JP5573321B2 - Polystyrene resin coating resin composition and coated molded article - Google Patents

Description

  The present invention relates to a resin composition for coating a polystyrene-based resin and a coated molded article, and particularly has excellent adhesion to a polystyrene resin (PS resin), and a resin composition for coating a coated molded article by co-extrusion with PS resin or two-color molding. A resin composition for coating a polystyrene resin suitable as a product, and a coated molded product obtained by forming a coating layer on a PS resin substrate by coextrusion or two-color molding using the resin composition for coating a polystyrene resin About.

  Conventionally, a composite construction material having a laminated structure in which a plurality of materials are co-extruded or a plurality of molded sheets or plates are bonded is generally based on a vinyl chloride resin or a material in which a vinyl chloride resin is filled with a filler. As the surface layer material, a resin of the same type as the vinyl chloride resin, or a resin having high adhesion to the vinyl chloride resin, such as an ABS resin or an acrylic resin, is used even if it is a different type of resin. I came.

  However, the ABS resin is excellent in processability and appearance, but the cost is higher than that of the PS resin, and the use of the ABS resin for the entire product has a drawback of increasing the product cost.

  Under these circumstances, the base resin (non-design side) is made of an inexpensive PS resin material that has excellent foam moldability and the like, and the surface layer material (design side) is made of highly functional ABS resin. The composite material which has been provided is provided (for example, patent document 1).

  In addition, some building materials and exterior members are required to have a non-glossy molded product surface for the purpose of design and high-class feeling. As a conventional matting method for a resin molded product, for example, a method of adding chlorinated polyethylene, bismuth trioxide, and tricresyl phosphate to a resin (Patent Document 2), a heavy polymer containing an unsaturated carboxylic acid ester unit is used. A method of blending a blend (Patent Document 3), a method of blending an epoxy group-containing olefin copolymer (Patent Documents 4 and 5), a method using a graft polymer having a low graft ratio (Patent Document 6), a vinyl cyanide monomer A method for making a difference in the amount of the monomer (Patent Document 7) can be mentioned.

JP-A-63-115739 Japanese Patent Publication No. 49-44582 JP-A-56-133353 JP 59-89346 A JP 60-18536 A Japanese Patent Publication No. 62-59725 JP-A-2005-76015

However, in the ABS resin / PS resin composite molded product by ordinary coextrusion molding,
(1) A product may be missing (hereinafter referred to as “chipping”) due to cutting during production.
(2) In the manufacturing process, delamination is likely to occur due to insufficient adhesion between the base material layer and the surface layer.
(3) (1) and (2) lead to generation of defective products, resulting in a decrease in manufacturing yield and waste of resources and energy.
(4) Even during use of the product, delamination between the base material layer and the surface layer occurs, causing the product to greatly impair the durability of the product.
There was a problem.
Furthermore, in the above-described conventional technology, it has been impossible to impart sufficient matting properties to the surface of the coated molded product.

  The present invention has been made in view of the above-described conventional situation, and as a surface layer material, in addition to excellent adhesion to a PS resin as a base resin and its waste resin, processability (for example, chipping resistance), A resin composition for coating a polystyrene resin that can provide a coated molded article that is excellent in durability (for example, heat cycle resistance) and also has a matte property, and the resin composition for coating a polystyrene resin It is an object to provide a coated molded product as a material.

  As a result of intensive studies to solve the above problems, the present inventors have found that the vinyl cyanide monomer content of the vinyl monomer mixture used for the graft copolymer in the ABS resin, and further the vinyl copolymer It has been found that the above-mentioned problems can be solved by controlling the vinyl cyanide monomer content of the vinyl monomer mixture used in the above to a predetermined range.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[ 1 ] A resin composition for forming a coating layer on a base material made of a polystyrene resin, and a vinyl containing at least an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer. A vinyl copolymer (A) obtained by copolymerizing a graft copolymer (A) obtained by polymerizing a monomer mixture and a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer. B), and the content of the vinyl cyanide monomer in the vinyl monomer mixture used in the graft copolymer (A) is 5 to 20% by mass, and the vinyl copolymer ( A resin composition for coating a polystyrene resin, wherein the vinyl cyanide monomer content in the vinyl monomer mixture used in B) is 5 to 23% by mass.

