JP4601977B2 - Method for curing coating film comprising photocurable coating composition, coating film formed by the method, and substrate coated with the coating film - Google Patents

Description

  The present invention relates to a method for curing a coating film comprising a photocurable coating composition, a coating film formed by the method, and a substrate coated with the coating film, and more particularly, the photocurable coating composition used. Even if the photopolymerization initiator content is further reduced, it has excellent hardness, chemical resistance, stain resistance, and anti-cracking property, excellent low odor of the coating, and low gloss cured film. The present invention relates to a method for curing a coating film comprising a photocurable coating composition, a coating film formed by the method, and a substrate coated with the coating film.

Conventionally, as a curing method for a photocurable coating composition applied to the surface of a wooden substrate or the like, an ultrahigh pressure or high pressure mercury lamp, a metal halide lamp, or an ultraviolet fluorescent light source that emits light having a wavelength of about 200 to 600 nm. A UV curing method using a lamp (chemical lamp), a xenon lamp, sunlight or the like is widely adopted, and is cured by, for example, a short UV irradiation of about several tens of seconds to 0.1 seconds (for example, special JP 2001-340799 A, JP 2003-171 A
No. 459, JP-A No. 2003-290707, JP-A No. 07-171491, etc.).

  However, in the case of the conventional UV curing method using a high-pressure mercury lamp etc., the hardness, chemical resistance, stain resistance, and dry crack resistance of the resulting cured coating film, and further photopolymerization starts There was room for further improvement in terms of the amount of the agent used and the low odor of the coating film.

  Therefore, the present inventors have conducted extensive research and found that when an electrodeless UV lamp, which is a specific UV lamp, is used, compared with the case of using a normal high-pressure mercury lamp, the coating film hardness, chemical resistance, It has been found that the above problems can be solved at once, such as excellent coating performance such as contamination and dry cracking resistance, reducing the amount of photopolymerization initiator used, and excellent low odor of the coating. . However, in finishing wood substrates, low gloss products occupy most of the demand, but when only electrodeless UV lamps are cured, gloss increases and low gloss is difficult.

Therefore, as a result of further earnest research, prior to complete curing with an electrodeless UV lamp, irradiation with a high-pressure mercury lamp or metal halide lamp in advance and semi-cure (semi-curing) is performed, and then irradiation with an electrodeless UV lamp is performed. The inventors have found that when the film is completely cured, it is possible to reduce the gloss of the coating film, and the present invention has been completed.
JP 2001-340799 A JP 2003-171459 A JP 2003-290707 A Japanese Patent Application Laid-Open No. 07-171491

  The present invention is intended to solve the problems associated with the prior art as described above, and has better performance such as hardness, chemical resistance, stain resistance, and resistance to dry cracking, and low odor of the coating film. A coating method comprising a photocurable coating composition, a coating film formed by the method, and a substrate coated with the coating film so that a low-gloss cured coating film having excellent properties can be obtained. The purpose is to do.

In the present invention, a photocurable coating composition containing (A) a photocurable resin, (B) a photopolymerization initiator, and (C) an extender pigment is applied onto a wooden substrate, and then a high pressure mercury lamp or a metal halide is applied. It is characterized by being completely cured by irradiating an electrodeless UV lamp after semi-curing (semi-curing) with a lamp.

  In the present invention, the photocurable resin (A) is at least one photocurable resin selected from the group consisting of an acrylic resin having a photopolymerizable (meth) acryloyl group, urethane acrylate, epoxy acrylate, and polyester acrylate. A resin is preferred.

  In the present invention, the photopolymerization initiator (B) is a photopolymerization initiator selected from the group consisting of benzophenones, anthraquinones, thioxanthones, acetophenones, acylphosphine oxides, and methylphenylglyoxyesters. It is preferable.

In the present invention, the extender pigment (C) is silica (SiO ₂ ), talc [Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ ], precipitated barium sulfate (BaSO ₄ ), barium carbonate (BaCO ₃ ), Calcium carbonate (CaCO ₃ ), alumina white (Al ₂ (OH) ₃ ), precipitated magnesium carbonate [M
gCO ₃ .3Mg (OH) ₂ .H ₂ O], polyethylene wax, bead pigments, etc., have a low refractive index per se, and have a concealing property (the property that the pigment, paint, etc. completely covers the black and white base). Although it does not matter, it is preferably one or more extender pigments selected from the group consisting of white pigments used for reducing gloss.

In the present invention, the photopolymerization initiator (B) is in the range of 1 to 15 parts by weight and the extender pigment (C) is in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the photocurable resin (A). Is preferably used.

  In the present invention, one or more of a sealer coating, an undercoat coating, and an intermediate coating are formed in that order in advance on a wooden substrate, and the outermost layer of these coatings is applied. It is preferable that the photocurable coating composition is applied onto the film and semi-cured (semi-cured) with a high-pressure mercury lamp or a metal halide lamp, and then irradiated with an electrodeless UV lamp to be completely cured.

In the present invention, the irradiation of the electrodeless UV lamp for complete curing is performed by placing one or more electrodeless lamps on a conveyor at a predetermined distance, and the photocurable coating composition is It is preferable to carry out by applying the coated wood base material to a conveyor at a speed of 1 to 150 m / min.

