JPH03215552A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To provide the title composition excellent in heat stability, etc., by adding three specified antioxidants to a mixture comprising a polyphenylene ether resin, a styrene resin and a rubbery elastomer in a specified weight ratio. CONSTITUTION:15-80 pts.wt. polyphenylene ether resin, 85-20 pts.wt. styrene resin (e.g. polystyrene) and 0-25 pts.wt. rubbery elastomer (e.g. polybutadiene) are mixed together. 0.05-3 pts.wt. thioether antioxidant of the formula (wherein R is 6-20C alkyl), e.g. tetrakis[methylene-3-(laurylthio)propionate]methane, 0.05-3 pts.wt. phenolic antioxidant and 0.05-3 pts.wt. phosphite antioxidant (e.g. distearylpentaerythritol diphosphite) are added to 100 pts.wt. obtained resin mixture to produce a thermoplastic resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyphenylene ether thermoplastic resin composition having excellent thermal stability.

(Prior art) A polyphenylene ether resin composition made by mixing a polyphenylene ether resin and a styrene resin is used as a resin composition for injection molding, blow molding, vacuum forming, etc. as a resin composition with excellent heat resistance and impact resistance. used as a thing.

Since this resin composition has relatively low fluidity, it is necessary to set a high melting temperature in the molding machine or in the extrusion mill used to create sheets for vacuum forming, which results in the decomposition of each component in the resin composition. Therefore, there are problems such as discoloration of the molded product, generation of silver streaks on the surface of the molded product, and deterioration of mechanical properties.Especially in blow molding and sheet extrusion, resin stagnation inside the molding machine and extruder can occur. There was a problem in that the resin deteriorated significantly due to the long time.

As a countermeasure to this situation, attempts have been made to improve the thermal stability of resin compositions by adding hindered phenol antioxidants and phosphite antioxidants.

(Problem to be solved by the invention) However, most of these antioxidants are polyethylene,
It is used to improve the thermal stability of polypropylene, ABS, vinyl chloride resin, etc., and compared to such resins, polyphenylene ether resin compositions have a temperature of 50 to 50 ℃ during extrusion shaping and molding. Since the temperature is as high as 100°C, there is a problem that these antioxidants have insufficient ability to improve the thermal stability during molding of polyphenylene ether resin compositions. Currently, there is a demand for the development of resin compositions.

(Means for Solving the Problems) In view of the above circumstances, the present inventors have conducted extensive studies on the development of polyphenylene ether resin compositions with excellent thermal stability. The inventors have discovered that thermal stability can be improved by adding a combination of oxidizing agents, and have arrived at the present invention.

That is, the gist of the present invention is 100 parts by weight of a resin mixture consisting of (A) 15 to 80 parts by weight of a polyphenylene ether resin, (B) 20 to 85 parts by weight of a styrene resin, and (C) 0 to 25 parts by weight of a rubbery elastic material. (D) 0.05 of the thioether antioxidant represented by the following structural formula (1)
~3 parts by weight, O 11 C (CH.OCCH.CH.SR). (1)(
E) A thermoplastic resin composition containing 0.05 to 3 parts by weight of a phenolic antioxidant and (F) 0.05 to 3 parts by weight of a phosphite antioxidant.

The polyphenylene ether resin used in the present invention is a phenylene ether homopolymer which may have one or more substituents or a copolymer of phenylene ethers having different substituents, and the substituents include methyl, ethyl, Examples include lower alkyl groups such as proyl.

Specific examples of such polyphenylene ether resins include poly(2,6-dimethyl-1,4-phenylene) ether and poly(2,6-diethyl-1,4-phenylene).
ether, poly(2,6-dibrobyl-1,4-phenylene)ether, poly(2-methyl-6-ethyl-1.
4-phenylene) ether, poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether,
(2,6-dimethyl-1,4-phenylene)ether and (2,3.6-trimethyl-1,4-phenylene)
Copolymer with ether, (2,6-diethyl-1,4-
phenylene)ether and (2,3.6-trimethyl-
Copolymer with 1,4-phenylene)ether, (2.6
-dimethyl-1,4-phenylene)ether and (2,3
．． Examples include copolymers with 6-triethyl-1,4-phenylene) ether, among which poly(2,6-dimethyl-1,4-phenylene) ether and (2,6-dimethyl- 1,4-phenylene) ether and (2,3,6-trimethyl-1,4-phenylene)
Copolymers with ethers are preferred, and poly(2,6-dimethyl-1,4-phenylene) ether is most preferred.