[ 2 ] A covering molding comprising a base material made of a polystyrene resin, and a coating layer formed on the base material using the polystyrene resin coating resin composition according to [1 ]. Goods.

Since the resin composition for coating a polystyrene-based resin of the present invention has good adhesion to the PS resin, the profile extrusion molding, two-color molding, blow molding, sheet molding, and vacuum molding or compressed air after sheet molding. In molding, etc., a good ABS resin / PS resin composite coated molded product can be obtained under a wide range of molding conditions without being excessively restricted by molding conditions. Furthermore, the surface of the obtained coated molded product is good. A matte finish can also be imparted.
The coated molded article of the present invention using such a resin composition for coating a polystyrene resin of the present invention is particularly suitably used for building materials and exterior members.

Hereinafter, embodiments of the present invention will be described in detail.
In the following, “(co) polymerization” means both “polymerization” and “copolymerization”.

[Resin composition for coating polystyrene resin]
The resin composition for coating a polystyrene resin of the present invention is a graft copolymer obtained by polymerizing a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer. Polystyrene-based resin coating comprising a blend (A) and a vinyl copolymer (B) obtained by copolymerizing a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer. a use resin composition, a content of the vinyl cyanide monomer accounts for vinyl monomer mixture used in the graft copolymer (a) is 5 to 20 wt%, vinyl-copolymer (B The content of the vinyl cyanide monomer in the vinyl monomer mixture used in (5) is 5 to 23% by mass.

<Graft copolymer (A)>
The graft copolymer (A) according to the present invention comprises an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer, and these vinyl monomers used as necessary. It is obtained by graft polymerization of a mixture of polymerizable vinyl monomers (hereinafter sometimes referred to as “copolymerizable vinyl monomers”).

  The rubbery polymer used here includes conjugated diene copolymers such as polybutadiene, copolymers of butadiene and vinyl monomers copolymerizable therewith, acrylate polymers, acrylic acid Acrylate ester copolymer such as a copolymer of ester and vinyl monomer copolymerizable therewith, ethylene-propylene or butene (preferably propylene) -nonconjugated diene copolymer, polyorganosiloxane Examples thereof include system (co) polymers.

  Here, polybutadiene is a generic term for those having a structure such as cis and trans, and a conjugated diene copolymer such as a copolymer of butadiene and a vinyl monomer copolymerizable therewith is SBR. (Styrene-butadiene copolymer rubber), NBR (acrylonitrile-butadiene copolymer rubber) and the like.

  In addition, acrylic acid ester polymers and acrylic acid ester copolymers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2- Examples include methylpentyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate.

  These rubbery polymers may be used alone or in a combination of two or more in any combination and ratio.

  The vinyl monomer mixture to be grafted to the rubbery polymer contains at least an aromatic vinyl monomer and a vinyl cyanide monomer, and can be copolymerized with these if necessary. Can be contained.

Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, o-, m- or p-methylstyrene, vinyl xylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene, p. -Tert-butylstyrene, ethylstyrene, vinylnaphthalene and the like. Among these, styrene and α-methylstyrene are preferable.
These aromatic vinyl monomers may be used alone or in a combination of two or more in any combination and ratio.

  Specific examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile and the like. These may be used alone or in combination of two or more in any combination and ratio. Also good.

  Specific examples of copolymerizable vinyl monomers include α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid; methyl (meth) acrylate (“(meth) acrylate” indicates “acrylate and methacrylate”) , Β-unsaturated carboxylic acid esters such as ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; maleic anhydride Α, β-unsaturated dicarboxylic anhydrides such as itaconic anhydride; α, β-unsaturated dicarboxylic acids such as maleimide, N-methylmaleimide, N-ethylmaleimide, N-phenylmaleimide, and N-o-chlorophenylmaleimide Examples thereof include imide compounds of acids, and these may be used alone or as 2 You may mix and use a seed | species or more by arbitrary combinations and a ratio.

