JP3340155B2 - Thermoplastic resin composition and freon-resistant refrigerator parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having excellent impact resistance, rigidity, dimensional stability, moldability, glossiness and appearance, and excellent CFC resistance, and CFC-resistant refrigerator parts. About. Further, specifically, by using an acrylate polymer as one component of the thermoplastic resin composition, the chlorofluorocarbon resistance is high, and particularly, it is high with respect to the chlorofluorocarbon compounds HCFC-141b and HCFC-123. The present invention relates to a refrigerator component having environmental stress crack resistance, and the “refrigerator component” in the present invention includes the interior and exterior of the refrigerator door and the inner box.

[0002]

2. Description of the Related Art In general, styrene resins represented by ABS resins are excellent in high impact resistance, rigidity, dimensional stability, moldability, gloss and appearance, and are widely used as industrial parts and household electric products. ing. The ABS resin is, for example, CFC- which is a foaming agent of foamed rigid urethane used for insulation between an outer box and an inner box of a home refrigerator.
It is used as a material for inner boxes of refrigerators because it has resistance to environmental stress cracking. In recent years, the box part on the side that mainly stores the food of the refrigerator is made into a heat-insulated box by injecting the foamed hard urethane stock solution into the space of both boxes formed by combining the inner box and the outer box, and solidifying the foam. .

[0003] The outer box of the refrigerator mainly uses an iron plate, and the inner box is usually manufactured by vacuum forming a sheet-like flat plate of ABS resin. Vacuum forming is a kind of thermoforming method, and general-purpose ABS resin is easily formed without heat discoloration. The inner box obtained by vacuum forming often has an average thickness of less than 1 mm, and an ABS resin having a somewhat higher elastic modulus is used because it can prevent deformation of the inner box. Further, the foamed rigid urethane resin filled between the inner box and the outer box of the refrigerator is made of ABS, which is the inner box.
Adhered to the resin and the iron plate that is the outer box, the refrigerator is
Since a heat radiation effect accompanies the operation, stress distortion occurs due to the difference in the linear expansion coefficient between the ABS resin / foamed hard urethane / iron plate.

As a foaming agent for the foamed rigid urethane resin, a chlorofluorocarbon-based compound (eg, CFC-11, CFC-12, HCFC
-141b, HCFC-123, etc.). The CFC-based compound is contained in the foam cell in a gaseous state even after the urethane foaming, and is always in contact with the ABS resin vacuum formed body as the inner box. And cause crazing.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks. The present invention relates to a resin composition containing two specified ABS resins and an acrylate ester resin as main components, and a resin composition comprising the same. Molded articles formed using, for example, inner boxes used as refrigerators have high impact resistance and rigidity, dimensional stability, moldability, gloss and appearance, and as a foaming agent in the space between the outer box and the inner box. Injects a hard urethane stock solution using a chlorofluorocarbon-based compound, and has excellent environmental stress cracking resistance without cracking or crazing even when it comes into contact with the chlorofluorocarbon-based compound contained in the foam cell after urethane foaming. And completed the present invention.

[0006]

SUMMARY OF THE INVENTION In summary of the invention, the present invention provides high impact and rigidity, dimensional stability, moldability ,
The invention relates to a resin composition having excellent gloss and appearance, and also having excellent CFC resistance (environmental crack resistance) and a CFC-resistant refrigerator component, wherein 90% by weight or more of the particle diameter is 0.01 μm.
A monomer comprising 50 to 75% by weight of an aromatic vinyl monomer and 25 to 50% by weight of a vinyl cyanide monomer in the presence of 20 to 70 parts by weight of a conjugated diene rubber polymer of mixture
Graft copolymer (A) component obtained by polymerizing 30 to 80 parts by weight, 90% by weight or more of the particle diameter is 0.2 μm to 0.5 μm.
m in the presence of 20 to 70 parts by weight of a conjugated diene-based rubber polymer consisting of 50 to 75% by weight of an aromatic vinyl monomer and 25 to 50% by weight of a vinyl cyanide monomer. The graft copolymer (B) component obtained by polymerizing ~ 80 parts by weight and the content of the aromatic vinyl monomer are 50 to 75% by weight.
Ri, aromatic vinyl monomer and a vinyl cyanide monomer and 必
If necessary, a copolymer (C) obtained by copolymerizing a copolymerizable monomer and a homopolymer of an acrylate monomer or a monomer copolymerizable with an acrylate monomer A polymer or copolymer (D) having a glass transition temperature of 20 ° C. or lower and a conjugated diene system occupying the entire mixture. A thermoplastic resin composition characterized in that the content of the rubber polymer is 10 to 20% by weight, and a CFC-resistant refrigerator component obtained by molding the thermoplastic resin composition.

