JP2020079348A - Impact resistant polystyrene-based resin sheet, and molded product thereof - Google Patents

Abstract

To provide an impact resistant polystyrene-based resin sheet exerting excellent mechanical physical properties such as impact resistance, even when a heat resistant polystyrene-based resin is mixed with the impact resistant polystyrene-based resin.SOLUTION: The impact resistant polystyrene-based resin sheet is provided which includes, as a main component, a resin composition of an impact resistant polystyrene-based resin (A) and a heat resistant polystyrene-based resin (B), and which satisfies the following (i) to (iii). (i) a composition ratio (A)/(B) is 50 to 99 mass%/50 to 1 mass%, when a total of the resin (A) and the resin (B) is 100 mass%, (ii) a Vicat softening point of the resin (B) is 106°C or higher, (iii) MFR (A) of the resin (A) and MFR (B) of the resin (B) satisfy the formula (1). MFR (B) -MFR (A)≥-1.0 (unit:g/10 min)... formula (1).SELECTED DRAWING: None

Description

  The present invention relates to an impact-resistant polystyrene-based resin sheet, and a molded product such as a box-shaped container body, a container with a lid, a container without a lid such as a cup, tray, and plate, a container such as a lid, and the like using the sheet.

A transparent biaxially stretched polystyrene resin sheet made of general-purpose polystyrene resin (GPPS) or the like is used as a molded product such as a food packaging container or a lid material from the viewpoint of rigidity, lightness, transparency, moldability and recyclability. ing.
Further, even in the case of an unstretched sheet of a impact-resistant polystyrene resin (HIPS) such as a rubber-modified polystyrene-based resin or a biaxially stretched sheet, the rigidity, the lightness, the moldability, etc. are excellent, and compared with the above-mentioned transparent sheet, Due to its excellent oil resistance and impact resistance, it is a box-shaped container body for storing food such as fresh food, dried food, confectionery, a container with a lid, a container without a lid such as a cup, tray, plate, lid, etc. (Hereinafter referred to as "container") is used as a raw material sheet for manufacturing.

  As an example of such a sheet, Patent Document 1 discloses a biaxially stretched impact-resistant polystyrene composed of a mixture of a graft-type rubber-modified polystyrene and a polystyrene for general use, in which a stretch ratio and a heat shrinkage stress are defined in a specific range. Sheets are disclosed. Further, in Patent Documents 2 and 3, a biaxially stretched styrene-based resin sheet composed of an impact-resistant styrene-based resin composition containing a styrene-based graft copolymer and a styrene-based resin in a specific weight ratio, a synthesis A resin sheet is disclosed.

In the case of molding the above-mentioned container or the like, a sheet is molded into a predetermined shape and then punched to obtain a product. On the other hand, the remaining punched-out portion (skeleton) is crushed for recycling and reused, mixed with virgin pellets, and melt-extruded again to form a sheet.
At this time, the transparent polystyrene-based resin sheet, and the skeleton of the impact-resistant polystyrene-based resin sheet is used for re-extrusion of the impact-resistant polystyrene-based resin sheet in which transparency is not important from the viewpoint of discoloration and resin burning. Often. Further, at the time of recycling, rubber components and the like may be further added as needed.

  For example, in Patent Document 4, polystyrene resin 20 to 76% by mass, high impact polystyrene resin 20 to 50% by mass, styrene-conjugated diolefin thermoplastic elastomer 1 to 5% by mass, styrene-butadiene-butylene-styrene system. A polystyrene resin sheet containing 3 to 25 mass% of a thermoplastic elastomer as an essential component and a packaging container formed by thermoforming the sheet are disclosed.

  On the other hand, with regard to transparent biaxially stretched polystyrene-based resin sheets, in recent years, high-power microwave ovens used for business such as convenience stores have become widespread, and products using microwave ovens such as chilled lunch boxes have been developed. Therefore, food packaging containers and lids have been strongly required to have heat resistance for suppressing deformation of sheet molded products due to heating in a microwave oven.

  As a technique for improving the heat resistance of the sheet itself for suppressing the deformation of the sheet molded article due to heating in a microwave oven, for example, a styrene-methacrylic acid-methyl methacrylate resin as disclosed in Patent Document 5 is used. An extruded sheet, a biaxially stretched sheet containing a styrene-methacrylic acid-methyl methacrylate copolymer resin and an impact-resistant styrene-based resin as in Patent Document 6, and a multi-branched sheet as in Patent Document 7 A styrene-based resin sheet containing a multi-branched copolymer obtained by copolymerizing a macromonomer, a styrene-based monomer and methacrylic acid, and a copolymer obtained by copolymerizing a styrene-based monomer and methacrylic acid. It is disclosed.

JP, 2007-237732, A JP, 2005-200572, A JP 2000-336182 A JP, 2008-115317, A JP, 2011-126996, A JP, 2005-021074, A JP, 2016-030817, A

However, in the styrene-based copolymer resin sheet in which methacrylic acid or the like is copolymerized as disclosed in Patent Documents 5 to 7, those skeletons are recycled and mixed with impact-resistant polystyrene-based resin to form a sheet. In this case, it was found that the impact resistance of the obtained impact-resistant polystyrene-based resin sheet was dramatically reduced as compared with the case where the skeleton of the general-purpose polystyrene resin sheet was used for recycling.
Further, the high-impact polystyrene-based resins such as graft-type rubber-modified polystyrene and styrene-based graft copolymers disclosed in Patent Documents 1 to 4 and polystyrene resins mixed with impact-resistant polystyrene-based resins are all general-purpose polystyrene. An impact-resistant polystyrene-based resin sheet that is a resin and contains a heat-resistant styrene-based resin in which a methacrylic acid monomer or the like is copolymerized has not been established.

  The present invention has been made in view of the above problems, and even when a heat-resistant polystyrene-based resin is mixed with an impact-resistant polystyrene-based resin, an impact-resistant polystyrene-based resin sheet having excellent mechanical properties such as impact resistance is provided. It is an object of the present invention to provide a molded article such as a container using the sheet.

  As a result of diligent studies by the present inventors, when the heat-resistant polystyrene-based resin having a Vicat softening point of 106° C. or higher is contained, the melt flow rate of the impact-resistant polystyrene-based resin and the heat-resistant polystyrene-based resin has a specific relationship. It has been found that the above improves the compatibility of the two and provides effective physical properties such as impact resistance.

  That is, the technical design for recycling the skeleton of the heat-resistant polystyrene-based resin was thoroughly studied, and even if the impact-resistant polystyrene-based resin and the heat-resistant polystyrene-based resin were mixed in a wide range of mass ratios, the impact resistance that suppressed deterioration of various physical properties was suppressed. The following has been completed by finding a polystyrene resin sheet and a molded product using the sheet.

