Wood paints and wood exterior building materials

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

[Technical Field]

[0001] The technical field of this specification relates to wood paints that are applied to wood (lumber), wood exterior building materials that are coated with wood paints, and wood exterior structures that use wood exterior building materials. [Background technology]

[0002] BACKGROUND ART Paints for wood that are applied to wood for use as exterior building materials have been known (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3524548 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-101504 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional wood paints had the problem that when the painted wood was used as an exterior material and the coating (paint film) formed on the wood deteriorated over time and partially peeled off, the color tone of the peeled and unpeeled areas differed, making the change in appearance easily visible.

[0005] The problem that the technology of this specification aims to solve has been made in consideration of the above points, and its object is to provide a paint for wood that, when painted wood is used as an exterior material, causes little visible change in appearance even if the coating formed by painting the wood peels off. [Means for solving the problem]

[0006] The wood paint according to the embodiment of the present specification is a wood paint using a synthetic resin as a binder, The coating formed by painting on wood is characterized by having a gloss retention rate of 5 to 50% after 500 hours of accelerated weather resistance testing (xenon lamp method).

[0007] According to the wood paints according to the embodiments of the present specification, the coating formed by application to wood has poor accelerated weathering (light) resistance, and therefore when wood coated with the wood paint is exposed to direct sunlight, wind, and rain in an outdoor environment, the synthetic resin binder quickly deteriorates due to ultraviolet light. The coating becomes discontinuous as the synthetic resin binder deteriorates due to ultraviolet light degradation, breaking down into small coating pieces. Furthermore, as the synthetic resin becomes discontinuous, its adhesion to the wood weakens, and the coating gradually peels off in small coating pieces when exposed to direct sunlight, wind, and rain. Because the small coating pieces peel off gradually, the coating formed by application to wood can be made such that even when peeled off, the change in appearance is difficult to visually detect.

[0008] Here, the paint for wood contains ink, The coating formed by coating and having a thickness of 40 μm can have a light transmittance of 15 to 45% at wavelengths of 300 to 350 nm and 25 to 55% at wavelengths of 350 to 400 nm.

[0009] According to this, the coating formed by painting on wood transmits ultraviolet light. Therefore, the surface of wood painted with the wood paint is subject to ultraviolet degradation. When wood painted with the wood paint is exposed to direct sunlight and wind and rain in an outdoor environment, the surface of the wood that has deteriorated due to ultraviolet light assumes a generally gray color. Furthermore, because the wood paint contains ink, the wood painted with the wood paint assumes a generally gray color, a color similar to the color of the surface of wood that has deteriorated due to ultraviolet light. Because the color of the area painted with the wood paint and the color of the surface of the deteriorated wood are similar, changes in appearance can be made difficult to visually recognize when small pieces of the coating gradually peel off.

[0010] In the above wood paint, the synthetic resin may be a vinyl-modified epoxy ester resin.

[0011] This allows the coating film formed by applying the wood paint to the wood to be quickly deteriorated by ultraviolet rays.

[0012] Here, the wooden exterior building material according to the embodiment is a wooden exterior building material made of wood as a base material, which is coated with a coating film formed from a wood paint containing ink and a synthetic resin, and is intended for outdoor use where it is exposed to direct sunlight and wind and rain, The coating is characterized by being transparent to ultraviolet rays and gradually peeling off when exposed to direct sunlight and wind and rain.

[0013] According to the wood exterior building material of the embodiment, the coating transmits ultraviolet rays, so the surface of the wood deteriorates due to ultraviolet rays. When wood coated with a wood paint is exposed to direct sunlight, wind, and rain in an outdoor environment, the surface of the wood deteriorates due to ultraviolet rays and assumes a generally gray color. Furthermore, because the coating contains ink, the wood coated with the coating assumes a generally gray color, a color similar to the color of the surface of wood deteriorated by ultraviolet rays. Because the coating gradually peels off due to exposure to direct sunlight, wind, and rain, the wood exterior building material can be made such that changes in appearance are difficult to visually recognize even if the coating peels off.

[0014] Furthermore, the wood exterior building material according to the embodiment can be coated with a coating film formed from the above-mentioned wood paint.

