JP2996115B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to impact resistance, chemical resistance,
The present invention relates to a thermoplastic resin composition having an excellent balance of molding processability and having excellent thermal coloring stability during melting.

[0002]

2. Description of the Related Art Acrylonitrile-butadiene-styrene copolymer resin (ABS resin) has high impact resistance, chemical resistance,
It has an excellent balance of moldability and is widely used as a molding resin. For example, in the case of a material for an electric refrigerator, foamed polyurethane is used for a heat insulating layer of the electric refrigerator, and Freon is used as a foaming agent. Therefore, a resin material used in the vicinity of the heat insulating layer is required to have a property of not being attacked by chlorofluorocarbon, and an ABS resin is often used.

[0003] By the way, in recent years, regulations on chlorofluorocarbons related to environmental problems have been used as the above-mentioned foaming agents.
1b) is being used. Since this alternative fluorocarbon has a stronger erosion power of the resin than the conventional fluorocarbon, the above-mentioned resin material used near the heat insulating layer is required to have higher chemical resistance than ever.

In order to improve the chemical resistance of the ABS resin, it is known to increase the content of a vinyl cyanide monomer component in the resin composition. Plastic resin compositions have been proposed.

For example, in terms of merely improving the chemical resistance and the mechanical properties, a resin composition having a specified graft ratio of the graft copolymer (JP-A-4-258609, JP-A-5-78428, JP-A-5-78428, No. 5-78428), a high nitrile resin composition containing a methacrylic acid ester as an essential component as a matrix component in terms of having chemical resistance and excellent thermal stability (Japanese Patent Application Laid-Open No. 4-126775).
No. 6).

[0006] However, in the above-mentioned conventional high nitrile-containing thermoplastic resin composition, by increasing the content of the vinyl cyanide monomer component in the resin composition, the thermoplastic resin having excellent chemical resistance to some extent is obtained. Although the composition can be obtained, there is a new problem that the yellow color of the initial color tone of the resin molded product becomes strong and the quality is deteriorated.
For this reason, a high nitrile-containing thermoplastic resin composition excellent in both chemical resistance and thermal coloring stability upon melting has not yet been obtained, and the impact resistance, chemical resistance, and molding required for materials for electric refrigerators have not yet been obtained. At present, a resin material which has an excellent balance of processability and sufficiently satisfies the thermal coloring stability at the time of melting has not yet been obtained.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a high-quality ABS resin having a good balance of impact resistance, chemical resistance, and moldability, and sufficiently satisfying thermal coloring stability upon melting. The purpose is to provide.

The present inventors have developed a so-called high nitrile-containing thermoplastic resin composition in which the content of a vinyl cyanide monomer component is increased in order to achieve such an object. As a result of intensive studies on compatibility of the stability, the high nitrile-containing vinyl copolymer in which the ratio of the triple sequence of the vinyl cyanide monomer in the copolymer (II) as the matrix component is equal to or less than a certain value is high. It has been found that thermal coloring stability during melting is good while maintaining chemical resistance. Furthermore, the thermoplastic resin composition obtained by a specific combination of the novel high nitrile-containing vinyl copolymer and the rubber-containing graft copolymer (I) has an excellent balance between impact resistance and molding processability and has excellent resistance to molding. The inventors have found that both the chemical properties and the thermal coloring stability upon melting are excellent, and have reached the present invention.

[0009]

That is, according to the present invention, a rubbery polymer (a) is copolymerized with a vinyl cyanide monomer (b) and an aromatic vinyl monomer (c). 10 to 50 parts by weight of a rubber-containing graft copolymer (I) to which another possible vinyl monomer (d) is grafted, 25 to 55% by weight of a vinyl cyanide monomer (e),
75 to 45% by weight of an aromatic vinyl monomer (f) and another vinyl monomer component (g) copolymerizable therewith,
Copolymer (II) 50 to 9 containing 20% by weight as a constitutional unit
0 part by weight, and the ratio of the triple sequence of the vinyl cyanide monomer in the copolymer (II) is 10% by weight or less in the copolymer (II). It is a thermoplastic resin composition characterized by the above.

