JPS6247903B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a coating composition for coating plastic moldings that has excellent surface hardness, abrasion resistance, flexibility, transparency, antistatic properties, dyeability, and heat resistance. . [Conventional technology] Plastic molded products are used in large quantities due to their advantages such as light weight, easy workability, and impact resistance. However, on the other hand, they are insufficiently hard, easily scratched, easily immersed in solvents, and susceptible to electrostatic charge. It has drawbacks such as adsorption of dust and insufficient heat resistance, and is unsatisfactory in practical terms compared to inorganic glass when applied to eyeglass lenses, window glass sheets, etc. Although many proposals have been made regarding coating methods with high hardness materials as means for improving these drawbacks, the reality is that no method has been found that is fully satisfactory. For example, coating compositions made from a combination of hydrolyzed condensates of tetraalkoxysilicon such as butyl silicate, and trifunctional silanes such as methyltrimethoxysilane and vinyltrialkoxysilane have already been commercialized and are used in sunglass lenses, etc. Although it has a high surface hardness, it has insufficient flexibility and has the disadvantage of cracking on the surface when heated to over 80℃ under stress or exposed outdoors, so it is not suitable for severe applications such as window materials. It was inappropriate. Also, JP-A-50-40674, JP-A-50-69184
No. 50-96670 discloses a high-hardness paint obtained by mixing an epoxy group-containing alkoxysilane with a Lewis acid or its complex, or Brønsted acid, but these paints have a short pot life. It has a fatal drawback in that it takes a long time to cure, so it cannot be said to be practical. The present inventors previously proposed a coating composition consisting of a hydrolyzate of an epoxy group-containing alkyltrialkoxysilane and a zinc borofluoride, tin borofluoride, or boron trifluoride/amine complex (Japanese Patent Application Laid-Open No. 1983-1972-1). 117529), but this composition has drawbacks such as insufficient water resistance of the coating film, resulting in a decrease in hardness when immersed in hot water, and yellowing of the coating film when exposed to high temperatures for a long period of time. . On the other hand, in recent years CR-39 has been used as a plastic molded product.
(Diethylene glycol bisallyl carbonate polymer) has been developed and is widely used in eyeglass lenses because of its better surface hardness than thermoplastic resins, but its scratch resistance is insufficient and it easily breaks during machining. The reality is that there are drawbacks such as these, and improvements are desired. [Problems to be Solved by the Invention] As a result of intensive research into the improvement of these problems, the present inventors have found that the resin composition of the present invention described in detail below is extremely useful for solving these problems all at once. They discovered this and completed the present invention. In other words, the present invention has high elongation, extremely low risk of cracking on the coating surface even if the base material bends, excellent hot water resistance, light resistance, and weather resistance, excellent antistatic properties, antifouling effect, and dispersion. To provide a technology for producing a coating film that can be dyed with a dye, has a high surface reflectance, and has good adhesion to metal vapor deposited films. In particular, we provide a unique technology that enables dyeing with disperse dyes and gives optical products such as lenses a high-class look such as fashionability. [Means for solving the problems] The present invention consists of the following configuration. "A curable resin composition comprising a hydrolyzate of a silicon compound represented by the following general formula (), an epoxy curing agent, and an epoxy resin compound, and characterized in that it is a coating material for coating plastic molded articles. (However, m = 2 to 4, R ¹ is alkyl, alkoxyalkyl, or acyl, and m R ¹ O may be the same or different. R ² is C ₁ to C ₆ alkyl,
alkenyl or aryl, (4-m) R ²
may be the same or different types. )" In the present invention, the combination of the epoxy resin compound and the epoxy curing agent has a conventionally well-known composition. However, the technical point and novelty of the present invention is that a hydrolyzate of the silicon compound represented by the above general formula () is added to the epoxy resin compound and epoxy curing agent. This results in good adhesion to the plastic molded article (base material), and the objectives of the present invention, such as improved surface hardness, hot water resistance, scratch resistance, ease of machining, and dyeability, can be achieved for the first time. Ta. Examples of the hydrolyzate of the silicon compound represented by the above general formula () of the present invention include methyl silicate,
Ethyl silicate, isopropyl silicate, n
-propyl silicate, n-butyl silicate,
