JP2023027702A - Coating material for wood part, wood part exterior building material, and wood part exterior structure - Google Patents

Abstract

To provide a coating material for a wood part which uses coated wood as an exterior material, and makes appearance change hardly visible even when a film coated and formed onto the wood is peeled.SOLUTION: A coating material for a wood part is coated onto wood part exterior building materials 21 of a wood part exterior structure which includes a heat insulation material 12 installed in the outside of an exterior wall material 11 of a building, a waterproof sheet 13 installed in the outside of the heat insulation material and the wood part exterior building materials 21 installed in the outside of the waterproof sheet 13 through furring strips 14. The coating material for the wood part is a coating material for a wood part containing a synthetic resin as a binding material, and a film coated and formed onto wood has a glossiness holding rate of 5-50% after 500 hours in an accelerated weathering test (xenon lamp method).SELECTED DRAWING: Figure 1

Description

The technical field of the present specification includes wood coatings applied to wood (wood), wood exterior building materials coated with wood coatings, and wood exterior structures using the wood exterior building materials. Regarding.

BACKGROUND ART Conventionally, wood paints are known that are applied to wood in order to use wood as an exterior building material (for example, Patent Documents 1 and 2).

Japanese Patent No. 3524548 JP 2014-101504 A

However, with conventional paints for wood, when the coated wood is used as an exterior material, and the coating (coating film) formed by coating the wood deteriorates over time and partially peels off, the coating is damaged. There is a problem that the peeled portion and the non-peeled portion have different color tones, and the change in appearance is easily visible.

The problem to be solved by the technology of the present specification has been made in view of the above points. To provide a paint for wooden parts in which changes in appearance are hardly visible.

The paint for wood according to the embodiment of the present specification is a paint for wood using a synthetic resin as a binder,
A film formed by coating on wood is characterized by having a gloss retention rate of 5 to 50% after 500 hours of an accelerated weather resistance test (xenon lamp method).

According to the paint for wood according to the embodiment of the present specification, the film formed by applying the paint to wood is inferior in accelerated weathering (light) resistance, so that the wood coated with the paint for wood is in an outdoor environment. Exposure to direct sunlight, wind and rain will prematurely degrade the synthetic resin of the binding material. The coating becomes discontinuous and becomes fine coating pieces due to deterioration of the synthetic resin of the binder by ultraviolet rays. In addition, the discontinuity of the synthetic resin weakens the adhesion to the wood, and the coating gradually peels off in small pieces when exposed to direct sunlight and wind and rain. Since the fine coating pieces are gradually peeled off, it is possible to make it difficult to visually recognize changes in the appearance of the coating formed by painting on wood even when the coating is peeled off.

Here, the paint for wood contains ink,
The light transmittance of a 40 μm thick film formed by coating can be 15 to 45% at a wavelength of 300 to 350 nm and 25 to 55% at a wavelength of 350 to 400 nm.

According to this, the film formed by painting on wood transmits ultraviolet rays. For this reason, the surface layer of the wood coated with the paint for wood is deteriorated by ultraviolet rays. When the wood coated with the paint for wood is exposed to direct sunlight, wind and rain in an outdoor environment, the surface of the wood deteriorated by ultraviolet rays becomes substantially gray. In addition, since the paint for wood contains black ink, the wood coated with the paint for wood exhibits a substantially gray color similar to the color of the surface of wood deteriorated by ultraviolet rays. Since the color of the portion coated with the paint for wood is similar to the color of the surface of the deteriorated wood, it is possible to make it difficult to visually recognize the change in appearance when the fine coating pieces are gradually peeled off.

Further, in the paint for wooden parts, the synthetic resin may be a vinyl-modified epoxy ester resin.

According to this, it is possible to quickly degrade the coating formed by applying the paint for wood to the wood.

Here, the wooden exterior building material according to the embodiment is coated with a film formed from a wood paint containing ink and a synthetic resin, and is made of wood for outdoor use exposed to direct sunlight and wind and rain. A wooden exterior building material with
The coating is characterized in that it transmits ultraviolet rays and gradually peels off when exposed to direct sunlight and wind and rain.

