JPS627224B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for preventing static electricity of methyl methacrylate resin moldings, and more specifically, by using a combination of a specific cationic surfactant and a specific ester compound when manufacturing methyl methacrylate resin moldings by the cell cast method. The present invention relates to a method for imparting good antistatic properties to the molded product without impairing its surface properties, colorability, transparency, and other properties. In general, synthetic polymer materials are highly electrostatically charged, and are prone to various processing troubles, electrostatic shock, dust adhesion, and other problems during the manufacturing process of molded products and the use stage of molded products. In methyl methacrylate resin molded products, which are characterized by transparency, dust adhesion to the surface significantly reduces the product value. The strength of the charging property of such methyl methacrylate resin material is similar to that of other hydrophobic synthetic polymer materials, and many attempts have been made to prevent various problems caused by its charging property, but among these, Industrially, the most advantageous way to impart antistatic properties to a hydrophobic polymer material is to add and mix an antistatic agent to the resin material. Therefore, as a conventional method for preventing static electricity in methyl methacrylate resin molded products molded by the cell cast method, various surfactants are added to and mixed with methyl methacrylate monomers or their low polymers, and the mixture is injected into cells and polymerized. is proposed.
Among the surfactants used for this purpose,
Some ionic surfactants such as anionic surfactants and cationic surfactants exhibit antistatic properties even when added in relatively small amounts, but they usually have poor compatibility with methyl methacrylate resins or polymerize. Since they have drawbacks such as a tendency to become colored inside, many of them seriously impede the properties of the molded product and cannot be put to practical use. In addition, compatibility with methyl methacrylate resins can be improved by introducing atomic groups such as ester bonds, ether bonds, and polyoxyalkylene groups into the molecules of these ionic surfactants; As in the case of polyoxyalkylene ether type nonionic surfactants, which are said to have extremely good antistatic properties, it is often necessary to add a fairly large amount to impart practical antistatic properties. However, deterioration of the mechanical properties of the molded product is unavoidable. On the other hand, other important technical problems have been pointed out in the production of methyl methacrylate resin molded products by the cell cast method. In other words, when a methyl methacrylate monomer or its low polymer is polymerized in a cell, the surface properties and workability of the molded product are greatly influenced by the degree of adhesion at the interface between the molded product and the cell. That's true. If the adhesion is too low, as polymerization progresses, the polymer, which has lost its fluidity, will locally peel off at the cell interface, and the polymerization will be completed, resulting in a completely smooth surface. This will not result in a good product. On the other hand, if the adhesion is too high, it becomes difficult to remove the molded product from the cell, and in extreme cases, the cell or the molded product may be damaged. However, although it is known that the degree of adhesion between cells and molded products is greatly affected by the antistatic agent used, its mechanism of action is unknown, and excessive No technology has yet been established to prevent adhesion or excessive peeling and to control the degree to an industrially practical level. Therefore, the actual situation is that in the production of methyl methacrylate resin molded products by the cell cast method,
There is a strong demand for the development of an excellent antistatic method that prevents excessive density and excessive peeling without reducing the workability when removing molded products from cells, and does not impair the properties of molded products. -ing In view of the above-mentioned circumstances, the inventors of the present invention have conducted extensive research on methods for preventing static electricity in methyl methacrylate resin moldings produced by the Cellcast method. When used in combination as an agent, excellent antistatic properties can be obtained with a relatively small amount of addition, and it can also prevent excessive adhesion between cells and molded products and peeling of cells that occurs during polymerization, improving transparency. The present inventors have found that this does not impair various properties such as coloring properties, surface properties, etc., and have completed the present invention. That is, the present invention uses a cationic surfactant in the following () and an ester compound in () in combination with the methyl methacrylate monomer or low polymer when producing a methyl methacrylate resin molded product by the cell cast method. This invention relates to a method for preventing electrification of methyl methacrylate resin molded articles. A quaternary ammonium salt type cationic surfactant represented by the following general formula. [However, R ₁ is an alkyl group, alkenyl group, alkylaryl group, or an alkylaryl group having 8 to 22 carbon atoms,
An alkyl group or alkenyl group containing an ether group, an ester group, or an amide group. _R2 is the same as _R1 , a lower alkyl group having 1 to 3 carbon atoms, or a hydroxyalkyl group having 2 to 3 carbon atoms. _R3 and _R4
is a lower alkyl group having 1 to 3 carbon atoms or a lower alkyl group having 2 to 3 carbon atoms
3 hydroxyalkyl group. X is a sulfonic acid ion or a phosphonate ion represented by the following general formula. RSO ₃ (R is an alkyl group having 1 to 3 carbon atoms)