A first aspect of the present invention is an impact-resistant polystyrene-based resin sheet containing a resin composition of an impact-resistant polystyrene-based resin (A) and a heat-resistant polystyrene-based resin (B) as a main component, which comprises: ) To (iii) are satisfied, the impact-resistant polystyrene-based resin sheet is characterized.
(I) The composition ratio (A)/(B) is 50 to 99% by mass/50 when the total amount of the impact-resistant polystyrene-based resin (A) and the heat-resistant polystyrene-based resin (B) is 100% by mass. ~ 1% by weight,
(Ii) the heat-resistant polystyrene resin (B) has a Vicat softening point of 106° C. or higher,
(Iii) The melt flow rate MFR(A) of the high impact polystyrene resin (A) and the melt flow rate MFR(B) of the heat resistant polystyrene resin (B) satisfy the equation (1).
MFR(B)−MFR(A)≧−1.0 [unit: g/10 min]...Equation (1)

  In the first embodiment, it is preferable that the MFR(B) is 1.5 g/10 min or more.

  In the first embodiment, the heat-resistant polystyrene-based resin (B) includes a styrene-based monomer (a), a styrene-based monomer of a different type from the (a), (meth)acrylic acid, and (meth)acrylic. A binary copolymer with one monomer (b) selected from the group of acid esters, maleic anhydride, and acrylonitrile, or a styrene-based monomer (a) and a different type from the above (a) A styrene-based monomer, (meth)acrylic acid, maleic anhydride, and one kind of monomer (b)′ selected from the group of acrylonitrile, and a (meth)acrylic acid ester monomer (c) It is preferably a terpolymer.

  The composition ratio of the binary copolymer is such that (a) is 80 to 99 mass %, (b) when the total amount of the monomer (a) and the monomer (b) is 100 mass %. Is preferably 1 to 20% by mass.

  The composition ratio of the terpolymer is such that when the total amount of the monomer (a), the monomer (b)′ and the monomer (c) is 100% by mass, (a) is It is preferable that 60 to 98% by mass, (b)' is 1 to 20% by mass, and (c) is 1 to 20% by mass.

  A second aspect of the present invention is a molded article made of the impact resistant polystyrene resin sheet of the first aspect.

  According to the present invention, it is possible to obtain an impact-resistant polystyrene-based resin sheet having excellent impact resistance and tear strength even when the impact-resistant polystyrene-based resin and the heat-resistant polystyrene-based resin are mixed in a wide range of mass ratios. Therefore, the skeleton of the heat-resistant polystyrene-based resin sheet can be mixed with the impact-resistant polystyrene-based resin for recycling. Further, the obtained sheet can be suitably used as a molded product such as a box-shaped container body, a container with a lid, a container without a lid such as a cup, a tray, a plate, and a container such as a lid.

  Hereinafter, the impact-resistant polystyrene-based resin sheet of the present invention (hereinafter, also referred to as the sheet of the present invention) as an example of the embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

In addition, in this invention, a "main component" means the component which accounts for the most mass ratio in the resin composition which comprises, It is preferable that it is 50 mass% or more and 100 mass% or less, and 70 mass% or more. Is more preferable, and 90% by mass or more is further preferable.
In addition, when described as “X to Y” (X and Y are arbitrary numbers), “preferably larger than X” and “preferably smaller than Y” together with the meaning of “X or more and Y or less” unless otherwise specified. Is included.

<High impact polystyrene resin sheet>
The impact-resistant polystyrene-based resin sheet of the present invention contains a resin composition of the impact-resistant polystyrene-based resin (A) and the heat-resistant polystyrene-based resin (B) as a main component.

(Impact-resistant polystyrene resin (A))
As the impact-resistant polystyrene-based resin (A) in the present invention, a rubber component described below is graft-polymerized with a styrene-based monomer described below (hereinafter referred to as “graft-type HIPS”). In some cases) can be used. The graft type HIPS can be formed, for example, by dissolving a rubber component in a styrene-based monomer and then graft-polymerizing the rubber component with the styrene-based monomer. It is preferable to form a salami structure dispersed in. In the salami structure, the rubber component and part of the polystyrene outside salami are bonded.

  The impact-resistant polystyrene-based resin (A) is obtained by kneading polystyrene obtained by polymerizing a styrene-based monomer described below and a rubber component described below (hereinafter, referred to as " "Blend type HIPS" may be used). Polystyrene can be obtained by bulk polymerization or suspension polymerization of a styrene-based monomer. As the kneading method, heat kneading using a general-purpose kneader such as a single-screw or multi-screw extruder or a Banbury mixer can be adopted.

  The graft type HIPS can be obtained by polymerizing at least a styrene-based monomer in the presence of a rubber component. Examples of the rubber component include polybutadiene, polyisoprene, chloroprene rubber, styrene-isoprene copolymer, styrene-isoprene-butadiene copolymer, and random or block polymer of butadiene and other copolymerizable monomer. it can. Examples of monomers copolymerizable with butadiene include vinyl aromatic compounds such as styrene and α-methylstyrene, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, and esters thereof, vinyl such as acrylonitrile and methacrylonitrile. Cyan compounds can be mentioned.

  Further, these rubber components may be used alone or in combination of two or more kinds. Of the rubber components, diene rubbers are preferable, and polybutadiene, polyisoprene, random or block styrene-butadiene copolymers are particularly preferable. The styrene content in this styrene-butadiene copolymer is preferably 10 to 50% by mass, more preferably 10 to 30% by mass. The rubber component is particularly preferably high cis polybutadiene having a cis 1,4 structure of 90 mol% or more from the viewpoints of thermal stability and recyclability when the impact-resistant polystyrene resin (A) is used.

  Examples of the styrene-based monomer to be graft-polymerized include styrene, for example, alkylstyrene such as o-, m-, p-methylstyrene, p-ethylstyrene, and pt-butylstyrene, for example, α-methylstyrene, Examples thereof include vinyl aromatic compounds such as α-alkylstyrene such as α-ethylstyrene. These styrene-based monomers may be used alone or in combination of two or more. Of these, styrene is preferable.

  The diene content in the rubber component contained in the high impact polystyrene resin (A) in the present invention is preferably 2.0% by mass to 12.0% by mass. Further, the diene content in the rubber component is more preferably 3.0% by mass to 12.0% by mass, and further preferably 4.0% by mass to 12.0% by mass.

  When the diene content in the rubber component is 2.0% by mass or more, the high-speed moldability during thermoforming is improved, and the impact-resistant polystyrene-based resin sheet of the present invention and the impact resistance of the molded product are Tear strength is easily improved, which is preferable. Further, it is preferable that the diene content in the rubber component is 12.0% by mass or less because the impact-resistant polystyrene-based resin sheet of the present invention and the molded article can easily maintain the rigidity.

  The diene content in the rubber component can be measured by potentiometric titration using iodine monochloride, potassium iodide and sodium thiosulfate standard solution. The analysis method is described, for example, in “Polymer Analysis Handbook”, edited by Japan Society for Analytical Chemistry, “New Edition Polymer Handbook”, Kinokuniya Bookstore (1995 edition), P. It is described in "(3) Rubber content" of 659 and can be measured by this method.

