JP2005314456A - Thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermoplastic resin composition in which chemical resistance, impact resistance, dimensional stability and durability in a high-humidity environment of a composition composed of a saturated polyester resin and an ABS-based resin are improved. <P>SOLUTION: The thermoplastic resin composition comprises 10-90 parts wt. of a saturated polyester resin (A) and 90-10 parts wt. of a graft copolymer obtained by polymerizing an aromatic vinyl monomer with another monomer copolymerizable with it in the presence of a rubber-like polymer [the total of the components (A) and (B) is 100 parts wt.]. The content of an alkali metal in the component (B) is ≤0.01 wt.%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic resin composition. Specifically, the present invention relates to a thermoplastic resin composition having an excellent balance of impact resistance, chemical resistance and moldability, and excellent durability in a high humidity environment.

ABS resin has excellent physical property balance and dimensional stability, and is used in a wide range of fields. However, cracks may occur when various detergents for kitchens, toilets, baths, etc. adhere to the ABS resin molded product, which has the disadvantage of being inferior in so-called chemical resistance.
On the other hand, a saturated polyester resin is known as a resin excellent in chemical resistance, but has a disadvantage that it is inferior in impact resistance, particularly notched impact strength, and inferior in dimensional stability.
Therefore, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 59-219362) and Patent Document 2 (Japanese Patent Publication No. 7-15037), an ABS resin and a saturated polyester resin are blended, and the excellent physical properties of the ABS resin are obtained. Techniques have been proposed to improve chemical resistance without loss. However, these compositions are concerned about the deterioration of the resin in the molding and use of the molded product in a high humidity environment, and especially when the blending ratio of the saturated polyester resin is large for dimensional stability and physical property stability, It is not necessarily a satisfactory material.
JP 59-219362 A Japanese Patent Publication No. 7-15037

  As a result of intensive studies on the improvement of the above-mentioned quality problems in the composition comprising a saturated polyester resin and an ABS resin, the present inventors have formulated a specific composition comprising a specific ABS resin and a saturated polyester resin. The composition of the ratio was found to be a composition excellent in chemical resistance, impact resistance, dimensional stability, and durability in a high humidity environment, and reached the present invention. It is.

In the saturated polyester resin / ABS resin composition, the present invention is characterized in that the content of alkali metal in the ABS resin to be blended is limited to a specific amount or less.
That is, the present invention is obtained by polymerizing 10 to 90 parts by weight of the saturated polyester resin (A) with an aromatic vinyl monomer and another monomer copolymerizable therewith in the presence of a rubbery polymer. The graft copolymer (B) comprises 90 to 10 parts by weight (provided that the total of (A) and (B) is 100 parts by weight), and the content of alkali metal in (B) is 0.01% by weight. % Or less of the thermoplastic resin composition or 10 to 90 parts by weight of the saturated polyester resin (A), and the aromatic vinyl monomer and other monomers copolymerizable therewith in the presence of the rubbery polymer 89.5 to 9.5 parts by weight of a graft copolymer (B) obtained by polymerizing styrene, and a copolymer (C) obtained by polymerizing an α-alkylstyrene monomer and a vinyl cyanide monomer 0.5 to 50 parts by weight [provided that (A), (B And (C) is 100 parts by weight], and a thermoplastic resin composition having an alkali metal content of 0.01% by weight or less in (B) and (C) is provided. .

The resin composition of the present invention has an excellent balance between chemical resistance and impact resistance, and further has an effect of being excellent in dimensional stability and durability in a high humidity environment.

Hereinafter, the thermoplastic resin composition of the present invention will be described in detail.
-Saturated polyester resin (A)-
Examples of the saturated polyester resin (A) constituting the thermoplastic resin composition of the present invention include polyethylene terephthalate, polytetramethylene terephthalate, polybutylene terephthalate, and the like, and one or more of them can be used. Of these, polyethylene terephthalate is particularly preferable.

