JPH0673263A - Styrenic resin composition - Google Patents

Abstract

PURPOSE:To obtain a styrenic resin compsn. excellent in antistatic properties, molded appearance, and impact resistance by compounding a styrenic resin, an alkylene oxide polymer, a modified vinyl polymer, and an alkali metal salt. CONSTITUTION:This resin compsn. is prepd. by compounding 100 pts.wt. polymer component comprising 40-94 pts.wt. styrenic resin, 5-30 pts.wt. alkylene oxide polymer having ethylene oxide units, and 1-30 pts.wt. modified vinyl polymer having at least one kind of functional group selected from the group consisting of a carbonyl group, an epoxy group, and a polyoxyalkylene group having a mol.wt. of 300-2,000 or its deriv. with 0.01-7 pts.wt. alkali metal salt. The addition of the modified vinyl polymer and the salt to the former two resins gives the objective styrenic resin compsn. having high mechanical strengths and permanent antistatic properties at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrenic resin composition having permanent antistatic properties, impact resistance and molding appearance.

[0002]

2. Description of the Related Art Currently, many thermoplastic resins are widely used. Among them, ABS resins and styrene resins represented by high-impact polystyrene are
It has features such as low cost, good moldability, excellent molding appearance, and free coloring, and its applications are being further expanded. However, a common property of many thermoplastic resins is that they are easily charged by static electricity. Styrene-based resins are no exception, and are electrostatically charged to attract dust. Further, when such a resin is used in a case of electric / electronic equipment, static electricity may cause malfunction of the equipment, or in the worst case, damage of the equipment.

As a means for preventing the static electricity of the resin, a method of kneading the resin with an antistatic agent, a conductive metal powder or carbon black is used. However, if you knead metal powder or carbon black into the resin,
The mechanical strength such as impact strength of the styrene resin is poor, and the resin cannot be colored freely. Therefore, kneading an antistatic agent with a resin is widely performed. As the antistatic agent, when a low molecular weight one is kneaded, the antistatic property is removed by wiping with cloth or washing with water, so that a high molecular weight agent is often used.

Japanese Patent Laid-Open Nos. 60-23435 and 6
Japanese Laid-Open Patent Publication No. 1-246244 proposes a method of kneading a polyether ester amide with a resin, and although the resin exhibits permanent antistatic property, these resins exhibit remarkable delamination, and JP-A-62-241945. JP-A-62-250049, JP-A-63-95251 and the like disclose a method of obtaining a resin having a good layered releasability by modifying the resin. In this method, the resin is bent. It is not preferable because the elastic modulus becomes insufficient.

Japanese Unexamined Patent Publication No. 64-26674 discloses a method of using an alkylene oxide polymer as an antistatic agent. With this method, a resin having a high flexural modulus can be obtained, but the resin is delaminated.
Further, in Japanese Patent Laid-Open No. 3251/1993, the delamination of the resin is remarkably reduced by the carboxylic acid modification, but if the polyether is added in an amount sufficient to obtain good antistatic property, the hardness of the resin becomes insufficient. There was a problem of being lost.

[0006]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention have conducted extensive studies to provide a styrene resin which is inexpensive, has excellent mechanical strength, and has permanent antistatic properties. The present inventors have found that the above problems can be solved by adding a specific modified vinyl polymer and an alkali metal salt in a blend of a polyalkylene oxide and a polyalkylene oxide.

[0007]

According to the present invention, 40 to 94 parts by weight of a styrene resin (A) and an alkylene oxide polymer (B) 5 containing an ethylene oxide unit as an essential component are used.
30 parts by weight, carbonyl group, epoxy group, molecular weight 300
1 to 30 parts by weight of (A) +, a modified vinyl copolymer (C) having at least one functional group selected from polyalkylene oxide groups of 2,000 to 2,000 or derivatives thereof.
It is a styrene-based resin composition in which 0.01 to 7 parts by weight of the alkali metal salt (D) is added to the resin composition in which the total of (B) + (C) is 100 parts by weight.

The feature of the present invention is that the styrene resin (A) and the alkylene oxide polymer (B) are added to a specific modified vinyl copolymer to obtain impact resistance, flexural modulus and hardness of the resin. Is appropriately compatibilized without deteriorating, and the addition of an alkali metal salt remarkably improves the antistatic property, and the antistatic property also has the durability not to be lost by washing with water.

