JPS643901B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a thermoplastic resin composition containing a rubber-containing styrenic resin that has excellent environmental stress cracking resistance and improved thermal stability. (Prior art) When rubber-containing styrenic resin comes into contact with chemicals under stress, it is observed that cracks occur and, in severe cases, breakage, but this phenomenon is considered to be an environmental stress cracking phenomenon. It is well known that this phenomenon is conspicuously observed in chemicals such as alcohols, carboxylic acids, alkanes, and alkenes that do not have high solubility in resins. This phenomenon occurs even when no external force is applied to the resin molded product, when the molding distortion that remains inside the molded product is released by contact with chemicals. It imposes a lot of restrictions. The content of the rubber component and the molecular weight of the resin component are known to be factors that affect the environmental stress cracking properties of rubber-containing styrenic resins. Although the environmental stress cracking property can be improved by increasing the size, the effect is insufficient for practical use. By the way, JP-A-56-147841 discloses a copolymer latex of an olefin monomer, a fatty acid vinyl ester monomer, and in some cases a vinyl monomer copolymerizable therewith, and a rubber-containing styrene resin. It is disclosed that a resin with markedly improved environmental stress cracking resistance can be obtained by mixing the same with latex in the latex state. However, although this method improves the environmental stress cracking resistance, it is necessary to use nonionic high molecular weight surfactants during the production of copolymer latex, that is, when emulsion copolymerizing monomers such as fatty acid vinyl esters. When using , it is difficult to precipitate the resin from the mixture of copolymer latex and rubber-containing styrenic resin latex, and it is necessary to administer a large amount of inorganic acid and/or water-soluble inorganic salt. This is not only disadvantageous in practice, but also undesirable because a large amount of the precipitating agent remaining in the resin recovered from the latex has an unfavorable effect on the thermal stability of the resin. (Problems to be Solved by the Invention) The present invention aims to improve this drawback, and in a composition of a rubber-containing styrenic resin (A) and a fatty acid vinyl ester polymer (B), precipitation Since there is no need to perform the difficult precipitation of the copolymer latex of component (B), the manufacturing process is simplified, and the large amount of precipitating agent that was used to precipitate the copolymer of component (B) can be saved. Since no addition is required, poor thermal stability of the resin due to residual precipitating agent is reduced, and a rubber-containing styrenic resin with excellent environmental stress cracking resistance and improved thermal stability can be provided. . (Means for Solving the Problems) That is, the present invention comprises: (A) 100 parts by weight of a rubber-containing styrenic resin; (B) a copolymer of an olefin monomer and a fatty acid vinyl ester monomer and/or A copolymer of the above two types of monomers and a copolymerizable vinyl monomer (hereinafter referred to as fatty acid vinyl ester polymer)
In the composition of 0.5 to 40 parts by weight, the fatty acid vinyl ester polymer is a solid obtained by drying a latex produced by an emulsion polymerization method without going through a precipitation process, and its gel content is is less than 50% by weight, and its solubility parameter is 8.8 to 9.7 (cal/cc) ^1/2 . Monomers constituting the rubber component of the rubber-containing styrenic resin that is component (A) of the present invention include conjugated diene monomers such as butadiene, isoprene, dimethylbutadiene, chloroprene, and cyclopentadiene, and 2,5-norbornadiene. , 1,4-cyclohexadiene, non-conjugated diene monomers such as 4-ethylidene norbornene, styrene monomers such as styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, methyl methacrylate, ethyl acrylate, butyl acrylate,
These include (meth)acrylic monomers such as hexyl acrylate and octyl acrylate, and olefin monomers such as ethylene, propylene, 1-butene, isobutylene, and 2-butene, and these monomers can be homopolymerized or copolymerized. Specific examples of rubber components include polybutadiene, polyisoprene, polychloroprene, polybutyl acrylate, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, and butadiene-styrene-methyl methacrylate copolymer. Examples include, but are not limited to, polymers such as ethylene-propylene-4-ethylidene norbornene copolymer, and ethyl acrylate-butyl acrylate copolymer. Additionally, polyfunctional vinyl monomers can be copolymerized during the polymerization of these rubber components, and polyfunctional vinyl monomers that can be used include divinylbenzene, ethylene glycol dimethacrylate, 1,3- Butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, propylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, glycidyl acrylate, glycidyl methacrylate and so on. There are no particular restrictions on the polymerization method of these monomers;
