JPH04117447A - Styrene resin composition - Google Patents

Abstract

PURPOSE:To improve the balance among heat resistance, impart strength, and mold releasability by compounding a specific rubber-modified styrene resin with a specific mold release agent. CONSTITUTION:The title compsn. comprises a rubber-modified styrene resin which is obtd. by the copolymn. of styrene with a rubberlike polymer and consists of a matrix polystyrene resin having a mol.wt. of 16X10<4>-24X10<4> and contg. 4.0-8.0wt.% particulate rubberlike polymer having a particle size of 1.0-4.0mum, 0.5wt.% or lower in total styrene dimer and trimer and 500ppm or lower residual volatile components, and 500-3000ppm (based on the compsn.) mold release agent consisting of at least one compd. selected from the group consisting of a satd. higher fatty acid and a metal salt thereof and contg. 50wt.% or lower compd. having an m.p. of 100 deg.C or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a rubber-modified styrenic resin composition that has excellent heat resistance, impact resistance, and mold release properties and is suitably used in the fields of home appliances and OA.

[Prior Art] In order to improve the heat resistance of styrenic resins, a method of copolymerizing styrene with a comonomer such as α-methylstyrene, maleic anhydride, or methacrylic acid is generally used. However, the obtained copolymers are expensive due to the high cost of comonomers, and they also have problems such as low fluidity and high hygroscopicity, which limits their uses.

A rubber-modified styrenic resin composition containing a rubbery polymer as dispersed particles in an aromatic monovinyl polymer and having heat resistance, impact resistance, and mold release properties is disclosed in JP-A-1-247446.
However, there is a problem that the aromatic monovinyl polymer has a small molecular weight and does not have sufficient heat resistance.

[Problems to be Solved by the Invention] An object of the present invention is to provide a rubber-modified styrenic resin composition that solves the above-mentioned problems and has an excellent balance of heat resistance, impact resistance, and mold release properties. It is something.

[Means for Solving the Problems] As a result of extensive research in order to solve the above-mentioned problems, the present inventors have found that a specific rubber-like polymer is contained in a matrix polystyrene resin having a specific molecular weight, and styrene The above object is achieved by a styrenic resin composition comprising a rubber-modified styrenic resin in which the total amount of dimer and styrene trimer and the total amount of residual volatile components are less than a specific amount and a specific amount of a specific mold release agent. Based on this knowledge, the present invention was completed.

That is, in the present invention, the molecular weight is 16 x 104 to 24 x 1
Particle size 1.0 in matrix polystyrene resin of 04
~4.0μm particulate rubbery polymer from 4.0 to 8.0μm
Weight%, total amount of styrene dimer and styrene trimer is 0.
5% by weight or less, total residual volatile components 500 pprn
1 selected from saturated higher aliphatic carboxylic acids and metal salts thereof in an amount of 500 to 3000 ppm based on the rubber-modified styrenic resin (A) obtained by polymerizing the styrene and rubber-like polymerized monomer containing the following: The present invention provides a styrenic resin composition characterized by comprising a mold release agent (B) comprising a species or two or more kinds of compounds, and a compound having a melting point of 100'C or less accounts for 50% by weight or less.

The rubber-modified styrenic resin (A) in the present invention is obtained by polymerizing styrene and a rubbery polymer, and can be obtained by a method commonly used in the production of conventional rubber-modified styrenic resins, such as emulsion polymerization, bulk polymerization, etc. Although it can be produced by any method such as polymerization method, bulk-suspension polymerization method, or suspension polymerization method, in the present invention, from an economically advantageous point, bulk-suspension polymerization method or continuous polymerization method is used. A manufacturing method based on bulk polymerization is selected.

