JPS5938982B2 - Methacrylic resin composition with excellent antistatic properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a methacrylic resin composition with excellent antistatic properties.

Methacrylic resin is used in lighting equipment, due to its excellent transparency, good mechanical properties, processability, and beautiful molded products.
It is widely used for signboards, various decorations, and nameplates, etc., but because its surface resistivity is extremely high, static electricity induced by contact or friction is difficult to dissipate and disappear, so the resin surface during use is Easy to get dirty due to dust etc.
This results in spoiling the beautiful appearance.

Conventionally, as a method of imparting antistatic properties to synthetic resins, many additive kneading methods have been proposed in which surfactants, fatty acid esters of polyhydric alcohols, etc. are added and kneaded. When applied, there is little effect, the molding conditions are restricted, or defects in the appearance of the molded product occur, and even if antistatic performance is imparted, the colorless transparency characteristic of methacrylic resin , the quality of the surface gloss is significantly reduced and it cannot be put to practical use.

Therefore, in order to eliminate the above-mentioned drawbacks, the present inventor proposed a method of first adding higher fatty acid monoglyceride to a methacrylic resin to impart antistatic properties. We proposed a method in which the remaining amount is mixed with the monomer during molding. However, by adopting such a method, excellent antistatic performance can be imparted, but it is necessary to add a large amount to the methacrylic resin, and with this addition amount,
However, they have disadvantages such as lowering the original physical properties of the methacrylic resin and causing problems during extrusion molding due to excessive slipperiness.

The present inventors conducted intensive studies to further improve these drawbacks, and as a result, they discovered that these drawbacks could be solved all at once by forming a special composition, and completed the present invention.

That is, the gist of the present invention is that methacrylic resin [
Copolymer consisting of 100 parts by weight of A], 30 to 90% by weight of an alkali metal salt of methacrylic acid and/or acrylic acid, and 70 to 10% by weight of methyl methacrylate [B] 0.0
3 to 2.0 parts by weight and 2 to 6 parts by weight of higher fatty acid monoglycerade [C] having 8 to 22 carbon atoms, and has excellent antistatic properties.

The methacrylic resin [A] used in the present invention is a methyl methacrylate homopolymer or a copolymer of methyl methacrylate and another copolymerizable monomer.

Other copolymerizable monomers used to produce this copolymer are not particularly limited, but in the present invention, acrylic esters having an alkyl group having 1 to 10 carbon atoms or acrylic esters having 2 to 10 carbon atoms are used. Preferred examples include methacrylic esters having 10 alkyl groups, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. . One or more of these can be used in a mixture with methyl methacrylate up to 20% by weight. The copolymer [B] consisting of an alkali metal salt of methacrylic acid and/or acrylic acid and methyl methacrylate (hereinafter referred to as T1 (meth)acrylate copolymer [B]) used in carrying out the present invention is It is a copolymer obtained by polymerizing 30 to 90% by weight of a metal salt obtained by substituting methacrylic acid and/or acrylic acid with an alkali metal such as lithium, sodium, and potassium, and 70 to 10% by weight of methyl methacrylate.

In this (meth)acrylate copolymer [B], if the amount of the alkali metal salt of methacrylic acid and/or acrylic acid is less than 30% by weight, the affinity with the methacrylic resin becomes too good, resulting in surface migration. If the amount exceeds 90% by weight, the compatibility with methacrylic resin will deteriorate and the surface gloss and transparency of the molded product will deteriorate. This is not preferable in that it causes a decrease in the temperature. Further, the higher fatty acid monoglycerade [C] used in the present invention is a monoester of glycerin and a higher fatty acid having 8 to 22 carbon atoms,
For example, lauric acid monoglyceride, myristic acid monoglyceride, valmitic acid monoglyceride, oleic acid monoglyceride, stearic acid monoglyceride, montanic acid monoglyceride, linoleic acid monoglyceride and behenic acid monoglyceride are preferred. This can be given as an example.

These can be used alone or in combination of two or more types if necessary. (meth) in methacrylic resin composition
The combined use of acrylate copolymer [B] and higher fatty acid monoglyceride [C] does not simply show the additivity of both, but also improves the antistatic performance of methacrylic resin by using both together. A synergistic effect on the antistatic agent was observed, making it possible to significantly reduce the total amount of antistatic agent added.

In addition, (meth)acrylate copolymer [B] is used as a dispersion stabilizer for suspension polymerization of methacrylic acid ester, while higher fatty acid monoglyceride [C] is used as a lubricant for methacrylic resin. Because it is useful,
The resulting methacrylic resin composition has good heat resistance, and even when molded at normal molding temperatures (180°C to 260°C), colorless and transparent molded products that are no different from conventional methacrylic resin molded products can be obtained. be able to.