According to the wooden exterior building material according to the embodiment, since the film transmits ultraviolet rays, the surface layer of the wood deteriorates with ultraviolet rays. When the wood coated with the paint for wood is exposed to direct sunlight, wind and rain in an outdoor environment, the surface of the wood deteriorated by ultraviolet rays becomes substantially gray. In addition, since the film contains black ink, the wood coated with the film exhibits a substantially gray color similar to the color of the surface of the wood that has been degraded by ultraviolet rays. Since the film is gradually peeled off by exposure to direct sunlight and wind and rain, it is possible to make it difficult to visually recognize changes in the exterior appearance of the wood exterior building material even when the film is peeled off.

In addition, the wooden exterior building material according to the embodiment may be coated with a film formed from the above paint for wood.

According to this, fine coating pieces are gradually exfoliated by exposure to direct sunlight and wind and rain, so that changes in appearance can be made difficult to be visually recognized.

In addition, the wooden exterior structure according to the embodiment includes a heat insulating material installed outside the exterior wall material of a building, a waterproof sheet installed outside the heat insulating material, and the above-mentioned waterproof sheet installed outside the waterproof sheet. and a wooden exterior building material.

According to this, it is possible to provide a wooden exterior structure in which the external wall of the building is provided with a wooden exterior building material in which a change in appearance is less likely to be visually recognized.

According to the paint for wood of the present specification, the coating formed by coating on wood gradually peels off in small coating pieces when exposed to direct sunlight and wind and rain. Since the fine coating pieces are gradually peeled off, it is possible to make it difficult to visually recognize changes in the appearance of the coating formed by painting on wood even when the coating is peeled off.

(A) is a diagram showing the configuration of a wooden exterior structure provided with wooden exterior building materials coated with the wood paint of the embodiment, and (B) is a cross section taken along line IB-IB in FIG. 1 (A). It is a diagram.

Hereinafter, a wood coating, a wood exterior building material, and a wood exterior structure according to embodiments of the present specification will be described. In addition, the scope of the present invention is not limited to the scope disclosed in the embodiments. As shown in FIG. 1, the wooden exterior structure according to the embodiment includes a heat insulating material 12 installed outside an exterior wall material 11 of a building, a waterproof sheet 13 installed outside the heat insulating material, and a waterproof sheet 13 and a wooden exterior building material 21 installed via furring strips 14 on the outside of. As a result, the wooden exterior structure can be a fireproof structure stipulated in Article 2, Item 8 of the Building Standards Law. The wooden exterior building material 21 is obtained by coating wood with the paint for wood according to the embodiment, and forming a film 22 made of the paint for wood on the surface of the wood.

Here, the notation of color in this specification is as follows.

Substantially gray means that the absolute values of a ^* and b ^* are respectively 50 or less when the color is represented by CIELAB (L ^* a ^* b ^* ). In another embodiment, the absolute values of a ^* and b ^* can each be 30 or less, and in yet another embodiment, the absolute values of a ^* and b ^* can each be 20 or less.

An approximate color is a color that approximates a certain color, and when a color is represented by CIELAB (L ^* a ^* b ^* ), the color difference between two colors (ΔE ^* =[(ΔL ^* ) ² + (Δa ^* ) ² +(Δb ^* ) ² ] ^1/2 ) is 20 or less. In another embodiment, the color difference (ΔE ^* ) can be 10 or less, and in yet another embodiment, the color difference (ΔE ^* ) can be 5 or less.