Next, an example of the method for producing the rubber-modified styrenic resin of the present invention will be described. First, a rubber-like polymer is added to a mixed solution containing styrene and other copolymerizable monomers used as desired, and dissolved at a temperature of about 20 to 700 C. Polymerization is carried out by supplying the polymer to a polymerization vessel having more than one stage, preferably two or more stages, and from the final stage of the polymerization, the desired amount is removed through a devolatilizing component step in which solid components and volatile components such as unreacted monomers and solvents are separated. of resin is obtained.

In this method, a rubber-like polymer dissolved in a monomer is supplied to the first stage polymerization vessel, and the monomer and a polymerization initiator and chain transfer agent used as desired are It may be supplied to the polymerization vessel at any stage.

In this polymerization method, examples of the polymerization initiator used as desired include t-butyl hydroperoxide,
di-t-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide,
1,1-bis(t-butylperoxy)cyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)
3.3.5-Trimethylcyclohexane, 2,2-bis(4,4-di-t-butylperoxycyclohexane)
Organic peroxides such as propanone, azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile,
Examples include azo compounds such as azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, and azobiscyanovaleric acid. These can be used alone or in combination of two or more, but it is preferable to use a mixture of those with a half-life temperature (10 hours) of 100° C. or lower and one with a half-life temperature of 100° C. or higher.

Chain transfer agents that can be used as desired include, for example, mercaptans such as n-dodecylmercaptan and t-dodecylmercaptan, α-methylstyrene dimer, 1-phenyl-butene-2-fluorene, tilpinol, and chloroform. can be mentioned.

The styrenic resin as a matrix component obtained by polymerizing styrene monomers is a styrene homopolymer or a copolymer of a monomer copolymerizable with styrene, and the copolymerizable monomers include: For example, α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, p-
Aromatic monovinyl compounds such as t-butylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene, acrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, maleic anhydride, phenylmaleimide, etc. I can do it. These monomers may be used alone or in combination of two or more types, but they usually account for 50% by weight or less, preferably 40% by weight or less, based on the total monomers containing styrene. Used in percentages.

There are no particular restrictions on the type of rubber-like polymer, and those conventionally used in rubber-modified styrenic resins, such as natural rubber, polybutadiene rubber, polyisoprene rubber,
Synthetic rubbers such as styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, butyl rubber, ethylene-propylene copolymer rubber, or graft copolymer rubbers of these rubbers and styrene are used.

The amount of the rubbery polymer in the rubber-modified styrenic resin obtained as described above is determined by calculation from the charged rubber concentration and the final conversion rate of the resin. Further, the particle size of the rubbery polymer is determined as the area average particle size (diameter) (DS) of the rubbery polymer as follows. Specifically, pellets of a rubber-modified styrenic resin with a small degree of orientation were treated with a 3% by weight osmium tetroxide aqueous solution, and then sliced into thin sections using an ultramicrotome. A transmission electron microscope image of this pellet was obtained, and the rubber-like appearance in the image was obtained. The diameter of the polymer particles in the major axis direction (D
) is measured for about 1000 particles, and the area average value is determined according to the following formula to obtain the area average particle size (diameter) (Ds) of the rubbery polymer.

(n is the number of rubbery polymer particles in diameter.) The content of the rubbery polymer is 4. It is necessary that the content is 0 to 8.0% by weight; if it is less than 4.0% by weight, the impact resistance will decrease, and if it exceeds 8.0% by weight, the heat resistance will decrease. The preferred range is 4.
It is 0 to 7.5% by weight. Also, the particle size of the rubbery polymer is 1
．． It is necessary that the thickness is 0 to 4°0 μm; if it is less than 1.0 μm, the impact resistance will decrease. If it exceeds 0 μm, impact resistance and heat resistance will decrease. The preferred range is 1.2-3
．． It is 6 μm.