[0015] This allows the small pieces of coating to gradually peel off when exposed to direct sunlight and wind and rain, making it difficult to visually recognize any changes in appearance.

[0016] In addition, the wooden exterior structure of the embodiment can include an insulating material installed on the outside of the exterior wall material of a building, a waterproof sheet installed on the outside of the insulating material, and the above-mentioned wooden exterior building material installed on the outside of the waterproof sheet.

[0017] This allows the exterior walls of a building to have a wooden exterior structure equipped with wooden exterior building materials that make changes in appearance difficult to see. [Effects of the Invention]

[0018] According to the wood paint of this specification, the coating formed by painting on wood gradually peels off in small pieces when exposed to direct sunlight and wind and rain. Because the small pieces peel off gradually, the coating formed by painting on wood can be made to show a coating that is difficult to visually recognize as having peeled off. [Brief explanation of the drawings]

[0019] [Figure 1] 1A is a diagram showing the configuration of a wooden exterior structure equipped with a wooden exterior building material coated with an embodiment of a wood paint, and FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes wood paints, wood exterior building materials, and wood exterior structures according to embodiments of the present specification. The scope of the present invention is not limited to the scope disclosed in the embodiments. As shown in FIG. 1 , the wood exterior structure according to the embodiment includes an insulating material 12 installed on the outside of a building's exterior wall material 11, a waterproof sheet 13 installed on the outside of the insulating material, and a wood exterior building material 21 installed on the outside of the waterproof sheet 13 via furring strips 14. This allows the wood exterior structure to meet the fire prevention requirements of Article 2, Paragraph 8 of the Building Standards Act. The wood exterior building material 21 is made by applying a wood paint according to the embodiment to wood, forming a coating 22 made of the wood paint on the surface of the wood.

[0021] Here, the colors used in this specification are represented as follows:

[0022] The color gray is the CIELAB (L * a * b * ), a * and b * In another embodiment, the absolute values ​​of a * and b * The absolute values ​​of a and b can be 30 or less, and in another embodiment, * and b* The absolute values ​​of each of the above can be 20 or less.

[0023] An approximate color is a color that is close to a certain color, and the color is expressed in CIELAB (L * a * b * ) the color difference between two colors (ΔE * =[(ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2 ] 1 / 2 ) is 20 or less. * ) can be 10 or less, and in yet another embodiment, the color difference (ΔE * ) can be 5 or less.

[0024] In addition, the gloss retention rate after 500 hours of accelerated weather resistance testing (xenon lamp method) in this specification is determined by "JIS K 5600-7-7:2008 General test methods for paints - Part 7: Long-term durability of coating films - Section 7: Accelerated weather resistance and accelerated light resistance (xenon lamp method)" according to Method 1, Cycle A, with a relative humidity of 50±5% during the drying period and an irradiance of 300 to 400 nm of 60 W / m 2 The gloss retention rate is measured after 500 hours of testing at a black panel temperature of 63±2°C (Method 1: Matching the spectral distribution of horizontal global radiation in the ultraviolet and visible ranges (used for weather resistance testing), Cycle A: Wetting time 18 minutes, drying time 102 minutes, relative humidity 40-60% during the drying period, continuous operation with irradiance).

[0025] Wood paints contain synthetic resins as raw materials, and may optionally contain ink, mica, silica, dispersants, antifoaming agents, preservatives, and antifreeze agents. Wood paints can be produced by mixing these raw materials using a mixer such as a dissolver mixer.

[0026] The synthetic resin used in the wood paint of the embodiment is a synthetic resin with poor weather resistance, in that the coating 22 formed by painting the wood has a gloss retention rate of 5 to 50% after 500 hours in an accelerated weathering test (xenon lamp method). Because the weather resistance of the coating 22 formed by painting the wood is poor, wood coated with the wood paint is exposed to direct sunlight, wind, and rain in an outdoor environment, and the synthetic resin binder quickly deteriorates due to ultraviolet light, resulting in its degradation to smaller molecules. As the synthetic resin binder is degraded to smaller molecules, the coating 22 becomes discontinuous and breaks into small pieces, weakening its adhesion to the wood. When exposed to direct sunlight, wind, and rain, the coating gradually peels off in small pieces. Because the small pieces peel off gradually, the coating formed by painting the wood shows little visible change in appearance, even when peeled off.