In the present invention, an electrodeless UV lamp having an output of 24 to 240 W / cm per unit is applied to a wood base material coated with a photocurable coating composition, and the integrated light quantity is 100 to 3000 mJ / cm ^2.
It is preferable to completely cure a semi-cured ( semi-cured ) coating film made of a photocurable coating composition.

In the present invention, on the wooden substrate, at least one of a sealer coating, an undercoat coating, and an intermediate coating is applied in that order in advance, and irradiation with a high-pressure mercury lamp or a metal halide lamp is performed. The above-mentioned photo-curable coating composition is applied onto the outermost coating film of these coating films, semi-cured (semi-cured) with a high-pressure mercury lamp or metal halide lamp, and then an electrodeless UV lamp is used. It is preferable to completely cure by irradiation.

The photocured coating film according to the present invention is preferably a photocured coating film formed by any of the methods described above.
The base material with a coating film according to the present invention is characterized in that the surface of the wooden base material is coated with a photocured coating film formed by any of the methods described above.

  In the present invention, when the photocurable coating composition is cured, instead of a normal high-pressure mercury lamp or metal halide lamp, it is semi-cured (semi-cured) with a high-pressure mercury lamp or metal halide lamp and then irradiated with an electrodeless UV lamp. The photopolymerization initiator is completely cured, has excellent properties such as hardness, chemical resistance, stain resistance, and anti-cracking properties, is capable of low gloss, and is incorporated into the photocurable coating composition. A use amount can be reduced and the cured coating film excellent in the low odor property of the coating film is obtained.

  Moreover, according to this invention, the coating-material base material of the said characteristic which is a coating film of the said characteristic formed by said method and the base material coat | covered with the coating film is provided.

Hereinafter, a method for curing a coating film comprising the photocurable coating composition according to the present invention, a coating film formed by the method, and a substrate coated with the coating film will be specifically described.
<Curing method of coating film comprising photocurable coating composition>
In the method for curing a coating film comprising the photocurable coating composition according to the present invention, on a wooden substrate, (A) a photocurable resin, (B) a photopolymerization initiator, and (C) an extender pigment. After the photocurable coating composition is applied, the surface of the uncured coating film is irradiated with a high-pressure mercury lamp, metal halide lamp, etc., and semi-cured (semi-cured), and then irradiated with an electrodeless UV lamp to completely cure ( (Main curing).

  As the photo-curable coating composition, either solvent-based or solvent-free can be used, but in the present invention, the solvent-free coating can accelerate the curing reaction, has excellent coating workability, and is environmentally friendly. It is desirable in that it has less fear of contamination and is excellent in terms of environmental response.

  In the present invention, prior to applying and curing the photocurable coating composition on the surface of the wooden substrate, any one of a sealer coating, an undercoat coating and an intermediate coating is applied in this order as necessary. It is preferable to apply the photo-curable coating composition on the outermost layer of these coating films, and after semi-curing as described above, irradiating with an electrodeless UV lamp and completely curing. Curing of these sealer coating, undercoat coating, intermediate coating, etc. may be carried out using any of a high pressure mercury lamp, a metal halide lamp and an electrodeless UV lamp, but a high pressure mercury lamp and a metal halide lamp are preferred.

  As the coating material for sealer coating film (sealer), coating material for undercoat coating film (undercoating coating material), and coating material for intermediate coating film (intermediate coating coating material), any of solvent type and solventless can be used. It is desirable that all of these are solvent-free in view of the fact that the curing reaction can proceed rapidly, the coating workability and the response to the environment are excellent.

In the present invention, the extender pigment contained in the semi-cured coating film is oriented by semi-curing the photo-curable coating composition layer that is the outermost layer, and the method for measuring the specular gloss of JIS-K-5600 The value measured at an incident angle of 60 degrees ”is 30 or less, preferably 10-30.
<Electrodeless UV lamp irradiation>
The electrodeless UV lamp used in the present invention excites a light-emitting substance such as mercury inside the lamp into a plasma state by the energy of a microwave (eg, 2450 MHz) generated by a magnetron, and converts the microwave into light energy. Unlike conventional high-pressure mercury lamps, it does not have electrodes inside the lamp.

As an electrodeless UV lamp, it is preferable that "Fusion"
“MODEL VSP / I600” manufactured by “UV systems JAPAN KK”
(Light source unit maximum output: 240 W / cm), “VSP / I250” (light source unit maximum output: 150
More specifically, as shown in FIG. 1, for example, as in the case of the mercury spectrum, “H bulb”, “H bulb”, and “H” having strong emission peaks in the 200 to 280 nm region and around 365 nm. Compared to the “bulb”, the “H plus bulb” has an emission output in the short wavelength range (200 to 280 nm) that is increased by about 15% on average. The bulb has a particularly strong emission peak in the 350 to 400 nm range. "D bulb" suitable for curing, bulb with strong emission peak in the range of 405 to 425 nm centering around 420 nm, suitable for UV curing of thick film paints such as white base coat containing titanium oxide and laminate materials “Bulb”, “Q bulb” having a strong emission peak at 400 to 460 nm, which is slightly longer than the V bulb, 365 to 369 nm, and 406 n Examples thereof include “M bulb” which has an emission peak output in the vicinity of m and is suitable for curing an exterior coating or the like which requires weather resistance.

