JP7418803B2 - Coated product manufacturing method and coated board materials - Google Patents

Description

The present invention relates to a method for manufacturing a coated article and a coated plate material.

Recently, highly decorative painted objects (building materials, decorative boards, etc.) have been manufactured by using resin compositions (paints) containing matting agents to provide both high-gloss and low-gloss areas on the surface of the base material. It is being considered to do so.
Such painted objects tend to be perceived in the market as having a more luxurious feel than painted objects with uniform gloss. That is, a coated article in which both a high-gloss area and a low-gloss area are provided on the surface of the base material tends to have high commercial value.

An example of a coated product in which both a high-gloss portion and a low-gloss portion are provided on the surface of the base material is the decorative material described in Patent Document 1.
Patent Document 1 describes a decorative material in which at least a surface coating layer and a partially provided surface printing layer are laminated in this order on a heat-resistant substrate. In this cosmetic material, the surface coat layer is formed of a resin composition containing a fluororesin and a matting agent to have a thickness of 5 μm or more. The surface gloss value of the surface coating layer (incident light angle 60°) is 10 or less, and the surface gloss value (incident light angle 60°) of the surface printing layer is the gloss value of the surface of the surface coating layer. (incident light angle of 60°) by 10 or more.

International Publication No. 2016/159036

In Patent Document 1, a decorative material having both a high gloss portion and a low gloss portion is manufactured by “double coating” of a surface coating layer and a surface printing layer.
However, for "two coats", it is naturally necessary to prepare two types of paints (resin compositions). Also, applying the coat twice makes the work more complicated. In other words, providing both high-gloss areas and low-gloss areas by applying two coats increases manufacturing costs.

As an alternative to double-coating, a method of obtaining a painted object with both high-gloss and low-gloss areas is to apply a paint containing a matting agent unevenly to the substrate using a spray gun. I can think of something. However, when using a spray gun, it is necessary to provide a dedicated booth to prevent paint from scattering. Furthermore, in painting using a spray gun, it is difficult to maintain constant painting conditions, and there is a problem in that it is difficult to produce large quantities of the same product. In other words, using a spray gun to provide both high-gloss areas and low-gloss areas also poses a problem in terms of cost.

On the other hand, as a low-cost coating method, coating using a roll coater or a flow coater is known. However, in painting using a normal roll coater or flow coater, it is theoretically difficult to provide both a high-gloss area and a low-gloss area on one base material. This is because when a roll coater or a flow coater is used, the surface of the base material is basically coated uniformly.

The present invention has been made in view of these circumstances. One of the objects of the present invention is to provide a method for producing a coated article that allows both high-gloss and low-gloss areas to be provided on one base material without requiring complicated processes such as double coating. It is to be.

The present inventors completed the invention provided below and solved the above problems.

According to the invention,
A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
A method for manufacturing a coated article is provided, wherein the light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light.

Further, according to the present invention,
A painted board material, wherein at least a part of the surface of the board material is provided with a coating film formed using a coating composition containing a polymerizable monomer, a photopolymerization initiator, and a matting agent,
The coating film has a high gloss portion and a low gloss portion, and the difference between the 60° gloss value of the high gloss portion and the 60° gloss value of the low gloss portion is 5 or more,
A coated substrate is provided, wherein the absolute value of the difference between the thickness of the high-gloss portion of the coating film and the thickness of the low-gloss portion of the coating film is 4 μm or less.

According to the present invention, there is provided a method for producing a coated article that can provide both a high-gloss area and a low-gloss area on one base material without requiring complicated steps such as double coating.

FIG. 3 is a schematic diagram for explaining a film forming process. FIG. 3 is a diagram schematically showing a method of non-uniformly irradiating an uncured film with light in the first light irradiation step of the first embodiment. It is a figure which shows typically the second light irradiation process of 1st embodiment. It is a figure which shows typically the first light irradiation process of 2nd embodiment. It is a figure for explaining the "first shielding plate" in an Example. It is a figure for explaining the "second shielding plate" in an Example. FIG. 3 is a diagram showing a change in 60° gloss value of the surface of the obtained painted object (wooden building material) in some examples.

Embodiments of the present invention will be described in detail below with reference to the drawings.
In all the drawings, similar components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
To avoid complication, (i) if there are multiple identical components in the same drawing, only one of them will be given a reference numeral and not all of them, or (ii) especially 2 and subsequent parts, components similar to those in FIG. 1 may not be labeled again.
All drawings are for illustrative purposes only. The shapes and dimensional ratios of each member in the drawings do not necessarily correspond to the actual product.

In the present specification, the notation "X to Y" in the description of numerical ranges refers to not less than X and not more than Y, unless otherwise specified. For example, "1 to 5% by mass" means "1 to 5% by mass".

In the description of a group (atomic group) in this specification, a description that does not indicate whether it is substituted or unsubstituted includes both those without a substituent and those with a substituent. For example, the term "alkyl group" includes not only an alkyl group without a substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
In this specification, the expression "(meth)acrylic" represents a concept that includes both acrylic and methacrylic. The same applies to similar expressions such as "(meth)acrylate".

<Method for manufacturing painted objects>
The method for manufacturing a coated article according to this embodiment is as follows:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
A light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including.
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light.

According to the method for producing a coated article according to the present embodiment, a coated article including a coating film having a high-gloss portion and a low-gloss portion can be manufactured. This mechanism can be explained as follows. For clarity, the scope of the present invention is not limited by the following description.

The coating composition used in this embodiment contains a polymerizable monomer that has a relatively low molecular weight of 500 or less and is easily volatile. When an uncured film is formed using a coating composition containing such a polymerizable monomer and the uncured film is cured by irradiating light, the polymerizable monomer is absorbed by the heat from the light source and/or the heat generated by the curing reaction. A part of it ``volatilizes''. Then, the matting agent becomes more likely to be exposed on the film surface by the amount of the volatilized polymerizable monomer.
Therefore, due to the first light irradiation step in which the uncured film is irradiated with light non-uniformly, the degree of exposure of the matting agent on the film surface differs between areas where the amount of exposure was high and areas where the amount of exposure was low. Become. As a result, both a high-gloss area and a low-gloss area can be provided on one base material without applying two coats or the like.
Incidentally, for example, in the examples described below, the smaller the molecular weight of the polymerizable monomer, the larger the difference in gloss. From this, it is reasonable to think that the difference in gloss appears due to "volatilization" of a part of the monomer (because compounds with smaller molecular weights tend to volatilize more easily).

Furthermore, apart from (or together with) the mechanism of developing gloss difference due to the above-mentioned "volatilization of polymerizable monomer", the following mechanism of developing gloss difference is also considered.
When an uncured film is non-uniformly irradiated with light, areas irradiated with strong light will be cured quickly, and areas irradiated with weak light will be cured slowly. Therefore, there is a difference in the "degree of sedimentation" of the matting agent in the film, and a difference occurs in the amount of the matting agent exposed on the coating film surface. It is also believed that this causes a difference in gloss.

To be sure, each of the "high gloss area" and the "low gloss area" is usually an area with a certain degree of "size" and "extension". For example, each area is high gloss/low gloss when measured with micro-tri-gloss (manufactured by BYK) (measurement spot size: 9 mm x 15 mm), which is the device used to measure 60° gloss in the examples. It has a size that can be measured to be glossy. In other words, if two non-overlapping areas (9 mm x 15 mm in size) of the paint film on the final paint job are measured and there is a significant difference in the 60° gloss values, then the paint film is high gloss. It can be said that it has an area and a low gloss area.

In a coated article having a coating film having a high-gloss portion and a low-gloss portion, which is obtained by the method for producing a coated article of the present embodiment, the value of the 60° gloss of the high-gloss portion and the value of the 60° gloss of the low-gloss portion are The difference in values is, for example, 5 or more, preferably 5 to 40%, more preferably 10 to 35%. Appropriately large differences in gloss further increase the commercial value of painted objects.
The value of 60° gloss can be measured using, for example, micro-tri-gloss (manufactured by BYK). Please also refer to JIS Z 8741 regarding the measurement of gloss.

