JPH04275356A - Antistatic thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain an antistatic thermoplastic resin composition having excellent weld strength and permanent antistatic performance. CONSTITUTION:100 pts.wt. total amount of (A) 92-50 pts.wt. rubber reinforced styrenic resin (e.g. ABAS resin or MBS resin), (B), 3-30 pts.wt. polyethylene oxide having preferably >=1,500,000, preferably 2,000,000-4,000,000 average molecular weight and (C) 5-45 pts.wt. metacrylic resin is blended with (D) 0-5 pts.wt. alkali metal salf (e.g. lithium chloride or lithium bromide).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic rubber-reinforced styrenic resin composition having good weld strength and permanent antistatic properties.

0002

[Prior art and problems] ABS resin and HIPS
Rubber-reinforced styrene resins such as (high-impact polystyrene) have excellent moldability, a balance between impact strength and rigidity, and the appearance of molded products, and are widely used as materials for automobile parts, electrical products, office equipment, etc.

However, like other plastics, rubber-reinforced styrene-based resins are easily charged with electricity, and dirt and dust are attracted to the surface of the molded product, damaging the appearance of the molded product.In addition, in the case of electronic equipment, the charged electricity can cause damage. There was a problem of giving.

[0004] As a conventional antistatic method, it is common to add an antistatic agent to a rubber-reinforced styrene resin, but this method has a problem in that the antistatic effect is insufficiently durable.

On the other hand, recently, there have been many methods to provide a long-lasting antistatic effect by polymer alloying with hydrophilic resins (for example, polyamide elastomers) (for example, Japanese Patent Laid-Open No. 60-23435). ), these alloy types have the disadvantage that the strength of the weld part of the injection molded product is weak, which poses a practical problem.

[0006]

[Means for Solving the Problems] The present inventors have investigated a method of imparting permanent antistatic properties to rubber-reinforced styrene-based resins, as well as providing strength to the weld parts. The present invention has been achieved by discovering that the above object can be achieved by blending polyethylene oxide, methacrylic resin, and, if necessary, alkali metal salt into the resin in specific proportions.

That is, the present invention comprises 92 to 50 parts by weight of a rubber-reinforced styrene resin (A), 3 to 30 parts by weight of polyethylene oxide (B) having an average molecular weight of 1.5 million or more, and 5 to 45 parts by weight of a methacrylic resin (C). The object of the present invention is to provide an antistatic thermoplastic resin composition having good strength in the weld portion, which is made by blending 0 to 5 parts by weight of an alkali metal salt (D) with respect to the total amount of 100 parts by weight.

Rubber-reinforced styrenic resin used in the present invention (
A) is composed of a rubber component and a styrene resin component, and is generally a graft polymer formed by polymerizing a styrene monomer and other copolymerizable monomers in the presence of a rubber component. mixture (i), a mixture (ii) of a graft polymer (i) and a (co)polymer obtained by polymerizing a styrenic monomer or a styrene monomer and another copolymerizable monomer; or Mixture (iii) of a rubber component and the above-mentioned (co)polymer
Consisting of

ABS resin (acrylonitrile-butadiene rubber-styrene copolymer), MBS resin (methyl methacrylate-butadiene rubber-styrene copolymer)
, AES resin (acrylonitrile-ethylene/propylene rubber-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), HI
Products traded under names such as PS (butadiene rubber-styrene copolymer) are rubber-reinforced styrene resins (A
), especially ABS resin, AES resin, AA resin
S resin is preferred.

As the rubber component, diene rubbers such as polybutadiene, polyisoprene, butadiene-styrene copolymer, isoprene-styrene copolymer, butadiene-acrylonitrile copolymer, butadiene-isoprene-styrene copolymer, and polychloroprene are used. , ethylene-propylene rubber such as ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and acrylic rubber such as polybutyl acrylate.

[0011] Furthermore, examples of the styrene monomer used in the above-mentioned graft polymer and (co)polymer include styrene, α-methylstyrene, para-methylstyrene, etc., and one or more of them can be used. I can do it. Particularly preferred are styrene and α-methylstyrene.

Other copolymerizable monomers that can be used with the styrene monomer include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, and (meth)acrylic compounds such as methyl methacrylate and methyl acrylate. Examples include acid ester compounds, maleimide compounds such as N-phenylmaleimide and N-cyclohexylmaleimide, and one or more types of each can be used.

