JPH0742382B2 - Rubber-modified styrene resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber-modified styrenic resin composition having excellent high-speed injection moldability, heat resistance and impact resistance.

[Problems to be Solved by Conventional Techniques and Inventions] Rubber-modified styrenic resins are widely used as materials for various molded containers because they have excellent moldability and shock resistance.

However, since this rubber-modified styrene resin has low fluidity, it is difficult to perform injection molding at high speed.

Therefore, in an aromatic monovinyl polymer obtained by mixing and polymerizing a rubber-like substance and an aromatic monovinyl polymer, a rubber-modified styrene-based resin composition containing a rubber-like substance at a specific ratio and mineral oil is added. It has been proposed (JP-A-60-192755).

However, in the present invention, although the effect of improving the fluidity is remarkable, the heat resistance is lowered and the balance of these substances is poor.

An object of the present invention is to solve these conventional drawbacks and to provide a rubber-modified styrene-based resin composition having excellent high-speed injection moldability, heat resistance and impact resistance.

[Means for Solving the Problems] That is, the present invention is a rubber-modified styrene-based resin composition containing a rubber-like polymer as dispersed particles, wherein (A) the rubber-like polymer content is 5 to 11% by weight. And (B) the resin phase aromatic monovinyl polymer has an intrinsic viscosity [η] of 0.40 to 0.60.
dl / g, (C) Mineral oil content is 4.0% by weight
The content of (D) the lubricant is 50 to 20,000 ppm by weight of at least one of higher fatty acids or metal salts of higher fatty acids, and (E) the residual aromatic monovinyl monomer content is 2000 ppm by weight or less. And the total content of the dimer and trimer of (F) aromatic monovinyl monomer is 0.6.
A rubber-modified styrene-based resin composition having a content of not more than wt% is provided.

The present invention is a rubber-modified styrene-based resin composition containing a rubber-like polymer as dispersed particles, which is basically obtained by polymerizing a rubber-like polymer and an aromatic monovinyl monomer. In the present invention, (A) to (F)
It is necessary to meet the requirements of.

The rubber-like polymer used in the present invention is obtained by solution polymerization with a so-called low-cis polybutadiene rubber having a cis-1,4 content of 25 to 45% obtained by solution polymerization with a lithium-based catalyst and a Ziegler-based catalyst. Cis 1,4 content is 9
Among the so-called high cis polybutadiene rubbers having a content of 0% or more, at least one kind or two or more kinds can be used in combination. In addition to these polybutadiene rubbers,
It may contain a copolymer of 1,3-butadiene and a compound copolymerizable therewith.

In the present invention, it is necessary that the content of the rubbery polymer (A) is 5 to 11% by weight, preferably 5.5 to 10% by weight. When the content of the rubber-like polymer is less than 5% by weight, practical strength is not sufficient, and when it exceeds 11% by weight, the fluidity of the resin composition is impaired and the viscosity becomes high at the time of production, which is not preferable. . The swelling index of this rubbery polymer with toluene is preferably in the range of 9 to 13. If it is out of this range, the impact resistance is lowered. Further, the gel amount is preferably in the range of 25 to 35. When the gel amount is 25 or less, the impact resistance decreases, and when the gel amount is 35 or more, the fluidity decreases. The method of obtaining the swelling index and the gel amount will be described later.

The rubber-like polymer is contained in the resin composition as dispersed particles, and the average rubber particle diameter is preferably in the range of 1.0 to 5.0 μm.

Next, in the present invention, the intrinsic viscosity [η] of the aromatic monovinyl polymer as the resin phase (B) is required to be 0.40 to 0.60 dl / g, preferably 0.45 to 0.55 dl / g. [Η] is 0.
When it is less than 40 dl / g, impact resistance such as Izod strength is lowered, while when [η] exceeds 0.60 dl / g, the fluidity of the resin composition is deteriorated, which is not suitable.

