JPS6361967B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a partially crosslinked thermoplastic elastomer composition containing liquid polar rubber and having excellent moldability, mechanical strength, and paintability. (Prior art and its problems) Recently, thermoplastic elastomers with excellent paintability have been developed such as polyolefin resins such as polypropylene and polyethylene, copolymer rubbers made of ethylene-propylene-non-component diene or ethylene-propylene-non-component diene, etc. A partially crosslinked thermoplastic elastomer composition consisting of a polyolefin rubber and a vinyl acetate-ethylene copolymer was disclosed in Japanese Patent Application Laid-open No. 1973-
Suggested by 145553. However, such compositions still have insufficient elasticity and paintability when the vinyl acetate-ethylene copolymer used has a low vinyl acetate content containing crystalline moieties formed by ethylene chains; When the copolymer has a high vinyl acetate content, the copolymer and the polyolefin resin have poor compatibility, and therefore do not have satisfactory moldability and mechanical strength. The inventors of the present invention have made extensive studies to improve these drawbacks, and have found that by mixing liquid polar rubber with polyolefin resin and polyolefin rubber and partially crosslinking the mixture, moldability, mechanical strength, paintability, etc. can be improved. It has been discovered that an excellent composition can be obtained, leading to the present invention. (Means for solving the problem) That is, the present invention provides (A) polyolefin resin 10 to
1 to 20 parts by weight of (D) liquid polar rubber to a total of 100 parts by weight of a mixture consisting of 50% by weight, (B) 50 to 70% by weight of polyolefin rubber, and 5 to 30% by weight of (C) vinyl acetate-ethylene copolymer rubber. The object of the present invention is to provide a thermoplastic elastomer composition characterized in that it contains part by weight and is partially crosslinked. Although the details of the excellent physical properties of the composition of the present invention are unknown, the liquid polar rubber is superior to polyolefin resins, polyolefin rubbers, vinyl acetate-ethylene copolymer rubber (hereinafter referred to as VAE rubber), etc. It is thought that it has a suitable affinity for these materials, promotes miscibility between these raw materials, and improves crosslinking properties, moldability, coating properties, etc. The liquid polar rubber in the present invention is a polymer whose main component is a diene monomer and has a number average molecular weight of 500 to 10,000, with carboxyl groups, hydroxyl groups, mercapto groups, halogen atoms, amino groups, epoxy groups, etc. in the molecule. It has a polar group and an unsaturated bond,
For example, poly 1,2-butadiene, poly 1,4-butadiene, polyisoprene, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, butadiene-isoprene copolymer, butadiene-pentadiene having such polar groups. Examples include copolymers, but poly-1,2-butadiene-based polar rubber is particularly preferred from the viewpoint of heat resistance and weather resistance. Among these, poly-1,2-butadiene having a hydroxyl group is particularly excellent in improving properties such as mechanical strength of the composition of the present invention. The amount of these liquid polar rubbers is usually a total of 100 parts by weight of olefin resin, olefin rubber, and VAE rubber (hereinafter, parts by weight are abbreviated as parts).
1 to 20 parts, preferably 5 to 10 parts.
If the amount exceeds 20 parts, the heat resistance of the composition, that is, discoloration when heated, and weather resistance will deteriorate significantly, and if it is less than 1 part, the effects of the present invention will be significantly reduced, which is inappropriate. . The polyolefin resin used in the present invention is crystalline, and examples include α-olefin homopolymers such as polyethylene, polypropylene, polybutene, and polypentene, and propylene copolymers containing a small amount of ethylene. In terms of properties (deformation resistance during heating and pressurization), those with particularly high crystallinity are preferred. Among others, processability, heat resistance,
Crystalline polypropylene is particularly preferred from the economic point of view. The amount of the polyolefin resin to be used is appropriately selected depending on the desired thermoplasticity and hardness of the composition of the present invention. 10 to 50% by weight of resin, polyolefin rubber, and VAE rubber)