Next, the molecular weight of the matrix polystyrene resin is determined as follows. That is, after dissolving the rubber-modified styrene resin in methyl ethyl ketone, it was centrifuged to remove the gel component, and the supernatant containing the matrix component was dried. Thereafter, 0.0% of the matrix component was prepared using tetrahydrofuran as a solvent. A 2% by weight solution was prepared, and the weight average molecular weight (Mw) was determined in terms of polystyrene using GPC150C manufactured by Waters. The molecular weight of the matrix polystyrene resin is 16X104~24
It is necessary to be in the range of ×104, and if it is less than 16×104, impact resistance and heat resistance will decrease, and if it exceeds 24×104, fluidity will decrease.

The preferred range is 17x104 to 23x104.

Furthermore, the rubber-modified styrenic resin of the present invention requires that the total amount of styrene dimers and trimers in the resin be 0.5% by weight or less. If the total amount exceeds 0.5% by weight, heat resistance will decrease. The preferred range is 0. It is 4% by weight or less. Furthermore, the rubber-modified styrenic resin of the present invention is
It is necessary that the total amount of residual volatile components in the resin is 500 ppm or less. If this total amount exceeds 500 ppm, heat resistance will decrease. Preferred range is 400 ppm
It is as follows. The remaining volatile components include styrene, isopropylbenzene, n-propylbenzene, ethylbenzene, and the solvent used in the polymerization.

The total amount of the above styrene dimer and trimer and the total amount of residual volatile components were measured using a gas chromatography GC-3 manufactured by Shimadzu Corporation.
It was determined using BF.

Next, as the saturated higher aliphatic carboxylic acid used as component (B), a linear saturated monocarboxylic acid having about 12 to 42 carbon atoms is used. For example, lauric acid (44℃
), myristic acid (54℃), palmitic acid (636C
), stearic acid (70°C), behenic acid (81°C), and montanic acid (89°C). The metals of these metal salts include lithium, sodium, potassium, magnesium, calcium, aluminum, zinc, etc. Typical metal salts of higher aliphatic carboxylic acids include:
Magnesium stearate (132℃), aluminum stearate (103℃), calcium stearate (
(180°C), zinc stearate (140°C), etc. (The melting point is shown in parentheses).

In the composition of the present invention, the mold release agent (B) is composed of one or more compounds selected from the above-mentioned saturated higher fatty acids and metal salts thereof, and the compound having a melting point of 100°C or less is
It is necessary that the amount is below % by weight. If the content of the compound having a melting point of 100° C. or lower exceeds 50% by weight, heat resistance will decrease. In addition, the amount of the mold release agent is 500 to 3000pp relative to the composition.
It is necessary that m. If it is less than 500 ppm, mold releasability will decrease, and if it exceeds 3000 ppm, heat resistance will decrease. The preferred range is 1000 to 2500 ppm.

There are no particular restrictions on the method of adding the mold release agent, and it can be added to a styrene solution in which rubber, which is a raw material for rubber-modified styrenic resin, is dissolved, or added to the polymerization process or devolatilization process, or it can be added to the styrene solution. It may be added to the resin pellet.

The rubber-modified styrenic resin composition of the present invention may contain various commonly used additives, such as lubricants such as ethylene bisstearamide, organic polysiloxane,
Mineral oil, etc., and antioxidants such as hindered phenols, hindered bisphenols, etc.
Hindered trisphenols, etc. Also, for example, 2.
6-di-t-butyl-4-methylphenol, stearyl-β-(3,5-di-t-butyl-4-human-7xyphenyl)propionate, triethylene glycol-bis-3-(3-t-butyl- 4-hydroxy-6-methylphenyl) propionate, etc., or phosphorus compounds such as tri(2°4-di-t-butylphenyl)phosphite, 4,4'-butylidene-bis-(3-methyl-6 -t-butylphenyl-di-tridecyl) phosphite, etc. can be added. Furthermore, stabilizers, dyes, pigments, fillers, lubricants, plasticizers, antistatic agents, etc. can be added as necessary.

Furthermore, the styrenic resin composition of the present invention may optionally contain
General purpose polystyrene (GPPS) and other polymers such as polyphenylene ether, ABS, etc. can also be blended.

