JP2002177880A - Method for forming cured coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cured coating film forming method, by which it can be simply judged whether light irradiation is performed, that is, whether coating film is cured, in a short time, and by which a photo-fading colorant can be substantially decolored in a shorter time in comparison with conventional methods to return whole of the coating film to the original color of a surface-to- be-coated, and to provide a cured coating film forming method, by which a uniform primer layer can be formed without causing a non-coating part and coating irregularity of the primer. SOLUTION: A primer that contains a photo-fading colorant and a photo- initiator as essential components is applied to a surface-to-be-coated to form a primer layer, and then a photopolymerizable coating agent that contains a photopolymerizable resin and a photo-initiator as essential components is applied to the primer layer, which is irradiated with light to cure the coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photobleachable colorant which can be easily judged by visually observing a change in the color of the photobleachable colorant, and a photobleachable colorant upon irradiation with light. A method for forming a cured coating film, in which the color of the coating film is substantially transparent and the color of the coating film is substantially transparent so that the original color of the surface to be coated can be seen when viewed from above the coating film. About. Furthermore, the present invention relates to a method for forming a cured coating film capable of easily forming a substantially uniform primer layer on the entire surface to be coated, while easily checking visually the remaining coating and uneven coating of the primer layer.

[0002]

2. Description of the Related Art In general, curing of a photopolymerizable resin is completed in a short time by irradiating a specific light. When a composition containing a photopolymerizable resin is cured by light irradiation, it is difficult to determine only which part has been irradiated with light, that is, which part has been light-cured, based on the appearance alone. For example, it often damages the uncured portion of the coating film and impairs the appearance. Furthermore, in the case of on-site construction where the surface to be coated cannot be moved, such as the floor or wall of a building, when curing a coating film made of a photopolymerizable coating agent, the ultraviolet irradiation device must be moved to cure. In addition, since the movement of the ultraviolet irradiation device is performed artificially, an uncured portion is often left. Workers often enter the uncured portion with the intention of a cured portion, or an ultraviolet irradiation device or a human body comes into contact with the uncured portion, thereby damaging the coating film and impairing the appearance.

[0003] In order to solve such problems, a photopolymerizable paint containing a photochromic compound is applied to the surface to be coated, and then cured while confirming the cured state by the color change of the coated surface by light irradiation. A method for forming a coating film is disclosed in
75. In the gazette, the purpose is to cure the coating film of the photopolymerizable paint applied to the surface to be coated while confirming the cured state under light irradiation, but substantially reduce the entire coating film in a short time. It does not aim to make the original color of the surface to be coated visible when viewed from above the coating film, and no means for achieving the object is disclosed. Further, in the examples in the publication, as the photochromic compound, a compound which develops color by light and decolorizes after removing the light source is used, and further, it is described that the color is decolored 24 hours after the removal of the light source. But
It takes 24 hours and a long time to erase the color (from the example). Furthermore, as a result of additional testing of the method, it could not be said that the color was substantially decolored even after 24 hours, and the color derived from the photochromic compound remained. As described above, the method of the reference is not necessarily a preferable method for on-site construction.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is not only to easily and quickly determine whether or not light irradiation has been performed, that is, whether or not a coating film has been cured. As a result, the photobleachable colorant is substantially decolorized in a short time as compared with the conventional method, and the entire coating film is made substantially transparent so that the original color of the coated surface can be seen when viewed from above the coating film. An object of the present invention is to provide a method for forming a cured coating film. Another object of the present invention is to provide a method for forming a cured coating film that can form a substantially uniform primer layer on the entire surface to be coated without causing uncoated primer or uneven coating.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the primer contains a photobleachable colorant and a photoinitiator as essential components. After applying a photopolymerizable coating agent containing a photopolymerizable resin and a photoinitiator as essential components on the primer layer after application to the surface to form a primer layer, photoirradiation coloring The agent is decolorized in a short time and substantially, and the entire color of the coating film is made substantially transparent so that the original color of the coated surface can be seen when viewed from the top of the coating film, and the portions that have not been irradiated with light and They have found that they can be easily distinguished by visual inspection, and have completed the present invention. In general, a photopolymerizable resin is instantaneously cured by light irradiation. Therefore, according to the method of the present invention, the cured state of a coating film can be determined by a simple method of visually observing a color change of the coating film.