The degree of polymerization of the polyphenylene ether resin used in the present invention is not particularly limited;
/g is preferably used. Reduced viscosity is 0.3d
When the reduced viscosity is less than 0.7 dβ/g, the thermal stability of the resin composition tends to decrease, and when the reduced viscosity exceeds 0.7 dβ/g, the moldability of the composition tends to be impaired. The polyphenylene ether resin may be used alone2
It may also be a mixture of more than one type of polyphenylene ether.

The styrenic resin used in the present invention is a polymer containing at least 50% by weight of styrene or its derivatives, and examples of styrene derivatives include α-methylstyrene and chlorostyrene. Specific examples of styrene resins include homopolymers such as polystyrene, polyα-methylstyrene, and polychlorostyrene, styrene-acrylic nitrile copolymers, styrene-methyl methacrylate copolymers, styrene and α-methylstyrene, and chlorostyrene. copolymers of styrene monomers such as copolymers with styrene, copolymers of styrene with other vinyl monomers such as styrene-acrylonitrile-methyl methacrylate copolymers, and modified with rubbers such as impact-resistant polystyrene. An example of this is polystyrene. Among these styrenic resins, polystyrene and impact-resistant polystyrene are preferably used. This styrenic resin may be produced by any polymerization method including bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, and bulk suspension polymerization.

In the present invention, a rubber-like elastic body may be included in the resin mixture. This rubber-like elastic material is a polymer that exhibits rubber properties at room temperature, and includes polybutadiene, butadiene-styrene copolymer, butadiene-acrylic nitrile copolymer, styrene-butadiene-styrene block copolymer, and polyisoprene. , isobrene-styrene copolymers, den-based rubbers such as polychlorobutadiene, isobutylene-based rubbers, (meth)acrylic acid ester-based rubbers such as butyl acrylate crosslinked polymers, and olefin-based rubbers such as ethylene-brobylene copolymers. , urethane rubber, polyether rubber such as polypropylene oxide, silicone rubber, and shrimp chlorohydrin rubber. Furthermore, a graft-modified rubber-like elastic body obtained by graft-modifying the above-mentioned rubber with various polymers may also be used. Components used in this grafting include aromatic alganyl monomers such as styrene, α-methylstyrene, and vinyltoluene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, methyl methacrylate, ethyl acrylate, and butyl acrylate. Vinyl monomers such as (meth)acrylic acid ester monomers can be mentioned, and these two
You may use combinations of more than one species.

Among graft-modified rubber-like elastomers, graft-modified composite rubber, which is made by graft-polymerizing the above-mentioned vinyl monomers onto a composite rubber in which polyorganosiloxane rubber and polyalkyl (meth)acrylate rubber are intertwined with each other, has good impact resistance. preferred from the viewpoint of stability and thermal stability.

This graft-modified composite rubber can be produced by the method described in JP-A-63-69859.

When a rubber-like elastic body is used in the present invention, this elastic body is dispersed in a ball field in a resin composition, and its average particle size is 1 μm.
The number average particle size of the elastic phase of the composite rubber is preferably 0.08 to 0.6 μm when the elastic body is a graft-modified composite rubber.

The weight composition ratio of components (A), (B), and (C) in the present invention is based on a total of 100 parts by weight of the three components (A), (B), and (C) (collectively referred to as a resin mixture). Component (A) should be 15 to 80 parts by weight, Component (B) should be 20 to 85 parts by weight, and Component (C) should be 0 to 25 parts by weight.

