JPS6339019B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is made by adding a small amount of a specific non-diene rubbery polymer to a rubber-reinforced thermoplastic resin containing a graft copolymer obtained by graft copolymerizing a vinyl monomer mixture to ethylene-propylene rubber. This invention relates to a thermoplastic resin composition with excellent weather resistance and cold secondary processing properties. AES resin (terpolymer resin consisting of ethylene-propylene rubber, acrylonitrile, and styrene) and AEMS resin (quaternary copolymer resin consisting of ethylene-propylene rubber, acrylonitrile, styrene, and methyl methacrylate) are weather resistant. As a thermoplastic resin with excellent strength and impact resistance, it is often used in molded products, extrusion molded products, and other automotive parts and industrial products. However, when these molded products are subjected to secondary processing in cold conditions, whitening and stress cracks (cracks that appear on the appearance of the product, which are particularly likely to occur when they come into contact with chemicals) are likely to occur in the processed parts. , a decrease in mechanical strength, especially impact resistance and tensile strength, is observed. For this reason, molded products are generally processed by heating, but in this case, there are drawbacks such as the molded products shrinking or deforming due to heating, resulting in poor dimensional stability. Therefore, the present inventors have conducted intensive studies on methods to improve the whitening phenomenon and stress cracks that occur when cold bending and other secondary processing is performed on molded products without impairing the original properties of thermoplastic resins. As a result, the inventors have discovered that the above object can be achieved by adding a small amount of a specific non-diene rubbery polymer to a rubber-reinforced thermoplastic resin using ethylene-propylene rubber, and have arrived at the present invention. That is, the present invention provides a graft copolymer obtained by graft copolymerizing an aromatic vinyl compound, a vinyl cyanide compound, or a vinyl monomer mixture consisting of these and (meth)acrylic acid ester to ethylene-propylene rubber. At least one non-diene rubbery polymer selected from ethylene-propylene copolymer rubber, butyl rubber, and acrylic rubber is added to 100 parts by weight of the rubber-reinforced thermoplastic resin.
The present invention provides a thermoplastic resin composition in which 8 parts by weight of the above ingredients are added. The constituent components of the rubber-reinforced thermoplastic resin in the present invention are illustrated below. Ethylene-propylene rubber is a binary or ternary copolymer of ethylene and propylene or a non-conjugated diene. Non-conjugated dienes include dicyclopentadiene, ethylidene norbornene,
Examples include 1,4-hexadiene, and two or more of these may be used in combination. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, and vinyltoluene. Examples of vinyl cyanide compounds include acrylonitrile, methacrylonitrile, and chloroacrylonitrile. Further, the ester group of the (meth)acrylic acid ester includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and the like. More specific examples of the rubber-reinforced thermoplastic resin used in the present invention include ethylene-propylene copolymer or ethylene-propylene-nonconjugated diene terpolymer with styrene and/or α-
The so-called AES is a graft copolymer obtained by graft copolymerizing a mixture of methylstyrene and acrylonitrile, or a mixture of the thus obtained graft copolymer and a copolymer of styrene and/or α-methylstyrene and acrylonitrile. resin,
Also included are AEMS resins produced by adding methyl methacrylate to the above monomer components. The proportion of rubber component in rubber-reinforced thermoplastic resin is
Although not particularly limited, when the amount is about 5 to 30% by weight, impact resistance is high and the thermoplastic resin has a good balance. In the present invention, the non-diene rubbery polymer to be added and mixed with the rubber-reinforced thermoplastic resin includes ethylene-propylene copolymer rubbers such as ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, etc. , acrylic rubber and butyl rubber, and two or more of these can also be used in combination. The amount of the non-diene rubbery polymer added must be within a range that provides excellent mechanical properties of the rubber-reinforced thermoplastic resin, in particular impact resistance, heat resistance, and tensile strength. It is used in an amount of 2 to 8 parts by weight per 100 parts by weight of the resin. If it exceeds 8 parts by weight, mechanical properties will deteriorate, and if it is less than 2 parts by weight, the effects of the present invention cannot be obtained. There are no particular restrictions on the method of addition and mixing, but if the rubber-reinforced thermoplastic resin and non-diene rubbery polymer are in the form of an emulsion, a latex blend is best, or if both are in the form of a solution, they may be mixed in the form of a solution. All you have to do is process it afterwards. Generally, rubber-reinforced thermoplastic resins are often in the form of pellets or powders, and non-diene rubbery polymers are often in the form of lumps, so in that case, both can be mixed using a roll or Banbury kneader. . The mixture can be made into pellets, usually using a sheet cutter or an in-line screw extruder. Conventionally, molded products require industrially advanced technology and use complicated molds with slide cores, etc., resulting in high production costs.However, the resin composition of the present invention can be used to produce relatively simple products. Manufacturing costs are reduced because it is first molded in a mold and then subjected to cold secondary processing to form something similar to a molded product. In addition, molded products with irregular R-shapes, which are usually difficult to extrude, can be processed extremely easily by molding the resin composition of the present invention and then performing secondary processing in the cold. The resin composition of the invention is also extremely effective as a resin for molding used in automobiles and the like. The present invention will be specifically explained below using Examples. Example 1 75 parts by weight of a monomer mixture of styrene and acrylonitrile (weight ratio 70/30) was grafted onto 25 parts by weight of ethylene-propylene-nonconjugated diene rubber (JSR EP 22) by normal radical polymerization in the presence of a solvent. Polymerization was performed to obtain a graft copolymer (hereinafter referred to as AES). On the other hand, styrene and acrylonitrile (weight ratio 70/30) are polymerized by normal bulk suspension polymerization to create a copolymer (hereinafter referred to as AS).
was prepared separately. Both were pelletized separately using an extruder at a resin temperature of 200°C. Ethylene-propylene-nonconjugated diene rubber copolymer rubber (JSR EP 27) at the compounding ratio shown in Table 1.
was added and kneaded using a roll at 180°C for 3 minutes, and a 2 mm thick sheet was pulled out. The obtained sheet was pelletized using a sheet pelletizer. Feed each pellet to a screw-in injection molding machine,
A molded piece was obtained using a 1/8″ x 1″ x 5″ mold at a resin temperature of 220°C.This molded piece was tested using an ASTM No. 1 dumbbell and a 1/8″ x 1/2″ x 5″ test. A piece was cut out and tested for physical properties. The results are shown in Table 1 (injection molded products) and Table 2 (extrusion molded products).The test conditions were the test piece as it was and the test piece subjected to secondary processing (using an R-shaped jig) at room temperature. The test was performed on a molded product with a strain of 2%.
Tensile strength was measured according to ASTM D-638, and Izod impact strength was measured according to ASTM D-256 at room temperature. In addition to the above-mentioned physical properties, for extrusion molded products, the % strain of stress cracks under white kerosene was calculated from the cracking phenomenon after 24 hours of penetration using a 1/4 oval jig. Regarding weather resistance, test pieces were molded to a 2% strain through secondary processing and then irradiated for 200 hours and 500 hours using an accelerated weather resistance tester (Sunshine Weather-Ometer). Judgment was made based on the presence or absence of cracking on the irradiated surface.

