JPH041784B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a resin composition having excellent stress concentration resistance. More specifically, the present invention relates to an impact-resistant and weather-resistant resin composition having excellent stress concentration resistance, which is made by blending a polyester compound consisting of a fatty acid and a polyhydric alcohol with a non-diene rubber-reinforced resin. (Prior art) A polymer obtained by graft polymerizing styrene and acrylonitrile to a non-diene rubber such as ethylene-propylene rubber, or a non-diene polymer composed of such a graft polymer and a styrene-acrylonitrile copolymer. Rubber-reinforced resins (AES resin, ACS resin, AAS resin) have excellent impact resistance and weather resistance, and are expected to be used in a wide range of fields including automobile parts and light electrical parts. (Problem to be solved by the invention) However, these rubber reinforced resins have fewer craft active sites in the rubber component than conjugated diene rubber reinforced resins such as so-called ABS resins, making it difficult to control graft polymerization. Ideal graft structure (grafting ratio, number and length of graft chains, etc.)
Due to reasons such as difficulty in obtaining the desired particle size and dispersion form of the rubber or graft depending on the polymerization method, even if the test piece has sufficient elongation during a tensile test in which a uniform stress is applied to the test piece, The breaking strain in the bending test where the maximum stress is applied to the center of the is small,
Particularly when stress concentration occurs in a molded product, it has the disadvantage of being susceptible to cracking even at a very small amount of strain. Furthermore, to give specific examples of these phenomena, for example, the ribs and bosses of molded products tend to break, the tabs tend to break when mated with other parts, and stress is concentrated in mounting holes etc. during product vibration tests. For example, cracks may occur in a short period of time where the (Means for Solving the Problems) The present inventors have discovered that non-diene rubber reinforced resins have not only excellent impact resistance and weather resistance, but also other useful properties such as steel properties, heat resistance, and moldability. The present invention was achieved as a result of intensive research aimed at solving these problems without sacrificing the above. That is, the present invention provides a rubber-reinforced resin obtained by polymerizing one or more compounds selected from the group consisting of an aromatic vinyl compound, a vinyl cyanide compound, and an unsaturated carboxylic acid alkyl ester compound in the presence of a non-diene rubber. Stress concentration resistance characterized by blending 0.05 to 5 parts by weight of a polyester compound with a molecular weight of 700 to 2000, which is composed of a higher fatty acid with a fatty acid carbon number of 14 or more and a polyhydric alcohol, per 100 parts by weight. It is a resin composition with excellent properties. The present invention will be explained in more detail below. Γ Rubber Reinforced Resin Non-diene rubber constituting the rubber reinforced resin used in the present invention includes ethylene-propylene copolymer, ethylene-propylene-non-conjugated diene containing non-conjugated dienes such as dicyclopentadiene and ethylidene norbornene. Copolymers, ethylene-vinyl acetate copolymers, acrylic acid alkyl ester polymers represented by polybutyl acrylate, chlorinated polyethylene, etc. can be mentioned, and one or more types can be used. Particularly preferred are ethylene-propylene copolymers and ethylene-propylene-nonconjugated diene copolymers. Examples of aromatic vinyl compounds include styrene, α
-Methylstyrene, dimethylstyrene, vinyltoluene, etc. can be mentioned, and one or more types can be used. Particularly preferred are styrene and α-methylstyrene. Examples of vinyl cyanide compounds include acrylonitrile, methacrylonitrile, etc., and one or more types can be used. Acrylonitrile is particularly preferred. Furthermore, examples of the unsaturated carboxylic acid alkyl ester compound include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, etc. Two or more types can be used. Particularly preferred is methyl methacrylate. The composition ratio of the non-diene rubber and the compound in the rubber reinforced resin is not particularly limited, but it is preferably 5-80% by weight of the non-conjugated diene-based rubber and 95-20% by weight of the compound. In addition, there is no particular restriction on the composition ratio of each compound in the compound subjected to polymerization, but 50 to 80% by weight of an aromatic vinyl compound and 50 to 80% by weight of a vinyl cyanide compound and/or an unsaturated carboxylic acid alkyl ester compound.
Preferably it is 20% by weight. Rubber-reinforced resins obtained by polymerizing one or more compounds carried from such compounds in the presence of non-diene rubber can be prepared using known polymerization methods such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, and obtained by their combination. Note that it is difficult to bond 100% of the compound onto non-diene rubber, and rubber reinforcing resins usually contain free (co)polymers. Also produced separately (co-) with polymers with high rubber content.
It may also be a rubber reinforced resin mixed with a polymer. Examples of these (co)polymers include polystyrene, polymethyl methacrylate, styrene-acrylonitrile copolymer, α-methylstyrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, etc. Rubber reinforced resin Obtained by the same polymerization method as . Γ Polyester Compound The polyester compound used in the present invention is