[Formula] (However, R′ is hydrogen, methyl group, ethyl group, or vinyl group)

[Formula] (However, R″ is an alkyl group having 1 to 3 carbon atoms)] () Ester of aliphatic carboxylic acid having 8 to 22 carbon atoms and lower alcohol having 1 to 4 carbon atoms or a trivalent or higher aliphatic Partial ester with polyhydric alcohol. Specific examples of the cationic surfactant in the present invention include lauryltrimethylammonium monomethylphenylphosphonate, dilauryldimethylammonium monomethylphenylphosphonate, lauryltrimethylammonium methylsulfonate, and lauryldimethylhydroxyethylammonium. Examples include methyl sulfonate, stearyl trimethyl ammonium monomethyl phenyl phosphonate, lauroxyethyl triethylammonium methyl sulfonate, lauroyloxyethyl trimethyl ammonium ethyl sulfonate, lauroylaminopropyl trimethyl ammonium methyl phenyl phosphonate, etc. In the anion part of these cationic surfactants Certain sulfonate ions or phosphonate ions have particularly preferred molecular weights that are not too large, including, for example,
Examples include methylsulfonate anion and methylphenylphosphonate anion. Specific examples of aliphatic monocarboxylic acids having 8 to 22 carbon atoms constituting the ester compound used in combination with the cationic surfactant as exemplified above in the present invention include lauric acid, palmitic acid, stearic acid, oleic acid, There are acids, and mixed fatty acids obtained from various animal and vegetable oils and fats. Similarly, specific examples of lower alcohols having 1 to 4 carbon atoms constituting ester compounds include monohydric lower alcohols such as methanol, ethanol, propanol, butanol, and trihydric or higher aliphatic polyhydric alcohols. Specific examples include trihydric alcohols such as glycerin and trimethylolpropane, tetrahydric alcohols such as diglycerin and pentaerythritol, and hexahydric alcohols such as sorbitol and dipentaerythritol. Specific examples of ester compounds obtained from these fatty acids and alcohols include monovalent esters such as methyl oleate, methyl stearate, and butyl palmitate, glycerin monooleate, glycerin distearate, sorbitan monooleate, and sorbitan. Examples include polyhydric alcohol partial esters such as tristearate and glycerin monosafflower oil fatty acid ester. The main feature of the present invention is to use a specific cationic surfactant and a specific ester compound in combination, and the intended purpose can be achieved when both of them are as described above. For example, Monovalent esters with large molecular weights such as octyl stearate and oleyl laurate obtained from monohydric alcohols with a large number of carbon atoms, or complete esters of polyhydric alcohols such as glycerin triolate and pentaerythritol tetraoleate, etc.
It has poor compatibility with methyl methacrylate polymers, resulting in drawbacks such as promoting interfacial separation with cells during polymerization. When changing the ratio of the cationic surfactant and ester compound used together, generally speaking, the higher the ratio of the former, the lower the transparency and colorability of the molded product, and conversely, the higher the ratio of the latter, the lower the molding. The antistatic property of the product tends to decrease, and the phenomenon of interfacial peeling with the cell tends to occur. The preferred ratio of both is influenced by the type of compound used, but usually cationic surfactant/ester compound = 5/1.
~1/4 (weight ratio). Further, the total amount of both used is preferably in the range of 1.5 to 8 parts by weight, and 3 to 6 parts by weight based on 100 parts by weight of the methyl methacrylate resin.
A range of parts by weight is more preferred. Further, it is more effective when the material of the cell used in carrying out the present invention by the cell cast method is stainless steel. In the present invention, examples of the methyl methacrylate resin include a methyl methacrylate homopolymer and a copolymer containing methyl methacrylate as a main component with another copolymerizable monomer. Further, when carrying out the present invention, there is no problem in adding other additives, such as antioxidants, ultraviolet absorbers, lubricants, dyes and pigments, etc., as long as they do not impair the effects of the present invention. Next, in order to make the present invention more concrete, the present invention will be explained by giving examples. Example: To 100 parts by weight of methyl methacrylate monomer, 3 parts by weight of the cationic surfactant listed in Table 1 and 2 parts by weight of glycerin monooleate were added, and a thermometer, stirring device, and nitrogen gas introduction tube were attached. Uniformly dissolve in a flask and add 0.5 parts by weight of benzoyl peroxide as an opening agent at 60°C.
The mixture was stirred for 30 minutes in a hot water bath under a stream of nitrogen gas to obtain a syrup-like partial polymer. This is 2mm thick
The mixture was poured into a stainless steel cell set so that , this is Example 1
And so. In the same manner, using the additives listed in Table 1 or 2, Examples 2 to 5 and Comparative Examples 1 to 15 were used.
(Comparative Example 15 is a blank) sheet was obtained. The surface electrical resistance of these sheets was measured, and the transparency, colorability, and surface condition were evaluated. The results were as shown in Table 3 or Table 4. The measurement method or evaluation criteria are as follows. ...Surface electrical resistance: After the sheet was left in a constant temperature and humidity room at 20°C and 50% RH overnight, it was measured in the same atmosphere using a super insulation resistance meter (Model SM-5E) manufactured by Toa Denpa Kogyo. ...Transparency, colorability, surface condition: The sheet was visually observed and evaluated according to the following criteria. ...Transparency: 〇=No clouding observed △=Very slight clouding ×=Clearly clouding ...Colorability: 〇=No coloring △=Extremely Slight coloration × = Coloration clearly observed ...Surface condition: 〇 = No surface abnormality observed △ = Very slight surface abnormality (due to excessive adhesion or excessive peeling) observed ×=Surface abnormality is clearly recognized

