JPH0343440A - Antistatic resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition containing a methacrylic resin, a specific polyether and alkali metal salt of an alkyl (benzene) sulfonic acid at a specific ratio, having antistatic properties with an excellent durability and useful for meter cover, housing of electronic equipment, etc. CONSTITUTION:The aimed composition consisting of (A) 100 pts.wt. methacrylic resin, (B) 0.5-20 pts.wt., preferably 2-15 pts.wt. polyether expressed by formula I (R is H or CH3; (n) is integer determined by average molecular weight) and having 2000-3000000, preferably 5000-2000000 average molecular weight and (C) 0.1-5 pts.wt., preferably 0.2-4 pts.wt. alkali metal salt of an alkylsulfonic acid expressed by the formula R-SO3M (R is H or alkyl; M is alkali metal such as Li, Na or K) or an alkali metal salt of alkylbenzene sulfonic acid expressed by formula II (e.g. sodium octyl benzene sulfonate or sodium dodecylbenzene sulfonate).

Description

DETAILED DESCRIPTION OF THE INVENTION C. Industrial Field of Application The present invention relates to a methacrylic resin composition having antistatic properties, and more particularly to a methacrylic resin composition having long-lasting antistatic properties.

[Prior Art and Problems of the Present Invention] Methacrylic resin is used in lighting equipment, signboards, various decorative items, nameplates, etc. due to its excellent transparency, good mechanical properties, workability, and beautiful appearance in molded products. However, methacrylic resin has a property of being easily charged due to its extremely high surface resistivity, which causes flakes to adhere, resulting in poor appearance, poor lighting effects, and poor transparency. It has the disadvantage of causing a decline in optical properties such as.

Conventionally used methods to solve such problems are: (1) applying an antistatic agent to the surface of the molded product;
) A method of kneading an antistatic agent into a thermoplastic superfat material for molding, (3) A method of kneading a conductive filler such as carbon black into a plastic resin material for molding, (4) Chemical modification of the resin structure. There are laws, etc.

However, the resin obtained by method (1) has poor sustainability of the antistatic effect, and there are problems in terms of reliability, such as the antistatic agent falling off or being washed away by running water. On the manufacturing side, a coating process is also required, and the process is difficult. J[It becomes sloppy and productivity decreases. Method (2) does not require a coating process, which solves the problem of reduced productivity, but it also causes contamination of the surface of the molded product due to bleed-out of the antistatic agent mixed in, deterioration of the appearance, and loss of antistatic effect. There were problems such as decline. (
The resin obtained by method 3) has high productivity and can sufficiently reduce the surface resistance value, but it becomes opaque and has a reduced mechanical strength, and the conductive filler mixed in peels off. There is also a risk of contamination of the surrounding area. (
Regarding method 4), for example, a method of copolymerizing MMA and a sulfosuccinate that is copolymerizable with MMA (Japanese Patent Laid-Open No. 59
-182810), a method of copolymerizing MMA and a hydrophilic monomer such as a noble alkyl (meth)acrylate (
JP-A No. 62121717), method of copolymerizing a quaternary ammonium salt monomer with a methacrylic monomer (JP-A No. 62-280248) Copolymerization of MMA and a monomer having a polyalkylene oxide group There is a method of adding an alkali metal salt to a substance (Japanese Unexamined Patent Publication No. 60-42447). Although such a method can achieve semi-permanent antistatic properties, it is necessary to use a large amount of a special hydrophilic monomer in order to achieve sufficient antistatic properties.

Therefore, there are problems in that the beautiful outer shell and colorless transparency inherent to methacrylic resin are easily sacrificed, and the monomers used are expensive, resulting in high costs.

[Means to solve the problem]

The present inventors have conducted intensive research with the aim of providing a thermoplastic resin that maintains the excellent properties of methacrylic resin, has long-lasting antistatic properties, and is inexpensive. The present inventors have discovered that the above object can be achieved by blending a polyether compound with a specific molecular weight and a specific amount of an alkali metal salt of alkylsulfonic acid or alkylbenzenesulfonic acid into a methacrylic resin, and have completed the present invention.

That is, the present invention comprises: (A) 100 parts by weight of a methacrylic resin; (B) an average molecular weight represented by the following general formula of 2.000 to
3.000.000 polyether 0.5 to 20 parts by weight, +CH-CH, -0-h- (However, R is H or CH3, and n is an integer determined by the average molecular weight.) (C) The following formula 0.1 to 5 parts by weight of an alkali metal salt of alkylsulfonic acid or alkylbenzenesulfonic acid represented by R-3○3M (where, -R is H or an alkyl group, and M is an alkali metal such as Li, Na, etc. ) is a methacrylic resin composition having antistatic properties.

A feature of the present invention is that polyether, which itself does not exhibit the practically required level of antistatic properties in the amount used in the present invention, coexists with a metal salt of alkylsulfonic acid or alkylbenzenesulfonic acid. By doing so, it exhibits surprisingly high and long-lasting antistatic properties.

Examples of the methacrylic resin used in the present invention include methyl methacrylate homopolymer, or 50% by weight or more of methyl methacrylate units, styrene, styrene derivatives, vinyl cyanide compounds, acrylic acid, methacrylic acid, acrylic esters, Copolymers consisting of monomer units copolymerizable with methyl methacrylate such as methacrylic acid esters, and furthermore, these (co)polymers and impact resistance imparting agents (e.g. acrylic rubber, butadiene rubber). A composition consisting of:

The average molecular weight used in the present invention is 2,000 to 3,000,
000 polyether has a structural unit represented by the following general formula.

