JPH0725964B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a thermoplastic resin having a high thermal decomposition temperature and a high anti-coloring property as well as good heat resistance and impact resistance.

<Prior art> Styrene-based resins have high impact resistance, easy moldability, and easy secondary processing such as painting and plating.
Widely used for general purpose and semi-engineering applications.

As a method for improving the heat resistance of a styrene resin, a method using a-methylstyrene as a copolymerization component (Japanese Patent Publication No. 35-18194, Japanese Patent Publication No. 36-9592, and Japanese Patent Publication No. 42-89) is used.
28, JP-B-44-13149, JP-B-44-14936, JP-B-46-38694), and a method for introducing an imide bond (JP-B-56-39651, JP-A-57-39). 31914 publication,
JP-A-57-55901, JP-A-58-129043, JP-A-58-162616, JP-A-59-11322), etc., respectively, practical heat resistance, 100 ℃ or more, 110 Achieved above ℃.

In addition, polystyrene, styrene / acrylonitrile copolymer (SAN resin), acrylonitrile / butadiene / styrene copolymer (ABS resin) and styrene resin such as methyl methacrylate / butadiene / styrene copolymer (MBS resin) It is effective to add so-called heat stabilizers such as phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants to these for the purpose of preventing coloration and deterioration of impact resistance due to rubber deterioration. It is generally known that

Further, it is also known that the thermal decomposition temperature improving effect can be obtained by blending a specific hindered phenol with a resin containing α-methylstyrene (Japanese Patent Publication No. 58-56578).

<Problems to be Solved by the Invention> A resin containing an imide group introduced for the purpose of improving the heat resistance of a styrene-based resin has high heat resistance and high mechanical properties. Therefore, there was a problem that a color change occurred during melt-kneading and molding.

Therefore, the present inventors have improved the thermal decomposition temperature of a styrene-based thermoplastic resin composition containing N-phenylmaleimide,
As a result of diligent studies aimed at imparting excellent coloration-preventing properties to this, a specific hindered phenol-based compound and pentaerythritol-di-phosphite-based compound were blended in specific amounts to achieve specific heat stabilization. The inventors have found that the effects can be obtained and have reached the present invention.

<Means for Solving Problems> That is, the present invention provides (A) styrene and / or α-methylstyrene 20 to 80
%, Acrylonitrile 5 to 40% by weight, N-substituted phenylmaleimide 1 to 45% by weight, and a monomer mixture consisting of 0 to 40% by weight of another vinyl monomer copolymerizable therewith. Copolymer 5 to 90 parts by weight (B) Vinyl monomer mixture containing aromatic vinyl monomer and vinyl cyanide monomer as essential components in the presence of rubber polymer 2.0 to 80 parts by weight 5 to 70 parts by weight of a graft copolymer obtained by graft polymerization of (C) Obtained by polymerizing a vinyl-based monomer mixture containing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer as essential components. 0.05 to 4.0 parts by weight of a hindered phenol compound having a molecular weight of 500 or more and 0.05 parts by weight of pentaerythritol-di-phosphite compound to 100 parts by weight of a resin mixture consisting of 0 to 80 parts by weight of the copolymer.
It is intended to provide a thermoplastic resin composition characterized by being mixed in an amount of up to 4.0 parts by weight.

The copolymer (A) containing N-substituted maleimide (hereinafter abbreviated as copolymer (A)) used in the present invention is 20 to 80% by weight of styrene and / or α-methylstyrene and 5 to 40% by weight of acrylonitrile. , N-substituted phenylmaleimide 1
It is a copolymer obtained by polymerizing a monomer mixture consisting of ˜45% by weight and 0 to 40% by weight of another vinylic monomer copolymerizable therewith, and is excellent only in this copolymerization composition range. It is possible to form a resin composition which has both heat resistance and mechanical properties and has both heat resistance and impact resistance when blended with a graft copolymer.

Outside the above-mentioned copolymer composition range, the copolymer (A) is inferior in either or both of heat resistance and mechanical properties and cannot be put to practical use.