Hydrolysates of tetraalkoxy silicon such as sec-butyl silicate and tert-butyl silicate, or methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane , phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and other alkyltrialkoxysilanes, alkyltriacyloxysilanes, alkenyltrialkoxysilanes, alkenyltriacyloxysilanes, and aryltrialkoxysilanes. , or hydrolyzates of dialkyl, diaryl, or alkylaryl dialkoxysilanes such as dimethyldimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane. The most suitable hydrolyzate is used depending on the purpose and application, but from the viewpoint of the balance between surface hardness and flexibility, as well as weather resistance, methyltrisilanol or its partial condensate is preferred. Most preferably used. Further, the above-described silanol group-containing compounds are preferably used not only as a single type but also as a mixture of two or more types, and further as a copartial condensate. Hydrolyzates of these silicon compounds are produced by hydrolysis with pure water or an acidic aqueous solution such as hydrochloric acid or sulfuric acid. This is usually carried out by adding an acidic aqueous solution to the silicon compound at once. Furthermore, the hydrolysis rate can be easily controlled by adjusting the addition rate or external temperature depending on the purpose. During hydrolysis, alcohol, alkoxy alcohol, organic carboxylic acids such as acetic acid, etc. are produced, so hydrolysis can be carried out without a solvent. Furthermore, the silicon compound can be mixed with a suitable solvent and then hydrolyzed. Depending on the purpose, it is also possible to use the product after hydrolyzing it without a solvent and removing an appropriate amount of the resulting alcohol, alkoxy alcohol, or organic carboxylic acid such as acetic acid, and water under heating and/or reduced pressure. It is also possible to substantially replace the solvent by subsequently adding a suitable solvent. As the solvent, various alcohols, esters, ethers, ketones, halogenated hydrocarbons, and aromatic solvents such as toluene can be used depending on the purpose, and mixed solvents can also be used if necessary. The epoxy compounds of the present invention are those that are widely used in paints, castings, etc., such as polyolefin-based epoxy resins synthesized by peroxidation methods, cyclopentadiene oxide, cyclohexene oxide, or hexahydrophthalic acid and epichlorohydrin. Alicyclic epoxy resins such as the resulting polyglycidyl esters, polyhydric phenols such as bisphenol A, catechol, and resorcinol, or (poly)ethylene glycols,
Polyglycidyl ethers obtained from epichlorohydrin and polyhydric alcohols such as (poly)propylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerol, and sorbitol; polyglycidyl ethers obtained from epoxidized vegetable oils, novolac type phenolic resins, and epichlorohydrin. Examples include epoxy novolac, epoxy resins obtained from phenolphthalein and epichlorohydrin, and copolymers of glycidyl methacrylate and acrylic monomers such as methyl methacrylate, or styrene. As the epoxy curing agent of the present invention, any known compound used in epoxy resins can be used, but aluminum compounds represented by the following general formula are particularly preferred. Al・X _o Y _3-o (X is -OR (R is lower alkyl) or halogen, and -OR is particularly preferable. n is 0, 1 or 2.) Among such aluminum compounds, acetylacetone aluminum salt, aluminum-dialkoxide-monoalkyl acetoacetate and the like are preferably used. Specific examples of aluminum dialkoxide monoalkyl acetoacetate are as follows. Aluminum di-n-butoxide mono-ethyl acetoacetate, aluminum di-n-
Butoxide mono-methyl acetoacetate, aluminum di-tert-butoxide mono-ethyl acetoacetate, aluminum di-sec-
Butoxide mono-methyl acetoacetate, aluminum di-sec-butoxide mono-ethyl acetoacetate, aluminum di-iso-
propoxide-mono-methylacetoacetate,
It is selected from the group such as aluminum di-ethoxide mono-methylacetoacetate and aluminum di-methoxide mono-methylacetoacetate. It is also possible to use a mixture of two or more of these. A preferred method of using the composition of the present invention is when it is used as a coating material,
At that time, it improves the flow of paint during application,
It is also possible to use surfactants for the purpose of improving the smoothness of the coating film and lowering the coefficient of friction on the coating surface, and book or graft copolymers of dimethylsiloxane and alkylene oxide are particularly effective. be. It is also easy to disperse dyes and pigments and fillers, dissolve organic polymers, color the coating, and improve its practicality as a coating agent by improving its applicability, adhesion to substrates, and physical properties. possible. Materials to be coated include polymethyl methacrylate, acrylonitrile-styrene copolymer, polycarbonate, cellulose acetate,
Plastic molded products include cross-linked polymethyl methacrylate, polyvinyl chloride, epoxy resin, and CR-39 (diethylene glycol bisallyl carbonate polymer). As a coating means, commonly used coating methods such as brush coating, dip coating, roll coating, spray coating, and flow coating can be easily used. It is also possible to apply the present composition to a mold and then cast-polymerize the base material raw material, or to complete heat curing by bringing the plastic base material coated with the present composition into close contact with the mold. Furthermore, it is easily possible to add an ultraviolet absorber for the purpose of improving weather resistance, and an antioxidant to improve heat deterioration resistance. The amount of the epoxy curing agent added in the present invention is 0.0001 to 1 part by weight of the silicon compound hydrolyzate.
