JPS6144112B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating epoxy composition suitable for application to plastic molded articles. Epoxy resin paints are known, but conventional ones require heat treatment at high temperatures to cure the paint, so if the base material to be coated is plastic, the base material cannot withstand the heat. Furthermore, those that can be cured at low temperatures require a long time to cure, resulting in low productivity and impractical use. Therefore, the present inventors have focused on a paint that can be cured at low temperatures and in a short time, which is made of a mixture of unpolymerized epoxy and an aryldiazonium compound, and which polymerizes and hardens by irradiation with ultraviolet light. However, when the above-mentioned UV-curable epoxy paint is applied to, for example, a plastic sheet and vacuum-formed, problems arise such as cracks in the epoxy paint film as the sheet deforms, and in extreme cases, the paint film peels off. Ta. The present invention is a coating composition that solves these problems and also provides various desirable properties. This is an epoxy composition for painting in which 0.5 to 10 parts by weight of a fatty acid ester of a polyhydric alcohol is added to a mixture consisting of the following. The present invention will be explained in detail below. The coating composition of the present invention is suitable for coating the surface of plastic molded articles, such as polyvinyl chloride, copolymer resins of vinyl chloride and ethylene, vinyl acetate, etc., polyethylene, polypropylene, ABS, polyethylene terephthalate, etc. It is used to improve the weather resistance, chemical resistance, surface hardness, slipperiness, etc. of the molded product by applying it to the surface of the molded product. The type and shape of the molded product to which the coating composition of the present invention is applied is not particularly limited, but it is most effective when applied to sheets and plates that are often subjected to post-processing such as vacuum forming, press working, and bending. be effective. Each component of the composition of the present invention will be explained below. In addition, "part" expressing the addition amount below means "part by weight." The epoxy monomer that is the main component of the composition of the present invention is represented by the following structural formula and has an epoxy ring. (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are alkyl, aryl, alkoxy, alkenyl and hydrogen.) Examples of the above monomers include ethylene oxide and homologs thereof; glycidic acid and glycidyl esters: glycidyl meth Acrylates, acrylates and crotonates; and allyl glycidyl ether. Further, the epoxy may be a low polymer containing the above-mentioned monomers and may be post-curable, and it is particularly desirable that the epoxy is liquid at room temperature. In the following explanation, the term epoxy monomer includes its low polymer. Next, the photosensitive aryldiazonium compound used in the present invention is represented by the following structural formula. (In the formula, MX _o+n is hexachlorostannate,
is a halogen-containing complex anion selected from tetrachloroferate, hexafluoroarsenate, hexachloroantimonate V, hexafluorantimonate and bismuth chloride; Y is nitro, halogen, N-morpholino, alkyl, alkoxy, aryl, amino,
selected from the group consisting of arylamino, alkylamino and arylmercapto groups. Furthermore, m corresponds to the number of halogen atoms in the Lewis acid produced upon irradiation with ultraviolet rays. That is, it corresponds to the charge of the complex cation. ) When exposed to ultraviolet light, the aryldiazonium compounds form Lewis acids of the general formula _MXo (i.e., _PF5 , _Fecl3 , _AsF5 , _SbF5 , _Sncl4 and _Bicl3) .
etc.), and the Lewis acid initiates the polymerization of the epoxy monomer. Examples of the aryldiazonium compound include diazonium hexafluorophosphate such as P-methoxybenzenediazonium hexafluorophosphate, O-nitrobenzenediazonium hexafluorophosphate, 2,5-dichlorobenzenediazonium hexafluorophosphate, and P-N- Examples include N-morpholino complexes such as morpholinophenyldiazonium hexafluorophosphate, 2,5-dimethoxy-4-N-morpholinobenzenediasonium hexafluorophosphate, and P-N-morpholinophenyldiazonium hexafluoroantimonate. . The aryldiazonium compound is used in an amount of about 1 to 10 parts per 100 parts of the epoxy monomer. The present invention further adds a fatty acid ester of a polyhydric alcohol to the epoxy monomer and the aryl diazonium compound, and the addition prevents cracking of the coating film during the post-processing and improves the coating composition. It improves coating properties, antistatic properties, slip properties, etc. The fatty acid ester of polyhydric alcohol in the present invention refers to a monoester of ethylene glycol or glycerin and a fatty acid having 12 to 22 carbon atoms, such as ethylene glycol monostearate, glycerin monostearate, glycerin monostearate, etc. These include oleate, glycerin monoricinolate, etc. These monoesters have good compatibility with epoxy monomers and the like, and exhibit the various effects mentioned above even when added in a relatively small amount. The amount added is per 100 parts of epoxy monomer.
