JPH05132597A - Heat-resistant styrene resin composition - Google Patents

Abstract

PURPOSE:To improve the flatwise impact strength and stretchability without practically deteriorating the heat resistance and rigidity of a maleimide-modified styrene resin. CONSTITUTION:The objective composition compriser 0.5-3.5 pts.wt. ethylene copolymer (A) obtained by copolymerizing 40-90wt.% ethylene, 15-40wt.% acrylate having a 1-8C alkyl group, 6-20wt.% carbon monoxide, and 0-20wt.% other vinyl monomer and 100 pts.wt. maleimide-modified styrene resin (B) having a maleimide content of 3-30wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant styrene resin composition, and more particularly to a styrene resin composition containing maleimides having excellent surface impact strength and stretch ratio.

[0002]

PRIOR ART AND PROBLEM TO BE SOLVED BY THE INVENTION A containing acrylonitrile, butadiene and styrene as constituent components
The BS resin is a molding material having excellent rigidity, impact strength, elongation and fluidity, and is widely used for electrical, OA-related housings, interior / exterior of automobiles, and miscellaneous goods.
In addition, among these, a modified styrene resin in which a part or all of styrene or acrylonitrile is replaced with alphamethylstyrene or maleimides has been developed for applications requiring heat resistance. Recently, maleimide-modified styrene resins have attracted particular attention because styrene resins having higher heat resistance and lower thermal decomposability can be obtained by modifying with maleimides than modifying with alphamethylstyrene. However, when the styrene resin is modified with maleimides, in particular, the surface impact strength and the stretch ratio decrease.
It is difficult to put into practical use in some applications where performance is demanding.

In general, the impact applied when the actual molded product is put into practical use is often applied to the surface of the molded product. On the other hand, Izod impact strength (with a notch) is the most widely used to measure the impact strength of ABS resin and similar resins, but Izod impact strength cuts a molded article by a lateral impact. It represents the energy required for. Because of this, it cannot be said that the correspondence between the Izod impact strength and the practical impact strength is good. The maleimide-modified styrene resin has only a slight decrease in Izod impact strength due to maleimides, but the reduction in surface impact strength is significant, and as a result, practical impact resistance becomes a problem. Surface impact strength is extremely important. Further, as a mechanism when the ABS resin or a similar resin is broken, it is generally known that the resin at a position where a shock is applied is locally stretched and then broken. For this reason, in normal applications, the higher the draw ratio, the higher the reliability of the occurrence of fracture.

Thus, it is desired that the maleimide-modified styrene resin has improved surface impact strength and stretch ratio while maintaining good heat resistance. There is a method of increasing the content rate of butadiene rubber in order to improve the surface impact strength and the draw ratio, but heat resistance, rigidity, and fluidity are reduced, which is a practically large limitation. In addition, improvements with various additives have been tried, but it is hard to say that they have been successful in practice.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a maleimide-modified styrene resin and a specific composition ratio of an ethylene-acrylate having an alkyl group having 1 to 8 carbon atoms. By mixing with a specific amount of carbon oxide-based copolymer, the heat resistance of the maleimide-modified styrene resin, practically, without impairing the surface impact strength, succeeded in improving the stretch ratio, further, The present invention has been accomplished by finding that the improvement effect can be enhanced by adding a specific amount of polysiloxane or ethylenebisstearylamide. That is, the present invention includes (A) 40 to 90% by weight of ethylene, 15 to 40% by weight of acrylate having an alkyl group having 1 to 8 carbon atoms, and 6 to 20% of carbon monoxide.
% By weight, 0.5 to 3.5 parts by weight of an ethylene-based copolymer obtained by copolymerizing 0 to 20% by weight of another vinyl monomer, and (B) a maleimide-modified styrene having a maleimide content of 3 to 30% by weight. The present invention provides a heat-resistant styrene resin composition comprising 100 parts by weight of a resin, and further, based on the maleimide-modified styrene resin (B), (C) polysiloxane 50 to 3
000ppm or ethylenebisstearylamide 1000 to 20000
A heat-resistant styrene resin composition containing ppm is provided.