The rubbery polymer (a) used in the present invention is a diene rubber, an acrylic rubber, an ethylene rubber or the like. Specific examples thereof include polybutadiene, poly (butadiene-styrene), and poly (butadiene-styrene). (Acrylonitrile), polyisoprene, poly (butadiene-butyl acrylate), poly (butadiene-methyl acrylate), poly (butadiene-methyl methacrylate), poly (butyl acrylate-methyl methacrylate), poly (butadiene-acrylic acid) Ethyl), ethylene-propylene rubber, ethylene-propylene-diene rubber, poly (ethylene-isobutylene), poly (ethylene-methyl acrylate) and the like. These rubbery polymers are used in one kind or in a mixture of two or more kinds. Among these rubbery polymers, polybutadiene, poly (butadiene-styrene), poly (butadiene-acrylonitrile), and ethylene-propylene rubber are particularly preferably used. There is no limitation on the structure of the rubber, such as the particle diameter and the gel content.

In the present invention, specific examples of the vinyl cyanide monomer (b) include acrylonitrile and methacrylonitrile, and one or more of them can be used. Acrylonitrile is particularly preferred.

In the present invention, specific examples of the aromatic vinyl monomer (c) include styrene, α-methylstyrene, orthomethylstyrene, paramethylstyrene, para-t-butylstyrene, and halogenated styrene. And one or more kinds can be used. Styrene and α-methylstyrene are particularly preferred, and styrene is more preferred.

Specific examples of other vinyl monomers (d) copolymerizable in the present invention include unsaturated carboxylic acids such as acrylic acid and methacrylic acid; methyl acrylate, methyl methacrylate, butyl acrylate and the like. (Meth) acrylic esters; (meth) acrylamides such as acrylamide, methacrylamide, N-methylacrylamide and maleimide, N-methylmaleimide, N
Maleimides such as phenylmaleimide; and unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride and aconitic anhydride.

In the present invention, there are no particular restrictions on the composition ratio, graft ratio, particle size, etc., of the rubber-containing graft copolymer (I).

In the present invention, the monomer units of the high nitrile-containing vinyl copolymer (II) are composed of 25 to 55% by weight of a vinyl cyanide monomer (e) and 25 to 55% by weight of an aromatic vinyl monomer. (F) It must be 75 to 45% by weight. Preferably, the content is in the range of 30 to 45% by weight of the vinyl cyanide monomer (e) and 70 to 55% by weight of the aromatic vinyl monomer (f). 25 vinyl cyanide monomers (e)
When the amount is less than 5% by weight, the chemical resistance of the thermoplastic resin composition using the obtained copolymer is insufficient, and when it exceeds 55% by weight, the thermoplastic resin composition using the obtained copolymer is used. Both the processability of the product and the thermal coloring stability during melting are significantly reduced. If necessary, another copolymerizable vinyl monomer component (g) can be used as a constituent component, and the amount is preferably 0 to 20% by weight. If it exceeds 20% by weight, it becomes difficult to maintain the chemical resistance of the thermoplastic resin composition.

The vinyl cyanide monomer (e) used for the copolymer (II) in the present invention includes acrylonitrile and methacrylonitrile.
Species or two or more can be used. Acrylonitrile is particularly preferred. Examples of the aromatic vinyl monomer (f) include styrene, α-methylstyrene, orthomethylstyrene, paramethylstyrene, para-t-butylstyrene, and halogenated styrene. Can be used. Styrene and α-methylstyrene are particularly preferred, and styrene is more preferred. Other vinyl monomers (g) include unsaturated carboxylic acids such as acrylic acid and methacrylic acid; (meth) acrylic esters such as methyl acrylate, methyl methacrylate and butyl acrylate; acrylamide, methacrylamide (Meth) acrylamides such as N, N-methylacrylamide and maleimides such as maleimide, N-methylmaleimide and N-phenylmaleimide; and unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride and aconitic anhydride. be able to.

In the present invention, the triple sequence of the vinyl cyanide monomer in the copolymer (II) is a segment in the copolymer represented by the following (formula 1):

Embedded image In a state where the copolymer at about 200 ° C. is melted, an intramolecular cyclization reaction shown in the following (formula 2) proceeds, and the color changes.