The measuring method of the intrinsic viscosity [η] is as follows.

The resin phase is dissolved in toluene and measured at 30 ° C. by an ordinary method using an Ubbelohde viscometer. At this time, the resin phase was previously
The resin composition is dissolved in toluene, and the gel phase containing the rubber-like polymer is separated by a centrifuge and dried.

The aromatic monovinyl polymer is obtained by polymerizing an aromatic monovinyl monomer, where the aromatic monovinyl monomer is styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, 2, 4-dimethylstyrene,
Nuclear alkyl-substituted styrenes such as ethylstyrene, p-tert-butylstyrene, α-methylstyrene, α-methyl-p
Examples include α-alkyl-substituted styrene such as methylstyrene.

Further, a monomer other than the aromatic monovinyl monomer can be used together. Specific examples include methacrylic acid esters such as methyl methacrylate; acrylic acid esters; maleic anhydride; acrylonitrile. When a monomer other than the aromatic monovinyl monomer is used in combination, the amount used is
It is 40% by weight or less, preferably 15 to 35% by weight, based on the total monomers.

Further, in the present invention, it is necessary to contain mineral oil, and it is necessary that the content of (C) mineral oil is 4.0% by weight or less, preferably 3.5 to 0.1% by weight. Here, if the content of the mineral oil exceeds 4.0% by weight, the rigidity of the resin composition is lowered and the heat resistance is also extremely lowered, which is not preferable.

As the above mineral oil, various kinds can be mentioned, but preferably, the initial distillation temperature of 2.5% by weight measured with ASTM D 1160 (10 mmHg) is in the range of 190 to 290 ° C.

Further, in the present invention, it is necessary to contain a specific amount of a specific lubricant. That is, as the (D) lubricant, at least one of higher fatty acids or metal salts of higher fatty acids is used.
50-20,000 ppm by weight of seed, preferably 100-18,000 pp
It is necessary to contain m. Here, if the content is less than 50 ppm by weight, residual strain is large in injection molding and impact resistance is reduced, which is not preferable. On the other hand, 20,0
When it exceeds 00 ppm by weight, it is not preferable because productivity is significantly reduced due to stains due to adhesion of an oily substance to a mold or a molded product during high-speed injection molding.

The higher fatty acid is a general term for linear saturated monocarboxylic acids having about 12 to 42 carbon atoms, and examples thereof include lauric acid, myristic acid, valmitic acid, stearic acid, behenic acid, and montanic acid. Metals of these metal salts include lithium, sodium, potassium, magnesium, calcium, aluminum and zinc, and typical metal salts of higher fatty acids include magnesium stearate, aluminum stearate, calcium stearate and zinc stearate. And so on.

Next, in the present invention, the content of the residual aromatic monovinyl monomer (E) is required to be 2,000 ppm by weight or less, preferably 1500 ppm by weight or less. If the content of the residual monomer exceeds 2,000 ppm by weight, it adheres to a mold, an injection-molded product or the like as an oily substance during high-speed injection molding, which is not preferable.

Further, in the present invention, it is necessary that the total content of the dimer and trimer of (F) aromatic monovinyl monomer is 0.6% by weight or less, preferably 0.5% by weight or less. If the total content of the dimer and trimer exceeds 0.6% by weight, it adheres to a mold, an injection-molded product or the like as an oily substance during high-speed injection molding, which is not preferable.

The content of mineral oil, the content of residual aromatic monovinyl monomers, the total content of dimers and trimer oligomers of aromatic monovinyl monomers, etc. can be analyzed by gas chromatography. it can.

The rubber-modified styrenic resin composition of the present invention as described above can be produced by polymerizing a styrenic monomer by a bulk polymerization method or a bulk suspension polymerization method in the presence of a rubbery polymer. .