The range of 0.5 to 10 parts is preferable; if it is less than 0.5 parts, the addition effect will not appear, and if it is more than 10 parts, the coating film will become sticky, and the inherent properties of epoxy such as chemical resistance will deteriorate, and furthermore, the subsequent This is not preferable because the time required for the coating film curing treatment becomes longer. A particularly preferable addition amount is 1 to 5 parts; within this range, the desired effects such as crack prevention during post-processing can be sufficiently achieved in practice, and the addition can reduce the physical properties of the coating film. This is preferable since there are no adverse effects. To apply the above-described coating composition to the surface of a molded article, a conventional bar coater, roll coater, etc. may be used, and depending on the case, a spray method, a dipping method, etc. may also be used. The coating thickness depends on the application, but is usually in the range of about 1 to 30 microns. After application, let it stand for several seconds to several minutes, and then irradiate the coating film for about 0.5 seconds to 1 minute with an ultraviolet irradiation device (e.g., mercury lamp, xenon lamp, tungsten filament lamp, etc.).
The photosensitive aryldiazonium compound decomposes to produce a Lewis acid, which serves as a polymerization initiation catalyst to polymerize and harden the epoxy monomer. In this case, since the fatty acid ester of the polyhydric alcohol is nonionic, it does not interfere with the polymerization and curing reactions. In addition, when applying the composition of the present invention to the surface of a molded product, in order to improve the adhesion between the molded product and the coating film, there are methods of preheating the surface of the molded product or the coating composition to a temperature below the heat-resistant temperature of the plastic molded product, It is also possible to adopt a method in which the surface of the molded product is dissolved or swollen in advance with an appropriate solvent to improve the adhesion of the coating film, and even in these cases, the fatty acid ester of the polyhydric alcohol does not pose any problem. It won't happen. Further, in order to adjust the viscosity of the composition, an inert solvent such as acetone, acetonitrile, toluene, xylene, etc. can also be used. The composition of the present invention provides good adhesion when applied to a molded article made of vinyl chloride resin, and is therefore particularly suitable. The present invention will be explained below with reference to Examples. Example 1 An extruded sheet with a thickness of 2 mm was molded from the following formulation. Vinyl chloride homopolymer (average degree of polymerization 800)
...100 parts Dibutyltin malate ester ...3 parts Lubricant (WaxOP) ...0.3 parts On one side of the sheet, 100 parts of epoxy monomer (Ultraset ADX-800 manufactured by Asahi Denka Co., Ltd.), p-
A coating liquid consisting of 3 parts of methoxybenzenediazonium hexafluorophosphate (PS-33 manufactured by Asahi Denka Co., Ltd.) and the types and amounts of additives shown in Table 1 was applied to a thickness of 10 μm using a roll coater at a sheet temperature of 80°C. It was applied to. Then, after being allowed to stand for 1 minute, the coating film was irradiated with ultraviolet rays for 5 seconds using a high-pressure mercury lamp to cure the coating film, thereby obtaining a coating sample. Table 1 shows the results of evaluating the properties of the coated samples using methods 1) to 5) below. 1 Surface smoothness Measure the surface roughness of the coated surface using a stylus surface roughness meter (Talysurf type 4 manufactured by Taylor Hobson).
Displayed as a 10-point average roughness according to JISB0601-1976. It can be said that the smaller this value is, the better the coating property is. 2 Slip property Layer two coated samples so that their coated surfaces are in contact with each other, and measure with a friction angle measuring device. Those that slip at an angle of inclination of less than 25 degrees are marked 0, and those that slip at an angle of 25 degrees or more are marked with an X. did. 3 Tensile strength, elongation, flexural modulus Based on JIS K 6745. 4 Vacuum formability At molding temperature of 130℃, diameter 100mm, depth 10
mm cup-shaped containers were vacuum formed and the presence or absence of cracks in the coating film was examined. 5 Charging property According to JIS L 1018, a cotton cloth was brought into contact with the coated surface of the coated sample under a load of 400 grams, and the frictional charging voltage was measured after rubbing for 1 minute at a drum rotation speed of 450 times/min.

【table】

[Table] As is clear from the results shown in Table 1, the products coated with the composition of the present invention to which ethylene glycol monostearate or glycerin monooleate was added (Experiment Nos. 5 and 6) were superior to the compositions shown for comparison. Compared to the coated products (Experiments Nos. 2 to 4), the coating properties, slip properties, processability such as vacuum forming, antistatic properties, etc. are all excellent. Example 2 Coated samples were prepared and evaluated in the same manner as in Example 1, except that ethylene glycol monostearate was added as an additive to the coating liquid in the amounts shown in Table 2. The results are shown in Table-2. The compositions of Experiment Nos. 7 to 10 could be cured in about 0.5 seconds to the extent that no fingerprints were left on them when pressed with a finger, but the composition of Experiment No. 11 took about 2 seconds to cure. , it was unsuitable for high-speed production.

【table】

Claims (1)

[Claims] 1 Epoxy monomer and/or its low polymer
An epoxy composition for coating, in which 0.5 to 10 parts by weight of a fatty acid ester of a polyhydric alcohol is added to a mixture consisting of 100 parts by weight and a photosensitive aryldiazonium compound.