JP2010201623A - Laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated sheet which is excellent in oil resistance, solvent resistance, abrasion resistance, etc., and has high mechanical strength (impact strength, tear strength, etc.) although it is thin. <P>SOLUTION: The laminated sheet has a two- or three-layer structure and is formed by laminating a thermoplastic resin film, which is more resistant to oil than a polystyrene resin, on a polystyrene resin sheet, which is stretched to an expansion ratio of 1.1-4.0 and a drawing ratio of 3.0 or below in at least one direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laminated sheet obtained by laminating a specific film on a foamed and stretched polystyrene resin sheet.

  Conventionally, polystyrene-based resin sheets (particularly, expanded polystyrene sheets (hereinafter sometimes referred to as “PSP”)) are widely used as manufacturing materials for various food containers such as sugar beet containers because of their excellent thermoformability. ing. However, since PSP is not sufficient in oil resistance, solvent resistance, abrasion resistance and the like, its use is limited, and there is a problem in using it especially as a buffer sheet for transporting and conveying plate-like members. Further, if it is attempted to cover the decrease in the mechanical strength of the sheet, there is a problem that the wall becomes thick and the storage space and the transportation cost increase.

  Patent Document 1 discloses a foamed polystyrene sheet having a thickness of 0.1 to 1.0 mm which is foamed at a foaming ratio of 1.07 to 2.1 and stretched biaxially in a range of 1.5 to 5.0 times. It is disclosed. However, oil resistance, solvent resistance, abrasion resistance, and the like have not been sufficient for use as a buffer sheet for transporting and conveying plate-like members, not for food storage.

  Furthermore, Patent Document 2 contains a polymer antistatic agent in a base material layer made of a styrene resin and an olefin resin having an expansion ratio of 1.47 to 2.43 and a thickness of 0.8 to 1.47 mm. A sheet in which an olefin resin is laminated on at least one surface is disclosed. However, although it has excellent wear resistance, it has become a thick sheet in order to maintain mechanical strength.

  In recent years, oil resistance, solvent resistance, abrasion resistance, mechanical strength, etc. have been strongly demanded for applications such as buffer sheets for transporting and conveying plate-like members. In addition, a polystyrene-based resin sheet that is excellent in solvent resistance, abrasion resistance, and the like and that has been reduced in thickness while maintaining mechanical strength has not been completed, and development of such a sheet has been desired.

JP-A-57-126628 JP 2004-90609 A

  The present invention has been made in view of the above-mentioned background art, and the object of the present invention is excellent in oil resistance, solvent resistance, abrasion resistance, etc., and mechanical strength (impact strength) although the sheet is thin. Another object is to provide a laminated sheet having excellent tear strength and the like.

  As a result of intensive studies to solve the above problems, the inventor has a thin thickness if a specific resin sheet that is foamed and stretched is used, even if a thermoplastic resin film having oil resistance is laminated. Nevertheless, the present inventors have found that a laminated sheet excellent in mechanical strength (impact strength, tear strength, etc.) can be obtained, and reached the present invention.

  That is, in the present invention, the polystyrene resin sheet stretched so that the expansion ratio is 1.1 to 4.0 times and is 3.0 times or less in at least one has more oil resistance than the polystyrene resin. The present invention provides a laminated sheet characterized in that the layer structure is formed by laminating a thermoplastic resin film and has a two-layer structure or a three-layer structure.

  According to the present invention, the above-mentioned problems are solved and the above-mentioned problems are solved, and the oil resistance, solvent resistance, wear resistance, etc. are excellent, and the mechanical strength (impact strength, tearing, etc., despite the thin sheet thickness). A laminated sheet having excellent strength and the like can be provided.

  Hereinafter, the present invention will be described. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented.

<Polystyrene resin sheet>
<< Resin composition >>
The laminated sheet of the present invention is formed by laminating a thermoplastic resin film that is more oil resistant than a polystyrene resin on a polystyrene resin sheet. The sheet material of the polystyrene-based resin sheet is not particularly limited as long as it is a polystyrene-based resin. For example, when a polystyrene-based resin not containing a rubber component is (A) and a polystyrene-based resin containing a rubber component is (B) , (A) alone, (B) alone or a mixture of (A) and (B).

  Typical examples of (A) include polystyrene such as general-purpose polystyrene (hereinafter sometimes referred to as “GPPS”), and further styrene and alkylstyrene (for example, o-, m-, p-). Homopolymers of aromatic vinyl compounds such as methyl styrene, p-ethyl styrene, pt-butyl styrene), α-alkyl styrene (eg, α-methyl styrene, α-ethyl styrene), and combinations of these monomers And styrene- (meth) acrylic acid ester copolymers (for example, styrene-butyl acrylate copolymers), styrene- (meth) acrylic acid copolymers, and the like. These can be used alone or in combination of two or more.

  (A) can be used alone or in combination with (B). When (A) is used alone, (A) can be used as one type as (A) or in combination of two or more types as (A). Even when (A) is used in combination with (B), (A) is a range having compatibility with (B), and (A) is one type, or (A) is a combination of two or more types. Can be used. (A) is preferably GPPS. (A) other than the above-described GPPS is preferably used alone or in combination of two or more in a range having compatibility with GPPS.

  Among GPPS, GPPS having a melt flow rate of 0.5 to 20 g / 10 minutes at a temperature of 200 ° C. and a load of 5 kg is preferable, and GPPS having a range of 2 to 10 g / 10 minutes is particularly preferable. By using such GPPS, melt kneading and extrusion foaming at a relatively low temperature are possible, and dispersibility of the kneading type antistatic agent described later is improved.

  Examples of (B) include HIPS, which is representative of graft copolymers, and styrene-butadiene-styrene block copolymers (hereinafter, “SBS”), which are representative of ABA type block copolymers. And styrene-isoprene-styrene block copolymer (hereinafter sometimes referred to as “SIS”). “HIPS” includes a blend type HIPS obtained by blending this graft type HIPS and GPPS in addition to a graft type HIPS alone in which at least a styrene monomer is graft-polymerized to a rubber component (however, blended GPPS). Are classified as (A)).

  The polystyrene resin having the rubber component (B) may be a hydrogenated product as long as it has compatibility.

  Examples of the rubber used in the production of (B) include non-styrene rubbers such as butadiene rubber, isoprene rubber, acrylic rubber, and butadiene-isoprene rubber; and styrene rubbers such as styrene-butadiene rubber and styrene-isoprene rubber. Can be mentioned. Among them, butadiene rubber is preferable, and among butadiene rubbers, a high cis type having a high content of cis-1,4 structure is preferable from the viewpoint of thermal stability than a low cis type having a low content.

  The “rubber component” in the present invention refers to a component having a low elastic modulus that is bonded to a polystyrene-based resin, for example, the rubber described above.

  The rubber component content is calculated by measuring the diene content by potentiometric titration using iodine monochloride, potassium iodide and sodium thiosulfate standard solution, and calculating the diene content as the rubber component content. Analytical methods include, for example, the Japan Analytical Chemical Society, Polymer Analysis Research Roundtable, “New Edition Polymer Analysis Handbook”, Kinokuniya (1995 version), P.A. 659 “(3) Rubber content”, measured by this method and defined as the value so measured.