[0018]

Embedded image The thermoplastic resin composition of the present invention relates to the copolymer (II), which is a constituent component, because the proportion of a triple sequence of a vinyl cyanide monomer that inhibits thermal coloring stability is as small as 10% by weight or less. It is presumed to be excellent in thermal coloring stability during melting. More preferably, it is less than 8% by weight. If it exceeds 10% by weight, the thermal coloring stability at the time of melting is inferior. The copolymer (II) in which the ratio of the triple sequence of the vinyl cyanide-based monomer is controlled to 10% by weight or less is the ratio of the vinyl cyanide-based monomer component in the remaining monomer. Can be produced by performing polymerization while controlling the temperature.

In the present invention, the reduced viscosity (ηsp / c) of the copolymer (II) is determined so as to further improve the chemical resistance of the resin composition using the obtained copolymer (II).
It is preferably 0.20 to 0.80 dl / g, and more preferably 0.40 dl / g or more. In order to further improve the moldability of the resin composition using the obtained copolymer (II), it is 0.80 dl / g or less, more preferably 0.70 dl / g or less. The reduced viscosity can be controlled by the amount of the chain transfer agent, the amount of the initiator, and the polymerization temperature.

In the present invention, the amount of the oligomer in the copolymer (II) is preferably 0.6% by weight or less in order to reduce mold fouling during molding. This is realized by using an aqueous suspension polymerization method as the polymerization method.

In the thermoplastic resin composition of the present invention, the compounding ratio of the rubber-containing graft copolymer (I) and the high nitrile-containing vinyl copolymer (II) is 100% by weight of the total of (I) and (II). Of the rubber-containing graft copolymer (I) is 10 to 50 parts by weight, preferably 20 to 50 parts by weight.
40 parts by weight, high nitrile-containing vinyl copolymer (II)
Is 50 to 90 parts by weight, preferably 60 to 80 parts by weight. If (I) is less than 10 parts by weight and (II) is more than 90 parts by weight, the resulting thermoplastic resin composition has poor impact resistance, which is not preferable. If (I) exceeds 50 parts by weight and (II) is less than 50 parts by weight, the resulting thermoplastic resin composition is inferior in chemical resistance.

In the present invention, if necessary,
Various antioxidants such as phenol, phosphorus and sulfur, weathering agents such as ultraviolet absorbers and light stabilizers, antistatic agents, lubricants such as ethylenebisstearylamide and metal soap, plasticizers, coloring agents, filling It is also possible to incorporate a reinforcing agent such as a glass fiber, carbon fiber, or the like, a flame retardant, or the like.

The thermoplastic resin composition of the present invention has impact resistance,
Excellent balance of chemical resistance and molding processability, and excellent thermal coloring stability when melted, suitable for various molding applications such as injection molding, sheet molding, extrusion molding, blow molding, compression molding, and vacuum molding. It is also suitable for coating, vacuum deposition, plating and the like of these processed products, but since it is excellent in both chemical resistance and thermal coloring stability upon melting, especially resin materials for electric refrigerators, such as those described above. It is suitable as a member such as a lining sheet, a door handle, a door cap, etc. used near the electric refrigerator heat insulating layer.

Hereinafter, an example of the method for producing the thermoplastic resin composition of the present invention will be described.

The method for producing the rubber-containing graft copolymer (I) is not particularly limited except for the conditions described in the claims. Emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, and combinations thereof Can be produced by a polymerization method.

The polymerization method for obtaining the high nitrile-containing vinyl copolymer (II) used in the present invention includes controlling the proportion of a vinyl cyanide monomer component in the residual monomer, reducing the amount of the oligomer, emulsifier, and solvent. Aqueous suspension polymerization is preferred from the viewpoint of inhibition of thermal coloring stability at the time of melting due to such auxiliary materials.

Examples of the suspension stabilizer used in the above polymerization include inorganic suspension stabilizers such as clay, barium sulfate and magnesium hydroxide, polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, methyl methacrylate / acrylamide copolymer and the like. And organic suspension stabilizers. Among them, organic suspension stabilizers are preferable in view of heat coloring stability at the time of melting, and more preferable is methyl methacrylate / acrylamide copolymer.