Known techniques such as emulsion polymerization and solution polymerization can be used. The rubber component in the resin of component (A) does not need to be of one type, and may be a mixture of two or more types of rubber components. Monomers constituting the resin component of the rubber-containing styrenic resin that is component (A) of the present invention include styrene monomers such as styrene, α-methylstyrene, and vinyltoluene, acrylonitrile, methacrylonitrile, and methyl (Meth)acrylic monomers such as methacrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, etc. are used in homopolymerization or copolymerization, but in order to obtain good molding processability, they must be at least 35% in weight. % or more of styrenic monomer is essential. The component (A) used in the present invention is composed of a rubber component and a resin component as described above, and a graft structure is present at the interface between the rubber component that has a spherical structure and the resin component that is a continuous phase. is necessary. It is known that such a structure can be achieved by a so-called graft polymerization method in which part or all of the monomers constituting the resin component are polymerized in the presence of a rubber component. can also be produced by known graft polymerization techniques. In order to adjust the content of the rubber component contained in the (A) component having a graft structure, it is possible to mix a separately polymerized resin component with the (A) component. The resin component does not need to have the same composition as the resin component obtained by graft polymerization.
For example, a resin component obtained by copolymerizing acrylonitrile-styrene-α-methylstyrene can be mixed with component (A) obtained by graft polymerizing acrylonitrile-styrene-methyl methacrylate in the presence of polybutadiene. The resin of component (A) used in the present invention is 2 to 30% by weight,
Preferably, the rubber component is 5 to 25% by weight. If the rubber content of component (A) is less than 2% by weight, the effect of improving the environmental stress cracking properties of the resin obtained by mixing with the copolymer of component (B) will be insufficient; If it exceeds this value, the rigidity and moldability will deteriorate, which is undesirable. A specific example of component (A) of the present invention is ABS
(acrylonitrile-butadiene-styrene) resin, heat-resistant ABS (acrylonitrile-butadiene-
Styrene-α-methylstyrene) resin, AAS (acrylonitrile-acrylic ester-styrene) resin, ACS (acrylonitrile-chlorinated polyethylene-styrene) resin, AES (acrylonitrile-EPDM-styrene) resin, high impact polystyrene (butadiene-styrene) ) resin, etc. Next, the copolymer of component (B) used in the present invention comprises an olefin monomer, a fatty acid vinyl ester monomer, and in some cases, these two and a vinyl copolymerizable with these monomers. It is a copolymer of monomers, and the olefin monomers mentioned here include ethylene, propylene, 1-butene, 2-butene, isobutylene, cyclopentene, cyclohexene, norbornene, and fatty acid vinyl ester monomers. Examples of vinyl monomers include vinyl formate, vinyl acetate, vinyl butyrate, vinyl trimethyl acetate, vinyl chloroacetate, etc. Other vinyl monomers that can be copolymerized with these monomers include styrene, α-methyl Styrene, vinyltoluene, chlorstyrene, dichlorostyrene, t-butylstyrene, cyanostyrene, aminostyrene, hydroxystyrene,
Styrenic monomers such as chloromethylstyrene, acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, 2-hydroxyethyl (meth)acrylic monomers such as acrylate, allyl acrylate, and glycidyl methacrylate; halogenated oleic monomers such as vinyl chloride and vinylidene chloride; vinyl ether monomers such as methyl vinyl ether, ethyl vinyl ether, and phenyl vinyl ether; and methyl vinyl Ketones, vinyl ketone monomers such as phenyl vinyl ketone, acrylamide,
Acrylamide monomers such as methacrylamide,
Examples include vinylpyridine and N-vinylcarbazole. Furthermore, polyfunctional vinyl monomers can be used in combination with the above combinations, if necessary. Examples of the polyfunctional vinyl monomer include ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, propylene glycol dimethacrylate, triallyl cyanurate, triallyl isocyanurate, and trimethylolpropane trimethacrylate. Examples include methacrylate, allyl acrylate, allyl methacrylate, and divinylbenzene. Component (B) of the present invention is produced by an emulsion polymerization method. There are no particular restrictions on the surfactant used in the emulsion polymerization of component (B), and anionic, cationic, nonionic, and amphoteric surfactants can be used alone or in combination, but they can help maintain emulsion stability during polymerization, foaming, etc. In order to suppress the phenomenon, it is preferable to use the nonionic high molecular weight surfactant in an amount of 5% by weight or more, preferably 20% by weight or more of the total amount of surfactant used. However, the nonionic high molecular weight surfactants mentioned here include