foam according to claim 1, wherein the open cell ratio inside the foam is 15% or less. 5. The overall density is 0.05 to 0.12 g / cm.
The polystyrene resin foam according to claim 1, which is ³ . 6. A method for producing a polystyrene resin foam according to claim 1, wherein the polystyrene resin having a melt tension at 200 ° C. of 39.2 to 107.8 mN is extruded and foamed into a cylindrical shape. A method for producing a polystyrene-based resin foam, comprising: a step of cooling the outer surface of the cylinder immediately after extrusion; and a step of crushing the cooled cylinder and superposing the two layers to fuse them. 7. The outer surface 1 is provided on the outer surface of a cylinder immediately after extrusion.
^{30 to 4 at} a rate of 0.005 to 0.07 m ³ per m ^2.
The method for producing a polystyrene-based resin foam according to claim 6, wherein air of 0 ° C. is blown to cool.