In addition, the gloss retention rate after 500 hours of accelerated weather resistance test (xenon lamp method) in this specification is "JIS K 5600-7-7: 2008 General test method for paint-Part 7: Long-term durability of coating film- Section 7: Accelerated Weatherability and Accelerated Lightfastness (Xenon Lamp Method), Method 1, Cycle A, relative humidity during drying: 50±5%, 300-400 nm irradiance: 60 W/m ² , Black panel temperature: 63 ± 2 ° C, gloss retention when tested for 500 hours (Method 1: Matching the spectral distribution of horizontal surface all-sky radiation in the ultraviolet and visible regions (used for weather resistance test ), Cycle A: Wetting time 18 minutes, drying time 102 minutes, relative humidity 40-60% during drying, irradiance continuous operation).

The paint for wood contains synthetic resin as a raw material, and if necessary, ink, mica, silica, a dispersant, an antifoaming agent, an antiseptic, and an antifreezing agent. A paint for wood can be produced by mixing these raw materials using a mixer such as a dissolver mixer.

The synthetic resin used in the paint for wood of the embodiment has a gloss retention rate of 5 to 50% after 500 hours of an accelerated weather resistance test (xenon lamp method) in the film 22 formed by painting on wood. and is a synthetic resin with poor weather resistance. Since the weather resistance of the film 22 formed by painting on wood is poor, the wood coated with the paint for wood is exposed to direct sunlight, wind and rain in an outdoor environment, and the synthetic resin of the binding material quickly deteriorates. is degraded by ultraviolet rays and reduced in molecular weight. By reducing the molecular weight of the synthetic resin of the binding material, the coating 22 becomes discontinuous and becomes fine coating pieces, and adhesion to the wood is weakened. Gradually exfoliate piece by piece. Since the fine coating pieces are gradually peeled off, it is possible to make it difficult to visually recognize any change in the appearance of the coating formed on wood even when the coating is peeled off.

As such a synthetic resin, in the embodiment, an acrylic resin having a weight average molecular weight of 100,000 or less, a vinyl-modified epoxy ester resin, polyvinyl alcohol, or the like can be used. The synthetic resin used in the paint for wood according to the embodiment can be used as it is as long as it is liquid, or it can be used in the form of being emulsified (synthetic resin emulsion), dispersed, or dissolved in water. It can also be used in the form of being dispersed or dissolved in a solvent.

In another embodiment, the synthetic resin used in the wood coating can be a vinyl modified epoxy ester resin. The coating 22, which is formed from a paint for wood using a vinyl-modified epoxy ester resin as a binding material, has adhesiveness and can maintain adhesion to the wood due to the adhesiveness. It does not peel off immediately, but has an excellent effect of gradually peeling off. The adhesion of the coating 22 formed from the paint for wood according to the embodiment can be 2B or less in scratch hardness (pencil method) (JIS K 5600-5-4:1999). In another embodiment, the scratch hardness can be 4B or less, and in yet another embodiment 6B or less. The weight average molecular weight of the vinyl-modified epoxy ester resin of the embodiment can be 1,000 to 200,000. This is because the coating 22 formed from the paint for wood can be degraded by ultraviolet light at an early stage. As another embodiment, the weight average molecular weight of the vinyl-modified epoxy ester resin can be 10,000 to 100,000.

A vinyl-modified epoxy ester resin can be obtained by a polymerization reaction between a condensate obtained by an addition reaction of an epoxy resin and a fatty acid and a mixture of a vinyl compound. Further, the vinyl-modified epoxy ester resin is unsaturated fatty acid-modified epoxy ester resin (A1), the following general formula (I)

(n is 1 to 10, and R ¹ is an alkylene group having 2 to 18 carbon atoms.)
A vinyl-modified epoxy ester resin (A2) obtained by bulk polymerization of a vinyl monomer (a1) having a terminal carboxyl group-containing structure represented by and another vinyl monomer (a2), a basic compound, and water is used to neutralize some or all of the carboxyl groups contained in the vinyl-modified epoxy ester resin (A2) with a basic compound (N,N-dimethylaminoethanol), and the vinyl modification obtained by this neutralization It can be obtained by dispersing the neutralized epoxy ester resin (A3) in water.