  The average particle size of the rubber component contained in the high impact polystyrene resin (A) in the present invention is not limited, but preferably 0.5 μm to 10.0 μm. When the average particle diameter is in the above range, the impact resistance and tear strength of the impact resistant polystyrene resin sheet and the molded product in the present invention are easily improved, which is preferable. The average particle size of the rubber component contained in the impact-resistant polystyrene-based resin (A) is more preferably 1.0 μm to 8.0 μm, further preferably 2.0 μm to 6.0 μm.

The average particle diameter of the rubber component is obtained by taking a 10,000 times magnified photograph using a transmission electron microscope by the ultrathin section method, measuring the particle diameter of about 1000 particles of the rubber component photographed, and using the following formula: , Rubber average particle diameter [μm]=(ΣniDi ⁴ )/(ΣniDi ³ ). In this equation, ni represents the number of rubber particles having a particle diameter of Di. Moreover, since the particles of the rubber component are not perfectly circular, the major axis and the minor axis were measured, and the average particle diameter was calculated by arithmetic average.

  Although the melt flow rate (MFR) of the impact-resistant polystyrene resin (A) in the present invention is not limited, it is usually preferably 0.5 g/10 min to 20 g/10 min at a temperature of 200° C. and a load of 5 kgf. More preferably, it is 0.0 g/10 min to 10 g/10 min.

The melt flow rate of the impact-resistant polystyrene-based resin (A) (hereinafter sometimes referred to as MFR(A)) is the melt-flow rate of the heat-resistant polystyrene-based resin (B) (hereinafter referred to as MFR(B)). However, it is preferably not too large and equal to or less than the above, and more preferably a value smaller than MFR(B). For example, MFR(B) and MFR(A) preferably satisfy the formula (1), more preferably the formula (2), and even more preferably the formula (3).
MFR(B)−MFR(A)≧−1.0 [unit: g/10 min]...Equation (1)
MFR(B)−MFR(A)≧−0.5 [unit: g/10 min]...Equation (2)
MFR(B)-MFR(A)≧0.0 [unit: g/10 min]...Equation (3)

Further, the upper limit of MFR(B)-MFR(A) is not particularly limited, but it is generally preferable that the following formula (4) is satisfied.
MFR(B)-MFR(A)≦10 [unit: g/10 min]...Equation (4)
By satisfying the expression (1), the domain size of the heat-resistant polystyrene-based resin (B) can be reduced and the reduction in the mechanical strength of the sheet can be easily suppressed, which is preferable. Further, by satisfying the expression (4), it is easy to suppress appearance defects due to uneven mixing of sheets, which is preferable.

(Heat-resistant polystyrene resin (B))
The heat-resistant polystyrene-based resin (B) in the present invention is a resin containing the styrene-based monomer (a) as a main component and has a Vicat softening point of 106° C. or higher.
When the heat-resistant polystyrene-based resin (B) is a copolymer, and the styrene-based monomer (a) is the main monomer component, a multi-component copolymer containing at least one other monomer component But it's okay. Further, the copolymer may be any copolymer form such as a random copolymer, a block copolymer, a graft copolymer and the like.
The heat-resistant polystyrene-based resin (B) may be a linear polystyrene-based resin or a multi-branched polystyrene-based resin. The heat-resistant polystyrene-based resin (B) used in the sheet of the present invention may be one kind or a mixture of two or more kinds.

  Examples of the styrene-based monomer (a) include styrene and its derivatives. For example, styrene, α-methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, and other alkylstyrenes, fluorostyrene, chlorostyrene, bromostyrene. Examples thereof include halogenated styrene such as styrene, dibromostyrene and iodostyrene, nitrostyrene, acetylstyrene, methoxystyrene and the like. Among them, styrene and α-methylstyrene are preferably used from the viewpoint of compatibility with the impact-resistant polystyrene resin (A).

Examples of other monomers used in the copolymer include styrene-based monomers of a different type from (a), (meth)acrylic acid, (meth)acrylic acid ester, maleic anhydride, acetic acid. Vinyl, acrylonitrile, and conjugated diene hydrocarbons such as butadiene, isoprene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene, Examples include α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene.
Among them, from the viewpoint of improving the Vicat softening point of the heat-resistant polystyrene-based resin (B), the other monomer used in the copolymer is α-methylstyrene which is a styrene-based monomer of a different type from (a). , (Meth)acrylic acid, (meth)acrylic acid ester, maleic anhydride, and acrylonitrile are preferably used, and α-methylstyrene, (meth)acrylic acid, and (meth)acrylic acid ester are more preferably used. Particular preference is given to using (meth)acrylic acid.

  Here, "a styrene-based monomer different from (a)" means, for example, when styrene is used as the styrene-based monomer (a), a styrene-based monomer other than the styrene. , For example, α-methylstyrene, dimethylstyrene and the like.

Moreover, as said (meth)acrylic acid ester, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, t (meth)acrylate -Butyl, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, stearyl (meth)acrylate, octadecyl (meth)acrylate, ( Phenyl (meth)acrylate, benzyl (meth)acrylate, chloromethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2,3,4,5-Tetrahydroxypentyl (meth)acrylate, aminoethyl (meth)acrylate, propylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, ethylamino (meth)acrylate Examples thereof include propyl, phenylaminoethyl (meth)acrylate, cyclohexylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.
Among them, methyl (meth)acrylate is used as the other monomer used in the copolymer from the viewpoint of suppressing appearance defects and suppressing mechanical strength deterioration due to dehydration reaction during molding of impact-resistant polystyrene resin sheet. Is preferred.

  When the heat-resistant polystyrene-based resin (B) is a copolymer, a styrene-based monomer (a) and a styrene-based monomer of a different type from (a), (meth)acrylic acid, (meth)acrylic A binary copolymer with one type of monomer (b) selected from the group consisting of acid esters, maleic anhydride, and acrylonitrile, or a styrene-based monomer (a) and a different type from the above (a) Three kinds of a monomer (b)′ selected from the group of styrene-based monomers, (meth)acrylic acid, maleic anhydride, and acrylonitrile, and a (meth)acrylic acid ester monomer (c). The former copolymer is preferable from the viewpoint of improving the Vicat softening point of the heat-resistant polystyrene resin (B). Among them, a binary copolymer or a ternary copolymer in which the monomer (b) or (b)' is (meth)acrylic acid is preferable.

The copolymerization composition ratio of the binary copolymer is (a) 80 to 99% by mass and (b) 1 to 20% by mass when the total amount of the monomers (a) and (b) is 100% by mass. Is preferred.
The copolymerization composition ratio of the ternary copolymer is (a) 60 to 98 mass %, (b) when the total amount of the monomers (a), (b)′ and (c) is 100 mass %. '1 to 20 mass% and (c) 1 to 20 mass% are preferable.

In the case of a binary copolymer, the copolymerization composition ratio of the styrene-based monomer (a) is more preferably 85 to 98% by mass, further preferably 86 to 97% by mass, and most preferably 90 to 97% by mass. ..
In the case of a terpolymer, 67 to 96 mass% is more preferable, 74 to 94 mass% is further preferable, and 78 to 92 mass% is most preferable.