[0027] In the embodiment, such synthetic resins include acrylic resins with a weight-average molecular weight of 100,000 or less, vinyl-modified epoxy ester resins, polyvinyl alcohol, etc. If the synthetic resin used in the wood paint of the embodiment is in a liquid form, it can be used as is, or it can be used in a form emulsified (synthetic resin emulsion), dispersed, or dissolved in water, or in a form dispersed or dissolved in a solvent such as an organic solvent.

[0028] In another embodiment, the synthetic resin used in the wood paint can be a vinyl-modified epoxy ester resin. The coating 22 formed from a wood paint using a vinyl-modified epoxy ester resin as a binder has adhesive properties that allow it to maintain adhesion to wood. Therefore, even if the coating breaks into small pieces, it does not immediately peel off, but rather has an excellent effect of gradually peeling them off. The adhesiveness of the coating 22 formed from the wood paint of this embodiment can be such that the scratch hardness (pencil method) (JIS K 5600-5-4:1999) is 2B or less. 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 this embodiment can be 1,000 to 200,000. This is because ultraviolet degradation of the coating 22 formed from the wood paint can be accelerated. In another embodiment, the weight-average molecular weight of the vinyl-modified epoxy ester resin can be 10,000 to 100,000.

[0029] The vinyl-modified epoxy ester resin can be obtained by a polymerization reaction between a condensate obtained by an addition reaction between an epoxy resin and a fatty acid and a mixture of vinyl compounds. ... an unsaturated fatty acid-modified epoxy ester resin (A1), a vinyl ester represented by the following general formula

[0030] [ka]

[0031] (n is 1 to 10, R 1 represents an alkylene group having 2 to 18 carbon atoms. and other vinyl monomers (a2), a basic compound, and water, 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 then disperse the neutralized vinyl-modified epoxy ester resin (A3) obtained by the neutralization in water.

[0032] Commercially available vinyl-modified epoxy ester resins can also be used, such as Modepics (manufactured by Arakawa Chemical Industries, Ltd.), Lipoxy (manufactured by Showa Denko K.K.), Burnock (manufactured by DIC Corporation), and Haripol (manufactured by Harima Chemicals Co., Ltd.).

[0033] The wood paint of this embodiment is applied to form a 40 μm-thick coating 22 with a light transmittance of 15-45% at wavelengths of 300-350 nm and 25-55% at wavelengths of 350-400 nm. This allows ultraviolet light to pass through the coating 22 applied to wood. As a result, the surface of wood coated with the wood paint is subject to ultraviolet degradation. When wood coated with the wood paint is exposed to direct sunlight, wind, and rain in an outdoor environment, the surface of the wood deteriorates due to ultraviolet light and assumes a generally gray color.

[0034] The ink imparts a generally gray color to the coating 22 formed from the wood paint, simulating the ashed color of the wood until it turns to ashed. Therefore, even unashed solid wood can be used as the wood to which the wood paint is applied, and the generally gray color imparted to it approximates the ashed color. Because the coating 22 formed by painting on wood transmits ultraviolet light, the surface layer of the wood coated with the wood paint gradually deteriorates (ashes) and gradually turns a generally gray color, so that the color of the area coated with the wood paint and the color of the surface of the deteriorated wood are similar. In other words, the color difference before and after deterioration is small. Therefore, when small pieces of the coating 22 formed by painting on wood gradually peel off, the color of the remaining area of ​​the coating 22 and the color of the peeled area are similar, making it difficult to visually recognize the change in appearance. In the embodiment, Japanese ink such as pine soot ink or lamp soot ink can be used. Japanese ink contains soot and glue.

[0035] Pine soot is made by burning pine trees and their resin, and by using pine soot ink, the size of the soot particles can be made non-uniform, allowing for a wide range of colors from deep black to blue-gray. On the other hand, lamp soot is made by burning vegetable oil, and by using lamp soot ink, the soot particles can be made fine and uniform, giving the color luster and depth, and also suppressing the aggregation of soot when ink is used in the form of ink juice. In another embodiment, lamp soot ink can be used.