  In the present invention, the content of the vinyl cyanide monomer in the vinyl monomer mixture used in the graft copolymer (A) is 5 to 20% by mass, more preferably 5 to 15% by mass. When the content of the vinyl cyanide monomer in the vinyl monomer mixture is within this range, good adhesion to the polystyrene resin can be obtained.

  In addition, it is preferable that the ratio which occupies for the vinyl monomer mixture of the copolymerizable vinyl monomer used as needed is 20 mass% or less, especially 15 mass% or less. When the proportion of the copolymerizable vinyl monomer used is not more than the above upper limit, the balance between the adhesion to the polystyrene resin and the mechanical properties is good.

  In addition, the content of the rubbery polymer of the graft copolymer (A) according to the present invention is 30 to 75% by mass, and particularly 40 to 70% by mass. It is preferable in obtaining the resin composition for coating a polystyrene resin of the present invention.

  Specific examples of the graft copolymer (A) according to the present invention include ABS (polybutadiene-styrene-acrylonitrile) resin, ASA (acrylic rubber-styrene-acrylonitrile) resin, AES (ethylene-propylene-nonconjugated diene rubber). -Styrene-acrylonitrile) resin, SAS (polyorganosiloxane rubber-styrene-acrylonitrile) resin.

  The graft copolymer (A) according to the present invention is produced by graft polymerization of a vinyl monomer mixture containing at least a vinyl cyanide monomer and an aromatic vinyl monomer in the presence of a rubbery polymer. Is done.

  The production method of the graft copolymer (A) is not particularly limited, but a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a bulk suspension polymerization method, or an emulsion polymerization method may be employed. it can. For example, a method of emulsion polymerization by adding a vinyl monomer mixture and a polymerization initiator in the presence of a rubbery polymer can be mentioned. Examples of the polymerization initiator used in the emulsion polymerization include redox polymerization initiators such as persulfate or cumene hydroperoxide-sodium formaldehyde sulfoxylate.

<Vinyl copolymer (B)>
The vinyl copolymer (B) according to the present invention includes an aromatic vinyl monomer, a vinyl cyanide monomer, and other copolymers copolymerizable with these vinyl monomers used as necessary. Aromatic vinyl monomer, vinyl cyanide monomer, and copolymerizable vinyl monomer used in the production of vinyl copolymer (B) Examples thereof include those exemplified as the aromatic vinyl monomer, vinyl cyanide monomer and copolymerizable vinyl monomer that can be used in the production of the aforementioned graft copolymer (A). , One type may be used alone, or two or more types may be mixed and used.

When the content of the vinyl cyanide monomer in the vinyl monomer mixture used in the vinyl copolymer (B) is in the range of 5 to 23% by mass, in addition to the adhesion to the polystyrene resin, A matte appearance can be obtained.

  There is no restriction | limiting in particular as a manufacturing method of a vinyl copolymer (B), Well-known methods, such as block polymerization method, solution polymerization method, suspension polymerization method, block suspension polymerization method, and emulsion polymerization, are mentioned.

In the present invention, the mass average molecular weight of the vinyl copolymer (B) is preferably 50,000 to 300,000 in terms of polystyrene measured using gel permeation chromatography (GPC).
If the mass average molecular weight of the vinyl copolymer (B) is within the above range, impact resistance and / or heat resistance tends to be selected, and a resin composition having a good balance of physical properties can be obtained.