Hereinafter, more specific forms of the method for manufacturing a coated article of this embodiment will be shown as a first embodiment and a second embodiment.

<First embodiment>
The method for manufacturing a coated article according to the first embodiment is as follows:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step in which the uncured film is irradiated with light from a light source to form a coating film;
including;
The light irradiation process includes a first light irradiation process and a second light irradiation process.

In the first embodiment, the first light irradiation step is a step of non-uniformly irradiating the uncured film with light. Immediately after the first light irradiation step, at least a portion of the uncured film is in the state of a partially cured film that is not completely cured. The second light irradiation step is a step in which the partially cured film is irradiated with light to completely cure the entire partially cured film.

Each of the above steps will be explained below.

(Film formation process)
In the film forming step, a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent is applied onto a substrate to form an uncured film.

Details of the components contained in the coating composition will be described later.

The shape and material of the substrate are not particularly limited as long as the coating composition can be applied thereto.
From the viewpoint of industrial productivity and application to building materials, decorative materials, etc., the base material is preferably a plate material. Also, when considering the application of roll coating, flow coating, etc., which will be described later, it is preferable that the substrate is plate-shaped and can be passed between a pair of opposing rolls. That is, the base material is preferably a typically square or rectangular plate material.

When the base material is a plate material, the thickness of the plate material itself (total thickness) is not particularly limited. For example, when the plate material includes wood, the thickness of the plate material is preferably 2 mm or more, more preferably 5 mm or more. The thickness of the plate material itself is, for example, 20 mm or less, more preferably 12 mm or less, from the viewpoint of industrial productivity and application.

Although the material of the base material may be arbitrary, the base material preferably includes wood. More preferably, the base material is a wooden board.
When the base material includes wood as a material, the base material is, for example, decorative plywood. Decorative plywood is usually a plate-shaped material in which a surface layer material is attached to the surface (at least one side) of plywood as a base material. The surface material is also called a decorative board. Wood surface materials are also called veneers, sawn boards, etc. depending on the manufacturing method. Further, the surface material (decorative board) may be paper or a synthetic resin sheet, which will be described later.
As another example, the board material may be natural wood (solid wood) or the like instead of decorative plywood.

When the base material is plywood, the layer below the surface material (base material layer) may be sliced wood or a material formed by mixing wood flour and adhesive (medium-density fiberboard). ) may also be used. Note that plywood manufactured using medium density fiberboard is generally called MDF plywood. These are often used in building materials, such as flooring materials.
Examples of the wood for the surface layer include walnut, cherry, oak, birch, beech, maple, ash, teak, sycamore, falcata, pine, cedar, cypress, eucalyptus, and Japanese walnut.
The thickness of the surface layer material is usually 0.1 to 12 mm, preferably 0.2 to 5 mm.
In particular, decorative plywood with a relatively thin surface layer, specifically decorative plywood with a surface layer thickness of 0.15 to 0.4 mm, is usually positioned as a general-purpose product with a lack of luxury. . As a result of the thinness of the surface layer material, there are few differences in the grain of the wood itself from the surface of the decorative plywood to the deeper parts (color differences due to conduits, resin, pots, bark, etc.), and the shade of color is poor. However, according to the method for producing a coated article of the present embodiment, even if the surface layer material is thin, it is possible to provide a glossy shade with a luxurious feel by coating. In other words, decorative plywood with high commercial value can be manufactured.

As another example, the substrate may include paper. Specifically, when the base material is a board material, the surface (surface layer material) of the board material may be paper.
More specifically, the surface of the base material (board material) may be what is known as printed paper (also referred to as printed sheet, decorative board paper, base paper for decorative sheets, etc.) or olefin printed sheet. good. Printed paper is, for example, paper that has been printed with wood grain, etc., and is sometimes used by pasting it on natural wood or MDF plywood.

There are various types of printing paper, including those made essentially of paper pulp, those with resin added to the base paper, those impregnated with resin during or after papermaking, and those made with titanium oxide or other materials to increase opacity. There are various types, including those to which fired clay is added. Any of these can be used in this embodiment. Specific examples of printed paper include those described in JP 2003-027392, JP 2006-183218, JP 2014-159650, and JP 2015-059292. Examples include, but are not limited to, those described in publications.

From the viewpoint of increasing the "difference" between the high gloss area and the low gloss area, it is preferable that the permeability of the paint into the base material (board material) is low. Although it depends on the permeability of the paint itself, especially when the surface of the base material (board material) is paper, it is preferable to select paper that is difficult for the paint to penetrate in order to prevent excessive penetration of the paint. Examples of paper with low paint permeability include paper in which resin is added to the base paper, paper impregnated with resin during or after papermaking, and the like.

The surface of the base material may be pretreated.
For example, if the substrate is plywood or natural wood, its surface may be polished with sandpaper. Examples of sandpaper that can be used include 320 to 400 grit sandpaper.

Pretreatment may also include forming an undercoat layer or intermediate coat layer with any paint other than a matte paint. Specifically, an undercoat layer or an intermediate coat layer can be provided by a known method using any known or commercially available paint.
To be sure, the "pretreatment" may be performed by a person different from the person who performs the film forming step. That is, as an example, a base material that has already been polished or a base material that has already been provided with an undercoat layer or an intermediate coat layer may be purchased, and the film forming process and subsequent processes may be performed on the base material.

In the film forming step, the coating amount of the coating composition is, for example, 2 to 220 g/m ² , preferably 4 to 110 g/m ² . By applying an appropriate amount of the paint composition, it is easy to provide a sufficient difference in gloss.

Application of the coating composition onto the substrate can be performed by any method/apparatus. Preferably, the film forming step is performed by roll coating, flow coating (also called curtain coating) or spraying. These methods are industrially easy to form a uniform film on a substrate. Therefore, it is preferably applied to the film forming process.

The film forming process by roll coating will be explained with reference to FIG.
In FIG. 1, a feed roll 11A and a coating roll 11B are arranged facing each other and spaced apart from each other at an appropriate interval corresponding to the thickness of the base material 1. This interval is preferably smaller than the thickness of the base material 1 by about 0.50 to 3.00 mm. By adjusting the interval in this way, the base material 1 can be pressed appropriately.
A doctor roll 11C is attached to the circumferential surface of the coating roll 11B.
These rolls can each rotate in the directions indicated by the arrows.
The feed roll 11A and the doctor roll 11C are usually made of iron. The surfaces of these rolls are preferably polished smoothly.
The coating roll 11B is usually made of an iron core with rubber wrapped around the surface. Of course, materials other than rubber (for example, sponge) may be used. Further, the surface of the feed roll 11A may be made of rubber.

A coating composition (coating composition 12) containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent is temporarily stored in the meeting area of the coating roll 11B and doctor roll 11C that are in sliding contact with each other. ing. The coating composition 12 is supplied at appropriate times by suitable means (not shown).

The feed roll 11A, coating roll 11B, and doctor roll 11C are rotated in the directions shown in FIG. Then, the base material 1 is moved in the direction of the arrow in FIG. 1 (from left to right) while being held between the feed roll 11A and the coating roll 11B. Thereby, the coating composition 12 is applied to the surface of the base material 1. At this time, the coating composition 12 is applied to the base material 1 in a pressed state due to the clamping force between the feed roll 11A and the coating roll 11B.
Incidentally, the doctor roll 11C does not normally come into direct contact with the base material 1.

The preferred materials for the base material 1 are as described above.

