JPH1087955A - Resin composition having low odor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition having low odor, capable of satisfactorily retaining operation environment in molding and processing by copolymerizing an aromatic vinyl-based monomer with a vinyl cyanide-based monomer in the presence or absence of a rubberlike polymer so that the resultant copolymer has a prescribed total volatile content and a prescribed total sulfur content. SOLUTION: This resin composition is obtained by copolymerizing a monomer mixture consisting essentially of (B) preferably 65-85wt.% aromatic vinyl-based monomer such as styrene and (C) preferably 15-35wt.% vinyl cyanide-based monomer such as acrylonitrile in the presence or absence of (A) preferably 0-40wt.% rubber like polymer such as polybutadiene, and has <=0.5wt.% total volatile content and <=1,000ppm total sulfur content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a styrene resin composition having excellent low odor.

[0002]

2. Description of the Related Art An AS resin as a copolymer obtained by polymerizing a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components, rubber-reinforced AB
S resins and the like are widely used because they have excellent moldability and chemical resistance and have relatively good appearance.

However, in recent years, environmental issues at factories have been taken up, and the environment during resin molding has been gaining attention. Especially AS resin and ABS
In the molding of resins, styrene remaining in the resin in many cases without polymerization, aromatic vinyl monomers such as α-methylstyrene, vinyl cyanide monomers such as acrylonitrile, N-phenyl There has been a problem that an imide-based monomer such as maleimide is volatilized by heating the resin at the time of molding to deteriorate the working environment. These resins also have a unique odor. Until now, no particular countermeasures have been taken with respect to such problems as deterioration of the working environment and odor due to various residual monomers during molding.

[0004]

The inventors of the present invention have conducted intensive studies for the purpose of improving the working environment, and as a result, the above-mentioned problems have been solved by reducing both the total volatile content and the sulfur content in the resin. And found the present invention.

[0005]

According to the present invention, a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components in the presence or absence of a rubbery polymer is provided. A low-odor copolymer which is obtained by polymerization, wherein the total volatile content of the copolymer is 0.5% by weight or less and the total sulfur content in the copolymer is 1000 ppm or less. Resin composition.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention is achieved by reducing both the total volatile content and the sulfur content in a resin.
The object of the invention is not achieved only by reducing each alone. The details will be described below. The resin composition of the present invention is a copolymer obtained by polymerizing a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components.

The aromatic vinyl monomer used for polymerization in the present invention includes, for example, vinyltoluenes such as styrene, α-methylstyrene, p-methylstyrene, and p-toluene.
-Halogenated styrenes such as chlorostyrene, pt-
Butylstyrene, dimethylstyrene, vinylnaphthalenes and the like can be used, and styrene or α-methylstyrene is preferable. These aromatic vinyl monomers can be used alone or in combination of two or more.

[0008] The amount of the aromatic vinyl monomer used is 60 to 90% by weight, preferably 65 to 85% by weight in the monomer mixture. If the amount is less than 60% by weight, the moldability of the obtained resin composition is deteriorated, and if it exceeds 90% by weight, the toughness of the resin is reduced.

As the vinyl cyanide monomer used for the polymerization, acrylonitrile, methacrylonitrile, vinylidene cyanide and the like can be used, and acrylonitrile is preferred.

The amount of the vinyl cyanide monomer used is 10 to 40% by weight, preferably 15 to 35% by weight in the monomer mixture. If it is less than 10% by weight, the toughness of the obtained resin composition will be reduced, and if it exceeds 40% by weight, the moldability will be deteriorated.

In addition to these aromatic vinyl monomers and vinyl cyanide monomers, other monomers copolymerizable therewith can be copolymerized. These monomers include unsaturated carboxylic ester monomers, unsaturated dicarboxylic anhydrides and unsaturated dicarboxylic imide compounds, and these may be used alone or in combination of two or more. Can be.

Examples of the copolymerizable unsaturated carboxylic acid ester-based monomers include, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-acrylic acid.
Examples include ethylhexyl, n-hexyl acrylate, methyl methacrylate, and ethyl methacrylate. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

As the copolymerizable unsaturated dicarboxylic anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride and the like can be used, and maleic anhydride is preferred.

Examples of the copolymerizable unsaturated carboxylic acid imide compound include maleimide, N-methylmaleimide, and N-methylmaleimide.
-Butylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide and the like can be used.
Phenylmaleimide.

The use amount of these other copolymerizable monomers is in the range of 0 to 20% by weight in the monomer mixture, and when the use amount exceeds 20% by weight, the toughness of the obtained resin is reduced. It decreases significantly.