Further, in the method of the present invention, since the primer layer contains a photobleachable colorant, the primer can be applied while visually checking the shading of the color. A substantially uniform primer layer can be formed on the entire surface to be coated with almost no unevenness. Furthermore, in the method of the present invention, when the photopolymerizable coating agent is in the form of an aqueous emulsion system or an aqueous dispersion system, the photopolymerizable coating agent is cloudy, and thus is composed of the applied photopolymerizable coating agent. The residual coating or uneven coating can be easily determined visually by the degree of cloudiness of the layer, so that a substantially uniform layer of the photopolymerizable coating agent can be formed on the entire primer layer. From the above, it can be said that the method of the present invention is an excellent method for on-site construction.

That is, the present invention provides [1] a primer containing a photobleachable colorant and a photoinitiator as essential components on a surface to be coated to form a primer layer, and then the essential components are formed on the primer layer. A method for forming a cured coating film, comprising applying a photopolymerizable coating agent containing a photopolymerizable resin and a photoinitiator as a method and curing the coating film by irradiating light, [2] photobleachable coloring [3] wherein the agent is an azo compound, [3] the method for forming a cured film according to [1] or [2], wherein the method is performed by irradiating light by moving an ultraviolet irradiation device, [4] [1] The method for forming a cured coating film according to any one of the above [1] to [3], wherein the surface to be coated is a floor material, [5] Any one of the above [1] to [4], wherein the primer is in an aqueous form [6] The method for forming a cured coating film according to any of [1] to [5] above, wherein the photopolymerizable coating agent is in an aqueous form. And [7] The photopolymerizable coating agent is in the form or in the form of an aqueous dispersion system of an aqueous emulsion system, a cured coating film forming method of the above-mentioned [6].

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The term "aqueous" in the present invention refers to a system in which the medium may contain water alone or an organic solvent but the total amount is 5% by weight or less. , An aqueous emulsion system, an aqueous dispersion system and the like.

[0009] The primer is a coating solution applied to the lower layer of the photopolymerizable coating agent. The primer of the present invention contains a photobleachable colorant and a photoinitiator as essential components. Irradiation causes decolorization substantially and in a shorter time than in the conventional method. Since the photobleachable colorant does not substantially decolorize in the absence of the photoinitiator, the incorporation of the photoinitiator in the primer was viewed from above the coating as making the entire coating substantially transparent. Sometimes it is very important to make the original color of the coated surface visible.

The photobleachable colorant in the primer is a light-emitting colorant having a wavelength of 200 nm to 800 nm in the presence of a photoinitiator, and then reacts with a radical or light generated from the photoinitiator in a short time (preferably, It is a coloring agent that discolors instantaneously (less than 1 second) and substantially. In the present invention, a short time generally refers to 5 seconds or less, and "substantially bleaching" refers to a state in which it can be visually determined that bleaching has occurred. Examples of the photobleachable colorant include azo compounds and the like, and commercially available UV Red 101, U
V Blue 18, UV Blue 236, UV
Blue 784 (all manufactured by Mitsui Chemicals, Inc.) is particularly preferred. If the content of the photobleachable colorant exceeds 1% of the entire primer, even if the primer contains a photoinitiator, the photobleachable colorant is substantially difficult to decolor, leaving a color, and Since the hue of the coated surface may be impaired, the photobleachable colorant is usually used in an amount of 1% of the entire primer.
%, Preferably 100 ppm or less. In addition, when the content of the photobleachable colorant is less than 1 ppm of the entire primer, the coloring concentration is low, it is difficult to confirm the color at the time of construction, and it is difficult to distinguish between a cured part and an uncured part, The photobleachable colorant is preferably at least 1 ppm, more preferably at least 10 pp, of the entire primer, since it is difficult to determine the uncoated portion and uneven coating.
m or more.