  When the copolymerization composition ratio of the styrene-based monomer (a) is 80% by mass or more in the case of a binary copolymer and 60% by mass or more in the case of a terpolymer, the impact-resistant polystyrene-based resin (A) It is preferable in terms of compatibility with. When the copolymerization composition ratio of the styrene-based monomer (a) is 99% by mass or less in the case of a binary copolymer and 98% by mass or less in the case of a terpolymer, the heat-resistant polystyrene-based resin (B) It is easy to improve the Vicat softening point.

  In the case where the heat-resistant polystyrene-based resin (B) is a binary copolymer, a styrene-based monomer of a type different from that of (a), acrylonitrile, (meth)acrylic acid, (meth)acrylic acid ester, maleic anhydride is used. The copolymerization composition ratio of one kind of monomer (b) selected from the group is preferably 2 to 15% by mass, more preferably 3 to 14% by mass, and further preferably 3 to 10% by mass. In the case of a terpolymer, a copolymer of one kind of monomer (b)′ selected from the group consisting of a styrene-based monomer different from the above (a), acrylonitrile, (meth)acrylic acid, and maleic anhydride. The polymerization composition ratio is preferably 2 to 18% by mass, more preferably 3 to 16% by mass, and further preferably 4 to 14% by mass.

  When the content of the monomers (b) and (b)' is 1% by mass or more, it is easy to improve the Vicat softening point of the heat-resistant polystyrene resin (B). Further, when the content of the monomers (b) and (b)' is 20% by mass or less, the increase of the gelled product in the impact-resistant polystyrene-based resin sheet is suppressed, and the appearance becomes good. Further, the mechanical strength of the sheet is unlikely to decrease.

When the heat-resistant polystyrene resin (B) is a terpolymer, the content of the (meth)acrylic acid ester monomer (c) is preferably 2 to 15% by mass, and 3 to 10% by mass. Is more preferable, and it is further preferable that it is 4 to 8% by mass.
When the content of the (meth)acrylic acid ester monomer (c) is 20% by mass or less, water absorption of the impact-resistant polystyrene-based resin sheet is suppressed, and foaming or the like hardly occurs during sheet molding.

When the heat-resistant polystyrene-based resin (B) is a copolymer containing a (meth)acrylic acid monomer, a material constituting a sheet for suppressing gelation reaction due to dehydration reaction of (meth)acrylic acid It is preferable to contain an aliphatic primary alcohol having 14 or more carbon atoms therein. Of these, isoform aliphatic primary alcohols having a freezing point of −10° C. or lower are particularly preferable.
The content of the aliphatic primary alcohol in the material constituting the sheet of the present invention is preferably 0.02 to 1.0% by mass based on 100% by mass of the entire material.

  Examples of the aliphatic primary alcohol having 14 or more carbon atoms include n-myristyl alcohol, n-palmityl alcohol, n-stearyl alcohol and the like. Further, as the isotype aliphatic primary alcohol having a freezing point of -10°C or less, isotetradecanol having 14 carbon atoms, isohexadecanol having 16 carbon atoms, isooctadecanol having 18 carbon atoms, and carbon Examples include isoeicosanol having a number of 20, and among them, isooctadecanol having a carbon number of 18 is preferable.

  Specifically, for example, 7-methyl-2-(3-methylbutyl)-1-octanol, 5-methyl-2-(1-methylbutyl)-1-octanol, 5-methyl-2-(3-methylbutyl) -1-octanol, 2-hexyl-1-decanol, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol, 8-methyl-2-(4-methylhexyl) Examples include -1-decanol, 2-heptyl-1-undecanol, 2-heptyl-4-methyl-1-decanol, and 2-(1,5-dimethylhexyl)-(5,9-dimethyl)-1-decanol. ..

Further, in the present invention, it is preferable that the heat-resistant polystyrene-based resin (B) has a melt flow rate (MFR) of 1.5 g/10 min or more at a measurement temperature of 200° C. and a measurement load of 5 kgf. It is preferably 1.7 g/10 min or more, more preferably 1.9 g/10 min or more. The upper limit of the MFR of the heat-resistant polystyrene resin (B) is not particularly limited, but is generally 30 g/10 min or less.
When the MFR of the heat-resistant polystyrene-based resin (B) is 1.5 g/10 min or more, when mixed with the impact-resistant polystyrene-based resin (A), the domain size is likely to be small, and a sheet having good mechanical strength is obtained. It is preferable because it can be obtained.

(About the relationship between MFR(B) and MFR(A))
Below, the examination and the derivation|leading-out regarding the MFR of both impact-resistant polystyrene type resin (A) and heat resistant polystyrene type resin (B) which comprise the sheet|seat of this invention are described.
Generally, the heat-resistant polystyrene-based resin having a Vicat softening point of 106° C. or higher is incompatible with the impact-resistant polystyrene-based resin such as HIPS, so that the composition ratio of the impact-resistant polystyrene-based resin and the heat-resistant polystyrene-based resin is 50 to 50%. 99% by mass: In the case of 50 to 1% by mass, when a heat-resistant polystyrene-based resin having a Vicat softening point of 106° C. or higher is simply mixed into the impact-resistant polystyrene-based resin to form a sheet, the impact-resistant polystyrene-based resin is used. The sea and the morphology of the sea-island structure with the heat-resistant polystyrene resin as islands (domains) are formed. Then, as the domain of the above-mentioned heat-resistant polystyrene resin becomes larger, the mechanical strength such as impact resistance and tear strength of the obtained sheet tends to decrease.

This is the main reason why the sheet made by mixing the heat-resistant polystyrene-based resin with the impact-resistant polystyrene-based resin has not been able to satisfy the required physical properties such as mechanical strength, and the heat-resistant polystyrene-based resin is recycled. That is why it could not be used for.
Conventionally, in order to solve the above problems, using a heat-resistant polystyrene-based resin exhibiting a lower Vicat softening point, where the present invention has been addressed by increasing the compatibility with impact-resistant polystyrene-based resin, the present invention is , Even when a heat-resistant polystyrene-based resin having a Vicat softening point of 106° C. or higher is used, attention is paid to suppressing the decrease in the mechanical strength of the sheet by making the above-mentioned domain size smaller. The inventors found that the relationship between the melt flow rate (MFR) of both the impact resistant polystyrene resin (A) and the heat resistant polystyrene resin (B) is the controlling factor.

That is, when the melt flow rate MFR(B) of the heat-resistant polystyrene-based resin (B) and the melt flow rate MFR(A) of the impact-resistant polystyrene-based resin (A) satisfy the above formula (1), The melt viscosity of the heat-resistant polystyrene-based resin (B) in the sea (matrix) of the impact-resistant polystyrene-based resin (A) tends to be relatively small.
Therefore, the self-aggregating force of the heat-resistant polystyrene resin (B) becomes small, the islands of the sea-island structure are likely to form a structure close to uniform dispersion, and the domain size becomes small.