In view of the physical property balance of the final composition, the styrene monomer (2) is added in the presence of one or more rubbers (1) selected from the group consisting of diene rubber, ethylene-propylene rubber, and acrylic rubber. ) and vinyl cyanide compounds,
A graft polymer obtained by polymerizing one or more other copolymerizable monomers (3) selected from the group consisting of (meth)acrylic acid ester compounds and maleimide compounds, and the above monomer (2) and ( A rubber-reinforced styrenic resin which is a mixture with a copolymer obtained by polymerizing 3) is preferred.

Polyethylene oxide (
B) may have an average molecular weight of 1.5 million or more. If the average molecular weight is less than 1,500,000, the weld strength decreases, which is not preferable. Preferably, the average molecular weight is 1.7 million to 50
00,000, more preferably 2,000,000 to 4,000,000. Incidentally, the average molecular weight here is a viscosity average molecular weight, and in detail, it is determined by the following formula, measured by the Ostwald viscosity system (35° C.).

[0015]

[Equation 1] [η] = 6.4 × 10-5M0.82

00
16] Here, [η] is the intrinsic viscosity of polyethylene oxide, and M is its average molecular weight.

The methacrylic resin in the present invention is a homopolymer of an alkyl methacrylate ester or a copolymer mainly composed of an alkyl methacrylate ester. The methacrylic acid alkyl ester is a methacrylic acid alkyl ester having a C1-4 alkyl group, such as methyl methacrylate and ethyl methacrylate. Compounds copolymerized with methacrylic acid alkyl esters include acrylic acid alkyl esters such as ethyl acrylate and butyl acrylate, aromatic vinyls such as styrene and α-methylstyrene, and vinyl cyanides such as acrylonitrile and methacrylonitrile. Can be mentioned. Preferably, it is a copolymer containing 50% by weight or more of methyl methacrylate, and more preferably a copolymer containing 80% by weight or more of methyl methacrylate or a homopolymer of methyl methacrylate.

The composition of the rubber-reinforced styrene resin (A), polyethylene oxide (B), and methacrylic resin (C) is (A) 92 to 50 parts by weight, (B) 3 to 30 parts by weight, and (C) 5 parts by weight. ~45 parts by weight. However, (A)
, (B) and (C) is 100 parts by weight.

If the rubber-reinforced styrenic resin (A) is less than 50 parts by weight, the weld strength and notched Izod impact strength will decrease, and if it exceeds 92 parts by weight, the antistatic properties will be poor, which is not preferable. The amount of rubber reinforced styrene resin used is preferably 89 to 55 parts by weight, preferably 86 to 6 parts by weight.
It is 0 parts by weight.

If the amount of polyethylene oxide is less than 3 parts by weight, the antistatic properties of the composition will be poor, and if it exceeds 30 parts by weight, the weld strength of the composition will decrease, which is not preferable. The amount of polyethylene oxide used is preferably 5 to 20 parts by weight, more preferably 7 to 15 parts by weight.

If the methacrylic resin is less than 5 parts by weight, the effect of improving weld strength is small, and if it exceeds 45 parts by weight, the notched Izod impact strength is undesirably lowered. The amount of methacrylic resin used is preferably 6 to 40 parts by weight, more preferably 7 to 35 parts by weight.

The alkali metal salt (D) of the present invention includes:
Lithium chloride, lithium bromide, lithium iodide, sodium iodide, sodium borohydride, lithium borofluoride, potassium borofluoride, lithium tetraphenylborate, potassium tetraphenylborate, sodium tetraphenylborate, lithium thiocyanate, Alkali metal salts of inorganic acids such as sodium thiocyanate, potassium thiocyanate, lithium perchlorate, sodium perchlorate, potassium perchlorate, lithium trifluoroacetate, sodium trifluoroacetate, potassium trifluoroacetate, trifluoromethanesulfonic acid Lithium, sodium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, lithium acetate, sodium acetate, potassium acetate, lithium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, lithium dodecylsulfonate, potassium dodecylsulfonate , alkali metal salts of organic acids such as sodium dodecyl sulfonate, and one kind or two or more kinds thereof may be used in combination. Among these alkali metal salts, preferred are alkali metal salts of nuclear-substituted benzenesulfonic acids such as dodecylbenzenesulfonic acid and potassium thiocyanate.