[0007] The components of the graft copolymer (A) component (hereinafter referred to as component (A)) and the graft copolymer (B) component (hereinafter referred to as component (B)) of the present invention comprise a conjugated diene rubber polymer, An aromatic vinyl monomer and a vinyl cyanide monomer.

The conjugated diene rubber polymer constituting the component (A) and the component (B) includes a homopolymer and a copolymer.

The conjugated diene rubber homopolymer includes polybutadiene, isoprene, 2-chloro-1,3 butadiene, 1-chloro-1,3 butadiene, piperidine, dimethylbutadiene and chloroprene.

[0010] Examples of the conjugated diene rubber copolymer include a styrene-butadiene copolymer and an acrylonitrile-butadiene copolymer.

One or more of these conjugated diene rubber polymers are used, and are preferably polybutadiene and / or a styrene-butadiene copolymer having a styrene content of 20% by weight or less.

The conjugated diene rubber polymer used for the components (A) and (B) of the present invention has a gel content of 70%.
It is preferably at least 80% by weight in the component (A), and preferably at least 75% by weight in the component (B). 70% by weight gel content of conjugated diene rubber polymer
If it is less than 30, the excellent balance between impact resistance and molding workability, which is the object of the present invention, cannot be obtained.

[0013] The gel content means that a diene-based rubber polymer is precipitated by adding methyl alcohol to a diene-based rubber polymer latex and dried to obtain a rubber polymer. next,
1 g of the obtained rubber polymer is dissolved in 100 ml of toluene, left at room temperature for 24 hours, separated into an insoluble portion and a soluble portion, and the weight% of the insoluble portion is defined as the gel content.

In the component (A), 90% by weight or more of the conjugated diene rubber polymer has a particle diameter of 0.01 μm to 0.1 μm.
It is. As for the particle diameter, the impact resistance tends to decrease as the number of fine particles less than 0.01 μm increases, and the rigidity and moldability tend to decrease as the number of large particles exceeding 0.1 μm increases.

In the component (B), 90% by weight or more of the conjugated diene rubber polymer has a particle diameter of 0.2 μm to 0.5 μm.
It is. When the particle size is less than 0.2 μm, the balance between impact resistance and rigidity becomes poor, and 0.5 μm
When the number of coarse particles exceeding m increases, the appearance, particularly the gloss, decreases.

Examples of the aromatic vinyl monomer constituting the component (A) and the component (B) include styrene, α-methylstyrene, dimethylstyrene, t-butylstyrene, and halogenated styrene. Alternatively, two or more kinds can be used. In particular, styrene is preferred as the aromatic vinyl monomer.

Examples of the vinyl cyanide monomer constituting the component (A) and the component (B) include acrylonitrile and methacrylonitrile, and one or more of these can be used. In particular, acrylonitrile is preferred as the vinyl cyanide monomer.

As the graft copolymer constituting the components (A) and (B) of the present invention, copolymerizable vinyl monomers other than those described above can be used if necessary. Examples of the copolymerizable vinyl monomer include methyl methacrylate, methyl acrylate, acrylamide, methacrylic acid, and acrylic acid, and one or more of these can be used.

Examples of the polymerization method for obtaining the components (A) and (B) include a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk polymerization method and a polymerization method based on a combination thereof.