  The content of the rubber component in (B) is preferably from 3 to 50 mass%, more preferably from 5 to 40 mass%, particularly preferably from 7 to 30 mass%, based on the entire (B).

  (B) is preferably a HIPS or SIS copolymer having a melt flow rate of 0.5 to 20 g / 10 min at a temperature of 200 ° C. and a load of 5 kg, and a HIPS of 2.0 to 10 g / 10 min. And SIS are particularly preferred. (B) can be used alone or in combination with (A). (B) When used alone, (B) can be used in one type as (B) or in combination of two or more types as (B). Even when (B) is used in combination with (A), (B) is a range having compatibility with (A), and (B) is one type or (B) is a combination of two or more types. Can be used.

  By using such a polystyrene resin, melt kneading and extrusion foaming at a relatively low temperature are possible, and dispersibility of the kneading type antistatic agent described later is improved.

  The content of a preferable rubber component with respect to the whole polystyrene resin sheet is 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less. If the rubber component is not contained, the impact strength and tear strength of the produced styrene resin sheet, laminated sheet and molded product (container etc.) are not improved and may be easily broken or easily broken. On the other hand, when the content of the rubber component is too large, not only the extrusion stability and the stretching stability during production deteriorate, but also the rigidity of the produced styrene resin sheet, laminated sheet and molded product thereof decreases. There is a case.

  The above (A) and / or (B) may have any resin composition as long as the rubber component content is in the above range and the stretching ratio of the laminated sheet is within the range described below. Absent. If blended so that the content of the rubber component in the polystyrene-based resin sheet falls within the above range, even if a small amount of (B) containing a large amount of rubber component is blended into the range, A large amount of (B) having a small content may be blended so as to fall within the range. Moreover, the rubber component does not need to be contained.

<< Foaming ratio >>
The expansion ratio of the polystyrene resin sheet in the laminated sheet of the present invention is essential to be in the range of 1.1 to 4.0 times. The expansion ratio (P) is the density (Q) of the foam sheet measured according to JIS K7222, and the density (R) of the foam material measured according to JIS K7112 D method (R). ), P = R / Q. The expansion ratio is preferably 1.15 to 3.5 times, particularly preferably 1.2 to 3.0 times. If the expansion ratio is too small, flexibility, buffering properties, sheet surface appearance, etc. may be inferior. On the other hand, if the expansion ratio is too large, the sheet surface appearance may be deteriorated, the mechanical strength (impact strength, tear strength, etc.) may be reduced, the mold reproducibility during thermoforming and the appearance of the molded product may be deteriorated.

  The expansion ratio can be controlled by the type of foaming agent, particularly the blending amount, the resin temperature during foaming extrusion, the resin pressure, and the like. The polystyrene-based resin sheet in the present invention can achieve the above expansion ratio while keeping other physical properties good. In particular, even if the expansion ratio becomes large (for example, 1.24 times or more), the mechanical strength can be kept good.

  In the present invention, a foaming agent is blended as an essential component during the production of the polystyrene-based resin sheet. As blowing agents, volatile blowing agents such as propane, butane, pentane and hexane; ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, sodium citrate, azo compounds (azobisisobutyronitrile, azodicarbonamide, diazoamino) Benzene, etc.), sulfonyl hydrazide compounds (benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, diphenyloxy-4,4′-bissulfonylhydrazide, etc.), nitroso compounds (N, N′-dinitrosopentamethylenetriamine, etc.), etc. Examples include foaming agents (decomposable foaming agents); gases such as carbon dioxide and nitrogen gas; water and the like, and these foaming agents may be used in combination.

  The foam molding method includes (1) a method of extruding by adding a chemical foaming agent, (2) a method of extruding while injecting a foam gas material, and (3) impregnating a resin with a liquid foam gas material. A method of extruding the product can be applied. Among them, the method of (1) is preferable from the viewpoint of handling property of the foaming agent, stability during stretching, and expansion ratio, and a polystyrene-based masterbatch (for example, Polyslen ES manufactured by Eiwa Chemical Industry Co., Ltd.) Series, Sankyo Kasei Co., Ltd. cell microphone MB6000 series) can be suitably used. In addition, for food use, polyolefin hygiene association registered products can be selectively used from the above.

  0.1-5 mass parts is preferable with respect to 100 mass parts of said polystyrene-type resins, the compounding quantity of a foaming agent has more preferable 0.3-3 mass parts, and its 0.5-2 mass parts is especially preferable. If the amount of the foaming agent is too small, not only the flexibility and buffering properties are not obtained, but also the sheet surface appearance may be inferior. On the other hand, if the amount is too large, not only the sheet surface appearance deteriorates, but also the mechanical strength. (Impact strength, tear strength) may be reduced, and mold reproducibility at the time of thermoforming and appearance of the molded product may be deteriorated.

  Since the expansion ratio can be adjusted as appropriate by adjusting the type, blending amount, resin temperature, resin pressure, and the like of the foaming agent, the expansion ratio is adjusted to 1.1 to 4.0 in the present invention.

  In addition, fillers (for example, talc, silica, kaolin, mica, calcium carbonate, magnesium carbonate, etc.) and bubble regulators (for example, acid salts such as polycarboxylic acid, A reaction mixture of a polyvalent carboxylic acid and sodium carbonate or sodium bicarbonate, etc.) may be used, or a masterbatch made in the same manner as the foaming agent may be used. The ratio of these fillers and bubble regulators is usually 0.01 to 2 parts by mass with respect to 100 parts by mass of the polystyrene resin.

<< stretch ratio >>
The polystyrene resin sheet in the present invention is stretched so that at least one of the stretching ratios is 3.0 times or less. Here, the “stretch ratio” is the ratio at which the length of the straight line written on the test piece of the polystyrene-based resin sheet changes before and after shrinkage. Specifically, the following formula, that is, the stretch ratio = Y / Z means a value (unit [times]) calculated by Z. In this formula, Y is a test piece of a polystyrene-based resin sheet, using a ruler and a writing instrument, in the longitudinal direction (sheet extrusion direction, hereinafter referred to as “MD”) and in the lateral direction (of the sheet). Indicates the length [mm] of a straight line drawn in the direction perpendicular to the extrusion direction (hereinafter sometimes referred to as “TD”), and Z is the shrinkage of the test piece immersed in a 140 ° C. silicone oil bath for 10 minutes. It shows the length [mm] of the straight line after being made.

  The polystyrene resin sheet in the present invention preferably has at least one draw ratio of 1.2 to 2.9 times, particularly preferably 1.5 to 2.8 times. If the draw ratio exceeds 3.0 times, the improvement in mechanical properties due to stretching is saturated, so there are cases where it does not make sense to stretch beyond this. On the other hand, if the draw ratio is too small, the mechanical strength (impact strength, tear strength) is not improved, and cracking or tearing may occur. Moreover, as for the polystyrene-type resin sheet in this invention, it is still more preferable that the draw ratio of both MD and TD is the said range.