A resin composition of 90 to 96% by weight of ABS resin and 4 to 10% by weight of ethylene-butyl acrylate-carbon monoxide copolymer is described in USP 4,985,497. -It is stated that the addition of carbon monoxide copolymer can improve the Izod impact strength without significantly impairing the rigidity and heat distortion temperature of the ABS resin. However, this specification does not describe a maleimide-modified styrene resin, and does not describe the problems of surface impact strength and stretch ratio. Also US
P 4,985,497 discloses that addition of ethylene-butyl acrylate-carbon monoxide copolymer in an amount of 4 to 10% by weight based on the total amount of ABS resin does not impair the decrease in rigidity and heat distortion temperature. Have been described. However, when the present inventors mixed the maleimide-modified styrene resin (B) and the acrylate-carbon monoxide-based copolymer (A) having an ethylene-alkyl group having 1 to 8 carbon atoms, ethylene-carbon number 1
The amount of the acrylate-carbon monoxide-based copolymer (A) having 8 to 8 alkyl groups is changed to maleimide-modified styrene resin.
It was found that if the amount is not less than 3.5% by weight relative to (B), the decrease in rigidity and heat resistance becomes clear, and there is a large limit from a practical point of view.

The ethylene copolymer as the component (A) of the present invention comprises 40 to 90% by weight of ethylene, 15 to 40% by weight of an acrylate having an alkyl group having 1 to 8 carbon atoms, and 6 to 20% of carbon monoxide.
% By weight, if necessary, other vinyl monomer (V ₀ ) 0-20
It can be produced by copolymerization with a high-pressure radical polymerization method together with wt%. Examples of the acrylate having an alkyl group having 1 to 8 carbon atoms used in the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate,
Examples thereof include n-octyl acrylate, and n-butyl acrylate is particularly preferable. Other vinyl monomers (V ₀ ) used in the present invention include methyl methacrylate,
Typical examples are vinyl acetate, maleic anhydride, dibutyl fumarate, methacrylic acid, acrylic acid and glycidyl methacrylate. (A) The amount of ethylene in the component
If it is less than 40% by weight, the surface impact strength, rigidity and heat resistance will be unsatisfactory, and if it exceeds 90% by weight, the surface impact strength will be unsatisfactory. Further, when the amount of the acrylate having an alkyl group having 1 to 8 carbon atoms is less than 15% by weight, the surface impact strength becomes unsatisfactory, and when it exceeds 40% by weight, the surface impact strength, rigidity and heat resistance become unsatisfactory. Further, if the alkyl group of the acrylate has 9 or more carbon atoms, the surface impact strength becomes unsatisfactory.
If the amount of carbon monoxide is less than 6% by weight, the surface impact strength becomes unsatisfactory, and if it exceeds 20% by weight, the surface impact strength, rigidity and heat resistance become unsatisfactory.

The melt index of the ethylene copolymer as the component (A) is 0.1 to 100 at a temperature of 190 ° C. and a load of 2.16 kg.
A range of g / 10 minutes is preferred. The component (A) is the component (B).
0.5 to 3.5 parts by weight are used for 100 parts by weight. Here, if the amount of the component (A) is less than 0.5 parts by weight, the surface impact strength and the stretch ratio are hardly improved, and if it exceeds 3.5 parts by weight, the rigidity and the heat resistance are remarkably deteriorated, so that there are large restrictions on the application. Become.