If the amount of component (A) is less than 15 parts by weight, the heat resistance will be low, and if the amount exceeds 80 parts by weight, the fluidity will be poor and molding will be difficult. When component (B) is less than 20 parts by weight, molding becomes difficult, and when it exceeds 85 parts by weight, heat resistance becomes low. Component (C) may or may not be used, but its use is more advantageous in terms of developing impact resistance. However, if component (C) exceeds 25 parts by weight, it becomes unfavorable in terms of mechanical properties, heat resistance, etc.

In the present invention, 0.0% of the ether antioxidant represented by structural formula (1) is used per 100 parts by weight of the resin mixture.
5 parts by weight, 0.05 parts by weight of a phenolic antioxidant, and 0.05 parts by weight of a phosphite antioxidant. It is only when these three types of antioxidants are used in combination that the above resin mixture can be given thermal stability that can withstand the temperature during molding. A combination of these cannot provide sufficient thermal stability.

The amount of these antioxidants to be used must be the above-mentioned amount; if it is less than the lower limit, the effect of the addition of the antioxidant will not be expressed, and if it is used more than the upper limit, the heat resistance of the composition will decrease, so it is preferable. "do not have.

In the present invention, it is necessary to use a thioether antioxidant represented by the structural formula (1), and instead, didodecyl-3,3°, which is used as an antioxidant for various elastomers, polyolefins, and ABS. - Even if thiodib bionate is used, thermal stability cannot be improved under the temperature conditions used for shaping the resin mixture used in the present invention, and furthermore, the surface appearance of the molded product deteriorates due to decomposition of the antioxidant. A problem arises.

Specific examples of the antioxidant represented by structural formula (1) include tetrakis[methylene-3-(hexylthio)probionate]methane, tetrakis[methylene-3-(decylthio)probionate]methanetetrakis[methylene-3-
(laurylthio)probionate [methane and tetrakis[methylene-3-(octylthio)probionate]
Examples include methane, among which tetrakis[methylene-3-(laurylthio)probionate]methane is preferably used.

The phenolic antioxidant used in the present invention is a hindered phenol compound in which a bulky group exists at the ortho position to the hydroxyl group of the phenol compound.
, 1,3-tris(2-methyl-4-hydroxy-5-
tert-butylphenyl)butane, n-octadecyl-3-(3゜,5-di-tert-butyl-4-hydroxyphenyl)probionate, tetrakis[methylene-3-(3゜,5゜-di-tert-butyl-4゛) -hydroxyphenyl)probionate] methane, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)probionate], pentaerythritol tetrakis[3- (3.
5-tert-butyl-4-hydroxyphenyl)
Brobionate]. 2.6-jert-butyl-4
-methylphenol, 2.2-methylenebis(4-methyl-6-tert-butylphenol), 2.2-methylenebis(4-ethyl-6-tert-butylphenol), etc. Among these, n- Octadecyl
3-(3°,5-di-tert-butyl-4°-hydroxyphenyl) propynate is preferred.

The phosphite-based antioxidants used in the present invention include those based on phosphorous esters, those based on phosphophenanthrene compounds, and other phosphites, and specific examples include tris(nonylphenyl) phosphorus. phyto, distearylbentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl) phosphite, -butylphenyl)-4.4
- Diphenylene phosphonite, bis(2,6-di-t)
Examples include ert-butyl-4-methylphenyl) pentaerythritol diphosphite, and as phosphite antioxidants, those having a pentaerythritol skeleton in the molecule are preferred. -butylphenyl) pentaerythritol diphosphite and bis(2,6-c-tert-butyl-4-methylphenyl) pentaerythritol diphosphite can be mentioned as preferred.

In the present invention, by using these three types of antioxidants in combination, thermal discoloration and thermal deterioration under high temperature conditions are suppressed synergistically, and impact resistance is effectively maintained.

In addition to the above-mentioned components, the thermoplastic resin composition of the present invention may optionally include stearic acid ester, paraffin wax,
Lubricants such as stearyl alcohol, phthalate esters,
Plasticizers such as epoxy compounds, colorants such as carbon black and titanium oxide, fillers such as calcium carbonate and asbestos, reinforcing materials such as glass fibers and carbon fibers, light stabilizers, and the like may be added.