The total amount of water used as a dispersion medium per 100 parts by weight of the total amount of charged monomers used in the polymerization is to maintain good dispersibility of the monomer in water and to dissolve a large amount of the vinyl cyanide monomer in water. It is preferable to select from the range of 80 to 350 parts by weight from the viewpoint of preventing migration. From the viewpoint of controlling the ratio of the vinyl cyanide monomer component in the residual monomer, the amount is more preferably 100 to 200 parts by weight.

Examples of the polymerization initiator used in the polymerization include azonitriles such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobis (2,4,4-trimethylvaleronitrile). Compound and t-butyl peroxide, t-butyl peroxy neodecanoate, t-butyl peroxy neosexanoate, t-butyl peroxide
Organic peroxides such as butyl peroxypivalate and the like can be mentioned, and these can be used alone or in combination of two or more. Among them, azonitrile compounds are particularly preferable.

Examples of the chain transfer agent used herein include alkyl mercaptans such as n-octyl mercaptan, t-dodecyl mercaptan, and n-dodecyl mercaptan. These chain transfer agents can be used alone or in combination of two or more. The method of use may be any of batch addition, divisional addition, and continuous addition.

In order to obtain the copolymer (II) used in the present invention, the amount of the vinyl cyanide monomer remaining in the polymerization system from the start to the end of the polymerization must be controlled by controlling the ratio of the triple sequence of the vinyl cyanide monomer. When the ratio of the vinyl cyanide monomer component in the monomer is 9
It is preferable to control the content to 5% or less and to make the ratio of the vinyl cyanide monomer component in the residual monomer from the start of the polymerization to the point when the polymerization rate has passed 10% to 70% by weight or more and 95% by weight or less.

At least 10% of the polymerization rate from the start of the polymerization
If the ratio of the vinyl cyanide-based monomer component in the residual monomer up to the elapse point is 70% by weight or less, it becomes difficult to maintain the chemical resistance of the thermoplastic resin composition. This is because the chemical resistance, which is an advantage of the thermoplastic resin composition of the present invention, is based on the copolymer (II) which is a matrix component thereof.
The vinyl cyanide monomer component content is high when the ratio of the vinyl cyanide monomer component in the residual monomer from the start of polymerization to the point when the polymerization rate has passed 10% is maintained at 70% by weight or more. This is because it is expressed by the high nitrile copolymer component. That is, the polymerization rate is 10
% Of the vinyl cyanide-based monomer component in the residual monomer up to the time point of 70% by weight or less, since only a copolymer component having a low content ratio of the vinyl cyanide-based monomer component is generated, This is because it does not contribute to chemical resistance.

The high nitrile copolymer component described here is
This is a component which is obtained by dissolving the copolymer (II) in methyl ethyl ketone and then reprecipitating the solution by dropwise addition of cyclohexane, and can be quantified by FT-IR analysis of the vinyl cyanide monomer component ratio of the precipitate.

The proportion of the vinyl cyanide monomer component in the residual monomer can be determined by adding the polymerization initiator, adding a polymerization inhibitor, removing the vinyl cyanide monomer from the polymerization system by stripping or It can be controlled by adding a monomer other than the vinyl cyanide monomer component into the polymerization system during polymerization.

With respect to the thermoplastic resin composition of the present invention, the blending and melt extrusion of the copolymer (I) and the copolymer (II) are not particularly limited, and a generally known method can be employed. When compounding the rubber-containing graft copolymer (I) and the copolymer (II), for example, a ribbon blender, a V-type blender, a Henschel mixer, or the like can be used. The thermoplastic resin composition can be obtained by an extruder such as a single-screw extruder, a twin-screw extruder, or a kneading process using a Banbury mixer, a mixing roll, a pressure kneader, or the like.

[0036]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but these examples do not limit the present invention. Parts and% in Tables 1 to 3, Reference Examples, Examples and Comparative Examples represent parts by weight and% by weight, respectively. The physical properties of the obtained rubber-containing graft copolymer (I), copolymer (II) and thermoplastic resin composition were determined by the following test methods.