When the total amount of each of the components (A) and (B) is 100 parts by weight, both the components (A) and (B) contain 20 to 70 parts by weight of the conjugated diene rubber polymer. , Preferably 40 to 70 parts by weight. Conjugated diene rubber polymer is 20
If the amount is less than part by weight, the productivity at the time of industrial production as a graft copolymer deteriorates. On the other hand, if the amount exceeds 70 parts by weight, graft polymerization with the above-mentioned monomer becomes difficult, and a graft copolymer having a constant graft ratio cannot be obtained.

When the total amount of the components (A) and (B) is 100 parts by weight, both the aromatic vinyl monomer and the vinyl cyanide monomer are used for the components (A) and (B). Is 30 to 80 parts by weight, preferably 30 to 60 parts by weight. The ratio of the aromatic vinyl monomer to the vinyl cyanide monomer is preferably 50 to 75% by weight for the aromatic vinyl monomer and 50 to 25% by weight for the vinyl cyanide monomer.

The graft ratio is determined by the formula: weight of the above-mentioned monomer graft-polymerized on the conjugated diene rubber polymer / weight of the conjugated diene rubber polymer × 100 (% by weight).

The graft ratio of each of the components (A) and (B) of the present invention is 20% or more and less than 60%. If it is less than 20%, the impact resistance is sharply reduced, and if it is more than 60%, the moldability is significantly reduced.

The ratio of component (A) to component (B) of the present invention is from 10 to 70% by weight to 90 to 30% by weight, particularly preferably from 10 to 50% by weight to 90 to 50% by weight. If it exceeds this range, the balance between impact resistance and moldability is poor, which is not preferable.

The component (C) of the copolymer of the present invention (hereinafter referred to as (C)
Component)) are an aromatic vinyl monomer, a vinyl cyanide monomer, and a copolymerizable monomer as required .

As the aromatic vinyl monomer constituting the component (C), styrene, α-methylstyrene, dimethylstyrene, t-butylstyrene, halogenated styrene and the like are exemplified. Can be used. In particular, styrene is preferred as the aromatic vinyl monomer.

Examples of the vinyl cyanide monomer constituting the component (C) include acrylonitrile and methacrylonitrile, and one or more of these can be used. In particular, acrylonitrile is preferred as the vinyl cyanide monomer.

As the component (C), another copolymerizable vinyl monomer can be added if necessary. Examples of the copolymerizable vinyl monomer include methyl methacrylate, methyl acrylate, acrylamide, methacrylic acid, and acrylic acid, and one or more of them can be used.

The component (C) is a monomer in the entire component (C).
Is 50 to 75% by weight of the aromatic vinyl monomer, 50 to 25% by weight of the vinyl cyanide monomer and, if necessary, 0 to 25 % by weight of a vinyl monomer copolymerizable therewith. If they are coalesced, the same copolymer or a mixture of different copolymers
Is also good.

When the content of the aromatic vinyl monomer is less than 50% by weight,
Molding characteristics are inferior, and when it exceeds 75% by weight, impact resistance and chemical resistance are inferior, which is not preferable.

If the amount of the vinyl cyanide monomer is less than 25% by weight, the chemical resistance and impact resistance are poor, and if it exceeds 50% by weight, the hue stability at the time of molding is inferior.

If the amount of the copolymerizable vinyl monomer exceeds 25 % by weight, the overall balance of processability, heat resistance, impact resistance, chemical resistance and the like is inferior, which is not preferable.

The polymerization method of the component (C) includes a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk polymerization method and a polymerization method based on a combination thereof. Among these, a suspension polymerization method and an emulsion polymerization method are preferred.

The composition of the polymer (D) component (hereinafter referred to as component (D)) comprising the homopolymer and the copolymer of the present invention is as follows:
Acrylic ester monomers and monomers copolymerizable therewith.

As the acrylate monomer constituting the component (D), for example, methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, decyl acrylate, octadecyl acrylate, hydroxyethyl acrylate, methoxy acrylate Ethyl acrylate, glycidyl acrylate and phenyl acrylate.

Specific examples of the copolymerizable monomer constituting the component (D) include the following.

Examples of the methacrylate monomer include methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, decyl methacrylate, octadecyl methacrylate, hydroxyethyl methacrylate, methoxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate and the like. It is.