The maleimide-modified styrene resin which is the component (B) of the present invention includes styrenes (S ₁ ) 50 to 80% by weight, maleimides (M ₁ ) 5 to 35% by weight, acrylonitrile 0 to 40% by weight, and other components. It is produced by mixing a copolymer composed of 0 to 35% by weight of a vinyl monomer (V ₁ ) and a graft rubber described below. As styrenes (S ₁ ) used here,
Styrene, alpha methyl styrene, para methyl styrene, tribromo styrene dibromo styrene, etc. are mentioned, Styrene and / or alpha methyl styrene are preferable. The maleimides (M ₁ ) are preferably N-substituted maleimides, such as phenylmaleimide, 2-methylphenylmaleimide, 2,4-dimethylphenylmaleimide,
2-Chlorophenylmaleimide, 2,4,6-tribromophenylmaleimide, isopropylmaleimide, cyclohexylmaleimide and the like can be mentioned, and phenylmaleimide is particularly preferable from the viewpoints of cost and performance. Further, as the other vinyl monomer (V ₁ ) used here, methyl methacrylate, methacrylonitrile, methyl acrylate, dimethyl fumarate, dimethyl itaconate, maleic anhydride and the like are typical.

The above graft rubber is obtained by adding styrenes (S ₂ ), maleimides (M ₂ ), acrylonitrile and other vinyl monomers (V ₂ ) to a butadiene rubber latex and carrying out graft polymerization. System rubber 30
-80% by weight and 70 to 20% by weight of a styrene (S ₂ ) -maleimide (M ₂ ) -acrylonitrile copolymer. The butadiene rubber in this case is polybutadiene or butadiene 50% by weight or more and other vinyl monomers such as styrene, acrylonitrile, methyl methacrylate,
It is a copolymer with butyl acrylate and the like. The butadiene rubber is particles, and the particle diameter of the butadiene rubber particles is 0.2 to 0.5 μm on a weight average, and 90% by weight or more has a particle size distribution of 0.05 to 2 μm. Usually used. Styrenes in this case (S ₂ )
As the styrenes (S ₁ ), those similar to the styrenes (S ₁ ) can be used, and as the maleimides (M ₂ ), those similar to the maleimides (M ₁ ) can be used. Also, other vinyl monomer (V ₂ ) is methyl methacrylate,
Typical examples are methacrylonitrile, maleic anhydride, diethyl maleate, and methacrylic acid. Here, styrenes (S _2), a total styrenes for the maleimides (M _2), acrylonitrile and other vinyl monomer (V ₂₎ (S ₂₎
Is 50 to 80% by weight, and the ratio of maleimides (M ₂ ) is 0 to
The proportion of acrylonitrile is preferably 35% by weight, the proportion of acrylonitrile is 0 to 40% by weight, and the proportion of other vinyl monomer (V ₂ ) is preferably 0 to 35% by weight.

The content of maleimides contained in the maleimide-modified styrene resin (B) used in the present invention is 3 to 30% by weight. If the content of maleimides is less than 3% by weight, the heat resistance will be insufficient, and if it exceeds 30% by weight, the impact strength will be insufficient. Can be used in the present invention
(C) Polysiloxane means the following formula

[0012]

[Chemical 1]

(Herein, R represents a methyl group, a phenyl group or a hydrogen atom) and a polymer having a skeleton represented by the formula, and polydimethylsiloxane in which all R 2 are methyl groups, and methyl as R 3. Groups having both a phenyl group and a phenyl group, polymethylhydrogensiloxane having both a methyl group and a hydrogen atom as R, and modified polysiloxanes having various substituents at the molecular ends or in the middle of these polysiloxanes. For example, those having a group such as an amino group, a hydroxyl group, a carboxyl group, a mercapto group, an epoxy group, a polyoxyethylene group and a polyoxypropylene group are preferable, and polydimethylsiloxane is particularly preferable. The polysiloxane preferably has a viscosity at 25 ° C. of 100 to 60,000 centistokes. The amount of polysiloxane added is 50 to 3000 ppm based on the maleimide-modified styrene resin (B).
Especially, 100 to 2000 ppm is preferable. In this case, if the addition amount of polysiloxane is less than 50 ppm, the effect of adding polysiloxane is not clear, and if it exceeds 3000 ppm, the rigidity is remarkably reduced.