It is an esterification reaction or transesterification product of a higher fatty acid having 14 or more carbon atoms and a polyhydric alcohol, and as the fatty acid, one type or a mixture of two or more of saturated fatty acids and unsaturated fatty acids can be used. Examples of saturated fatty acids include palmitic acid, margaric acid, and stearic acid, and examples of unsaturated fatty acids include zomarinic acid and oleic acid. Furthermore, higher fatty acids containing hydroxyl groups, such as hydroxystearic acid and ricinoleic acid, can also be used. Examples of the polyhydric alcohol include trivalent to hexavalent alcohols, such as glycerin, erythritol, pentaerythritol, sorbitol, mannitol, etc., and one or more of them can be used. In particular, the tetrahydric alcohols erythritol and pentaerythritol are preferred. The molecular weight of the polyester compound in the present invention is 700 to 2000. If the molecular weight of the polyester compound is outside this range, the resin composition will have poor heat resistance, dispersibility during blending, and meltability, which is not preferred. Such a polyester compound can be processed by a known esterification reaction, such as a high temperature non-catalytic reaction at about 250°C,
It can be obtained by reaction in the presence of a tin chloride catalyst or the like at 200 to 230°C, or by transesterification of fats and oils using an alkaline catalyst. In addition, in these reactions, there may be unreacted alcoholic hydroxyl groups in the compound without 100% esterification, or unreacted fatty acids or polyhydric alcohols may remain depending on the degree of purification after the reaction. However, it is preferable to use a highly esterified compound and a product with as little residual unreacted material as possible. Γ Compounding The amount of the polyester compound added to the rubber reinforced resin is 0.05 to 5 parts by weight per 100 parts by weight of the rubber reinforced resin. If the blending amount of the polyester compound is outside the above range, the heat resistance and dispersibility of the resin composition during blending,
It is not preferred because it has poor meltability. Further, the blending can be carried out using a known mixing device such as a Banbury mixer or an extruder. Furthermore, when blending polyester compounds, not only known additives such as dyes and pigments, stabilizers, plasticizers, antistatic agents, ultraviolet absorbers, lubricants, fillers, and flame retardants, but also polycarbonates, polyacetals, polysulfones, etc. It is also possible to blend other polymers. The present invention will be explained below using Examples, but the present invention is not limited thereto. Examples and Comparative Examples Rubber reinforced resins (A to E) and polyester compounds were kneaded in a Banbury mixer to obtain resin compositions. Table 1 shows the formulation and properties of the resulting resin composition. The rubber reinforced resin used was obtained by the following method. Γ rubber reinforced resin A ethylene-propylene-ethylidene norbornene “EPDM” (iodine value 21, Mooney viscosity
75, propylene content 50% by weight) 120 parts by weight,
430 parts by weight of styrene and 200 parts by weight of acrylonitrile
Part by weight was dissolved in a mixed solution of 3000 parts by weight of n-hexane and 1500 parts by weight of ethylene dichloride, and after adding 3 parts by weight of benzoyl peroxide, polymerization was carried out at 67°C for 10 hours. Rubber reinforced resin A (grafting ratio 50%) was separated and recovered from the polymerization solution. Γ Rubber Reinforced Resin B Polymerization was carried out in the same manner as Rubber Reinforced Resin A except that 370 parts by weight of EPDM, 250 parts by weight of styrene and 130 parts by weight of acrylonitrile were used to obtain a polymer (grafting rate: 50% by weight). A styrene-acrylonitrile copolymer (weight ratio: 70/30, intrinsic viscosity 0.58) separately obtained by bulk-suspension polymerization was mixed with the obtained polymer to obtain a rubber reinforced resin with a rubber content of approximately 20%. I got a B. ΓRubber reinforced resin C α-methylstyrene separately obtained by emulsion polymerization method is added to the polymer used for rubber reinforced resin B.
Acrylonitrile copolymer (weight ratio: 70/30,
(intrinsic viscosity: 0.48) to obtain a rubber reinforced resin C having a rubber content of about 20%. Γ Rubber Reinforced Resin D The polymer used for Rubber Reinforced Resin B was mixed with polymethyl methacrylate "Sumipetx B-LG" manufactured by Sumitomo Chemical Co., Ltd. to obtain Rubber Reinforced Resin D having a rubber content of about 20%. Γ Rubber Reinforced Resin E 450 parts by weight of water, 0.35 parts by weight of a suspension dispersant (hydroxyethyl cellulose), ethylene-propylene-ethylidene norbornene "EPDM" ground to an average of 3 mm squares (iodine value 8.5, Mooney viscosity 61, propylene content 43% by weight) 40 parts by weight,
140 parts by weight of styrene, 60 parts by weight of acrylonitrile, and 2.3 parts by weight of t-butyl peroxide as an initiator were added, stirred at 26°C for 1 hour, and then further heated to 110°C to carry out polymerization. Thereafter, the reaction product was cooled to room temperature, filtered and dried to obtain rubber reinforced resin E (grafting ratio 50%).

【table】

[Table] (Effects of the invention) As described above, when improving the stress concentration resistance (exemplified by bending strain at break in Examples and Comparative Examples) of non-diene rubber-reinforced resin, By incorporating a polyester compound, it was possible to exhibit significantly superior effects compared to conventional compositions without sacrificing other useful properties.

Claims (1)

[Claims] 1. Rubber reinforcement obtained by polymerizing one or more compounds selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds, and unsaturated carboxylic acid alkyl ester compounds in the presence of a non-diene rubber. Per 100 parts by weight of resin, the molecular weight consists of higher fatty acids with fatty acid carbon numbers of 14 or more and polyhydric alcohols.
A resin composition having excellent stress concentration resistance, characterized in that it contains 0.05 to 5 parts by weight of a polyester compound having a molecular weight of 700 to 2,000. 2. The resin composition according to claim 1, wherein the polyhydric alcohol is a tetrahydric alcohol.