[0036] Nikawa (nikawa) is a gelatinous substance that forms a jelly-like substance when the hide and bones of animals such as cows and horses are boiled and cooled. Nikawa has the role of shaping the ink and giving the ink a suitable viscosity when it is grated. Japanese ink can contain fragrances such as borneol and musk, as these can help to reduce the odor of the glue.

[0037] The ink can be used in the form of ink juice, which is easy to handle. The ink juice can contain calcium chloride. By adding calcium chloride, the soot colloid in the ink can be stabilized and the soot can easily penetrate the wood grain when a wood coating is applied to the wood. Examples of commercially available lamp soot ink juices that can be used include Shogei Kuretake Shikon, Shogei Kuretake Pure Black, Shogei Kuretake Blue, Koinoku Shogei Kuretake, Super Koinoku Shogei Kuretake, and Shogei Kuretake Shikon Kyoku (all manufactured by Kuretake Co., Ltd.). Examples of commercially available pine soot ink juices that can be used include Jun Shoen Grinding Ink Shojun Kai (manufactured by Kuretake Co., Ltd.). The non-volatile content of the ink can be 15 to 35% by mass. The particle size of the ink can be 0.01 to 1 μm.

[0038] The mica in this embodiment is a thin-plate silicate mineral (mica) coated with a metal oxide such as titanium oxide, and is sometimes called a pearl pigment. When contained in a wood paint, mica imparts a pearl-like luster to the coating 22 made of the wood paint due to light interference, thereby emphasizing the luster of the ink (thought to be due to the π bond of the sp2 hybrid orbital of the ink).

[0039] Mica also has the effect of highlighting the wood grain. The water absorption of wood surfaces varies depending on the grain (annual rings), and when wood paint is applied to a wood surface, in areas with high water absorption, the synthetic resin in the wood paint is absorbed into the wood, causing the mica to emerge and be oriented on the surface of the coating 22, enhancing the pearly luster. On the other hand, in areas with low water absorption, the mica is less oriented on the surface of the coating 22, and the pearly luster becomes duller.

[0040] The particle size of the mica can be set to 10 to 100 μm. This is because it can enhance the luster of the ink. If the particle size of the mica is less than 10 μm, the luster may be dull and the luster of the ink may not be enhanced. On the other hand, if the particle size exceeds 100 μm, the luster may be too strong and may not be suitable for the luster of the ink. In another embodiment, the particle size of the mica can be set to 10 to 60 μm.

[0041] Silica is a raw material added to reduce the gloss of the coating 22 made of wood paint. In one embodiment, the particle size of silica can be 1 to 10 μm. This is because the gloss of the coating 22 can be reduced appropriately. If the particle size of silica is less than 1 μm, it may not be possible to uniformly disperse it in the wood paint. On the other hand, if the particle size exceeds 10 μm, it may not be possible to reduce the gloss of the coating 22 appropriately. In another embodiment, the particle size of silica can be 2 to 5 μm. Note that silica with a hydrophilic surface can be used. This is because minute gaps are formed at the interface between the silica and the synthetic resin in the coating 22, making the coating 22 more susceptible to water absorption. Repeated expansion and contraction of the coating 22 due to repeated rainfall and drying can cause the coating 22 to gradually peel off from the wood surface.

[0042] The dispersant, antifoaming agent, preservative, and antifreezing agent can be selected from commercially available products and added in appropriate amounts as needed.

[0043] Table 1 shows an example of a formulation for a wood paint according to an embodiment, and the preferred ranges (parts by mass) of other raw materials when the synthetic resin emulsion is taken as 100 (parts by mass).

[0044] [Table 1]

[0045] The wood paint of the embodiment can be applied using a roller, a brush, etc. The application amount is 30 to 50 g / m2 in terms of non-volatile content. 2 The film thickness is 30 to 50 μm.

[0046] The wood to be coated with the wood paint of the embodiment is a thick flat plate, and the ratio of the short-side length to the thickness of the flat plate (short-side length / thickness) can be 2 to 10. This is because this can prevent the wood from warping over the long term. In another embodiment, the ratio of the short-side length to the thickness of the flat plate can be 4 to 8.