Other copolymerizable vinyl-based monomers used in the copolymer (A) of the present invention include vinyltoluene, p-tert-butylstyrene, aromatic vinyl-based monomers such as halogen-substituted styrene, and acrylic acid. And (meth) acrylic acid type monomers such as methacrylic acid and its methyl, ethyl, propyl and n-butyl esters, vinyl cyanide type monomers such as methacrylonitrile, and the following general formula (1) It is a maleimide-based monomer.

(However, in the formula, R ₁ , R ₂ , and R ₃ each independently represent hydrogen, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an aryl group, or the like). Include maleimide, N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide and N- (p-bromophenyl) maleimide.

For the production of the copolymer (A), known polymerization methods such as emulsion polymerization, solution polymerization and bulk polymerization can be used.

The graft copolymer (B) in the present invention is an essential component of an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of 20 to 80 parts by weight of a rubbery polymer, particularly 40 to 70 parts by weight. Further, it is obtained by graft-polymerizing 20 to 80 parts by weight, particularly 60 to 30 parts by weight of a vinyl-based monomer mixture consisting of other vinyl-based monomers copolymerizable with them, if necessary. . If the proportion of the rubbery polymer is less than 20 parts by weight, it is not possible to obtain a resin composition having both high heat distortion temperature and high impact strength. If it exceeds 80 parts by weight, the rubbery polymer becomes insufficiently dispersed and the resin It is not preferable because the appearance of the molded article made of the composition is impaired.

The rubbery polymer used for obtaining the graft copolymer (B) is polybutadiene rubber (PBD) styrene / butadiene copolymer rubber (SBR) and acrylonitrile /
Diene rubber such as butadiene copolymer rubber (NBR),
Examples thereof include acrylic rubber such as polybutyl acrylate and ethylene-propylene-non-conjugated diene rubber (EPDM).

Vinyl-based monomers used to obtain the graft copolymer (B) include styrene, p-methylstyrene and p-tert-
Nuclear substituted alkyl styrenes such as butyl styrene and α
-Aromatic vinyl-based monomers such as methylstyrene and vinyl cyanide-based monomers such as acrylonitrile and methacrylonitrile are essential components, and other vinyl-based monomers copolymerizable with these are acrylic. Acid, methacrylic acid and its (meth) acrylic acid monomers such as methyl, ethyl, propyl and n-butyl ester, maleimide, N-methylmaleimide, N-ethylmaleimide, N
-Butyl maleimide, N-cyclohexyl maleimide,
N-phenylmaleimide, N- (p-bromophenyl)
Examples thereof include maleimide-based monomers such as maleimide.

There is no particular limitation on the method for producing the graft copolymer (B), and known polymerization methods such as emulsion polymerization, emulsion-suspension polymerization, suspension polymerization, solution polymerization, bulk polymerization, and bulk-suspension polymerization are used. be able to.

The copolymer (C) used in the present invention is a styrene, a nuclear-substituted alkylstyrene such as p-methylstyrene or p-tert-butylstyrene, an aromatic vinyl monomer such as α-methylstyrene, and acrylonitrile or methacrylonitrile. A vinyl cyanide monomer such as nitrile is used as an essential component, and if necessary, acrylic acid, methacrylic acid, and their (meth) acrylic acid monomers such as methyl, ethyl, propyl, and n-butyl esters are included. A copolymer obtained by polymerizing a vinyl-based monomer mixture, for example, acrylonitrile-styrene copolymer, acrylonitrile-styrene-methyl methacrylate copolymer, acrylonitrile-
p-methylstyrene copolymer, acrylonitrile-p-
Examples thereof include a methylstyrene-methylmethacrylate copolymer, an acrylonitrile-α-methylstyrene copolymer and an acrylonitrile-α-methylstyrene-methylmethacrylate copolymer.

Regarding the method for producing the copolymer (C), known polymerization methods such as emulsion polymerization, suspension polymerization, bulk polymerization and bulk-suspension polymerization can be used.