In the present invention, the photoinitiator in the primer means a substance which generates a radical upon irradiation with light, and is not particularly limited as long as it is generally used as a photopolymerization initiator. 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-
[4- (Methylthio) phenyl] -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholino Phenyl) -butane-
1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 1- (4-isopropylphenyl) -2-
Hydroxy-2-methylpropan-1-one, 4′-isopropyl-2-hydroxy-2-methylpropiophenone, etc.), phosphine oxides (for example, bisacylphosphine oxide, acylphosphine oxide, 2,4,6- Trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, benzoyldiethoxyphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc., benzoin alkyl ether (for example, ,
Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, n-butyl benzoin ether, etc., acetophenones (for example, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, acetophenone, 2,2) -Diethoxyacetophenone, chlorinated acetophenone, hydroxyacetophenone, α, α-dichloro-4-phenoxyacetophenone and the like, benzophenone type (for example,
Benzophenone, 4,4'-dichlorobenzophenone,
4,4′-bis (dimethylamino) benzophenone,
4,4′-bis (diethylamino) benzophenone,
3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) benzophenone, 3,3′-dimethyl-4-methoxybenzophenone, etc.),

Thioxanthones (eg, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone), anthraquinones (eg, anthraquinone,
2-ethylanthraquinone, α-chloroanthraquinone, 2-tert-butylanthraquinone, etc.), benzyl type (eg, benzyl, 4,4′-dimethoxybenzyl, 4,4′-dichlorobenzyl, etc.), and benzoic acid ester type (eg, , Methyl o-benzoylbenzoate, p
-Methyl dimethylaminobenzoate, etc.), diketones (e.g., biacetyl, methyl phenylglyoxylate, methylbenzoyl formate, etc.), ketals (e.g., benzyldimethyl ketal, acetophenone diethyl ketal, etc.),

Dibenzocycloalkanones (for example, 1
0-butyl-2-chloroacridone, dibenzosuberone, etc.), acyloxime esters, camphorquinone,
-Ketocoumarin, tetramethylthiuram disulfide,
α, α'-azobisisobutyronitrile, benzoyl peroxide, 2,2'-bis (o-chlorophenyl)
-4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole, acenaphthene, benzalacetone, etc., preferably benzoyl, and 2-hydroxy-
2-Methyl-1-phenylpropan-1-one is particularly preferred.

The amount of the photoinitiator in the primer is not particularly limited. However, if the amount is less than the weight of the photobleachable colorant in the primer, the bleaching by light becomes insufficient. Usually the same weight or more with respect to the photobleachable colorant,
It is preferably blended in a weight of at least 10 times. Further, even if the photoinitiator in an amount exceeding 1000 times the weight of the photobleachable colorant in the primer is blended in the primer, the effect of the decolorization hardly changes, and the photoinitiator of the primer layer is hardly changed. The photoinitiator is preferably not more than 500 times the weight of the photobleachable colorant in the primer, more preferably not more than 2 parts by weight, since the concentration also increases the coating film strength.
It is preferable to mix it up to 00 times the weight.

The primer in the present invention may contain a base resin in addition to the essential components. The base resin in the primer is not particularly limited, and examples thereof include a polyurethane resin, an acrylic resin, an unsaturated polyester resin, an epoxy resin, an acrylic silicone resin, a fluorine-containing resin, an alkyd resin, a urea resin, a melamine resin, a vinyl acetate resin, and cellulose. Natural and synthetic polymers such as resins (eg, nitrocellulose, cellulose acetate butyrate, etc.), oils (eg, rosin derivatives, linseed oil, tung oil, soybean oil, castor oil, etc.), and the like. Polyurethane resins and acrylic resins are preferred because they are unlikely to cause discoloration or deterioration.

As long as the object of the present invention is not impaired, the primer of the present invention may further contain commonly used additives such as a sensitizer, a coloring agent, an antifoaming agent, a defoaming agent, and a wetting agent. Agents, leveling agents, antistatic agents, viscosity modifiers, storage stabilizers, antibacterial agents, preservatives, anti-slip agents, anti-crack agents for coatings, adhesion promoters, dispersants, surfactants, extenders, release agents , A silane coupling agent, a stabilizer, a flame retardant and the like, and these may be used alone or in combination.

The primer of the present invention may be in the form of an organic solvent (for example, an organic solvent such as ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, or mineral spirit), a solvent-free form, or an aqueous form ( Using water as a solvent, for example, an aqueous solution type, an aqueous emulsion type, an aqueous dispersion type, etc.), can take various forms. It is preferable from the viewpoint of the environment and the health of the painter because it does not generate any toxic gas or toxic gas. In addition, since an organic solvent for cleaning is not required, an aqueous form is preferable for on-site construction. Further, since the primer in an aqueous form generally has a low viscosity, it is suitable for a simple application method such as brush, roller, mouton, mop, spraying and the like.

