JPH10110085A - Rubber-modified styrenic resin composition and molded article prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber-modified styrenic resin composition which not only has sufficient rigidity and impact resistance, but also is excellent in fluidity and thermal resistance, and further can be produced at a low cost, and provide articles prepared from the resin composition. SOLUTION: This rubber-modified styrenic resin composition has particles of a soft component containing a rubbery polymer dispersed in a continuous phase formed by a styrenic polymer which has a weight average molecular weight of 106,000 to 160,000. In synthesizing such a rubber-modified styrenic resin composition, use is made of a rubbery polymer having the following characteristics (a), (b) and (c): (a) the molecular weight distribution curve has a bimodal distribution, in which a low molecular weight side peak appears in the range between 10,000 and 60,000, and a high molecular weight side peak in the range between 300,000 and 600,000; (b) the toluene solution viscosity is 30 to 90cPs, as measured at a concentration of 5wt.% and at 25 deg.C; and (c) it is a high cis polybutadiene having a cis-1,4 bond content of 70% or more and less than 100%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive rubber-modified styrenic resin composition having sufficient rigidity and impact resistance, excellent fluidity and heat resistance, and a molded article using the composition. is there.

[0002]

2. Description of the Related Art A rubber-modified styrene resin composition comprising a styrene resin and soft component particles is a so-called high impact polystyrene (High Impact Polystyrene).
ren: HIPS). Such impact-resistant polystyrene has the rigidity of ordinary polystyrene,
It is useful as a resin having improved impact resistance while maintaining moldability. However, when a conventional resin is used for large-sized thin-wall molding such as a housing of a large TV, it is necessary to add a large amount of a plasticizer such as mineral oil to give sufficient fluidity to the resin. Heat resistance and rigidity were reduced. In addition, the use of a large amount of a plasticizer such as a mineral oil has disadvantages in that the molding cycle is prolonged and mold contamination is increased. As a method for improving fluidity while maintaining heat resistance, a technique of blending a hydroxyl group-containing aromatic phosphate and a compound having at least one functional group capable of hydrogen bonding with the hydroxyl group in one molecule (particularly, Japanese Unexamined Patent Publication (Kokai) No. 5-379420) discloses a technique (JP-A-6-157920) in which an organic compound having a plasticizing effect and a fat / gelling agent having a gelling ability for the organic compound are used in combination. However, in these methods, a sufficient fluidity improving effect is not obtained, and the cost of the resin composition increases because the compound used is relatively expensive, which is not preferable from an industrial viewpoint. Japanese Patent Publication No. 7-42382 discloses a method of improving the fluidity by lowering the viscosity of a continuous phase of a rubber-modified styrene resin composition.
The effect is not enough. Japanese Patent Publication No. 6-21135 discloses a rubber-modified styrenic resin composition using a rubbery polymer having a bimodal molecular weight distribution curve and a viscosity of 5 to 100 cps of a 5% by weight toluene solution measured at 25 ° C. However, fluidity, heat resistance and rigidity are not considered at all. No conventional rubber-modified styrenic resin composition satisfies all of fluidity, heat resistance, rigidity, and impact resistance.

[0003]

An object of the present invention is to provide an inexpensive rubber-modified styrene resin composition having sufficient rigidity and impact resistance, excellent fluidity and heat resistance, and the resin composition. It is to provide a molded article using a product.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have reached the present invention. That is, among the present invention, the first invention is that soft component particles containing a rubbery polymer are dispersed in a styrene resin forming a continuous phase, and the styrene resin has a weight average molecular weight of 106,000 to 160,000. A rubber-modified styrenic resin composition wherein the rubbery polymer used in synthesizing such a rubber-modified styrenic resin composition has the following properties (a), (b) and (c). The present invention relates to a rubber-modified styrenic resin composition characterized by the following. (A) The molecular weight distribution curve shows a bimodal distribution, with a low molecular weight peak between 10,000 and 60,000 and a high molecular weight peak between 300,000 and 600,000. (B) 5% by weight toluene solution viscosity measured at 25 ° C. is 3
It is 0 to 90 cps. (C) High cis polybutadiene having a cis 1,4 bond amount of 70% or more and less than 100%. Further, among the present invention, the second invention is the rubber modification according to the first invention, wherein the content of the rubbery polymer is 6 to 12 parts by weight based on 100 parts by weight of the styrene resin forming the continuous phase. It relates to a styrene resin composition. Further, among the present invention, a third invention relates to a molded article using the rubber-modified styrene resin composition of the first and second inventions.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given. As the styrene monomer used as a raw material of the rubber-modified styrene resin composition of the present invention, styrene is generally used, but α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene And other alkyl-substituted styrenes.