The resin mixture before the addition of the stabilizer is the copolymer (A) 5 to 90
Parts by weight, particularly 20 to 85 parts by weight, 5 to 70 parts by weight of the above graft copolymer (B), especially 10 to 50 parts by weight and 0 to 80 parts by weight of the above copolymer (C) (A) + (B ) + (C) so that the total amount thereof is 100 parts by weight. If the proportion of the copolymer (A) is less than 5 parts by weight, the heat distortion temperature of the resin composition is insufficient, and if it exceeds 90 parts by weight, the impact resistance of the resin composition decreases, which is not preferable. When the proportion of the graft copolymer (B) is 5 parts by weight or less, the impact resistance of the resin composition is insufficient, and when it exceeds 70 parts by weight, a high heat distortion temperature cannot be obtained, which is not preferable. Further, if the proportion of the copolymer (C) exceeds 80 parts by weight, both the heat distortion temperature and the impact resistance become low, which is not desirable.

The proportion of the rubbery polymer (contained in the graft copolymer (B)) in the entire composition is preferably 1 to 40% by weight, particularly 5 to 30% by weight. If it is less than 40% by weight, the impact resistance of the resin composition will be low, and if it exceeds 40% by weight, the processability and tensile strength of the resin composition will be significantly reduced, which is not desirable.

Examples of the hindered phenol compound having a molecular weight of 500 or more used in the present invention include the following.

(1) 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene (2) 1,3,5-tris (3 ', 5'-di-tert-butyl-4
-Hydroxybenzyl) isocyanurate (3) n-octadecyl-3- (4'-hydroxy-
3 ', 5'-di-tert-butylphenol) propionate (4) 1,1,3-tris (2-methyl-4-hydroxy-)
5-tert-Butylphenyl) butane (5) Tetrakis- [methylene-3- (3 ', 5'-tert-butyl-4'-hydroxyphenyl) propionate]
Methane (6) Hexamethylene glycol bis [β- (3,5-di-tert-butyl-4-hydroxy-phenol) propionate (7) Tris [β- (3,5-di-tert-butyl-4-hydroxy) (Phenyl) propionyl-oxyethyl] isocyanurate (8) Bis [3,3'-bis (4'-hydroxy-3'-
(Tert-Butylphenyl) butyric acid] glycol ester (9) 6- (4-hydroxy-3,5-di-tert-butylanilino) -2,4-bis-octyl-thio-1,3,5-triazine ( 10) Terephthaloxydi (2,6-di-methyl-4-tert-butyl-3-hydroxybenzyl sulfide) (11) N, N'-hexamethylene-bis (3,5-di-tert-butyl-4-hydroxy) -Hydrocinnamide) (12) 2,2-thio [diethyl-bis-3 (3,5-di-tert-butyl-4-hydroxyphenol) propionate Any of these hindered phenolic compounds can improve thermal stability. Effective, but especially (1), (2)
The effect of using the compounds of (3) and (3) is particularly remarkable.

The blending amount of these hindered phenol compounds having a molecular weight of 500 or more is 0.05 with respect to 100 parts by weight of a resin mixture obtained by blending the copolymer (A), the graft copolymer (B) and the copolymer (C). 〜4.0 parts by weight, preferably 0.1-2.0 parts by weight. If the blending amount is less than 0.05 parts by weight, the effect of improving thermal stability is not sufficiently exhibited, and if it exceeds 4.0 parts by weight, there is no further effect and conversely the mechanical properties deteriorate, which is not preferable.

In addition, even if a hindered phenol compound having a molecular weight of less than 500 is added, no remarkable effect appears in improving the thermal stability.

Examples of the pentaerythritol-di-phosphite compound used in the present invention include the following.