polypropylene glycol ethylene oxide adducts, higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, fatty acid amine ethylene oxide adducts, polyvinyl alcohol, polyhydric alcohol higher fatty acid ester, etc. The copolymer of component (B) used in the present invention must have a gel content of less than 50% by weight. However, the gel content referred to here is determined by the following method. That is, 1 g of polymer is added to 100 g of methyl ethyl ketone and stirred vigorously at room temperature for 6 hours. This material is centrifuged at 15,000 rpm for 1 hour, and the dry weight of the precipitate is determined. The obtained dry weight is multiplied by 100 to obtain the gel content (% by weight). If component (B) is a copolymer with a gel content of 50% by weight or more, (A) in a solid or molten state
This is not preferable because the impact strength and tensile strength of the resin obtained by mixing the component resin and the component (B) in a latex state decrease. In addition, the copolymer of component (B) used in the present invention is
The solubility parameter must be in the range of 8.8 to 9.7 (cal/cc) ^1/2 . However, the solubility parameter here uses the solubility parameter value described in "Polymer Handbook" published by John Wiley & Sons, and the solubility parameter δ _T of the copolymer is the solubility parameter value for the copolymer consisting of m types of vinyl monomers. It is calculated by formula (1) from the solubility parameter Δn of the homopolymer of the individual vinyl monomers constituting it and its weight fraction Wn. Equation (1) δ _T = _n 〓 ⁿ⁼¹ δnWn/ _n 〓 ⁿ⁼¹ Wn [(cal/cc) ^1/2 ] For example, the solubility parameters of polyethylene, polyvinyl acetate, and polybutyl acrylate are 8.1, 9.4, and 8.8, respectively. So, 15% by weight of ethylene, 70% by weight of vinyl acetate, 15% by weight of butyl acrylate
The solubility parameter δ _T of the copolymer consisting of is 9.1
It is calculated as follows. If the solubility parameter of component (B) deviates from the above range, the impact strength, tensile strength and Environmental stress cracking resistance decreases, which is undesirable. As mentioned above, the gel content and solubility parameter of the copolymer of component (B) are limited, but the composition ratio of the copolymer is arbitrary within the range that satisfies the above limitations. In the present invention, 100 parts by weight of component (A) resin and 0.5 to 40 parts by weight, preferably 2 to 30 parts by weight of component (B) copolymer are mixed; The amount
If the amount is less than 0.5 parts by weight, the effect of improving the environmental stress cracking resistance of the resin obtained by mixing with component (A) will not be sufficient, and if it exceeds 40 parts by weight, the effect will not only be saturated, but also the rigidity decreases, which is not desirable. Furthermore, the copolymer used as component (B) is a copolymer of an olefin monomer and a fatty acid vinyl ester monomer, and a copolymer of a vinyl monomer copolymerizable with the above two monomers. and a mixture of the above two types of copolymers. Component (B) of the present invention is a solid obtained by drying a latex produced by an emulsion polymerization method without going through a precipitation step. The method of drying the latex without going through a precipitation step is not particularly limited, and conventional techniques such as spray drying and freeze drying can be applied, but spray drying is particularly preferred. Spray drying can be performed by feeding the latex into a spray dryer. Spray dryers are classified into rotating disk type, two-fluid nozzle type, pressure nozzle type, etc. depending on the atomization method.Also, depending on the hot air method,
Although it is classified into a parallel flow type, a countercurrent type, a parallel and countercurrent type (mixed type), etc., the present invention is not limited to these types. In order to prevent the fatty acid vinyl ester polymer solid obtained by spray drying from sticking, it is possible to add an anti-stick agent during spray drying. As an anti-stick agent, calcium carbonate, calcium sulfate, sulfuric acid, etc. Inorganic substances such as barium, aluminum hydroxide, calcium silicate, silica, talc, clay, magnesium oxide, zinc oxide, calcium stearate, magnesium stearate, barium stearate, zinc stearate, stearic acid, stearyl alcohol, stearic acid amide , higher fatty acids and their derivatives such as methylene bis stearylamide and ethylene bis stearyl amide, thermoplastic resin powders such as polypropylene, polyvinyl chloride, polystyrene, AS resin, ABS resin, polyvinyl alcohol, polyamide, polyester, phenolic resin, urea resin There are thermosetting resin powders such as In the present invention, component (A) and component (B) are mixed, and component (A) to be mixed can be in any of an emulsified state, a solution state, or a solid state. When component (A) is solid, mix component (A) and component (B) using a Henschel mixer, tumbler, super mixer,
After mixing using a mixing device such as a ribbon blender or a V-type mixer, it is mixed using a Banbury mixer, Inchinsib mixer, Miwastruder, Co-kneader, etc.