The amide monomers are acrylamide and methacrylamide, and the unsaturated carboxylic acid monomers are acrylic acid, methacrylic acid and itaconic acid. The fatty acid vinyl ester monomers are vinyl chloride. , Vinyl halide monomers such as vinylidene chloride, vinyl formate,
Vinyl acetate, vinyl propionate, vinyl decanoate and vinyl octadecanoate.

Examples of the olefin monomer include ethylene, propylene, 1-butene, isobutene and 2-butene.
Maleimide monomers include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-trailmaleimide and the like and acid anhydrides such as maleic anhydride. There is a body.

Conjugated diene monomers such as butadiene, isoprene and chloroprene; vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, hexyl vinyl ether, decyl vinyl ether, octadecyl vinyl ether, phenyl vinyl ether and cresyl vinyl ether And glycidyl vinyl ether. The vinyl ketone monomer is, for example, methyl vinyl ketone or phenyl vinyl ketone, but is not limited thereto.

Further, as the copolymerizable polyfunctional vinyl monomer constituting the component (D), divinylbenzene, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, , 4-butylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, cyanuric acid trial, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol Ethylene glycol di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate, pentaethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, tetradecaethylene glycol di (meth) acrylate, eicosaethylene glycol di (meth) acrylate, dipropylene glycol Di (meth) acrylate, pentapropylene glycol di (meth) acrylate, nonapropylene glycol di (meth) acrylate, tetradecapropylene glycol di (meth) acrylate, eicosapropylene glycol di (meth) acrylate, 1,6
-Hexanediol di (meth) acrylate and the like. Here, for example, ethylene glycol di (meth)
The acrylate indicates that it is ethylene glycol diacrylate or ethylene glycol dimethacrylate.

The mixing ratio of component (D) is from component (A)
The total amount of the component (D) is 1 to 15 parts by weight based on 100 parts by weight.
If the compounding ratio is less than 1 part by weight, environmental stress cracking property,
Insufficient cooling testability and poor CFC resistance. Also, 15
If the amount is more than 10 parts by weight, the flexural modulus and the melt flow are reduced, and the gloss is poor, making it impractical.

The component (D) of the present invention has a glass transition temperature.
It is 20 ° C. or less, preferably 10 ° C. or less. If the glass transition temperature exceeds 20 ° C., the chlorofluorocarbon resistance of the molded product decreases, and the environmental stress crack resistance becomes poor.

The gel content of component (D) is approximately the same as component (D).
1.0 g was precisely weighed (referred to as S1 g), put in a basket made of a 600-mesh stainless steel wire mesh, immersed in 100 g of toluene, left at 5 ° C. for 24 hours, and then lifted up the cage and allowed to stand at room temperature. (D) The weight (S2 g) of the insoluble polymer of the component (D) after air-drying is measured. Gel content = (S2 / S1) × 100 (% by weight)

The gel content of the component (D) is preferably 70% or less. If the gel content exceeds 70%, the CFC resistance of the molded article is lowered and the environmental stress crack resistance becomes poor. Is not preferred.

The method for producing the component (D) is not particularly limited, and known techniques such as emulsion polymerization, suspension polymerization, solution polymerization and bulk polymerization can be arbitrarily applied. Most advantageous.

Next, the resin composition of the present invention can be produced by the following method using a mixing apparatus. A method in which a polymer obtained by producing each of the component (A), the component (B), the component (C), and the component (D) is charged into a mixing device and mixed.

When the components (A), (B), (C) and (D) are all polymerized by emulsion polymerization,
A method in which the components (A) to (D) are mixed in the state of an emulsion, and then the polymer mixture mixed from the emulsion is separated.

After mixing the emulsion polymerization liquid of the component (A) and / or the component (B) with the emulsion polymerization liquid of the component (C) or the component (D) in an emulsion state, A method in which the remaining polymer of the components (A) to (D) is charged into a mixing device and mixed to obtain the polymer.