  In selecting a bulb (lamp), a bulb having a suitable emission spectrum may be selected in consideration of the type of photocurable coating composition to be used, curing conditions, coating thickness, type of material, and the like.

  In the present invention, considering the application, the type of the photocurable coating composition, the curing conditions, the coating thickness, etc., among these valves, “H bulb” having a strong emission peak in the 200 to 280 nm region and around 365 nm. And “H plus valve” are preferable in terms of the type of photopolymerization initiator used and the curing performance of the coating film surface, compared with other valves, in curing the photocurable coating composition of the outermost layer. .

The high pressure mercury lamp takes a long time to restart once the lamp is turned off, but the electrodeless UV lamp can be easily restarted, and the loss of working time can be reduced.
The curing treatment (main curing, complete curing) of the uncured photocurable coating composition coating film using such an electrodeless UV lamp is, for example, H-type, D-type, etc., manufactured by Fusion UV Systems, Inc. with 240 W output. In the case of using one or more electrodeless UV lamps, the lamps are arranged at a distance of about 5 to 10 cm from the surface of the uncured photocurable coating composition applied to the surface of the wooden substrate. What is necessary is just to convey a wooden base material with a belt conveyor etc. at a speed | rate of about -150m / min (example: 10m / min).

In the case of an electrodeless UV lamp having an output of 24 to 240 W / cm per lamp, the wood substrate to which the photocurable coating composition is applied is irradiated in an amount such that the integrated light quantity is 100 to 3000 mJ / cm ^2. A semi-cure ( semi-cured ) coating film may be completely cured.

  In the present invention, a photocurable coating composition is applied onto a wooden substrate, and is “semi-cured (semi-cured)” with a high-pressure mercury lamp (wavelength: 254 to 560 nm), a metal halide lamp (wavelength: 254 to 560 nm), or the like. Later, by irradiating an electrodeless UV lamp to “completely cure (main cure)”, the cured coating has low gloss, low odor, degree of cure, scratch resistance, stain resistance, chemical resistance, drought resistance More preferable from the viewpoint of cracking property.

The difference between the semi-cure (semi-curing) condition and the main curing (complete curing) condition is as follows.
The semi-cured (semi-cured) state means that the paint has begun to harden but has not completely hardened as defined in the “0012” column of Japanese Patent Laid-Open No. 2002-361173 previously proposed by the applicant of the present application. refers to the state, the acetone extraction gel fraction is less than 1 0% by weight to 90% by weight, preferably 10 to 60 wt%, more preferably in the state of 20 to 50 wt%. In complete curing, the semi-cured state is removed and the acetone extraction gel fraction is 90% by weight or more.

By the way, in the present invention, a low-gloss coating is efficiently obtained, which is considered to be due to the following reasons.
That is, the electrodeless UV lamp has a high output, and the uncured coating film has a strong tendency to be cured instantaneously. Therefore, the surface characteristics of the obtained cured coating film are excellent because the influence of oxygen inhibition on the coating film surface is small. On the other hand, even if the amount of extender pigment is increased, the orientation is poor and it is relatively difficult to reduce the gloss of the coating film.

Therefore, by incorporating a semi-cure (semi-curing) process with a high-pressure mercury lamp, metal halide lamp, etc. in advance so as not to impair the advantages of the coating film cured with an electrodeless UV lamp, The orientation is good and a desired low gloss coating is obtained.
<Photocurable coating composition>
In the present invention, the photocurable coating composition contains a photocurable resin (A), a photopolymerization initiator (B), and an extender pigment (C). Among these, a photocurable resin ( A) is a resin that cures using an ultraviolet region (200 to 600 nm, preferably 200 to 400 nm) in an electromagnetic wave, and is an active double compound such as a (meth) acryloyl group, a vinyl group, or an unsaturated dicarboxylic acid ester. Examples include radical polymerization of those having a bond, cationic polymerization of those having an epoxy group, and curing using an addition reaction between a thiol group and a double bond group.

  Usually, such a resin (A) and a photopolymerization initiator (B) that is easily photoexcited are used in combination, and radical or cation active species are generated by cleavage of the initiator or hydrogen transfer with ultraviolet rays. This active species acts on the resin to cause polymerization or cross-linking reaction, and cures in an extremely short time.

  In the present invention, as the photocurable resin (A), those having a (meth) acryloyl group which is a photopolymerizable double bond (C = C) are preferably used, and a photopolymerizable acrylic resin or urethane is used. An acrylate, an epoxy acrylate, and a polyester acrylate are more preferable, and these photocurable resins are used alone or in combination.

  Examples of the photopolymerization initiator (B) include benzophenones, anthraquinones, thioxanthones, acetophenones, acylphosphine oxides, and methylphenylglyoxyesters.

