JPH11343373A - Rubber modified styrene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber-modified styrene resin compsn. which does not undergo the degradation in impact strength or stiffness even when a flame retardant is compounded into the same. SOLUTION: In a rubber-modified styrene resin compsn. contg. a rubber- modified styrene resin which comprises a styrene resin as the matrix and rubbery polymer particles dispersed therein, the content of the styrene resin in the rubber-modified styrene resin is 80-90 wt.%, and the content of the rubbery polymer is 10-20 wt.%; and the rubbery polymer contains a group of small particles with a vol. average particle size of 0.6-1.2 μm and a group of large particles with a vol. average particle size of 2.6-5.0 μm, the content of the group of large particles being 30-90 wt.% based on the total amt. of the rubbery polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber-modified styrenic resin composition having an excellent balance between impact resistance and rigidity.

[0002]

2. Description of the Related Art High-impact styrene resins represented by high-impact polystyrene (HIPS) are excellent in moldability, rigidity and electric properties, and are therefore used in home electric appliances. Are used in various industrial fields including OA equipment parts. In such an industrial field, flame retardancy has been increasingly imparted to resin materials to be used from the viewpoint of safety.

[0003] In making a resin flame-retardant, a flame-retardant and a flame-retardant synergist for imparting flame-retardancy have conventionally been blended.
However, in general, in flame retardant formulations, there is a problem that if sufficient flame retardancy is to be obtained, the impact resistance is greatly reduced, and the high impact resistance originally provided by the impact resistant styrene resin is reduced. .

[0004] As a method of improving the decrease in impact resistance due to the addition of a flame retardant, a method of increasing the content of a rubbery polymer, a method of increasing a gel content, and the like are known. There is known a method for improving impact resistance by blending a butadiene copolymer impact modifier. However, when these methods for improving impact resistance are applied, problems such as deterioration of heat resistance, fluidity, and moldability, deterioration of the appearance of a molded product, and the like are caused, rigidity is reduced, and elastic modulus is also reduced.

In addition to these prior arts, many proposals have been made to improve the properties of high impact polystyrene. Japanese Patent Publication No. 41177/1994 discloses a method for producing impact-resistant polystyrene containing small particles having a volume average particle diameter of 0.5 to 1.5 μm and large particles having a volume average particle diameter of 4 to 10 μm. There is a problem of low. JP-A-4-65
No. 451 discloses an impact-resistant polystyrene containing small particles having an average particle diameter of 0.6 to 0.8 μm and large particles having an average particle diameter of 1.2 to 3.5 μm. There is a problem that is difficult. JP-A-3-1190
No. 13 discloses high-impact polystyrene containing small particles having a volume average particle diameter of 0.2 to 0.6 μm and large particles having a volume average particle size of 2.5 to 5 μm. There is a problem that it is difficult. JP-A-5-32848
The publication discloses small particles of less than 0.6 μm and 0.8-4.0.
Although high-impact polystyrene comprising large particles of μm is disclosed, there is a problem that it is difficult to maintain strength when a flame retardant is added.

The present invention provides a rubber-modified styrenic resin composition having a good balance of impact resistance and rigidity and capable of obtaining a molded article having a small decrease in impact resistance even when a flame retardant is blended. The purpose is to provide.

[0007]

According to the present invention, there is provided a rubber-modified styrenic resin composition containing a rubber-modified styrenic resin in which a styrenic resin forms a matrix and rubbery polymer particles are dispersed therein. In the rubber-modified styrene resin, the content of the styrene resin is 80 to 90% by weight, the content of the rubbery polymer is 10 to 20% by weight, and the volume average particle diameter of the rubbery polymer is 0.1 to 0.2%. 6-1.2
μm small particle group and volume average particle diameter of 2.6 to 5.0 μm
m, having a large particle size group, wherein the content of the large particle size group is 30 to 90% by weight based on the total amount of the rubbery polymer.

In the present invention, the volume average particle size is
Using an ultra-thin section of a rubber-modified styrenic resin molded article dyed with osmic acid, the transmission electron micrograph was taken,
It is a value calculated by measuring the circle-equivalent particle diameter of 1000 rubber-like polymer particles and using the following equation. Volume average particle size ^{_{= (Σn i D i 4)}} / (Σn i D i 3) [ wherein, n _i denotes the number of the rubber-like polymer particles having equivalent circle diameter D _i (μm). ]

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber-modified styrenic resin used in the present invention is a polymer in which rubber-like polymer particles are dispersed in a matrix made of an aromatic vinyl polymer.

