JPH051824B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a thermoplastic resin composition mainly consisting of a polyamide resin, polystyrene or a styrene-based copolymer, and an inorganic filler, which gives molded articles with improved mechanical strength. (Prior Art) It is known to obtain a resin composition that provides a molded article with improved oil resistance and heat resistance by blending polystyrene or a copolymer mainly composed of styrene with a polyamide resin. However, molded articles made from this resin composition are insufficient in mechanical strength and dimensional accuracy. Although dimensional accuracy is slightly improved by blending maleic anhydride-modified polystyrene with polyamide, mechanical strength is still insufficient. In order to eliminate these drawbacks, it is known to add inorganic fillers such as glass fibers, but this results in the drawback that the molded product becomes brittle. (Problems to be Solved by the Invention) The present invention provides a resin composition that does not have the above-mentioned drawbacks and provides a molded article with significantly improved mechanical strength. (Means for Solving the Problems) The present inventor added a styrene thermoplastic elastomer copolymer having groups such as carboxyl groups in the elastomer portion to a composition comprising a polyamide resin, a styrene polymer, and an inorganic filler. The present invention was completed based on the discovery that the mechanical strength of a molded article can be significantly improved by adding a small amount of it. That is, the present invention provides 100 parts by weight of a resin composition consisting of (a) 50-95% by weight of a polyamide resin, (b) 5-50% by weight of a styrene polymer, (c) 5-100 parts by weight of an inorganic filler, and (d) The elastomer portion of the styrene-based thermoplastic elastomer copolymer contains a carboxy group, an acid anhydride group, an acid amide group, an imide group, a carboxylic acid ester group, an epoxy group, an amino group, and a hydroxyl group. A thermoplastic resin composition containing 0.01 to 5 parts by weight of a styrenic thermoplastic elastomer copolymer having a group. In the present invention, the polyamide resin is a polymer containing -CONH- bonds in the repeating unit,
Typical examples are 4-nylon, 6-nylon,
6,6-nylon, 11-nylon, 12-nylon, 6,10-nylon, polyamide from terephthalic acid and trimethylhexamethylene diamine, polyamide from adipic acid and metaxylylene diamine, adipic acid and azelaic acid and 2, 2-
Examples include polyamides from bis(p-aminocyclohexyl)-propane, polyamides from terephthalic acid and 4,4'-diaminodicyclohexylmethane, and the like. The styrenic polymer used in the present invention is known per se and has the general formula (In the formula, R is hydrogen or an alkyl group having 1 to 4 carbon atoms, Z represents a substituent that is a halogen atom or an alkyl group having 1 to 4 carbon atoms, and p is 0
The polymer must contain at least 25% by weight of a repeating structural unit derived from a vinyl aromatic compound represented by Examples of such styrenic polymers include homopolymers of styrene or its derivatives, as well as polybutadiene, polyisoprene, butyl rubber, EPDM,
Styrenic polymers modified with natural or synthetic elastomeric materials, such as ethylene-propylene copolymers, natural rubber, epichlorohydrin;
Styrene-containing copolymers, such as styrene-acrylonitrile copolymers (SAN), styrene-methyl methacrylate copolymers, styrene-α-methylstyrene copolymers, styrene-vinyltoluene copolymers, styrene-butadiene copolymers , styrene-maleic anhydride copolymer, and styrene-acrylonitrile-butadiene copolymer (ABS). Preferred styrenic polymers for the present invention are homopolystyrene and ABS
It is. The weight of styrene polymer is 5% compared to the total weight of polyamide resin and styrene polymer.
Must be in the range ~50% by weight. This is 5
If the amount is less than % by weight, the intended effects of the addition of the styrenic polymer, which are reduction in water absorption and improvement in impact strength, will not be sufficiently achieved. On the other hand, if it exceeds 50% by weight, the inherent advantages of polyamide resin, such as chemical resistance and abrasion resistance, are lost. In the present invention, conventional inorganic fillers such as glass fibers, carbon fibers, metal fibers, fibers such as asbestos, calcium carbonate, talc, barium sulfate, and glass beads can be used. Particularly preferred are glass fiber and carbon fiber. The amount of the inorganic filler is 5 to 100 parts by weight based on the total of 100 parts by weight of the above-mentioned polyamide resin and styrene polymer. If this is less than 5 parts by weight,
The reinforcing effect is small, and on the other hand, if it exceeds 100 parts by weight, the molded product becomes brittle. In the present invention, the component (d) that increases the mechanical strength of the molded article when added in a small amount, that is, the elastomer part of the styrene thermoplastic elastomer copolymer,