Commercially available vinyl-modified epoxy ester resins can also be used. Commercially available vinyl-modified epoxy ester resins include Modepics (manufactured by Arakawa Chemical Co., Ltd.), Lipoxy (manufactured by Showa Denko K.K.), Barnock (manufactured by DIC Corporation), and Haripol (manufactured by Harima Kasei Co., Ltd.). can.

In the paint for wood of the embodiment, the coating 22 having a thickness of 40 μm formed by coating has a light transmittance of 15 to 45% at a wavelength of 300 to 350 nm and 25 to 55% at a wavelength of 350 to 400 nm. be. As a result, the coating 22 formed by coating the wood will transmit ultraviolet rays. For this reason, the surface layer of the wood coated with the paint for wood is deteriorated by ultraviolet rays. When the wood coated with the paint for wood is exposed to direct sunlight, wind and rain in an outdoor environment, the surface of the wood deteriorated by ultraviolet rays becomes substantially gray.

The black ink imparts a substantially gray color to the coating 22 formed from the paint for wood, and simulates the grayed color of the wood until it is turned to gray. For this reason, the wood to which the paint for wood is applied can be used even if it is a solid wood that has not been ashed. Become. Since the film 22 formed by coating the wood transmits ultraviolet rays, the surface layer of the wood coated with the wood paint gradually deteriorates (ashes) and gradually takes on an almost gray color. The color of the painted part and the color of the surface of the deteriorated wood are similar to each other. That is, the color difference before and after deterioration is small. Therefore, when the fine coating pieces of the coating 22 formed by coating the wood are gradually peeled off, the color of the portion where the coating 22 remains is similar to the color of the peeled portion, and the appearance change is visually recognized. can be made difficult to
Japanese ink such as pine soot ink and oil soot ink can be used as the ink of the embodiment. In addition, sumi ink contains soot and animal glue.

Pine smoke as soot is created by burning pine trees and their resin, and by using pine soot ink, the size of the soot particles can be made uneven, resulting in a heavy black to blue-gray color. You can have a wide range of colors up to. On the other hand, oil soot is made by burning vegetable oil, and by using oil soot ink, the soot particles can be made fine and uniform, and the color can be glossy and deep, and ink can be used as ink. When used in the form of, soot aggregation can be suppressed. As another embodiment, oil soot ink can be used.

Nikawa is a gelatinous substance obtained as a jelly-like substance when the skins and bones of animals such as cows and horses are boiled and cooled. Glue has the role of adjusting the shape of the ink, and the role of giving the liquid when the ink is grated an appropriate amount of stickiness. Japanese ink can contain fragrances such as dragon brain and musk. This is because the fragrance can soften the odor of glue.

The ink can be used in the form of India ink, which is easy to handle. India ink can contain calcium chloride. This is because the inclusion of calcium chloride stabilizes the soot colloid in India ink and facilitates the penetration of soot into the grain of the wood when the paint for wood is applied to the wood. Examples of commercially available oil smoke ink ink include: Shogei Kuretake Shikon, Shogei Kuretake Pure Black, Shogei Kuretake Blue, Dark Ink Shogei Kuretake, Super Dark Ink Shogei Kuretake, Shogei Kuretake Shikon Extreme made by Kuretake) etc. can be used. As a commercially available pine soot ink, for example, pure pine soot ink liquid Matsujun Kai (manufactured by Kuretake Co., Ltd.) can be used. The non-volatile content of Indian ink can be 15 to 35% by mass. Also, the ink particle size can be 0.01 to 1 μm.

The mica of the embodiment is obtained by coating a thin plate-like silicate mineral (mica) with a metal oxide such as titanium oxide, and is sometimes called a pearl pigment. By being contained in the paint for wood, mica can impart a pearl-like luster to the coating 22 made of the paint for wood by light interference, thereby emphasizing the luster of ink (sp2 mixture of ink). It is thought to be derived from orbital π bonds.).