(Light irradiation process: first light irradiation process)
In the first light irradiation step, the uncured film formed in the film forming step is non-uniformly irradiated with light. Immediately after the first light irradiation step, at least a portion of the uncured film is in the state of a partially cured film (semi-cured film) that is not completely cured. In other words, at least a portion of the uncured film has been cured by being irradiated with light, but a certain amount of unreacted polymerizable monomer remains and is further hardened by additional light irradiation. is in a state of progress. Furthermore, a partially cured film (semi-cured film) usually has poorer organic solvent resistance than a fully cured film.

As mentioned above, it is believed that the degree of surface exposure of the matting agent changes depending on the location due to non-uniform light irradiation, and it is possible to provide both high-gloss areas and low-gloss areas on one substrate surface.

The specific method of non-uniformly irradiating the uncured film formed in the film forming step with light is not particularly limited, but may be a method as shown in FIGS. 2A, 2B, and 2C, for example.

In FIG. 2A, the uncured film is irradiated with light non-uniformly by providing a shield 21 (which can also be called a kind of photomask) between the light source 22 and the base material 1 on which the uncured film is placed. FIG. Moreover, FIG. 2B is a cross-sectional view when FIG. 2A is cut along the cross-section X.
In FIGS. 2A and 2B, the light source 22 is, for example, a rod-shaped high-pressure mercury lamp that emits ultraviolet rays. If there is no shield 21, it is possible to uniformly irradiate light at least in the width direction of the base material 1.
Although only one light source 22 is depicted in FIGS. 2A and 2B, multiple light sources 22 may be used as long as non-uniform exposure is possible.

The surface of the base material 1 is irradiated with light from the light source 22 while the base material 1 is transported in the direction of the arrow by an appropriate transport means (not shown). Light that is not blocked by the shield 21 reaches the surface of the base material 1 . In other words, due to the presence of the shield 21, the uncured film on the base material 1 is exposed non-uniformly. Finally, by going through the second light irradiation step, it is possible to obtain a high-gloss portion and a low-gloss portion that reflect the shape of the shielding object 21 (the shape and size of the shielding portion and the opening, etc.).

As long as a high gloss portion and a low gloss portion are ultimately provided on one base material, the shape of the shield 21 (shape, size, etc. of the shield portion and opening) is not particularly limited. The shape of the shield 21 may be appropriately designed depending on the shapes of the high-gloss portion and low-gloss portion to be obtained.

As long as a high-gloss area and a low-gloss area are ultimately provided on one base material, the distance L ₁ between the light source 22 and the surface of the base material 1 (uncured film), and the distance L between the shield 21 and the base material 1 ₂ etc. are not particularly limited. However, by adjusting these distances, the optical image is appropriately "blurred" due to light diffraction effects, and a continuous natural gradation can be obtained between the high-gloss and low-gloss areas. From this point of view, L ₁ is preferably 2 to 40 cm, more preferably 3 to 30 cm. Further, L ₂ is preferably 1 to 20 cm, more preferably 2 to 10 cm.

FIG. 2C schematically shows a method of non-uniformly irradiating the uncured film with light, using a method different from those shown in FIGS. 2A and 2B.
In FIG. 2C, a light source 22 (point light source) that is sufficiently smaller than the base material 1 is installed at a location sufficiently close to the base material 1. The uncured film is exposed non-uniformly by exposing the substrate 1 to light from the light source 22 while conveying the substrate 1 in the direction of the arrow by a suitable conveyance means (not shown). This non-uniform exposure results in (eventually) high gloss and low gloss areas.
The point light source can be, for example, a metal halide lamp, a UV-LED lamp, etc.

(Light irradiation process: second light irradiation process)
In the second light irradiation step, the partially cured film obtained in the first light irradiation step is irradiated with light to completely cure the entire film.
The second light irradiation step can be performed, for example, by irradiating the entire partially cured film on the base material 1 with light from the light source 22 directly (without intervening a shield), as shown in FIG. .
The specific aspect of the light source 22 is the same as that in FIG. 2A. Although not shown, in the second light irradiation step, the partially cured film may be irradiated with light using a plurality of (for example, 2 to 10) light sources. By doing so, it is easy to irradiate the partially cured film with light over the entire surface and uniformly. Moreover, the process can be shortened.

(Supplementary information regarding the first light irradiation process and the second light irradiation process)
By adjusting the exposure amount in each of the first light irradiation step and the second light irradiation step, a coated object with a more preferable design can be obtained.
Specifically, when the light irradiation amount of the part that is irradiated with the most light in the entire light irradiation process is set to D, the light irradiation amount of the part that is irradiated with the most light in the first light irradiation process is 0. It is preferably 01D to 0.4D, more preferably 0.02D to 0.35D, even more preferably 0.03D to 0.3D.
In the first light irradiation step, the amount of light irradiation at the part that is most irradiated with light is 0.01D or more, so that the polymerizable monomer is sufficiently volatilized and the matting agent is easily exposed to the film surface. It is considered to be.
In the first light irradiation step, by setting the light irradiation amount at the most irradiated part to 0.4D or less, curing of the outermost surface of the uncured film is moderately suppressed, and a sufficient amount of polymerizable monomer is absorbed. It is believed that the matting agent is likely to volatilize and be sufficiently exposed to the film surface.

As another point of view, if the area irradiated with light is rubbed with a cloth moistened with ethyl acetate (10 times with a load of 1 kg) after the first light irradiation step and before the second light irradiation step, Preferably, the membrane dissolves or is attacked. In the first light irradiation step, by keeping the curing to such an extent that the coating film is dissolved or eroded by rubbing, it is possible to further increase the difference in gloss between the high gloss area and the low gloss area.

The total exposure amount in the first light irradiation step and the second light irradiation step is, for example, 150 to 800 mJ/cm ² , preferably 300 to 600 mJ/cm ² . Of course, this exposure amount may be adjusted as appropriate depending on the sensitivity, film thickness, etc. of the coating composition used. There is no particular problem as long as a coating film (cured film) is obtained after the second light irradiation step.

Preferably, the time between each step is not excessively long. That is, the time from when the coating composition begins to be applied to the substrate in the film forming step until the time when light starts to be irradiated in the light irradiation step (first light irradiation step) is preferably 60 seconds or less, more preferably 1 to 2 seconds. 50 seconds, more preferably 2 to 40 seconds.
Further, the time from when light starts to be irradiated in the first light irradiation step to when light starts to be irradiated in the second light irradiation step is preferably 180 seconds or less, more preferably 2 to 150 seconds, and even more preferably 3 to 150 seconds. It is 120 seconds. By not leaving too much time between the first light irradiation step and the second light irradiation step, volatilization of the polymerizable monomer from the portions not irradiated with light can be suppressed. Therefore, it is easier to increase the difference in gloss between the low gloss area and the high gloss area.

(About paint composition)
As mentioned above, in the first embodiment, a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent is used. The components contained in this coating composition will be explained below.

- Polymerizable monomer The polymerizable monomer is not particularly limited as long as it includes one having a molecular weight of 500 or less. The molecular weight of the polymerizable monomer is preferably 400 or less, more preferably 300 or less, even more preferably 270 or less. By using a monomer with a smaller molecular weight, it is easier to increase the difference in gloss between the low gloss area and the high gloss area. Incidentally, the molecular weight of the polymerizable monomer is usually 70 or more.
As long as a low gloss area and a high gloss area can be provided, the polymerizable monomer may include a monomer with a molecular weight of more than 500 in addition to a monomer with a molecular weight of 500 or less. From the viewpoint of the balance between the gloss difference between the low-gloss region and the high-gloss region and the physical properties of the coating film, preferably 50 to 90% by mass, more preferably 60 to 80% by mass of the entire polymerizable monomer has a molecular weight of 500 or less. It is preferable that the monomer is

Apart from the molecular weight, the polymerizable monomer preferably includes a monofunctional monomer and/or a bifunctional monomer. It is thought that because the number of functional groups of the polymerizable monomer is not so large, volatilization is moderately prioritized over crosslinking, and as a result, the difference in gloss between the low gloss area and the high gloss area can be made larger.
From the viewpoint of particularly increasing the difference in gloss between the low-gloss region and the high-gloss region, the polymerizable monomer more preferably contains a monofunctional monomer.