-Graft copolymer (B)-
The rubbery polymer constituting the graft copolymer (B) is not particularly limited as long as it is a polymer showing rubbery properties, but polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, styrene- Diene (co) polymers such as butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, isobutylene-isoprene copolymers, hydrogenated rubbers of these diene (co) polymers, ethylene -Propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-butene-1-nonconjugated diene copolymer, acrylic rubber and the like.
Of these, polybutadiene, butadiene-styrene copolymer, ethylene-propylene-nonconjugated diene copolymer, and acrylic rubber are particularly preferable.

Examples of the aromatic vinyl monomer constituting the graft copolymer (B) include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinyltoluene, methyl-α-methylstyrene, brominated styrene, and the like. Among them, styrene and α-methylstyrene are particularly preferable.

Other monomers that can be copolymerized include vinyl cyanide monomer, (meth) acrylic acid ester monomer, unsaturated acid monomer, unsaturated acid anhydride monomer, maleimide monomer Examples include, but are not limited to, at least one monomer selected from the group of bodies.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, with acrylonitrile being particularly preferred. Examples of the (meth) acrylic acid ester monomer include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like, particularly methyl methacrylate and butyl acrylate. preferable. Examples of the unsaturated acid monomer include acrylic acid and methacrylic acid. As the unsaturated acid anhydride monomer, maleic anhydride is preferred. Examples of maleimide monomers include maleimide, N-methylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (4-hydroxyphenyl) maleimide, N-cyclohexylmaleimide, etc. N-phenylmaleimide is preferred.

Although there is no restriction | limiting in particular about the composition ratio of each component which comprises a graft copolymer (B), 1-80 weight part of rubber-like polymers, 10-89 weight part of aromatic vinyl monomers, and this can be copolymerized The other monomer is preferably 10 to 89 parts by weight (total 100 parts by weight), and particularly as other copolymerizable monomers, vinyl cyanide monomer and / or (meth) acrylic acid ester It is preferable to use a monomer.

In the present invention, the alkali metal content in the graft copolymer (B) must be 0.01% by weight or less, and if the content exceeds 0.01% by weight, In addition to the deterioration of the resin during molding and use of the molded product in a humidity environment, particularly when the blending ratio of the saturated polyester resin is large, the dimensional stability and physical property stability are lowered, which is not preferable. Especially preferably, it is 0.005 weight% or less.

The method for producing the graft copolymer (B) is not particularly limited, and usual known methods such as bulk polymerization, solution polymerization, bulk suspension polymerization, suspension polymerization, and emulsion polymerization can be used. Polymerization and bulk suspension polymerization are preferred.
Among these, in the emulsion polymerization method, it is necessary to use a considerable amount of an emulsifier in the polymerization step. For this, an alkali metal salt of a higher fatty acid, an alkali metal salt of sulfonic acid, or the like is often used. Of the polymerization initiators used in the emulsion polymerization method, a redox initiator using an organic peroxide may be used. In this case, an iron salt or the like is often used. Further, when the graft copolymer particles obtained after emulsion polymerization are coagulated, a high concentration of alkali metal or alkaline earth metal is often added for salting out.
Therefore, when the graft copolymer (B) used in the present invention is produced by an emulsion polymerization method, in order to reduce the alkali metal content remaining in the final product, in the coagulation step after emulsion polymerization, It is desirable to solidify using an acid. Examples of the acid that can be used in this case include hydrochloric acid and sulfuric acid. Thereby, mixing of the metal salt in a solidification process can be avoided. In addition, the alkali metal salt content can be reduced by increasing the amount of washing water or increasing the number of washings in order to enhance the washing conditions after coagulation. In particular, the washing water is used in a volume equal to or larger than the apparent volume of the graft copolymer particles to be washed, preferably 2 times or more, more preferably 3 times or more, and the washing-dehydration step is performed twice or more. It is preferable to repeat the treatment three times or more. Thereby, compared with the graft copolymer particle obtained by a normal emulsion polymerization method, the content of the alkali metal salt remaining in the final product can be greatly reduced.
In other polymerization methods, for example, butadiene rubber, which is a raw material used in bulk polymerization and solution polymerization, contains a small amount of alkali metal and alkali metal salt used in the polymerization step. For example, it is preferable to reduce the alkali metal content by strengthening the neutralization treatment with, for example, carbonic acid, citric acid or the like, and precipitating / separating it as a salt hardly soluble in water.