A suitable amount is 0.5 part by weight, particularly preferably 0.0005 to 0.1 part by weight; less than this will result in insufficient curing, while more than this will cause defects such as decreased transparency of the coating film or resin. Further, the amount of the epoxy resin compound of the present invention added is not particularly limited, but from the viewpoint of surface hardness and wear resistance, 250 parts by weight per 100 parts by weight of the silicon compound hydrolyzate.
A suitable amount is not more than 200 parts by weight, particularly preferably not more than 200 parts by weight. That is, if the amount exceeds this value, it becomes difficult to obtain sufficient scratch resistance. Curing of the composition of the present invention is mainly carried out by heat treatment, but the heating temperature can be used over a much wider range than in the case of conventional thermosetting resin compositions, and sufficiently good results have been obtained at 50 to 250°C. It will be done.
In addition, when coating a thermoplastic resin with a relatively low heat distortion temperature and then heating it to a high temperature, it is possible to prevent distortion and shorten the curing time by using an appropriate support such as a mold. be. The present invention was originally filed as Japanese Patent Application No. 51-29206 (Japanese Unexamined Patent Publication No. 52-112698). That is, the invention was disclosed in claim number (1) (A), Example 17, Comparative Examples 7, 8, and others of the patent application. The parent application was limited to silicon compounds containing epoxy groups, whereas the present invention is different in that the silicon compounds do not contain epoxy groups. [Examples] In order to clarify the gist of the present invention, Examples are given below, but the present invention is not limited to these Examples. Note that parts and percentages in the examples are based on weight. Example 1, Comparative Examples 1, 2, 3 (1) Preparation of methyltrimethoxysilane hydrolyzate 136 parts of methyltrimethoxysilane was charged into a reactor equipped with a rotor, and stirred vigorously using a magnetic stirrer. Meanwhile, 54 parts of a 0.01N aqueous hydrochloric acid solution was added dropwise while maintaining the liquid temperature at 20°C, and after the addition was completed, stirring was continued for an additional 30 minutes.
It was prepared by adding 65 parts of ethylene chlorohydrin/isopropyl alcohol=1/2 (weight ratio) and 8 parts of acetic acid (hereinafter abbreviated as H-MTM). (2) Preparation and coating of paint The above-mentioned H-MTM, one with added “Denacol” EX-314 as an epoxy resin (Example 1), one without (Comparative Example 1), and the epoxy resin agent. Acetylacetone aluminum salt was used in each case. Note that both Comparative Examples 2 and 3 are systems in which no epoxy curing agent is added. The amounts added of each are shown in Table 1. A 2 mm thick polymethyl methacrylate cast plate (trade name "Sumibex", manufactured by Sumitomo Chemical Co., Ltd.) was used as the object to be coated, and the dipping method was used (pulling speed 20 cm/min).