  Further, in the polystyrene resin sheet in the present invention, it is essential that the product of the draw ratios in the longitudinal direction and the transverse direction is 9.0 or less, but preferably 1.4 to 8.5, particularly preferably. 2.2 to 7.9. Here, the product of the draw ratio in the machine direction and the transverse direction means a value obtained by multiplying the draw ratio in the machine direction and the draw ratio in the transverse direction (that is, the area ratio). If the product of the draw ratio is too small, the mechanical strength (impact strength, tear strength) decreases, so the sheet and the molded product obtained by thermoforming may be easily broken or easily broken. is there. On the other hand, if the product of the draw ratio is too large, the elongation of the sheet is reduced during thermoforming, the mold reproducibility is deteriorated, the appearance is deteriorated, the rigidity of the laminated sheet is too high, the flexibility, the buffering property, etc. In some cases, it is not preferable.

  The draw ratio of the polystyrene resin sheet can be controlled, for example, by adjusting the roll speed in the above-described longitudinal stretching and the tenter width in the transverse stretching. Specifically, increasing the ratio of the stretching end roll speed to the stretching start roll speed in the longitudinal stretching roll increases the longitudinal stretching ratio, and increasing the outlet width relative to the tenter inlet width increases the lateral stretching ratio. Conversely, when the roll speed ratio is lowered or the outlet width is narrowed, the draw ratio in the longitudinal / lateral direction becomes smaller.

<< Thickness of polystyrene resin sheet >>
The thickness of the polystyrene resin sheet is preferably 0.05 to 0.8 mm. If the thickness of the polystyrene resin sheet is too thin, the resulting laminated sheet itself and the molded product will have insufficient rigidity, and when used repeatedly as a laminated sheet, it may be cut, broken or easily wrinkled. . In particular, when the laminated sheet of the present invention is used as a buffer sheet for transportation / conveyance, the buffering action may be reduced in addition to the above obstacles. On the other hand, if the thickness of the polystyrene-based resin sheet is too thick, the laminated sheet or molded product obtained from it will increase in bulk and stack height, resulting in an increase in storage space and transportation cost, and a recycling and cost viewpoint. May be undesirable. From the viewpoint of reducing the thickness and weight, a more preferable range is 0.08 to 0.6 mm, and a particularly preferable range is 0.1 to 0.5 mm.

  In general, in order to keep the mechanical strength (impact strength, tear strength) good, a method of increasing the thickness of the polystyrene resin sheet is taken, but the polystyrene resin sheet in the present invention has an expansion ratio of 1. .1 to 4.0 times, and by drawing to a draw ratio of 3.0 times or less, particularly reducing the thickness and weight while maintaining good mechanical strength (impact strength, tear strength, etc.) Is possible. That is, even if the thickness and weight are reduced, it is possible to ensure the stability of stretching, and it is possible to ensure the strength because cracks and tears are unlikely to occur.

  In the laminated sheet of the present invention, since the thermoplastic resin film is laminated on one side or both sides of the polystyrene-based resin sheet, the thickness of the laminated sheet as a whole is increased. Therefore, the characteristic of the polystyrene-based resin sheet itself that “strength can be ensured even if it is thin and light” particularly matches the “laminated sheet in the direction of increasing thickness” of the present invention. The laminated sheet of the present invention can achieve both mechanical strength (impact strength, tear strength, etc.), oil resistance, solvent resistance, wear resistance, etc., with the desired sheet thickness.

  Furthermore, the laminated sheet of the present invention can be used particularly as a buffer sheet for transporting and transporting plate-like members (for example, glass, display panels using glass, building members provided with decoration, etc.). It is a laminated sheet, and in order to make use of the advantages such as improved transport efficiency by reducing the thickness and weight of the sheet, the compatibility of the above performances of the present invention is very effective, and it matches very well for such applications. Is.

  Further, the polystyrene resin sheet in the present invention has an average major axis of the bubble cell observed with an electron microscope from the direction perpendicular to the sheet surface, and an average aspect ratio (= average average diameter of bubbles / average of bubbles). The minor axis is preferably 1 to 4. When the expansion ratio is the above essential range or the preferred range, the average length of the bubble major axis is 200 to 2000 μm, and the average value of the aspect ratio is 1 to 4, good surface appearance, surface uniformity, pearl tone Gloss and feel. In addition, it is possible to obtain a product having good mold reproducibility at the time of thermoforming and having a good appearance with no shading or bubble marks.

  Regarding the size and shape of the bubble cell, the average major axis is more preferably 300 to 1500 μm, and particularly preferably 500 to 1000 μm. Further, the average aspect ratio is more preferably 1 to 3, and particularly preferably 1 to 2.

  Control of the size and shape of the bubble cell can be controlled by the type and blending amount of the foaming agent, particularly the resin temperature at the time of foaming extrusion, the resin pressure, particularly the MD, TD stretch ratio, and the like. Specifically, when the longitudinal draw ratio and / or the transverse draw ratio is increased, the average major axis is increased, and when the difference between the longitudinal draw ratio and the transverse stretch ratio is increased (anisotropy is increased), the average is increased accordingly. The aspect ratio is also increased.

<Thermoplastic resin film>
The laminated sheet of the present invention is characterized in that a thermoplastic resin film that is more oil resistant than a polystyrene resin is laminated on the above polystyrene resin sheet. A thermoplastic resin film will not be specifically limited if it has oil resistance rather than a polystyrene-type resin. Here, “having oil resistance than polystyrene-based resin” means that the degree of erosion by medium-chain fatty acid triglycerides is smaller than that of polystyrene-based resin sheet when the “oil resistance” described in the examples is evaluated. Preferably, when the “oil resistance” described in the examples is evaluated, there is no erosion by the medium-chain fatty acid triglyceride and it is determined as “good”. When the same oil resistance evaluation is performed on the polystyrene-based resin sheet, the surface is eroded by medium-chain fatty acid triglyceride and is determined to be “inferior”.

  It is preferable that the thermoplastic resin film in the present invention is more wear resistant than a polystyrene resin. Here, “having more abrasion resistance than polystyrene-based resin” means that the weight loss after the abrasion test is smaller than that of the polystyrene-based resin sheet in the evaluation of “wear resistance” described in Examples.

Examples of the thermoplastic resin film in the present invention include a polyolefin resin film, a polyester resin film, a polycarbonate resin film, a polyvinyl chloride resin film, a polyvinylidene chloride resin film, a polyvinyl acetate resin film, and a polyamide resin. Examples thereof include a resin film, a polyacetal resin film, a polyarylate resin film, a polyvinyl fluoride resin film, and a poly (meth) acrylate resin film. These may be used alone or in combination of two or more if they are compatible with each other.
The meaning of “A-based resin” includes not only a homopolymer of A but also a resin in which A is copolymerized, and the same applies hereinafter.

  Among these, oil resistance, solvent resistance, wear resistance, etc. from the high point, preferably polyolefin resin film, polyester resin film, polyvinyl chloride resin film, among others, from the same point, A polyolefin resin film or a polyester resin film is particularly preferred. These may be used alone or in combination of two or more if they are compatible with each other.