The weight average molecular weight of the styrene resin forming the continuous phase of the rubber-modified styrene resin composition of the present invention is 1
06000 to 160,000. Weight average molecular weight is 1
When it is less than 06000, the fluidity of the rubber-modified styrene resin composition is improved, but the rigidity and impact resistance are poor. When the weight average molecular weight exceeds 160,000, the balance between heat resistance and fluidity is poor.

Here, the weight average molecular weight was evaluated as follows. That is, about 0.5 g of the rubber-modified styrene resin composition is dissolved in a methyl ethyl ketone-methanol mixed solvent (volume ratio = 10/1). Next, a styrene-based resin portion forming a continuous phase and a soft component that is an insoluble component are separated by centrifugation, and a supernatant liquid other than the insoluble component is removed by decantation, and methanol 500 is removed.
The styrene-based resin part which forms a continuous phase is gradually settled into the ml while stirring. Glass filter (G
The styrene-based resin portion forming the continuous phase is filtered using S25), and methanol is removed by drying. The obtained dried sample was dissolved in tetrahydrafuran so as to have a concentration of 0.5 g / ml. The solution was analyzed using gel permeation chromatography (GPC) to evaluate the weight average molecular weight of the styrene resin forming the continuous phase. Here, this GPC is a UV detector.
It was equipped with a detector, and the weight average molecular weight was calculated by a calibration curve obtained using monodisperse polystyrene.

The rubbery polymer used in the present invention is
(A) the molecular weight distribution curve shows a bimodal distribution, the peak on the low molecular weight side is between 10,000 and 60000, the peak on the high molecular weight side is between 300000 and 600000, and (b) at 25 ° C. The measured 5% by weight toluene solution viscosity is 30 to 90 cps, and (c) high cis polybutadiene having a cis 1,4 bond content of 70% or more and less than 100%. If the molecular weight distribution curve does not show a bimodal distribution, or even if it has a bimodal distribution, if its peak does not exist within the above range, the rigidity and impact strength are poor. Also, cis 1,
(4) When low cis polybutadiene having a bonding amount of less than 70% is used, rigidity and impact strength are poor. Further, the viscosity of the 5% by weight toluene solution measured at 25 ° C. must be in the range of 30-90. If it is not within this range, the rigidity and impact strength are poor.

Here, the molecular weight distribution curve of the rubbery polymer was determined as follows. That is, about 0.15 g of the rubbery polymer is dissolved in 20 ml of tetrahydrafuran. Gel permeation chromatography (G
The solution was analyzed using (PC) to obtain a molecular weight distribution curve of the rubbery polymer. Here, this GPC is provided with a differential refractometer as a detector.

The viscosity of the 5% by weight toluene solution was measured by a conventional method using a B-type viscometer manufactured by Tokyo Keiki. In addition, the measurement of the cis 1, 4 bond amount is based on the Morero method.

The amount of the rubbery polymer used is in the range of 6 to 12 parts by weight based on 100 parts by weight of the styrene resin forming the continuous phase, and the rubber modified styrene resin composition satisfying the requirements of the present invention is Satisfies all of fluidity, heat resistance, rigidity and impact resistance. If the amount used is less than 6 parts by weight, the impact strength is not sufficient, and if it exceeds 12 parts by weight, the rigidity is low, which is not suitable for applications requiring rigidity.

Next, a method for producing the rubber-modified styrenic resin composition of the present invention will be described. The method for producing a rubber-modified styrene-based resin composition of the present invention comprises polymerizing the styrene-based monomer by a bulk polymerization method or a bulk / suspension two-stage polymerization method in the presence of the rubber-like conjugated diene-based polymer. Things. By adjusting the concentration of the rubber-like elastic material, the stirring speed, the temperature, the amount of the plasticizer, and the like during the polymerization reaction, a rubber-modified styrene resin composition satisfying the conditions of the present invention can be obtained. Further, the rubber-modified styrenic resin composition of the present invention is a rubber-modified styrenic resin composition satisfying the requirements of the present invention by mixing two or more rubber-modified styrenic resin compositions or styrene-based resin compositions. It can be a thing.

The rubber-modified styrenic resin composition of the present invention may optionally contain an antistatic agent, an antioxidant, an ultraviolet absorber, a heat stabilizer, silicone oil, a pigment, a dye, and the like.

The rubber-modified styrenic resin composition of the present invention can be molded using a commonly used molding machine. For example, there are an injection molding machine, an extrusion molding machine, a blow molding machine, and an injection blow molding machine.