The extender pigment (C) includes silica (SiO ₂ ) and talc [Mg ₃ (Si ₄ O ₁₀ ) (OH) _2.
], Precipitated barium sulfate (BaSO ₄ ), barium carbonate (BaCO ₃ ), calcium carbonate (CaCO ₃ ), alumina white (Al ₂ (OH) ₃ ), precipitated magnesium carbonate [MgCO ₃ .3Mg (OH) _2. And white pigments such as H ₂ O], polyethylene wax, and bead pigments.

The above bead pigments are the usual pigments “Fe ₂ O ₃ , TiO ₂ , CaCO ₃ , quinacridone {7,16-dihydro-7,16-dimethylbenzo [a] benzo [5,6] quino [3,6] quino [3,6]. 2-I] acidine-9,18-dione, manufactured by HW SANDS CORP. Or manufactured by Nagase Sangyo Co., Ltd., trade name} ", and the like, polyurethane, acrylic resin, epoxy resin, polyester, In elastic resin such as polyamide (nylon (R)), fluororesin, vinyl chloride-vinyl acetate copolymer, etc., or plasticizer, stabilizer, surface activity as required for these elastic resins It is formed by coating with an agent or the like and granular.

  In the present invention, the extender pigment (C) itself has a low refractive index and does not contribute to improving the concealing property (the property that the pigment, paint, etc. completely covers the black-and-white base) and relates to the concealing property. The white pigment that can reduce gloss is preferably used.

  The photocurable coating composition of the present invention includes a polymerizable monomer having a polymerizable double bond such as a (meth) acryloyl group or a vinyl group, various additives (eg, antifoaming agent, leveling agent, pigment dispersion). Agent) and the like.

In the present invention, the photopolymerization initiator (B) is usually used in an amount of 1 to 15 parts by weight, preferably 3 to 6 parts by weight, based on 100 parts by weight of the photocurable resin (A). Usually 1-30
Use in an amount of parts by weight, preferably 5 to 15 parts by weight, is desirable from the viewpoint of the curing rate of the applied uncured coating film, the low odor of the cured coating film, and the hue of the cured coating film.

  In the present invention, any of a sealer coating, an undercoat coating, and an intermediate coating may be applied in advance on the wooden substrate. When all of these sealer coating, undercoat coating, and intermediate coating are applied, the order of lamination is “woody substrate / sealer coating / undercoating coating / intermediate coating / photocurability”. What is necessary is just to apply | coat so that it may become a "coating film consisting of a coating composition." In the case of excluding or omitting any coating film, for example, an undercoating film, while maintaining this order, “consisting of“ woody substrate / sealer coating / intermediate coating film / photocurable coating composition ”. What is necessary is just to apply in the order of "coating film".

  In this way, when any one or more of a sealer coating, an undercoat coating, and an intermediate coating are applied on the wooden substrate in advance, a high-pressure mercury lamp or a metal halide lamp is applied after each coating is applied. Irradiation can be performed. Then, the photocurable coating composition to be a surface layer (also referred to as an outermost layer or an overcoat layer) is applied on the last coating film (layer) of these coating films, for example, on the intermediate coating film. In addition, after performing the semi-cure (semi-curing) process using a high-pressure mercury lamp, a metal halide lamp, or the like as described above, it is preferable to irradiate an electrodeless UV lamp and completely cure it.

In applying these paints, any known method such as roll coater, flow coater, knife coater, air spray, airless spray, brush, etc. may be used.
<Hardened coating film and substrate with the coating film>
The photocured coating film according to the present invention is formed by any of the methods described above.

The thickness of the coating film varies depending on the type of end product, application, etc., and is not generally determined, but is, for example, about 5 to 200 μm (thickness).
The base material with a coating film according to the present invention is characterized in that the surface of the wooden base material is coated with a photocured coating film formed by any of the methods described above.

The wood substrate is not particularly limited, such as wood, plywood, and laminated wood.
As described above, the coating film is formed in the order of, for example, “woody base material / sealer coating film / undercoat coating film / intermediate coating film / coating film made of a photocurable coating composition”. The thickness of each layer (coating film) in that case is not particularly limited, but is a dry film thickness, sealer coating film: about 3 to 10 μm (thickness), undercoat coating film: about 10 to 30 μm (thickness), intermediate coating film About 10 to 50 μm (thickness), coating film made of a photocurable coating composition: about 10 to 100 μm (thickness).

In addition, the sealer coating film, the undercoat coating film, and the intermediate coating film provided as necessary may not include any of these coating films, or may not include all of them.
<Effect of the invention>
In the present invention, when UV-curing an uncured coating film made of a photocurable coating composition, it is semi-cured ( semi-cured ) with a normal high-pressure mercury lamp or metal halide lamp in advance, and then compared with these high-pressure mercury lamps and metal halide lamps. The main curing (complete curing) is performed using an electrodeless UV lamp capable of irradiating with higher energy in a predetermined wavelength range, and compared with the case of using a normal high-pressure mercury lamp or metal halide lamp. The coating film performance tends to be improved, and for example, a cured coating film having excellent performance such as hardness, chemical resistance, contamination resistance, and anti-cracking resistance can be obtained.

  In the present invention, since a high-power electrodeless UV lamp is used for curing the photocurable coating composition as described above, the blending amount of the photopolymerization initiator in the photocurable coating composition to be used The resulting coating film is excellent in low odor.