  Such a thermoplastic resin film can be used as a stretched or unstretched one. However, when the laminated sheet of the present invention is used for thermoforming, it is unstretched from the viewpoint of the moldability of the laminated sheet. Those are preferred. When the stretched thermoplastic resin film is used, the moldability of the laminated sheet of the present invention may be inferior. When used for thermoforming applications, among the thermoplastic resin films, polyethylene film, unstretched polypropylene film, polyvinyl chloride film and the like are preferable.

<< Polyolefin resin film >>
The polyolefin resin which is a film material of the polyolefin resin film is an olefin homo- or copolymer. Examples of the olefin include ethylene, propylene, 1-butene, isobutene, 4-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. Can be mentioned. Among these olefins, ethylene or propylene is particularly preferable. Therefore, as the polyolefin resin, polyethylene or polypropylene, or a polyethylene resin or polypropylene resin is particularly preferable in view of oil resistance and wear resistance. These may be used alone or in combination of two or more if they are compatible with each other.

  The polyolefin resin may be a copolymer of an olefin and a copolymerizable monomer (including a random copolymer, a block copolymer, etc.). Examples of such copolymerizable monomers include (meth) acrylic acid; (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate; vinyl acetate and propionic acid. Vinyl esters such as vinyl; cyclic olefins such as norbornene, ethylidene norbornene, cyclopentene, cyclopentadiene, cyclohexene; dienes such as butadiene, isoprene, 1,4-pentadiene, and the like. These copolymerizable monomers can be copolymerized with olefins alone or in combination of two or more.

<< Polyester resin film >>
The polyester resin, which is a film material of the polyester resin film, is not particularly limited as long as it contains an ester bond in the molecular chain, but “polycarboxylic acid such as dicarboxylic acid” and “polyalcohol such as diol”. A polycondensate of hydroxycarboxylic acid and / or cyclic ester; “polycarboxylic acid such as dicarboxylic acid”, “polyalcohol such as diol” and “hydroxycarboxylic acid and / or cyclic ester” And the like.

  Examples of the polyvalent carboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, and 1,6-cyclohexane. And dicarboxylic acid. These acid anhydrides may also be used, and “aliphatic dicarboxylic acid derivatives” such as lower alkyl esters thereof.

  Examples of the polyalcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Examples include diol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like.

  Particularly preferred polyester resins include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., in terms of oil resistance and abrasion resistance of the laminated sheet of the present invention. Polyethylene terephthalate is preferable.

<< Polyvinyl chloride resin film >>
Examples of the polyvinyl chloride resin which is a film material of the polyvinyl chloride resin film include polyvinyl chloride or “copolymers of vinyl chloride and other vinyl monomers”.

<< Antistatic Agent >>
The laminated sheet of the present invention has antistatic properties and / or persistent antistatic properties, and specifically has a sheet surface resistance value of 10 ⁶ Ω measured by the measurement method described in the examples in accordance with JIS K6911. preferably those which are to 10 ¹² Omega. In particular, when the laminated sheet of the present invention is used as a buffer sheet for transportation / conveyance of a glass substrate or the like, when the laminated sheet extracted from between the glass substrates or the like is easily charged, it floats when it is reused. The dust that is attached may adhere to the laminated sheet.

  The thermoplastic resin film in the present invention preferably contains an antistatic agent. The antistatic agent is not particularly limited, and examples thereof include a low molecular weight type antistatic agent such as a surfactant, and a polymer type antistatic agent. Surfactants are roughly classified into cationic, anionic, zwitterionic, and nonionic, and the most commonly used is anionic with a good balance between effect and economic efficiency. 1) fatty acid salts, 2) higher alcohol sulfates, 3) liquid fatty oil sulfates, 4) sulfates of aliphatic amines and amides, 5) aliphatic alcohol phosphates, 6) dibasic Examples thereof include fatty acid ester salts, 7) fatty acid amide sulfonates, 8) alkylaryl sulfonates, 9) formalin-condensed naphthalene sulfonates, and the like.

  Further, examples of the cationic system which is weak against heat and high in cost but has high antistatic properties include 1) aliphatic amine salts, 2) quaternary ammonium salts, and 3) alkylpyridinium salts. Furthermore, amphoteric ion systems with slightly improved heat resistance, which are weak points of anionic systems, include 1) imidazoline derivatives, 2) ammonium carboxylates, 3) ammonium sulfate esters, 4) ammonium phosphate esters, 5 ) Ammonium sulfonates and the like.

  About these antistatic agents, you may use what was made into the masterbatch. [1]: Use of a kneading type antistatic agent, [2]: Use of a coating type antistatic agent, [3]: [1] and [2]. ] And the like.

  The mass ratio of the thermoplastic resin film material of the thermoplastic resin film to the low molecular weight type antistatic agent such as a surfactant is antistatic agent / thermoplastic resin = 0.5 / 99.5 to 20/80. It is preferable to select from the range of 1/99 to 10/90. If the amount of the antistatic agent is too small, the antistatic property or the sustained antistatic property may be inferior. On the other hand, if the amount is too large, if there is no further effect, the contact material is caused by excessive bleeding out of the antistatic agent. May become contaminated.

  In the case of repeated use including cleaning, there is no particular limitation, but in particular, it is possible to prevent contact contamination due to excessive bleed out of the antistatic agent on the sheet surface. From the viewpoint of good prevention properties, polymer antistatic agents are preferred. Specifically, nonionic polymer antistatic agents such as polyether ester polymer antistatic agents, ethylene / unsaturated carboxylic acid copolymers, and the like. Preferred are anionic polymer type antistatic agents such as polymer potassium ionomer and polystyrene sulfonic acid polymer type antistatic agent, and cationic polymer type antistatic agents such as polyacrylic ester polymer type antistatic agent. It is mentioned as a thing. Of these, polyether ester polymer antistatic agents and potassium ionomers of ethylene / unsaturated carboxylic acid copolymers are preferred in terms of excellent antistatic performance, and polyether ester amide polymer antistatic agents and ethylene ( A potassium ionomer of a (meth) acrylic acid random copolymer is particularly preferred. Here, the potassium ionomer of the ethylene / (meth) acrylic acid random copolymer may contain glycerin or polyethylene glycol for the purpose of improving the antistatic performance. In addition, (meth) acrylic acid means acrylic acid or methacrylic acid.

  These high molecular weight type antistatic agents may also be used as master batches. Here, the base polymer of the masterbatch is not limited to the aliphatic polyester. [1]: Use of a kneading type antistatic agent, [2]: Use of a coating type antistatic agent, [3]: [1] and [2]. ] And the like.

  The mass ratio of the thermoplastic resin that is the film material of the thermoplastic resin film to the polymer antistatic agent is from the range of polymer antistatic agent / thermoplastic resin = 0.5 / 99.5 to 50/50. It is preferable to select, and particularly preferably 5/95 to 40/60. If the amount of the high molecular weight type antistatic agent is too small, the antistatic property and the sustained antistatic property may be inferior. On the other hand, if the amount is too large, the effect will not increase or the cost will increase. It may not be preferable. When the polymer antistatic agent is masterbatched, the mass ratio is a mass ratio of only the polymer antistatic agent excluding the base resin.