The polymerization conditions are not particularly limited and may be carried out by a conventional method, but it is preferable to use an organic peroxide as a polymerization initiator. When this organic peroxide is used as a polymerization initiator, it is preferable because it has a high gel amount, is excellent in impact resistance, and can suppress the formation of oligomers of dimers and trimers. It is also effective to use a chain transfer agent during the polymerization.

To obtain the intrinsic viscosity [η] specified in the present invention,
It is necessary to appropriately select and adjust the feed rate, the polymerization temperature, the type and amount of the organic peroxide or the type and amount of the chain transfer agent.

Examples of the above organic peroxides include dialkyl peroxides, peroxydicarbonates, peroxyesters and the like. The chain transfer agent is
It is preferable to add it after forming rubber particles (phase transition), and examples thereof include mercaptans and α-methylstyrene linear dimer.

On the other hand, lubricants such as mineral oils and higher fatty acids to be contained in the present invention are added in the raw materials or during the polymerization as long as they do not impair the dissolution of the polymerization product from the rubbery polymer and the aromatic monovinyl monomer. be able to. Further, it can be dry blended with pellets. The content of the residual aromatic monovinyl monomer can be adjusted by the degree of vacuum in the vacuum devolatilizer, the feed rate, and the heating temperature in the bulk polymerization.

Further, the resin composition of the present invention may contain dyes / pigments, if necessary.
Additives such as fillers, antioxidants and antistatic agents can be added.

EXAMPLES Next, the present invention will be described in more detail by way of examples. The methods for measuring physical properties are shown below.

(1) Average rubber particle size (D _s ) An ultrathin section of the resin composition was taken and photographed with a transmission electron microscope (magnification: 10,000 times).
It was determined by measuring the particle size of 2,000 particles. The major axis diameter a and the minor axis diameter b of the dispersed particles in the electron micrograph were measured, and the average particle diameter was determined by the following formula.

Average rubber particle diameter D _s = Σn _i D _i ³ / Σn _i D _i ² (μm) (where n _i is the number of dispersed particles having a particle size D _i ) (2) Gel amount Resin composition Pellets (2g) in toluene solvent (200ml)
Dispersed in. This solvent dissolves the aromatic monovinyl polymer in the resin phase and disperses it in the rubber polymer phase (rubber phase).
Left. The rubber phase was separated from the dispersion as a gel using a centrifuge and dried in a vacuum dryer at 60 ° C for 8 hours.
A dry gel was obtained, and the gel amount was calculated by the following formula.

(3) Swelling index The weight of the wet gel immediately after centrifugation in (2) above was measured and determined by the following formula.

(4) Remaining monomer content and residual oligomer content by gas chromatography (5) Melt index (MI) according to ISO R1133 (200 ° C, load 5 kg) (6) Heat distortion temperature (HDT) according to JIS K 6871 (7) Izod impact strength According to JIS Z 7110 (notched) (8) Tensile strength and elongation According to ASTM D 638 (9) Adhesion time of oily substance to mold or molded product Molding temperature 280 ° C, cycle time 6 seconds In an inverted conical cup-shaped container (bottom diameter 45 mm, top diameter 55 mm, height 55 mm, wall thickness 0.5 mm)
This is the time until the oily substance adhered to the surface of the mold or the molded product is visually confirmed when is rapidly molded.

Example 1 Low-cis polybutadiene rubber (Asahi
Made by Kasei Kogyo Co., Ltd., product name Asaprene 700A) 6.2 layers
Parts, styrene 88.8 parts by weight, ethylbenzene 5.0 parts by weight
100 parts by weight of a mixture consisting of
Su (tertiary butyl peroxy) 3,3,5-trimethylcyclo
0.040 parts by weight of hexane and n-dodecyl as a chain transfer agent
0.03 parts by weight of mercaptan and antioxidant (Ciba Geigy
Company name, Irganox 1076) 0.070 parts by weight added
E, continuous to the first polymerization tank with a capacity of 13 maintained at 117 ° C
Was supplied to carry out polymerization.