+C1i-CH2-○→T (However, R is hydrogen or a methyl group, and n is an integer determined by the average molecular weight.) Normal polyether has a hydroxyl group at the end of the molecular chain, but both ends or one end are methoxy It is also possible to use derivatives such as those based on bases and those in the form of esters with organic acids such as fatty acids. If the average molecular weight is less than 2.000, the durability of the antistatic property will be poor, and if it exceeds 3,000,000, the appearance will be poor, such as poor color tone, which is not preferred. Specific examples include polyethylene glycol, polyethylene oxide,
Examples include, but are not limited to, polypropylene glycol, polypropylene oxide, methoxypolyethylene glycol, polyethylene glycol monolaurate, and polyethylene glycol monostearate.

The amount used is 0.5 of the polyether having an average molecular weight of 2,000 to 3,000,000, preferably s, ooo to 2,000,000, per 100 parts by weight of the methacrylic resin.
It is necessary to add ~20 parts by weight, preferably 2 to 15 parts by weight. If the amount added is less than 0.5 parts by weight, the antistatic properties will be insufficient, and if it exceeds 20 parts by weight, the heat deformation resistance will be undesirably lowered.

Specific examples of the alkali metal salts (hereinafter abbreviated as metal salts) of alkylsulfonic acids or alkylbenzenesulfonic acids used in the present invention include sodium octylsulfonate, lithium dodecylsulfonate, sodium dodecylsulfonate, and sodium cetylsulfonate. , lithium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium benzenesulfonate, and the like. In particular, alkali metal salts of dodecylbenzenesulfonic acid provide good antistatic properties. The above metal salts may be used alone or in combination of two or more. The amount of the metal salt used is 0.1 to 5 parts by weight, preferably 0.2 to 4 parts by weight, per 100 parts by weight of the methacrylic resin.

If the amount added is less than 0.1 part by weight, antistatic properties will not be sufficient,
If the amount exceeds 5 parts by weight, the appearance of the molded product will be poor, such as decreased transparency, worsened color tone, and stains on the surface of the molded product, which is not preferred.

The method for producing the resin composition of the present invention is not particularly limited. Any method is possible, such as a method of mixing polyether and a metal salt with a methacrylic resin, or a method of pre-mixing a polyether and a metal salt, and then mixing the methacrylic resin at the same time. As a mixing device for each component, a commonly used kneading machine such as a Banbury mixer, a roll, an extruder, etc. can be used.

Further, the resin composition of the present invention may be blended with antioxidants, light stabilizers, lubricants, coloring dyes and pigments, inorganic fillers, organic fillers, and other resins depending on the purpose.

C Effects of the Invention The resin composition of the present invention has excellent antistatic properties and is particularly suitable for electrical equipment parts such as meter covers and nameplates of instruments, lighting equipment covers, housings of electronic equipment, etc. It can be effectively used for various purposes.

〔Example〕

The present invention will be explained in more detail below by way of examples.

Example 1 10 parts of polyethylene oxide having an average molecular weight of 300,000 and 2 parts of sodium dodecylbenzenesulfonate were added to 100 parts by weight of a commercially available methacrylic resin (manufactured by Asahi Kasei Kogyo ■, trade name: Delpet 8ON), and the mixture was placed in a 30 mm twin-screw extruder. The resin was pelletized at a resin temperature of 200'C. The resulting pellets were injection molded in a 3 oz injection molding machine at 220'C;
Test specimens with a thickness of 1/8 inch were obtained. This test piece was heated at 23°C.
After conditioning for 48 hours in a constant temperature room at 150% humidity, the surface resistance value, heat deformation resistance temperature, and haze value were measured. Also,
Regarding the durability of antistatic properties, the molded test piece was immersed in running water for 10 minutes, then vacuum dried at 70°C, and then
Condition B was adjusted in a constant temperature room at 23° C. and 50% humidity, and the surface resistance value was measured. Note that the surface resistance value was measured using a Kyokucho Megohmmeter Model 5M-10E manufactured by Toa Denpa Kogyo Co., Ltd. Also H
DT was measured according to ASTM D64 B. Yellowness was measured using air as a blank.

The results are shown in Table 2.

Examples 2 to 10 and Comparative Examples 1 to 5 Examples were carried out in the same manner as in Example 1 except that the formulation was changed as shown in Table 1. The results are shown in Table 2.

Example 11 As the methacrylic resin (A), a commercially available impact-resistant methacrylic resin [manufactured by Asahi Kakai Kogyo ■, Delpet SR] was used, and Example 1 was used, except that the formulation was changed as shown in Table 1. It was carried out in the same way.

The results are shown in Table 2.

No. table

Claims (1)

[Scope of Claims] 1. (A) 100 parts by weight of methacrylic resin, (B) 0.5 parts of polyether having an average molecular weight of 2,000 to 3,000,000 represented by the following general formula.
~20 parts by weight, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R is H or CH_3, and n is an integer determined by the average molecular weight.) (C) Alkylsulfonic acid or alkylbenzenesulfonic acid represented by the following formula 0.1 to 5 parts by weight of an alkali metal salt of A methacrylic resin composition having antistatic properties.