<Mixing ratio of graft copolymer (A) and vinyl copolymer (B)>
In the resin composition for coating a polystyrene resin of the present invention, the contents of the graft copolymer (A) and the vinyl copolymer (B) are not particularly limited, but excellent effects are obtained with respect to surface matting and moldability. Therefore, it is preferable that these total amounts are contained in the following proportions in 100 parts by mass.
Graft copolymer (A): 20-80 parts by weight, especially 30-60 parts by weight Vinyl copolymer (B): 80-20 parts by weight, particularly 70-40 parts by weight

<Rubber polymer content>
In the polystyrene resin coating resin composition of the present invention, the content of the rubbery polymer in the polystyrene resin coating resin composition is preferably 12.5 to 30% by mass.
When the content of the rubbery polymer in the composition is less than 12.5% by mass, the matte effect is reduced and the impact resistance is also lowered. Further, if the content of the rubbery polymer exceeds 30% by mass, the moldability tends to be deteriorated.
The preferable content of the rubbery polymer in the resin composition for coating a polystyrene resin of the present invention is 13 to 29% by mass, and more preferably 15 to 28% by mass.

<Inorganic filler>
By adding an inorganic filler to the polystyrene resin coating resin composition of the present invention, it is possible to modify a molded product or improve moldability. Examples of the inorganic filler include glass fiber, glass flake, glass bead, hollow glass, carbon fiber, talc, mica, metal fiber, wollastonite, kaolin, barium sulfate, graphite, molybdenum disulfide, zinc oxide whisker, and oxidation. Magnesium, calcium carbonate, potassium titanate whisker, lock filler and the like can be mentioned. These may be used alone or in a combination of two or more in any combination and ratio.

  Of these inorganic fillers, glass fibers, glass flakes, carbon fibers, talc, metal fibers, and zinc oxide whiskers are preferable. Moreover, as a dimension of fibrous inorganic fillers, such as glass fiber and carbon fiber, what has a fiber diameter of 5-60 micrometers and a fiber length of 30 micrometers or more is preferable.

  When the resin composition for coating a polystyrene-based resin of the present invention contains an inorganic filler, the inorganic filler cannot be sufficiently obtained even if the content is too much or too little. Is preferably used in a proportion of 50 parts by mass or less, particularly 1 to 20 parts by mass with respect to 100 parts by mass in total of the graft copolymer (A) and the vinyl copolymer (B) used in the present invention.

<Other additives>
In addition to the above components, the resin composition for coating a polystyrene-based resin of the present invention is used, as necessary, at the time of production (mixing) and molding of the resin composition as long as the physical properties are not impaired. One or more usual additives such as pigments, dyes, lubricants, ultraviolet absorbers, antioxidants, antistatic agents, reinforcing agents, flame retardants and the like can be blended.

  Moreover, resin other than the said graft copolymer (A) and a vinyl copolymer (B), rubber | gum, an elastomer, etc. may be contained to such an extent that the objective of this invention is not impaired.

<Manufacturing method>
There is no particular limitation on the method for producing the resin composition for coating a polystyrene-based resin of the present invention, and the resin composition for coating a polystyrene-based resin of the present invention should be manufactured using a conventional method and apparatus. Can do. A generally used method is a melt mixing method, and examples of the apparatus used at that time include a single screw extruder, a twin screw extruder, a Banbury mixer, a roller, and a kneader. The production of the resin composition for coating a polystyrene-based resin may be carried out either batchwise or continuously, and there is no particular limitation on the mixing order of each component, and all the components are mixed sufficiently uniformly. That's fine.

[Coated molded products]
The coated molded article of the present invention is formed by forming a coating layer on a polystyrene resin substrate using the above-described resin composition for coating a polystyrene resin of the present invention.

  There is no restriction | limiting in particular as polyethylene-type resin as base resin, PS resin (polystyrene resin), HIPS resin (high impact polystyrene resin), waste PS resin, waste HIPS resin, etc. are mentioned. These can be used individually by 1 type or in mixture of 2 or more types.

  Furthermore, various additives and other resins (including waste materials thereof) are blended in the base resin to the extent that it does not affect the adhesion between the polystyrene resin coating resin composition of the present invention and the base resin. be able to. Among these various additives and other resins, as the additive, those mentioned above as other additives that can be blended in the above-mentioned inorganic filler and the resin composition for coating a polystyrene resin of the present invention. Can be mentioned. Moreover, as other resin, the following can be used.