The thermoplastic resin composition of the present invention can be produced by mixing the above-mentioned components using a Henschel mixer or the like, and then kneading the mixture using a vented cross-wire extruder, a Banbury mixer, a roll, or the like, and forming the mixture into pellets.

(Example) The present invention will be described in more detail below using Examples and Comparative Examples.

In the following, thermal stability was measured at a cylinder temperature of 270°C using a vented twin-screw extruder (manufactured by Werner & Friederer ■, ZSK-30 type, screw diameter 30 mm).
Degree of discoloration and Silver's 1-Leak occurrence measured using a flat plate of 100 mm x 100 mm x 3 mm molded with an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., Promat 165/75 type) using a cross-wire extrusion pellet made with It was measured using the number of pieces as a scale.

The degree of discoloration is the difference in color (degree of discoloration △E) before and after a flat plate injection molded at a cylinder temperature of 280℃ is placed in a 120℃ gear oven and aged for 250 hours according to ASTM.
Measurement was performed using a Suga testing machine (Kiyuki Color Computer Model SM-4-2) in accordance with D-1925.

For silver streaks, flat plates are formed by varying the cylinder temperature setting, and the lowest temperature at which the number of silver streaks per plate averaged over 10 plates is 10 or more is called the silver streak generation temperature ("C"). And so.

In addition, unless otherwise specified below, "parts" indicate "parts by weight."

Graft-modified composite rubber (B
-1) and (B-2) were synthesized according to the following reference examples.

Reference Example 1 Graft Human Rubber B-1 2 parts of synthetic tetraethoxysilane, 0.5 parts of γ-methacrylicoxybutylmethoxymethylsilane, and 97.5 parts of octamethylcyctotetrasiloxane were mixed, and 100 parts of siloxane mixture I got the department.

100 parts of the above siloxane mixture was added to 200 parts of distilled water in which 1 part each of sodium dodecylbenzenesulfonate and dodecylbenzenesulfonic acid were dissolved, and after pre-stirring at 10,000 rpm with a homomixer, the mixture was mixed with 300 kg/cm2 using a homogenizer. The mixture was emulsified under a pressure of 100 to obtain an organosiloxane latex. This latex was transferred to a separable flask equipped with a condenser and a stirrer, and heated at 80°C for 5 hours while stirring and mixing.
The latex was allowed to stand for 48 hours at 0.degree. C., and then the pH of the latex was adjusted to 6.9 with an aqueous sodium hydroxide solution to complete the polymerization, thereby obtaining a polyorganosiloxane rubber latex.

The polymerization rate of polyorganosiloxane rubber is 89.7%, and the average particle size of polyorganosiloxane rubber is 0.16.
It was μm.

Collect 25 parts of this polyorganosiloxane rubber latex, put it in a glass flask equipped with a stirrer, and add 53 parts of distilled water.
After adding 3 parts of nitrogen and purging the system with nitrogen, the internal temperature was raised to 60°C, and 7.35 parts of n-butyl acrylate, 0.15 parts of allyl methacrylate, and 0.038 parts of tert-butyl hydroperoxide The mixed solution was added thereto and stirring was continued for 30 minutes to allow the mixed solution to penetrate into the polyorganosiloxane rubber particles. Next, add 0.0 ferrous sulfate to this.
0025 parts, ethylenediaminetetraacetic acid disodium salt 0
．． 00075 parts, Rongalit 0.06 parts and distilled water 4
．． Two parts of the mixed solution were charged, radical polymerization of the above monomers was started in that state, and then the internal temperature was maintained at 70° C. for 2 hours to complete the polymerization to obtain a composite rubber latex. A portion of this latex was sampled and the average particle size of the composite rubber was measured and found to be 0.20 ILm. Further, this latex was dried to obtain a solid substance, which was extracted with toluene at 90°C for 12 hours, and the gel content was measured and found to be 98.0% by weight. A mixed solution of 0.048 parts of tert-butyl hydride peroxide and 10 parts of styrene was added dropwise to this composite rubber latex at 70°C over 60 minutes, and then held at 70°C for 4 hours to complete graft polymerization to the composite rubber. did. The polymerization conversion rate of styrene was 98.5%. The obtained graft-modified composite rubber latex was dropped into 200 parts of hot water containing 1.5% by weight of calcium chloride, coagulated, separated, washed, and dried to obtain a graft-modified composite rubber (B-1).