-Copolymer (C)-
In the present invention, a copolymer (C) obtained by further polymerizing an α-alkylstyrene monomer and a vinyl cyanide monomer can be used. Examples of the α-alkylstyrene monomer in the copolymer (C) include α-methylstyrene, α-ethylstyrene, methyl-α-methylstyrene, and the like, and one or more of them can be used. Of these, α-methylstyrene is particularly preferable. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and one or more of them can be used. Particularly preferred is acrylonitrile. The composition ratio of the α-alkylstyrene monomer and the vinyl cyanide monomer constituting the copolymer (C) is not particularly limited, but the final content of the α-alkylstyrene monomer is 50% by weight or more. It is preferable in terms of improving the physical property balance of the composition, and particularly preferably 50 to 90 weight.

In the present invention, when the copolymer (C) is used, the content of the alkali metal in the graft copolymer (B) and the copolymer (C) is 0.01% by weight or less. When the content exceeds 0.01% by weight, the resin deteriorates in the molding and use of the molded product in a high-humidity environment, and particularly when the blending ratio of the saturated polyester resin is large. Is not preferable because dimensional stability and physical property stability are lowered. Especially preferably, it is 0.005 weight% or less.

Further, the production method of the copolymer (C) is not particularly limited, and usual known methods such as bulk polymerization, solution polymerization, bulk suspension polymerization, suspension polymerization, and emulsion polymerization can be used. Solution polymerization and bulk suspension polymerization are preferred. In addition, when manufacturing by emulsion polymerization, it is necessary to reduce content of an alkali metal by the method similar to a graft copolymer (B).

In addition to the above components, the thermoplastic resin composition according to the present invention includes stabilizers, pigments, dyes, and the like at the time of resin mixing and molding depending on the purpose, as long as the physical properties are not impaired. Reinforcing agents (talc, mica, clay, glass fiber, etc.), colorants (carbon black, titanium oxide, etc.), UV absorbers, antioxidants, lubricants, mold release agents, plasticizers, antistatic agents, inorganic and organic Known additives such as antibacterial agents can be blended.
However, when using these additives, it is desirable to select and use one having a low alkali metal content.

Examples of the method for mixing the saturated polyester resin (A), the graft copolymer (B) and the copolymer (C) in the present invention include a method using a known kneader such as a Banbury mixer or an extruder. There is no limitation on the order of mixing, and it is possible to mix one component remaining after mixing two components in advance, as well as batch mixing of the three components.

[Example]
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these.

Based on the composition ratio shown in Table 1, the saturated polyester resin (A), the graft copolymer (B) and the copolymer (C) are kneaded together with a single screw extruder (set temperature: 250 ° C.) to obtain various compositions. It was. The saturated polyester resin (A), graft copolymer (B) and copolymer (C) used were obtained by the following method.

○ Saturated polyester resin (A)
Polyethylene terephthalate: Mitsui PET J125 manufactured by Mitsui Chemicals, Inc.