The amount of the alkali metal salt (D) used is determined by the amount of the rubber-reinforced styrenic resin (A), polyethylene oxide (
The amount is 0 to 5 parts by weight based on 100 parts by weight of the total amount of B) and methacrylic resin (C). Although there is a certain antistatic property even without an alkali metal salt, the antistatic property is further improved by using it. In addition, even if the alkali metal salt exceeds 5 parts by weight, the antistatic properties of the composition will not improve any further, and on the other hand, the dispersibility will worsen, and it may precipitate on the surface of the molded product, impairing its appearance, or causing the surface to deteriorate. It is undesirable because it becomes sticky. The amount of alkali metal salt used is preferably 0.
It is 1 to 3 parts by weight.

The antistatic thermoplastic resin composition of the present invention includes:
Antioxidants [e.g. 2,6-di-t-butyl-4-methylphenol, 2-(1-methylcyclohexyl)-4
, 6-dimethylphenol, 2,2-methylene-bis-
(4-ethyl-6-t-methylphenol), 4,4'
-thiobis-(6-t-butyl-3-methylphenol), dilaurylthiodipropionate, tris(di-nonylphenyl)phosphite, wax], UV absorbers [e.g. pt-butylphenyl salicylate, 2 ，
2'-dihydroxy-4-methoxybenzophenone, 2
-(2'-hydroxy-4'-n-octoxyphenyl)benzotriazole], lubricants [e.g. paraffin wax, stearic acid, hydrogenated oil, stearamide, methylene bis stearamide, ethylene bis stearamide,
n-butyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride], flame retardants [e.g., antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, tris(dichloropropyl) phosphate,
Chlorinated paraffin, tetrabromobutane, hexabromobenzene, tetrabromobisphenol A], colorant [
For example, titanium oxide, carbon black], fillers (for example, calcium carbonate, clay, silica, glass fiber, glass spheres, carbon fiber), pigments, etc. can be added as necessary.

Furthermore, in the present invention, there is no hindrance to the combined use of other antistatic agents.

The composition of the present invention may further contain other thermoplastic resins such as polycarbonate, polyvinyl chloride, polyamide, polybutylene terephthalate, polyethylene terephthalate, polyphenylene oxide, and polyoxymethylene, if necessary. can.

Next, the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

[0028] All parts in the compounding composition are by weight. In addition, the physical properties of the composition were measured as follows.

(1) Preparation of test pieces for measuring physical properties The pellets obtained in the Examples and Comparative Examples were molded into test pieces for each physical property using a 3.5-ounce injection molding machine at a cylinder temperature of 220°C.

(2) Measurement of physical properties (i) Notched Izod impact strength Conforms to ASTM D-256. (1/4 inch thick) 23℃

(ii) Weld strength Using a test piece molded using a mold with gates at both ends to form a weld in the center of an ASTM No. 1 dumbbell, it was tested using a bending tester with a distance between supports of 50 mm and a crosshead. ASTM
A bending test was conducted in accordance with D-790, and the stress at break was evaluated as weld strength.

(iii) Surface resistance value A flat plate of 90 x 40 x 3 mm was used for measurement under the following conditions. (a) Measure the test piece after conditioning it for 24 hours at 23°C and 55% relative humidity. (b) After thoroughly washing the surface of the test piece with pure water,
Measurements are taken after conditioning for 24 hours at 55% relative humidity. The surface resistance value was measured using a surface high resistance meter SM-10E (manufactured by Toa Denpa Kogyo Co., Ltd.) under conditions of a measurement voltage of 100 V and a sampling time of 10 seconds.

(iv) Appearance After being left in the injection mold for 5 minutes, the molding was performed and the appearance was evaluated.

Example 1 Rubber content: 15 consisting of a graft polymer obtained by polymerizing styrene and acrylonitrile in the presence of polybutadiene and a copolymer obtained by polymerizing styrene and acrylonitrile.
% ABS resin, 10 parts of polyethylene oxide with an average molecular weight of 2 million, 30 parts of Sumipex B-MH (polymethyl methacrylate, manufactured by Sumitomo Chemical Co., Ltd.) as a methacrylic resin, and 2 parts of sodium dodecylbenzenesulfonate were vented. After kneading at a cylinder temperature of 220° C. using a 40 mm single-screw extruder, the mixture was pelletized. The physical properties of the obtained composition were measured by the method described above. The results are shown in Table 1.