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[Table] From the results in Table 3 relative to Table 4, it is clear that according to the present invention, which uses a specific cationic surfactant and a specific ester compound in combination, the amount added is smaller than when each is used alone. It is clear that the desired excellent antistatic properties can be imparted to the molded product, and that the molded product also has good results in other properties.

Claims (1)

[Claims] 1. When producing a methyl methacrylate resin molded product by the cell cast method, the following cationic surfactant in () and an ester compound in () are added to a methyl methacrylate monomer or low polymer. 1. A method for preventing static electricity of a methyl methacrylate resin molded product, characterized by containing a methyl methacrylate resin. () A quaternary ammonium salt type cationic surfactant represented by the following general formula. [However, R ₁ is an alkyl group, an alkenyl group, an alkylaryl group, or an alkyl group or an alkenyl group containing an ether group, an ester group, or an amide group, each having 8 to 22 carbon atoms.
_R2 is the same as _R1 , a lower alkyl group having 1 to 3 carbon atoms, or a hydroxyalkyl group having 2 to 3 carbon atoms. R ₃ and R ₄ are lower alkyl groups having 1 to 3 carbon atoms or hydroxyalkyl groups having 2 to 3 carbon atoms.
X is a sulfonic acid ion or a phosphonate ion represented by the following general formula. RSO ₃ (However, R is an alkyl group having 1 to 3 carbon atoms) [Formula] (However, R' is hydrogen, methyl group, ethyl group, or vinyl group) [Formula] (However, R″ is a carbon number 1 to 3 alkyl group)] () Ester of aliphatic carboxylic acid having 8 to 22 carbon atoms and lower alcohol having 1 to 4 carbon atoms or partial ester of trihydric or higher aliphatic polyhydric alcohol. 2 Cationic surfactant/ A method for preventing static electricity of a methyl methacrylate resin molded product according to claim 1, wherein the weight ratio of the ester compound is 5/1 to 1/4. 3. A patent in which the material of the cell used in the cell cast method is stainless steel. A method for preventing electrification of a methyl methacrylate resin molded article according to claim 1 or 2.