Since the styrene resin (A) and the alkylene oxide polymer (B) are incompatible systems, when only these two are kneaded and molded, the resin remarkably delaminates. However, when a polymer compatible with both of these is added, delamination is significantly reduced. The state of delamination depends largely on the molecular structure of the polymer (C) such as the ratio of the vinyl monomer to the functional group in the modified vinyl polymer (C) and the molecular weight of the polyalkylene oxide group. To do.

The present invention will be specifically described below.
Any styrene resin (A) that can be used in the present invention can be used as long as it contains styrene as an essential component. For example, polystyrene, high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer resin (AB
S resin), acrylonitrile-styrene resin (AS resin), (meth) acrylic acid ester-butadiene-styrene copolymer resin (MBS resin), acrylonitrile-acrylic rubber-styrene copolymer resin (ASA resin), acrylonitrile-EPDM- Styrene resin (AES resin) or the like is used. Usual emulsion polymerization, suspension polymerization, solution polymerization, emulsion solution polymerization and the like can be used as the production method thereof, but the production method is not particularly limited.

As the alkylene oxide polymer (B), an ethylene oxide unit is an essential component, and 5 ethylene oxide units are contained in the alkylene oxide polymer.
Those containing 0% by weight or more are preferable. When the ethylene oxide unit is less than 50% by weight, the antistatic property of the resin becomes insufficient, which is not preferable. The molecular weight of the alkylene oxide polymer (B) is 10,000 to 2,000,000.
Those having less than 10,000 are preferable, and the melt viscosity of the alkylene oxide polymer is too low to improve delamination, and those having more than 2,000,000 cause fish eyes. This is not preferable because the appearance of resin molding becomes poor. As the component other than the ethylene oxide unit, for example, propylene oxide,
Butylene oxide, epichlorohydrin, tetrahydrofuran, etc. can be used. In particular, a homopolymer of ethylene oxide or a copolymer of ethylene oxide and propylene oxide having an ethylene oxide unit content of 70% by weight or more is preferably used. The polymerization method is also not particularly limited, but solution polymerization using an alkali metal catalyst is preferably used.

The modified vinyl-based copolymer (C) has a carbonyl group, an epoxy group and a molecular weight of 300 to 300 in the molecular chain.
A vinyl copolymer having at least one functional group selected from 2,000 polyalkylene oxide groups or derivatives thereof is used. The modified vinyl-based copolymer (C) is obtained by copolymerizing one or more vinyl-based monomers with a monomer having the above functional group, and has a carbonyl group in its molecule. , An epoxy group, a polyalkylene oxide group having a molecular weight of 300 to 2,000, or a derivative thereof, at least one functional group. The method of introducing these functional groups into the molecule is not particularly limited, and for example, one or more vinyl-based monomers are copolymerized with a carbonyl group, an epoxy group, and a vinyl-based monomer having the polyalkylene oxide group. Or a vinyl-based monomer having a functional group other than the carbonyl group, the epoxy group, and the polyalkylene oxide group, and the copolymer is modified to modify the carbonyl group, the epoxy group, and the polyalkylene. You may introduce an oxide group.

As a specific method for introducing a carbonyl group, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid and itaconic acid and their esters are copolymerized with a predetermined vinyl monomer. A method is used. As a method for introducing an epoxy group, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, etc. are copolymerized with a predetermined vinyl monomer, and a copolymer of acrylic acid ester or methacrylic acid ester is transesterified. A method of introducing a glycidyl group or the like is used. As a specific method of introducing a polyalkylene oxide group, a method of copolymerizing a polyalkylene oxide having a reactive vinyl unit at a terminal such as polyalkylene oxide monomethacrylate with a predetermined vinyl-based monomer, or acrylic acid Alternatively, a method of reacting or transesterifying at least one end of a polyalkylene oxide having a hydroxyl group with a copolymer of acrylic acid ester, methacrylic acid, or methacrylic acid ester can be used.

The polyalkylene oxide unit used herein preferably has a molecular weight of 300 to 2,000. When it is less than 300, delamination of the resin is not improved, and when it exceeds 2,000, the resin is molded. It is not preferable because the appearance is deteriorated. The amount of polyalkylene oxide in the modified vinyl copolymer (C) is preferably 20 to 80% by weight, and if it deviates from this range, the resin is delaminated, which is not preferable.