Reduced viscosity (ηsp / c) of copolymer (II)
Is the temperature of the water tank (measurement temperature) using an Ubbelohde viscometer.
Was adjusted to 30 ± 0.1 ° C., and calculated from the falling time of the measurement sample by the following equation 3. However, in Equation 3,
ts is the flow time of the measurement sample, t ₀ is the flow time of the measurement solvent, and C is the resin concentration (g / 1) of the measurement sample.
00 ml). As a measurement sample, a resin obtained by dissolving approximately 0.2 g of a precisely weighed resin in methyl ethyl ketone as a measurement solvent using a 50 ml volumetric flask was used.

Reduced viscosity (ηsp / c) = [(ts / t ₀ ) −1] / C (Formula 3) Unreacted monomer and copolymer (II) in the polymerization system for polymerization of copolymer (II) The amount of medium oligomer was measured using a gas chromatograph (GC-14A type) manufactured by Shimadzu Corporation. The AN copolymerization amount and the conversion were calculated by the following equations 4 and 5.

Amount of copolymerized vinyl cyanide monomer (% by weight) = (total vinyl cyanide monomer−unreacted vinyl cyanide monomer) / (total charged monomer amount) × 100 (formula 4) Ratio (% by weight) = (amount of charged monomer−amount of unreacted monomer) / amount of all monomers × 100 (Formula 5) The ratio of the triple sequence of the vinyl cyanide monomer in the copolymer (II) is ¹³ Taking advantage of the fact that the signal shift of the α-carbon of the vinyl cyanide monomer appearing in C-NMR is slightly different depending on the type of adjacent monomer, the ratio of the triple sequence was quantified from the signal integrated value. The measurement conditions are as follows.

Apparatus: JEOL JNM-GSX400 type Observation frequency: 100.5 MHz Solvent: DMSO-d ₆ concentration: 445 mg / 2.5 mL Chemical shift standard: Me ₄ Si Temperature: 110 ° C. Observation width: 20,000 Hz Data point: 32 K flip angle : 90 ° (21 μs) pulsedelaytime: 5.0 s Number of accumulations: 7400 or 8400 Decoupling: gated decoupling (without NOE) The content ratio (cyclohexane-insoluble matter) of the high nitrile copolymer component in the copolymer (II) is as follows: It was quantified by the method shown.

1 g of the copolymer (II) is dissolved in 40 g of methyl ethyl ketone, and 20 g of cyclohexane is added dropwise to the solution. After well stirring at 50 ° C., the mixture was allowed to stand at room temperature overnight, and then set at 30 ° C. in a constant temperature bath. The precipitated copolymer component was centrifuged, and the content ratio was determined from the dry weight.

The proportion of the vinyl cyanide monomer component in the high nitrile copolymer component was determined by the following method.
And hot pressing the copolymer component processed was subjected to the above and 30μm about a film-like, which from the ratio of the baseline level of absorbance peak occurring FT-IR analysis was 2260 cm ^-1 and 1600 cm ^-1 The ratio of the vinyl cyanide-based monomer component was determined using the calibration curve shown in Equation 6.

X = (R + 0.5874482) /0.07396422 (Formula 6) X: Ratio of vinyl cyanide monomer component (% by weight) R: Absorbance peak height ratio ｛= H (2260) / H (16
00)｝ The chemical resistance test method is a UL test piece obtained by injection molding of a thermoplastic resin composition (a test piece exclusively used for evaluating the US flammability standard,
(Width about 13mm, length about 126mm, thickness about 1.5mm)
Was immersed in a DOP at 30 ° C. for 24 hours, taken out, and taken out according to the quality of the test piece. ：: no change, ○: slight absorption, Δ: blistering,
X: Visual judgment was made as if there were significant blisters.