Mica also has the effect of making the grain of wood stand out. The wood surface absorbs water differently depending on the wood grain (annual rings), and when the paint for wood is applied to the surface of the wood, the synthetic resin of the paint for wood is absorbed by the wood in areas where the wood has a high water absorption, and mica forms the film 22. The pearl-like luster is emphasized by being oriented on the surface. On the other hand, in the portion where the water absorption is small, the orientation of the mica to the surface of the coating 22 is small, so the pearl-like luster becomes dull.

The particle size of mica can be 10-100 μm. This is because the luster of ink can be emphasized. If the particle size of the mica is less than 10 μm, the gloss may be blurred and the gloss of ink may not be emphasized. On the other hand, if it exceeds 100 μm, the gloss becomes strong and may not be suitable as the gloss of black ink. In another embodiment, the mica particle size can be 10-60 μm.

Silica is a raw material added to lower the gloss of the coating 22 made of paint for wood. The particle size of silica in embodiments can be 1 to 10 μm. This is because the gloss of the coating 22 can be preferably lowered. If the particle size of silica is less than 1 μm, it may not be possible to uniformly disperse it in the paint for wood. On the other hand, if it exceeds 10 μm, there is a possibility that the gloss of the coating 22 cannot be lowered appropriately. As another embodiment, the particle size of silica can be 2-5 μm. In addition, silica whose surface is hydrophilic can be used. Fine gaps are generated at the interface between silica and synthetic resin in the coating 22, making the coating 22 more likely to absorb water, and repeated rainfall and drying causes the coating 22 to repeatedly expand and contract, causing the coating 22 to move away from the wood surface. This is because it becomes possible to peel off gradually.

Dispersants, antifoaming agents, preservatives, and antifreeze agents can be appropriately selected from commercially available products and added in appropriate amounts as necessary.

Table 1 shows a blending example of the paint for wood according to the embodiment and a preferable range (parts by mass) of other raw materials when the synthetic resin emulsion is 100 (parts by mass).

The paint for wood according to the embodiment can be applied using a roller, a brush, or the like. The coating amount is 30 to 50 g/m ² in terms of non-volatile matter, and the film thickness is 30 to 50 μm.

The wood to which the paint for wood of the embodiment is applied is a flat plate having a thickness, and the ratio of the length in the transverse direction to the thickness of the flat plate (length in the transverse direction/thickness) is 2 to 10. can be done. This is because warping of wood over a long period of time can be suppressed. As another embodiment, the width-to-thickness ratio of the flat plate can be 4-8.

The wooden exterior structure according to the embodiment includes a heat insulating material 12 installed outside an exterior wall material 11 of a building, a waterproof sheet 13 installed outside the insulating material, and furrings 14 outside the waterproof sheet 13. and a wooden exterior building material 21 installed via. The wood exterior building material 21 is a wood coated with the wood paint of the embodiment and provided with a film 22 on the surface.

Exterior wall material 11 of the embodiment is not particularly limited, but includes, for example, plywood, MDF (medium density fiberboard), OSB (oriented strand board), gypsum board, calcium silicate board, particle board, and the like. can be used.

The heat insulating material 12 of the embodiment is not particularly limited, but mineral fiber heat insulating material, wood fiber heat insulating material, foamed plastic heat insulating material can be used. These can be used by appropriately selecting commercially available products. As another embodiment, a foamed plastic heat insulating material having excellent heat insulating properties can be used, and as still another embodiment, a phenolic foam heat insulating material, which is a foamed plastic heat insulating material, can be used. The thickness of the phenolic foam insulation can be 50-200 mm. This is because the wooden exterior structure can be a fireproof structure stipulated in Article 2, Item 8 of the Building Standards Law.

The waterproof sheet 13 of the embodiment is not particularly limited, but a waterproof sheet having moisture permeability can be used. This is because dew condensation on the wooden exterior structure can be suppressed by providing moisture permeability. The waterproof sheet 13 can contain an ultraviolet absorber to enhance the weather resistance of the waterproof sheet 13 . The waterproof sheet 13 can be coated with moisture-permeable paint.

