JPH0671577B2 - How to cure and cure UV-curable paint - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a coating and curing method for an ultraviolet curable coating composition which is instantly cured by being irradiated with ultraviolet rays.

Conventional techniques As a coating method for UV-curable coatings, usual methods such as roll coater, bar coater and spray can be used, but in order to form a desired smooth surface, the above coating is applied between the coating machine and the UV irradiation lamp. It was necessary to provide a long section for leveling the surface or heat to promote leveling.

Japanese Patent Application Laid-Open No. 47-30730 proposes a method in which after applying a UV-curable coating material, a transparent film is attached to the application surface with a pressing roll, and then ultraviolet rays are radiated through this film. Polyethylene terephthalate film, which is widely used for the above, partially absorbs ultraviolet rays having a wavelength effective for curing the ultraviolet curable coating material, so that the efficiency is reduced so much that the desired sufficient coating film hardness cannot be obtained or the hardness is not sufficient. Since it is sufficient, there is a drawback that it is difficult to remove dust and dirt attached during storage or handling.

Problems to be Solved by the Invention Therefore, an ultraviolet curable coating material can be uniformly applied onto an object to be coated, and the coating surface can be formed into a desired smooth surface, and a sufficient coating film hardness can be obtained. There is a demand for a method for coating and curing an ultraviolet curable coating material that can easily remove dust deposits, and it is an object of the present invention to meet such a problem.

Means for Solving the Problems According to the present invention, the above-mentioned object is to apply an ultraviolet-curable coating material to the surface of an object to be coated, and tightly press-bond a transparent film material to the surface of an uncured coating film to pass through the film material. This can be achieved by a method of coating and curing an ultraviolet-curable coating material, which comprises irradiating ultraviolet rays, then peeling off the film-like material, and then directly irradiating the surface of the coating film with ultraviolet rays again.

That is, in the coating curing method of the present invention, an ultraviolet curable coating material is applied to an object to be coated directly or through an undercoat coating film, and then a transparent film material (hereinafter referred to as "film") is superposed on the coating surface of the ultraviolet curable coating material. In such a state, an appropriate means such as, for example, conveying and supplying an object to be coated on which the coating film and the film are laminated between a pair of upper and lower pressing rolls, and feeding the film from the pressing roll to perform tight compression bonding of the film on the coating surface. A two-step irradiation curing method comprising a first step of irradiating the coating surface through the film and then a second step of separating the film from the coating surface and then directly irradiating the coating surface with ultraviolet light. is there.

In this way, curing is not completed in the first step of irradiating ultraviolet rays in a tightly compressed state on the coated surface of the ultraviolet curable coating material, and after the transparent film is separated from the coating surface, the second step of irradiating ultraviolet rays is performed. By providing and completing curing, "vertical streaks" etc. that entered the surface of the coating film in the first step can be smoothed in the second step, so that a defective finish on the surface is prevented from occurring and an ultraviolet curable coating The appearance of the coating film can be improved. Also, in the irradiation of the first step, there is no curing delay due to the polymerization inhibition effect of oxygen in the air because irradiation is carried out through a transparent film, and after the curing reaction is effectively advanced, the film is removed and irradiation is performed in the second step. Therefore, after all, a coating film having a desired high sharpness, a high surface hardness, a scratch resistance, and easy removal of attached dust and dust can be obtained.

In this connection, in order to secure the high definition of the coating film, it is necessary to use the film itself having a high smoothness. On the contrary, when it is necessary to make the surface of the coating film matt depending on the purpose, use a matte film with a large surface roughness and use the smoothness (roughness) of the film surface It is also possible to obtain a desired matte coating surface finish by adjusting the irradiation amount in the first and second steps.

Further, when the method according to the present invention is not used, that is, as compared with the conventional method such as the method in which the film is not attached from the beginning and the irradiation is completed with the transparent film attached, less irradiation is performed. It is advantageous because the curing can be completed in an amount.

Hereinafter, the present invention will be described with reference to examples.

Example 1 A surface-treated zinc iron plate having a thickness of 0.4 mm was added to 100 parts by weight of Superlac E-50 White (a thermosetting acrylic resin paint manufactured by Nippon Paint Co., Ltd.), and Cymail 325 (Mitsui East). Mix 5 parts by weight of pressure chemical Co., Ltd. (melamine resin) and stir until uniform until the dry coating thickness is 20μ. 6 to reach 220 ℃ in 60 seconds 6
Heat dried for 0 seconds. Epoxy ester 1600A (Kyoeisha Yushi Co., Ltd.) was formed on the base coating film thus formed.
65 parts of 1,6-hexanediol diglycidyl ether diacrylate), Viscoat 700 (Osaka Organic Co., Ltd.)
20 parts of diacrylate of ethylene oxide 4 mol adduct of bisphenol A), 15 parts of neopentyl glycol monobenzoate monoacrylate, 3 parts of benzyl dimethyl ketal to make a film thickness of 15 μ with a natural roll coaster. Applied.

Next, a 75 μm thick polyethylene terephthalate film was immediately laminated, and this was tightly pressed through the pressure rolls, and then the high voltage mercury lamp HI-40N (80 W / cm) manufactured by Nippon Battery Co., Ltd.
Place one lamp at the bottom of the lamp at a height of 80 mm above the conveyor surface, with the lamp length direction perpendicular to the conveyor traveling direction, irradiate at a conveyor speed of 10 m / min, peel off the polyethylene terephthalate film, and use the same high-pressure mercury lamp again. ,
Irradiation was performed at a conveyor speed of 10 m / min under the same conditions. The obtained coating film performance is shown in Table 1.

Comparative Example 1 A zinc iron plate was coated with an undercoat paint and an ultraviolet curable paint composition in exactly the same manner as in Example 1, and a polyethylene terephthalate film was adhered to the coated object at a conveyor speed of 5 m.
After irradiation at / min, the polyethylene terephthalate film is peeled off to obtain a cured coating film. In this case, the irradiation amount of ultraviolet rays is the same as that in the first embodiment. The obtained coating film performance is shown in Table 1.

Comparative Example 2 A zinc iron plate was coated with an undercoat paint and an ultraviolet curable paint composition in exactly the same manner as in Example 1, and then the object to be coated was irradiated with a conveyor speed of 5 m / min without curing the polyethylene terephthalate film, and cured. Obtain a coating film. In this case, the irradiation amount of ultraviolet rays is the same as that in the first embodiment. The obtained coating film performance is shown in Table 1.

Evaluation method Pencil hardness: Hardness with scratches by Mitsubishi Uni-Pencil (JIS KY 5400) Image clarity: NSIC and NSIC * values were measured using an image clarity measuring instrument NSIC meter (manufactured by Suga Test Instruments Co., Ltd.). Both values are up to 100,
The higher the value, the higher the clarity.

Surface condition: Observing and evaluating the adhesion state of dust and lumps during curing of coating 〇… No dust and lumps ×… ² to 3 pieces per 1 m ² After coating curing Ease of removal of dust and dust attached to the stock: Coating curing After leaving the board in a room where people come and go for a week, lightly wipe off dust and dirt adhering to it.

Evaluation 〇… easily wiped △… somewhat difficult to wipe ×… difficult to wipe

Claims (1)

[Claims] 1. A UV-curable coating material is applied to the surface of an object to be coated, a transparent film-like material is tightly pressure-bonded to the surface of an uncured coating film, and ultraviolet rays are radiated through the film-like material before complete curing. A method for coating and curing an ultraviolet-curable coating material, which comprises peeling the above film-like material and irradiating the coating film surface directly with ultraviolet rays.