It can be supplied to a melt kneading device such as an Ewastruder or a roll to form a composition. Furthermore, it is also possible to prepare a composition by directly supplying component (A) and component (B) to a melt-kneading device. Furthermore, the thermoplastic resin composition of the present invention may contain pigments, dyes, stabilizers, dispersants, reinforcing materials, fillers, weathering agents, antistatic agents, foaming agents, lubricants, and the like. (Example) The present invention will be further explained below with reference to Examples, and all parts and percentages described in the Examples are expressed on a weight basis. Reference Example Spray drying of component (B) An ethylene-vinyl acetate copolymer latex consisting of 15% ethylene and 85% vinyl acetate was spray-dried by supplying it to a co-current spray dryer equipped with a rotating disk type atomizer. Summer. The drying device was cylindrical with a diameter of 2.5 m and a height of 2.5 m, and air was used as the hot air. The volume of hot air is ^700m3 /hour,
The inlet temperature of the hot air was 100°C, and the outlet temperature was 50-55°C. Using fine silica powder as an anti-stick agent,
It was sprayed from near the top of the tower at a ratio of 5% to the polymer. The ethylene-vinyl acetate copolymer solid recovered from the apparatus had a water content of 0.75% and was in powder form. In addition, the gel content of the copolymer is 18
%, and the solubility parameter calculated by formula (1) was 9.2 (Cal/cc) ^1/2 . Using the same spray dryer, Table 2B-2
- Spray drying of B-9 was carried out. Example 1 Component (A) shown in Table 1 (solid) and component (B) shown in Table 2 (solid) were charged into a Henschel mixer in the ratio shown in Table 3, and further 2 parts of ethylene bisstearylamide and TNP ( 0.2 part of phosphorus stabilizer) was added and mixed. Contents: VC manufactured by Chuo Kikai Seisakusho Co., Ltd.
-40 (vented single-screw extruder) and melt-kneaded to obtain pellets. Molded products were made from the obtained pellets and their physical properties were evaluated, and the results are shown in Table 3. In Table 3, Experiments Nos. 1 to 5 show the effect of the amount of component (B) added, Experiments Nos. 6 to 10 show the effect of the type of component (B), and Experiments Nos. 11 to 14 show the effect of the amount of component (B) added. A) Shows the influence of the type of ingredients. As is clear from Table 3, the compositions in any combination have good physical properties and thermal stability. Comparative example 1 (B) as component (B-5), (B-8), (B-9)
A molded article was prepared in the same manner as in Example 1, except that the following was used, and the physical properties were evaluated. The results are shown in Table 4, Experiment No.