【table】

[Table] From the results of Tables 1 and 2, JSR
It can be seen that the product to which EP27 (non-diene rubbery polymer) was added had very little reduction in strain after secondary processing of 2% strain, and was significantly superior to the data of the comparative example described below. Similarly, it can be seen that the composition of the present invention is also excellent in stress crack resistance to chemicals and weather resistance shown in Table 2. Example 2 In Experiment No. 3 of Example 1, various non-diene rubber polymers shown in Table 3 were used instead of the ethylene-propylene-nonconjugated diene copolymer rubber as the non-diene rubber polymer. Molded products were obtained by extrusion molding using the same blending method and molding conditions except that 5 parts by weight of each were added, and the molded products were evaluated. The results are shown in Table-3.

[Table] From the results in Table 3, the non-diene rubber polymers to which butyl rubber and acrylic rubber were added had better mechanical properties, stress crack resistance, and weather resistance than Experiment No. 3 in Table 1. Similar effects were observed. Comparative Example 1 Under the same molding conditions as in Example 1, evaluations similar to those shown in Tables 1 and 2 were conducted for products that did not contain JSR EP27 and those that added 1 part by weight and 9 parts by weight of JSR ED27. . The results are shown in Table-4 and Table-5.

【table】

[Table] From the results in Tables 4 and 5, the strain is 2% for those that do not contain JSR EP27 and those that have an additive amount of 1 part by weight.
It is clear that the mechanical strength after processing and the cracking phenomena of stress cracks and weather resistance are inferior. Further, when the amount added is 9 parts by weight (No. 4), the mechanical strength such as tensile strength, rigidity, heat resistance, etc. is decreased, and the inherent properties of the thermoplastic resin are deteriorated. Comparative Example 2 Under the same compounding method and molding conditions as in Example 2, 5 parts by weight of each of various rubbery polymers other than the present invention were added in place of the non-diene rubbery polymer specified in the present invention. I conducted an evaluation. The results are shown in Table-6. From the results shown in Table 6, when diene-based rubber is used, the mechanical strength and stress crack resistance of the 2% strain fabricated product, especially the weather resistance, are significantly lowered compared to those of the present invention.

[Table] Comparative Example 3 Experiment No. 8 in Table 7 uses polybutene with a molecular weight of 1200 instead of the ethylene-propylene-nonconjugated diene copolymer rubber in Experiment No. 3 of the example. No. 9 was carried out in the same manner as in Example 1 except that polybutene with a molecular weight of 18,000 was used. Table 7 shows the test results for the extruded product. Both Experiment Nos. 8 and 9 are outside the scope of the present invention, and the mechanical strength and stress crack resistance of the 2% strain secondary processed product are inferior to those of the present invention.

【table】

[Table] Comparative Example 4 Experiment No. 10 in Table 8 is an example using an ethylene-vinyl acetate copolymer, which has poor white kerosene stress crack resistance.

【table】

Claims (1)

[Claims] 1 Rubber-reinforced thermoplastic containing a graft copolymer obtained by graft copolymerizing an aromatic vinyl compound and a vinyl cyanide compound or a vinyl monomer mixture consisting of them and (meth)acrylic acid ester to ethylene-propylene rubber. 100 parts by weight of resin,
At least one selected from ethylene-propylene copolymer rubber, butyl rubber, and acrylic rubber
A thermoplastic resin composition containing 2 to 8 parts by weight of a non-diene rubbery polymer.