JP2002114822A - Copolymer resin composition and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copolymer resin composition minimized in coloring, less prone to generate brown or black colored foreign matters in manufacturing and molding. SOLUTION: This copolymer composition is obtained by copolymerizing a styrenic based monomer and one or more kinds of monomers selected from a (meth)acrylate based monomer, (meth)acrylic acid, (meth)acrylonitrile in the presence of 4,6-bis(octylthiomethyl)-o-cresol, including <=1,000 ppm of the remaining comonomers and the invention includes a method of manufacturing the resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer resin composition which is less colored at the time of production and molding, and is less likely to produce a yellow-brown or black foreign matter.

[0002]

2. Description of the Related Art Hitherto, styrene copolymer resins such as MS resin and AS resin have been used in various fields such as light electric appliances and miscellaneous goods because of their good moldability and excellent transparency and chemical resistance. Was. However, it has been pointed out that these copolymer resins are more likely to be colored at the time of production or molding than GPPS, and that a foreign substance which changes color from yellow-brown to black, which is called burn, is generated during long-term use. On the other hand, volatile components mainly composed of monomers remaining in the styrenic copolymer resin are required to be reduced because they may cause odor at the time of molding or cause coloring at the time of molding. I have. However, in order to reduce volatile components, it is necessary to devolatilize at a high temperature or use an extruder having a high kneading property, so that there are problems such as coloring of the copolymer resin and occurrence of burns. .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a copolymer resin composition which is less colored at the time of production and molding, and which hardly generates yellowish brown or black discolored foreign matter.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the object, and as a result, have found that a styrene monomer and another monomer are copolymerized in the presence of a specific compound. The present invention was found to be a resin composition obtained by controlling the amount of the remaining monomer in a specific range so as to cause less coloring and less occurrence of burn.

That is, the present invention provides a copolymer obtained by copolymerizing a styrene monomer and at least one monomer selected from the following in the presence of 4,6-bis (octylthiomethyl) -o-cresol: The present invention relates to a copolymer resin composition, wherein the total amount of the remaining monomers is less than 1000 ppm, and a method for producing the same. (Meth) acrylic acid ester monomer (Meth) acrylic acid (Meth) acrylonitrile

Hereinafter, the present invention will be described in detail. The styrene monomer used in the present invention includes styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, etc., and is preferably styrene. These styrene monomers may be used alone or in combination of two or more.

The (meth) acrylate monomers used in the present invention include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylhexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, methyl acrylate,
Ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate and the like can be mentioned, and methyl methacrylate and n-butyl acrylate are preferred.

The (meth) acrylic acid used in the present invention is acrylic acid or methacrylic acid. The (meth) acrylonitrile used in the present invention is acrylonitrile and methacrylonitrile.

In the present invention, a styrene monomer and at least one monomer selected from the following are copolymerized in the presence of 4,6-bis (octylthiomethyl) -o-cresol. (Meth) acrylic acid ester monomer (Meth) acrylic acid (Meth) acrylonitrile

The proportion of the monomers to be copolymerized is preferably
Styrene-based monomer: Total of (meth) acrylate-based monomer, (meth) acrylic acid and (meth) acrylonitrile = 1-99% by mass: 99-1% by mass, more preferably 5-95% by mass : 95 to 5% by mass.

A (meth) acrylate monomer,
The (meth) acrylic acid and (meth) acrylonitrile are not particularly limited as long as they are at least one kind.

The 4,6-bis (octylthiomethyl) -o-cresol used in the present invention is commercially available. For example, IRGANO manufactured by Ciba Specialty Chemicals
X1520L. The amount of 4,6-bis (octylthiomethyl) -o-cresol used is preferably from 0.005 to 1 part by mass, more preferably from 0.01 to 1 part by mass, based on 100 parts by mass of the total of the monomers.
0.2 parts by mass. If copolymerization is carried out in the absence of 4,6-bis (octylthiomethyl) -o-cresol, coloring becomes strong and burns are liable to occur.

Also, 4,6-bis (octylthiomethyl) -o-cresol preferably has a monomer conversion of 3
It is present at a stage of 0% by mass or more, more preferably 35% by mass or more. When the conversion of the monomer is present at a stage of less than 30% by mass, the remaining monomer may increase or may be colored.

In the presence of 4,6-bis (octylthiomethyl) -o-cresol, the monomer is preferably 2% by mass.
It is important to copolymerize the above, more preferably 3% by mass or more. 4,6-bis (octylthiomethyl) -o-
If not copolymerized in the presence of cresol, in other words,
Simply blending makes it difficult to suppress the occurrence of burns.