Then, with respect to this polymer, chain at a rate of 0.020 per hour
Addition of n-dodecyl mercaptan as a transfer agent
Liquid transfer to the second polymerization tank of 19 and then to the third polymerization tank of volume 20
Then, after continuing the polymerization at a temperature of 120 to 180 ℃, 2.25% per hour
Combined mineral oil (made by Idemitsu Kosan Co., Ltd., trade name Daphne
-Mechanic oil KP-32) was added. Further devolatilization
Remove the volatile components with the equipment and pelletize the rubber-modified rubber.
A styrene resin was obtained.

The solid content before devolatilization was 90% by weight. The rubbery polymer content and the mineral oil content were determined by calculating the charged content from the solid content before devolatilization.

0.10 parts by weight of stearic acid was added as a lubricant to the rubber-modified polystyrene resin, and the mixture was kneaded with an extruder to prepare a resin composition. This was injection-molded and the physical properties of the molded product were measured. The results are shown in Table 1.

Example 2 In Example 1, the rubbery polymer was 7.0 parts by weight, styrene was 89.6 parts by weight, the polymerization initiator was 0.030 parts by weight, the chain transfer agent was 0.010 parts by weight, and the temperature of the first polymerization tank was 121 ° C. , The amount of chain transfer agent added to the second polymerization tank is 0.005 per hour,
The same procedure as in Example 1 was performed except that the mineral oil supply rate was 0.45 per hour. The results are shown in Table 1.

Example 3 In Example 1, the rubber-like polymer was treated with low cis polybutadiene.
(Made by Asahi Kasei Corp., trade name Jien NF35A
S) 8.1 parts by weight, styrene 90.7 parts by weight, chain transfer agent 0.
033 parts by weight, the temperature of the first polymerization tank to 117 ℃, the second polymerization
Supply amount of chain transfer agent added to the tank is 0.027 per hour, Minera
The same as Example 1 except that the amount of oil supplied was 2.7 per hour.
Like that. The results are shown in Table 1.

Example 4 In Example 1, as a rubbery polymer, high cis poly
Tajien (Ube Industries, Ltd., trade name Ube Ball BR
15HB) 6.3 parts by weight, styrene 88.7 parts by weight, chain transfer agent
0.033 parts by weight was added to bring the temperature of the first polymerization tank to 117 ° C. and the second
Supply amount of chain transfer agent added to the polymerization tank was 0.024 per hour
Other than that, the same as in Example 1. The results are shown in Table 1.

Example 5 In Example 1, as a rubbery polymer, high cis poly
Tajien (Ube Industries, Ltd., trade name Ube Ball BR
15HB) 7.2 parts by weight, 87.8 parts by weight of styrene, chain transfer agent
Add 0.033 parts by weight, bring the temperature of the first polymerization tank to 117 ° C, and add the second
Supply amount of chain transfer agent added to the mixing tank was 0.023 per hour
Others were the same as in Example 1. The results are shown in Table 1.
You

Example 6 The procedure of Example 2 was repeated, except that 0.10 part by weight of zinc stearate was added as a lubricant in place of stearic acid. The results are shown in Table 1.

Example 7 The same as Example 2 except that 0.50 part by weight of zinc stearate was added as a lubricant in place of stearic acid. The results are shown in Table 1.

Example 8 Example 8 was repeated except that 1.50 parts by weight of zinc stearate was added as a lubricant in place of stearic acid. The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated, except that the supply amount of the chain transfer agent added to the second polymerization tank was 0.031 per hour. The results are shown in Table 1.

Comparative Example 2 In Example 1, the polymerization initiator was 0.030 parts by weight, the chain transfer agent was 0.010 parts by weight, and the temperature of the first polymerization tank was 121 ° C.
The amount of chain transfer agent added to the second polymerization tank is 0.001 per hour
The same procedure as in Example 1 was carried out except that The results are shown in Table 1.