○ Graft copolymer (B)
Graft copolymers B-1 to B-4 were prepared by the following methods, respectively. The alkali metal content in the obtained graft copolymer was quantified by ICP method and atomic absorption method after ashing the sample and dissolving in pure water.
B-1: Plug flow tower reactor with a volume of 15 liters ("New polymer production process" (Industry Research Committee, Koji Saeki / Shinzo Omi), page 185, Mitsui Higashi, described in Fig. 7.5 (b) Copolymer using a continuous polymerization apparatus in which one 10-liter complete mixing tank is connected in series to a reaction tank of the same type as the pressure type and having C1 / C0 = 0.955 partitioned in 10 stages) B-1 was produced.
65 parts by weight of styrene, 22 parts by weight of acrylonitrile, 25 parts by weight of toluene, 13 parts by weight of butadiene rubber, 0.2 parts by weight of t-dodecyl mercaptan, 1,1-bis (t-butylperoxy) 3,3,5-trimethyl The raw material consisting of 0.05 part by weight of cyclohexane was continuously supplied to the continuous polymerization apparatus to carry out monomer polymerization. The first plug flow tower type reaction vessel was set at 100 ° C., and the second complete mixing vessel was set at 130 ° C. After supplying the polymerization solution from the second reaction tank to a devolatilizing apparatus comprising a preheater (180 to 270 ° C.) and a decompression chamber (5 kPaabs), a graft copolymer B-1 was obtained through an extruder. The alkali metal content in the obtained graft copolymer B-1 was 0.003% by weight.

B-2: Graft copolymer B-2 in the same manner as B-1, except that the butadiene rubber used as a raw material in B-1 is one that has been subjected to advanced alkali metal removal treatment in advance. Got. The alkali metal content in the obtained graft copolymer B-2 was 0.0005% by weight.

B-3: 50 parts by weight of polybutadiene latex (weight average particle size 0.3 μm, gel content 85%), 150 parts by weight of water, 0.1 part by weight of ethylenediaminetetraacetic acid disodium salt, sulfuric acid in a nitrogen-substituted polymerization reaction vessel A mixture comprising 0.001 part by weight of ferric iron and 0.3 part by weight of sodium formaldehyde sulfoxylate, heated to 60 ° C., and then composed of 14 parts by weight of acrylonitrile, 41 parts by weight of styrene and 0.2 part by weight of cumene hydroperoxide. Was continuously added over 3 hours and further polymerized at 60 ° C. for 2 hours to obtain a graft copolymer latex. Thereafter, the latex was salted out using 3.0 parts by weight of magnesium sulfate as a salting-out agent with respect to 100 parts by weight (solid content) of the latex, and then 1.5 times the volume of water of the graft copolymer particles was added and stirred. Then, after dehydrating and washing, it was dried to obtain a graft copolymer B-3. The alkali metal content in the obtained graft copolymer B-3 was 0.07% by weight.

B-4: A graft copolymer B-4 was obtained in the same manner as B-3, except that the steam distillation after polymerization and the coagulation and washing steps were changed as follows in B-3. . That is, steam was blown into the graft copolymer latex obtained after polymerization and steam distilled for 1 hour. The temperature of the latex at this time was 80 ° C. Further, after steam distillation, the washing operation is repeated three times by coagulating using 1.0 part by weight of sulfuric acid as a coagulant, adding 2.5 times the volume of water of the graft copolymer particles, stirring and dehydrating. It was. The alkali metal content in the obtained graft copolymer B-4 was 0.008% by weight.

○ Copolymer (C)
Copolymers C-1 to C-2 were prepared by the following methods, respectively.
C-1: A nitrogen-substituted polymerization reactor was charged with 130 parts by weight of pure water and 0.3 parts by weight of potassium rosinate, and then heated to 65 ° C. with stirring. Thereafter, 30 parts by weight of an emulsifier aqueous solution containing 70 parts by weight of α-methylstyrene, 30 parts by weight of acrylonitrile and 0.35 parts by weight of t-dodecyl mercaptan and 2 parts by weight of disproportionated potassium rosinate for 4 hours each. It was continuously added throughout. Thereafter, the polymerization system was heated to 70 ° C. and aged for 2 hours to obtain a copolymer latex. Then, after salting out using 100 parts by weight (solid content) of the latex using 2.5 parts by weight of magnesium sulfate as a salting-out agent, 1.5 times the volume of water of the copolymer particles is added and stirred. After dehydrating and washing, the product was dried to obtain a copolymer C-1. The alkali metal content in the obtained copolymer C-1 was 0.06% by weight.