The moisture-permeable paint contains, as raw materials, a synthetic resin emulsion, colloidal silica, and, if necessary, a coloring pigment, an extender pigment, a wetting agent, a pH adjuster, and a thickening agent. Table 2 shows a blending example of the moisture-permeable paint and a preferred range (parts by mass) of other raw materials when the synthetic resin emulsion is 100 (parts by mass).

The synthetic resin emulsion is a binding material for the moisture-permeable paint, and urethane resin, acrylic resin, styrene-butadiene copolymer resin, and silicone resin can be used as the composition of the resin. These may be used alone, may be used in combination of two or more, or may be used by copolymerizing different monomers. Colloidal silica is a raw material that enhances the moisture permeability of the coating formed from the moisture-permeable paint. A coloring pigment is a raw material that imparts color to a film, and titanium oxide, carbon black, iron oxide, and the like can be used. Extender pigments form a film together with a binder, and calcium carbonate, silica sand, talc, barium sulfate, and the like can be used.

The moisture-permeable paint of the embodiment is applied in such a thickness that the hiding rate (hiding power (for pale color paint) (JIS K 5600-4-1:1999)) is 80% or more. This is because even if the moisture-permeable paint does not contain an ultraviolet absorber, the weather resistance can be improved and the moisture permeability of the waterproof sheet 13 is less likely to be lowered. In another embodiment, the hiding rate can be 90% or more, and in another embodiment, 95% or more.

By applying the moisture-permeable paint of the embodiment with a coating thickness that provides a concealment rate of 80% or more, the coating thickness can enhance waterproofness. The waterproof sheet 13 can be omitted from the wooden exterior structure by enhancing the waterproofness of the film formed from the moisture-permeable paint. This is because waterproofness is ensured by a film formed from a moisture-permeable paint. At this time, since the moisture-permeable paint is directly applied to the heat insulating material 12, the pH of the moisture-permeable paint is adjusted to 6-8. This is because hydrolysis of the heat insulating material 12 (phenolic foam heat insulating material) can be suppressed.

A wooden exterior building material 21 is installed via a furring strip 14 on a heat insulating material 12 to which a waterproof sheet 13 is affixed and a moisture-permeable paint is applied.

The furring strip 14 is not particularly limited, but a furring strip 14 made of metal, wood, or plastic can be used, and the substrate (film made of moisture-permeable paint) must be flat (less unevenness). ), the furring strip 14 can be omitted.

Next, a construction method for the wooden exterior structure of the embodiment will be described. The paint for wooden parts of the embodiment includes a first step of attaching the heat insulating material 12 to the exterior wall material 11, a second step of attaching the waterproof sheet 13 to the heat insulating material 12, and a second step of applying the moisture permeable paint to the waterproof sheet 13. 3, a fourth step of placing the furring strips 14 on the waterproof sheet 13 coated with moisture-permeable paint, and a fifth step of fixing the wooden exterior building materials 21 to the furring strips 14 .

In the first step of attaching the heat insulating material 12 to the exterior wall material 11, the heat insulating material 12 is attached to the exterior wall material 11 using nails, screws, adhesives, or the like. The joints of the heat insulating material 12 are made airtight by attaching a general-purpose waterproof tape. In the second step of attaching the waterproof sheet 13 to the heat insulating material 12, the waterproof sheet 13 is attached to the heat insulating material 12 using pin tackers, nails, or the like.

The third step of applying the moisture-permeable paint to the waterproof sheet 13 is to apply the moisture-permeable paint to the waterproof sheet 13 using a roller, a brush, or the like. The coating amount is 100 to 150 g/m ² in terms of non-volatile matter. A fourth step of disposing the furring strip 14 on the waterproof sheet 13 coated with the moisture-permeable paint is to attach the furring strip 14 to the insulating material to which the waterproof sheet 13 coated with the moisture-permeable paint is attached using screws or nails. Fixed to 12.