The components (A) and (B) and (C)
A polymer obtained by producing at least component (b),
A method in which the remaining component (a) of the component (C) and the component (D) are mixed in an emulsion state, and then a polymer mixture obtained by separation is charged into a mixing device and mixed.

The polymer mixture obtained by mixing the emulsion of the component (A) and / or the component (B) and the emulsion of the component (C) at least (b), A method in which the remaining component (a) and the component (D) are mixed in an emulsion state, and then a polymer mixture obtained by separation is charged into a mixing device and mixed.

A component (A) and / or a component (B);
The emulsion mixture obtained by emulsion polymerization of at least the components (a) and (D) of the component (C) is mixed in an emulsified state, and then the polymer mixture obtained by separation is mixed with the polymer residue (b). ) And the polymer of component (A) or component (B) are charged into a mixing device,
How to get mixed.

The component (C) (a) accounts for 5 to 30% by weight based on the total amount of the components (C) (a) and (b), and the polymer has an emulsifying weight. It is essential to be legal, while on the other hand, 95% to 70% by weight of the component (C) (b)
Does not limit the polymerization method, but an emulsion polymerization method is preferred.

The thermoplastic resin composition of the present invention provides good results in various physical properties when the composition obtained by the above-mentioned processes (1) to (4) is used as a molded article.

It is advantageous in the mixing step that all of the components (A) to (D) of the present invention are emulsion-polymerized, and it is desirable that the polymer obtained by a method other than the emulsion polymerization is in an emulsified state. .

The method of emulsifying the polymer is not particularly limited, and any method known in the art can be used. For example, a method of mixing and stirring a polymer with an emulsifier to form an emulsion, and then removing the solvent, There are a method of mixing and stirring a fine powder obtained by crushing a polymer with an emulsifier and water to form an emulsion, a method of crushing a polymer in the presence of an emulsifier and water to form an emulsion, and the like. Not as long.

The mixing method of the above-mentioned respective component polymer emulsions is as follows.
There is no particular limitation, and mixing can be performed using a device such as a fixed container type mixing device, a rotary container type mixing device, a pipeline mixer, and a static mixer.

The method for separating the polymer composition from the mixture of the above-mentioned respective component polymer emulsions is not particularly limited, and an acid such as hydrochloric acid, sulfuric acid, phosphoric acid and acetic acid, sodium chloride,
A method of adding a precipitant such as an electrolyte such as calcium chloride, aluminum chloride, sodium sulfate and magnesium sulfate, a water-soluble polymer such as polyvinyl alcohol, polyethylene glycol, a polyethylene glycol-polypropylene glycol block copolymer and carboxymethyl cellulose, and an emulsion. And a method of spraying an emulsion into a high-temperature gas.

The thermoplastic resin composition of the present invention is excellent in high impact resistance, rigidity, dimensional stability, moldability, gloss and appearance, and excellent in chlorofluorocarbon resistance. Can be used in a wide range of parts.

Further, since the thermoplastic resin composition of the present invention uses an acrylate polymer as one component, it is resistant to chlorofluorocarbon, especially HCF which is a fluorocarbon compound.
High environmental stress crack resistance to C-141b and HCFC-123. Refrigerator parts using the thermoplastic resin composition of the present invention, that is, in order to obtain physical properties suitable for the interior and exterior of the door of the refrigerator and the inner box of the refrigerator, a conjugated diene system occupying the entire thermoplastic resin composition. Rubber content 10
It is preferable to set it to 20% by weight.

If the content of the conjugated diene rubber is less than 10% by weight, the impact resistance is insufficient, so that cracks occur when the contents of the refrigerator are hit. The damage phenomenon is remarkable in a portion where the thickness is reduced by vacuum forming. On the other hand, when the content of the conjugated diene rubber exceeds 20% by weight, the rigidity is insufficient, so that the vacuum molded product is likely to be deformed.

In order to make the thermoplastic resin composition have a conjugated diene rubber content of 10 to 20% by weight, the components (A) and (B) having a conjugated diene rubber content of 20 to 70% by weight should have C)
The component and the component (D) are mixed and adjusted.