Photopolymerizable Coating Agent The photopolymerizable coating agent of the present invention contains a photopolymerizable resin and a photoinitiator as essential components. The layer composed of the photopolymerizable coating agent has a thickness of 200 nm to 800 nm.
It is cured by being exposed to a wavelength of nm to form a cured coating film.

The photopolymerizable resin in the photopolymerizable coating agent is not particularly limited as long as it is a resin that cures when exposed to a wavelength of 200 nm to 800 nm. For example, unsaturated polyester resin, urethane acrylate resin, epoxy acrylate Resin and the like, and a urethane acrylate resin is preferable.

As the photoinitiator in the photopolymerizable coating agent, those similar to the photoinitiator used in the above “primer” can be mentioned, and the photoinitiator is the photopolymerizable resin in the photopolymerizable coating agent. Usually 0.1 parts by weight.
It is added in an amount of from 0.1 to 10 parts by weight, preferably from 0.1 to 8 parts by weight. The amount of the photoinitiator in the photopolymerizable coating agent is
If the amount is less than 0.01 part by weight with respect to 100 parts by weight of the photopolymerizable resin in the photopolymerizable coating agent, a large amount of ultraviolet light is required to cure the photopolymerizable resin, and the time and equipment are excessively large, and If the amount is more than 10 parts by weight, unreacted photoinitiator may remain in the coating film and deteriorate the coating film performance.

It is preferable to add a reactive diluent to the photopolymerizable coating agent in addition to the essential components. By adding the reactive diluent, the viscosity of the photopolymerizable coating agent can be reduced or the lower layer can be mixed. The coating film performance such as the adhesion of the film and the flexibility of the layer comprising the photopolymerizable coating agent is improved.
In addition, the same photobleachable colorant as that blended with the primer may be blended with the photopolymerizable coating agent, and the blending amount is in the same range as the blending amount of the photobleachable colorant in the primer. Is preferred.

Examples of the reactive diluent include monofunctional monomers (for example, methyl (meth) acrylate and the like),
Bifunctional monomers (such as propylene glycol diacrylate), polyfunctional monomers (such as trimethylolpropane triacrylate) and the like,
These may be used alone or in combination. The reactive diluent can be used in an amount of preferably 0.1 to 99% by weight, more preferably 1 to 50% by weight, based on the entire photopolymerizable coating agent.

The photopolymerizable coating agent may be in the form of an organic solvent (eg, ethyl acetate, butyl acetate, methanol,
Various types of organic solvents such as ethanol, isopropyl alcohol, and mineral spirit), solvent-free forms, and aqueous forms (water is used as a solvent, for example, aqueous solutions, aqueous emulsions, aqueous dispersions, etc.) However, in the case of an aqueous form, it does not generate odor or toxic gas even when the solvent evaporates during drying, which is favorable for the environment and the health of the painter. Since no organic solvent is required, an aqueous form is preferred for on-site construction. The application of the photopolymerizable coating agent may be performed by a conventional method, for example, a roller,
Examples of the method include spraying, brushing, moutons, mops, wax pads, and sponges.

Method for Forming Cured Coated Film The cured coated film of the present invention has a structure of a surface to be coated / a primer layer / a photopolymerizable coating agent. The primer layer of the present invention contains a photobleachable colorant and a photoinitiator as essential components, and the photopolymerizable coating agent contains a photopolymerizable resin and a photoinitiator as essential components. If the film having such a configuration is irradiated with light, the coating is cured, and at the same time, the photobleachable colorant in the primer layer can be substantially decolorized in a short time,
The curing of the coating film can be determined by a simple method of decolorization of the coating film, and the whole coating film can be made substantially transparent in a shorter time than the conventional method. In the on-site construction, it is preferable that the primer and the photobleachable colorant to be used are in an aqueous form from the influence on the human body and the environment.

Hereinafter, the method for forming a cured coating film of the present invention will be described in detail along the procedure. (1) First, a primer is applied to the surface to be coated. Before applying the primer, the surface to be coated may be pretreated. Examples of the pre-treatment on the surface to be coated include pre-treatments that are usually performed,
For example, sanding, degreasing and washing of the surface to be coated can be mentioned. When the surface to be coated is a floor and the surface is coated with wax, wax removal is performed as a pretreatment.
The primer layer has a cured film thickness of usually 0.1 to 100 μm.
m, preferably 1 to 50 μm.