  The antistatic agent can be contained not only in the thermoplastic resin film but also in a polystyrene resin sheet. In particular, when a thermoplastic resin film is laminated only on one side of the polystyrene resin sheet, it is effective to contain it in the polystyrene resin sheet. However, antistatic without reducing the antistatic performance by containing only in the outer layer thermoplastic resin film, or by adding more in the outer layer thermoplastic resin film in the inner polystyrene resin sheet. The amount of agent used can be reduced. That is, the surface specific resistance value can be sufficiently lowered without increasing the manufacturing raw material cost. As described above, the lamination of the thermoplastic resin film imparts oil resistance, solvent resistance, abrasion resistance, etc. to the sheet, and has antistatic properties and / or continuous antistatic properties without increasing the antistatic use cost. Can be applied to sheets. The above effects are particularly prominent when the laminated sheet of the present invention is used as a buffer sheet for transportation / conveyance that requires antistatic properties and continuous antistatic properties.

  Moreover, you may add the dispersing agent with the said polymeric antistatic agent. Such a dispersant is not particularly limited, and examples thereof include a copolymer having a nonpolar unit in a molecular chain and a polar unit compatible with a polymer type antistatic agent. Examples include olefinic resins. The ratio of the dispersing agent is usually 0.01 to 20 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass in total of the thermoplastic resin and the polymer antistatic agent.

<< other substances >>
For the polystyrene resin sheet and / or thermoplastic resin film, other fillers, other dispersants, anti-blocking agents, slip agents, dispersion aids, internal lubricants, lubricants, heat, and the like are within the scope of the present invention. Stabilizer, antioxidant, hydrolysis inhibitor, ultraviolet absorber, light proofing agent, crystal nucleating agent, mold release agent, flame retardant, plasticizer, antifogging agent, reinforcing agent, extender, antibacterial agent, antifungal agent, Pigments, dyes, colorants, surface wetting improvers, fluidity improvers, thickeners, surfactants other than the above antistatic agents, inorganic fillers, organic fillers, carbon black, ketjen black, graphite, reinforcing agents “Other substances” such as

<< Thickness of thermoplastic resin film >>
The total thickness of the thermoplastic resin film is preferably 0.01 to 0.8 mm. Here, the “total thickness of the thermoplastic resin film” means (1) in the case of a laminated sheet in which a thermoplastic resin film is laminated only on one surface of the polystyrene resin sheet, the thermoplastic resin The thickness of a resin film, (2) In the case of a laminated sheet in which a thermoplastic resin film is laminated on both sides of a polystyrene resin sheet, it means the total thickness of each thermoplastic resin film laminated on both sides.

  From the viewpoint of reducing the thickness and weight, a more preferable range of “total thickness of thermoplastic resin film” is 0.015 to 0.5 mm, and a particularly preferable range is 0.02 to 0.3 mm. In the case of a laminated sheet in which a thermoplastic resin film is laminated on both sides of a polystyrene resin sheet, the preferred range of the thickness of the thermoplastic resin film on only one side is 0.005 to 0.4 mm, and the more preferred range is 0. 0.007 to 0.25 mm, and a particularly preferable range is 0.01 to 0.15 mm. The thermoplastic resin film in the present invention can realize the above-mentioned thickness while keeping other physical properties good. In particular, it is possible to ensure the stability of stretching and the strength to prevent cracking and tearing even if the thickness and weight are reduced.

  If the thickness of the thermoplastic resin film is too thin, it may be easily broken by impact or rubbing, or pinholes may occur, and the laminated sheet of the present invention has oil resistance, solvent resistance, and abrasion resistance. Etc. may be inferior. In the case of a molded product (such as a tray), it may be difficult to hold and preserve the stored food. On the other hand, when the thickness of the thermoplastic resin film is too thick, especially when used as a buffer sheet for transportation and conveyance, the bulk and stack height of the laminated sheet become high, resulting in an increase in storage space and transportation cost. May end up.

  The lamination ratio in the present invention is preferably 0.03 to 1. More preferably, it is 0.1-0.5, Most preferably, it is 0.15-0.4. If the lamination ratio is too small, the laminated sheet of the present invention may be inferior in oil resistance, solvent resistance, wear resistance and the like. On the other hand, when the lamination ratio is too large, the thickness of the entire laminated sheet is also increased, and particularly when used as a buffer sheet for transportation / conveyance, the stack height is increased, and in terms of storage space and transportation cost. Transportation efficiency may decrease. Here, “lamination ratio” in the present invention is a value obtained by dividing “total thickness of thermoplastic resin film” by “thickness of polystyrene resin sheet”. In the thickness of the thermoplastic resin film, “the total” means the sum of the thicknesses of the thermoplastic resin films laminated on both surfaces when the thermoplastic resin film is laminated on both surfaces of the polystyrene resin sheet. .

  The layer structure of the laminated sheet of the present invention is characterized in that it is a two-layer or three-layer composed of a polystyrene-based resin sheet and the thermoplastic resin film. The thermoplastic resin film may be laminated on at least one surface of the polystyrene resin sheet (preferably a surface requiring oil resistance, wear resistance, etc.), but is preferably laminated on both surfaces. .

<Heat shrinkage stress of laminated sheet>
The value of the heat shrinkage stress of the laminated sheet of the present invention is as follows: longitudinal direction (sheet extrusion direction, hereinafter sometimes referred to as “MD”), transverse direction (sheet orthogonal direction to sheet extrusion direction, hereinafter “TD”). Both are preferably 0.1 to 2 MPa. When the thermal shrinkage stress of MD or TD is less than 0.1 MPa, the sheet itself and a molded product obtained by molding the sheet may be easily broken or easily broken. On the other hand, when the heat shrinkage stress is higher than 2 MPa, the mold reproducibility (the property that the sheet faithfully reproduces the mold shape) at the time of thermoforming may be poor. Further, even when not for thermoforming, the rigidity of the sheet becomes too high, which may not be preferable in terms of flexibility and buffering properties. A more preferable range of the heat shrinkage stress is 0.2 to 1 MPa for MD and TD, and a particularly preferable range is 0.3 to 0.7 MPa.

  In the present invention, the heat shrinkage stress is the maximum load when the laminate sheet is heat shrunk using a “DN-type stress tester” manufactured by Nichi Kogyo Co., Ltd. according to ASTM D1504. It means a value (unit [MPa]) obtained by dividing the maximum load value by the cross-sectional area of the sheet before heat shrinkage.

  The heat shrinkage stress of the laminated sheet can be controlled, for example, by adjusting the roll temperature in the longitudinal stretching described above and the tenter atmosphere temperature in the lateral stretching. Specifically, by reducing the longitudinal stretching roll temperature or lowering the tenter (lateral stretching) atmosphere temperature, the thermal shrinkage stress in the longitudinal / lateral direction increases as the sheet temperature during longitudinal / lateral stretching decreases. On the contrary, when the sheet temperature during longitudinal / lateral stretching increases, the heat shrinkage stress in the longitudinal / lateral direction decreases.

  The laminated sheet of the present invention is excellent in mechanical strength (impact strength, tear strength, etc.). Impact strength and tear strength are defined as measured by the methods described in the examples. The tear strength is preferably 3.0 N / mm or more, more preferably 4.0 N / mm or more, and particularly preferably 5.0 N / mm or more. The above values can be achieved in the laminated sheet of the present invention.