(1) Di-stearyl pentaerythritol-di-phosphite (2) Bis (2,4-di-tert-butylphenyl) pentaerythritol-di-phosphite (3) Bis-nonylphenyl pentaerythritol-di-phosphite (4) Nonylphenyl α- (4-oxyphenyl) -P
-Cumylphenyl pentaerythritol-di-phosphite (5) bis [2-tert-butyl, 5-methyl-S- (3-tert-butyl, 6-methyl, 4-oxyphenyl) -P-thiophenyl] penta Erythritol diphosphite All of these pentaerythritol-di-phosphite compounds are effective in improving the thermal stability, but above all, the effects when using the compounds of (1), (2) and (3). Is especially noticeable.

The blending amounts of these pentaerythritol-di-phosphite compounds are copolymer (A) and graft copolymer (B).
0.05 to 4.0 parts by weight, preferably 0.07 to 2.0 parts by weight, is suitable for 100 parts by weight of the resin mixture prepared by blending with the copolymer (C). If the blending amount is less than 0.05 parts by weight, the effect of improving thermal stability is not sufficiently exhibited, and if it exceeds 4.0 parts by weight, there is no further effect and conversely the mechanical properties deteriorate, which is not preferable.

By using the hindered phenol-based compound and the pentaerythritol-di-phosphite-based compound in combination at a predetermined ratio, the effect of improving the thermal decomposition temperature and preventing coloration can be obtained. It is necessary to use these in combination, and the combined use produces a thermal stabilization effect that is more than the addition effect of both.
It can be obtained by adding a small amount of stabilizer.

The hindered phenol-based compound alone improves the thermal decomposition temperature but is inferior in coloration-preventing property. The pentaerythritol-di-phosphite-based compound alone improves the coloration-inhibiting property but is not preferable because the thermal decomposition temperature is insufficient.

In addition to the above-mentioned stabilizers, sulfur-based or phosphorus-based antioxidants can also be used as secondary antioxidants, as is often done.

In the present invention, the method of mixing the copolymer (A), the graft copolymer (B) and the copolymer (C) is not particularly limited, but usually an extruder, a Banbury mixer, a kneader, a roll or the like is used. Melt kneaded.

The thermoplastic resin composition of the present invention further comprises another thermoplastic polymer such as styrene-maleic anhydride copolymer, p-tert.
-Butylstyrene-maleic anhydride copolymer, p-methylstyrene-maleic anhydride copolymer, polycarbonate, polyamide, polybutylene terephthalate, polyethylene terephthalate and polyphenylene oxide can be mixed to adjust the desired performance. . Also, during or after kneading, heat stabilizer, ultraviolet absorber,
Light stabilizer, flame retardant, lubricant, colorant, pigment, various additives,
It is also possible to mix glass fibers, metal fibers, reinforcing agents, fillers and the like.

<Examples> Details of the present invention will be described below with reference to Examples.

The heat distortion temperature in the examples was measured according to ASTM D-648-56, and the Izod impact value was measured according to ASTM D-256-56 Method A. Pyrolysis temperature is 10 ℃ / in a nitrogen stream using a thermobalance
The temperature was raised at a rate of minutes to measure the weight change of the sample, and the temperature at which the sample weight decreased by 3% by weight was defined as the thermal decomposition temperature.

The colorability is measured by using a color machine to measure the yellowness of the sample.
The index (Yellowness Index / YI value) was measured and used as an index.

Example 1 Copolymers (A) (A-1), Copolymers (C) (C-1) and Graft Copolymers (B) below having the compositions shown in Table 1
(B-1), and 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl)
Benzene and di-stearyl pentaerythritol-di-
Phosphite was blended in a ratio shown in Table 2 and melt-kneaded.

B-1: Styrene 22.5 in the presence of 70 parts of polybutadiene rubber
Part and acrylonitrile 7.5 parts graft copolymer obtained by polymerizing the resulting resin composition heat distortion temperature, Izod impact value,
The thermal decomposition temperature and YI value were measured.

The results are summarized in Table 2.

This composition was excellent in heat distortion temperature, Izod impact value and thermal decomposition temperature, and low in YI value.

Example 2 Copolymer (A) (A-1, A-2, A) having the composition shown in Table 1
-3) and the copolymer (C) (C-1, C-2) and the graft copolymer (B) (B-1: the above, B-2: the following) and the stabilizer shown in Table 2 It was blended in the blending ratio of 2 and melt-kneaded.