Izod impact strength (hereinafter abbreviated as IZOD)
Describes JIS for injection molded articles of thermoplastic resin composition
Performed according to K 7110 with 1/2 inch and notch. The melt flow rate (hereinafter abbreviated as MFR) of the thermoplastic resin composition was measured at a temperature of 220 ° C. and a load of 10 kgf according to JIS K 7210 (Method B).
The degree of yellowing (YI) is determined according to JIS for an injection molded article (square plate: 120 × 100 × 3 mm) of a thermoplastic resin composition.
According to K7103, tristimulus values X, Y, and Z were measured using a colorimetric colorimeter (ND-100) manufactured by Nippon Denshoku Industries Co., Ltd., and calculated by the following (Equation 7).

Yellowing degree (YI) = 100 (1.28X−1.06Z) Y (Formula 7) Examples and comparative examples are shown below. Table 1 shows the time-dependent change (in terms of polymerization rate) of the ratio of the vinyl cyanide monomer component in the residual monomer in the polymerization system from the start of polymerization to the end of polymerization for the copolymer (II). Table 2 shows the copolymer (II)
It is various property values of the reference example regarding. Table 3 summarizes the mixing ratio of the rubber-containing graft copolymer (I) and the copolymer (II) and various physical properties of the thermoplastic resin composition.

Production of Rubber-Containing Graft Copolymer (I) Reference Example 1 A reactor purged with nitrogen was charged with 120 parts of pure water and 0.5 part of glucose.
Part, sodium pyrophosphate 0.5 part, ferrous sulfate 0.0
05 parts and polybutadiene latex (rubber particle diameter 0.3 μm, gel content 85%) 50 parts (solid content conversion)
And the temperature inside the reactor was raised to 65 ° C. while stirring. When the internal temperature reached 65 ° C., the polymerization was started, and a mixture consisting of a monomer (35 parts of styrene and 15 parts of acrylonitrile) and 0.3 part of t-dodecylmercaptan was added.
It was dripped continuously over time. At the same time, 0.25 parts of cumene hydroperoxide and potassium oleate.
An aqueous solution consisting of 5 parts and 25 parts of pure water was continuously dropped over 7 hours to complete the reaction. The obtained graft copolymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain a powdery graft copolymer. The graft ratio of this graft copolymer was 45%, and ηsp / c of the resinous component was 0.68 dl / g.

Preparation of Copolymer (II) Reference Example 2-1 In a stainless steel autoclave having a capacity of 20 l and equipped with a baffle and a Fowler-type stirring blade, 0.05 part of a methyl methacrylate / acrylamide copolymer (particularly, Kosho 4
No. 5-24151) was dissolved in 165 parts of ion-exchanged water, stirred at 400 rpm, and the system was replaced with nitrogen gas. Next, 42 parts of acrylonitrile; O
Parts of styrene, 0.46 parts of t-dodecyl mercaptan, 0.39 parts of 2,2'-azobis (2,4-dimethylvaleronitrile), 0.05 parts of 2,2'-azobisisobutylnitrile. The mixed solution was added while stirring the reaction system, and a copolymerization reaction was started at 58 ° C. After a lapse of 15 minutes from the start of the polymerization, 54 parts of styrene were intermittently added over 110 minutes from a feed pump provided at the top of the autoclave. During this period, the reaction temperature was 58 ° C.
The temperature was raised to 65 ° C. After the intermittent addition of styrene to the reaction system was completed, the temperature was raised to 100 ° C. over 50 minutes. Thereafter, the reaction system was cooled, the polymer was separated, washed, and dried according to a conventional method to obtain a bead copolymer. The final polymerization rate was 95%, and the ratio of the vinyl cyanide-based monomer component in the residual monomer at the end of the polymerization was 90%.

