JPS6332091B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for curing and adhering an ultraviolet curable paint to an acrylic sheet, in which the ultraviolet curable paint is firmly adhered to the acrylic sheet by irradiation with ultraviolet rays. BACKGROUND ART Conventionally, methods for bonding objects to acrylic resin sheets or the like by chemical methods are broadly classified into solvent methods and polymerization methods. The former uses a highly volatile solvent that dissolves acrylic resin well to swell and dissolve the acrylic resin surface to be bonded.
This method is followed by pressure bonding and adhesion. On the other hand, the latter uses a syrup-like mixture of methyl methacrylate monomer and polymethyl methacrylate, adds a thermal polymerization initiator or a photopolymerization initiator, and pours the mixture between the bonding surfaces of the sheet and the object to be bonded. This is a method of bonding by heating or irradiating with ultraviolet rays. However, in the former solvent-based bonding method, adhesion occurs when the solvent evaporates after pressure bonding, so the bonding surface is relatively small or has a long and narrow shape where the solvent easily evaporates outside the system. However, if the bonding surface is close to a square and the bonding area is large, the solvent inside is difficult to volatilize and residual solvent often causes problems. Furthermore, in the latter adhesive method using the polymerization method, a thermal polymerization initiator or a photopolymerization initiator is already added to the adhesive liquid used, so there is a problem with pot life due to heat or light in the environment before use. On the other hand, regarding a method of curing and adhering an ultraviolet curable paint to a hard plastic sheet by irradiating it with ultraviolet rays, an attempt was made to improve the adhesion by examining the properties of a reactive diluent in the components of the ultraviolet curable paint. is also being carried out. However, in order to comprehensively satisfy the various other properties required for UV-curable paints, such as photocurability, pot life, surface hardness, heat resistance, and curing shrinkage rate, there are restrictions on the reactive diluents that should be used. Currently, the results are not necessarily satisfactory. Therefore, the acrylic sheet can be treated with a treatment liquid that can be commonly used for any type of ultraviolet curing paint, and there is no need to worry about solvent volatilization after adhesion, and there are no restrictions on pot life under any environment. There is a strong need for a method of increasing adhesion thereby. In order to eliminate the conventional drawbacks, the present invention provides a method for curing and adhering an ultraviolet curing paint to an acrylic sheet by irradiation with ultraviolet rays. - It is characterized by applying a thin layer of at least one of pyrrolidone, acrylic ester, or methacrylic ester, then applying an ultraviolet curing paint to the desired thickness on the treated surface, and then irradiating it with ultraviolet rays. The purpose is to satisfy photocurability, pot life, surface hardness, heat resistance, or curing shrinkage rate, and to improve adhesiveness. In the present invention, the treatment liquid applied to the acrylic sheet surface before applying the ultraviolet curable paint is preferably one that dissolves and swells the acrylic resin, such as N-vinyl-2-2-pyrrolidone, hydroxyethyl acrylate of acrylic acid ester, or tetrahydrochloride. Examples include furfuryl acrylate, benzyl methacrylate of methacrylic acid esters, glycidyl methacrylate, and ethylene glycol dimethacrylate, and these treatment liquids can be used as they are or as solutions that do not harm the sheet, such as alcohol. Hereinafter, the method of curing and adhering an ultraviolet curable paint to a methacrylate sheet of the present invention and its effects will be explained. [Example 1] 100% of the treatment solution shown in Table 1 was placed on an acrylic sheet.
% ethyl alcohol solution using a spin coater
Apply by spinning at 300 rpm and continue spinning for 1 minute. Afterwards, on the treated surface, an ultraviolet curing solution consisting of 100 parts by weight of 2,2-bis(4-acryloyloxydiethyleneoxyphenyl)propane (trade name, NK ester, A-BPE-4) and 2 parts by weight of benzoin isopropyl ether was applied. Apply the paint to a thickness of 100μm and irradiate it for 30 seconds with a 1KW high-pressure mercury lamp from a distance of 15cm. An adhesion test using a cross cut was conducted on each of the obtained samples, and the results shown in Table 2 were obtained.

[Table] As a comparative example, when no treatment liquid is used and
Even when using hydroxypropyl acrylate and carbitol acrylate, which hardly dissolve or swell the acrylic resin, as the treatment liquid,

[Table] The results are also shown. Similarly, as a comparative example, the reactive diluent of Samples No. 1 to No. 6 was added to 2,2-bis(4-acrylooxydiethyleneoxyphenyl)propane as the main component without using a treatment liquid. 20, 40, 60
We also evaluated the curing properties (time for the surface to become sticky) and adhesion when cured under the same conditions for samples to which benzoin isopropyl ether was added at a ratio of 2% by weight. It is shown in Table 3.

[Table] However, the cross-cut adhesion test means that the obtained ultraviolet-cured coating film is
100 mm square grids were made with a razor blade, adhesive tape was pasted on the surface of the coating film, and the tape was then rapidly peeled off to measure the number of grids to which the coating film was attached. In Table 2, the adhesion of 100/100 indicates that as a result of the adhesion test, 100 out of 100 grids adhered to the base material. As mentioned above, the adhesion to the acrylic sheet can be improved by adjusting the type and amount of reactive diluent added to the base resin of the UV-curable paint.
On the other hand, a decrease in curability was observed, and a decrease in surface smoothness was observed due to a decrease in surface hardness and an increase in curing shrinkage. On the other hand, it can be seen that the method of the present invention has the effect of adhering the ultraviolet curable paint to the acrylic sheet with strong adhesion by irradiation with ultraviolet rays.

Claims (1)

[Claims] 1. In a method of curing and adhering an ultraviolet curing paint to an acrylic sheet by irradiation with ultraviolet rays, N-vinyl-2-pyrrolidone, which dissolves and swells the acrylic sheet on the adhesive surface of the acrylic sheet, or Apply a thin layer of at least one of acrylic ester or methacrylic ester, then apply UV-curable paint to the desired thickness on the treated surface, and then cure the UV-curable paint by irradiating it with ultraviolet light. A method for curing and adhering UV-curable paint to acrylic sheets. 2. Claim 1, wherein the acrylic ester or methacrylic ester is at least one of hydroxyethyl acrylate or tetrahydrofurfuryl acrylate, and the latter one of benzyl methacrylate, glycidyl methacrylate, or ethylene glycol dimethacrylate. Method for curing and adhering an ultraviolet curing paint to an acrylic sheet as described in Section 1.