The copolymerization method in the present invention is not particularly limited, and bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization and the like can be employed, and any of a batch polymerization method and a continuous polymerization method can be used. Although it does not matter, a particularly high effect is obtained in the continuous polymerization method of bulk polymerization or solution polymerization exposed to high temperature in a devolatilizing preheater.

At the time of copolymerization, known azo compounds such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile, benzoyl peroxide, t-butylperoxybenzoate, 1,1-bis (t -Butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, dicumyl peroxide, Known organic peroxides such as ethyl-3,3-di- (t-butylperoxy) butyrate can also be used. Also, known molecular weight regulators such as t
-Dodecyl mercaptan, n-dodecyl mercaptan,
Polymerization may be carried out by adding 4-methyl-2,4-diphenylpentene-1 as needed.

The total amount of the monomers remaining in the copolymer resin composition of the present invention is less than 1000 ppm, preferably less than 800 ppm.
It is less than ppm, more preferably less than 600 ppm. If the total amount of the remaining monomers exceeds 1000 ppm, it is not preferable because odor becomes strong during molding and coloring becomes strong.

If necessary, additives such as an antioxidant, a weathering agent, a lubricant, a plasticizer, a coloring agent, an antistatic agent, a mineral oil, a flame retardant and the like may be added to the copolymer resin composition of the present invention. It can be blended at any stage during production.

The copolymer resin composition of the present invention can be obtained by injection molding,
It is processed into various molded articles by a known method such as extrusion molding, compression molding, and vacuum molding, and is put to practical use. If necessary, the copolymer resin composition of the present invention may contain an ABS (styrene-acrylonitrile-butadiene) graft product, MBS
(Methyl methacrylate-styrene butadiene) It is also possible to melt-knead with another resin such as a graft product, polycarbonate, polyamide, polyester or the like, or to mold directly with another resin.

[0020]

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A first reactor which is a complete mixing type stirring tank having a capacity of about 20 L and a second reactor which is a tower type plug flow reactor with a stirrer having a capacity of about 40 L are connected in series. And two devolatilizing tanks were connected in series. Ethyl benzene was added to 85 parts by mass of a monomer solution composed of 42% by mass of styrene and 58% by mass of methyl methacrylate (hereinafter, MMA).
5 parts by mass, 0.01 parts by mass of t-butyl peroxyisopropyl monocarbonate, and 0.3 parts by mass of t-dodecyl mercaptan were mixed to prepare a raw material solution. This raw material solution was supplied to the first reactor controlled at 125 ° C. at 6.0 kg per hour. The conversion at the outlet of the first reactor was 36% by mass. At the entrance of the second reactor, 0.1 part by mass of 4,6-bis (octylthiomethyl) -o-cresol was continuously added to 85 parts by mass of the monomer solution, and 12 parts by mass in the direction of flow.
It was introduced into a second reactor adjusted to have a gradient of 5 ° C to 160 ° C. The conversion at the outlet of the second reactor is 85% by mass.
Met. Next, after heating to 160 ° C with a preheater, 67 kP
into the first devolatilization tank, which was decompressed to a.
After heating to 0 ° C., the mixture was introduced into a second devolatilization tank having a reduced pressure of 1.3 kPa to remove monomers. This was extruded and cut into a strand to obtain a pellet-shaped copolymer resin composition. Table 1 shows the physical property evaluation results.

Example 2 The same configuration as in Example 1 was used. 92% by mass of styrene,
15 parts by mass of ethylbenzene, t with respect to 85 parts by mass of a monomer solution composed of 8% by mass of methacrylic acid (hereinafter, MAA), t
-Butyl peroxyisopropyl monocarbonate 0.
01 parts by mass and 0.3 parts by mass of t-dodecyl mercaptan were mixed to prepare a raw material solution. Other than that, it carried out similarly to Example 1. Table 1 shows the physical property evaluation results.

Example 3 The same configuration as in Example 1 was used. 75% by mass of styrene,
15 parts by mass of ethylbenzene, 0.01 part by mass of t-butylperoxyisopropyl monocarbonate, and 0.3 part by mass of t-dodecyl mercaptan are added to 85 parts by mass of a monomer solution composed of 25 mass% of acrylonitrile (hereinafter, AN).
The parts by mass were mixed to obtain a raw material solution. Other than that, it carried out similarly to Example 1. Table 1 shows the physical property evaluation results.