The mixing method for obtaining the thermoplastic resin composition of the present invention is as follows. The (A)-(D) component polymer or the polymer mixture obtained by the above-mentioned mixing apparatus is mixed with a Banbury mixer, It can be obtained by putting into a known mixer such as an extruder, a twin-screw extruder and a roll and mixing.

The thermoplastic resin composition of the present invention can be used to mold household articles, industrial articles and the like using molding methods such as injection molding, extrusion molding and vacuum molding. In order to mold refrigerator parts using the thermoplastic resin composition of the present invention, parts such as a refrigerator exterior and a tray are formed by injection molding, and the inside of the door and the inner box of the main body are formed by extrusion molding of an extruded sheet. Molding.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. All parts and percentages described in Examples and Comparative Examples are based on weight.

[0066]

【Example】

-Production of polybutadiene latex In a nitrogen-purged autoclave, butadiene, disproportionated potassium rosinate (emulsifier), potassium persulfate (polymerization initiator), dodecylmercaptan (chain transfer agent) and pure water were charged to carry out polymerization. Here, polybutadiene latexes having different particle sizes were obtained by changing the method of adding the emulsifier, the amount of the chain transfer agent used, the polymerization temperature and the reaction rate.
The distribution of the polybutadiene particle size in the obtained latex was measured by an electron microscope.

Production of Graft Copolymer [Components (A) and (B)] Polybutadiene latex in the proportions shown in Tables 1 and 2 was charged into a nitrogen-purged autoclave and heated to 50 ° C. 0.005 parts of ferrous heptahydrate, ethylenediamine 4
Dissolve 0.01 part of sodium acetate dihydrate and 0.3 part of sodium formaldehyde sulfone chelate dihydrate in 30 parts of pure water and inject. Then, add pure water to make the total amount of pure water 18 parts.
Five copies. Next, diisopropylbenzene hydroperoxide, dodecyl mercaptan, a monomer mixture of styrene and acrylonitrile, and an emulsifier solution (disproportionated potassium rosinate) in the amounts shown in Tables 1 and 2 were continuously added over 6 hours. Polymerization is performed, and the polymerization solution is heated to 70 ° C.
And the mixture was stirred for 2 hours to complete the polymerization.

[0068]

[Table 1]

[0069]

[Table 2]

The addition ratio of ferrous sulfate heptahydrate, sodium ethylenediaminetetraacetate dihydrate, sodium formaldehyde sulfone chelate dihydrate , diisopropylbenzene hydroperoxide , dodecyl mercaptan and disproportionated potassium rosinate were added. Is based on 100 parts of polybutadiene polymer solids and styrene and acrylonitrile monomers.

Production of Copolymer [Component (C)] Into a nitrogen-purged autoclave were charged 175 parts of pure water and 2 parts of potassium stearate, heated to 70 ° C., and mixed with a monomer having the composition shown in Table 3. The liquid and t-dodecyl mercaptan were added continuously over 4 hours. Further, lauroyl peroxide was added after the addition of the monomer mixture, and the mixture was stirred at 70 ° C. for 2 hours to terminate the polymerization.

[0072]

[Table 3]

The proportions of potassium stearate, lauroyl peroxide and t-dodecyl mercaptan are based on 100 parts of the monomer mixture.

Preparation of (co) polymer [Component (D)] In a nitrogen-purged autoclave, 140 parts of pure water and 2 parts of sodium dodecylbenzenesulfonate were charged and heated to 70 ° C., and 0.05 part of potassium persulfate was purified. An aqueous solution dissolved in 100 parts of water was poured, and a monomer mixture 10 having the composition shown in Table 4 was added.
0 parts and t-dodecyl mercaptan were added continuously over 4 hours. Further, after the addition of the monomer mixture, 0.1 part of diisopropylbenzene hydroperoxide was added to add 70 parts.
The polymerization was terminated by stirring at 2 ° C. for 2 hours.

[0075]

[Table 4]

The addition amounts of sodium dodecylbenzenesulfonate, potassium persulfate , diisopropylbenzene hydroperoxide and t-dodecylmercaptan are based on 100 parts of the monomer mixture.