Further, in the present invention, when UV-coating a coating film made of a photocurable coating composition, it is semi-cured (semi-cured) with a high-pressure mercury lamp or metal halide lamp having a light emission peak in the wavelength region in advance, and then in the wavelength region. Since the main curing (complete curing) is performed by irradiating a higher-power electrodeless UV lamp having an emission peak, only the electrodeless UV lamp irradiation is performed without semi-cure treatment using a high-pressure mercury lamp or a metal halide lamp. Compared to the case where it is carried out, the cured coating film has a lower gloss, and the cured coating film has excellent performance such as low odor, hardness, chemical resistance, stain resistance, and dry cracking resistance. Is obtained.
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by the Example concerned.

Next, undercoat UV curable composition (undercoat paint), intermediate coat UV curable composition (intercoat paint), top coat UV curable composition (top coat paint) used in the following Examples and Comparative Examples ).
[Preparation of coating composition]
<Preparation of UV curable composition for undercoat (undercoat)>
As UV curable composition for undercoat, “Hitaroid 4860” (Hitachi Chemical Co., Ltd., urethane acrylate resin) 30 parts by weight,
"ACMO" (manufactured by Kojinsha, acrylic monomer) 30 parts by weight,
"Beam set 770" (Arakawa Chemical Co., Ltd., vinyl monomer) 5 parts by weight,
"Irgacure 184" (Ciba Specialty Chemicals, photopolymerization initiator) 5 parts by weight,
30 parts by weight of “MINEX10” (made by UNIMIN CANADA, extender pigment) was added and stirred to prepare an ultraviolet curable composition for undercoating.
<Preparation of UV-curable composition for intermediate coating (intermediate coating)>
As an ultraviolet curable composition for intermediate coating, “Lipoxy VR-77” (manufactured by Showa Polymer Co., Ltd., epoxy acrylate resin) 45 parts by weight,
"TRPGDA" (manufactured by Daicel UCB, acrylic monomer) 25 parts by weight,
"New Frontier TMP-3" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 15 parts by weight, "Irgacure 184" (Ciba Specialty Chemicals, photopolymerization initiator) 3 parts by weight,
30 parts by weight of “MINEX10” (made by UNIMIN CANADA, extender pigment) was added and stirred to prepare an ultraviolet curable composition for intermediate coating.
<Preparation of UV curable composition (i) for top coating>
As UV curable composition (coating material) (i) for top coating, 40 parts by weight of “UV-55” (manufactured by Akira Ohtake Shin Chemical Co., Ltd., urethane acrylate resin),
"GX-8301S" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 30 parts by weight,
"TRPGDA" (manufactured by Daicel UCB, acrylic monomer) 15 parts by weight,
"New Frontier TMP-3" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 5 parts by weight, "Irgacure 184" (Ciba Specialty Chemicals, photopolymerization initiator) 5 parts by weight,
It was prepared by adding 5 parts by weight of “Mizukaseal P-802Y” (Mizusawa Chemical Co., Ltd., extender pigment) and stirring.
<Preparation of UV curable composition (ii) for top coating>
As UV curable composition (paint) (ii) for overcoating, 40 parts by weight of “UV-72” (manufactured by Akira Ohtake Shin Chemical Co., Ltd., urethane acrylate resin),
"GX-8301S" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 30 parts by weight,
"TRPGDA" (manufactured by Daicel UCB, acrylic monomer) 15 parts by weight,
"New Frontier TMP-3" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 5 parts by weight, "Irgacure 184" (Ciba Specialty Chemicals, photopolymerization initiator) 5 parts by weight,
It was prepared by adding 5 parts by weight of “Mizukaseal P-802Y” (Mizusawa Chemical Co., Ltd., extender pigment) and stirring.
<Preparation of UV curable composition (iii) for top coating>
As a UV curable composition (paint) (iii) for top coating, 40 parts by weight of “UV-72” (manufactured by Akira Otake, urethane acrylate resin),
"GX-8301S" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 24 parts by weight,
"TRPGDA" (manufactured by Daicel UCB, acrylic monomer) 15 parts by weight,
"New Frontier TMP-3" (Daiichi Kogyo Seiyaku Co., Ltd., acrylic monomer) 5 parts by weight, "Irgacure 184" (Ciba Specialty Chemicals, photopolymerization initiator) 8 parts by weight,
It was prepared by adding 8 parts by weight of “Mizukaseal P-802Y” (Mizusawa Chemical Co., Ltd., extender pigment) and stirring.

(Preparation of wooden flooring)
If it is 12mm thick, apply colored stain on a veneer plywood with a roll coater, dry at 80 ° C for 1 minute, and then use "AULEX No. 822F-2" (made by China Paint Co., Ltd., urethane acrylate) as an undercoat UV curable composition) was applied with a roll coater and cured with a high pressure mercury lamp.

