JP2000309645A - Biaxially stretched styrene resin sheet - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the blocking property of a sheet, the releasability or transparency of a secondary molded article, and the scratch resistance. SOLUTION: A biaxially stretched resin sheet is manufactured from a resin component obtained by dispersing spherical silica having an average particle diameter of 1 to 20 μm in a styrene resin represented by SMAA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretched styrene resin sheet, and more particularly, to a sheet having good blocking resistance at the time of winding of the sheet and occurrence of abrasion at the time of transporting the sheet to a winding roll. The present invention relates to a biaxially stretched styrene-based resin sheet that suppresses bleeding and improves the releasability when a secondary molded product of the sheet is stacked.

[0002]

2. Description of the Related Art Biaxially stretched styrene-based resin sheets are widely used for packaging lightweight food packaging containers and other articles because of their excellent environmental hygiene, stiffness, transparency, moldability, and recoverability. Used. However, this biaxially stretched sheet has a drawback that it has a strong blocking property at the time of winding up the sheet, and it is difficult for a secondary molded product of the sheet to be peeled off at the time of use when stored in a stacked state. Further, when the sheet is hot-pressed, the anti-fog agent or silicone oil applied to the sheet is easily attached to the heating plate and the mold,
The appearance of the secondary molded product may be impaired.

[0003] Various studies have been made in the past to improve the blocking property at the time of winding the sheet and the releasability of the secondary molded product of the sheet. For example, amorphous silicon oxide fine particles are formed on a styrene resin. There is known a method of adding a powder, biaxially stretching a sheet, and projecting the fine powder on the sheet surface.

[0004]

However, when a sheet obtained by biaxial stretching is produced from a resin component obtained by blending such an amorphous silicon oxide fine powder with a styrene resin, Although it can prevent silicone oil from adhering to molds and the like to some extent, its effect is not sufficient, and it is difficult to uniformly disperse it in resin because silicon oxide fine powders are likely to agglomerate. In addition to poor appearance due to projections of agglomerates called eyes, fine scratches are likely to occur due to friction between the sheets when transporting the sheet in a rolled state.

[0005] The problem to be solved by the present invention is to improve the blocking property of a sheet and the releasability of a secondary molded product, and also to improve the appearance defects caused by agglomerate projections and silicone oil applicability, and Another object of the present invention is to prevent fine scratches caused by rubbing between sheets, that is, to improve scratch resistance.

[0006]

Means for Solving the Problems The present invention and the like have made intensive studies to solve the above-mentioned problems. As a result, a biaxially stretched styrene-based resin sheet is blended with a spherical inorganic granular material having a specific particle size to obtain a silicone oil. The coating property of the sheet is improved, the blocking property between the biaxially stretched sheets is weakened, the occurrence of abrasion when transporting the winding roll of the sheet is suppressed, and the releasability at the time of stacking the secondary molded product of the sheet is reduced. Have been found, and the occurrence of dirt due to the transfer of the coating agent to the heating plate and the mold of the hot-plate press forming machine has been reduced, and the present invention has been completed.

The styrene resin (A) used in the present invention is not particularly limited, and various conventionally known styrene resins can be applied. For example, styrene, homopolymers of aromatic vinyl monomers such as α-methylstyrene,
Alternatively, a binary or higher copolymer with another polymerizable monomer copolymerizable therewith may be used. Here, in the case where a binary or more copolymer of an aromatic vinyl monomer and another polymerizable monomer is used as the styrene resin (A),
The other polymerizable monomer is copolymerized using 50% by weight or less of the total weight of both monomers. Here, as other copolymerizable monomers, acid group-containing vinyl monomers represented by (meth) acrylic acid,
Examples include ester group-containing vinyl monomers represented by alkyl (meth) acrylate, and acid anhydride group-containing vinyl monomers represented by maleic anhydride and itaconic anhydride.