The ratio of the (meth)acrylate copolymer [B] and higher fatty acid monoglyceride [C] in this composition is based on 100 parts by weight of the methacrylic resin [A].
B] is 0.03 to 2.0 parts by weight, preferably 0.0 to 1 part by weight.
．． 5 parts by weight, and higher fatty acid monoglyceride [
C] is 2 to 6 parts by weight, preferably 3 to 5 parts by weight.

In the methacrylic resin composition, if the (meth)acrylate copolymer [B] is less than 0.03 parts by weight based on 100 parts by weight of the methacrylic resin [A], there is no antistatic effect;
On the other hand, if the amount added exceeds 2 parts by weight, the transparency of the molded product will be significantly impaired and the practicality will be poor due to restrictions on molding processing conditions, which is not preferable. In addition, if the higher fatty acid monoglyceride [C] in the methacrylic resin composition is less than 2% by weight based on 100 parts by weight of the methacrylic resin [A], there is no substantial antistatic effect, and if it exceeds 6 parts by weight, This is not preferable because the extrusion condition width during shaping becomes narrower, which not only causes a decrease in molding processability but also deteriorates the physical properties of the methacrylic resin.

The methacrylic resin composition having antistatic properties according to the present invention is produced by adding and mixing a (meth)acrylate copolymer [B] and a higher fatty acid monoglyceride [C] to methacrylic resin powder, and pelletizing the mixture through an extruder. Alternatively, the additives may be directly added to and mixed with methacrylic resin pellets and molded, or the additives may be dissolved and mixed in monomers in advance and polymerized.

In addition, in the present invention, other additives such as antioxidants, lubricants, ultraviolet absorbers, plasticizers, and various pigments may be added to the composition, if necessary.

Molded articles obtained from the composition of the present invention can be used for meter covers of instruments, name plates, electrical equipment parts, outer frames of spirit levels, and other high-end miscellaneous goods, and can exhibit excellent antistatic effects.

Next, the present invention will be explained in more detail with reference to Examples, in which the middle part of the example indicates parts by weight, and % indicates weight %.

Example 1 For 100 parts of methacrylic resin (manufactured by Mitsubishi Shiyo Corporation, trade name "Acrypet H") [A1],
A copolymer of methyl methacrylate and potassium methacrylate containing 70% potassium methacrylate [B1] and stearic acid monoglyceride [C1] were mixed in the proportions shown in Table 1, and this was mixed in a 40φ extruder. After kneading into pellets at 240'C, the pellets were kneaded at 220°C by a 50Z injection molding machine.
A crest plate (110 x 110 mm) was prepared.

After the molded plate was injection-molded, it was left in a constant temperature room at 23° C. and 5001°C humidity for 3 days, and then the surface resistivity was measured using a ultra-super megohmmeter SM-10 model (manufactured by Toa Denpa Kogyo). Further, after applying a voltage of 10,000 volts to the sample using a static honest meter (manufactured by Shishido Shokai), the applied voltage was reduced to zero, and the time until the charged voltage was halved was measured. The results are shown in Table 1. Example 2 Copolymer of methyl methacrylate and sodium methacrylate containing sodium methacrylate 4001) [B2] and palmitin per 100 parts of methacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trade name [Acrypet MD]) [A2] Acid monoglyceride [C2] was mixed in the composition ratio shown in Table 2, kneaded into pellets at 220°C using a 40φ extruder, and then pelletized at 210°C using a 50Z injection molding machine.
A 2 mm plate (110 x 110 mm) was prepared.

The surface resistivity and half-life of the obtained molded plate were measured in the same manner as in Example 1. The results are shown in Table 2. Example 3 A copolymer consisting of 30% potassium acrylate, 30% potassium methacrylate, and 40% methyl methacrylate based on 100 parts of methacrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., trade name "Acripet MF") [A3]. B3] and oleic acid monoglyceride [C3] were mixed in the composition ratio shown in Table 3, and the mixture was heated at 210°C in a 40φ extruder.
After kneading into pellets with 50z injection molding machine, 210
A 2 mm plate (110 x 110 mm) was prepared at °C.

Claims (1)

[Scope of Claims] 1. A copolymer [B] consisting of 100 parts by weight of methacrylic resin [A], 30-90% by weight of an alkali metal salt of methacrylic acid and/or acrylic acid, and 70-10% by weight of methyl methacrylate. ] 0.03 to 2.0 parts by weight and carbon number 8 to
A methacrylic resin composition having excellent antistatic properties and comprising 2 to 6 parts by weight of higher fatty acid monoglyceride [C] of No. 22.