Next, “AUREX No. 673B” (manufactured by China Paint Co., Ltd., epoxy acrylate UV curable composition) is applied as an intermediate coating, cured with a high-pressure mercury lamp in the same manner as above, and finally the top coating The UV curable composition (i) is applied with a flow coater, semi-cured with a high-pressure mercury lamp, and then completely cured with an “electrodeless UV lamp (H bulb)” (manufactured by Fusion UV Systems) (main curing) To obtain a wooden floor coating.
(Curing conditions)
(B) High-pressure mercury lamp: Using a high-pressure mercury lamp manufactured by iGraphics, the distance from the object to be coated is 15 cm at a height of 80 W / cm, and it is conveyed at a speed of 10 m / min, and the integrated light quantity is 75 mJ / cm ² Irradiated in an amount to cure.

In the case of semi-curing with the high-pressure mercury lamp, the coating speed was semi-cured by adjusting the conveyance speed to 40 m / min.
(B) Electrodeless UV lamp: Using an “electrodeless UV lamp (H bulb)” manufactured by Fusion UV Systems, with a lamp output of 240 W / cm and a distance of 5 cm from the object to be coated, at a speed of 10 m / min. The coated film was cured by irradiating with an amount of 150 mJ / cm ² for the integrated light quantity.

(Preparation of wooden flooring)
In Example 1, when carrying out the semi-cure of the UV curable composition (coating material) (i) for the top coating, the wooden flooring was applied in the same manner as in Example 1 except that a metal halide lamp was used instead of the high-pressure mercury lamp. I got a product.

(C) Metal halide lamp: Uses a metal halide lamp manufactured by Eye Graphics Co., Ltd., and transports it at a speed of 10 m / min with a distance of 15 cm from the object to be coated at 80 w / cm, and the integrated light quantity becomes 50 mJ / cm ^2. The coating was cured by irradiation in an amount.

(Preparation of wooden flooring)
In Example 1, a wooden floor covering coated product was obtained in the same manner as in Example 1 except that the distance between the electrodeless UV lamp and the object to be coated was changed to 5 cm and changed to 10 cm.

(Preparation of wooden flooring)
In Example 1, paint (ii) was used in place of the paint (i) for top coating, and in the coating of the top paint, a roll coater was used instead of the flow coater. To obtain a wooden floor coating.

(Preparation of wooden flooring)
In Example 1, paint (iii) was used in place of paint (i) for top coating, and in the same manner as Example 1 except that a roll coater was used in place of the flow coater when applying the top paint. To obtain a wooden floor coating.

(Preparation of wooden flooring)
In Example 1, instead of “semi-cure using a high-pressure mercury lamp + non-cured UV lamp (H bulb)” as the curing of the top coat, “semi-curing using a high-pressure mercury lamp + non-electrode UV lamp (D bulb)” A wooden flooring coated product was obtained in the same manner as in Example 1 except that “curing” was performed.
[Comparative Example 1]
(Preparation of wooden flooring)
In Example 1, instead of “curing with a high pressure mercury lamp and semi-curing with an electrodeless UV lamp (H bulb)” instead of “high curing with a high pressure mercury lamp”, semi-curing with a high pressure mercury lamp was not performed. A wooden flooring coated product was obtained in the same manner as in Example 1 except that only the main curing was performed.
[Comparative Example 2]
(Preparation of coating composition)
In the same manner as in Example 1, an ultraviolet curable composition (paint) (i) was prepared.
(Preparation of wooden flooring)
Instead of “semi-cure with high-pressure mercury lamp + non-curing with electrodeless UV lamp (H bulb)” in Example 1, semi-cure with high-pressure mercury lamp is not performed, but “only main curing with high-pressure mercury lamp” is used. A wooden flooring coated product was obtained in the same manner as in Example 1 except that this was performed.
[Comparative Example 3]
(Preparation of wooden flooring)
Instead of “semi-cure with high-pressure mercury lamp + non-curing with electrodeless UV lamp (H bulb)” in Example 5, semi-cure with high-pressure mercury lamp is not performed, and “only main curing with high-pressure mercury lamp” is used. A wooden flooring coated product was obtained in the same manner as in Example 5 except that this was performed.

For the wooden floor coverings obtained in each of the above Examples and Comparative Examples, the gloss, odor, scratch resistance, stain resistance, chemical resistance, and dry crack resistance were evaluated by the following methods. .
The results are shown in Table 1.
<Glossy>
The measurement was performed at an incident angle of 60 degrees in accordance with the method for measuring the specular gloss of JIS-K-5600. Judgment criteria are as follows.

Evaluation 3: 30 or less, passed.
Evaluation 2: 31-70, disqualified.
Evaluation 1: 71 or more, rejected.
<Odor>
Wrapped in 3 layers with a commercially available aluminum foil immediately after painting (within 3 minutes after painting), and then packed in 3 layers with a commercially available polyvinylidene chloride film. Leave at room temperature for 24 hours.

Then, after unpacking and curing at 23 ° C. for 1 hour, it was collected by FLEC, and the photopolymerization initiator and decomposition products causing odor were quantitatively measured by gas chromatography and evaluated in three stages.
The evaluation criteria are as follows.

Evaluation 3: 0 to 1000 μg / m ³ , passed.
Evaluation 2: 1001-10000 μg / m ³ , unacceptable.
Evaluation 1: 10001 μg / m ³ or more, rejected.
<Curing property>
The curability of the wooden floor coating material was evaluated with a three-stage evaluation by toluene rubbing (50 reciprocations at 1 kg load) and the change in the state of the coating film.

