JP3414421B2 - Stabilized synthetic resin composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin composition having excellent moldability, excellent stability against heat and oxidation, and heat discoloration at the same time. . [0002] Synthetic resins are often degraded by the action of heat and oxygen during production, storage, processing or use, and their physical properties are often significantly reduced with phenomena such as discoloration and molecular weight reduction. Are known. For the purpose of preventing such phenomena, various phenol-based, phosphorus-based,
Sulfur-based antioxidants are used alone or in combination during the production and processing steps of synthetic resins. For example, 2,6-di-tert-butyl-p-cresol, stearyl-β- (3,5-di-tert-butyl-4-hydroxyphenol) propionate, tetrakis [methylene-3 (3 ′, 5'-di-t-butyl-
[4'-hydroxyphenyl) propionate] A phenolic antioxidant such as methane alone may be used alone, or these phenolic antioxidants and sulfur-based antioxidants such as dilaurylthiodipropionate and distearylthiodipropionate may be used. Or a method in which the above-mentioned phenolic antioxidant is used in combination with a phosphorus-based antioxidant such as triisodecyl phosphite or trinonylphenyl phosphite. Further, in order to improve moldability, especially mold releasability from a mold of a molding machine, metallic soaps are used during the production and processing steps of synthetic resins. For example, it is known to use metal soaps such as zinc stearate, calcium stearate, cadmium laurate, and barium naphthenate. However, these methods are not yet fully satisfactory in heat discoloration resistance. SUMMARY OF THE INVENTION The object of the present invention is to improve the moldability, the stability against heat and oxidation, and the heat discoloration by optimizing the combination of a sulfur compound, a phenol compound and a compound containing a metal. It is an object of the present invention to provide a stabilized synthetic resin composition having excellent properties at the same time. The present inventors have conducted various studies to solve these problems, and as a result, have found that a specific phenolic compound, a compound containing a specific metal, and a specific sulfur-based compound have been developed. By blending into a synthetic resin, it has extremely excellent moldability and heat and oxidation stability that cannot be predicted from conventional additive combination technology, and
The inventors have found that the heat discoloration resistance is remarkably excellent, and have reached the present invention. That is, the present invention relates to a method of manufacturing a resin composition comprising 100 parts by weight of a synthetic resin, a sulfur compound (A) represented by the following general formula (1), and one or more compounds (B) selected from phenol compounds. Metal soap (C) containing one or more metals selected from the group IIa, IIb, IIIb and IVb in the table was obtained by converting (A) :( B) :( C) = 1: 1 to 50:
It is a stabilized synthetic resin composition characterized by being blended in an amount of 10 to 500 (weight ratio) in an amount of 0.01 to 5 parts. R1-SH (1) (wherein, R1 represents an alkyl group having 6 to 25 carbon atoms, a phenyl group, an allyl group or an ester.) In the general formula (1) used in the present invention, In the sulfur compound shown, the substituent R1 in the formula is preferably an alkyl group, a phenyl group, an allyl group or an ester, particularly preferably an alkyl group having 10 to 12 carbon atoms, a phenyl group, an allyl group or an ester. What is shown by Formula (2) is also more preferable. [0009] (In the formula, R2 is hydrogen or an alkyl group having 1 to 20 carbon atoms, and n is an integer of 1 to 4.) Specific examples include 2-mercaptobenzimidazole and 2-mercaptobenzothiazole. . The phenolic compounds represented by the following general formulas (3) and (4) used in the present invention are:
It is a phenolic antioxidant and the substituent R4 has 8 carbon atoms.