In the present invention, if necessary, other monomers such as glycidyl methacrylate, methacrylic acid, acrylic acid, methacrylamide, 2-hydroxyethyl methacrylate, and polyethylene glycol monomethacrylate may be added in an amount of 20% by weight or less. Preferably, an amount of 15% by weight or less can be used in the monomer mixture.

Further, when polymerizing these monomers, graft polymerization may be performed in the presence of a rubbery polymer. Examples of the rubbery polymer include polybutadiene, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), diene rubbers such as isoprene rubber and chloroprene rubber, and acrylic rubbers such as poly (n-butyl acrylate) rubber. , Ethylene-propylene-diene rubber (EP rubber) and the like can be optionally used.

These rubbery polymers are contained in the resin composition in an amount of 0%.
５０50% by weight, preferably 0-40% by weight. If the content exceeds 50% by weight, the rigidity and moldability of the resin are undesirably reduced. The thus obtained graft copolymer may be used alone, or the graft copolymer and the copolymer containing no rubber component may be blended.

The total volatile content in the resin composition is limited to 0.5% by weight or less in order to achieve the object of the present invention. It is preferably at most 0.3% by weight. If the content exceeds 0.5% by weight, it is not possible to improve the working environment and solve the problem of odor, which are the objects of the present invention. The main components of this volatile component are aromatic vinyl monomers and vinyl cyanide monomers remaining without polymerization, and copolymerizable monomers used as the main components. In addition, a polymerization initiator, a chain transfer agent, an emulsifier, and their altered or decomposed products used in the polymerization are often found. In particular, it is preferable to reduce harmful aromatic vinyl monomers and vinyl cyanide monomers for the purpose of improving the working environment during molding.

Any method may be used to reduce the total volatile content. For example, a method of increasing the polymerization rate to reduce the amount of residual monomers, a method of removing volatile components under a strong vacuum when kneading with an extruder, a relatively large molecular weight in an initiator or an emulsifier, and decomposition It is possible to adopt a method of using a material that is difficult to perform, and it is optional to perform these methods alone or in combination.

The sulfur content in the resin composition as well as the total volatile content is limited to 1000 ppm or less, preferably 500 ppm or less. The sulfur content is not always contained in the volatile matter. Therefore, even if the total volatile content is set to 0.5% by weight or less, the object of the present invention is not achieved if the sulfur content exceeds 1000 ppm. That is, the gist of the present invention is to reduce odor by simultaneously reducing both the total volatile content and the sulfur content in the resin composition.

The breakdown of the sulfur content in the resin includes a mercaptan compound as a chain transfer agent used to control the degree of polymerization, a dialkyl disulfide obtained by chemically changing these compounds, and a sulfuric acid used as a thickener or a coagulant for latex. The main ones are salts, persulfates used as polymerization initiators, sulfonic acid groups bonded to polymer chain terminals, and the like. Of course, if no mercaptan compound is used as the chain transfer agent, no mercaptan compound or disulfide is contained.

As a method for reducing the sulfur content in the resin, any means can be adopted. For example, a method for reducing the amount of a mercaptan compound used as a chain transfer agent or a persulfate used for a polymerization initiator, a method for removing a sulfur compound remaining in a polymer by a reprecipitation method after polymerization, and kneading with an extruder At this time, a method of removing a sulfur compound under a strong vacuum, a method of using a salt other than sulfuric acid for coagulating latex, or the like can be used alone or in combination.

[0024]

The present invention will be described below more specifically with reference to examples and comparative examples. In addition, "%" and "part" in the following examples are based on weight unless otherwise specified. In the description, various physical properties were measured by the following methods.

(1) Total volatiles After drying the copolymer in vacuum at 60 ° C. for 24 hours,
The volatile matter generated by heating to ° C. was measured by gas chromatography, and was obtained in terms of% by weight.

(2) Sulfur content Sulfur content was determined by the atomic absorption method.

(3) Judgment of odor: 100 g of the pellets were kneaded with a roll at a processing temperature of 200 ° C. for 3 minutes.

Example 1 70 parts of styrene, 30 parts of acrylonitrile, 25 parts of methyl ethyl ketone, 25 parts of 1,1'-azobis (cyclohexane-1-carbonitrile), 0.4 part of styrene 70 parts While continuously supplying 0.3 parts of terpinolene, and keeping the temperature inside the polymerization reactor constant at 110 ° C., the polymerization reaction solution was supplied by a gear pump provided at the bottom of the polymerization reactor so that the average residence time was 2 hours. The polymerization reaction solution was continuously withdrawn and allowed to stay in a heat exchanger maintained at 140 ° C. for about 20 minutes. Thereafter, the mixture was introduced into a 2-vent type twin-screw extruder having a cylinder temperature of 200 ° C., the first vent was at atmospheric pressure, and the second vent was at 20 to.
The volatile components were devolatilized under a reduced pressure of rr, and the strand discharged from the extruder was pelletized by a pelletizer to obtain a copolymer (A). Table 1 shows the measurement results and the odor determination results of the total volatiles and sulfur content of the obtained copolymer (A).