  In the above morphological structure in which the impact-resistant polystyrene-based resin (A) phase is the sea and the heat-resistant polystyrene-based resin (B) phase is the island (domain), the domain size exhibiting good sheet mechanical strength is not particularly limited, but In the stretched sheet, for example, the minor axis of the domain is 1.0 μm or less, and in the stretched sheet, the domain size in the thickness direction of the sheet is 1.0 μm or less.

(Resin composition)
The sheet of the present invention is an impact-resistant polystyrene-based resin sheet containing a resin composition of an impact-resistant polystyrene-based resin (A) and a heat-resistant polystyrene-based resin (B) as a main component, which is an impact-resistant polystyrene-based resin. When the total amount of (A) and the heat-resistant polystyrene resin (B) is 100% by mass, the composition ratio of both resins is (A)/(B)=50 to 99% by mass/50 to 1% by mass. Preferably, (A)/(B)=53 to 95% by mass/47 to 5% by mass, more preferably 56 to 90% by mass/44 to 10% by mass, and further preferably 59 to 85% by mass. /41 to 15% by mass. When the mass ratio of the heat-resistant polystyrene-based resin (B) is 1% by mass or more, mechanical strength such as tensile elastic modulus and tensile yield strength of the sheet can be improved. Further, when the composition ratio of the heat-resistant polystyrene-based resin (B) is 50% by mass or less, the impact resistance of the obtained impact-resistant polystyrene-based resin sheet can be imparted.

(General-purpose polystyrene resin)
The material constituting the sheet of the present invention may contain a general-purpose polystyrene resin (GPPS) in addition to the resin composition comprising the resin (A) and the resin (B) described above. As a form in which GPPS is contained, for example, it may be contained in impact-resistant polystyrene-based resin or heat-resistant polystyrene-based resin, or may be contained in impact-resistant polystyrene-based resin sheet or heat-resistant polystyrene-based resin sheet. Examples thereof include a case where they are recycled and used as a constituent material of the sheet of the present invention, a case where a general-purpose polystyrene resin sheet is recycled and used as a constituent material of a sheet of the present invention, a case where GPPS virgin pellets are mixed, and the like.

  Examples of GPPS include aromatic styrenes such as styrene, o-, m-, p-methylstyrene, p-ethylstyrene, and pt-butylstyrene, and α-alkylstyrenes such as α-methylstyrene and ethylstyrene. Examples thereof include homopolymers of group vinyl compounds, copolymers obtained by combining these monomers, and the like, and those having a Vicat softening point of less than 106°C. These GPPSs can be used alone or in combination of two or more. A preferred GPPS is homopolystyrene having a weight average molecular weight of 180,000 to 350,000.

The content of GPPS is preferably 0 to 40 mass% with respect to 100 mass% of the material constituting the sheet of the present invention. From the viewpoint of obtaining a sheet having good impact resistance, 0 to 20 mass% is more preferable.
The content of GPPS in the material constituting the sheet is determined by dissolving the sheet of the present invention, which has been weighed in advance, in chloroform, separating the solution and the insoluble matter, and then drying the chloroform of the solution to obtain GPPS and heat-resistant polystyrene. The content of the mixture of GPPS and the heat-resistant polystyrene resin (B) in the material forming the sheet can be calculated by collecting the mixture of the resin (B) and calculating the weight (operation 1). Then, by high performance liquid chromatography (HPLC), TSKgel ODS-100V (manufactured by Tosoh Corporation) for the column, evaporative light scattering detector for the detector, measurement temperature 40° C., solvent using acetonitrile/THF solvent for the mobile phase. The recovered mixture of GPPS and the heat-resistant polystyrene-based resin (B) was measured by a gradient HPLC method, and from the GPPS peak obtained by the difference in peak top retention times, the GPPS and the heat-resistant polystyrene-based resin (B) in the mixture were measured. The GPPS content can be calculated (operation 2). The content of GPPS in the material constituting the sheet can be calculated from the results of operations 1 and 2.

(Other ingredients)
The sheet of the present invention may contain inorganic particles, additives, and other resins as long as the effects of the present invention are not impaired.

For example, the blocking of the sheet can be suppressed by containing the inorganic particles. The content of the inorganic particles in the material constituting the sheet is preferably 50 to 500 ppm from the viewpoint of exhibiting appropriate irregularities on the surface of the sheet of the present invention and the viewpoint of maintaining transparency. The average particle size of the inorganic particles is preferably 1 to 20 μm.
The type of inorganic particles is not particularly limited, and examples thereof include silica, glass beads and the like, and those whose surface is chemically treated. Spherical silica containing silicon oxide as a main component is preferable because it does not modify the composition and the coating property of the silicone oil on the sheet is good.

  Further, in the sheet of the present invention, an internal lubricant, a plasticizer, a compatibilizer, a processing aid, a melt viscosity improver, an antioxidant, an antioxidant, a heat stabilizer, a light stabilizer, depending on the purpose of use. , Weather resistance stabilizer, UV absorber, neutralizing agent, nucleating agent, crosslinking agent, lubricant, anti-blocking agent, slip agent, antifogging agent, antibacterial agent, deodorant, flame retardant, antistatic agent, colorant The sheet may be manufactured by appropriately adding additives such as and pigments to the constituent materials of the sheet.

  Examples of the internal lubricant include mineral oil and the like, and the compounding amount is preferably 2.0% by mass or less based on 100% by mass of the material constituting the sheet. If blended in excess of 2.0% by mass, part of the internal lubricant volatilizes during extrusion melting, the volatilized internal lubricant adheres to the manufacturing equipment, and the agglomerated internal lubricant transfers to the sheet, resulting in the appearance of the sheet. May damage. Therefore, the blending amount of the internal lubricant is more preferably 1.0% by mass or less, further preferably 0.5% by mass or less.

  Other than the impact-resistant polystyrene-based resin (A), heat-resistant polystyrene-based resin (B), and general-purpose polystyrene resin, polyolefin-based resin, polyvinyl chloride-based resin, polyvinylidene chloride-based resin, chlorinated polyethylene-based resin Resin, polyester resin, polycarbonate resin, polyamide resin, polyacetal resin, acrylic resin, ethylene vinyl acetate copolymer, polymethylpentene resin, polyvinyl alcohol resin, cyclic olefin resin, polylactic acid resin, Polybutylene succinate resin, polyacrylonitrile resin, polyethylene oxide resin, cellulose resin, polyimide resin, polyurethane resin, polyphenylene sulfide resin, polyphenylene ether resin, polyvinyl acetal resin, polybutadiene resin, polybutene resin Resin, polyamideimide resin, polyamide bismaleimide resin, polyarylate resin, polyetherimide resin, polyetheretherketone resin, polyetherketone resin, polyethersulfone resin, polyketone resin, polysulfone resin , Aramid resins, fluorine resins and the like. The content of the other resin described above is preferably 10% by mass or less based on 100% by mass of the material forming the sheet.