Among these, particularly, as the styrene resin (A), a binary copolymer of an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer is used. When a polymer is used, the heat resistance and the oil resistance of the biaxially stretched sheet and the molded article thereof are improved, and the effect of the present invention is extremely remarkable. That is, a binary copolymer of such an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer is a biaxially stretched sheet and a molded article thereof. Although it has excellent heat resistance and oil resistance, when used without the addition of inorganic particles, it has the drawback that the blocking between the sheets and the releasability of the secondary molded product are extremely low, In the present invention, when such a binary copolymer, which is inherently inferior in sheet blocking and releasability of a secondary molded product, is used, an excellent improvement effect is exhibited. When a copolymer is used, the heat resistance and oil resistance of the biaxially stretched sheet and the molded article thereof, as well as the sheet blocking properties, the releasability of the secondary molded article, the improvement of the appearance defect, the scratch resistance, etc. Performance can be combined.

Among the binary copolymers of this aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer, particularly, an improvement in the binary copolymer is mentioned. The styrene-methacrylic acid copolymer is preferred because the effect becomes more remarkable and the heat resistance and oil resistance are extremely good.

[0010] Further, in a binary copolymer of an aromatic vinyl monomer and an acid group-containing vinyl monomer or an acid anhydride group-containing vinyl monomer, an aromatic vinyl monomer is used. The content ratio of the acid group-containing vinyl monomer or the acid anhydride group-containing vinyl monomer is not particularly limited. 5 weight of vinyl monomer or acid anhydride group-containing vinyl monomer
The proportion may be 0% by weight or less, but from the viewpoint of extrudability and recoverability, a range of 1 to 20% by weight is more preferable.

The weight average molecular weight of the styrene resin (A) is not particularly limited, but is preferably 200,000 to 450,000 from the viewpoint of extrusion processability. The method for producing the styrene resin is not particularly limited, and a usual polymerization method can be employed.

Next, the spherical inorganic granular material (B) used in the present invention has an average particle diameter of 1 to 20 μm. That is, when the thickness is less than 1 μm, appropriate projections cannot be formed on the sheet surface, and the effect of the present invention is not exhibited. On the other hand, when the thickness is more than 20 μm, transparency is reduced and appearance defects are caused. Easy to wake up. The range of 2 to 10 μm is more preferable from the viewpoint that the performance balance is excellent and the high transparency of the secondary molded product is also good. Here, the average particle diameter was measured by a laser diffraction method.
0% volume average particle diameter.

Next, the particle size distribution of the spherical inorganic granular material (B) is preferably 2.5 or less from the viewpoint of improving the uniformity of the projections on the sheet surface. here,
The particle size distribution is measured by the laser diffraction method.
A ratio of 0% volume average particle diameter to 10% volume average particle diameter,
That is, it is a value represented by (90% volume average particle diameter) / (10% volume average particle diameter).

The spherical inorganic particles (B) are spherical particles as described above. That is, when the shape of the inorganic granular material is irregular, in order to impart sufficient roughness to the sheet surface, it is necessary to increase the amount of the inorganic granular material to be added, thereby impairing the transparency of the sheet, The scratch resistance of the sheet is reduced, and abrasion is likely to occur when the sheet is transported on a take-up roll. Such spherical particles have an aspect ratio calculated from the ratio of the major axis to the minor axis of 1-1.
It is preferably 5.

Further, in order to form uniform projections on the sheet surface and further improve the appearance, those having a shape closer to a true sphere are preferable, and specifically, the aspect ratio is more preferably 1 to 1.2. .

Further, the spherical inorganic particles (B) are preferably porous particles having a specific surface area of 400 m 2 / g or more, because they have good affinity with the styrene resin (A) and have uniform projections on the sheet surface. Is preferable since whitening hardly occurs at the corners of the molded product during deep drawing.