B-2: 18 parts of styrene in the presence of 60 parts of polybutadiene rubber,
Graft copolymer obtained by polymerizing 18 parts of methyl methacrylate and 4 parts of acrylonitrile. Heat distortion temperature, Izod impact value of resin composition obtained,
The thermal decomposition temperature and YI value were measured. The results are summarized in Table 2. Heat distortion temperature of these compositions, Izod impact value,
Both pyrolysis temperatures were high and YI values were low.

Comparative Example Copolymer (A-4, A-5, A-6) having the composition shown in Table 1
And the graft copolymer (B) (B-1, B) used in the examples.
-2), the copolymer (C) (C-1, C-2) and the stabilizer shown in Table 3 were compounded in the composition shown in Table 3 and melt-kneaded.

The thermal deformation temperature, Izod impact value, thermal decomposition temperature and YI value were measured in the same manner as in Example 1. The results are summarized in Table 3.

In the copolymer (A), when the amount of the N-substituted maleimide copolymerized is less than 1% by weight, the heat resistance is insufficient (Experiment No. 15).
If it exceeds 5% by weight, the impact resistance deteriorates (Experiment No. 16).

Further, when the amount of acrylonitrile exceeded 40% by weight, the anti-coloring property was significantly reduced (Experiment No. 17).

When the blending amount of the graft copolymer (B) was less than 5 parts, the impact resistance was insufficient (Experiment No. 18), and when it exceeded 70 parts by weight, the heat distortion temperature was lowered (Experiment No. 19). When the compounding amount of the copolymer (C) exceeded 80 parts by weight, the heat distortion temperature decreased (Experiment No. 20).

When only hindered phenol compounds were used as stabilizers, the coloration-preventing property was insufficient (Experiment No. 21, 22), and when only pentaerythritol-di-phosphite compounds were used, the thermal decomposition temperature increased. The degree was low (Experiment No.23,
twenty four).

The use of hindered phenolic compounds with a molecular weight of less than 500 did not have a sufficient effect on improving the thermal decomposition temperature (Experiment N
25.26). When the compounding amount of each stabilizer was less than 0.05 part, the effect of addition was small (Experiment No. 27), and when more than 4.0 parts, the heat distortion temperature etc. decreased (Experiment No. 28).

From the results of Tables 2 and 3, only when the hindered phenol compound having a molecular weight of 500 or more and the pentaerythritol-di-phosphite compound are used in combination, the thermal decomposition temperature is high, the coloring resistance is high, and the heat resistance is excellent. It is clear that different thermoplastic compositions are obtained.

<Effects of the Invention> As described above, the resin composition of the present invention is high in thermal decomposition temperature and coloration-preventing property, and is excellent in both heat resistance and impact resistance.

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Claims (1)

[Claims] 1. A) 20 to 80% by weight of styrene and / or .alpha.-methylstyrene, 5 to 40% by weight of acrylonitrile, 1 to 45% by weight of N-substituted phenylmaleimide and other vinylic copolymerizable with them. Aromatic vinyl monomer in the presence of 5 to 90 parts by weight of a copolymer obtained by polymerizing a monomer mixture consisting of 0 to 40% by weight of a monomer (B) 20 to 80 parts by weight of a rubbery polymer. And a graft copolymer obtained by graft-polymerizing a vinyl-based monomer mixture containing a vinyl cyanide-based monomer as an essential component 5 to 70 parts by weight (C) Aromatic vinyl-based monomer and vinyl cyanide-based Copolymer obtained by polymerizing a vinyl-based monomer mixture containing a monomer as an essential component A hindered phenolic compound with a molecular weight of 500 or more 0.05 to 4.0 per 100 parts by weight of a resin mixture consisting of 0 to 80 parts by weight Parts by weight and pentaerythritol - di - phosphite compound 0.05
A thermoplastic resin composition characterized by containing up to 4.0 parts by weight.