Further, the sheet of the present invention may have a coating layer of an antifogging agent, an antistatic agent, a release agent such as silicone oil, etc. on the surface of the sheet. The coating amount is not particularly limited, but in order to exert the above-mentioned sheet performance, it is preferable to coat at least one surface in the range of 5 to 100 mg/m ² . As the release agent, silicone oil is preferable, and polydimethylsiloxane is more preferable because it does not easily attack the surface of the sheet during high temperature molding.

When the secondary molded article of the sheet of the present invention is used as a food packaging material, a coating layer containing a release agent is arranged on one surface, and a coating layer containing an antifogging agent is arranged on the other surface to prevent It is advisable to use the clouding agent layer side facing the food content side. The coating amount of the antifogging agent is not particularly limited, but from the viewpoint of antifogging performance, it is preferable to apply the antifogging agent in the range of 10 to 100 mg/m ^{2 on} at least one side. As the antifogging agent, a known surfactant can be used, and particularly, polyhydric alcohol fatty acid ester such as sucrose fatty acid ester and polyglycerin fatty acid ester are preferable, and polyvinyl alcohol, polyoxyethylene polyoxypropylene block copolymer, etc. A mixture of two or more kinds of a polyhydric alcohol fatty acid ester and a water-soluble polymer, a polysaccharide such as methyl cellulose or cyclodextrin, or the like is particularly preferable.

<Method for producing impact-resistant polystyrene-based resin sheet>
The method for producing the sheet of the present invention is not particularly limited and can be produced by a conventionally known method. For example, it can be obtained by melting a constituent material of a sheet containing the resin composition as a main component using an extruder, extruding it into a sheet form from a die, and cooling and solidifying with a cooling roll, air cooling, or water cooling. Further, a method of obtaining the sheet by stretching the sheet obtained by the above-mentioned method in at least one direction and then winding the sheet with a winding machine can be exemplified. Here, the “sheet” has the meaning of including a thick sheet to a thin film.

  Specifically, as a method for obtaining a sheet, after mixing the materials constituting the sheet of the present invention, an extruder such as a single-screw extruder, a different-direction twin-screw extruder, a same-direction twin-screw extruder is used, Facilitates uniform distribution of material. When the material constituting the sheet of the present invention is composed of a plurality of types, it may be mixed in a mixer such as a tumbler mixer, a mixing roll, a Banbury mixer, a ribbon blender, or a super mixer, and then charged into an extruder, or the like. It is also possible to connect a strand die to the tip of the kneading machine, and once pelletize by a method such as strand cutting or die cutting, the pellets obtained may be put into an extruder. Further, once pelletized, other components may be put into the extruder together with the obtained pellets.

The resin composition melted by the extruder is connected to a die such as a T die at the tip of the extruder, molded into a sheet, and then cooled and solidified by a cooling roll.
The extrusion temperature is preferably about 180 to 260°C, more preferably 190 to 250°C. By optimizing the extrusion temperature and the state of shearing, it is effective to bring various physical properties and mechanical properties to desired values.

The stretching method of the sheet of the present invention is not particularly limited, but roll stretching in the sheet flow direction (hereinafter, may be referred to as machine direction or MD) or a direction perpendicular to the sheet flow direction ( Hereinafter, it is preferably biaxially stretched by a tenter stretching or the like in the transverse direction or TD).
Further, as described above, it may be stretched in the longitudinal direction and then in the transverse direction, or may be stretched in the transverse direction and then in the longitudinal direction. Further, as long as it is stretched in the machine direction and the transverse direction, it may be stretched twice or more in the same direction. Furthermore, it may be stretched in the machine direction, then in the transverse direction, and further in the machine direction. Further, it may be simultaneously stretched in the machine direction and the transverse direction by a simultaneous biaxial stretching machine. Further, the unstretched sheet may be cut and biaxially stretched by a batch type stretching machine.

  As the stretching in the longitudinal direction, a longitudinal stretching method using a roll is preferable. The longitudinal stretching method using a roll is a method in which a low-speed roll and a high-speed roll are rotated in the same direction to pass a sheet in parallel, and a method of stretching and a method in which a low-speed roll and a high-speed roll are reversely rotated to lay the sheet on the side There is a method of passing the paper through and stretching it, and any combination of one-step or multi-step, parallel hanging or side hanging can be used. It is also possible to install a heater or the like between the low speed roll and the high speed roll, and perform stretching while heating with the heater. Stretching in the transverse direction is preferably tenter stretching.

  The stretching ratio in longitudinal stretching and transverse stretching differs depending on the resin composition constituting the impact-resistant polystyrene-based resin sheet, but is usually 1.5 to 15 times, and more preferably 4 to 10 times in terms of areal magnification. In the case of sequential stretching, the stretching ratio in the machine direction is 1.2 to 5 times, preferably 1.5 to 3.0 times, and the stretching ratio in the transverse direction is 1.2 to 5 times, preferably 1. It is 5 to 3.0 times. The draw ratio in each direction of the simultaneous biaxial stretching is preferably 1.5 to 5 times.

  The stretching temperature in the longitudinal stretching and the transverse stretching differs depending on the resin composition constituting the impact-resistant polystyrene-based resin sheet, but both the longitudinal stretching and the transverse stretching may be performed at a temperature of about 110°C to 170°C. preferable.

  Antifogging agent, antistatic agent, a coating layer such as a release agent is extruded in a sheet form from a die, cooled and solidified by cooling rolls, air cooling, water cooling, or after stretching the sheet, on the sheet surface by a known method. It can be formed by coating. Further, before forming the coating layer, the sheet surface can be subjected to corona treatment by a known method.

  The thickness of the impact-resistant polystyrene-based resin sheet of the present invention is not particularly limited, but is preferably 0.08 to 1 mm from the viewpoint of sheet strength, heat resistance, moldability, economic efficiency, etc., and 0.1 to 0. 0.7 mm is more preferable. The sheet of the present invention may be laminated with thermoplastic resins of the same kind or different kinds by coextrusion or dry lamination, if necessary.

  When the impact-resistant polystyrene-based resin sheet of the present invention is stretched, the impact-resistant polystyrene-based resin sheet is measured under the temperature condition of Vicat softening point +30°C according to ASTM D-2838-02. The orientation relaxation stress is preferably 0.2 to 2.0 MPa, more preferably 0.4 to 1.0 MPa. If the orientation relaxation stress is 0.2 MPa or more, the impact resistance of the sheet increases and the folding endurance tends to be good, and if it is 2.0 MPa or less, stretch breakage of the sheet does not easily occur, and the secondary formability is improved. It tends to be good. The orientation relaxation stress can be set within the above-mentioned preferable range by appropriately adjusting the stretching ratio and the stretching temperature.