Apart from the number of functional groups, the boiling point of the polymerizable monomer is preferably 400°C or lower, more preferably 300°C or lower. It is thought that by using a polymerizable monomer having a boiling point of 300° C. or less, the polymerizable monomer becomes more easily volatilized during the first light irradiation step. It is considered that the difference in gloss between the low gloss area and the high gloss area can be further increased.
The boiling point of the polymerizable monomer is usually 70°C or higher.

In addition to the boiling point, the polymerizable monomer preferably does not have any polar functional groups other than the polymerizable group. More specifically, the polymerizable monomer preferably does not have a polar functional group such as a hydroxy group or a carboxy group. It is thought that by using a polymerizable monomer that does not have a polar functional group other than a polymerizable group, the polymerizable monomer becomes more easily volatilized during the first light irradiation step.

The polymerizable monomer preferably includes a (meth)acrylate monomer in view of easy availability and appropriate polymerizability. More preferably, the polymerizable monomer is a monofunctional or polyfunctional (meth)acrylate monomer.

Examples of monofunctional (meth)acrylate monomers (compounds having only one polymerizable carbon-carbon double bond in one molecule) include methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate. Acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, phenyl (meth)acrylate Acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, di-n-propyl (meth)acrylamide, dibutyl (meth)acrylamide, (meth)acryloylmorpholine, ( Examples include tetrahydrofurfuryl meth)acrylate, diacetone acrylamide, and ethoxy-diethylene glycol acrylate.

Examples of polyfunctional monomers (compounds having two or more, preferably 2 to 6 polymerizable carbon-carbon double bonds in one molecule) include triethylene glycol di(meth)acrylate and tetraethylene glycol di(meth)acrylate. Acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate , 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, PO adduct di(meth)acrylate of bisphenol A, neopentyl hydroxypivalate Bifunctional monomers such as glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, hydroxyethyl(meth)acrylate, benzyl(meth)acrylate, and phenoxyethyl(meth)acrylate can be mentioned.

In addition, as polyfunctional monomers, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, EO-modified pentaerythritol tetra( meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxytri(meth)acrylate, caprolactone modified trimethylolpropane tri(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, Examples include caprolactam-modified dipentaerythritol hexa(meth)acrylate.

The polymerizable monomer may include urethane (meth)acrylate. Urethane (meth)acrylate is a compound having one or more urethane bonds and one or more (meth)acryloyl groups. The urethane (meth)acrylate preferably has a plurality of (meth)acryloyl groups (that is, the urethane (meth)acrylate is preferably polyfunctional).
As the urethane (meth)acrylate, for example, those sold by Daicel Allnex under the trade name "EBECRYL" series can be used. It is also available from Shin-Nakamura Chemical Industry Co., Ltd., Toagosei Co., Ltd., and others.

The coating composition may contain only one kind of polymerizable monomer, or may contain two or more kinds of polymerizable monomers.
By using two or more types of polymerizable monomers together, it is also possible to appropriately adjust the curability when irradiated with light, the flexibility of the coating film after curing, etc. From the viewpoint of combined use, for example, it is possible to use a polyfunctional monomer and a monofunctional monomer together. It is thought that by doing this, the concentration of carbon-carbon double bonds in the paint can be adjusted appropriately, and the flexibility of the cured film can be made appropriate.
Another possibility is to use urethane (meth)acrylate and a polymerizable monomer other than urethane (meth)acrylate together. Since urethane (meth)acrylate has a flexible skeleton derived from urethane bonds, it is thought that the flexibility of the coating film can be appropriately controlled by using it in combination with other polymerizable monomers.

The amount of polymerizable monomer in the coating composition can be changed as appropriate depending on desired curability and the like. By way of example only, the amount of polymerizable monomer in the coating composition is preferably 10 to 99% by mass, more preferably 20 to 98% by mass, based on all components other than the volatile organic solvent.

-Resin The coating composition may also contain a resin. The resin is used for forming a coating film, improving adhesion of the coating film, and the like. The resin is not particularly limited, and examples include (meth)acrylic resin, urethane (meth)acrylate resin, melamine resin, polyester resin, alkyd resin, silicone resin, fluororesin, epoxy resin, oxetane resin, vinyl chloride resin, polyurethane resin, etc. can be mentioned.
When the resin is a copolymer, its aspect may be random, block, graft, etc.

The weight average molecular weight (Mw) of the resin is preferably 800 to 50,000, more preferably 900 to 40,000. By setting the molecular weight within this range, it becomes easy to obtain a composition having a suitable viscosity and good applicability. In addition, the performance as a coating film (adhesion and water resistance) can be further improved.
The number average molecular weight Mn and the weight average molecular weight Mw can be measured in terms of standard polystyrene by gel permeation chromatography (GPC).

When the coating composition contains a resin, its content is preferably 5% by mass or more, more preferably 10% by mass or more, based on the total amount of nonvolatile components in the coating composition. On the other hand, when the coating composition contains a resin, its content is preferably 90% by mass or less, more preferably 80% by mass or less, based on the total amount of nonvolatile components in the coating composition. This amount is appropriately determined based on the handling properties, coating properties, etc. of the paint.

- Photopolymerization initiator The photopolymerization initiator is not particularly limited as long as it is capable of generating an active substance upon irradiation with light (typically ultraviolet irradiation) and polymerizing the above polymerizable monomer.
Specific examples of the photopolymerization initiator include known radical photopolymerization initiators and cationic photopolymerization initiators, and radical photopolymerization initiators are preferred.

Examples of the photoradical polymerization initiator include alkylphenone type, acylphosphine oxide type, intramolecular hydrogen abstraction type, and oxime ester type.
Commercially available photoradical polymerization initiators include IGM Resins B. V. One example is the OMNIRAD (registered trademark) series manufactured by Co., Ltd. In addition, photoinitiators commercially available from BASF Japan Co., Ltd., CHANGZHOU JIURI NEW MATERIALS, etc. can also be used.

The coating composition may contain only one kind of photopolymerization initiator, or may contain two or more kinds of photopolymerization initiators.
The amount of photopolymerization initiator in the coating composition can be changed as appropriate depending on desired curability and the like. By way of example only, the amount of the photopolymerization initiator in the coating composition is preferably 1 to 20% by weight, more preferably 1 to 15% by weight based on all components other than the volatile organic solvent.

- Matting agent The matting agent is not particularly limited as long as it is capable of scattering visible light on the surface of the coating film. As the matting agent, any particles that can be used as a matting agent in the technical field of coatings can be used.

The matting agent can be at least one of organic particles, inorganic particles, metal particles, and the like. The matting agent may or may not be subjected to surface treatment with various treatment agents, coating treatment, dispersion treatment with dispersant, etc.

Although the shape of the matting agent is not particularly limited, it is preferably spherical in consideration of the uniformity of the coating film. The average particle diameter of the matting agent is preferably 1.5 to 20 μm, more preferably 2 to 15 μm. By setting the value within this numerical range, the matting agent can effectively scatter or absorb visible light, thereby enhancing the matting effect.
The average particle size can typically be measured by dynamic light scattering. Specifically, the matting agent was diluted with methanol, and a cumulant analysis (ISO13321) was performed from the light intensity distribution at 25°C using a device "Zetasizer" manufactured by Malvern Instruments Ltd. The value can be taken as the average particle size.