The spherical inorganic particles (B) are inorganic particles as described above. That is, when the granular material is an organic substance, the granular material is deformed during biaxial stretching, and during secondary molding,
It is easy to be buried, and the effect of the present invention is not exhibited.
Here, examples of the inorganic granular material include, but are not particularly limited to, spherical silica, glass beads, and the like, and those obtained by subjecting their surfaces to a chemical treatment, but are chemically stable. Spherical silica containing silicon oxide as a main component is preferred because the resin is not denatured by a catalytic action and the silicone oil is easily applied to the sheet.

The biaxially stretched styrene-based sheet of the present invention containing the styrene-based resin (A) and the spherical inorganic granular material (B) described above in detail as essential constituents comprises a styrene-based resin (A) containing It is preferable to add the system granular material (B) at a ratio of 50 to 1000 ppm. That is, when the addition amount of the spherical inorganic granular material (B) is 50 ppm or more, the number of projections on the surface of the biaxially stretched sheet becomes a sufficient level, and the releasability of the secondary molded product is further improved. When the content is 1000 ppm or less, the transparency of the sheet and the secondary molded product thereof becomes good. 5 from the point that these performance balance is excellent
0 to 500 ppm is more preferable, and 50 is more preferable.
３００300 ppm.

The biaxially-rolled styrene resin sheet of the present invention comprises:
As described above, it is composed of a resin component containing the styrene-based resin (A) and the spherical inorganic granular material (B) as essential components. Specifically, it is a single layer obtained from the resin component. Alternatively, a resin layer composed of the resin component (hereinafter, abbreviated as “S layer”) may be provided on both surface layers, and a central layer (hereinafter, referred to as “C layer”) sandwiched between the S layers. layer"
Abbreviated. ) May be a three-layer or five-layer multilayer sheet. That is, by arranging the S layer on the surface layer and exposing it on both surfaces of the biaxially stretched sheet, the effects of the present invention can be exhibited.

At this time, the center layer (C layer) sandwiched between the resin layers (S layers) containing the styrene resin (A) and the spherical inorganic particles (B) as essential components is not particularly limited. Although it is not, it is preferable that the styrene-based resin (A) is used because it has good affinity for the surface layer resin, but the S layer and the C layer do not need to be the same resin. The five-layer sheet includes S layer / C layer / S layer / C layer /
One having a layered structure of the S layer is exemplified.

In the above-mentioned three-layer or five-layer multilayer sheet, the fine particles dispersed in the surface resin are easily buried in the inner layer when biaxially stretched in the conventional multilayer sheet using irregular fine particles. Compared with a single-layer sheet, it is difficult to form projections on the sheet surface, so it was necessary to increase the content of the fine particles. In addition, scratch resistance can be exhibited.

The method for producing the multilayer sheet is not particularly limited, and the composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components is subjected to hot melt extrusion. Examples include a method of biaxial stretching, and a method of hot-melt coextrusion and biaxial stretching of the composition and other resin components.

Here, the method for preparing the composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components is not particularly limited. Examples thereof include a method of mixing the spherical inorganic granular material (B) with a stirrer such as a Henschel mixer or a tumbler, and a method of melt-kneading the mixture with an extruder, a kneader or the like.

To the styrene resin (A), mineral oil, a slip agent, an antistatic agent, an antioxidant, an antibacterial agent, an ultraviolet absorber, etc., which are added as an internal lubricant, can be added as required. Further, the composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components includes impact polystyrene (HIPS), styrene-butadiene-styrene block copolymer (SBS), styrene- Butadiene- (meth) acrylate copolymer (MBS)
And other styrene-modified rubbers can be mixed as long as the transparency of the sheet is not impaired. By adding the styrene-modified rubber to the styrene-based resin (A), the corners of the molded product are easily whitened during deep drawing of the sheet. Therefore, the amount of addition is preferably 5% or less.

When the styrene resin (A) is used as the main component as the resin component forming the central layer (C layer), the above-mentioned various additives and styrene-modified rubbers can be used in combination.