Comparative Example 3 In Example 1, the rubbery polymer was mixed with low cis polybutadiene.
En (Made by Asahi Kasei Corporation, trade name Jien NF35AS)
3.8 parts by weight, 91.2 parts by weight of styrene, 0.033 of chain transfer agent
Parts by weight, the temperature of the first polymerization tank is set to 117 ° C., and the second polymerization tank is heated.
The amount of chain transfer agent to be added to 0.026 per hour
The same as Example 1 except that the amount of oil supplied was 2.7 per hour.
Like that. The results are shown in Table 1.

Comparative Example 4 In Example 1, 5.0 parts by weight of rubber-like polymer, 9 styrene
0.0 parts by weight, polymerization initiator 0.042 parts by weight, chain transfer agent 0.
020 parts by weight, the temperature of the first polymerization tank is 116 ° C., the second polymerization tank is added, the supply amount of chain transfer agent is 0.005 per hour, the supply amount of mineral oil is 6.75 per hour, and stearic acid is used as a lubricant instead of stearic acid. Example 1 was repeated except that 1,000 ppm of zinc was added. The results are shown in Table 1.

Comparative Example 5 In Example 1, 5.0 parts by weight of the rubber-like polymer, 90.0 parts by weight of styrene, 0.042 parts by weight of the polymerization initiator, 0.020 parts by weight of the chain transfer agent were used, and the temperature of the first polymerization tank was set to 116 ° C. Example 1 was repeated except that the amount of chain transfer agent added to the polymerization tank was 0.005 per hour, the amount of mineral oil was 6.75 per hour, and no lubricant was added. The results are shown in Table 1.

Comparative Example 6 The procedure of Example 1 was repeated except that 2.50 parts by weight of zinc stearate was added instead of stearic acid. The results are shown in Table 1.

Comparative Example 7 In Example 3, the polymerization initiator was 0.010 parts by weight, the chain transfer agent was 0.005 parts by weight, the temperature of the first polymerization tank was 128 ° C., and the amount of the chain transfer agent added to the second polymerization tank was 0.030 per hour. The same procedure as in Example 1 was carried out except that The results are shown in Table 1.

Comparative Example 8 Example 5 is the same as Example 5 except that no lubricant is added.
It carried out similarly to. The results are shown in Table 1.

Example 9 Example 2 was repeated except that magnesium stearate was used instead of stearic acid. The results are shown in Table 1.

Comparative Example 9 The same as Example 1 except that the amount of low cis polybutadiene rubber used was 10.8 parts by weight, the amount of styrene used was 84.2 parts by weight, and the amount of ethylbenzene used was 5.0 parts by weight. I did. The results are shown in Table 1.

Comparative Example 10 The procedure of Example 1 was repeated except that the residual monomer content was changed to 3,500 ppm by weight by changing the temperature condition of the devolatilization apparatus. The results are shown in Table 1.

[Effects of the Invention] According to the present invention, a rubber-modified polystyrene resin composition having excellent fluidity of resin during injection molding and excellent in practical strength such as heat resistance and impact resistance can be obtained.

Therefore, the rubber-modified polystyrene resin composition of the present invention can be widely and effectively used in fields such as electric appliances materials and sundries.

Claims (1)

[Claims] 1. A rubber-modified styrenic resin composition containing a rubber-like polymer as dispersed particles, wherein (A) the rubber-like polymer content is 5 to 11% by weight, and (B) the resin phase Intrinsic viscosity [η] of aromatic monovinyl polymer is 0.40-0.60dl / g
And (C) the mineral oil content is 4.0% by weight or less, and (D) as a lubricant, at least one of higher fatty acids or metal salts of higher fatty acids is added in an amount of 50 to 20,000 weight pp.
m, (E) residual aromatic monovinyl monomer content is 2000 ppm by weight or less, and (F) aromatic monovinyl monomer dimer and trimer total content is 0.6 wt. % Or less of a rubber-modified styrene resin composition.