  The impact strength is preferably 200 kg · cm / cm or more, more preferably 250 kg · cm / cm or more, and particularly preferably 300 kg · cm / cm or more. The above values can be achieved in the laminated sheet of the present invention. The laminated sheet of the present invention can be suitably used particularly as a buffer sheet for transportation / conveyance by satisfying the mechanical strength (impact strength and tear strength).

  The laminated sheet of the present invention is also excellent in oil resistance, solvent resistance, and wear resistance. Oil resistance, solvent resistance, and abrasion resistance are defined by those measured by the methods described in the examples. Since the laminated sheet of the present invention is formed by laminating a thermoplastic resin film having more oil resistance than polystyrene resin on the polystyrene resin sheet, the polystyrene resin depends on the oil resistance of the thermoplastic resin film. There is less erosion than the sheet alone. Preferably, the surface of the laminated sheet after the evaluation of oil resistance has no erosion and is evaluated as “good”. As for the solvent resistance, those having a “good” evaluation with no erosion on the surface of the laminated sheet after the evaluation of the solvent resistance are preferable. As for the wear resistance, the average value of the weight loss after wear test (wear resistance) is preferably less than 15 mg, more preferably less than 12 mg, and particularly preferably less than 5 mg. The above values can be achieved in the laminated sheet of the present invention.

<Method for producing laminated sheet>
The manufacturing method of the lamination sheet of this invention will not be specifically limited if it is a method of laminating | stacking the said thermoplastic resin film on a specific polystyrene-type resin sheet. Although an example of the manufacturing method of the lamination sheet of this invention is shown below, this invention is not limited to the lamination sheet manufactured with the manufacturing method.

  For example, the polystyrene-based resin sheet may be used in a twin-screw extruder while measuring a predetermined amount of other additives as necessary, for example, “(B) such as HIPS” and / or “(A) such as GPPS”. And knead and pelletize to prepare a master batch.

  Next, the above-prepared master batch, a foaming agent master batch, and if necessary, HIPS and GPPS are also weighed to form a dry blend with a blender or tumbler, and the resulting dry blend is melt-kneaded with an extruder. At this time, although depending on the viscosity of the polystyrene resin, the type of foaming agent, and the blending amount, the resin pressure is preferably 15 to 40 MPa, particularly preferably 20 to 35 MPa, and the resin temperature at the die outlet is supplied to the die. Preferably, the foamed raw fabric having a good appearance can be obtained by setting the temperature to 160 to 220 ° C, particularly preferably 180 to 200 ° C. Next, biaxial stretching is successively performed successively, for example, by longitudinal stretching by a roll stretching method or the like, followed by transverse stretching by a tenter method or the like. On the way, it is preferable that the sheet continuously extruded and foamed from the outlet of the die is rapidly cooled with a cooling roll or the like, reheated with a heating roll, and then biaxially stretched. Next, the biaxially stretched product is preferably wound into a roll with a winder or the like.

  Similarly to the above, the thermoplastic resin film is made into a dry blend while measuring a predetermined amount of the film raw material and, if necessary, an antistatic agent and other various additives, and then melt-kneaded by an extruder. At this time, depending on the type of the antistatic agent, a commercially available master batch may be used, or a commercially available product may be used as it is.

  The laminated sheet of the present invention may be obtained by coextruding the obtained polystyrene-based resin sheet and thermoplastic resin film using a general-purpose die with a feed block, a multi-manifold die, or the like. Is laminated by a method such as dry lamination or the like, and the laminated sheet of the present invention is imparted with good oil resistance, solvent resistance, and abrasion resistance, and the adhesion between the polystyrene resin sheet and the thermoplastic resin film is It is preferable in terms of good points.

For example, when the laminated sheet of the present invention is used as a buffer sheet for transportation and conveyance, a release agent may be applied before winding into a roll after stretching. The coating method is not particularly limited. For example, a dimethyl silicone emulsion containing a dimethyl silicone oil having a viscosity of 1000 to 20000 mm ² / s and an emulsifier at 25 ° C. is used as an aqueous solution having a solid content concentration of about 0.1 to 5% by mass. A coating method using a spray coater, an air knife coater, a squeeze roll coater, a gravure roll coater, a knife coater or the like, and drying with a hot air dryer or the like is preferred. An antistatic agent may be mixed with the release agent, and the mixing ratio is about 30 to 80% by mass with respect to the total amount with the silicone oil (solid content).

  In the release agent, as long as the effect of the present invention is not impaired, an antistatic agent other than the above, an antiblocking agent, a viscosity modifier, an antifoaming agent, an ultraviolet absorber, an anticoloring agent, Various additives such as antibacterial agents, pigments and dyes can be blended.

  The laminated sheet of the present invention can be molded into molded products such as electronic component trays, food trays, and medical kits by thermoforming. There is no limitation on the thermoforming method, and conventionally known methods such as a vacuum forming method, a pressure forming method, and a differential pressure forming method combining a vacuum forming method and a pressure forming method are exemplified. When using for the said thermoforming use, it is preferable to use the unstretched thermoplastic resin film from the point of a moldability. As the thermoplastic resin film for use in thermoforming, a polyethylene film, an unstretched polypropylene film, a polyvinyl chloride film, and the like are particularly suitable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example, unless the summary is exceeded. As the raw material, a commercial product having the following characteristics is used, and the evaluation items of the laminated sheet are as follows.

<Raw materials>
Raw material of polystyrene resin sheet (hereinafter sometimes referred to as “base layer”) [(A) polystyrene resin not having rubber component]
1. GPPS: manufactured by General Polystyrene PS Japan Co., Ltd., trade name: HH102, temperature 200 ° C., melt flow rate at a load of 5 kg (hereinafter referred to as “MFR (200 ° C., 5 kg)”) is 3.5 g / 10 min. is there.

[(B) Polystyrene resin having a rubber component]
2. HIPS: made of impact-resistant polystyrene PS Japan, trade name: HT478, MFR (200 ° C., 5 kg) is 3.0 g / 10 min.

[Foaming agent]
3. FA-1: Effervescent agent manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name: Polyslen ES405, decomposition temperature 155 ° C., PS-based 40% by mass masterbatch type, Poly-Ekyo registered product.

Raw material of thermoplastic resin film (hereinafter sometimes referred to as “surface layer”) [thermoplastic resin]
4). PP-1:
Biaxially stretched polypropylene (Antistatic type with antistatic agent)
Toyobo Co., Ltd., trade name: Pyrene Film-OT P2161 (AS)
5). PP-2:
Biaxially stretched polypropylene film (permanent antistatic type with antistatic agent)
Product name: PAS-C1 manufactured by Futamura Chemical Co., Ltd.
6). PE-1:
Linear low density polyethylene film (Antistatic type with antistatic agent)
Product name: LA-7, manufactured by Tamapoli
7). PE-2:
Linear low density polyethylene film (permanent antistatic type with antistatic agent)
Product name: STAT-3S, manufactured by Technostat Kogyo Co., Ltd.
8). PET-1:
Biaxially stretched polyethylene terephthalate film (Antistatic type with antistatic agent)
Product name: Espet Film E7410, manufactured by Toyobo Co., Ltd.