  Rubber-reinforced styrene resins such as ABS resin, ASA resin, AES resin, vinyl chloride resin, AS resin, polycarbonate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyacetal resin, nylon resin, methacrylic resin (PMMA resin) , Polypropylene resin, polyvinyl chloride resin, polyphenylene ether resin, polylactic acid resin, polysulfone, polyether ketone, polyether sulfone, polyether sulfone, fluororesin, silicone resin, polyethylene, polyester elastomer, polycaprolactone, aromatic polyester elastomer, Polyamide-based elastomers, polyethylene waxes such as AS-grafted polyethylene and AS-grafted polypropylene, hydrogenated polybutadiene, Both such one styrene polymer block and at least one consisting of butadiene polymer block copolymers of hydrogenated products thereof. Also, a blend of two or more of these may be used, and the resin modified with a compatibilizer or functional group.

  In addition, in the reuse of the waste material, the resin exemplified as the base resin and other resin that can be blended may be a recovered product from the market or a resin discharged from various processing steps. Moreover, what is not used as a product, such as a molded product at an initial stage when molding the coated molded product of the present invention or a piece of a product, can be recovered and used as a base resin.

  Moreover, there is no restriction | limiting in particular as foaming, the presence or absence of a hollow as a shaping | molding form of a base material.

  Further, the type of foaming agent that can be used when foaming the base resin is not particularly limited, but one or two types selected from azo compounds, nitroso compounds, hydrazine derivatives, and bicarbonates. It is preferable to use a combination of the above. Moreover, as a spreading agent when mixing a foaming agent, a dietary oil, a liquid paraffin, a fatty acid, etc. can be used.

  The molding method of the coated molded product of the present invention using the resin composition for coating a polystyrene-based resin of the present invention includes profile extrusion molding, two-color molding, blow molding, sheet molding, and vacuum molding and compressed air after sheet molding. Although molding methods for processing various molten resins such as molding can be adopted, coating molding by coextrusion molding or two-color molding is preferable.

  The coextrusion molding is a method in which a coating layer made of the polystyrene resin coating resin composition of the present invention and a base resin are brought into close contact with each other using various extrusion molding methods such as extrusion molding, sheet extrusion molding, and profile extrusion molding. This is a molding method.

  Coextrusion molding can be generally performed using a known apparatus. Although there is no restriction | limiting in particular in the shaping | molding apparatus to be used, A series of apparatuses consisting of an extruder, a die, a sizing die, a cooling tank, a take-up machine, and a winder or a cutting machine can be used. In addition to this, an apparatus generally used in extrusion molding can be provided.

  Also, the extrusion machine used for foam molding is not particularly limited, but a single or biaxial extruder generally used for extrusion molding can be used, and the screw diameter (D) is 10 mmφ or more, and the screw screw length. The thickness / screw diameter (L / D) is preferably 16 or more. The screw design is not particularly limited, but a screw design generally used in extrusion molding can be used, and a full flight type is preferable. When molding a foamed molded product with an extruder, it is important that the molded product is molded under appropriate conditions. The molding conditions vary depending on the performance of the extruder and the shape of the molded product. A range of conditions for molding the thermoplastic resin can be used, and the resin temperature is preferably 140 to 220 ° C, particularly 150 to 200 ° C.

  In addition, it is also possible to shape | mold a base resin previously and to make it adhere | attach on this, extruding the resin composition for polystyrene-type resin coating of this invention.

  Further, in the two-color molding, the polystyrene-based resin coating resin composition of the present invention is placed in a mold in which a molded body of a base resin preformed in the mold or outside the mold is disposed, according to a conventional method. What is necessary is just to carry out injection molding.

  The coated molded product of the present invention is particularly suitably used for automobile parts, OA equipment, and housing-related parts. Here, examples of the automobile parts include instrument panel skins for in-mold molding by sheet molding (hereinafter, vacuum molding), back garnish, side molding by profile extrusion molding, and the like. Examples of the OA device include a printer housing by in-mold molding. Housing-related parts include exterior parts such as sash parts by profile extrusion, carport parts, and resin-made bamboo fences.

EXAMPLES Hereinafter, although a manufacture example, an Example , a reference example, and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the following, “part” and “%” are based on mass unless otherwise specified.