The evaluation criteria are as follows.
Evaluation 3: No change in coating film. Pass.
Evaluation 2: The coating film is slightly affected by toluene rubbing. failure.

Evaluation 1: The coating film dissolves in toluene. failure.
<Abrasion resistance>
The rubbing was reciprocated 10 times with a load of 200 g using steel wool # 0000, and the evaluation was made in three stages according to the state of the coating film.

The evaluation criteria are as follows.
Evaluation 3: No change in coating film. Pass.
Evaluation 2: Slight scratches remain on the coating film. failure.

Evaluation 1: Significant scratches remain on the coating film. failure.
<Contamination resistance (1)>
A two-component hair dyeing solution (manufactured by Vigen Co., Ltd., “Hair Color 7G”) is mixed, and the obtained hair dyeing solution is dropped into a circular shape having a diameter of 2 cm. A three-level evaluation is made based on the degree of

The evaluation criteria are as follows.
Evaluation 3: There is no change in the coating film, or some staining is observed. Pass.
Evaluation 2: Dyeing is clearly observed in the coating film. failure.

Evaluation 1: Remarkable dyeing is observed in the coating film. failure.
<Contamination resistance (2)>
A blue ink is put on a watch glass, a spot test is performed for 24 hours, and the floor is evaluated in three stages according to the degree of the trace.

The evaluation criteria are as follows.
Evaluation 3: There is no change in the coating film, or some staining is observed. Pass.
Evaluation 2: Dyeing is clearly observed in the coating film. failure.

Evaluation 1: Remarkable dyeing is observed in the coating film. failure.
<Chemical resistance>
A 5% acetic acid aqueous solution and a 1% caustic soda aqueous solution are placed in a watch glass, and a spot test is performed for 24 hours.

The evaluation criteria are as follows.
Evaluation 3: There is no change in the coating film, or some trace is recognized. Pass.
Evaluation 2: Traces are clearly observed in the coating film. failure.

Evaluation 1: Remarkable traces are observed in the coating film. failure.
<Dry-cracking resistance>
Repeated cold heat test (the coated product is kept at 80 ° C. for 2 hours and then kept at −20 ° C. for 2 hours) 5 times, and the total crack length of the generated surface is measured. Assess sex.

The evaluation criteria are as follows.
Evaluation 3: The crack length is 100 mm or less per 15 cm × 15 cm of the coated product. Pass.
Evaluation 2: Crack length of 101 mm to 500 mm per coated product 15 cm × 15 cm. failure.

  Evaluation 1: The crack length is 501 mm or more per 15 cm × 15 cm of the coated product. failure.

FIG. 1 shows a wavelength of 200 to 500 nm for various “electrodeless UV lamps (model number: H, H plus, D, V, Q, M)” manufactured by “Fusion UV systems JAPAN KK” used in the present invention. It is a figure which shows the relative output (w / 10nm) of the emission spectrum in a range. FIG. 2 shows the relative output (w / 10 nm) or relative intensity (ratio) of the emission spectrum in the wavelength range of 200 to 500 nm for the “high pressure mercury lamp” manufactured by iGraphics and used in the present invention, model number: H06-L31. It is a figure which shows energy,%). In the figure, the solid line indicates the standard type, and the dotted line indicates the ozone-less type. FIG. 3 shows the relative output (w / 10 nm) or relative intensity (ratio) of the emission spectrum in the wavelength range of 200 to 500 nm for the “metal halide lamp” manufactured by Eye Graphics Co., Ltd., model number: M06-L31W. It is a figure which shows energy,%). In the figure, the solid line indicates the standard type, and the dotted line indicates the ozone-less type.

Claims (18)