(Hereinafter, % by weight is abbreviated as %), particularly preferably 15 to 40%. The polyolefin rubber used in the present invention is non-crystalline and does not contain vinyl acetate as a constituent. For example, it is made of aliphatic monoolefin such as ethylene, propylene, butylene, isobutylene, etc., or it is further composed of ethylidenenor. It is a rubbery copolymer made by adding a non-covalent diene such as bornene dicyclopentadiene. Particularly suitable are ethylene-propylene binary copolymer rubber and ethylene-propylene-non-coterminous diene ternary copolymer rubber. The amount of such polyolefin rubber used is usually at least 30% of the solid polymer, preferably 50 to 70%, within a range that provides rubber elasticity to the composition. Further, the VAE rubber used in the present invention is a sufficiently amorphous rubbery copolymer mainly composed of vinyl acetate and ethylene, and the weight ratio of vinyl acetate/ethylene is usually 40/60 to 85/15. Preferably 50/50 to 70/30
It consists of The amount of VAE rubber to be used is at least 5% of the solid polymer in order to achieve the effects sought by the present invention, and if it exceeds 30%, low temperature embrittlement will deteriorate, which is not preferred. The composition of the present invention is partially crosslinked, and the partial crosslinking is achieved by using polyolefin rubber and/or
Alternatively, customary crosslinking agents for VAE rubber are added to the composition. Examples of such crosslinking agents include 1,3-bis(tert-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,
2-bis(tert-butylperoxy)butane,
1,1-bis(tertiary butylperoxy)-3,
3,5-trimethylcyclohexene, 2,5-dimethyl-2,5-di(tertiary butylperoxy)
Examples include hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, and the like. The amount used is usually based on the solid polymer
It is 0.05 to 1 part, preferably 0.1 to 0.6 part. Furthermore, when the composition of the present invention is partially crosslinked, a crosslinking aid may be used in combination with the crosslinking agent. Examples of such crosslinking aids include triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, trimethylolpropane triacrylate, polyalkylene glycol dimethacrylate, divinylbenzene, m-phenylene bismaleimide, p-quinone dioxime, poly Examples include 1,2-butadiene. The appropriate amount of the crosslinking aid used is 1 to 5 parts per 1 part of the crosslinking agent. These crosslinking aids exhibit the effect of improving the permanent set properties of the composition of the present invention when used in combination with the liquid polar rubber. Furthermore, when partially crosslinking the composition of the present invention,
This can be done by adding a crosslinking promoter. Such crosslinking accelerators include various polyamines and their derivatives, ammonium salts and alkali metal salts of organic carboxylic acids, metal oxides, etc. Specifically, triethylene-tetramine, hexamethylenetetramine, hexamethylene diamine carbamate,
Examples include ammonium benzoate, sodium stearate, potassium stearate, zinc oxide, magnesium oxide, lead dioxide, and the like. The appropriate amount to be used is 0.5 to 10 parts per 1 part of the crosslinking agent. Partial crosslinking of the composition of the present invention can be carried out, for example, by kneading a predetermined mixture at a temperature equal to or higher than the melting point of the polyolefin resin using a heating kneading device such as a roll, internal mixer, or extruder, and then adding a crosslinking agent. and do it. The temperature and time at this time are appropriately selected depending on the capacity of the kneading equipment, but usually about 150~
Approximately 1 to 10 minutes at 230°C is appropriate. Incidentally, a radical remover can be added during crosslinking in order to appropriately stop the progress of crosslinking. Examples of such removing agents include known antioxidants such as amine-based, phenol-based, sulfide-based, phenylalkane-based, and phosphite-based antioxidants. Further, partial crosslinking of the composition of the present invention can also be carried out by irradiation with radiation. Therefore, the composition of the present invention usually contains 30 to 80% by weight of the total amount of polyolefin rubber, VAE rubber, and liquid polar rubber as insoluble matter when boiled in Tetralin solvent at 180°C for 4 hours. %, preferably 40 to 70% by weight. Incidentally, the inorganic filler was not included in the insoluble matter, and the measurement was carried out using 200 ml of tetralin per 1 g of the partially crosslinked resin composition, and was passed through a 200-mesh wire mesh. The composition of the present invention may contain conventional rubber and plastic compounding agents, such as fillers, process oils, plasticizers, lubricants, colorants, stabilizers, etc., as required. The partially crosslinked composition of the present invention thus obtained is particularly excellent in moldability, paintability, and strength and elongation, and is particularly useful for exterior cushioning parts for automobiles, electric wire and cable covering materials, and the like. Next, the effects of the present invention will be explained based on examples. Examples 1 to 6 and Comparative Example 1 The surface temperature of two 6" rolls of oil bath circulation type was set to 170
℃, ethylene-propylene copolymer rubber,