  Moreover, in the following, each evaluation of the obtained resin composition is a value measured as follows.

[Surface gloss]
Using the digital variable angle photometer “UGV-5D” manufactured by Suga Test Instruments Co., Ltd., the reflectance at an incident angle of 60 ° and a reflection angle of 60 ° was measured on the surface of the obtained molded product.

[Formability]
<Thickness uniformity>
A rectangular plate-like body is cut out from the obtained molded product, and in the cross section, it is visually observed whether the coating layer formed of the polystyrene-based resin coating resin composition has a uniform thickness on all four sides. The case where no time was required for taking out and good products could be obtained was indicated as “◯”, the case where time required for taking out the conditions was indicated as “Δ”, and the case where unevenness was uneven was indicated as “X”.

<Surging phenomenon>
A sample in which the material flowed stably from the die of the coating mold extrusion molding machine was indicated by ◯, and a material that pulsated and flowed by ×.

[durability]
<Adhesion>
A 2 cm square cut was made on the surface layer material (coating layer made of a polystyrene-based resin coating resin composition) side of the coated molded product, and judged by the difference in the degree of adhesion at the interface between the surface material and the base material (PS resin) .
Judgment criteria are those that are peeled off after molding (not in close contact) and those that can be easily peeled by inserting a cutter knife blade at the interface, and those that do not peel even if a cutter knife blade is inserted at the interface In the case of ◯ and x, the adhesion strength was not sufficient, and in the case of ◯, the adhesion strength was sufficient and it was accepted.

<Chipping resistance>
The coated molded product was cut with an electric circular saw perpendicular to the extruding direction. The surface layer material on the cut surface did not have chipping or peeling, and the chipping with both chipping and peeling was marked with x.

<Heat cycle properties>
After the coated molded product was subjected to the following heat cycle conditions 1 and 2, the surface layer material and the base material were observed for blistering, deformation, and peeling, and evaluated according to the following criteria.
Condition-1: Using a constant temperature bath with a humidity of 40%, −30 ° C. × 1 hour → 23 ° C. × 30 minutes → 70 ° C.
X 1 hour → 23 ° C x 30 minutes as 1 cycle, 10 cycles Condition-2: Use a thermostatic bath with 80% humidity, -30 ° C x 1 hour → 23 ° C x 30 minutes → 70 ° C
× 1 hour → 23 ° C × 30 minutes as one cycle, 10 cycles ○: No blistering, deformation, or peeling.
X: Any of blistering, deformation, and peeling occurs.

[Production of Graft Copolymer (A)]
<Production Examples 1 to 4: Production of Graft Copolymers (A-1) to (A-4)>
In a reactor equipped with a reagent injection container, a condenser, a jacket heater and a stirrer, 200 parts of ion-exchanged water (including water in the rubbery polymer tex), 0.3 part of disproportionated potassium rosinate ( Solid content), ferrous sulfate heptahydrate 0.01 part, sodium pyrophosphate 0.2 part, and crystalline glucose 0.5 part, and after dissolving completely, the rubbery polymer a shown in Table 1 -1 was mixed in the amount shown in Table 2 in terms of solid content.

While stirring the contents in the reactor, the temperature was raised to 65 ° C., and the vinyl monomer shown in Table 2 and the chain transfer agent tert-dodecyl mercaptan and the polymerization initiator cumene hydroperoxide were continuously added. It was dropped and supplied to cause graft polymerization. Meanwhile, the jacket temperature was controlled so as to keep the reactor internal temperature at 65 ° C.
After completion of the dropwise addition, the temperature was raised to 70 ° C. and maintained for 1 hour to complete the graft polymerization reaction. After cooling, an antioxidant (dilauryl thiodipropionate) was added to obtain a latex of graft copolymer.

  The obtained graft copolymer latex was put into a 2.5% aqueous sulfuric acid solution (80 ° C.) in a volume of 1 times with stirring, and further held at 90 ° C. for 5 minutes to coagulate to obtain a graft copolymer. A slurry was obtained. The slurry was washed twice with water and dehydrated twice, and then allowed to stand at 70 ° C. overnight and dried to obtain milky white powder graft copolymers (A-1) to (A-4).