Example 2 In a 10 liter stainless steel autoclave, 140 parts of ion-exchanged water, 90 parts of 1,3-butadiene, 10 parts of styrene, 2.5 parts of potassium rosinate, 0.2 parts of sodium dodecylbenzenesulfonate, 0.2 parts of sodium hydroxide. 1 part Dextrose 0.2 part Diisopropylbenzene hydroperoxide 0.2 part Sodium pyrophosphate 0.1 part Ferrous sulfate heptahydrate 0.003 part was charged and heated to 50 ° C. The internal temperature was controlled to be constant at 50 ° C., and after 7 hours, residual 1,3-butadiene was removed by steam distillation, followed by cooling to obtain a rubber latex.

To the obtained rubber latex, 0.5 part of a 1% aqueous sulfuric acid solution (as an amount of sulfuric acid) was added dropwise over 10 minutes while stirring, and stirring was continued for 3 minutes after completion of the addition. Then 10%
Aqueous potassium hydroxide solution (as potassium hydroxide component)
By adding 7 parts, a rubber latex having a weight average particle size of 280 nm was obtained. 50 parts of the obtained rubber latex ion-exchanged water (including those in rubber latex) 150 parts Dextrose 0.3 part Sodium pyrophosphate 0.1 part Ferrous sulfate heptahydrate 0.005 part The glass reactor was charged and heated to 60 ° C. Thereafter, a mixture composed of 15 parts of acrylonitrile, 35 parts of styrene, 0.25 parts of cumene hydroperoxide, and 0.5 parts of terpinolene was dropped over 200 minutes to carry out polymerization. After dropping, cumene hydroperoxide 0.10
Then, the mixture was aged for 1 hour and cooled. The obtained latex was put into an aqueous sulfuric acid solution and solidified to obtain a white powdery graft copolymer (B).

The copolymer (A) of Example 1 (60 parts by weight) and the graft copolymer (B) were mixed at a cylinder temperature of 220 ° C.
The vent was devolatilized and kneaded under reduced pressure of 20 torr using a twin-screw extruder to obtain a pellet-shaped ABS resin composition.
Table 1 shows the measurement results and the odor judgment results of the total volatiles and sulfur content of the obtained copolymer.

Comparative Example 1 In Example 1, the amount of 1,1'-azobis (cyclohexane-1-carbonitrile) used was changed to 0.1 part, and the second vent of the extruder was opened to the atmosphere. The polymerization was carried out in the same manner as in Example 1 to obtain a pellet-shaped copolymer (C). Table 1 shows the measurement results and the odor judgment results of the total volatiles and sulfur content of the obtained copolymer.

Comparative Example 2 The procedure of Example 1 was repeated, except that the chain transfer agent terpinolene was changed to t-dodecyl mercaptan. A combination (D) was obtained. Table 1 shows the results of measuring the total volatile components and sulfur in the obtained copolymer and the results of determining the odor.

Comparative Example 3 60 parts by weight of the copolymer (A) obtained in Example 1 and the graft copolymer (B) obtained in Example 2 were mixed with a twin-screw extruder having a cylinder temperature of 220 ° C. The vent was kneaded in the open to the atmosphere to obtain a pellet-shaped ABS resin composition. Table 1 shows the measurement results and the odor judgment results of the total volatiles and sulfur content of the obtained copolymer.

Comparative Example 4 60 parts by weight of the copolymer (D) obtained in Comparative Example 2 and the graft copolymer (B) obtained in Example 2 were mixed with a twin-screw extruder having a cylinder temperature of 220 ° C. The vent was devolatilized and kneaded under a reduced pressure of 20 torr to obtain a pellet-shaped ABS resin composition. Table 1 shows the measurement results and the odor judgment results of the total volatiles and sulfur content of the obtained copolymer.

[0036]

[Table 1]

[0037]

The resin composition of the present invention has a low odor due to monomers and sulfur components contained in the resin at the time of processing, so that a good working environment can be maintained and sanitary.

Claims (1)

[Claims] 1. A copolymer obtained by polymerizing a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components in the presence or absence of a rubbery polymer. A low odor resin composition characterized in that the total volatile content of the copolymer is 0.5% by weight or less and the total sulfur content in the copolymer is 1000 ppm or less.