The rubber-modified styrenic resin composition of the present invention has sufficient rigidity and impact resistance, is excellent in fluidity and heat resistance, and is inexpensive. It is suitably used in a wide range of fields utilizing its excellent features, for example, large injection molded articles such as large TV housings and toys.

[0016]

EXAMPLES Examples are shown below, but the present invention is not limited to these examples. The data shown in the examples was measured based on the following method. (1) Melt flow rate (fluidity): JIS K72
It measured according to 10. The temperature was 200 ° C and the load was 5
kgf. (2) Heat deformation temperature (heat resistance): Measured according to JIS K7207. (3) Izod impact strength (impact resistance): JIS K7
It was measured according to 110. The measurement temperature was 3.0 mm (thickness), notched, and the measurement temperature was 23 ° C. (4) Flexural modulus (rigidity): Measured according to JIS K7203. The measurement temperature was 23 ° C.

EXAMPLE 1 3.3 parts by weight of mineral oil was added to 100 parts by weight of styrene in an autoclave with a stirrer of a complete mixing type having an internal volume of 20 liters, the cis-1,4 bond amount was 93%, and the molecular weight distribution curve was 2 Peaks, and the peak on the low molecular weight side is 250
In the vicinity of 00, a peak on the high molecular weight side exists near 450,000, and the viscosity of the 5% by weight toluene solution at 25 ° C. is 46 c
ps polybutadiene (trade name BR manufactured by Zeon Corporation)
X5000) was dissolved at 8 parts by weight, and n-
Add 0.02 parts by weight of dodecyl mercaptan, 220r
While stirring at pm, block polymerization was carried out at 120 ° C. for 3 hours to make the polymerization rate of styrene 20%. Based on 100 parts by weight of this polymerization solution, 100 parts by weight of water, 1.2 parts by weight of tribasic calcium phosphate, 45 parts by weight of sodium dodecylbenzenesulfonate, 0.75 parts of benzoyl peroxide
Parts by weight, t-butyl peroxybenzoate 0.075
3 parts at 90 ° C, 1 hour at 140 ° C,
The suspension polymerization was carried out while stirring at 220 rpm. Hydrochloric acid was added to the obtained suspension polymerization solution, which was separated by filtration, washed with water, dried, and pelletized by an extruder to obtain a rubber-modified styrene resin composition. Table 1 shows the measurement results and the evaluation results.

Example 2 The same operation as in Example 1 was performed except that the amount of benzoyl peroxide added during suspension polymerization was changed to 0.65 parts by weight. Table 1 shows the measurement results and the evaluation results.

Comparative Example 1 3.3 parts by weight of mineral oil was added to 100 parts by weight of styrene in an autoclave with a stirrer of a complete mixing type having an internal volume of 20 liters, the cis-1,4 bond amount was 93%, and the molecular weight distribution curve was 2 Peaks, and the peak on the low molecular weight side is 250
In the vicinity of 00, a peak on the high molecular weight side exists near 450,000, and the viscosity of the 5% by weight toluene solution at 25 ° C. is 46 c
ps polybutadiene (trade name BR manufactured by Zeon Corporation)
X5000) was dissolved at 8.5 parts by weight, and at the start of the bulk polymerization, 0.02 parts by weight of n-dodecylmercaptan was added.
Bulk polymerization at 120 ° C. for 3 hours while stirring at 0 rpm,
The polymerization rate of styrene was set to 20%. 100 parts of this polymerization solution
In terms of parts by weight, 100 parts by weight of water, 1.2 parts by weight of tribasic calcium phosphate, 45 parts by weight of sodium dodecylbenzenesulfonate and 0.4 parts by weight of benzoyl peroxide were added to the polymerization solution.
85 parts by weight, t-butyl peroxybenzoate 0.0
After adding 75 parts by weight, suspension polymerization was carried out at 90 ° C. for 3 hours and at 140 ° C. for 1 hour while stirring at 220 rpm. Hydrochloric acid was added to the obtained suspension polymerization solution, which was separated by filtration, washed with water, dried, and pelletized by an extruder to obtain a rubber-modified styrene resin composition. Table 1 shows the measurement results and the evaluation results.

Comparative Example 2 The amount of the rubber-like elastic material used was adjusted to 8.0 parts by weight, and the amount of benzoyl peroxide added during suspension polymerization was adjusted to 0.45.
The same operation as in Comparative Example 1 was performed except that the amount was changed to parts by weight. Table 1 shows the measurement results and the evaluation results.