<Evaluation items>
(1) Tear strength (unit: N / mm)
From the laminated sheets obtained in the following Examples and Comparative Examples, test pieces having a size of 50 mm × 64 mm, 5 sheets each having MD (sheet extrusion direction) as the long side, and TD (sheet extrusion direction) Five sheets were made with the long side as the long side. An incision of 13 mm is cut from the central edge of the end side (50 mm) side of these test pieces in parallel with the long side, and the indicated value when torn using a “light load tear tester” manufactured by Toyo Seiki Co., Ltd. A value obtained by dividing the indicated value by the thickness [mm] of the initial test piece was taken as the tear strength (unit: N / mm). About MD and TD, the average value in five test pieces made into each long side was computed, and the total average value was computed from both average values. When this value is 3.0 N / mm or more, the tear strength is determined as “good” and indicated as “◯”, and when the value is less than 3.0 N / mm, it is determined as “inferior” and indicated as “x”. did.

(2) Impact strength (unit: kg · cm / cm)
Five test pieces having a size of 100 mm × 100 mm were prepared from the laminated sheets obtained in the following examples and comparative examples, and “Puncture tester (tip is 12.7 mm round) manufactured by Toyo Seiki Co., Ltd. in accordance with JIS P8134. Using a spherical head), the amount of energy required for breaking the test piece (impact strength: kg · cm) was read from the scale plate of the puncture tester. The value obtained by dividing the amount of energy by the sheet thickness (cm) was taken as impact strength (puncture impact strength, unit: kg · cm / cm), and an average value of five test pieces was calculated. This average value was defined as impact strength. When this value is 200 kg · cm / cm or more, the impact strength is judged as “good” and indicated as “◯”, and when it is less than 200 kg · cm / cm, it is judged as “poor” and indicated as “x”. did.

(3) Abrasion resistance (unit: mg)
From the laminated sheets obtained in the following examples and comparative examples, five disk-type test pieces having a diameter of 100 mm were prepared, and a “taper wear tester” manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7204 was used. The weight loss after the wear test was measured under the conditions of a test rotation speed of 1000 rotations, a test load of 4.90 N, and a wear wheel CS10, and the measured value was defined as wear resistance (unit: mg). The average value of was calculated. This average value was defined as wear resistance. When this value was less than 15 mg, the wear resistance was judged as “good” and displayed as “◯”, and those with 15 mg or more were judged as “poor” and displayed as “x”.

(4) Oil resistance From the laminated sheets obtained in the following examples and comparative examples, a test piece having a size of 25 mm × 70 mm was prepared, bent to a bending radius of 25 mm in the 70 mm direction of the test piece, and the center portion of the sheet ( When thermoplastic resin films are laminated, about 0.1 mL of medium-chain fatty acid triglyceride (MCT) (trade name: Coconut MT) manufactured by Kao Corporation is dropped on these sheet surfaces, and left for 30 minutes. The condition of the sheet was visually confirmed. The visual erosion degree of the sheet was defined as oil resistance. As the degree of erosion of the sheet increases, cracks having a length of 2 mm or more can be confirmed when visually confirmed. As erosion progresses, the sheet breaks or breaks. If there is no erosion, any of the above cracks, folds, and breaks cannot be visually confirmed. A sheet having no erosion on the sheet surface was determined as “good” and indicated as “◯”, and a sheet having erosion on the sheet surface was determined as “inferior” and indicated as “x”.

(5) Solvent resistance From the laminated sheets obtained in the following examples and comparative examples, a test piece having a size of 25 mm × 70 mm was prepared, bent to a bending radius of 25 mm in the 70 mm direction of the test piece, and the center of the sheet About 0.1 ml of toluene was dropped onto (if the polyolefin or polyester film was laminated) on the film surface, and left for 30 minutes to visually check the state of the sheet. The degree of visual erosion of the sheet was defined as solvent resistance. As the degree of erosion of the sheet increases, cracks having a length of 2 mm or more can be confirmed when visually confirmed. As erosion progresses, the sheet breaks or breaks. If there is no erosion, any of the above cracks, folds, and breaks cannot be visually confirmed. A sheet having no erosion on the sheet surface was determined as “good” and indicated as “◯”, and a sheet having erosion on the sheet surface was determined as “inferior” and indicated as “x”.

(6) Surface resistance (unit: Ω)
Five test pieces having a size of 100 mm × 100 mm were prepared from the laminated sheets obtained in the following examples and comparative examples, and the state was adjusted at 23 ° C. and a relative humidity of 50% for 24 hours. Thereafter, in accordance with JIS K6911, the surface resistance value (under the conditions of 23 ° C., 50% RH, using “High Lester UP MCP-450” manufactured by Mitsubishi Chemical Corporation under the conditions of an applied voltage of 500 V and a measurement time of 60 seconds ( Unit: Ω) was measured, and the average value of five test pieces was calculated. This average value was taken as the surface resistance value of the sheet. Furthermore, these five test pieces were washed with running water at 60 ° C. for 3 minutes, wiped with clean paper, conditioned for 24 hours at 23 ° C. and 50% relative humidity, and then subjected to surface resistance under the same conditions as before washing. The value was measured, and the average value was calculated as the surface resistance value after cleaning. This value is antistatic ones of 10 ⁶ to 10 ¹² range is determined as good displays "○", labeled "×" what exceeds ¹⁰¹² determines "poor".

(7) Moldability Laminate sheets obtained in the following examples and comparative examples were heated and heated using a pressure plate molding machine (manufactured by Kansai Automatic Molding Machine Co., Ltd., PK-450 type), and the opening shape was 200 mm × 120 mm. A container molding die having a rectangular shape with a bottom shape of 190 mm × 110 mm and a depth of 25 mm was attached, and molding was performed such that the thermoplastic resin film laminated surface was inside the container. The molding test was carried out under the conditions of a hot plate temperature of 128 ° C., a heating time of 2.0 seconds, a heating pressure of 0.1 MPa, a molding time of 1.0 seconds, and a molding pressure of 0.39 MPa. The appearance was visually confirmed. The result of this visual confirmation was defined as moldability. The shape of the mold of the molded body is clearly shown, and it is judged as good if there is no tearing or peeling of the laminated film, and the shape of the mold of the molded body does not appear clearly A thing with a thing, a tear, and peeling of a laminated | multilayer film was determined to be inferior, and "x" was displayed.

Example 1
Prepare a T-die (manufactured by Plastic Giken Co., Ltd.) with a surface length of 850 mm through an extruder (Plastic Giken Co., Ltd., vent type 65 mmφ type extruder) and a connecting tube attached to the tip of the extruder. Were assembled to obtain a sheet. HIPS and a foaming agent were uniformly mixed by the ribbon blender in the ratio of Table 1, and the dry blend was obtained. The dry blend was melted by setting the cylinder temperature of the extruder to about 190 ° C., extruded as an unstretched sheet, and rapidly cooled with a cooling roll set at 80 ° C. to produce an unstretched foamed sheet. The obtained unstretched sheet was stretched about 2.5 times in the longitudinal direction by a roll type longitudinal stretching machine, and then stretched about 2.5 times in the transverse direction by a tenter lateral stretching machine, and the thickness was 0.34 mm, and the foaming ratio was 1 .70 biaxially stretched and foamed polystyrene-based resin sheet was wound into a roll.