Reference Example 2 Graft Human Rubber B-2 117 parts by weight of the polyorganosiloxane rubber latex obtained in Reference Example 1 was collected and placed in a glass flask equipped with a stirrer, and 57.5 parts of distilled water was added to the system. After replacing the inside with nitrogen, the internal temperature was raised to 60°C, and 49 parts of n-butyl acrylate, 1.0 part of allyl metadunolate, and tert-
A mixed solution containing 0.26 parts of butylhydrober 1 oxide was added thereto and stirred for 3C minutes to allow the mixed solution to penetrate into the polyorganosiloxane rubber particles. Next, a mixed solution of 0.002 parts of iron-iron sulfate, 0.006 parts of ethylenediaminetetraacetic acid nilatrium salt, 0.26 parts of Rongalite, and 5 parts of distilled water was charged, and radical polymerization was started with the above monomers in that state. After rinsing, the mixture was maintained at an internal temperature of 70° C. for 2 hours to complete polymerization to obtain a composite rubber latex. A portion of this latex was sampled and the average particle size of the composite rubber was measured and found to be 0.19 μm. Further, this latex was dried to obtain a solid substance, which was extracted with toluene at 90°C for 12P, and the gel content was measured and found to be 97.3 m%. A mixed solution of 0.12 parts of tert-butylic hydroxide and 15 parts of methyl methacrylate was added dropwise to this composite rubber latex at 70°C for 15 minutes, and then at 70°C.
The mixture was held for 4 hours to complete the graft polymerization to the composite rubber. The polymerization conversion rate of methyl methacrylate was 99.5%. The obtained graft-modified composite rubber latex was dropped into 200 parts of hot water containing 1.5% by weight of calcium chloride to coagulate, separate, wash, and dry to obtain a graft-modified composite rubber (B-2).

Examples 1 to 6, Comparative Examples 1 to 8 The compositions having the formulations listed in Table 1 were formed into cross-wire pellets, and a flat plate was injection molded to evaluate thermal stability.

The results are shown in Table 1.

In addition, in the table, S-1 represents tetrakis[methylene-3-(laurylthio)probionate]methane, and H-1 represents n-octadecyl-3-(3',5-di-tert-butyl-4-hydroxyphenyl). Probionate, H-2 is 2,2゜methylenebis(4-methyl-6-
tert-butylphenol), and P-1 is bis(
2,4-di-tert-butylphenyl) pentaerythritol diphosphite, P-2 is tetrakis (
2,4-di-tert-butylphenyl)-4,4-diphenylene phosphonite.

In addition, as polyphenylene ether, poly(2,6-
Dimethyl-1,4-phenylene) ether was used, and the boristyrene was S-Brite 7 manufactured by Nippon Boristyrene ■.
The impact-resistant polystyrene is Japan polystyrene■
S-Bright 5003B manufactured by Manufacturer Co., Ltd. was used.

As is clear from Table 1, it can be seen that the composition of the present invention has superior thermal stability compared to those without, or with one or two antioxidants.

(Effects of the Invention) As described above, the thermoplastic resin composition of the present invention has excellent thermal stability even under high temperature conditions during molding by adding a specific combination of antioxidants to the polyphenylene ether resin composition. It has the characteristic of indicating gender.

Claims (1)

[Claims] 1) 100 parts by weight of a resin mixture consisting of (A) 15 to 80 parts by weight of a polyphenylene ether resin, (B) 20 to 85 parts by weight of a styrene resin, and (C) 0 to 25 parts by weight of a rubbery elastic material. (D) 0.05 to 3 parts by weight of a thioether antioxidant represented by the structural formula (1) below, ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (1) (E) Phenolic antioxidant 0 A thermoplastic resin composition containing 0.05 to 3 parts by weight and (F) 0.05 to 3 parts by weight of a phosphite antioxidant.