Example 4 The same operation as in Example 1 was performed except that the second devolatilizing tank was 3.9 kPa. Table 1 shows the physical property evaluation results.

Example 5 A raw material solution was mixed with 0.01 part by mass of 4,6-bis (octylthiomethyl) -o-cresol and introduced into the first reactor, and 4,6-bis (octylthiomethyl) -o-cresol was introduced into the first reactor. Example 3 except that bis (octylthiomethyl) -o-cresol was not added
The same was done. Table 1 shows the physical property evaluation results.

Comparative Example 1 The same operation as in Example 1 was carried out except that 4,6-bis (octylthiomethyl) -o-cresol was not added. Table 1
The results of evaluation of physical properties are shown in FIG.

Comparative Example 2 The same operation as in Example 2 was carried out except that 4,6-bis (octylthiomethyl) -o-cresol was not added. Table 1
The results of evaluation of physical properties are shown in FIG.

Comparative Example 3 The same operation as in Example 3 was carried out except that 4,6-bis (octylthiomethyl) -o-cresol was not added. Table 1
The results of evaluation of physical properties are shown in FIG.

Comparative Example 4 The procedure was the same as in Example 1 except that the second devolatilizing tank was set at 6.5 kPa. Table 1 shows the physical property evaluation results.

Comparative Example 5 0.1 part by mass of 4,6-bis (octylthiomethyl) -o-cresol was added to 100 parts by mass of the resin obtained in Comparative Example 1, and the mixture was melt-kneaded by an extruder. Table 1 shows the physical property evaluation results.

[0031]

[Table 1]

The evaluation was performed according to the following method. (1) Total of Residual Monomer Concentrations Using a gas chromatography GC12A manufactured by Shimadzu Corporation, cyclopentane was measured as an internal standard, and totaled.

(2) Yellowness Using an injection molding machine (IS-50EP) manufactured by Toshiba Machine Co., Ltd., a test piece having a size of 40 mm × 120 mm × 2 mm was measured at a cylinder temperature of 250 ° C. and a mold temperature of 40 ° C. Molded. Using this test piece, a color difference meter SM-5 manufactured by Suga Test Instruments Co., Ltd.
Was used to measure the b value according to JIS K7105. (Unit:-)

(3) Coloring property during heating and retention Using an injection molding machine (IS-50EP) manufactured by Toshiba Machine Co., Ltd., the cylinder temperature was set to 250 ° C., the resin was retained in the cylinder for 30 minutes, and the mold temperature was set to 40. 40mm × 120 at ℃
A test piece having a size of 2 mm × 2 mm was formed. Using this test piece, the color difference meter SM-5 manufactured by Suga Test Instruments Co., Ltd.
The b value was measured according to K7105. (Unit:-)

(4) Burn Using an injection molding machine (IS-50EP) manufactured by Toshiba Machine Co., Ltd., the cylinder temperature was set to 250 ° C., the resin was retained in the cylinder for 3 hours, and the mold temperature was set to 40 ° C. and 40 mm × 120.
A test piece having a size of 2 mm × 2 mm was formed. The test piece was evaluated as X when clear burns occurred, Δ when slight burns occurred, and ○ when no burns occurred.

(5) Odor at the time of molding (2) In the evaluation of yellowness, those which felt strong odor during molding were evaluated as x, and those which did not feel strong odor were evaluated as ○.

The examples relating to the copolymer resin composition of the present invention are superior in the balance of coloring, burning and odor as compared with comparative examples having the same composition.

[0038]

According to the present invention, it is possible to obtain a copolymer resin composition which is less colored and hardly generates a foreign substance discolored from yellowish brown to black, and is useful and applicable to various fields such as light electric appliances and sundries. .

Claims (4)

[Claims] 1. A styrenic monomer and one or more monomers selected from the group consisting of 4,6-bis (octylthiomethyl)
A copolymer resin composition obtained by copolymerization in the presence of -o-cresol, wherein the total of the remaining monomers is 1000 pp
m, which is less than m. (Meth) acrylic acid ester monomer (Meth) acrylic acid (Meth) acrylonitrile 2. When the conversion of the monomer is 30% by mass or more,
The method for producing a copolymer resin composition according to claim 1, wherein 6-bis (octylthiomethyl) -o-cresol is present. 3. When the conversion of the monomer is 30% by mass or more,
3. The method for producing a copolymer resin composition according to claim 2, wherein after the presence of 6-bis (octylthiomethyl) -o-cresol, 2% by mass or more is copolymerized. 4. A copolymer resin composition obtained by the method according to claim 2.