As the matting agent, inorganic fine particles can be preferably used.
Examples of the inorganic fine particles include salts such as silica, glass, mica, zeolite, diatomaceous earth, graphite, clay, talc, and calcium carbonate, metals, and metal oxides. Among these, silica is preferred from the viewpoint of matte performance. Examples of commercially available inorganic particles include the "Silohobic" series and the "Silysia" series manufactured by Fuji Silysia Chemical Co., Ltd.

As the matting agent, organic fine particles may be used. Among organic fine particles, particularly from the viewpoint of matting performance, for example, polyurethane particles, polyethylene particles, polystyrene particles, (meth)acrylic resin particles, polycarbonate particles, benzoguanamine/formaldehyde condensate particles, benzoguanamine/melamine/formaldehyde condensate particles , urea resin particles, wax particles, etc. Commercially available organic fine particles include, for example, the "Art Pearl" series manufactured by Negami Kogyo Co., Ltd.

The coating composition can include one or more matting agents.
The amount of the matting agent in the coating composition (or the total amount when multiple types of matting agents are included) is usually 1 to 50% by mass, preferably 2% by mass, based on the total amount of nonvolatile components in the coating composition. ~45% by weight, more preferably 3~40% by weight. Further, when the coating composition contains a resin, the amount of particles is usually 5 to 150 parts by weight, preferably 10 to 140 parts by weight, and more preferably 20 to 130 parts by weight based on 100 parts by weight of the resin. . By setting the value within this range, it becomes easier to obtain a composition that has the expected performance (matte) of the particles, an appropriate viscosity, and moderate applicability.

- Dispersant The coating composition may also contain a dispersant. Use of a dispersant is preferable in that it facilitates exposure of the matting agent to the surface of the coating film.
Examples of the dispersant include those containing an acid group, those containing an amine structure, and those containing other polar groups. The dispersant may be a low molecular type dispersant or a polymer type dispersant.

Commercially available products can be used as the dispersant. Examples of commercially available dispersants include BYK's "DISPERBYK" series and "BYK" series, TEGO's "DISPERS" series, and Lubrizol's "Solsperse" series.

When the coating composition contains a dispersant, the coating composition may contain only one kind of dispersant, or may contain two or more kinds of dispersants.
When the coating composition contains a dispersant, the amount thereof is usually 0.01 to 10% by mass, when the total nonvolatile components (components other than volatile organic solvents) in the coating composition are 100% by mass, Preferably it is 0.01 to 8% by mass.

-Other components The coating composition may contain any components other than those mentioned above.
As an example, the coating composition may include particles that primarily contribute to coloring, as a separate component from the matting agent. Thereby, it is possible to obtain a colored article (painted article) that has a low gloss area and a high gloss area and is colored. Particles that contribute to coloring include various pigments.
As another example, the coating composition may include antifoaming agents, leveling agents, polymerization inhibitors, waxes, antioxidants, non-reactive polymers, particulate inorganic fillers, silane coupling agents, light stabilizers, ultraviolet absorbers, It may also contain antistatic agents, slip agents, antibacterial agents, solvents (water and/or organic solvents), and the like.

- Manufacturing method of paint composition The paint composition can be manufactured by appropriately mixing the above-mentioned components. The order of mixing the components and the specific method of mixing are not particularly limited. The coating composition can be produced by any method as long as it can form a low gloss area and/or a high gloss area when formed into a coating film.

<Second embodiment>
The method for manufacturing a coated article according to the second embodiment is as follows:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step in which the uncured film is irradiated with light from a light source to form a coating film;
including.
In the second embodiment, the light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light. However, unlike the first embodiment, the light irradiation process does not necessarily include the second light irradiation process.

In the second embodiment, the film forming step can be the same as in the first embodiment. Therefore, further explanation will be omitted.

In the light irradiation step of the second embodiment, by irradiating a certain part of the uncured film formed in the film forming step with relatively strong light and irradiating another part with relatively weak light, The uncured film is irradiated with light non-uniformly.

Specifically, first, as shown in FIG. 4, an opening 21C through which all of the light emitted from the light source 22 passes and a semi-transparent part through which only part of the light emitted from the light source 22 passes. 21D is prepared. By installing the shield 21B between the light source 22 and the base material 1 provided with the uncured film, the uncured film is irradiated with light non-uniformly.

While the base material 1 is transported in the direction of the arrow by an appropriate transport means (not shown), the surface of the base material 1 is irradiated with light from the light source 22 via the shield 21B. By doing so, the portion of the surface of the base material 1 corresponding to the opening 21C is irradiated with a relatively large amount of light per unit time, and a relatively large amount of the polymerizable monomer is volatilized and cured. On the other hand, the portion corresponding to the semi-transparent portion 21D is irradiated with a relatively small amount of light per unit time, and the polymerizable monomer is cured without much volatilization. By irradiating a sufficient amount of light to completely cure the part corresponding to the semi-transparent part 21D, the uncured film is completely cured on the entire surface, and the coating is provided with a low gloss area and a high gloss area. (At this time, at least the portion corresponding to the opening 21C is irradiated with a larger amount of light than the amount of light required for complete curing).

<Painted board>
The coated board material of this embodiment has a coating film formed on at least a portion of the surface of the board material using a coating composition containing a polymerizable monomer, a photopolymerization initiator, and a matting agent.
The coating film has a high gloss area and a low gloss area. The difference between the 60° gloss value of the high gloss portion and the 60° gloss value of the low gloss portion can be 5 or more, preferably 5 to 40, more preferably 10 to 35.
The absolute value of the difference between the thickness of the high-gloss portion of the coating film and the thickness of the low-gloss portion of the coating film is 4 μm or less.

The coated plate material of this embodiment is preferably manufactured by the method described in <Method for manufacturing coated object> above.
The painted board material of this embodiment has a high gloss portion and a low gloss portion, and the difference between the 60° gloss value of the high gloss portion and the 60° gloss value of the low gloss portion is 5% or more. , good design. Incidentally, the 60° gloss value of the high gloss area is preferably 10 to 70%, more preferably 20 to 70%, and the 60° gloss value of the low gloss area is preferably 1 to 65%, more preferably is 5-60%.

In the painted board material of this embodiment, "the absolute value of the difference between the film thickness of the high-gloss part and the film thickness of the low-gloss part is 4 μm or less" means that the high-gloss part and the low-gloss part are "double-coated". This can be said to indicate that the coating was applied "in one coat using the same paint composition (only one type of paint composition)," rather than being applied by the same paint composition.
The absolute value of the difference between the film thickness of the high gloss portion and the film thickness of the low gloss portion is preferably 0 to 4 μm, more preferably 0 to 3 μm, and still more preferably 0 to 2 μm.
Incidentally, it is preferable that "the absolute value of the difference between the film thickness of the high-gloss part and the film thickness of the low-gloss part is 4 μm or less" from the viewpoint of the texture of the painted board material.

The coated board material of this embodiment preferably does not substantially have a dot-like coating pattern with a diameter of 20 to 200 μm caused by the coating composition. This can be said to indicate that the high-gloss portion and/or the low-gloss portion were not provided by spray painting.
The term "dot-like paint pattern" refers not only to perfect circular patterns, but also to any paint pattern that can be viewed with common sense as a circle or an ellipse when viewed under magnification. In addition, regarding the "diameter" of the dot pattern, if the dot pattern can be considered a perfect circle or a circle, the diameter is the diameter, and if the dot pattern can be considered an ellipse, the diameter is the value of (major axis + minor axis) / 2. .

"Substantially free of dot-like paint patterns with a diameter of 20 to 200 μm" means that the number (density) of dot-like paint patterns with a diameter of 20 to 200 μm on the painted surface of the painted board is typically 30. /m ² or less, preferably 10 pieces/m ² or less.
More preferably, the painted board material of this embodiment does not have a dot-like painted pattern.

As explained in <Method for manufacturing coated object>, the material of the coated board material preferably includes wood or paper. Further, the board material is preferably plywood or a board material with printed paper pasted on the surface. Since these have already been explained, further explanation will be omitted.