Reference Example 2-2 Among the conditions of Reference Example 2-1, a mixed solution: acrylonitrile 28 parts styrene 12 parts t-dodecylmercaptan 0.33 parts 2,2'-azobis (2,4-dimethylvaleronitrile) 0 parts 2,2'-azobisisobutylnitrile 0.32 parts Additional addition of styrene: 60 parts Reaction temperature from initiation of polymerization to completion of additional addition: 65 ° C to 73 ° C, and the same as in Reference Example 2-1. Polymerization by the method,
A beaded copolymer was obtained. Reference Example 2-3 Among the conditions of Reference Example 2-1, mixed solution: acrylonitrile 50 parts Styrene 4 parts Additional addition of styrene: 46 parts, and polymerization was carried out in the same manner as in Reference Example 2-1.
A beaded copolymer was obtained. Reference Example 2-4 Among the conditions of Reference Example 2-1, mixed solution: acrylonitrile 42 parts Styrene 4 parts N-phenylmaleimide 5 parts Additional addition of styrene: 49 parts, and the same method as Reference Example 2-1 Polymerize with
A beaded copolymer was obtained. Reference Example 2-5 Among the conditions of Reference Example 2-1, a mixed solution: methacrylonitrile 42 parts Styrene 4 parts Additional addition of styrene: 54 parts, and polymerization was carried out in the same manner as Reference Example 2-1. ,
A beaded copolymer was obtained. Reference Example 2-6 Among the conditions of Reference Example 2-2, mixed solution: acrylonitrile 34 parts α-methylstyrene 9 parts Additional addition of styrene 39 parts Additional addition of α-methylstyrene: 18 parts, and Reference Example 2 Perform polymerization in the same manner as in -2,
A beaded copolymer was obtained. Reference Example 2-7 Under the conditions of Reference Example 2-1, 1.5 parts of t-dodecyl mercaptan was used, and polymerization was performed in the same manner as in Reference Example 2-1 to obtain a bead copolymer. .

Reference Example 2-8 Under the conditions of Reference Example 2-1, t-dodecyl mercaptan was used in an amount of 0.3 part, and polymerization was carried out in the same manner as in Reference Example 2-1. I got

Reference Example 2-9 Among the conditions of Reference Example 2-2, a mixed solution: acrylonitrile 24 parts Styrene 76 parts Styrene additional addition: 0 parts, and the polymerization was carried out in the same manner as in Reference Example 2-2. Do
A beaded copolymer was obtained. Reference Example 2-10 Among the conditions of Reference Example 2-1, the mixed solution was 42 parts of acrylonitrile, 3 parts of styrene, and the addition of styrene was 55 parts. Thereafter, polymerization was carried out in the same manner as in Example 2-1.
A beaded copolymer was obtained. Reference Example 2-11 Using a known bulk polymerization apparatus, a mixture composed of 62 parts of styrene, 38 parts of acrylonitrile, 10 parts of toluene, 0.2 part of N-octylmercaptan, and 0.01 part of t-butyl peroxide was placed in a polymerization tank. Continuously supplied, polymerization rate 75%
The polymerization was completed by setting the apparent polymerization rate to 99% by weight or more to obtain a copolymer.

Reference Example 2-12 Polymerization was carried out based on Example 1 in JP-A-3-227306. At the end of the suspension polymerization, the polymerization rate was 73%, and the ratio of the vinyl cyanide-based monomer component to the remaining monomers at the end of the polymerization was 97% by weight. FIG. 2 shows the ratio of the vinyl cyanide monomer component in the remaining monomer from the start of the polymerization to the completion of the polymerization. ηsp / c is 0.50 dl / g, methyl ethyl ketone 0.4
Wt% solution, 30 ° C.), and the ratio of the vinyl cyanide monomer component in the copolymer was 70% by weight.

Production of Thermoplastic Resin Composition The rubber-containing graft copolymer (I) produced in Reference Example 1 and the high nitrile-containing vinyl copolymer produced in Reference Examples 2-1 to 2-12 (II) and ethylenebisstearylamide were kneaded with a Henschel mixer in the proportions shown in Examples 1 to 8 and Comparative Examples 1 to 6 in Table 3 and then gutted at an extrusion temperature of 230 ° C. with a 40 mmφ extruder. Extruded into pellets. The obtained pellets were injection molded at a molding temperature of 230 ° C. and a mold temperature of 40 ° C. to prepare test pieces for evaluation.

From Examples 1 to 8, the thermoplastic resin compositions having the compounding ratios described in the claims of the present invention are excellent in balance between impact resistance and molding workability, and are stable in thermal coloring and chemical resistance when the resin is melted. It turns out that it is excellent in both sexes. In Examples 1 to 3, the composition ratio of the copolymer (II) was changed within the scope of the claims, and in Examples 4 to 6, the components of the copolymer (II) were changed within the scope of the claims. In Examples 7 and 8, the copolymer (II) ηsp / c was changed within the scope of the claims.