[0047] The wooden exterior structure according to the embodiment comprises a heat insulating material 12 installed on the outside of an exterior wall material 11 of a building, a waterproof sheet 13 installed on the outside of the heat insulating material, and a wooden exterior building material 21 installed on the outside of the waterproof sheet 13 via furring strips 14. The wooden exterior building material 21 is made of wood that has been painted with the wood paint according to the embodiment, and has a coating 22 on its surface.

[0048] The exterior wall material 11 of the embodiment is not particularly limited, but examples that can be used include plywood, MDF (medium density fiberboard), OSB (oriented strand board), gypsum board, calcium silicate board, particle board, etc.

[0049] The insulating material 12 of the embodiment is not particularly limited, but mineral fiber insulating material, wood fiber insulating material, and foam plastic insulating material can be used. These can be commercially available products selected appropriately. In another embodiment, foam plastic insulating material with excellent thermal insulation properties can be used, and in yet another embodiment, phenol foam insulating material, which is a foam plastic insulating material, can be used. The thickness of the phenol foam insulating material can be 50 to 200 mm. This is because the wooden exterior structure can be a fireproof structure as defined in Article 2, Paragraph 8 of the Building Standards Act.

[0050] The waterproof sheet 13 of the embodiment is not particularly limited, but a moisture-permeable waterproof sheet can be used. This is because moisture permeability can suppress condensation on the wooden exterior structure. The waterproof sheet 13 can contain an ultraviolet absorber to improve the weather resistance of the waterproof sheet 13. The waterproof sheet 13 can be painted with a moisture-permeable paint.

[0051] The moisture-permeable paint contains synthetic resin emulsion, colloidal silica, and, if necessary, color pigment, extender pigment, wetting agent, pH adjuster, and thickener as raw materials. Table 2 shows an example of the moisture-permeable paint formulation and the preferred ranges (parts by mass) of other raw materials when the synthetic resin emulsion is taken as 100 parts by mass.

[0052] [Table 2]

[0053] Synthetic resin emulsions are binders for moisture-permeable paints, and resin compositions that can be used include urethane resins, acrylic resins, styrene-butadiene copolymer resins, and silicone resins. These can be used alone, in combination with two or more other materials, or copolymerized with different monomers. Colloidal silica is a raw material that enhances the moisture permeability of the coating formed from the moisture-permeable paint. Coloring pigments are raw materials that impart color to the coating, and examples of such materials include titanium oxide, carbon black, and iron oxide. Extender pigments form a coating together with the binder, and examples of such materials include calcium carbonate, silica sand, talc, and barium sulfate.

[0054] In this embodiment, the moisture-permeable paint is applied at a thickness that provides a hiding rate (hiding power (for light color paints) (JIS K 5600-4-1:1999)) of 80% or more. This is because the moisture-permeable paint can improve weather resistance even without containing an ultraviolet absorber, and does not significantly reduce the moisture permeability of the waterproof sheet 13. In another embodiment, the hiding rate can be 90% or more, and in yet another embodiment, 95% or more.

[0055] The moisture-permeable paint of the embodiment can be applied in a thickness that provides a hiding rate of 80% or more, thereby improving waterproofing. The improved waterproofing of the coating formed from the moisture-permeable paint allows the wooden exterior structure to omit the waterproof sheet 13. This is because waterproofing is ensured by the coating formed from the moisture-permeable paint. Since the moisture-permeable paint is applied directly to the insulating material 12, the pH of the moisture-permeable paint is adjusted to 6 to 8. This is because hydrolysis of the insulating material 12 (phenolic foam insulating material) can be suppressed.

[0056] The wooden exterior building material 21 is installed via furring strips 14 on a heat insulating material 12 to which a waterproof sheet 13 is attached and which is coated with a moisture-permeable paint.

[0057] The furring strips 14 are not particularly limited, but furring strips 14 made of metal, wood, or plastic can be used, and the furring strips 14 can be omitted provided that the base (coating made of moisture-permeable paint) is flat (with few unevenness).