COMPARATIVE EXAMPLE 3 An autoclave with a stirrer of a complete mixing type having an internal volume of 20 liters and having a cis-1,4 bond content of 98%, a molecular weight distribution curve showing a bimodal curve in 100 parts by weight of styrene, and a low molecular weight side Dissolve 8.5 parts by weight of a polybutadiene (Ube Industries, trade name: 22H) having a peak near 150,000 and a high molecular weight peak near 800,000 and having a viscosity of 5% toluene solution at 25 ° C. of 143 cps. At the start of the bulk polymerization, 0.02 parts by weight of n-dodecyl mercaptan was added, and the mixture was stirred at 120 ° C for 2 hours while stirring at 370 rpm.
The bulk polymerization was performed for 0 minutes, and the polymerization rate of styrene was set to 30%. Based on 100 parts by weight of this polymerization liquid, 100 parts by weight of water, 1.2 parts by weight of tribasic calcium phosphate, 45 parts by weight of sodium dodecylbenzenesulfonate, 0.55 parts by weight of benzoyl peroxide, t-butyl peroxy After adding 0.075 parts by weight of benzoate, suspension polymerization was carried out at 90 ° C. for 3 hours and at 140 ° C. for 1 hour while stirring at 220 rpm. Hydrochloric acid was added to the obtained suspension polymerization solution, and the resultant was separated by filtration.
The rubber-modified styrene resin composition was obtained by washing with water, drying and pelletizing with an extruder. Table 1 shows the measurement results and the evaluation results.

Comparative Example 4 2.2 parts by weight of mineral oil were added to 100 parts by weight of styrene in an autoclave equipped with a stirrer of a complete mixing type having an internal volume of 20 liters. 8.0 parts by weight of low cis polybutadiene (trade name: diene 55, manufactured by Asahi Kasei Corporation) having a monomodality and a 5% by weight toluene solution viscosity of 109 cps at 25 ° C. is dissolved, and n-dodecyl mercaptan 0 is added at the start of bulk polymerization. .0
Add 2 parts by weight, and stir at 220 rpm at 120 ° C.
Block polymerization for 2 hours and 30 minutes with styrene polymerization rate of 30%
And Based on 100 parts by weight of this polymerization liquid, 100 parts by weight of water, 1.2 parts by weight of tribasic calcium phosphate, 45 parts by weight of sodium dodecylbenzenesulfonate, 0.60 parts by weight of benzoyl peroxide, t-butyl peroxy Add 0.075 parts by weight of benzoate and add
3 hours and 30 minutes at 140 ° C, 1 hour and 30 minutes at 140 ° C, 220r
The suspension polymerization was carried out while stirring at pm. Hydrochloric acid was added to the obtained suspension polymerization solution, which was separated by filtration, washed with water, dried, and pelletized by an extruder to obtain a rubber-modified styrene resin composition. Table 1 shows the measurement results and the evaluation results. From these results, the following can be understood. An embodiment according to the invention is:
All the evaluation items show satisfactory results. On the other hand, in Comparative Example 1 in which the weight average molecular weight is too small, the Izod impact strength is poor. Comparative Example 2 with excessive weight average molecular weight
Inferior in fluidity. Although the molecular weight distribution curve shows bimodality,
The peak molecular weight is outside the range of the present invention,
Comparative Example 3 using a high cis polybutadiene rubber having a weight% toluene solution viscosity of 143 cps is inferior in Izod impact strength and rigidity. Comparative Example 4 using low cis polybutadiene rubber is inferior in fluidity and rigidity.

[0023]

[Table 1]

[0024]

As described above, according to the present invention,
An inexpensive rubber-modified styrenic resin composition having sufficient rigidity and impact resistance, excellent fluidity and heat resistance, and a molded article using the resin composition can be provided.

Claims (3)

[Claims] 1. A rubber-modified styrenic resin composition in which soft component particles containing a rubbery polymer are dispersed in a styrenic resin forming a continuous phase, and the styrenic resin has a weight average molecular weight of 106,000 to 160,000. In synthesizing such a rubber-modified styrenic resin composition, the rubbery polymer used includes the following (a), (b) and (c)
A rubber-modified styrenic resin composition having the following characteristics: (A) The molecular weight distribution curve shows a bimodal distribution, with a low molecular weight peak between 10,000 and 60,000 and a high molecular weight peak between 300,000 and 600,000. (B) 5% by weight toluene solution viscosity measured at 25 ° C. is 3
It is 0 to 90 cps. (C) High cis polybutadiene having a cis 1,4 bond amount of 70% or more and less than 100%. 2. The rubber-modified styrene resin composition according to claim 1, wherein the content of the rubbery polymer is 6 to 12 parts by weight based on 100 parts by weight of the styrene resin forming the continuous phase. 3. A molded article using the rubber-modified styrenic resin composition according to claim 1 or 2.