The mechanical strength of the sheet of the present invention is preferably as good as the case where a general-purpose polystyrene resin is mixed with a high-impact polystyrene resin at a composition ratio of 50 to 99% by mass/50 to 1% by mass, Most preferably, it is about the same as a sheet composed only of high impact polystyrene resin.
For example, in the case of an unstretched sheet, the tensile yield strength is preferably 29 MPa or higher, more preferably 31 MPa or higher. The tensile elongation at break is preferably 25% or more, more preferably 30% or more. The tear strength is preferably 1.5 N/mm or more, more preferably 2.0 N/mm or more. The surface impact strength (maximum impact point energy) is preferably 0.5 J or more, more preferably 0.7 J or more.

<Molded products>
The use of the sheet of the present invention is not particularly limited, but from the viewpoint of excellent heat resistance, impact resistance, folding resistance, etc. of the molded product, the impact-resistant polystyrene-based resin sheet of the present invention is hot plate compressed air. By vacuum forming (direct heating method), pressure forming method, or vacuum pressure forming method (indirect heating method), secondary molding into a desired container shape can be suitably used as a molded product such as a food packaging material. For example, it can be suitably used as a container such as a box-shaped container main body for storing foods such as fresh food, dried food, and confectionery, a container with a lid, a cup, a tray, a lidless container such as a plate, and a lid.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, each measurement and evaluation were performed as follows.

(1) Tensile Yield Strength, Tensile Rupture Elongation Based on JISK7127 (1999), 5 sheets each of MD and TD of the sheets obtained in Examples, Comparative Examples and Reference Examples are dumbbell-shaped. Punch a test piece (test piece type 5, narrow parallel part width 6 mm) with a cutting blade, draw a marked line (marker distance 25 mm) on the narrow parallel part, initial distance between chucks 80 mm, measurement atmosphere temperature 23°C, test The tensile test was performed 5 times each at a speed of 200 mm/min, the average value of the tensile yield strength and the tensile elongation at break were calculated, and the average value was used as the measured value. In this measurement, the tensile yield strength was the maximum strength in all measurements.

(2) Tear strength In order to measure the MD tear strength of the sheets obtained in Examples, Comparative Examples and Reference Examples, in accordance with JIS K7128-1 (1998), test pieces of MD 150 mm and TD 50 mm were cut into 5 pieces each. A trouser-type test piece was produced by punching with a blade and forming a slit having a length of 75 mm with respect to MD in the center of the test piece TD. Further, in order to measure the tear strength of the TD of the sheet, in accordance with JIS K7128-1 (1998), five test pieces of TD150 mm and MD50 mm are punched out with a cutting blade, and five pieces of the test piece MD are punched with respect to TD. A trouser-type test piece was prepared by inserting a slit having a length of 75 mm. After that, the long legs of the test piece were attached to a tensile tester, and the tensile test was performed 5 times each at a measurement atmosphere temperature of 23° C. and a test speed of 200 mm/min, and the average tear strength of MD and TD of each sheet was measured. The value was calculated and the average value was used as the measured value.

(3) Surface impact strength (maximum impact point energy)
Based on JISK712-2 (1999), a test piece of a predetermined size was punched with a cutting blade from the sheets obtained in Examples, Comparative Examples and Reference Examples, and five sheets were produced for each sheet. For each of these 5 test pieces, an impact test was performed 5 times under the conditions of a measurement atmosphere temperature of 23° C. and an atmosphere temperature of 2 conditions of 0° C. and an impact velocity of 3.0 m/sec. The average value of the maximum impact point energy was calculated, and the average value was used as the measured value.

The raw materials used in each Example, Comparative Example and Reference Example are as follows.
The melt flow rate (MFR) of the raw material resin used is a value measured at a measurement temperature of 200° C. and a measurement load of 5 kgf.

<Impact-resistant polystyrene resin (A)>
A-1: high impact polystyrene (graft type HIPS, graft monomer: styrene, rubber component composition: polybutadiene rubber, diene content in rubber component; 7.5 mass %, average particle diameter of rubber particles: 4.0 μm , MFR=2.5g/10min)

<Heat resistant polystyrene resin (B)>
B-1: Styrene-methacrylic acid copolymer (97% by mass of styrene monomer, 3% by mass of methacrylic acid monomer, MFR=2.8 g/10 min, Vicat softening point 107° C.)
B-2: Styrene-methacrylic acid copolymer (97% by mass of styrene monomer, 3% by mass of methacrylic acid monomer, MFR=2.0 g/10 min, Vicat softening point 108° C.)
B-3: Styrene-methacrylic acid copolymer (95% by mass of styrene monomer, 5% by mass of methacrylic acid monomer, MFR=1.8 g/10 min, Vicat softening point 110° C.)

<Other heat-resistant polystyrene resins>
C-1: Styrene-methacrylic acid copolymer (95% by mass of styrene monomer, 5% by mass of methacrylic acid monomer, MFR=1.0 g/10 min, Vicat softening point 110° C.)

<General-purpose polystyrene resin>
D-1: Homopolystyrene resin (100% by mass of styrene monomer, MFR=3.3 g/10 min, Vicat softening point 100° C.)

<Reference example 1>
After the impact-resistant polystyrene-based resin (A-1) 80% by mass and the general-purpose polystyrene-based resin (D-1) 20% by mass were mixed and put into a single-screw extruder, and melt-kneaded at a set temperature of 230°C, A sheet having a thickness of 250 μm was obtained by extruding with a T-die connected to the tip of a single-screw extruder, pulling with a casting roll set at 100° C., and cooling and solidifying.

<Reference example 2>
A sheet was prepared in the same manner as in Reference Example 1 except that 60% by mass of the impact-resistant polystyrene-based resin (A-1) and 40% by mass of the general-purpose polystyrene-based resin (D-1) were mixed and charged into a single-screw extruder. Obtained.

<Reference example 3>
A sheet was obtained in the same manner as in Reference Example 1, except that 100% by mass of the impact-resistant polystyrene-based resin (A-1) was charged into the single-screw extruder.

<Example 1>
A sheet was prepared in the same manner as in Reference Example 1 except that 80% by mass of the impact-resistant polystyrene-based resin (A-1) and 20% by mass of the heat-resistant polystyrene-based resin (B-1) were mixed and charged into a single-screw extruder. Obtained.

<Example 2>
A sheet was prepared in the same manner as in Reference Example 1 except that 60% by mass of the impact-resistant polystyrene-based resin (A-1) and 40% by mass of the heat-resistant polystyrene-based resin (B-1) were mixed and charged into a single-screw extruder. Obtained.

<Example 3>
A sheet was prepared in the same manner as in Reference Example 1 except that 80% by mass of the impact-resistant polystyrene-based resin (A-1) and 20% by mass of the heat-resistant polystyrene-based resin (B-2) were mixed and charged into a single-screw extruder. Obtained.

<Example 4>
A sheet was prepared in the same manner as in Reference Example 1 except that 60% by mass of the impact-resistant polystyrene-based resin (A-1) and 40% by mass of the heat-resistant polystyrene-based resin (B-2) were mixed and charged into a single-screw extruder. Obtained.