Up to 40 phenyl or allyl groups are preferred. R4-OH (3) HO-R4-R4-OH (4) (in the formula, R4 represents a phenyl group or an allyl group having 8 to 40 carbon atoms). Is 2,6-di-t-butyl-p-cresol, stearyl-β- (3,5-di-t
-Butyl-4-hydroxyphenol) propionate, tetrakis [methylene-3 (3 ', 5'-di-t-
Butyl-4'-hydroxyphenyl) propionate]
Methane, n-octadecyl-3- (3 ', 5'-di-t
-Butyl-4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t
-Butylphenol), 2-t-butyl-6- (3′-
t-butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3-methyl-6-t-butylphenol) and the like. The metal soap (C) used in the present invention contains at least one metal selected from the group IIa, IIb, IIIb and IVb of the periodic table, especially cadmium, barium, calcium, Strontium, zinc, lead, tin, aluminum and magnesium are preferred, and stearate, laurate, ricinoleate, naphthenate and 2-ethylhexoate of the above metals are preferred. As specific examples, cadmium stearate, cadmium laurate, cadmium ricinoleate,
Cadmium naphthenate, cadmium 2ethylhexoate, barium stearate, barium laurate, barium ricinoleate, barium naphthenate, barium 2ethylhexoate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, zinc stearate, lauric acid zinc,
Examples include zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, tin stearate, aluminum stearate, and magnesium stearate. In the present invention, the compounds (A), (B) and (C) can be added to the synthetic resin in a conventional manner, for example, by adding the additive to the synthetic resin by melting simultaneously with other additives. A method is used in which an additive is blended with a pelletized mixture of the above and mixed with an extruder. Moreover, you may use together with the additive of a ultraviolet absorber and a lubricant. The synthetic resin stabilized by the present invention is a thermoplastic resin, and includes styrene resin, acrylic resin, polyamide resin and olefin resin, and styrene resin is particularly preferable. Styrene resins include polystyrene (including high impact polystyrene to which synthetic rubber has been added), styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene copolymer, and are particularly effective for polystyrene. In the present invention, there is a remarkable difference in heat discoloration resistance depending on the addition method. Particularly in the case of addition in a molten state, heat discoloration resistance is remarkably improved by adding and mixing the sulfur-based compound and the compound containing a metal so that they do not come into contact with each other in the molten state. Further, the effect of improvement is greater when the sulfur compound is added before the compound containing a metal.
The effect of this improvement is great at the molding temperature of 180 to 210 ° C. in addition to the improvement of the color under each molding condition. Next, the present invention will be described in more detail by way of examples. Example 1 A test resin shown in Table 1 was kneaded with an extruder at a temperature of 180 ° C. under the conditions of 180 ° C., and a test was conducted on moldability, heat and oxidation stability, and heat discoloration resistance. . Table 1 shows the results. [Table 1] For moldability, the releasability is evaluated in three stages based on the percentage of mold release of the molded product from the mold. For heat and oxidation stability, the molecular weight of the molded product is measured by GPC and evaluated by weight average molecular weight. The discoloration was evaluated by a reflection method using a color difference meter (Nippon Denshoku Kogyo Co., Ltd. 80) using a molding machine (thickness: 10 mm). Example 2 A test resin shown in Table 2 was kneaded with an extruder at 210.degree. C. under the temperature condition of 210.degree. C. to obtain a test resin. Was done. Table 2 shows the results. [Table 2] For moldability, the releasability was evaluated in three stages based on the mold release rate of the molded product from the mold. For heat and oxidation stability, the molecular weight of the molded product was measured by GPC and evaluated by weight average molecular weight. The discoloration was evaluated by a reflection method using a color difference meter (Nippon Denshoku Kogyo Co., Ltd. 80) using a molding machine (thickness: 10 mm). Example 3 Polystyrene was mixed with the test compounds shown in Table 3 at 240 ° C. in an extruder to obtain a test resin. Was done. Table 3 shows the results. [Table 3] The moldability was evaluated in terms of the releasability of the molded product from the mold in three stages. The heat and oxidation stability were evaluated by measuring the molecular weight of the molded product by GPC and evaluated by the weight average molecular weight. The discoloration was evaluated by a reflection method using a color difference meter (Nippon Denshoku Kogyo Co., Ltd. 80) using a molding machine (thickness: 10 mm). Example 4 A compound obtained by kneading a test compound shown in Table 4 in polystyrene with an extruder at a temperature of 180 ° C. was tested. As a resin, tests were conducted on moldability, heat and oxidation stability, and heat discoloration resistance. Table 4 shows the results. [Table 4] The moldability was evaluated in terms of the releasability of the molded article from the mold in three steps. The heat and oxidation stability were evaluated by measuring the molecular weight of the molded article by GPC and evaluated by the weight average molecular weight. The discoloration was evaluated by a reflection method using a color difference meter (Nippon Denshoku Kogyo Co., Ltd. 80) using a molding machine (thickness: 10 mm). When the combination of the additives of the present invention is blended with a synthetic resin, it simultaneously satisfies excellent moldability, excellent stability against heat and oxidation, and strong heat discoloration resistance. It is suitable for stabilization.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08

Claims (1)

(57) [Claims 1] 100 parts by weight of a synthetic resin and at least one compound selected from a sulfur compound (A) represented by the following general formula (1) and a phenol compound ( B) and a metal soap (C) containing one or more metals selected from the group IIa, IIb, IIIb and IVb of the periodic table;
(B): (C) = 1: 1 to 50:10 to 500 (weight ratio) in a ratio of 0.01 to 5 parts by weight. Embedded image wherein R 1 is an alkyl group having 6 to 25 carbon atoms, a phenyl group, an allyl group, an alkoxycarbonylalkyl group or
It represents an alkylcarbonyloxyalkyl group . )