As the vinyl-based monomer, aromatic vinyl-based monomers, vinyl cyanide-based monomers, (meth) acrylic acid ester-based monomers, maleic acid derivatives and the like can be used. Specific examples thereof include styrene, acrylonitrile, methyl methacrylate, maleic anhydride, N-phenylmaleimide, and derivatives thereof. The specific ratio of these monomers is, for the purpose of improving the compatibility between the styrene resin (A) and the alkylene oxide polymer (B),
The same or similar to the styrene resin (A), or a composition having compatibility with each other is selected.

The alkali metal salt (D) may be either an inorganic or organic alkali metal salt, preferably an organic alkali metal salt, and more preferably a combination thereof. By adding a minute amount of the inorganic alkali metal salt in the presence of the alkylene oxide polymer, the antistatic property of the resin is remarkably improved. In the absence of the alkylene oxide polymer, the antistatic property is not expressed. Therefore, it is considered that the interaction between the alkylene oxide and the alkali metal ion causes the ion to move in the resin, which improves the conductivity.

As the inorganic alkali metal salt, any kind of inorganic alkali metal salt shows a slight improvement, but a strong acid alkali metal salt or alkaline earth metal salt is preferably used. Specifically, halides, cyanides, thiocyanides, borofluorides, perchlorates, hexafluorophosphates and the like are used. More preferably, thiocyanate is used. The addition amount is preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the resin. When the metal salt is present in the resin in an amount of 0.01 part by weight or more, the effect is exhibited, and the antistatic property of the resin is improved as the number of added parts increases.
If the amount exceeds the above range, color burning or decomposition occurs when the resin is heated to a high temperature, which is not preferable.

As the organic alkali metal salt, those which are generally widely used as a surfactant can be used. For example, a sulfonate represented by a fatty acid salt, an alkyl sulfonate, an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, a polyoxyethylene alkyl ether sulfonate and the like can be used. Preferred is a sulfonate. Specifically, sodium octyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium cetyl sulfonate, sodium stearyl sulfonate, sodium octyl benzene sulfonate, sodium decyl benzene sulfonate, sodium dodecyl benzene sulfonate, stearyl benzene sulfonate. Sodium acid salt, sodium dodecylnaphthalene sulfonate and the like, and lithium salt or potassium salt thereof are used.

In the absence of alkylene oxide polymer,
When an organic alkali metal salt is added, it exhibits antistatic properties, but this is not permanent so as not to be lost by washing with water. In the presence of the alkylene oxide polymer, it exhibits better permanent antistatic properties than in the case where the polymer and the organic alkali metal salt are used alone. It is considered that this is the same mechanism as when the inorganic alkali metal salt is added.

The number of parts of the organic alkali metal salt added is
0.1 to 5 parts by weight is preferable. If it is less than 0.1 part by weight, good antistatic property is not exhibited, and if it exceeds 5 parts by weight, the molding appearance of the resin is deteriorated and the alkali metal salt bleeds out from the resin, which is not preferable.

These inorganic or organic alkali metal salts are
Of course, each of them may be used alone, but by using them together, the antistatic property can be further improved.
That is, the addition amount of the alkali metal salt (D) is 0.0
1 to 7 parts by weight is preferable.

In this way, the styrene resin (A) 40
~ 94 wt%, alkylene oxide polymer (B) 5 ~
30% by weight, carbonyl group, epoxy group, molecular weight 300
Alkali metal salt to 100 parts by weight of a composition comprising 1 to 30% by weight of a modified vinyl polymer (C) having at least one functional group selected from a polyalkylene oxide group or a derivative thereof of 2,000 to 2,000. (D) 0.01
The antistatic styrene resin composition of the present invention can be obtained by adding the antistatic styrenic resin composition in an amount of about 7 to 7 parts by weight. When the styrene resin (A) is less than 40% by weight, mechanical strength such as impact resistance of the resin is poor, and when it exceeds 94% by weight, antistatic property after washing with water is insufficient, which is not preferable. Similarly, when the amount of the alkylene oxide polymer (B) is less than 5% by weight, the antistatic property after washing with water is insufficient, and when it exceeds 30% by weight, the mechanical strength of the resin is inferior and delamination occurs.
When the content of the modified vinyl polymer (C) is less than 1% by weight, the resin is delaminated, and when it exceeds 30 parts by weight, the appearance of the resin is deteriorated, which is not preferable. Alkali metal salt (D) is 0.
When it is less than 01% by weight, the antistatic property of the resin is poor,
If it exceeds 7% by weight, the resin is color burned and bleeds out, which is not preferable.