The amount of ethylenebisstearylamide that can be used in the present invention is 1000 to 20000 ppm, especially 2000 to 1500, based on the maleimide-modified styrene resin (B).
0 ppm is preferred. In this case, when the amount of ethylenebisstearylamide added is less than 1000 ppm, the effect of improving the surface impact strength is poor, and when it exceeds 20,000 ppm, the rigidity is significantly reduced. The polysiloxane and the ethylenebisstearylamide may be used in combination, and the amount of the combination used is the same as described above.

The heat-resistant styrene resin composition of the present invention is usually produced by melt-mixing the components (A) and (B) and, if necessary, the component (C) with an extruder, a kneader, a roll or the like. In carrying out the present invention, a butadiene rubber is dissolved in a mixed monomer of styrene and acrylonitrile or a mixed monomer in which methyl methacrylate, alphamethylstyrene, phenylmaleimide, etc. are further dissolved, and solution polymerization, bulk polymerization, bulk suspension is carried out. A salami type styrene resin obtained by polymerization by a method such as polymerization may be mixed and used with the heat resistant styrene resin composition of the present invention. In that case, the addition amount of this salami type styrene resin is the same as that of the present invention.
Usually, 200% by weight or less is used based on the component (B).

Known additives such as flame retardants, reinforcing fibers, fillers, antistatic agents, fluidity improvers, antioxidants, weather resistance improvers, lubricants and colorants are added to the heat resistant styrene resin composition of the present invention. The agent may be added, and various polymers such as polycarbonate, vinyl chloride resin, methyl methacrylate resin, polyamide resin, polyester resin, polyphenylene ether resin and the like may be added together with various known compatibilizers as necessary. it can.

[0017]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, the measuring method in the following examples is the molding temperature 2
Using a test piece molded at 50 ° C, the surface impact strength was determined by a falling ball impact test, and the test piece used was a square piece with a side length of 4.0 cm and a thickness of 3.4 mm. The weight weight was 3 kg and the impact diameter was 16 mm. The result was expressed by the drop height at which the test piece breaks by 50%.
Also, Izod impact strength is ASTM D-256, unit is kg / c
m ² , tensile strength and draw ratio were according to ASTM D-638, units were kg / cm ² and%, respectively, and heat distortion temperature was according to ASTM D-648 (without annealing). The melt index is measured according to ASTM D-1238, and the unit is g / 10 minutes. Unless otherwise specified, all parts and% are expressed on a weight basis.

Example 1 74 parts of a copolymer having a composition of 68% styrene, 7% phenylmaleimide, 25% acrylonitrile, a melt index of 0.8 measured at 200 ° C. and a load of 5 kg, and a weight average as a graft rubber. Particle size 0.32 μm and 0.05
The content of polybutadiene such as 99% by weight of particles having a particle size of up to 2.0 μm is 65%, and the composition of the grafted copolymer is 72% styrene and 28% acrylonitrile. With a content rate of 35% 26
100 parts of a maleimide-modified styrene resin with a phenylmaleimide content of 5.2%, and a composition of about ethylene.
66%, butyl acrylate about 22%, carbon monoxide about 12% and an ethylene copolymer having a melt index of 8 measured at a load of 2.16 kg and a temperature of 190 ° C. were mixed by an extruder to form pellets. In this case, the amount of ethylene copolymer was changed to 0, 1, 3, 5 parts. As additives, 0.1 part of the phenolic antioxidant Irganox 1076 manufactured by Ciba Geigy, 0.3 parts of trinonylphenyl phosphite, 0.1 parts of distearyl thiodipropionate were used.
Parts, and 0.1 part of calcium stearate. Then, the surface impact strength, the Izod impact strength, the tensile strength almost representing the rigidity, the stretching ratio, and the heat distortion temperature were measured. The measurement results are shown in Table 1.