The application of the primer may be carried out by a conventional method, for example, any method using a coating device or a coating device such as a roller, a spray, a brush, a mouton, a mop, a wax pad or a sponge.

When the primer layer is cured, the primer layer is not cured before applying the photopolymerizable coating agent, but is cured simultaneously with the layer composed of the photopolymerizable coating agent after the application of the photopolymerizable coating agent. The photopolymerizable coating agent may be cured before being applied. Of course, when the primer layer is cured only by light irradiation, the former method is used, and when the primer layer is cured by means other than light, either method may be used. Of course, in the case of using the latter method, the photobleachable colorant is cured by a method other than curing by light irradiation, for example, a method such as room temperature curing or heat curing, so as not to substantially decolor the photobleachable colorant.
From the viewpoint of on-site construction, it is preferable to apply a photopolymerizable coating agent after curing the primer layer (except for light curing).

The primer layer in the present invention contains a photobleachable colorant, and the primer can be applied while visually checking the color density. In addition, a substantially uniform primer layer can be formed on the entire surface to be coated. In addition, the primer layer suppresses the penetration of the photopolymerizable coating agent to the surface to be coated, and controls the dry thickness of the coating film accurately, and the adhesion between the layer composed of the photopolymerizable coating agent and the surface to be coated. Or a releasability from the surface to be coated.

(2) Next, a photopolymerizable coating agent is applied on the primer layer. The photopolymerizable coating agent may be applied on the primer layer so that the cured film thickness of the layer composed of the photopolymerizable coating agent is preferably 1 μm or more, more preferably 5 μm or more. The cured film thickness of the layer composed of the photopolymerizable coating agent is 1000 μm.
m, preferably 500 μm or less. When the film thickness after curing exceeds 1000 μm, the coating operation takes a long time, the time required for drying and curing the coating film and the amount of irradiation also increase, and the coating film cracks due to shrinkage and the surface to be coated is warped. May easily become large. The application of the photopolymerizable coating agent may be performed in the same manner as the application of the primer.

The photopolymerizable coating agent is cloudy as in an aqueous emulsion system or an aqueous dispersion system. (In an aqueous emulsion system, the emulsifier causes the photopolymerizable coating agent component to form droplets and be dispersed in water;
In the case of the aqueous dispersion system, the photopolymerizable coating agent component is dispersed as particles). Therefore, it is possible to form a substantially uniform layer of the photopolymerizable coating agent over the entire primer layer.

In the present invention, it is necessary to remove the solvent by drying the layer if a solvent remains in the layer when performing any curing. Drying of each layer can be usually performed by a method of drying a paint (for example, natural drying, hot air drying, and the like).

(3) The coating film is cured. (1) and (2) above
Is cured by light irradiation. The light irradiation method is not particularly limited, and the surface to be coated cannot be moved during on-site construction. Therefore, it is preferable to perform light irradiation by moving an ultraviolet irradiation device. What is an ultraviolet irradiation device?
This is an apparatus in which a light source for generating ultraviolet light and visible light having a wavelength in the range of 200 nm to 800 nm, an irradiation unit formed of a reflector, a power supply, a power cord, and a cooling fan are integrated. Regarding these ultraviolet irradiation devices and methods of using them, see Japanese Patent Publication No. 258810 and US Pat.
No. 6,383 and the like. 200 nm to 80
The light source that generates ultraviolet light and visible light having a wavelength in the range of 0 nm is not particularly limited, and includes, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp,
Xenon lamps and the like.

The irradiation amount on the irradiation surface is preferably 1 to 50
00 mJ / cm ² , more preferably 10 to 300
0 mJ / cm ² . Since the coating film of the present invention can be substantially decolorized in a short time even with a relatively low irradiation amount, the irradiation amount may be appropriately adjusted within the above range. When the irradiation amount of light at the irradiated surface is less than 1 mJ / cm ^2, there is a risk that may remain unreacted component or the curing rate becomes slow in the coating, when the light quantity exceeds 5000 mJ / cm ^2, the When using equipment with a low irradiation capacity, a long irradiation time is required, and when trying to irradiate the irradiation light amount in a short time, equipment with a high irradiation capacity is required, which increases the equipment cost, and in addition, increases the coating cost. There is a risk of film deterioration.