On the wooden substrate
(A) a photocurable resin;
(B) a photopolymerization initiator;
(C) A photocurable composition comprising a photocurable coating composition containing an extender pigment, semi-cured with a high-pressure mercury lamp or metal halide lamp, and then completely cured with an electrodeless UV lamp. A method for curing a coating film comprising a coating composition.   The photocurable resin (A) is at least one photocurable resin selected from the group consisting of an acrylic resin having a photopolymerizable (meth) acryloyl group, urethane acrylate, epoxy acrylate, and polyester acrylate. A method for curing a coating film comprising the photocurable coating composition according to claim 1.   The photopolymerization initiator (B) is a photopolymerization initiator selected from the group consisting of benzophenones, anthraquinones, thioxanthones, acetophenones, acylphosphine oxides, and methylphenylglyoxyesters. A method for curing a coating film comprising the photocurable coating composition according to claim 1. The extender pigment (C) is silica (SiO ₂ ), talc [Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ ], precipitated barium sulfate (BaSO ₄ ), barium carbonate (BaCO ₃ ), calcium carbonate (CaCO ₃ ). ), Alumina white (Al ₂ (OH) ₃ ), precipitated magnesium carbonate [MgCO ₃ .3Mg (OH) ₂ .H ₂ O], polyethylene wax, one or more selected from the group consisting of bead pigments The method for curing a coating film comprising the photocurable coating composition according to any one of claims 1 to 3, wherein the pigment is a white pigment.   Use photopolymerization initiator (B) in the range of 1-15 parts by weight and extender pigment (C) in the range of 1-30 parts by weight with respect to 100 parts by weight of the photocurable resin (A). A method for curing a coating film comprising the photocurable coating composition according to claim 1.   On the wooden substrate, any one or more of a sealer coating, an undercoat coating, and an intermediate coating are formed in that order in advance, and on the outermost coating of those coatings, The photocurable coating composition is applied, semi-cured with a high-pressure mercury lamp or a metal halide lamp, and then completely cured with an electrodeless UV lamp. A method for curing a coating film comprising the photocurable coating composition.   Irradiation of the electrodeless UV lamp for complete curing is a woody material in which one or two or more electrodeless lamps are arranged on a conveyor at a predetermined distance and the photocurable coating composition is applied. The method for curing a coating film comprising the photocurable coating composition according to any one of claims 1 to 6, wherein the substrate is conveyed on a conveyor at a speed of 1 to 150 m / min. An electrodeless UV lamp having an output of 24 to 240 W / cm per one is irradiated to a wooden substrate coated with the photocurable coating composition in an amount such that the integrated light quantity is 100 to 3000 mJ / cm ² ; The method for curing a coating film comprising a photocurable coating composition according to any one of claims 1 to 7, wherein a semi-cured coating film comprising the photocurable coating composition is completely cured.   Any one or more of a sealer coating, an undercoating coating, and an intermediate coating coating are applied in that order in advance on the wooden substrate, and irradiation with a high-pressure mercury lamp or a metal halide lamp is performed. Applying the above photo-curable coating composition on the outermost layer of the coating, semi-curing it with a high-pressure mercury lamp or metal halide lamp, and then completely curing it with an electrodeless UV lamp A method for curing a coating film comprising the photocurable coating composition according to any one of claims 1 to 8. On the wooden substrate
(A) a photocurable resin;
(B) a photopolymerization initiator;
(C) A photocurable composition comprising a photocurable coating composition containing an extender pigment, semi-cured with a high-pressure mercury lamp or metal halide lamp, and then completely cured with an electrodeless UV lamp. A method for producing a coating film comprising a coating composition. The photocurable resin (A) is at least one photocurable resin selected from the group consisting of an acrylic resin having a photopolymerizable (meth) acryloyl group, urethane acrylate, epoxy acrylate, and polyester acrylate. The manufacturing method of the coating film which consists of a photocurable coating composition of Claim 10 characterized by the above-mentioned. The photopolymerization initiator (B) is a photopolymerization initiator selected from the group consisting of benzophenones, anthraquinones, thioxanthones, acetophenones, acylphosphine oxides, and methylphenylglyoxyesters. The manufacturing method of the coating film which consists of a photocurable coating composition of Claim 10 or 11 . The extender pigment (C) is silica (SiO ₂ ), talc [Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ ], precipitated barium sulfate (BaSO ₄ ), barium carbonate (BaCO ₃ ), calcium carbonate (CaCO ₃ ). ), Alumina white (Al ₂ (OH) ₃ ), precipitated magnesium carbonate [MgCO ₃ .3Mg (OH) ₂ .H ₂ O], polyethylene wax, one or more selected from the group consisting of bead pigments method for producing a coating film made of the photocurable coating composition according to any one of claims 10 to 12, characterized in that a white pigment. Use photopolymerization initiator (B) in the range of 1 to 15 parts by weight and extender pigment (C) in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the photocurable resin (A). coating method for producing a made of a light curable coating composition according to any one of claims 10 to 13, wherein. On the wooden substrate, any one or more of a sealer coating, an undercoat coating, and an intermediate coating are formed in that order in advance, and on the outermost coating of those coatings, coating the photocurable coating composition, after then semi-cured (semi-cured) at a high pressure mercury lamp or a metal halide lamp, characterized in that to fully cure in electrodeless UV lamp, according to any of claims 10-14 The manufacturing method of the coating film which consists of photocurable coating composition of this. Irradiation of the electrodeless UV lamp for complete curing is a woody material in which one or two or more electrodeless lamps are arranged on a conveyor at a predetermined distance and the photocurable coating composition is applied. The method for producing a coating film comprising the photocurable coating composition according to any one of claims 10 to 15 , wherein the substrate is conveyed on a conveyor at a speed of 1 to 150 m / min. An electrodeless UV lamp having an output of 24 to 240 W / cm per one is irradiated to a wooden substrate coated with the photocurable coating composition in an amount such that the integrated light quantity is 100 to 3000 mJ / cm ² ; The method for producing a coating film comprising a photocurable coating composition according to any one of claims 10 to 16, wherein a semi-cured coating film comprising the photocurable coating composition is completely cured. Any one or more of a sealer coating, an undercoating coating, and an intermediate coating coating are applied in that order in advance on the wooden substrate, and irradiation with a high-pressure mercury lamp or a metal halide lamp is performed. Applying the above photo-curable coating composition on the outermost layer of the coating, semi-curing it with a high-pressure mercury lamp or metal halide lamp, and then completely curing it with an electrodeless UV lamp method for producing a coating film made of the photocurable coating composition according to any one of claims 10 to 17, wherein.

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