The polymer constituting the matrix is obtained by polymerizing at least one aromatic vinyl monomer or at least one aromatic vinyl monomer and at least one vinyl group-containing monomer copolymerizable therewith. Can be obtained. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, 2,4-dimethylstyrene, and the like, and examples of the vinyl group-containing monomer include acrylic acid, methacrylic acid or esters thereof, and acrylonitrile. And the like.

Examples of the rubbery polymer constituting the dispersed particles include diene rubbers such as polybutadiene and poly (styrene-butadiene) and those obtained by (partially) hydrogenating the same.
Examples include isoprene rubber, chloroprene rubber, and acrylic rubber.

As a method for obtaining a rubber-modified styrenic resin, the above-mentioned vinyl monomer is graft-polymerized by general bulk polymerization, bulk suspension polymerization, solution polymerization, emulsion polymerization or the like in the presence of a rubber-like polymer. Can be mentioned.

The content of the styrene resin in the rubber-modified styrene resin is 80 to 90% by weight, preferably 83 to 90% by weight.
89% by weight, and the content of the rubbery polymer is 10 to 20%.
% By weight, preferably 11 to 17% by weight. When the content of the rubber-like polymer is 10% by weight or more, sufficient impact resistance can be imparted, for example, in the case of flame retardation, and when the content is 20% by weight or less, fluidity at the time of resin melting is reduced. Moderately,
The dispersibility of the flame retardant and the like can be improved, and the moldability of the composition can also be improved.

The rubbery polymer of the rubber-modified styrene resin mainly contains a small particle size group and a large particle size group within a predetermined particle size range. Here, "mainly containing a small particle size group and a large particle size group in a predetermined particle size range" means, for example, the particle size distribution on the horizontal axis and the content on the vertical axis. Are plotted, two significant peaks of a small particle diameter group having a volume average particle diameter of 0.6 to 1.2 μm and a large particle diameter group having a volume average particle diameter of 2.6 to 5.0 μm are as follows. And that the other particle size groups do not show a special peak (in other words, the presence of the rubbery polymer of the other particle size group within a range that does not impair the object of the present invention is not excluded). Is meant.

The small particle diameter group has a volume average particle diameter of 0.6 to
It is 1.2 μm, preferably 0.7 to 1.0 μm. When the volume average particle diameter is 0.6 μm or more, at the time of flame retardation, without impairing the development of impact resistance, 1.2 μm
When it is at most, the elastic modulus is improved, and it is particularly useful for imparting a balance between the elastic modulus and the impact resistance when a styrene-butadiene copolymer impact modifier is added.

The large particle size group has a volume average particle size of 2.6 to
It is 5.0 μm, preferably 2.6 to 4.0 μm. When it is 2.6 μm or more, the impact resistance at the time of flame retardation can be improved, and when it is 5.0 μm or less, the elastic modulus is improved, the fluidity at the time of melting is improved, and a flame retardant, etc. And the moldability of the composition can be improved.

The content of the large particle diameter group is 30 to 90% by weight, preferably 40 to 7% by weight, based on the total amount of the rubber polymer.
0% by weight. When the content is within the above range, impact resistance can be imparted at the time of flame retardation, the elastic modulus is further improved, and the impact improvement effect when a styrene-butadiene copolymer impact modifier is added is added. Can also be increased.

The content ratio (weight ratio) of the small particle size group to the large particle size group in the rubber-like polymer is preferably 70:30 to 10:90 in terms of raw materials, and particularly preferably 60:10 to 90:90. 40 to 30:70. When the content ratio of the small particle diameter group and the large particle diameter group is within the above range, impact resistance can be imparted at the time of flame retardation, further improving the elastic modulus, and improving the styrene-butadiene copolymer system impact. The effect of improving the impact when the agent is added can also be enhanced.

The total content of the small particle size group and the large particle size group in the rubbery polymer is not particularly limited as long as the object of the present invention can be achieved, but is 50% by weight or more. Is preferred.