In order to produce the biaxially stretched sheet of the present invention from the resin components adjusted as described above, a composition containing the styrene resin (A) and the spherical inorganic particles (B) as essential components. After extruding the material from the die after melt-kneading, or stretched to obtain the target biaxially stretched styrene resin sheet,
Alternatively, a composition comprising a styrene-based resin (A) and a spherical inorganic granular material (B) as essential components and a resin component for forming a central layer (C layer) at 200 to 300 ° C. in an extruder. The resulting mixture is melt-kneaded, extruded from a die, and stretched to obtain a target biaxially stretched styrene resin sheet. In the case of forming a multilayer sheet, as described above, the sheet is subjected to a stretching treatment after coextrusion.

The stretching method is not particularly limited, but the unstretched sheet extruded from the die is
A method of performing simultaneous biaxial stretching or sequential biaxial stretching using a speed difference between rolls and a tenter is preferable. Although the stretching ratio varies depending on the purpose, it is usually 3 to 15 times, more preferably 4 to 10 times in area ratio. In the case of sequential stretching, the stretching ratio in the flow direction is 1.2 to 5 times, and especially 1.5 to 4 times.
Is preferable, and the stretching ratio in the cross direction is 1.2 to 5 times.
Among them, 1.5 to 3 times is preferable. The stretching ratio in each direction of simultaneous biaxial stretching is 1.5 to 5 times, preferably 2 to 4 times.

The temperature conditions in simultaneous biaxial stretching or sequential biaxial stretching are not particularly limited.
It is preferable that the orientation relaxation stress measured in accordance with STM D-1504 be 0.15 to 1.3 MPa, from the viewpoint that stretching can be prevented from breaking and the secondary formability can be improved.

The surface of the biaxially stretched sheet can be appropriately coated with an antifogging agent, an antistatic agent and a silicone oil. In the present invention, the effects of the present invention are particularly remarkable. That is, it is preferable to apply a silicone oil from the viewpoint that various effects such as the sheet blocking property, the releasability of the secondary molded product, and the scratch resistance are remarkable. In particular, in the present invention, even when silicone oil is applied to the sheet surface, adhesion of the silicone oil to the heating plate and the mold can be prevented, and the appearance of the secondary molded product becomes excellent.

The amount of the silicone oil to be applied is not particularly limited, but it is preferable to apply the silicone oil in at least 5 to 50 mg / m 2 on at least one side in order to exhibit the above-mentioned sheet performance. Also, as the silicone oil, polydimethylsiloxane is preferable because it does not easily attack the sheet surface during high-temperature molding.

[0031]

EXAMPLES The present invention will be described in detail with reference to Examples and Comparative Examples, but the content of the present invention is not limited to these Examples. In addition, each evaluation item was implemented in the following way.

[Transparency of Sheet] The haze value of the sheet was measured according to JIS K7105.

Criteria ◎: less than 1%, ○: less than 1-2%, Δ: less than 2-3%,
×: 3% or more

[Sheet Surface Condition (Surface Roughness and Protrusion Uniformity)] The surface of the sheet was observed using an epi-polarizing microscope (100 times). The number of projections was evaluated. Criteria 基準: 20 or more, Δ; 10 to less than 20,
×: Less than 10 Regarding the protrusion uniformity, the surface of the sheet was observed using an epi-polarizing microscope. The micrographs of Example 1, Comparative Example 1 and Comparative Example 4 are shown in FIGS.

[Coatability of Silicone Oil] The above sample was immersed in a silicone emulsion liquid (containing 1% silicone oil and a nonionic surfactant) at 25 ° C., and a rubber having a speed of 5 m / min and a pressure of 0.4 MPa was used. After being squeezed with a nip roll made, it was dried with a dryer. These samples were measured for the average silicon coating amount on one side of the sample by a fluorescent X-ray analyzer.