The method for forming a cured coating film of the present invention can be applied to various uses, and can also be applied to on-site construction. For example, the present invention is also useful when the surface to be coated is a flooring material, and the “flooring material” in the present invention may have any form and state as long as it is made of a material commonly used for flooring. Good. As the floor material, for example, i) a resin-based material such as vinyl chloride, ii) a wood-based material such as flooring, iii)
Ceramic materials such as porcelain tiles, iv) stone materials such as marble, and v) concrete materials such as mortar.

The method for forming a cured coating film of the present invention can be applied to a coated floor material having a coating film on the surface of the floor material. There is no particular limitation as long as it is used as a material of a coating film provided on the surface of the coated flooring material, and examples thereof include an epoxy resin, a urethane resin, an acrylic resin, an MMA resin, and a polyester resin.

I) Flooring materials of resinous materials such as vinyl chloride include vinyl floor tiles such as composition vinyl floor tiles, homogeneous vinyl floor tiles, foamed vinyl floor sheets such as cushion floors, woven laminated vinyl floor sheets, and the like.
Examples include vinyl floor sheets such as nonwoven laminated vinyl floor sheets, linoleum flooring, natural material tiles such as cork tiles and rubber tiles.

Ii) Examples of flooring materials of wood-based materials such as flooring include single-layer flooring, composite flooring, flooring board, flooring block, mosaic parquet, soundproof floor, soundproof double floor, and free access floor.

Iii) As a floor material of a ceramic material such as a porcelain tile, a porcelain tile, a porcelain block, a non-slip tile or the like can be used in addition to the porcelain tile.

Iv) As a floor material of a stone material such as marble,
In addition to marble, terrazzo such as granite, resin terrazzo and cement terrazzo may be mentioned.

[0040]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, (1) whether uncoated or uneven coating can be easily visually confirmed at the time of primer application, and (2) the cured state of the coated film after light irradiation were determined by decolorization of the coated film. I checked if it could be done.
(2) was performed immediately after light irradiation. Also, (1)
In the above, ○ when it can be visually confirmed, × when it cannot be confirmed; in (2), when it can be visually confirmed that the color of the coating film has been bleached 5 seconds after the removal of the ultraviolet irradiation device, When the color colored by the primer layer can be visually confirmed as remaining even after more than 5 seconds from the removal of the ultraviolet irradiation device, it was evaluated as x, and the results are summarized in Table 1. Note that “parts” means parts by weight, and all “%” are% by weight.

Example 1 A polyurethane resin comprising an aqueous emulsion (Avisia)
50 parts of Neoretz R972 (39% solids)
Dilute with 50 parts of water, and use UV as a photobleachable colorant there
BLUE 784 (manufactured by Mitsui Chemicals, Inc.) at 0.005
% And Darocur 1173 as photoinitiator (Ciba
Specialty Chemicals Co., Ltd.) 1%
Was used as a primer. Prepare the primer with white poly
Roller so that the cured film thickness is 5 μm on the ester decorative board
And left at room temperature for 30 minutes to cure the coating
did. When applying the primer, the primer
It was determined whether the coating unevenness could be visually confirmed.
Furthermore, as a photopolymerizable coating agent,
Topcoat (produced by Gen Technology Research Institute; aqueous emulsion)
System; photopolymerizable resin containing photoinitiator, photopolymerizable resin: photoinitiated
Agent content ratio = 100: 8 (weight)) cured with a roller
Was applied to be 15 μm. To evaporate the solvent
After leaving at room temperature for one hour, a mobile ultraviolet irradiation device (L
100m using Gen 100
J / cm ^TwoWas irradiated. At this time, do you bleach instantly?
Whether it was visually determined.