<Example 5>
A sheet was prepared in the same manner as in Reference Example 1 except that 80% by mass of the impact-resistant polystyrene-based resin (A-1) and 20% by mass of the heat-resistant polystyrene-based resin (B-3) were mixed and charged into a single-screw extruder. Obtained.

<Example 6>
A sheet was prepared in the same manner as in Reference Example 1 except that 60% by mass of the impact-resistant polystyrene-based resin (A-1) and 40% by mass of the heat-resistant polystyrene-based resin (B-3) were mixed and charged into a single-screw extruder. Obtained.

<Comparative Example 1>
A sheet was prepared in the same manner as in Reference Example 1 except that 80% by mass of the impact-resistant polystyrene-based resin (A-1) and 20% by mass of the heat-resistant polystyrene-based resin (C-1) were mixed and charged into a single-screw extruder. Obtained.

<Comparative example 2>
A sheet was prepared in the same manner as in Reference Example 1 except that 60% by mass of the impact-resistant polystyrene-based resin (A-1) and 40% by mass of the heat-resistant polystyrene-based resin (C-1) were mixed and charged into a single-screw extruder. Obtained.

The above-mentioned measurements and evaluations were performed on the sheets obtained in Reference Examples, Examples and Comparative Examples, and summarized in Table 1.
Further, the sheet mechanical strength when the impact-resistant polystyrene-based resin (A) is mixed with the heat-resistant polystyrene-based resin, as compared with the sheet mechanical strength when the general-purpose polystyrene resin is mixed with the impact-resistant polystyrene-based resin (A). In order to evaluate, the ratio of each measured value of Example 1, Example 3, Example 5, and Comparative Example 1 having the same (A-1) mixing ratio of 80% by mass to that of Reference Example 1 with respect to the measured value of Reference Example 1. (%), and the measurement values of Example 2, Example 4, Example 6, and Comparative Example 2 having the same (A-1) mixing ratio of 60 mass% as those of Reference Example 2 are the measurement values of Reference Example 2. It was expressed as a ratio (%) to Table 2 and is summarized in Table 2.

As shown in Table 1, the sheets obtained in Examples 1 to 6 have a tensile elongation at break of 25% or more in MD and TD, a tear strength of 1.5 N/mm or more in both MD and TD, and maximum impact. The point energy shows 0.5 J or more at both measurement temperatures of 23° C. and 0° C., and it is understood that in both cases, the mechanical strength is sufficient for use as a high impact polystyrene resin sheet.
In addition, as shown in Table 2, the sheets obtained in Examples 1 to 6 were compared with Reference Examples 1 and 2 in which a general-purpose polystyrene resin was used instead of the heat-resistant polystyrene resin (B), respectively. Since the physical property value does not become 50% or less (the evaluation value in the reference example), it can be seen that the remarkable decrease in the mechanical property value is suppressed. Further, it can be seen that, depending on the evaluation items, a good sheet of 100% or more (evaluation value in the reference example) was obtained.

  On the other hand, the sheets of Comparative Examples 1 and 2 using the heat-resistant polystyrene-based resin (C-1) deviating from the formula (1) defined by the present invention are TD tensile rupture elongation, MD tear strength, and maximum impact point. A significant decrease in energy was confirmed. Even when compared with Examples 5 and 6 using the heat-resistant polystyrene resin (B-3) having the same Vicat softening point, it is clear that the degree of deterioration of various mechanical properties is remarkable.

  That is, the mass ratio of the mixed resin composition of the impact-resistant polystyrene-based resin (A) and the heat-resistant polystyrene-based resin (B), the melt flow rate of the impact-resistant polystyrene-based resin (A) and the heat-resistant polystyrene-based resin (B), It can be seen that by setting the relationship and the Vicat softening point of the heat-resistant polystyrene-based resin (B) within the range defined by the present invention, an impact-resistant polystyrene-based resin sheet having excellent impact resistance and tear strength can be obtained.

  Although the present invention has been described above with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. Without being subject to the gist of the invention or the concept that can be read from the claims and the entire specification, the impact-resistant polystyrene-based resin sheet accompanied by such changes, and a molded article made of the sheet can be appropriately modified. Should also be understood as being included in the technical scope of the present invention.

  The impact-resistant polystyrene-based resin sheet of the present disclosure is an impact-resistant polystyrene-based resin sheet having excellent physical properties such as impact resistance and tear strength even when a heat-resistant polystyrene-based resin is mixed with the impact-resistant polystyrene-based resin. Therefore, for example, the skeleton of the heat-resistant polystyrene-based resin sheet can be mixed with the impact-resistant polystyrene resin to form a sheet, which can be reused, which is very useful for industrial resources.

Claims (6)

An impact-resistant polystyrene-based resin sheet comprising, as a main component, a resin composition of impact-resistant polystyrene-based resin (A) and heat-resistant polystyrene-based resin (B), which satisfies the following (i) to (iii): Characteristic high impact polystyrene resin sheet.
(I) The composition ratio (A)/(B) is 50 to 99% by mass/50 when the total amount of the impact-resistant polystyrene-based resin (A) and the heat-resistant polystyrene-based resin (B) is 100% by mass. ~ 1% by weight,
(Ii) the heat-resistant polystyrene resin (B) has a Vicat softening point of 106° C. or higher,
(Iii) The melt flow rate MFR(A) of the high impact polystyrene resin (A) and the melt flow rate MFR(B) of the heat resistant polystyrene resin (B) satisfy the equation (1).
MFR(B)−MFR(A)≧−1.0 [unit: g/10 min]...Equation (1)   The impact-resistant polystyrene-based resin sheet according to claim 1, wherein the MFR (B) is 1.5 g/10 min or more.   The heat-resistant polystyrene-based resin (B) includes a styrene-based monomer (a), a styrene-based monomer of a different type from the (a), (meth)acrylic acid, a (meth)acrylic acid ester, and maleic anhydride. And a binary copolymer with one kind of monomer (b) selected from the group of acrylonitrile, or a styrene-based monomer (a), and a styrene-based monomer of a type different from the above (a) A terpolymer of one monomer (b)′ selected from the group consisting of, (meth)acrylic acid, maleic anhydride, and acrylonitrile, and a (meth)acrylic acid ester monomer (c). The impact-resistant polystyrene-based resin sheet according to claim 1 or 2, characterized in that it is present.   When the composition ratio of the binary copolymer is 100% by mass when the total of the monomer (a) and the monomer (b) is 100% by mass, (a) is 80 to 99% by mass, (b). Is 1 to 20% by mass, the impact-resistant polystyrene-based resin sheet according to claim 3.   When the composition ratio of the ternary copolymer is 100% by mass when the total of the monomer (a), the monomer (b)′ and the monomer (c) is 100% by mass, 60-98 mass %, (b)' is 1-20 mass %, (c) is 1-20 mass %, The impact-resistant polystyrene type resin sheet of Claim 3 characterized by the above-mentioned.   A molded article comprising the impact-resistant polystyrene-based resin sheet according to claim 1.