Criteria ○: 15 mg / m 2 or more, Δ;
10 to less than 15 mg / m2, x; less than 10 mg / m2

[Scratch Resistance of Sheet] The coated surfaces of the samples coated with 10 to 20 mg / m 2 of silicone oil were overlapped and rubbed 20 times with a load applied to the sheet so as to obtain a pressure of 389 Pa. , JIS
The haze value of the sheet was measured with K7105. Criteria ◎: less than 4%, ；: less than 4 to 8%, Δ: less than 8 to 12%, ×: 12% or more

[Releasability of Secondary Molded Article] Twenty molded articles of the partition tray for confectionery were stacked, and the height when a load of 3.5 kgf was applied from the top for 1 minute was T1, and then the load was removed. The peelability of the secondary molded product was evaluated using the height after one minute as T2 and the recovery rate (%) of the height of the molded product shown in the formula 1 as an index.

Formula 1: Recovery rate (%) = (T2−T1) / T1 Criteria ；: 120% or more, ；: 80 to less than 120%, Δ; 40
Less than 80%, ×; less than 40%

Example 1 Transparent polystyrene (GPPS) (manufactured by Dainippon Ink and Chemicals, Inc., trade name: Dick Styrene CR5600)
200 ppm of spherical silica having an average particle size of 4.5 μm, a particle size distribution width of 1.9, a specific surface area of 520 m 2 / g, and an aspect ratio of 1 to 1.1 (manufactured by Fuji Silysia Chemical Ltd., trade name: Silosphere C-1504). The resin composition melt-mixed at a certain ratio is extruded from a T-die to a thickness of 1.0
Was prepared. Next, using a biaxial stretching apparatus, the sheet was placed in a 120 ° C. atmosphere in both longitudinal and transverse directions.
The film was stretched twice to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Subsequently, 10 to 20 mg / m2 of silicone oil was applied to both sides of the sheet.

Example 2 Resin (3% SMAA) in which methacrylic acid was copolymerized at a ratio of 3% by weight with respect to a styrene monomer (Mw = 260,000;
Mw / Mn = 2.5) and a resin composition obtained by melting and mixing spherical silica having an average particle diameter of 4.5 μm (manufactured by Fuji Silysia Chemical Ltd., trade name: Silosphere C-1504) at a ratio of 200 ppm. A sheet of 0.0 mm was produced. Next, using a biaxial stretching device, the sheet is
The film was stretched 2.2 times in both the vertical and horizontal directions in an atmosphere at 25 ° C. to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Then, 10 to 2 on each side of the sheet
0 mg / m2 of silicone oil was applied.

Example 3 Resin (10% SMAA) in which methacrylic acid was copolymerized in a ratio of 10% by weight to styrene monomer (Mw = 30)
Mw / Mn = 2.5) and a resin composition obtained by melting and mixing spherical silica having an average particle size of 4.5 μm (manufactured by Fuji Silysia Chemical Ltd., trade name: Silosphere C-1504) at a ratio of 200 ppm. A sheet having a thickness of 1.0 mm was produced. Next, using a biaxial stretching apparatus, the sheet was stretched 2.2 times in both the longitudinal and transverse directions in a 140 ° C. atmosphere to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Then, 10 sheets on each side of the sheet
〜20 mg / m 2 of silicone oil was applied.

Example 4 An average particle diameter of 10.0 μm was obtained in the same manner as in Example 3.
m, a particle size distribution of 2.3, a specific surface area of 520 m2 / g, and an aspect ratio of 1 to 1.1 spherical silica (manufactured by Fuji Silysia Chemical Ltd., trade name: Silosphere C-1510).
It was dispersed at a rate of 00 ppm to obtain a biaxially stretched styrene resin sheet having a thickness of 0.21 mm. Subsequently, 10 to 20 mg / m2 of silicone oil was applied to both sides of the sheet.