Shown in 15, 16, and 17. Comparative Example 2 (A-1) 125 parts of latex (latex weight,
30% solid content) and 18 parts of latex (B-1) (latex weight, solid content 55%) were mixed in a latex state, and 0.35 part of 35% hydrochloric acid and 3.7 parts of calcium chloride were added and heated at 93°C. A slurry was obtained by stirring for 5 minutes. The wet powder obtained by dehydrating this slurry contains 46% water (A-
1) The moisture content was higher than that of wet powder, which was 21%, when only latex was precipitated under the same precipitation conditions. After drying, the wet powder was mixed with 62.5 parts of (A-6), 2.0 parts of ethylene bisstearoide, and 0.2 parts of TNP using a Henschel mixer, and pelletized using a single screw extruder. A molded article was made from the obtained pellets and its physical properties were evaluated, and the results are shown in Table 4, Experiment No. 18. In addition, when quantifying calcium chloride in the dry powder obtained by precipitating only the latex (A-1),
It was 660ppm, but (A-1) latex and (B
-1) Calcium chloride in the dry powder obtained by precipitating the latex mixture was quantified and found to be 5300 ppm. Comparative Example 3 10 parts of the (B) component solid obtained by adding a boric acid aqueous solution to the (B) component latex in Table 2 (B-1) to precipitate a polymer and drying it, 37.5 parts of (A-1), (A-6) 62.5
part, 2.0 parts of ethylene bisstearamide, 0.2 parts of TNP
and pelletized using a single-screw extruder. A molded article was made from the obtained pellets and its physical properties were evaluated, and the results are shown in Table 4, Experiment No. 19. Comparative Example 4 37.5 parts of (A-1), (A-6) as component (A)
Pellets were obtained in the same manner as in Example 1 except that 62.5 parts of the pellet and 45 parts of (B-1) were used as the component (B). Molded products were made from the obtained pellets and their physical properties were evaluated, and the results are shown in Table 4, Experiment No. 20. Comparative Example 5 Table 4 Experiment No. 21 shows the physical property evaluation results for component (A) only.
Shown in 22, 23, and 24. In these tests, all physical property measurements were obtained by the following methods. (1) Tensile yield point…ASTM D-638 (2) Izot impact strength…ASTM D-256 (3) Thermal stability test method Resin was placed inside the cylinder of a 2-ounce injection molding machine for 10 minutes at a cylinder temperature of 250°C. After residence, injection molding was performed, and the whiteness of the third shot molded product (50 x 80 x 3 mm flat plate) was _determined by COLOR AND COLOR manufactured by Nippon Gyoki Kogyo Co., Ltd.
DIFFERENCE METER MODEL ND−
Measure using 101DC. In addition, the whiteness W ₀ of a molded product injected without performing a residence operation using an injection molding machine under the same conditions is measured. Whiteness change rate WD
= (W ₀ - W ₁₅ )/W ₀ ×100 is determined, and WD<10 is evaluated as A, 10WD<20 as B, and WD〓20 as C. With a resin of WD 20, even if the molded product is injected without performing a dwell operation, it is not preferable because slight differences in molding temperature will cause a difference in W ₀ of the molded product. (4) Environmental stress cracking test method JIS K7113 No. 1 test piece was given a 50 mm sag, fixed in a jig, and glacial acetic acid (ESCR-AC) or ethylene glycol monoethyl ether (ESCR-EG) was applied. The time required to break when applied and left at 23°C is expressed in minutes.

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[Table] (Effects of the Invention) As explained above, the present invention provides rubber-containing styrenic resin (A) and fatty acid vinyl ester copolymer.
(B), and according to the composition of the present invention, there is no need to precipitate the (B) component latex by adding a precipitating agent, which not only simplifies and saves energy in the manufacturing process. Since the amount of precipitating agent remaining in the final composition can be kept to a minimum, the thermal stability of the final composition is improved. By limiting the gel content and solubility parameters of the component (B) copolymer to the above range, it has excellent environmental stress cracking resistance and also has excellent thermal stability. ,
It can be suitably used in areas that may come into contact with chemicals such as hydrocarbons, and considering that conventional rubber-containing styrenic resins have frequently caused environmental stress cracking when used in these areas. The industrial value is enormous.

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a rubber-containing styrenic resin; (B) a copolymer of an olefin monomer and a fatty acid vinyl ester monomer and/or the above two monomers; Copolymer with copolymerizable vinyl monomer (hereinafter referred to as fatty acid vinyl ester polymer)
In the composition of 0.5 to 40 parts by weight, the fatty acid vinyl ester polymer is a solid obtained by drying a latex produced by an emulsion polymerization method without going through a precipitation process, and its gel content is is less than 50% by weight, and its solubility parameter is 8.8 to 9.7 (cal/cc) ^1/2 .