The various physical properties were determined by the following methods. 1) Gel content: A solid obtained by dropping each emulsion of the components (A), (B), (C) and (D) in methanol was dried. Next, about 1.0 g thereof was precisely weighed (S
1 g), placed in a basket made of 600 mesh stainless steel wire mesh, and put component (A), component (B) or (D)
The component is 100 g of toluene, and the component (C) is 100 g
After being immersed in methyl ethyl ketone and left at 5 ° C. for 24 hours, the basket is pulled up, and the weight (S2 g) of the insoluble matter of each component after air-drying at room temperature is measured. Gel content = (S2 / S1) × 100 (% by weight)

2) Glass transition temperature: component (A)
After the solid obtained by dropping each of the emulsions of the component (B), the component (C) and the component (D) in methanol was dried, a 910 differential scanning calorimeter and a 990 thermal analyzer, which are DuPont type measuring machines, were used. It measured using. 3) Weight average molecular weight: HLC-8 manufactured by Tosoh Corporation
The measurement was performed by using two GMH-6 type columns manufactured by the same company in series with the 02A type gel permeation chromatography. As a detector, tetrahydrofuran was used as a solvent by using a refractometer.

Examples 1 to 17 The polymerization emulsions of the components (A) to (D) obtained by the above-mentioned production methods were used in the proportions shown in Tables 5 to 7 to obtain a mixture of the polymerization emulsions and the polymerization emulsions. After making the liquid, salting out was performed using calcium chloride to obtain each polymer mixture and polymer.
Next, the components (A) to (D) and the polymer mixture were melt-mixed using a twin-screw extruder to obtain a resin composition, and various physical properties were measured. Table 5 shows the measurement results.
It is shown in Table 7.

[0080]

[Table 5]

[0081]

[Table 6]

[0082]

[Table 7]

Comparative Examples 1 to 6 The same operation as in Example 1 was carried out except that the components (A) to (D) were changed to the proportions shown in Table 8, and various physical properties were measured after forming a resin composition. . Table 8 shows the measurement results.

[0084]

[Table 8]

Examples 18-19 Using the resin compositions of Examples 16 and 17, door caps and door handles attached to the top and bottom of a refrigerator door were molded using an injection molding machine. The product was obtained.

The various characteristic values were obtained by the following methods. 1) Conditions for measuring physical properties (1) Flexural modulus: ASTM D-790 This was used as an index of rigidity required for refrigerator components. (2) IZOD impact value: ASTM D-256 An index of impact resistance required for refrigerator components. (3) Melt flow value: JIS K-6874 was used as an index of moldability required for refrigerators.

2) Formability Measurement Conditions (1) Sheet Formability: A vacuum forming sheet for the inner box of the refrigerator door and the inner box of the refrigerator body was fitted with a T-die 40.
mm extruder at a take-up speed of 3 m / min,
Thickness 2.5 mm. A sheet having a width of 500 mm was produced. Next, the sheet was cut into pieces each having a length of 400 mm, and the gloss was measured. Those sheets that could not be formed at the time of extrusion molding were indicated by "x" in the table. Mitsuzawa: ASTM D-532

(2) Vacuum Formability: The sheet of (1) was subjected to vacuum forming with a vacuum forming machine under the following conditions to evaluate the vacuum formability. The evaluation was performed in the order of sheet expansion ratio, wall thickness distribution and mold transferability during vacuum forming, and A (excellent), B (excellent), C
(Good) and D (poor).

The unfolding magnification is 500 times or less for those that have not reached the bottom surface. The wall thickness distribution is calculated by dividing the average value of the wall thickness at the center of the square into three equal parts vertically and horizontally on one side of the molded product. The mold transferability was the average value of three points (24 points in total) at the center of eight ridge lines of each molded product divided into three equal parts.