C-2: A copolymer C-2 was obtained in the same manner as C-1, except that the steam distillation after polymerization and the coagulation and washing steps were changed as follows. That is, steam was blown into the copolymer latex obtained after polymerization and steam distilled for 1 hour. The temperature of the latex at this time was 80 ° C. Further, after the steam distillation, the washing operation of coagulating using 1.0 part by weight of sulfuric acid as a coagulant, adding water 2.5 times the volume of the copolymer particles, stirring and dehydrating was repeated three times. . The alkali metal content in the obtained copolymer C-2 was 0.005% by weight.

Table 1 shows the results obtained by preparing various test pieces from the various compositions thus obtained with an injection molding machine and evaluating the physical properties. In addition, each evaluation method is shown below.

○ Chemical resistance Molded product (disk shape with a diameter of 130mm and a thickness of 3mm) having a boss with an inner diameter of 3.2mm, an outer diameter of 9.0mm, and a height of 25mm at the center is molded by an injection molding machine. . Insert a JIS Class 2 M4 x 12 mm self-tapping screw and 1 mm thick washer into the boss of this molded product and screw it in with a torque of 15 kg · cm. Immerse and leave at room temperature for 1 hour. Thereafter, the molded product is taken out and the presence or absence of cracks is determined.
○ Impact resistance In accordance with ASTM D-256, an Izod impact value with a thickness of ¼ inch and a notch was measured.
○ Dimensional stability When the length of the long side (150 mm direction) of the obtained flat plate is L, the injection molding is performed with a flat plate mold having dimensions of 90 mm × 150 mm × 3 mmt. The evaluation was performed according to the value to be determined.
(150-L) / 150 × 1000 (Formula 1)
○ Test specimens and pellets are left in a high-temperature and high-humidity oven at 90 ° C / 95% RH, and the rate of change of the notched Izod impact value and the melt flow rate after the lapse of 1000 hours with respect to the value before leaving ( Retention rate) was evaluated.

As described above, the resin composition of the present invention has an excellent balance of chemical resistance and impact resistance as compared with the ABS resin alone and the saturated polyester resin alone, and further by using the ABS resin having a low alkali metal content. It also has excellent dimensional stability and durability under high-humidity environments, and can be widely used in the home appliance field, building material field, sanitary field, and the like.

Claims (5)

Graft copolymer obtained by polymerizing 10 to 90 parts by weight of saturated polyester resin (A) and an aromatic vinyl monomer and another monomer copolymerizable therewith in the presence of a rubbery polymer ( B) It consists of 90 to 10 parts by weight (provided that the total of (A) and (B) is 100 parts by weight), and the content of alkali metal in (B) is 0.01% by weight or less. A thermoplastic resin composition characterized by the above. 2. The thermoplastic resin composition according to claim 1, wherein the content of alkali metal in (B) is 0.005% by weight or less. Graft copolymer obtained by polymerizing 10 to 90 parts by weight of saturated polyester resin (A) and an aromatic vinyl monomer and another monomer copolymerizable therewith in the presence of a rubbery polymer ( B) 89.5 to 9.5 parts by weight, and 0.5 to 50 parts by weight of copolymer (C) obtained by polymerizing α-alkylstyrene monomer and vinyl cyanide monomer [provided that (A), (B) and (C) are 100 parts by weight in total], and the alkali metal content in (B) and (C) is 0.01% by weight or less. A thermoplastic resin composition. The thermoplastic resin composition according to claim 1, wherein the content of alkali metal in (B) and (C) is 0.005 wt% or less. The thermoplastic polyester composition according to any one of claims 1 to 4, wherein the saturated polyester resin is polyethylene terephthalate.