After kneading the predetermined amounts of vinyl acetate-ethylene copolymer rubber, liquid polar rubber, and polypropylene as shown in Table 1 for 5 minutes, 1.5 parts of peroxide (purity 40%) was added, and the kneading was continued for 5 minutes. After continuing for 1 minute, 1 part of trinonylphenyl phosphite was added as a radical terminator, and after kneading for another 2 minutes, the mixture was taken out in the form of a sheet. Incidentally, Comparative Example 1 is the case where the liquid polar rubber was not blended in the above-mentioned Examples. As shown in the results of the molding test, normal physical properties test, and paint adhesion test in Table 1, the composition of the present invention containing liquid polar rubber has far superior normal physical properties compared to Comparative Example 1. Improvements were also observed in molding processability and paint adhesion. In addition, the above-mentioned test materials and test methods are as follows. (a) Polypropylene: Mitsubishi Noblen MA-4 general-purpose grade; MI (ASTM D-1238) 5, specific gravity (ASTM D-792) 0.91; manufactured by Mitsubishi Yuka Co., Ltd. (b) Ethylene-propylene copolymer rubber: JSR-
EPO7P; Mooney viscosity ML ₁₊₄ (100℃) 70, ethylene content 73%; manufactured by Japan Synthetic Rubber Co., Ltd. (c) Vinyl acetate-ethylene copolymer rubber: Evathrene 310P; Mooney viscosity ML ₁₊₄ (100℃) 55, vinyl acetate content 70%; manufactured by Dainippon Ink and Chemicals Co., Ltd. (d) Liquid polar rubber (1): G-1000; α, ω-polybutadiene glycol, n = 1300, 1, 2 bonds = polymer chain Approximately 90%; manufactured by Nippon Soda Co., Ltd. (2): C-1000 α, ω-polybutadiene dicarboxylic acid, n = 1300, 1,2 bonds = approximately 90% of the polymer chain; manufactured by Nippon Soda Co., Ltd. (3) :BF-1000 n=1000, 1,2 bond; epoxidized product of butadiene homopolymer with about 90% polymer chain, oxirane oxygen 7.5-8.0%;
Manufactured by Adeka Argus Co., Ltd. (4): Ep-LCB-30; Partially epoxidized poly 1,
4-Butadiene, n=1700, oxirane oxygen 6.2; manufactured by Nippon Zeon Co., Ltd. (e) Peroxide (purity 40%): Percadox 14/40C; 1,3-bis(tert-butylperoxyisopropyl)benzene Product containing 40% of
mm and kneaded 100g of specimen for 5 minutes.
Difficulty in turning, rotation of the pool, difficulty in taking off the sheet, smoothness of the formed sheet, etc. were comprehensively evaluated and rated as ◎: excellent, ○: good, and △: slightly poor. (G) Press formability: 85 g of the rolled sheet was filled into a 2 mm x 150 mm x 200 mm flat mold, and after preheating at 200°C for 5 minutes using a press with a total pressure of 37 tons, the sheet was pressed under water cooling ( After 5 minutes (26 tons), the molded plate was taken out, and the molded plate was observed for difficulty in molding and surface properties, and evaluated in the same manner as the roll processability. (H) Extrusion moldability Molding machine: 30mmφ extruder; manufactured by Tanabe Kikai Co., Ltd. Molding temperature: C ₁ 150℃, C ₂ 190℃, die 180℃ Screw rotation speed: 30r.pm, L/D = 22, compression Ratio 2.5, use of a ribbon die, take-up properties of the formed strand, and surface smoothness were observed and evaluated in the same manner as roll processability. (li) Normal state physical property test: A sample was taken from the press-formed plate and measured in accordance with JIS K-6301. However, the spring hardness was set to Shore A and the pulling speed was 200 mm/min. (NU) Paint adhesion (checkerboard test) A two-component acrylic urethane paint was applied onto the press-formed plate using a 0.15 mm bar coater.
Dry for 30 minutes at 70°C, then 23°C, relative humidity 65
After leaving it in a room for 24 hours, use a razor blade to create 100 1mm square grids on the painted surface, stick cellophane tape on top of it, and peel it off.
At that time, the percentage of the number of stitches remaining on the painted surface without peeling is displayed, and is considered as the degree of adhesion of the paint to the surface to which it is applied. That is, 0/100 indicates complete peeling and the poorest paint adhesion, and 100/100 indicates complete adhesion and the best paint adhesion. Examples 7 to 9, Comparative Examples 2 to 4 Each composition was obtained in the same manner as in the Examples using the raw materials shown in Table 2. However, Example 9 and Comparative Example 4
In this case, calcium carbonate was mixed as a filler during kneading before adding peroxide. The physical properties of each composition are shown in Table 2. As is clear from the table, the addition of liquid polar rubber significantly improves the normal physical properties and also improves moldability and paint adhesion.

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Claims (1)

[Claims] 1 (A) 10 to 50% by weight of polyolefin resin, (B) 50 to 70% by weight of polyolefin rubber, (C) 5 to 30% by weight of vinyl acetate-ethylene copolymer rubber
1. A thermoplastic elastomer composition comprising 1 to 20 parts by weight of (D) liquid polar rubber in a total of 100 parts by weight of a mixture consisting of (D), which is partially crosslinked.