The method for producing the styrene resin composition of the present invention is not particularly limited, and examples thereof include styrene resin (A) and alkylene oxide polymer (B), modified vinyl polymer (C), alkali metal salt. (D) is mixed,
A molded product can be obtained by a method such as injection molding after kneading with a vent type extruder or roll to form pellets or sheets.

At this time, in order to further improve the performance as a molding material, another antistatic agent such as a cation type or nonionic type is added to further improve the antistatic property,
In order to further improve the thermal stability, it is possible to add an antioxidant or a thermal stabilizer, and if necessary, a lubricant or a plasticizer, a dye or a pigment, a compatibilizer, a flame retardant, an ultraviolet absorber or the like. .

[0025]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples. In addition, "%" in Examples and Comparative Examples,
"Part" means "% by weight" and "part by weight", respectively.

The styrene resin composition of the present invention was prepared by mixing a styrene resin, an alkylene oxide polymer, a modified vinyl polymer and an alkali metal salt and pelletizing the mixture with a vent type extruder. A resin test piece was prepared from this using an injection molding machine, and various physical properties were measured by the following test methods.

(1) Izod impact strength: ASTM D
-256 (with a 1/4 "thickness notch). (2) Flexural modulus: measured according to ASTM D-790. (3) Vicat softening point temperature: According to ISO R-306. (4) Surface resistivity: resin was molded on a flat plate of 40 mm × 50 mm × 4 mm and measured at room temperature of 23 ° C. and relative humidity of 50% The measurement was made by Toa Denpa Kogyo Co., Ltd. SM-1
A OE resistance meter was used. The value 1 minute after the application was measured at a voltage of 500V. The measurement was performed after conditioning for 24 hours after molding under conditions of 23 ° C. and relative humidity of 50%. As a permanent antistatic test, the surface of the test piece was rubbed 20 times in a large amount of pure water with gauze to remove water on the surface with a filter paper, and the test piece was held at 23 ° C. for 4 hours. The measurement was performed again after the humidity was adjusted under the condition of relative humidity of 50%. Subsequently, the surface resistivity was measured after standing for 1 month in an environment of 23 ° C. and 50% relative humidity.

(5) Charge voltage and its half-life: A static Honest meter manufactured by Shishido Trading Co.
A voltage of 5 kV was applied to the resin for 30 seconds, and the voltage at which the resin was charged and the time until the voltage was halved were measured. (6) Molding appearance of resin: The appearance (presence or absence of silver, gloss, color) of the above-mentioned molding test piece was visually judged. As for the judgment result, the good appearance of the test piece was ◯, and the bad appearance was x. (7) Layered releasability: The molded test piece was bent many times in the center and the presence or absence of peeling was determined. The judgment results were evaluated as ◯ when the layered releasability was good, and as x when the layered release was performed.

Examples 1 to 14 and Comparative Examples 1 to 9 1) Preparation of styrene resin (A-1) Polybutadiene latex (solid content 50% by weight, average particle diameter 0.28 μm) 30 parts Distilled water 140 parts Acrylonitrile 25 Parts Styrene 60 parts Potassium rosinate 0.9 parts Tertiary decyl mercaptan 0.5 parts Dextrin 0.35 parts Ferrous sulfate 0.01 parts Sodium pyrophosphate 0.2 parts Sodium hydroxide 0.05 parts into a polymerization tank After charging, the temperature was raised to 60 ° C. with stirring. To this, 0.5 part of cumene hydroperoxide was added and polymerized. The yield was 96%. The graft copolymer latex was coagulated with a dilute sulfuric acid aqueous solution, washed with water and dried to obtain a styrene resin (A-1).

2) Preparation of styrene-based resin (A-2) n-butyl acrylate 25 parts distilled water 180 parts potassium rosinate 0.6 parts triallyl cyanurate 0.4 parts was charged into a reaction tank, and under a nitrogen stream. Raise the temperature to 70 ° C. Subsequently, sodium formaldehyde sulfoxylate 0.3 part Ferrous sulfate / heptahydrate 0.01 part Tolylenediamine disodium disodium 0.03 part Cumene hydroperoxide 0.2 part was added to initiate polymerization. . After 150 minutes, a mixture of 35 parts of methyl methacrylate, 40 parts of styrene and 0.3 parts of cumene hydroperoxide was added dropwise over 45 minutes for graft polymerization. After completion of dropping, the mixture was stirred for 1 hour as it was to obtain a graft copolymer latex. The latex was coagulated with a sulfuric acid aqueous solution, washed with water and dried to obtain a white powder of styrene resin (A-2). The yield was 93%.