Example 2 A solvent-type two-pack polyurethane resin paint (V Rose, Genro Chemical Co., Ltd., solid content: 25%) was blended as prescribed, and UV BLUE 236 (Mitsui Chemicals, Inc.) was used as a photobleachable colorant. ) And 0.1% of Darocur 1173 (manufactured by Ciba Specialty Chemicals) as a photoinitiator were used as primers. The prepared primer was applied to a white polyester decorative board by spraying so as to have a cured film thickness of 10 μm, and left at room temperature for 2 hours to cure the coated film. When the primer was applied, it was determined whether or not uncoated primer and uneven coating could be visually confirmed. Further, as a photopolymerizable coating agent, Winup Topcoat (produced by Gen Technical Research Institute Co., Ltd .; aqueous emulsion system); photopolymerizable resin containing photoinitiator, photopolymerizable resin: photoinitiator content ratio = 100: 8. (Weight)) was applied using a roller so that the cured film thickness became 15 μm. After leaving at room temperature for 1 hour to evaporate the solvent,
Light of 1500 mJ / cm ² was irradiated using an ultraviolet irradiation device (H05-L21 manufactured by Eye Graphic Co., Ltd.). At this time, whether or not the coating film was immediately decolorized was visually determined.

Comparative Example 1 Darocure 1173 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photoinitiator was not blended in the primer.
The procedure was exactly the same as in Example 1 except that the primer was applied so that the cured film thickness became 5 μm. 24 paint colors
It did not completely discolor even after the passage of time.

Comparative Example 2 The procedure of Example 2 was repeated except that UV BLUE 784 (manufactured by Mitsui Chemicals, Inc.) as a photobleachable colorant was not blended in the primer and the primer was applied so that the cured film thickness was 5 μm. Performed exactly as in 1. Since there was no color of the coating film before light irradiation, it was not possible to visually confirm that the entire coating film was substantially transparent.

Comparative Example 3 The procedure was the same as in Example 2 except that Darocure 1173 (manufactured by Ciba Specialty Chemicals), which was a photoinitiator, was not used in the primer. The color of the coating film did not completely decolor after 24 hours.

[0046]

[Table 1]

[0047]

According to the method of the present invention, the curing of the coating film can be judged by a simple method of decolorization of the coating film, and the color of the entire coating film can be determined in a shorter time than the conventional method. It is practically transparent, and the original color of the surface to be coated can be seen when viewed from the top of the coating, so that it is possible to prevent the ultraviolet irradiation device and the human body from coming into contact with the uncured part beforehand, causing damage to the coating. It can be said that this method is efficient because it reduces the need for rework and reduces the need for rework, and is an excellent method for on-site construction. In addition, in the method of the present invention, since the primer layer contains a photobleachable colorant, the primer layer can be applied while visually checking the shading of the color. A substantially uniform primer layer can be formed on the entire surface to be coated without generation. Thereby, the quality of the coating film can be stably maintained. Furthermore, in the method of the present invention, when the photopolymerizable coating agent is in the form of an aqueous emulsion system or aqueous dispersion system, the photopolymerizable coating agent is cloudy, so The residual coating and uneven coating can be easily determined visually by the degree of cloudiness of the layer to be formed, so that a substantially uniform layer of the photopolymerizable coating agent can be formed on the entire primer layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C09D 5/00 C09D 5/00 D 7/12 7/12 201/00 201/00 F-term (reference) 4D075 AE03 BB42Z BB46Z BB54Z CA13 CA47 CB06 DA06 DA23 DA25 DB12 DB14 DB20 DB21 DB35 DB38 DB43 DB47 DB48 DB50 DC02 EA06 EA07 EA13 EA41 EB07 EB16 EB19 EB22 DD EB24 EB32 EB33 EB35 EB36 EB1 EC02 EC07 EB11 EC02 EC07 DD231 DG001 DL031 JB16 KA03 KA08 MA08 NA01 PA12 PA17 PB05

Claims (7)

[Claims] 1. A primer containing a photobleachable colorant and a photoinitiator as essential components is applied to a surface to be coated to form a primer layer, and then a photopolymerizable resin and a photopolymer as essential components are formed on the primer layer. A method for forming a cured coating film, comprising applying a photopolymerizable coating agent containing an initiator, and curing the coating film by irradiation with light. 2. The photobleachable colorant is an azo compound.
The method for forming a cured coating film according to claim 1. 3. The method for forming a cured coating film according to claim 1, wherein the light irradiation is performed by moving an ultraviolet irradiation device. 4. The method according to claim 1, wherein the surface to be coated is a floor material. 5. The method for forming a cured coating film according to claim 1, wherein the primer is in an aqueous form. 6. The method for forming a cured coating film according to claim 1, wherein the photopolymerizable coating agent is in an aqueous form. 7. The method according to claim 6, wherein the photopolymerizable coating agent is in the form of an aqueous emulsion or an aqueous dispersion.