The method for producing the rubber-modified styrene resin containing the small particle size group and the large particle size group as described above is not particularly limited. For example, the following two-step method is used. Can be obtained by applying. First,
General methods such as controlling the temperature at the time of polymerization, the stirring conditions at the time of polymerization, the amount of the initiator, the viscosity of the rubbery polymer, and the molecular weight distribution of the rubbery polymer during the production of the rubber-modified styrenic resin. Apply to control the particle size to the desired range. Next, a method of mixing and extruding separately polymerized resins (that is, a resin containing rubber-like polymer particles having different particle diameter ranges) to form a resin or a method of mixing separately polymerized resins is applied to achieve the desired purpose. To obtain a rubber-modified styrene resin. In addition,
A method of mixing separately polymerized polymerization liquids (that is, a polymerization liquid containing rubber-like polymer particles having different particle diameter ranges) during polymerization, or a method of using or combining a special rubber-like polymer is used. You can also.

The rubber-modified styrenic resin composition of the present invention may further contain a halogen-based flame retardant and a flame retardant synergist.

Examples of the halogen-based flame retardant include aromatic bromo compounds such as hexabromobenzene, decabromobenzene, pentabromotoluene, tetrabromodiphenyl ether, decabromodiphenyl ether, hexabromocyclodecane, tetrabromophthalic anhydride, and tetrabromobisphenol A. And one or more selected from halogenated alicyclic compounds such as perchlorocyclodecane and the like.

Examples of the halogen-based flame retardant synergist include at least one selected from antimony trioxide, antimony tetroxide, sodium antimonate, metal antimony, antimony trichloride and the like.

The compounding amount of the halogen-based flame retardant and the halogen-based flame retardant synergist is preferably 5 to 50 parts by weight based on the rubber-modified styrene resin.

The rubber-modified styrene resin composition of the present invention may further contain a non-halogen flame retardant and a flame retardant synergist.

Examples of the non-halogen flame retardant include one or more selected from phenyl group-containing compounds, phosphorus-containing compounds, boron-containing compounds and the like. As the phenyl group-containing compound, polyphenylene ether resins,
Novolak resins and the like can be mentioned. Examples of the phosphorus-containing compound include inorganic phosphates such as ammonium polyphosphate, organic phosphorus compounds such as red phosphorus and phosphate esters, and salts such as melamine phosphate and melamine pyrophosphate. The boron-containing compound may include boric acid, zinc borate and the like.

As the non-halogen flame retardant synergist, a triazine ring compound such as melamine can be used as a phosphorus flame retardant, and a metal oxide such as aluminum oxide;
Examples include hydrated metal compounds such as aluminum hydroxide and silicone resins such as polyorganosiloxane.

The compounding amount of the non-halogen flame retardant and the non-halogen flame retardant synergist is preferably 20 to 150 parts by weight based on the rubber-modified styrene resin.

The rubber-modified styrene resin composition of the present invention may further contain a styrene-butadiene copolymer impact modifier. Styrene-butadiene copolymer-based impact modifiers are generally commercially available styrene-butadiene copolymers in which the styrene and butadiene portions are diblock and multiblock, and are randomly copolymerized. Or a copolymer in which part or all of the butadiene moiety in these copolymers is hydrogenated.

The amount of the styrene-butadiene copolymer impact modifier is not particularly limited, but is preferably 0.1 to 20 parts by weight based on the rubber-modified styrene resin.

The rubber-modified styrenic resin composition of the present invention may contain ordinary additives as long as the effects of the present invention are not impaired.
Lubricants, stabilizers, coloring agents, antistatic agents, antioxidants, ultraviolet absorbers, fillers, and the like can be added.

[0032]

EXAMPLES Next, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to these examples and comparative examples. In the following examples, “%” and “parts” all represent “% by weight” and “parts by weight”. The measurement items in Examples of the present invention and Comparative Examples were evaluated by the following methods.

(1) Izod impact strength (kg · cm / cm ² )
Izod impact strength was measured according to JIS K7110. (2) Dupont impact strength (kg · cm) Dupont impact strength was measured according to JIS K7211. (3) Flexural modulus (kg / cm ² ) Flexural modulus is JIS K7
203. (4) Flame retardancy Evaluation of flame retardancy is UL-9 in the United States.
The measurement was performed in accordance with four standards.