Comparative example 1 The physical properties of the ABS resin used in Example 1 were measured in the same manner. The results are shown in Table 1.

Comparative Example 2 100 parts of the ABS resin used in Example 1 was mixed with 2 parts of sodium dodecylbenzenesulfonate, then pelletized in the same manner as in Example 1, and the physical properties were measured. The results are shown in Table 1.

Comparative Example 3 After mixing the ABS resin used in Example 1 with polyethylene oxide and sodium dodecylbenzenesulfonate in a composition of 90 parts/10 parts/2 parts, pelletization was performed in the same manner as in Example 1, and the physical properties were determined. was measured. The results are shown in Table 1.

Examples 2, 3, 4, 5, 6, 7 and Comparative Examples 4, 5, 6, 7 In Example 1, the blending composition of ABS resin, polyethylene oxide, and methacrylic resin was 70 parts/70 parts each.
10 copies/20 copies, 80 copies/10 copies/10 copies, 50 copies/1
0 copies/40 copies and 65 copies/5 copies/30 copies, 55 copies/1
5 copies/30 copies, 50 copies/20 copies/30 copies, and 87 copies/
The numbers were changed to 10 parts/3 parts, 40 parts/10 parts/50 parts, 69 parts/1 part/30 parts, and 30 parts/40 parts/10 parts. The other ingredients were blended in the same manner as in Example 1, and the physical properties of each composition were measured. The results are shown in Table 1.

Examples 8, 9, 10 and Comparative Example 8 Example 1 was repeated except that the amount of sodium dodecylbenzenesulfonate added was changed to 0 parts, 1 part, 5 parts, and 8 parts, respectively. It was mixed in the same way. The physical properties of each composition were measured and shown in Table 1.

Example 11 A mixture was prepared in the same manner as in Example 1, except that 0.5 parts of potassium thiocyanate was used instead of 2 parts of sodium dodecylbenzenesulfonate, and the physical properties were measured. The results are shown in Table 1.

Example 12 and Comparative Example 9 In Example 1, the molecular weight of polyethylene oxide was 50
The blending was carried out in the same manner as in Example 1, except that the amounts were changed to 0,000,000 and 300,000. The physical properties of each composition were measured and shown in Table 1.

Example 13 In Example 1, a graft polymer obtained by polymerizing styrene and acrylonitrile in the presence of EPDM (ethylene propylene ethylidene norbornene rubber) in place of the ABS resin, and a graft polymer obtained by polymerizing styrene and acrylonitrile. Blending was performed in the same manner as in Example 1, except that an AES resin consisting of a copolymer and having a rubber content of 17% was used, and the physical properties were measured. The results are shown in Table 1.

[0043]

[Table 1]

[0044]

Effects of the Invention The rubber-reinforced styrenic resin composition of the present invention exhibits better antistatic properties even after washing with water, compared to a composition containing an ordinary antistatic agent (Comparative Example 2), and its sustainability is is excellent. Moreover, the Izod impact strength is also good. On the other hand, if methacrylic resin (C) is not added (Comparative Example 3) or if it is less than 5 parts (Comparative Example 4), the weld strength will be insufficient, and if it exceeds 45 parts (Comparative Example 5), the Izod impact strength will be insufficient. Insufficient and undesirable. Furthermore, if the amount of polyethylene oxide (B) is less than 3 parts, the antistatic property after washing will be insufficient (Comparative Example 6), and if it exceeds 30 parts (Comparative Example 7), the weld strength will decrease, which is not preferable. Furthermore, when the amount of the alkali metal salt added exceeds 5 parts (Comparative Example 8), the surface appearance is significantly deteriorated, which is not preferable. Moreover, when the molecular weight of polyethylene oxide (B) is less than 1.5 million (Comparative Example 9), Izod impact strength and weld strength are undesirably lowered.

Claims (1)

[Claims] [Claim 1] Rubber reinforced styrenic resin (A) 92~
50 parts by weight, 3 to 30 parts by weight of polyethylene oxide (B) having an average molecular weight of 1.5 million or more, and 5 to 45 parts by weight of methacrylic resin (C) for a total of 100 parts by weight,
An antistatic thermoplastic resin composition containing 0 to 5 parts by weight of an alkali metal salt (D).