The film was applied with a hot air dryer at 130°C for 2 hours. A performance test of the cured product was conducted in accordance with the following. The test results are shown in Table 1. (a) Abrasion resistance test Rub with steel wool #0000 to check the resistance to scratches. Judgment was made as follows. A...It won't get scratched even if it is rubbed strongly. B... If you rub it quite strongly, it will get a little scratched. C...Even weak friction can cause damage. Note that the polymethyl methacrylate casting plate that was not coated at all was C. (b) Appearance Transparency and other defects in the coating film were examined with the naked eye. (c) Adhesion test Strongly adhere cellophane adhesive tape (trade name "Cellotape" manufactured by Nichiban Co., Ltd.) to the coating surface, and
The film was peeled off sharply in the direction of 3 degrees to check for peeling of the paint film. (d) Water resistance test After being immersed in hot water at 80°C for 30 minutes, the abrasion resistance test shown in (a) was conducted. (e) Dyeing property test The dyeing property was visually judged by immersing it in a disperse dye dye bath consisting of a mixture of three colors, blue, red, and yellow, at 90°C for 30 minutes. The ranking of the results is as follows. A...Dark brown color. B...Pale brown color. C...It doesn't stain. Example 2 In Example 1, the epoxy hardener acetylacetone aluminum salt was replaced with another well-known epoxy hardener, trimellitic anhydride (5 parts)/dicyandiamide (5 parts). In addition, as a solvent, ethylene chlorohydrin/
N-propyl alcohol was used instead of isopropyl alcohol. All other conditions were the same as in Example 1. As shown in Table 1, the results show wear resistance, appearance,
Adhesion, water resistance, and dyeability were all the same as in Example 1, and were excellent. Example 3 In Example 1, the epoxy curing agent acetylacetone aluminum salt is replaced with another known epoxy curing agent. A 72.5% by weight solution of trimellitic anhydride (5 parts)/di-n-butoxytitanium bisacetylacetonate in n-butanol (5 parts) was used. Furthermore, as a solvent, n-propyl alcohol was used instead of ethylene chlorohydrin/isopropyl alcohol. All other conditions were the same as in Example 1. As shown in Table 1, the results show wear resistance, appearance,
Adhesion, water resistance, and dyeability were all the same as in Example 1, and were excellent.

[Table] [Effects of the Invention] The coating film or molded product obtained by the present invention as described above is transparent and has excellent hardness, especially scratch resistance, and is hardly scratched even when strongly rubbed with a hard material such as steel wool. There is no deterioration in appearance due to scratches during use, which was a problem with plastic molded products, and since it can be dyed with disperse dyes, it can be applied to the production of products with extremely high commercial value. be. Furthermore, in addition to the top scratch resistance, the coating film or cast product according to the present invention has excellent scratch resistance and is compatible with conventional polysiloxane coating compositions or
Compared to thermosetting resin molded products such as CR-39, it (1) has greater elongation, and there is significantly less risk of cracking on the coating surface even if the base material bends. (2) Excellent hot water resistance, porosity resistance, and weather resistance. (3) Excellent antistatic properties and stain prevention effect. (4) Can be dyed with disperse dyes. (5) Good adhesion of metal vapor deposited films. This has a special effect.

Claims (1)

[Scope of Claims] 1. A curing agent comprising a hydrolyzate of a silicon compound represented by the following general formula (), an epoxy curing agent, and an epoxy resin compound, and is a coating material for coating plastic molded articles. resin composition. (However, m = 2 to 4, R ¹ is alkyl, alkoxyalkyl, or acyl, and m R ¹ O may be the same or different. R ² is C ₁ to C ₆ alkyl,
alkenyl or aryl, (4-m) R ²
may be the same or different types. ) 2. The curable resin composition according to claim 4, wherein the epoxy curing agent is an aluminum compound represented by the following general formula (). Al・X _o Y _3-o () (X is -OR (R is lower alkyl) or halogen, Y is a β-diketone compound or β-
Indicates a ligand derived from a ketoester compound,
n is 0, 1 or 2. ) 3. The curable resin composition according to claim 4, wherein the hydrolyzate of the silicon compound contains methyltrisilanol or a partial condensate thereof.