  Next, using a polyether polyurethane adhesive (manufactured by Dainichi Seika Kogyo Co., Ltd., Seika Bond A-342, C-93), the above biaxially stretched and foamed polystyrene resin sheet and the PP-1 film described in Table 1 were dried. Lamination was performed using a laminator to obtain a laminated sheet having a thickness of 0.37 mm. Table 1 shows the layer structure of the obtained sheet, the sheet thickness, the rubber content, the expansion ratio, and the evaluation results on the physical property evaluation items (1) to (7).

Example 2
In Example 1, a laminated sheet having a thickness of 0.38 mm was obtained in the same manner as in Example 1 except that the polystyrene-based resin and the thermoplastic resin described in Table 1 were used. The evaluation results are shown in Table 1.

Example 3
In Example 2, the film forming speed condition was changed, and a biaxially stretched and foamed polystyrene resin sheet having a thickness of 0.11 mm and an expansion ratio of 2.50 was used. A 15 mm laminated sheet was obtained. The evaluation results are shown in Table 1.

Example 4
In Example 1, a laminated sheet having a thickness of 0.48 mm was obtained in the same manner as in Example 1 except that the polystyrene-based resin and the thermoplastic resin listed in Table 1 were laminated on both sides. The evaluation results are shown in Table 1.

Example 5
In Example 4, a laminated sheet having a thickness of 0.53 mm was obtained in the same manner as in Example 4 except that the polystyrene-based resin and the thermoplastic resin shown in Table 1 were used. The evaluation results are shown in Table 1.

Example 6
In Example 4, a laminated sheet having a thickness of 0.47 mm was obtained in the same manner as in Example 4 except that the polystyrene-based resin and the thermoplastic resin described in Table 1 were used. The evaluation results are shown in Table 2.

Example 7
In Example 1, a laminated sheet having a thickness of 0.44 mm was obtained in the same manner as in Example 1 except that the polystyrene-based resin and the thermoplastic resin described in Table 1 were used. The evaluation results are shown in Table 2.

Example 8
In Example 7, only the film forming speed condition was changed, a 0.09 mm thick, biaxially stretched polystyrene resin sheet having an expansion ratio of 1.24 was used, except that the thermoplastic resin described in Table 1 was used. In the same manner as in Example 7, a laminated sheet having a thickness of 0.13 mm was obtained. The evaluation results are shown in Table 2.

Comparative Example 1
In Example 1, a thickness of 0 was obtained in the same manner as in Example 1 except that an unstretched expanded polystyrene resin sheet that did not stretch in the longitudinal direction and the lateral direction was used instead of the biaxially stretched expanded polystyrene resin sheet. A laminated sheet of 43 mm was obtained. The evaluation results are shown in Table 3.

Comparative Example 2
In Example 1, the cylinder temperature of the extruder was set to 230 ° C. instead of about 190 ° C., and a polystyrene resin sheet having a foaming ratio of 4.10 times and a thickness of 0.25 mm was used. Similarly, a laminated sheet having a thickness of 0.28 mm was obtained. The evaluation results are shown in Table 3.

Comparative Example 3
In Example 1, a laminated sheet having a thickness of 0.34 mm was obtained in the same manner as in Example 1 except that the PP-1 film was not laminated on the biaxially stretched polystyrene resin sheet with a dry laminator. The evaluation results are shown in Table 3.

From the above Examples 1 to 8 and Comparative Examples 1 to 3, the following became clear.
(1) Each of the laminated sheets obtained in Examples 1 to 8 is a laminated sheet that satisfies the requirements of claim 1 and is excellent in oil resistance, solvent resistance, wear resistance, and the like, and the thickness of the sheet. Although it was thin, it was a styrene resin laminated sheet excellent in mechanical strength (impact strength, tear strength, etc.).
Moreover, the lamination sheet obtained using the unstretched thermoplastic resin film was further excellent in moldability (Example 2, Example 3, and Example 8). In addition, when what was extended | stretched as a thermoplastic resin film was used, the moldability was bad, but the moldability improved when it replaced with the unstretched thing.

(2) On the other hand, the laminated sheet using the polystyrene-based resin sheet that is not stretched (Comparative Example 1) is inferior in mechanical strength (impact strength, tear strength, etc.) despite the thicker sheet thickness than in Example 1. A laminated sheet was obtained.
(3) In addition, a laminated sheet using a polystyrene resin sheet having a foaming ratio larger than 4.0 times (Comparative Example 2) is inferior in mechanical strength (impact strength, tear strength, etc.) to Example 1 due to excessive foaming. It was a laminated sheet.
(4) Further, using a biaxially stretched and foamed polystyrene-based resin sheet stretched so that the expansion ratio is 1.1 to 4.0 times and at least one of the expansion ratios is 3.0 times or less. In addition, a laminated sheet in which a thermoplastic sheet having more oil resistance than that of the polystyrene resin is not laminated on the polystyrene resin sheet (Comparative Example 3) was a laminated sheet inferior in oil resistance, solvent resistance, abrasion resistance, and the like.

  The laminated sheet of the present invention is excellent in oil resistance, solvent resistance, abrasion resistance, etc., and is widely used because it has excellent mechanical strength (impact strength, tear strength, etc.) even though the sheet is thin. It can be done. In particular, it can be widely used as a buffer sheet for transporting and transporting plate-like members (for example, glass, display panels using glass, building members provided with decoration, etc.). Further, the laminated sheet of the present invention can be subjected to secondary molding by hot plate molding, and can be widely and suitably used as a tray for electronic parts, a food tray, a medical tray used in a medical kit, and the like. it can.

Claims (7)

  A thermoplastic resin that is more oil resistant than a polystyrene resin on a polystyrene resin sheet that has been expanded so that the expansion ratio is 1.1 to 4.0 times and at least one of the expansion ratios is 3.0 times or less. A laminated sheet having a layer structure of two or three layers formed by laminating films.   The laminated sheet according to claim 1, wherein the thermoplastic resin film is more wear resistant than a polystyrene resin.   The laminated sheet according to claim 1 or 2, wherein the thermoplastic resin film is a polyolefin resin film or a polyester resin film.   The thickness of the said polystyrene-type resin sheet is 0.05-0.8 mm, and the sum total of the thickness of this thermoplastic resin film is 0.01-0.8 mm, Any of Claim 1 thru | or 3 The laminated sheet according to any of the claims.   The laminated sheet according to any one of claims 1 to 4, wherein the lamination ratio, which is a value obtained by dividing the total thickness of the thermoplastic resin film by the thickness of the polystyrene resin sheet, is 0.03 to 1. .   The laminated sheet according to any one of claims 1 to 5, wherein the thermoplastic resin film contains an antistatic agent.   The laminated sheet according to any one of claims 1 to 6, wherein the content of the rubber component in the polystyrene-based resin sheet is 20% by mass or less.