[Production of vinyl copolymer (B)]
<Production Examples 5 to 9: Production of vinyl copolymers (B-1) to (B-5)>
Using acrylonitrile and styrene in the proportions shown in Table 3, acrylonitrile-styrene copolymers (B-1) to (B-5) having a mass average molecular weight shown in Table 3 were produced by known suspension polymerization.

[Examples 1 to 11 , Comparative Examples 1 to 5, Reference Examples 1 to 3 ]
Obtained in the graft copolymers (A-1) to (A-4) or HIPS (“H450” manufactured by Toyo Polystyrene Co., Ltd.) obtained in Production Examples 1 to 4 and Production Examples 5 to 9 above. To 100 parts of a mixture obtained by mixing the obtained vinyl copolymers (B-1) to (B-5) in the ratios shown in Tables 4 and 5, 0.7 part of a lubricant is mixed and melted by a Banbury mixer. It knead | mixed and pelletized.
Using the pellets obtained in each Example, Comparative Example, and Reference Example, the above-described evaluation test was performed, and the results are shown in Tables 4 and 5.

  The surface gloss and moldability were evaluated using a 40 mm extruder, a 25 mm extruder and a modified extruder consisting of a lattice type, and a polystyrene resin composition pellet "G210C" manufactured by Toyo Styrene Co., Ltd. as a base resin. As a coating layer material, a coating molded product obtained by two-layer profile extrusion molding using the pellet-shaped polystyrene resin coating resin composition obtained in each Example, Comparative Example, and Reference Example was performed. It was.

[Discussion]
As is apparent from Tables 4 and 5, the polystyrene-based resin-coated resin compositions of Examples 1 to 11 satisfying the claims of the present invention have good adhesion between the coating layer and the substrate, chipping resistance, and heat cycle properties. Both are excellent.
Furthermore, from the comparison of Examples 4, 7, 8, 9, and Reference Example 10, the content of the vinyl cyanide monomer in the vinyl monomer mixture used in the vinyl copolymer (B) is 5 to 23 masses. It can be seen that a matte molded product having a low gloss on the surface of the molded product can be obtained when a product in the range of% is used.

On the other hand, since the polystyrene-type resin-coated resin compositions of Comparative Examples 1 to 4 do not satisfy the requirements of the claims of the present invention, the adhesion between the coating layer and the base resin, chipping resistance, heat cycle property Inferior to
In addition, Reference Examples 1 and 2 using HIPS instead of the graft copolymer (A) according to the present invention are affected by the content of the vinyl cyanide monomer in the vinyl copolymer (B) used together. Therefore, there are cases where adhesion cannot be expressed, and the application is limited.
On the other hand, the graft copolymer (A) according to the present invention can exhibit good adhesion regardless of the amount of the vinyl cyanide monomer of the vinyl copolymer (B).

  The resin composition for coating a polystyrene-based resin and a coated molded article of the present invention are useful for automobile interior parts, OA equipment, housing-related, exterior parts, and the like.

Claims (2)

In a resin composition for forming a coating layer on a substrate made of polystyrene resin,
Graft copolymer (A) obtained by polymerizing a vinyl monomer mixture containing at least an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of a rubbery polymer, and at least an aromatic vinyl monomer And a vinyl monomer mixture comprising a vinyl copolymer (B) obtained by copolymerizing a vinyl monomer mixture containing a vinyl cyanide monomer, and used for the graft copolymer (A) The vinyl cyanide monomer content in the vinyl copolymer (B) is 5 to 20% by mass, and the vinyl cyanide monomer content in the vinyl monomer mixture used in the vinyl copolymer (B) is 5 to 23%. A resin composition for coating a polystyrene-based resin, wherein the resin composition is mass%. A coated molded article comprising: a base material made of a polystyrene-based resin; and a coating layer formed on the base material using the polystyrene-based resin coating resin composition according to claim 1 .