Production Example 1 80.0 styrene monomer was placed in a completely stirred mixing tank reactor.
, Hi-cis polybutadiene rubber (Ube Industries, Ltd.)
Ubepol Z022) 10.0 parts, ethylbenzene 1
0.0 parts was charged and dissolved by stirring at 40 ° C. for 8 hours.
The temperature was raised to 130 ° C. with stirring to start the reaction. Polymerization was carried out at a temperature of 130 ° C. and stirring at 40 rpm for 2 hours.
m for 2 hours, temperature 150 ° C., stirring 10 rpm for 1 hour to carry out the reaction.
Using an extruder with a devolatilization function, unreacted monomer at 230 ° C,
Ethylbenzene was removed. The molten strand was cooled and cut to obtain a pellet-shaped rubber-modified styrenic resin.
The obtained rubber-modified styrene resin is referred to as HIPS-1. Table 1 shows the results of measuring the physical properties of the rubber-modified styrene resin.

Production Example 2 80.0 parts of styrene monomer, Hi-cis polybutadiene rubber (Ubepol 34HL, Ube Industries, Ltd.)
0 parts and 10.0 parts of ethylbenzene were charged into the same reactor as in Production Example 1, and stirred and dissolved at 40 ° C. for 8 hours. The temperature was raised to 130 ° C. with stirring to start the reaction. Temperature 130
After polymerization at 80 ° C. for 2 hours with stirring at 80 rpm, and the polymerization rate of the monomer became about 30%, the polymerization was carried out at 140 ° C. with stirring at 20 rpm.
The reaction was carried out by sequentially increasing the temperature for 1 hour at a temperature of 150 ° C. and stirring at 10 rpm, and at the time of a monomer polymerization rate of 81%, the same treatment as in Production Example 1 was performed to obtain a rubber-modified styrene resin. The obtained rubber-modified styrene resin is referred to as HIPS-2. Table 1 shows the results of measuring the physical properties of the rubber-modified styrene resin.

Production Example 3 80.0 parts of styrene monomer, Hi-cis polybutadiene rubber (Ubepol Z022, Ube Industries, Ltd.)
0 parts and 10.0 parts of ethylbenzene were charged into the same reactor as in Production Example 1, and stirred and dissolved at 40 ° C. for 8 hours. The temperature was raised to 130 ° C. with stirring to start the reaction. Temperature 130
The polymerization was carried out for 2 hours at 20 ° C. and stirring at 20 rpm, and the polymerization rate of the monomer became about 30%.
The reaction was carried out by sequentially raising the temperature for 1 hour at a temperature of 150 ° C. and stirring at 10 rpm, and at the time when the monomer polymerization rate was 80%, the same treatment as in Production Example 1 was performed to obtain a rubber-modified styrene resin. The obtained rubber-modified styrene resin is referred to as HIPS-3. Table 1 shows the results of measuring the physical properties of the rubber-modified styrene resin.

Production Example 4 80.0 parts of styrene monomer, Hi-cis polybutadiene rubber (Ubepol 13HB, Ube Industries, Ltd.)
0 parts and 10.0 parts of ethylbenzene were charged into the same reactor as in Production Example 1, and stirred and dissolved at 40 ° C. for 8 hours. The temperature was raised to 130 ° C. with stirring to start the reaction. Temperature 130
The polymerization was carried out for 2 hours at 20 ° C. and stirring at 20 rpm, and the polymerization rate of the monomer became about 30%.
The reaction was carried out by sequentially raising the temperature for 1 hour at a temperature of 150 ° C. and stirring at 10 rpm, and at the time when the monomer polymerization rate was 78%, the same treatment as in Production Example 1 was performed to obtain a rubber-modified styrene resin. The obtained rubber-modified styrene resin is referred to as HIPS-4. Table 1 shows the results of measuring the physical properties of the rubber-modified styrene resin.

[0038]

[Table 1]

Example 1 HIPS-1: 50 parts, HIPS-2: 50 parts, ethylene bistetrabromophthalimide (Albemar SAYTEX BT-93): 17 parts as a flame retardant, antimony trioxide (Guangdong) as a flame retardant synergist, etc. Mikuni Co., Ltd.):
5 parts, zinc stearate: 0.5 part were blended, and a twin screw extruder (Toshiba Machine Co., Ltd. IS100E-3A) was used at 220 ° C.
To obtain a composition. Table 2 shows the measurement results of the physical properties.

Example 2 A composition was obtained by kneading 40 parts of HIPS-3 and 60 parts of HIPS-4 with the flame retardant and flame retardant synergist of Example 1. Table 2 shows the measurement results of the physical properties.