In the painted plate material of this embodiment, preferably, the high-gloss portion and the low-gloss portion each exist in the form of a band or a stripe. This can be said to indicate that the high-gloss area and/or the low-gloss area were irradiated with light while the base material was "transported" in a certain direction, for example, as shown in FIGS. 2A, 2B, or 4.
Further, the high-gloss portion and the low-gloss portion that exist in the form of bands or stripes preferably exist in parallel to at least one side of the plate material. This also indicates that the base material was irradiated with light while being "transported" in a certain direction.

In the painted plate material of this embodiment, preferably, the 60° gloss value changes continuously (gradation-like) between the high-gloss portion and the low-gloss portion. This is considered to be because the optical image becomes moderately blurred due to the diffraction effect of light in the light irradiation process, as described in relation to FIG. 2A.

The coated board material of this embodiment preferably does not have any traces of scraping of the solidified coating film. As already explained, the coated substrate of this embodiment can be manufactured by non-uniform exposure or the like. It is not necessary to scrape or polish the coating to provide the high gloss and/or low gloss areas.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.
Below, examples of reference forms will be added.
1.
A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The method for producing a coated article, wherein the light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light.
2.
1. The method for manufacturing a coated article according to
The first light irradiation step includes a step of non-uniformly irradiating the uncured film with light by providing a shield between the light source and the uncured film.
3.
1. or 2. The method for manufacturing a coated article according to
Immediately after the first light irradiation step included in the light irradiation step, at least a portion of the uncured film is in a state of a partially cured film that is not completely cured,
The method for manufacturing a coated article, wherein the light irradiation step includes a second light irradiation step of irradiating the partially cured film with light to completely cure the entire part.
4.
2. or 3. The method for manufacturing a coated article according to
The second light irradiation step includes a step of irradiating the entire surface of the partially cured film with light.
5.
1. ~4. A method for producing a coated article according to any one of
When the light irradiation amount of the part that is irradiated with the most light in the entire light irradiation step is D, the light irradiation amount of the part that is irradiated with the most light in the first light irradiation step is 0.01D to 0. .4D method for producing a coated product.
6.
1. ~5. A method for producing a coated article according to any one of
The method for manufacturing a coated article, wherein the film forming step is performed by roll coating, flow coating, or spraying.
7.
1. ~6. A method for producing a coated article according to any one of
The method for producing a coated article, wherein the polymerizable monomer includes a (meth)acrylate monomer.
8.
1. ~7. A method for producing a coated article according to any one of
The method for producing a coated article, wherein the polymerizable monomer includes a monomer having a molecular weight of 300 or less.
9.
1. ~5. A method for producing a coated article according to any one of
The method for producing a coated article, wherein the polymerizable monomer includes a monofunctional monomer and/or a bifunctional monomer.
10.
1. ~9. A method for producing a coated article according to any one of
A method for manufacturing a coated article, wherein the base material is a plate material.
11.
1. ~10. A method for producing a coated article according to any one of
A method for producing a coated article, wherein the base material includes wood or paper.
12.
1. ~11. A method for producing a coated article according to any one of
A method for producing a coated article, wherein the difference between the 60° gloss of the high gloss portion and the 60° gloss of the low gloss portion is 5 or more.
13.
A painted board material, wherein at least a part of the surface of the board material is provided with a coating film formed using a coating composition containing a polymerizable monomer, a photopolymerization initiator, and a matting agent,
The coating film has a high gloss portion and a low gloss portion, and the difference between the 60° gloss value of the high gloss portion and the 60° gloss value of the low gloss portion is 5 or more,
A coated board material, wherein the absolute value of the difference between the thickness of the high-gloss portion of the coating film and the thickness of the low-gloss portion of the coating film is 4 μm or less.
14.
13. The painted board material described in
The high-gloss portion and the low-gloss portion are formed using the same paint composition.
15.
13. or 14. The painted board material described in
The board material is a painted board material containing wood or paper.
16.
13. ~15. The painted board material according to any one of
The board material is a painted board material that is plywood or a board material with printed paper pasted on the surface.
17.
13. The painted board material according to item 16 to 16,
A coated board material having substantially no dot-like coating pattern with a diameter of 20 to 200 μm due to the coating composition.
18.
13. ~17. The painted board material according to any one of
The painted board material, wherein the high gloss portion and the low gloss portion each exist in a band shape or a strip shape.
19.
13. ~18. The painted board material according to any one of
A coated board material in which a 60° gloss value continuously changes between the high-gloss portion and the low-gloss portion.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. It should be noted that the present invention is not limited only to the embodiments.

<Creating the base material>
First, a base plywood with a length of 60 cm x width of 30 cm x total thickness of 1.2 cm and an oak veneer with a thickness of 0.25 mm attached to the surface was prepared.
This substrate plywood was coated with a colored paint (manufactured by Natco, Flora No. 300: urethane dispersion type colored paint) using a roll coater so that the coating amount was 33 g/m ² . Thereafter, it was dried with hot air at 100° C. for 60 seconds to obtain a colored base plywood.

The colored base plywood was coated with an ultraviolet curable coating composition (for undercoat) having the composition shown in Table 1 so that the coating amount was 44 g/m ² . This was irradiated with ultraviolet light (irradiation dose: 100 mJ/cm ² , maximum irradiation intensity: 80 mW/cm ² ) to cure the painted composition. As described above, an undercoat layer was provided.

Thereafter, an ultraviolet curable coating composition (for intermediate coating) having the composition shown in Table 2 was applied to the base plywood provided with the undercoat layer so that the coating amount was 28 g/m ² . This was irradiated with ultraviolet light (irradiation dose: 100 mJ/cm ² , maximum irradiation intensity: 80 mW/cm ² ) to cure the painted composition. In this way, an intermediate coating layer was provided.

Thereafter, the base plywood provided with the intermediate coating layer was polished with No. 320 waterproof paper.
As described above, a base material (a base material to which a coating composition containing a matting agent is applied) was obtained.

<Configuration of the device for performing the first light irradiation process (first light irradiation device)>
As a device (first light irradiation device) for performing the first light irradiation step, a device roughly as shown in FIG. 2A described above was configured. More specifically, it is as follows.
・Light source: A high-pressure mercury lamp with a length of 60 cm and a diameter of 2.5 cm was placed at a height of 30 cm from the surface of the substrate transport conveyor (not shown in Figure 2A), with the long side facing sideways with respect to the direction of movement of the substrate. It was installed in
・Shielding object (shielding plate)
A first shielding plate as shown in FIG. 5 and a second shielding plate as shown in FIG. 6 were manufactured using aluminum plates. The shielding plate was installed at a height of 5 cm from the base material conveyor surface (not shown in FIG. 2A).

<Configuration of the device for performing the second light irradiation process (second light irradiation device)>
As a device for performing the second light irradiation step (second light irradiation device), a device roughly as shown in FIG. 3 described above was configured. However, in order to perform uniform exposure with a sufficient amount of light, multiple light sources were used.
Specifically, five high-pressure mercury lamps with a length of 60 cm and a diameter of 2.5 cm were placed at 60 cm intervals at a height of 20 cm from the surface of the base material transport conveyor (not shown in Figure 3). It was installed so that the long side faced sideways with respect to the direction of travel.

<Configuration of the device (third light irradiation device) for continuously performing the first light irradiation step and the second light irradiation step>
The following equipment is configured as a device (third light irradiation device) to continuously perform the first light irradiation step that performs non-uniform exposure and the second light irradiation step that performs full-surface exposure. did.