Sheet size: 400 mm × 400 mm × 2.5 mm Expansion ratio setting: 500% Mold specification: Both bottom and opening are square shapes.
Each corner is 3R. Preheating condition setting: 150 ° C, 120 seconds

3) Conditions for measuring CFC resistance (1) Resistance to environmental stress cracking: A sheet obtained by extrusion molding was 30 m long.
A test piece compression-molded into a strip of m × 250 mm × 2 mm was placed on a 1/4 elliptical jig (maximum strain: 1.1%) and placed in an atmosphere of HCFC-123 or HCFC-141b at a temperature of 23 ° C. Leave to stand, 24 hours later visually determine the appearance of the test piece,
The strain (%) at the position where a crack or the like occurred was determined. In addition, HCFC-123 and HCFC-141b were carried out at an atmosphere concentration of 2 kg / m ³ and 4.7 kg / m ³ , respectively.

(2) Cooling test: Resin pellets were compression-molded into dumbbell pieces, hard urethane foaming was performed using HCFC-123 or HCFC-141b as a foaming agent, and the foam and the dumbbell pieces were bonded to form a test piece. did. In the measurement, the test piece was fixed to a jig in a state where tensile strain was applied to the test piece at 23 ° C., cooled to −30 ° C., and after 24 hours, the presence or absence of cracks and whitening was visually determined. The dumbbell test piece had a wide portion of 25 mm, a narrow portion of 5 mm, a length of 90 mm and a thickness of 0.5 mm, and the narrow portion had a width of 5 mm, a length of 40 mm and a thickness of 10 mm.
The foamed rigid urethane is bonded.

As is apparent from the comparative examples, when the conjugated diene rubber content deviates from the range of the present invention, the moldability and the environmental stress cracking resistance deteriorate, and the glass transition temperature of the D component deviates from the range of the present invention. Then, when the impact resistance is inferior and the monomer compositions of the components (A) and (B) deviate from the scope of the present invention,
Environmental stress cracking resistance is poor, and both are not preferred. Also,
When the glass transition temperature of the component (D) is out of the range of the present invention, the environmental stress cracking resistance at low temperatures is inferior and is not preferred. Generally, strain (%), which is a measure of environmental stress crack resistance, is 0.6%.
With the above, it is said that the possibility of occurrence of cracks or the like due to contact with Freon gas in normal use is small, and within the range of the present invention, it is better than this value.

[0094]

As described above, according to the present invention, the component (A)
By using four kinds of (co) polymers of the component (D), excellent impact resistance and rigidity, dimensional stability, moldability, gloss, and appearance are obtained. By using an acrylate polymer as one component, it has been applied to refrigerator components that have high chlorofluorocarbon resistance, especially high environmental stress cracking resistance to chlorofluorocarbon compounds HCFC-141b and HCFC-123. It is a thermoplastic resin composition having excellent CFC resistance and useful characteristics as a CFC-resistant refrigerator component that can be used.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 55/02 C08L 25/12 C08L 33/08

Claims (2)

(57) [Claims] (1) 90% by weight or more of the particle diameter is 0.01 μm to 0.1
In the presence of 20 to 70 parts by weight of a conjugated diene rubber polymer having a particle size of 50 μm, a monomer mixture 30 of 50 to 75% by weight of an aromatic vinyl monomer and 25 to 50% by weight of a vinyl cyanide monomer is used. ~ 80
Graft copolymer (A) component obtained by polymerizing parts by weight, fragrance in the presence of 20 to 70 parts by weight of a conjugated diene rubber polymer in which 90% by weight or more of the particle diameter is 0.2 μm to 0.5 μm. Group vinyl monomer 50-75% by weight and vinyl cyanide monomer 25-50
Graft copolymer obtained by polymerizing a monomer mixture of 30 to 80 parts by weight consisting of the weight% (B) component, the content of the aromatic vinyl monomer is 50 to 75 wt% der is, aromatic group vinyl monomer and vinyl cyanide monomer and respond as required
Flip and copolymerizable copolymer obtained the monomer by copolymerizing the component (C) and homopolymers or acrylic acid ester monomer and copolymerizable monomer in the acrylate monomer And a copolymer having a glass transition temperature of 20 ° C. or lower, or a copolymer (D) component. A thermoplastic resin composition characterized in that the combined content is 10 to 20% by weight. 2. A CFC-resistant refrigerator component obtained by molding the thermoplastic resin composition according to claim 1.