In a styrenic thermoplastic elastomer copolymer having a group selected from the group consisting of a carboxyl group, an acid anhydride group, an acid amide group, an imide group, a carboxylic acid ester group, an epoxy group, an amino group, and a hydroxyl group, The plastic elastomer is a block copolymer of a diene rubber central block such as polybutadiene and a polyvinyl aromatic hydrocarbon end block such as polystyrene, or a hydrogenated product of such a block copolymer. The terminal block of this styrenic elastomer is, for example, styrene, α
- Vinyl aromatic hydrocarbon polymers consisting of methylstyrene, vinylstyrene, vinylxylene, ethylvinylxylene, vinylnaphthalene, etc., and mixtures thereof, and the terminal blocks may be the same or different polymers. Also good. The central block is, for example, a rubbery polymer consisting of butadiene, propylene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, etc., and mixtures thereof. Furthermore, the block copolymers can have either a linear sequence or a structure such as teleradial. Furthermore, at least one of the aliphatic double bonds of the styrenic thermoplastic elastomer is
A styrenic thermoplastic elastomer that is hydrogenated until 80%, preferably 90% or more of the bonds are saturated (that is, until the degree of unsaturation is reduced to 10% or less of the original degree of unsaturation) can also be used as a styrenic thermoplastic elastomer. The ratio and average molecular weight of the components of these block copolymers can vary over a wide range, but the molecular weight of the central block should be greater than the total molecular weight of the end blocks. For example, it is preferred to form a block copolymer from end blocks having an average molecular weight of about 4,000 to 115,000 and a central block having an average molecular weight of about 20,000 to 450,000. Approximately 8000 terminal blocks
Even more preferably, the central block has an average molecular weight of about 50,000 to 300,000. The terminal block preferably constitutes 2 to 33% by weight of the total block copolymer, more preferably 5 to 30% by weight. Preferred copolymers have a polybutadiene type central block and have 35 to 55% of butadiene carbon atoms, more preferably
It is formed from a copolymer with 40-50% vinyl side chains. Particularly preferred in the present invention is a styrenic thermoplastic elastomer in which the terminal block is homopolystyrene and the central block is polybutadiene, or a hydrogenated version thereof. In the component (d) used in the present invention, the elastomer portion of the styrenic thermoplastic elastomer copolymer as described above has a carboxy group, an acid anhydride group,
Acid amide group, imide group, carboxylic acid ester group,
Groups selected from the group consisting of epoxy groups, amino groups and hydroxyl groups, preferably carboxy groups and/or acid anhydride groups, are present. Further, the styrene moiety may contain the above groups or other groups such as an alkyl group or a halogen atom. Most preferably, a styrene-butadiene elastomer copolymer having a carboxy group in the butene moiety is used as component (d), such as commercially available Kraton DX-1300.
(Trademark: Shell) can be used. The amount of component (d) is from 0.01 to the weight of component (a) + (b).
It is 5 parts by weight. If this amount exceeds 5 parts by weight, the mechanical strength will deteriorate even more. If this amount is less than 0.01 part by weight, the effect of adding component (d) will not be achieved. The present invention will be further explained below with reference to Examples. Example A thermoplastic resin composition having the composition shown in Table 1 below was extruded into pellets at 290°C using a twin screw extruder equipped with a vacuum pent. This pellet-like resin was heated at a cylinder temperature of 250℃, an injection pressure of 800Kg/cm ² , and a mold temperature of 80℃.
A molded article was molded using an injection molding machine set at .degree. The molded body has tensile strength according to ASTM D-638.
Bending strength and bending elasticity were evaluated according to ASTM D-790. The results are shown in Table 1. From the table, it can be seen that the molded articles made using the composition of the present invention have excellent mechanical strength.

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【table】

Claims (1)

[Scope of Claims] 1 (c) 5 to 100 parts by weight of an inorganic filler per 100 parts by weight of a resin composition consisting of (a) 50 to 95% by weight of a polyamide resin (b) 5 to 50% by weight of a styrene polymer and (d) the elastomer portion of the styrene-based thermoplastic elastomer copolymer contains a group selected from the group consisting of a carboxy group, an acid anhydride group, an acid amide group, an imide group, a carboxylic acid ester group, an epoxy group, an amino group, and a hydroxyl group. A thermoplastic resin composition comprising 0.01 to 5 parts by weight of a styrenic thermoplastic elastomer copolymer having a group. 2. The thermoplastic resin composition according to claim 1, wherein the group of component (d) is selected from the group consisting of a carboxyl group and an acid anhydride group. 3. The thermoplastic resin composition according to claim 1, wherein component (d) is a styrene-butadiene elastomer copolymer having a carboxyl group and/or an acid anhydride group.