The fifth step of fixing the wooden exterior building material 21 to the furring strip 14 is to fix the wooden exterior building material 21 to the furring strip 14 using screws, nails, and adhesives. The wooden exterior building material 21 can be placed (fixed) by butting even with a blindfold, and can also be provided with tongues or interlocking gables in the butting. The wooden exterior building material 21 can be arranged so that the grain of the wood constituting the wooden exterior building material 21 extends horizontally. This is because it is possible to suppress water absorption from the conduit of the wood.

The wooden exterior structure constructed in this way can be a wooden exterior structure with wooden exterior building materials 21 on the outer wall of the building, and can be used as a fire prevention system stipulated in Article 2, Item 8 of the Building Standards Law. can be a structure.

In the wood exterior building material 21 provided with the coating 22 formed from the wood coating, fine coating pieces are gradually peeled off.

The wood paint of the embodiment is a wood paint with a different formulation, which is applied to the surface of a cedar lumber of 105 mm width × 300 mm length × 12 mm thickness at a coating amount of 150 g / m ² (wet state) and dried. A test body was prepared and evaluated (tested) as described below. Table 3 lists the coating compositions of Examples and Comparative Examples and test results.

Appearance Change Appearance change was evaluated by exposing a test piece to the outdoors for one year and comparing the appearance with a backup test piece (a test piece not exposed to the outdoors). ○ indicates that there is almost no difference between the exposed test specimen and the backup test specimen; was evaluated as ×.

Appearance approximation with unpainted wood after deterioration The appearance approximation with unpainted wood after deterioration was evaluated by exposing the specimens outdoors for one year and comparing the appearance with unpainted cedar lumber exposed under the same conditions. was evaluated. Then, ◎ indicates that the exposed test specimen and unpainted wood are similar in appearance. When the body was further exposed, it was evaluated as Δ, and when the appearance was far from it, it was evaluated as ×.

Details of the raw materials are described below.

Synthetic resin A
Vinyl-modified epoxy ester resin Weight average molecular weight about 50,000 Non-volatile content 60% by mass
Pencil hardness <6B
Synthetic resin B
Urethane-acrylic copolymer resin Weight average molecular weight about 1,000,000 Non-volatile content 50% by mass
Pencil hardness 2H
Metal oxide coated mica particle size 30 μm
Composition Mica 70wt%, Titanium Dioxide 29.5wt%, Silica 0.5wt%
Silica particle size 3.4 μm
ink A
Type Oil soot ink Non-volatile content 19.5% by mass
Ink particle size 0.1 μm
ink B
Type Pine soot ink Non-volatile content 27.8% by mass
Ink particle size 0.1 μm
Dispersants, antifoaming agents, preservatives and antifreeze agents were selected from commercial products and used.

(Example 1)
In Example 1, which is the best mode, synthetic resin A, which is a vinyl-modified epoxy ester resin, is used as the binding material, Indian ink A is used as the ink, and metal oxide-coated mica and silica are added. In the specimens exposed to the outdoors, since the coating 22 transmits ultraviolet rays, the surface layer of the wood coated with the paint for wood deteriorates (ashes) with UV rays and exhibits a substantially gray color. was presenting. Since the coating 22 of the specimen exposed to the outdoors had poor weather resistance, each fine coating piece was peeled off. ) has a color (ΔE ^* =5.0) that is similar to that of ), the peeled portion was hardly visible from the outside, and could be visually recognized as a single color. For this reason, there was almost no difference in appearance between the specimens exposed to the outdoors and the backup specimens. In the test specimens exposed to the outdoors, the metal oxide-coated mica emphasized the gloss of the black ink, and the silica suppressed the gloss of the coating 22. Compared to lumber, the appearance was close.

(Examples 2 and 3)
Example 2 is obtained by increasing the amount of metal oxide-coated mica from Example 1. In Example 3, from Example 1, the amount of metal oxide-coated mica was reduced and the amount of silica was increased. There is almost no difference in appearance between the specimens exposed to the outdoors and the backup specimens, and the appearance is similar to that of the unpainted cedar lumber exposed under the same conditions. rice field.