However, in Comparative Examples 1 and 4, the copolymer (II)
Since the composition ratio is out of the range described in the claims of the present invention, Comparative Example 1 is inferior in chemical resistance, and Comparative Example 4 is inferior in thermal coloring stability during resin melting. In Comparative Example 2, since the ratio of the triple sequence of the vinyl cyanide-based monomer exceeded 10% by weight, the YI value of the resin molded product was significantly higher than that of Example,
Poor thermal coloring stability during resin melting. Comparative Example 3
Since the proportion of the oligomer in the copolymer (II) exceeds 0.6%, the mold is significantly soiled at the time of molding as compared with the examples, which is not practical for molding. In Comparative Examples 5 and 6, since the compounding ratio of the rubber-containing graft copolymer (I) and the high nitrile-containing vinyl copolymer (II) was out of the range described in the claims of the present invention, Comparative Example 5 had impact strength. Comparative Example 6 is inferior in chemical resistance.

The following is clear from the examples and comparative examples. That is, the thermoplastic resin composition of the present invention,
In addition to moldability, it has excellent impact strength, low mold contamination, good chemical resistance, and excellent thermal coloring stability during melting. This is because the total amount of the rubber-containing graft copolymer and the vinyl cyanide-based monomer component is higher than a certain value in all copolymers. This is realized for the first time by the use of a specific combination with a copolymer having a low content.

[0056]

[Table 1]

[Table 2]

[Table 3]

[0057]

The thermoplastic resin composition of the present invention contains a rubber-containing graft copolymer and a high proportion of a vinyl cyanide-based monomer, has a low oligomer amount, and has a vinyl cyanide monomer component. Is characterized by the fact that a high nitrile-containing vinyl copolymer having a very low tri-sequence ratio is used in combination at a specific ratio. The thermoplastic resin composition has not only good moldability but also excellent resistance to molding. It has excellent impact resistance, less mold staining, good thermal coloring stability during melting, and excellent chemical resistance. The thermoplastic resin composition of the present invention is used for various molding applications requiring chemical resistance and impact resistance, and is particularly suitable as a resin material for electric refrigerators.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 25/00-25/12

Claims (6)

(57) [Claims] 1. A rubbery polymer (a) comprising a vinyl cyanide monomer (b) and an aromatic vinyl monomer (c) and / or
Or other vinyl monomers copolymerizable therewith (d)
Grafted rubber-containing graft copolymer (I) 1
0 to 50 parts by weight, and vinyl cyanide monomer (e) 25
To 55% by weight, aromatic vinyl monomer (f) 75 to 45
A thermoplastic resin composition comprising, by weight, 50 to 90 parts by weight of a copolymer (II) having a constitutional unit of 0 to 20% by weight of another vinyl monomer component (g) copolymerizable therewith. And the ratio of the triple sequence of the vinyl cyanide monomer in the copolymer (II) is
A thermoplastic resin composition, wherein the content is 10% by weight or less. 2. The thermoplastic resin composition according to claim 1, wherein the ratio of the triple sequence of the vinyl cyanide monomer in the copolymer (II) is less than 8% by weight. 3. The copolymer (II) contains 30 to 45% by weight of a vinyl cyanide monomer component (e), 70 to 55% by weight of an aromatic vinyl monomer component (f), and copolymers thereof. 3. The thermoplastic resin composition according to claim 1, which is a copolymer containing 0 to 20% by weight of another polymerizable vinyl monomer component (g). 4. The copolymer (II) has a reduced viscosity of 0.20 to 0.20.
3. The weight ratio is 0.80 dl / g.
Or the thermoplastic resin composition according to 3. 5. The method according to claim 1, wherein the proportion of the oligomer in the copolymer (II) is 0.6% by weight or less.
5. The thermoplastic resin composition according to 2, 3 or 4. 6. A material for an electric refrigerator comprising the thermoplastic resin composition according to claim 1, 2, 3 or 4.