Example 3 HIPS-3: 43 parts, HIPS-2: 43 parts, commercially available G
PPS (Daicel Styrol 2 of Daicel Chemical Industries, Ltd.)
0): 10 parts, styrene-butadiene copolymer (TR2000, Nippon Synthetic Rubber Co., Ltd.): 4 parts, the flame retardant of Example 1 and the flame retardant synergist were kneaded to obtain a composition. Table 2 shows the measurement results of the physical properties.

Example 4 HIPS-3: 34 parts, HIPS-4: 52 parts, commercially available G
PPS (Daicel Styrol 2 of Daicel Chemical Industries, Ltd.)
0): 10 parts, styrene-butadiene copolymer (TR2000, Nippon Synthetic Rubber Co., Ltd.): 4 parts, the flame retardant of Example 1 and the flame retardant synergist were kneaded to obtain a composition. Table 2 shows the measurement results of the physical properties.

Comparative Example 1 The flame retardant and the flame retardant synergist of Example 1 were kneaded with 100 parts by weight of HIPS-1 to obtain a composition. Table 2 shows the measurement results of the physical properties.

Comparative Example 2 HIPS-2: 100 parts by weight of the flame retardant and the flame retardant synergist of Example 1 were kneaded to obtain a composition. Table 2 shows the measurement results of the physical properties.

Comparative Example 3 HIPS-1: 86 parts, commercially available GPPS (Daicel Styrol 20 from Daicel Chemical Industries, Ltd.): 10 parts, styrene-butadiene copolymer (Nippon Synthetic Rubber Co., Ltd., TR200)
0): The flame retardant and the flame retardant synergist of Example 1 were kneaded in 4 parts to obtain a composition. Table 2 shows the measurement results of the physical properties.

Comparative Example 4 HIPS-2: 86 parts, commercial GPPS (Daicel Styrol 20, Daicel Chemical Industries, Ltd.): 10 parts, styrene-butadiene copolymer (Nippon Synthetic Rubber Co., Ltd., TR200)
0): The flame retardant and the flame retardant synergist of Example 1 were kneaded in 4 parts to obtain a composition. Table 2 shows the measurement results of the physical properties.

[0047]

[Table 2]

In Examples 1 and 3, the Izod impact strength and the flexural modulus are provided in a well-balanced manner, and have sufficient values. Also in Examples 2 and 4, the Izod impact strength and the flexural modulus are well-balanced, and have sufficient values. By adding the styrene-butadiene copolymer-based impact modifier, the DuPont impact strength also has a sufficient value. Obtained. In Comparative Example 1 (containing only the large particle size group), the Izod impact strength was sufficient, but the flexural modulus was low and the rigidity was insufficient. In Comparative Example 2 (containing only the small particle size group), the rigidity was high, but the impact strength was not a sufficient value. Comparative Example 3 using a styrene-butadiene copolymer-based impact modifier (containing only a large particle diameter group),
The same tendency is observed in Comparative Example 4 (containing only the small particle diameter group).

[0049]

The rubber-modified styrenic resin of the present invention contains a small particle diameter group and a large particle diameter group having different particle diameter ranges as rubber-like polymers, and therefore has a good balance of impact resistance and rigidity. Both properties do not deteriorate even when a flame retardant is added.

Claims (5)

[Claims] 1. A rubber-modified styrenic resin composition comprising a rubber-modified styrenic resin in which a styrenic resin forms a matrix and rubbery polymer particles are dispersed therein, wherein the styrene in the rubber-modified styrenic resin is The content of the system resin is 80 to 90% by weight, the content of the rubbery polymer is 10 to 20% by weight, and the rubbery polymer is a small particle having a volume average particle diameter of 0.6 to 1.2 μm. Group and a large particle diameter group having a volume average particle diameter of 2.6 to 5.0 μm, and the content of the large particle diameter group is 30 to 90 with respect to the total amount of the rubbery polymer.
A rubber-modified styrenic resin composition, characterized in that the composition is a weight percent. 2. The content ratio (weight ratio) between the small particle size group and the large particle size group in the rubbery polymer is 70: 3 in terms of raw material.
The rubber-modified styrenic resin composition according to claim 1, wherein the ratio is from 0 to 10:90. 3. The rubber-modified styrenic resin composition according to claim 1, further comprising a halogen-based flame retardant and a flame retardant synergist. 4. The rubber-modified styrenic resin composition according to claim 1, further comprising a non-halogen flame retardant and a flame retardant synergist. 5. The rubber-modified styrenic resin composition according to claim 1, further comprising a styrene-butadiene copolymer impact modifier.