Example 5 Resin (3% SMAA) obtained by copolymerizing methacrylic acid at a ratio of 3% by weight to styrene monomer (Mw = 260,000;
Mw / Mn = 2.5) and a resin composition obtained by melt-mixing spherical silica having an average particle diameter of 4.5 μm (manufactured by Fuji Silysia Chemical Ltd., trade name: Silosphere C-1504) at a ratio of 200 ppm as both surface layers. , A transparent polystyrene resin (Dainippon Ink Chemical Industry Co., Ltd., Dick Styrene CR5600) was co-extruded as an inner layer sandwiched between the surface layers, passed through a two-type, three-layer distributor, and extruded from a T-die. 1.0mm thickness with a ratio of 2/96/2
Made a multi-layer sheet. Next, using a biaxial stretching device, the sheet was stretched 2.2 times in both the longitudinal and transverse directions in an atmosphere of 120 ° C. to obtain a biaxially stretched styrene resin laminated sheet having a thickness of 0.21 mm. . Next, 10 to 20 mg / m2 of silicone oil was applied to both sides of the sheet.

With respect to the biaxially stretched styrene-based sheets coated with the silicone oils of Examples 1 to 5, the transparency of the sheet, the surface roughness of the sheet, the applicability of the sheet to silicon, the scratch resistance of the sheet, and the Table 1 shows the results of evaluating the releasability. In each example, excellent results were obtained in each evaluation test.

COMPARATIVE EXAMPLE 1 Amorphous silica having an average particle size of 6.8 μm (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name: Carplex # 80) was dispersed by the same production method as in Example 1, and the thickness was coated with silicone oil. A 0.21 mm GPPS biaxially stretched sheet was obtained. Next, various tests were performed in the same manner as in Examples 1 to 5.
Table 2 shows the results. FIG. 2 shows the result of observing the sheet surface with a microscope. It can be seen that projections are present on the sheet surface, but the size is non-uniform. Although there was no problem with the releasability of the secondary molded product, the scratch resistance of the sheet was extremely poor.

Comparative Example 2 Amorphous silica having an average particle diameter of 1.8 μm and having been subjected to a hydrophobic treatment on its surface (manufactured by Fuji Silysia Chemical Ltd., trade name: Silo Hobic, by the same production method as in Example 2) 200) was dispersed, and a silicone oil-coated 0.21 mm thick, 3% SMAA biaxially stretched sheet was obtained. Next, various tests were performed in the same manner as in Examples 1 to 5. Table 2 shows the results. Table 2 shows the results. The surface roughness of the sheet is not sufficient, and the releasability of the secondary molded product is extremely poor.

Comparative Example 3 According to the same production method as in Example 3, 10% of no granular material was added.
A biaxially stretched sheet coated with silicone oil was obtained using SMAA resin (granular material (B) was not used). Next, various tests were performed in the same manner as in Examples 1 to 5. Table 2 shows the results. Since no granular material was added, no protrusions were present on the sheet surface, and the releasability of the secondary molded product was extremely poor.

Comparative Example 4 Amorphous silica having an average particle size of 2.0 μm (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name: Carplex CS-7) was dispersed in the same manner as in Example 3, and silicone oil was applied. % SMAA biaxially stretched sheet was obtained. Next, various tests were performed in the same manner as in Examples 1 to 5. Table 2 shows the results. FIG. 3 shows a micrograph of the obtained sheet. Despite the addition of the granular material, microscopic observation shows that there are almost no projections on the sheet surface, and not only the releasability of the secondary molded product is poor, but also the scratch resistance of the sheet is extremely poor.