3) Alkylene oxide polymer (B-
1) Polyethylene oxide (molecular weight 300,000: manufactured by Meisei Kasei Co., Ltd.) was used (B-1).

4) Preparation of alkylene oxide polymer (B-2) Ethylene oxide 85 parts Propylene oxide 15 parts Normal hexane (anhydrous) 100 parts Potassium hydroxide 0.2 parts Charged in an autoclave at 50 ° C. for 3 hours. , 60
Polymerization was performed at ℃ for 3 hours. After cooling, the solvent was removed under reduced pressure to give a white lump of alkylene oxide polymer (B-2).
Got The yield was 95% and the average molecular weight was 250,000.

5) Alkylene oxide polymer (B-
3) An alkylene oxide polymer (B-3) was prepared by polymerizing in the same manner as in (B-2) except that 40 parts of ethylene oxide and 60 parts of propylene oxide were used. Yield 8
It was 8% and the average molecular weight was 3,000,000.

6) Preparation of modified vinyl polymer (C-1) Methyl methacrylate 100 parts Distilled water 120 parts Tertiary dodecyl mercaptan 0.45 parts Azobisisobutyronitrile 0.15 parts Calcium phosphate 0.40 parts Suspension polymerization was carried out at 75 ° C under a nitrogen stream, and the resulting polymer was washed with water and dried to give a white granular modified vinyl polymer (C-
1) was prepared. The yield was 90%.

7) Preparation of Modified Vinyl Polymer (C-2) Acrylonitrile 20 parts Styrene 45 parts N-Phenylmaleimide 35 parts Tertiarydodecyl mercaptan 0.2 parts Azobisisobutyronitrile 0.1 part Continuous mass The dope thus formed was sent to an extruder to prepare a modified vinyl polymer (C-2) in the form of colorless pellets. The yield was 97%.

8) Preparation of Modified Vinyl Polymer (C-3) Acrylonitrile 25 parts Styrene 70 parts Glycidyl Methacrylate 5 parts Distilled Water 120 parts Tertalide Decyl Mercaptan 0.42 parts Azobisisobutyronitrile 0.12 parts 0.4 parts of calcium phosphate was subjected to suspension polymerization at 75 ° C. under a nitrogen stream, and the resulting polymer was washed with water and dried to give a white granular modified vinyl polymer (C-
3) was prepared. The yield was 88%.

9) Preparation of modified vinyl polymer (C-4) Polyethylene glycol monomethacrylate (number of ethylene oxide units is 23: manufactured by Shin-Nakamura Chemical Co., Ltd.) 40 parts Methyl methacrylate 20 parts Styrene 40 parts Methyl ethyl ketone 120 Parts n-octyl mercaptan 0.2 parts azobisisobutyronitrile 0.4 parts were charged into a reaction tank and polymerized at 60 ° C. for 4 hours. This polymerization solution was dried under reduced pressure to remove methyl ethyl ketone, and a white crystalline modified vinyl polymer (C-4) was obtained. Yield is 9
It was 0%.

The styrene resin (A), the alkylene oxide polymer (B), the modified vinyl polymer (C) and the alkali metal salt (D) prepared as described above are shown in Table 1.
Blended with the composition described in 1., mixed with a mixer, and then pelletized using a vented twin-screw extruder, and then pelletized.
A test piece was molded with a z injection molding machine, and the evaluation results are shown in Table 1.

[0039]

[Table 1]

[0040]

From the above results, in the blend of the styrene resin and the alkylene oxide polymer, by adding the modified vinyl polymer and the alkali metal salt, the impact resistance, the appearance of the molded article, and the antistatic property are further improved. It has excellent properties, its antistatic property is permanent without being lost by washing with water, etc., and it is less likely to cause delamination, which is useful in the electrical and electronic fields.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 71:02 101: 06)

Claims (1)

[Claims] 1. A styrene resin (A) 40 to 94 parts by weight, an alkylene oxide polymer (B) containing ethylene oxide as an essential component 5 to 30 parts by weight, a carbonyl group, an epoxy group, and a molecular weight of 300 to 2,000. The modified vinyl-based copolymer (C) having at least one functional group selected from the polyalkylene oxide groups or their derivatives is 1 to 30 parts by weight of (A) + (B) + (C) in total of 100. A styrene-based resin composition in which 0.01 to 7 parts by weight of an alkali metal salt (D) is added to the resin composition which is parts by weight.