[Examples] The present invention will be described below based on Examples, but the present invention is not limited thereto. In addition, the measurement method of physical properties etc. is shown below.

(1) Melt index (M I ) J Is-
Measured in accordance with 7210.

(2) Izot impact strength Measured according to J Is-7110 (23°C, with notch).

(3) Place the ball pressure temperature test piece in a constant temperature bath, apply a static load of 2ON for 1 hour using a steel ball with a diameter of 5mm, then remove the ball pressure test piece and immediately place it in water at 259C ± 5C. After cooling for 30 minutes, the diameter of the hollow hole was measured to be 2 mm.
(If converted by depth, the temperature is 0.209mm).

(4) Mold releasability Complex molded products with many ribs and bosses were injection molded at a molding temperature of 220° C., and the appearance of the molded products was evaluated using the following rankings.

◎: No scratches or whitening at all.

O: There are slight scratches and whitening.

△: There are considerable scratches and whitening.

×: There are scratches, whitening, and cracks.

Example 1 A mixture of the following composition at a feed rate of 201/hr was fed into a volume of 23
The solution was continuously fed to the first polymerization tank of ρ.

Rubber-like polymer: NF35AS (polybutadiene manufactured by Asahi Kasei Industries) 5.2% by weight styrene 89.8% by weight ethylbenzene
5.0% by weight n-dodecylmercaptan 200 ppm 1.1-bis(t-butylperoxy)3,3°5-trimethylcyclohexane
300ppm2.5-dimethyl-2,5-di(t-butylperoxy)hexane 1100pp
The temperature of the first polymerization tank is 115℃, and the rotation speed is 150r.
It was pm.

Next, the liquid was sequentially sent to a second polymerization tank with a capacity of 331 and a third polymerization tank with a capacity of 331. Temperature and rotation speed are 137℃ and 5, respectively.
The temperature was 0 rpm, 160° C., and 2 Orpm.

Further, the addition rate at the outlet of the third polymerization tank was 85% by weight.

Furthermore, volatile components were removed in a vacuum chamber heated to a temperature of 230 to 280°C to obtain a pellet-shaped rubber-modified styrene resin. The following operating conditions are shown in Table 1.

This pellet contains 2500pp of calcium stearate.
m was added and kneaded using an extruder. Table 2 shows the composition and physical properties of the resulting resin composition and the resin structure of the rubber-modified styrene resin.

Examples 2 to 4 In Example 1, the operating conditions were changed as shown in Table 1, and the release agent composition was changed as shown in Table 2.

Table 2 shows the physical properties of the obtained resin composition and the resin structure of the rubber-modified styrene resin.

Comparative Examples 1 to 5 In Example 1, the operating conditions were changed as shown in Table 1, and the release agent composition was changed as shown in Table 2.

Table 2 shows the physical properties of the obtained resin composition and the resin structure of the rubber-modified styrene resin.

[Effects of the Invention] According to the present invention, it is possible to obtain a styrenic resin composition that has an excellent balance of heat resistance, impact resistance, and mold releasability, and has particularly excellent heat resistance.

Therefore, the styrenic resin composition of the present invention can be used in home appliances, O
It is suitably used as a material in the A field, and its industrial value is extremely large.

Claims (1)

[Claims] 1. Particle size of 1.0 to 4.0 μm in matrix polystyrene resin with molecular weight of 16 x 10^4 to 24 x 10^4
Styrene containing 4.0 to 8.0% by weight of a particulate rubbery polymer, 0.5% by weight or less of styrene dimer and styrene trimer in total, and 500ppm or less of residual volatile components in total. 500 to 3000 p to the rubber-modified styrenic resin (A) and composition obtained by polymerizing a rubbery polymer
A mold release agent consisting of one or more compounds selected from pm saturated higher aliphatic carboxylic acids and their metal salts, and containing 50% by weight or less of compounds with a melting point of 100°C or less (
A styrenic resin composition comprising B).