Comparative Example 5 Transparent polystyrene resin (GPPS) (manufactured by Dainippon Ink and Chemicals, Inc., trade name: Dick Styrene CR560)
0), amorphous silica having an average particle size of 2.0 μm (manufactured by Shionogi Pharmaceutical Co., Ltd., trade name: Silosphere C-150)
A resin composition obtained by melting and mixing 4) at a ratio of 200 ppm was used as both surface layers, and the polystyrene resin (CR5600) containing no fine particles was co-extruded as an inner layer sandwiched between the surface layers, and passed through a two-type three-layer distributor. After extruding from the T die, the thickness of the layer is 1.0 mm at a layer composition ratio of 6/88/6.
Made a multi-layer sheet. Next, the sheet was stretched 2.2 times in the longitudinal and transverse directions in a 120 ° C. atmosphere to obtain a biaxially stretched styrene resin laminated sheet having a thickness of 0.21 mm. Furthermore, 10-20 m on each side of the sample
g / m2 of silicone oil was applied. Next, various tests were performed in the same manner as in Examples 1 to 5. Table 2 shows the results. Although the transparency of the sheet is good, the performance such as the releasability of the secondary molded product is insufficient.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

According to the present invention, the blocking property of the sheet and the releasability of the secondary molded article are improved, and the poor appearance due to the aggregation of the projections of the aggregates and the applicability of the silicone oil are improved. In addition, it is possible to prevent fine scratches caused by rubbing between sheets, that is, to improve scratch resistance. Therefore, it is possible to improve the workability at the time of the secondary forming of the sheet, and it is possible to suppress the occurrence of abrasion at the time of transport of the winding roll of the sheet,
It can also be expected that the defective rate of secondary molded products will decrease.

[Brief description of the drawings]

FIG. 1 is a photograph of the sheet obtained in Example 1 photographed by an epi-polarizing microscope.

FIG. 2 is a photograph of the sheet obtained in Comparative Example 1 photographed by an epi-polarizing microscope.

FIG. 3 is a photograph of the sheet obtained in Comparative Example 4 taken with an epi-polarizing microscope.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B29L 7:00 C08L 25:04 (72) Inventor Nobuyuki Konishi 3-1-25 F-term, Chuo-ku, Chuo-ku, Chiba-shi, Chiba reference) 4F071 AA22 AA22X AA32X AA76X AB26 AD02 AE17 AF19 AF30 AF53 BA01 BB06 BB08 BC01 BC03 BC08 4F100 AA01A AA01C AA20A AA20C AK12A AK12C AK12J AK24A AK24C AK24J AL01A AL01C AT00B BA02 BA03 BA06 BA10A BA10C CA23 DE01A DE01C EJ38 JB04 JK06 JK20 JL00 YY00A YY00C 4F210 AA13E AB16 AB17 AC04 AE01 AG01 AG03 QC05 QG01 QG15 QG18

Claims (8)

[Claims] 1. A biaxially stretched resin sheet containing a styrene resin (A) as a main component, in which a spherical inorganic particle (B) having an average particle diameter of 1 to 20 μm is dispersed. A biaxially stretched styrene resin sheet characterized by the above-mentioned. 2. A biaxially stretched resin sheet comprising a styrene resin (A) and spherical inorganic particles (B) in an amount of 50 to 1000 p.
The sheet according to claim 1, wherein the sheet is dispersed at a ratio of pm. 3. The sheet according to claim 1, wherein the spherical inorganic particles (B) have an aspect ratio of 1 to 1.5. 4. The sheet according to claim 1, wherein the spherical inorganic granular material (B) has a particle size distribution width of 2.5 or less. 5. The sheet according to claim 1, wherein the spherical inorganic particles (B) are spherical silica. 6. A resin layer comprising, as a main component, a styrene resin (A) in which spherical inorganic particles (B) having an average particle diameter of 1 to 20 μm are dispersed, at least on both surface layers. The sheet according to any one of 1 to 5. 7. The sheet according to claim 1, wherein the styrene resin (A) is a copolymer of a styrene monomer and an ethylenically unsaturated carboxylic acid monomer. 8. A biaxially stretched styrene resin sheet, wherein the amount of the ethylenically unsaturated carboxylic acid monomer in the copolymer according to claim 7 is 1 to 50% by weight.