[0019]

[Table 1]

Note) *: The improvement rate represents the improvement rate as compared with Experiment No. 1 in which the ethylene copolymer was not added. From the above results, the amount of ethylene copolymer added was 1 part and 3 parts.
The surface impact strength of each part is 27 compared with the experiment number 1.
% And 63%, and the stretching ratio was 44% and 67%, respectively, which are greatly improved. However, in view of the value of Izod impact strength, the improvement due to the addition of the ethylene-based copolymer is small, and the effect is lost.
Also, it is understood that when the amount of the ethylene copolymer added is 5 parts (Experiment No. 4), the tensile strength and the heat distortion temperature are considerably lowered.

Example 2 When used in Example 1 and 74 parts of a copolymer having a composition of 58% styrene, 19% phenylmaleimide, 23% acrylonitrile and a melt index of 0.5 measured at 200 ° C. and a load of 5 kg. Using 100 parts of a maleimide-modified styrene resin having a phenylmaleimide content of 14% by mixing 26 parts of the same graft rubber, 2 parts of the same ethylene copolymer as used in Example 1 and the same additives as in Example 1 were used. , And mixed with an extruder to form pellets. Next, physical properties were measured in the same manner as in Example 1. As a result, the surface impact strength was 50 cm, the Izod impact strength was 12, the tensile strength was 420, the stretching ratio was 12, and the heat distortion temperature was 110.
It was ℃. On the other hand, the result of the same experiment without adding the ethylene copolymer (comparative example) shows a surface impact strength of 35 cm.
The Izod impact strength was 11, the tensile strength was 430, the stretching ratio was 9, and the heat distortion temperature was 111 ° C.

Example 3 Example 1 except that 0.05 part of polydimethylsiloxane having a viscosity of 500 centistokes at 25 ° C. was added.
Experiments were performed in the same manner as Experiment No. 1 and Experiment No.
In the case corresponding to the experiment number 1 (comparative example), the results are a surface impact strength of 50 cm, an Izod impact strength of 22, a tensile strength of 435, a stretching ratio of 9, and a heat deformation temperature of 93 ° C., and an experiment number of 3 (invention example). The result in the case of conforming to is that the surface impact strength is 100 cm or more,
The Izod impact strength was 24, the tensile strength was 420, the stretching ratio was 18, and the heat distortion temperature was 92 ° C.

Example 4 Experiments were conducted in the same manner as Experiment No. 1 and Experiment No. 3 of Example 1 except that 1.0 part of ethylenebisstearylamide was added. The result of the case corresponding to the experiment number 1 (comparative example) is a surface impact strength of 65 cm, an Izod impact strength of 23, a tensile strength of 430, a stretching ratio of 10 and a heat deformation temperature of 93 ° C., and a case of corresponding to the experiment number 3. The result of (Example of the present invention) is the surface impact strength.
The Izod impact strength was 25, the tensile strength was 410, the stretching ratio was 21, and the heat distortion temperature was 110 ° C. From the results of Example 3 and Example 4, it can be seen that when polydimethylsiloxane or ethylenebisstearylamide is used in combination with the ethylene-based copolymer, the effect of further improving the surface impact strength and the draw ratio is further improved.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location (C08L 25/08 83:04)

Claims (2)

[Claims] 1. (A) 40 to 90% by weight of ethylene, 1 to 8 carbon atoms
15-40% by weight of acrylate having alkyl group, 6-20% by weight of carbon monoxide, 0-20% by weight of other vinyl monomer
Ethylene copolymer obtained by copolymerizing 0.5 to 3.5
A heat-resistant styrene resin composition comprising 100 parts by weight of (B) a maleimide-modified styrene resin having a maleimide content of 3 to 30% by weight. 2. A heat-resistant styrene resin composition according to claim 1, which further comprises (C) polysiloxane (50 to 3000 ppm) or ethylenebisstearylamide (1000 to 20000 ppm) based on the maleimide-modified styrene resin (B). object.