(Examples 4-6)
In Example 4, the metal oxide-coated mica was removed from Example 1, and the amount of silica was increased. Example 5 is Example 1 with no silica and an increased amount of metal oxide-coated mica. Example 6 is Example 1 without the metal oxide coated mica and silica. There was almost no difference in appearance between the specimens exposed to the outdoors and the backup specimens. In addition, Example 5 had a strong black gloss, and Example 6 had a resinous gloss.

(Example 7)
In Example 7, from Example 1, the amount of synthetic resin was reduced, the compounding amounts of metal oxide-coated mica and silica were adjusted, and a dispersant and an antifoaming agent were added. There was almost no difference in appearance between the specimens exposed to the outdoors and the backup specimens, and the appearance was similar to that of the unpainted cedar lumber exposed under the same conditions.

(Example 8)
In Example 8, from Example 1, the amount of synthetic resin was increased, the ink was changed to Indian ink B, and the compounding amounts of metal oxide-coated mica and silica were adjusted. There was almost no difference in appearance between the specimens exposed to the outdoors and the backup specimens, and the appearance was similar to that of the unpainted cedar lumber exposed under the same conditions.

(Comparative example 1)
In Comparative Example 1, the synthetic resin in Example 1 was changed to a synthetic resin B, which is a urethane-acrylic copolymer resin having excellent weather resistance, and ink was eliminated. The test pieces exposed to the outdoors show little deterioration of the resin, so although wet colors can be seen, there is almost no ultraviolet deterioration (ashing) on the surface of the wood, and it is in a state similar to an unpainted board, which is a difference from the backup test piece. The difference was small, and the difference could be confirmed when they were arranged side by side, but the difference was not noticeable when they were separated. However, when compared with unpainted cedar lumber exposed under the same conditions, the unpainted cedar lumber showed deterioration due to ultraviolet rays (ashing), resulting in a far different appearance.

(Comparative example 2)
Comparative Example 2 is obtained by adding ink to Comparative Example 1. The test pieces exposed to the outdoors show little deterioration of the resin, so although wet colors can be seen, there is almost no ultraviolet deterioration (ashing) on the surface of the wood, and it is in a state similar to an unpainted board, which is a difference from the backup test piece. The difference was small, and the difference could be confirmed when they were arranged side by side, but the difference was not noticeable when they were separated. When compared with unpainted cedar lumber exposed under the same conditions, UV deterioration (ashing) was observed in unpainted cedar lumber. When placed side by side, the difference can be confirmed, but when separated, there is no sense of incongruity.

DESCRIPTION OF SYMBOLS 11... Exterior wall material, 12... Heat insulating material, 13... Waterproof sheet, 14... Furring strip, 21... Wooden part exterior construction material, 22... Coating.

Claims (6)

A paint for wood that uses a synthetic resin as a binder,
1. A paint for wood, characterized in that a coating formed by coating on wood has a gloss retention rate of 5 to 50% after 500 hours of an accelerated weather resistance test (xenon lamp method). contains ink,
2. The tree according to claim 1, wherein the light transmittance of the coated film having a thickness of 40 μm is 15 to 45% at a wavelength of 300 to 350 nm and 25 to 55% at a wavelength of 350 to 400 nm. Part paint. 2. A paint for wood parts according to claim 1, wherein said synthetic resin is a vinyl-modified epoxy ester resin. A wood-based exterior building material for outdoor use exposed to direct sunlight, wind and rain, covered with a film formed from a paint for wood containing black ink and a synthetic resin,
A wooden exterior building material characterized in that said film transmits ultraviolet rays and gradually peels off when exposed to direct sunlight and wind and rain. An exterior building material for wood, characterized by being coated with a film formed from the paint for wood according to claim 1 . A heat insulating material installed on the outside of an exterior wall material of a building, a waterproof sheet installed on the outside of the insulating material, and the wooden exterior building material according to claim 4 or 5 installed on the outside of the waterproof sheet. A wooden exterior structure comprising:

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