Five high-pressure mercury lamps each having a length of 60 cm and a diameter of 2.5 cm were installed so that their long sides were oriented sideways with respect to the traveling direction of the base material (conveying direction of the base material conveyor).
Among these, the first lamp, which was the first one from the substrate input side, was installed at a height of 30 cm from the surface of the substrate transport conveyor so that its longitudinal side was oriented sideways with respect to the direction of substrate movement. In addition, a shielding plate was installed between the first lamp and the surface of the substrate conveyor. The installation conditions for the shielding plate are the same as those for the first light irradiation device.
The second to fifth lamps from the base material input side were installed at a height of 20 cm from the surface of the base material conveyor so that the horizontal distance from the adjacent lamp was 60 cm.

In the Examples and Comparative Examples described below, the amount of irradiation light and the irradiation intensity were adjusted by appropriately adjusting the transport speed of the base material.

<Example 1>
By the following procedure, a coated object (wooden building material) in which high-gloss areas and low-gloss areas exist in the form of bands or stripes was obtained using one type of coating composition.
(1) A coating composition having the composition shown in Table 3 below was applied to the base material obtained above (comprising an undercoat layer and an intermediate coat layer) using a roll coater in an amount of 11 g/m ² The coating was applied to form an uncured film.
(2) The uncured film was cured (not completely cured) using a first light irradiation device. Specifically, using a first light irradiation device equipped with a first shielding plate, the uncured film was irradiated with ultraviolet rays at an irradiation dose of 40 mJ/cm ² and a maximum irradiation intensity of 40 mW/cm ² . As a result, a part of the uncured film was cured (not completely cured) to obtain a partially cured film.
(3) Using a second light irradiation device without a shielding plate, the partially cured film was irradiated with ultraviolet rays under the conditions of an irradiation light amount of 320 mJ/cm ² and a maximum irradiation intensity of 80 mW/cm ² . As a result, the partially cured film was completely cured.

<Examples 2 to 10, 13, 20, Comparative Examples 1 to 8>
A painted object (wooden building material) was prepared in the same manner as in Example 1, except that the formulation of the coating composition, the shielding plate, and/or the light irradiation conditions were changed as described in Tables 3, 4, or 5 below. I got it.

<Example 11>
With the formulation and shielding plate listed in Table 4 below, the height of the lamp from the substrate conveyor surface of the first light irradiation device was changed from 30 cm to 20 cm, and the maximum irradiation intensity was changed to the conditions listed in the table. A wooden building material was produced in the same manner as in Example 1, except for the following.

<Example 12, Example 19>
With the formulation and shielding plate listed in Table 4 below, the height of the lamp from the substrate conveyor surface of the first light irradiation device was changed from 30 cm to 13 cm, and the maximum irradiation intensity was changed to the conditions listed in the table. A coated object (wooden building material) was obtained in the same manner as in Example 1 except for the following.

<Examples 14 to 16>
A coated article (wooden building material) was obtained by changing the light irradiation device to a third UV curing device using the formulation, shielding plate, and irradiation conditions listed in Table 4 below.
For Examples 15 and 16, based on Example 14, the height of the first lamp of the third light irradiation device from the conveyor surface was changed from 30 cm to 20 cm and 13 cm, respectively, and the maximum irradiation intensity was listed in the table. A painted object (wooden building material) was obtained by changing the conditions.

<Example 17>
Example except that the base material was changed to ``a printed paper measuring 60 cm in length x 30 cm in width x 1.2 cm in total thickness with a 0.25 mm thick wood grain printed on the surface.'' Wooden building materials were prepared in the same manner as in 1.

<Example 18>
The high-pressure mercury lamp of the first light irradiation device was replaced with a UV-LED (FireJet, 365 nm, irradiation port 15 cm, manufactured by PHOSEON), and the height from the surface of the substrate conveyor was changed from 30 cm to 5 cm. Further, the irradiation port of the UV-LED was placed horizontally with respect to the direction of movement of the substrate, at the center of the 30 cm wide substrate and 7.5 cm inside from the edge of the substrate.
The coated ^object ( (wooden building materials) were obtained.

Incidentally, when the surface of the coated objects (wooden building materials) obtained in each example was observed under magnification, no dot-like coating pattern with a diameter of 20 to 200 μm due to the coating composition was observed.

The raw materials listed in Tables 3, 4 and 5 below are as follows.
The number of functional groups and molecular weight of the polymerizable monomers are listed in the table below.

(polymerizable monomer, resin)
ACMO (acryloylmorpholine): manufactured by KJ Chemical Co., Ltd. THFA (tetrahydrofurfuryl acrylate): manufactured by Kyoeisha Chemical Co., Ltd. Ethoxy-diethylene glycol acrylate: manufactured by Kyoeisha Chemical Co., Ltd., light acrylate EC-A
Phenoxyethyl acrylate: Light acrylate PO-A manufactured by Kyoeisha Chemical Co., Ltd.
4-t-Butyl cyclohexyl acrylate: TBCHA manufactured by KJ Chemical Co., Ltd. HEMA (2-hydroxyethyl methacrylate): manufactured by Nippon Shokubai Co., Ltd. Neopentyl glycol diacrylate: manufactured by Nippon Kayaku Co., Ltd., KAYARAD NPGDA
1,6-hexanediol diacrylate: manufactured by Daicel Allnex, HDDA
TPGDA (tripropylene glycol diacrylate): manufactured by Daicel Allnex EBECRYL160S (trimethylolpropane ethoxy triacrylate): manufactured by Daicel Allnex AM-90G (methoxypolyethylene glycol #400 acrylate): KRM8200 (urethane manufactured by Shin-Nakamura Chemical Co., Ltd.) Acrylate): Manufactured by Daicel Allnex, resin with weight average molecular weight 1000 (catalog value)

(matting agent)
Silica (Silysia 436): Manufactured by Fuji Silicia Urethane beads (Art Pearl C-600 transparent): Manufactured by Negami Kogyo Acrylic beads (Art Pearl GR-800T): Manufactured by Negami Kogyo

(Photopolymerization initiator)
OMNIRAD 754: IGM Resins B. V. Blend of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-eth oxy]-ethyl ester
OMNIRAD TPO H:IGM Resins B. V. 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide

(dispersant)
BYK-2008: Manufactured by BYK

<Evaluation>
(Measurement of gloss non-uniformity)
The 60° gloss on the surface of the coated objects (wooden building materials) obtained in Examples and Comparative Examples was measured 1 cm each from the edge of the base material in a direction perpendicular to the conveyance direction in the first light irradiation step, for a total of 29 degrees. Point measurements were taken. A micro-tri-gloss (manufactured by BYK) was used as a measuring device.
In each table listed below, the maximum and minimum values of 60° gloss among all measurement points are listed.

The difference between the maximum and minimum gloss values measured by the above method was calculated. Based on the following criteria, it was evaluated that the larger the difference in gloss, the more clearly the gradation was visible and the more preferable it was.
Excellent: Difference of 10 or more (the gloss gradation is clearly visible)
Good: Difference is 5 or more and less than 10 (gloss gradation is visible)
Defective: Difference is less than 5 (gloss gradation is not visible)

For reference, FIG. 7 shows a graph in which the measurement results of Examples 1, 6, 13 and Comparative Example 1 are plotted with the horizontal axis: distance from the substrate edge (unit: cm) and the vertical axis: 60° gloss. Shown below. From the graph, it can be visually understood that in the example, a coating film (cured film) whose gloss changed "continuously" according to the shape of the opening of the shielding object (shielding plate) was obtained. Ru.

(Measurement of film thickness in high-gloss and low-gloss areas)
Among the measurement points in the above-mentioned "Measurement of non-uniformity of gloss", a cross-section of the part showing the minimum gloss value and a cross-section of the part showing the maximum gloss value were cut out, and the film thickness of each part was measured. Measurements were made at three locations (Note) using a microscope VHX-S50 (manufactured by Keyence Corporation), and the average value was calculated. Then, the difference in average film thickness between the part showing the maximum gloss value and the part showing the minimum gloss value was calculated.
(Note: The measurement spot size of the gloss meter used in the measurement of "Measurement of gloss non-uniformity" has a "width" of 9 mm x 15 mm, so the "part showing the minimum gloss value" and "maximum gloss value" It is difficult to pinpoint the "portion showing" to "one point."Therefore, in each of the above-mentioned cross sections, the film thickness was measured at "three points at the center" with a width of 15 mm, and the average value thereof was adopted. )

(Reference evaluation: surface condition of coating film after first light irradiation process)
After the first light irradiation step and before the second light irradiation step, the irradiated area of the coating film was rubbed with a cloth moistened with ethyl acetate (10 reciprocations with a load of 1 kg). The appearance was evaluated as follows.
○: The coating film was dissolved and not sufficiently cured.
Δ: The coating film is slightly attacked.
×: There is no change in the coating film and it is sufficiently cured.

The composition of the coating composition, the base material (surface layer material of plywood), light irradiation conditions, and evaluation results are summarized in the table below.
In the composition of the coating composition, the unit of amount of each component is parts by mass.

As shown in Examples 1 to 20, an uncured film formed from a coating composition containing a polymerizable monomer with a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent was treated by non-uniformly irradiating light, etc. By a relatively simple method, it was possible to produce a coated article having a coating film having a high-gloss area and a low-gloss area. That is, in Examples 1 to 20, it was possible to provide both a high-gloss area and a low-gloss area on one base material without requiring a complicated process such as double coating.
On the other hand, in Comparative Examples 1 to 6 in which light was irradiated uniformly without using a shielding plate during light irradiation, and in Comparative Example 7 in which a paint composition containing no matting agent was used, high gloss areas and low gloss areas It was not possible to obtain a painted object with sufficient differences in gloss between parts.

Analyzing the examples in more detail, the following can be said.
- The difference in gloss tends to be larger when monofunctional monomers, those with small molecular weights, those with small boiling points, etc. are used as polymerizable monomers. This is also shown in the graphs for Examples 1 and 6 in FIG. This can also be understood from the comparison between Examples 1 to 5 and Example 20.
- If the surface condition of the coating film after the first light irradiation step is "○", the gloss difference (maximum gloss value - minimum gloss value) tends to increase. It is suggested that by keeping the degree of curing in the first light irradiation step to a moderate level, the final difference in gloss increases.

1 Base material 11A Feed roll 11B Coating roll 11C Doctor roll 12 Paint composition 21 Shielding object 21B Shielding object 21C Opening section 21D Semi-transparent section 22 Light source 22B Point light source

Claims (26)

A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
Immediately after the first light irradiation step included in the light irradiation step, at least a portion of the uncured film is in a state of a partially cured film that is not completely cured,
The method for manufacturing a coated article, wherein the light irradiation step includes a second light irradiation step of irradiating the partially cured film with light to completely cure the entire part . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
The first light irradiation step includes a step of non-uniformly irradiating the uncured film with light by providing a shield between the light source and the uncured film,
The second light irradiation step includes a step of irradiating the entire surface of the partially cured film with light . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
When the light irradiation amount of the part that is irradiated with the most light in the entire light irradiation step is D, the light irradiation amount of the part that is irradiated with the most light in the first light irradiation step is 0.01D to 0. .4D method for producing a coated product. A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
The method for producing a coated article, wherein the polymerizable monomer includes a (meth)acrylate monomer . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
A method for producing a coated article , wherein the difference between the 60° gloss of the high gloss portion and the 60° gloss of the low gloss portion is 5 or more . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
A method for producing a coated article, wherein the amount of the polymerizable monomer having a molecular weight of 500 or less in the coating composition is 20 to 98% by mass based on all components other than the volatile organic solvent . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The light irradiation step includes a first light irradiation step of non-uniformly irradiating the uncured film with light,
The method for producing a coated article, wherein the polymerizable monomer includes a polyfunctional monomer . A method for producing a painted object comprising a coating film having a high gloss portion and a low gloss portion, the method comprising:
A film forming step of forming an uncured film by applying a coating composition containing a polymerizable monomer having a molecular weight of 500 or less, a photopolymerization initiator, and a matting agent onto a substrate;
a light irradiation step of irradiating the uncured film with light from a light source to form a coating film;
including;
The method for manufacturing a coated article, wherein the light irradiation step includes a first light irradiation step of non-uniformly irradiating the exposed uncured film with light. The method for producing a coated article according to any one of claims 1 and 3 to 8 ,
The first light irradiation step includes a step of non-uniformly irradiating the uncured film with light by providing a shield between the light source and the uncured film. The method for producing a coated article according to any one of claims 2 to 8 ,
Immediately after the first light irradiation step included in the light irradiation step, at least a portion of the uncured film is in a state of a partially cured film that is not completely cured,
The method for manufacturing a coated article, wherein the light irradiation step includes a second light irradiation step of irradiating the partially cured film with light to completely cure the entire part. The method for manufacturing a coated article according to claim 1 or 8 ,
The second light irradiation step includes a step of irradiating the entire surface of the partially cured film with light. The method for producing a coated article according to any one of claims 1 , 2 and 4 to 8, comprising:
When the light irradiation amount of the part that is irradiated with the most light in the entire light irradiation step is D, the light irradiation amount of the part that is irradiated with the most light in the first light irradiation step is 0.01D to 0. .4D method for producing a coated product. A method for producing a coated article according to any one of claims 1 to 12 , comprising:
The method for manufacturing a coated article, wherein the film forming step is performed by roll coating, flow coating, or spraying. The method for producing a coated article according to any one of claims 1 to 3 and 5 to 8 ,
The method for producing a coated article, wherein the polymerizable monomer includes a (meth)acrylate monomer. A method for producing a coated article according to any one of claims 1 to 14 , comprising:
The method for producing a coated article, wherein the polymerizable monomer includes a monomer having a molecular weight of 300 or less. A method for producing a coated article according to any one of claims 1 to 6 and 8 ,
The method for producing a coated article, wherein the polymerizable monomer includes a monofunctional monomer and/or a bifunctional monomer. A method for producing a coated article according to any one of claims 1 to 16 , comprising:
A method for manufacturing a coated article, wherein the base material is a plate material. A method for producing a coated article according to any one of claims 1 to 17 ,
A method for producing a coated article, wherein the base material includes wood or paper. A method for producing a coated article according to any one of claims 1 to 4 and 6 to 8 ,
A method for producing a coated article, wherein the difference between the 60° gloss of the high gloss portion and the 60° gloss of the low gloss portion is 5 or more. A painted board material, wherein at least a part of the surface of the board material is provided with a coating film formed using a coating composition containing a polymerizable monomer, a photopolymerization initiator, and a matting agent,
The coating film has a high gloss portion and a low gloss portion, and the difference between the 60° gloss value of the high gloss portion and the 60° gloss value of the low gloss portion is 5 or more,
A coated board material, wherein the absolute value of the difference between the thickness of the high-gloss portion of the coating film and the thickness of the low-gloss portion of the coating film is 4 μm or less. The painted board material according to claim 20 ,
The high-gloss portion and the low-gloss portion are formed using the same paint composition. The painted board material according to claim 20 or 21 ,
The board material is a painted board material containing wood or paper. The painted board material according to any one of claims 20 to 22 ,
The board material is a painted board material that is plywood or a board material with printed paper pasted on the surface. The painted board material according to claims 20 to 23 ,
A coated board material having substantially no dot-like coating pattern with a diameter of 20 to 200 μm due to the coating composition. The painted board material according to any one of claims 20 to 24 ,
The painted board material, wherein the high gloss portion and the low gloss portion each exist in a band shape or a strip shape. The painted board material according to any one of claims 20 to 25 ,
A coated board material in which a 60° gloss value continuously changes between the high-gloss portion and the low-gloss portion.

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