[0058] Next, a construction method for a wooden exterior structure according to the embodiment will be described. The wood paint according to the embodiment includes the following steps: a first step of attaching insulating material 12 to exterior wall material 11; a second step of attaching waterproof sheet 13 to insulating material 12; a third step of applying a breathable paint to waterproof sheet 13; a fourth step of placing furring strips 14 on waterproof sheet 13 coated with the breathable paint; and a fifth step of fastening wooden exterior building materials 21 to furring strips 14.

[0059] The first step of attaching the insulating material 12 to the exterior wall material 11 is to attach the insulating material 12 to the exterior wall material 11 using nails, screws, adhesives, etc. Airtightness is ensured by applying general-purpose waterproof tape to the joints of the insulating material 12. The second step of attaching the waterproof sheet 13 to the insulating material 12 is to attach the waterproof sheet 13 to the insulating material 12 using pin tackers, nails, etc.

[0060] In the third step of applying the moisture-permeable paint to the waterproof sheet 13, the moisture-permeable paint is applied to the waterproof sheet 13 using a roller, a brush, or the like. The amount of paint applied is 100 to 150 g / m2 in terms of non-volatile matter. 2 The fourth step of placing the furring strips 14 on the waterproof sheet 13 coated with the moisture-permeable paint is to use screws or nails to fix the furring strips 14 to the insulation material 12 to which the waterproof sheet 13 coated with the moisture-permeable paint is attached.

[0061] In the fifth step of fixing the wooden exterior building material 21 to the furring strips 14, screws, nails, and adhesives are used to fix the wooden exterior building material 21 to the furring strips 14. The wooden exterior building material 21 can be positioned (fixed) by either a lattice joint or a butt joint, and when butting joints are used, tongue and groove joints can also be provided. The wooden exterior building material 21 can be positioned so that the grain of the wood that makes up the wooden exterior building material 21 runs horizontally. This is because this can prevent water absorption from the wood's ducts.

[0062] The wooden exterior structure constructed in this manner can be a wooden exterior structure equipped with wooden exterior building materials 21 on the exterior walls of a building, and can be a fire-resistant structure as defined in Article 2, Paragraph 8 of the Building Standards Act.

[0063] The wood exterior building material 21 provided with the coating 22 formed from wood paint can be made so that even if the coating peels off, the change in appearance is difficult to visually recognize, since small pieces of the coating peel off gradually. [Example]

[0064] The wood paint of the embodiment is a paint for wood with a different formulation, and is applied at a rate of 150 g / m to the surface of cedar lumber measuring 105 mm wide x 300 mm long x 12 mm thick. 2 The coating compositions of the examples and comparative examples, as well as the test results, are shown in Table 3.

[0065] Appearance changes The test specimens were exposed outdoors for one year, and the appearance was compared with that of a spare specimen (not exposed outdoors) to evaluate changes in appearance. The test specimens were then rated as ○ if there was almost no difference between them, △ if a difference was visible when placed side by side but not when observed from a distance, and × if a difference was visible even when observed from a distance.

[0066] Appearance similar to unpainted wood after deterioration The similarity of appearance to unpainted wood after deterioration was evaluated by exposing test specimens outdoors for one year and comparing their appearance with that of unpainted cedar lumber exposed under the same conditions. Exposed test specimens and unpainted wood that looked similar in appearance were given a ◎, those that showed a difference when placed side by side but looked natural when observed from a distance were given a ○, those that looked like the exposed test specimen had been further exposed to light were given a △, and those that looked very different were given an ×.

[0067] [Table 3]

[0068] The details of the ingredients are listed below.

[0069] Synthetic resin A Vinyl-modified epoxy ester resin Weight average molecular weight approximately 50,000 Non-volatile content 60% by mass Pencil hardness <6B Synthetic resin B Urethane-acrylic copolymer resin Weight average molecular weight approximately 1 million Non-volatile content 50% by mass Pencil hardness 2H Metal oxide coated mica Particle size 30μm Composition: Mica 70wt%, Titanium dioxide 29.5wt%, Silica 0.5wt% silica Particle size 3.4μm India ink A Type oil smoke ink Non-volatile content 19.5% by mass Ink particle size: 0.1 μm India ink B Type: Pine soot ink Non-volatile content 27.8% by mass Ink particle size: 0.1 μm The dispersant, antifoaming agent, preservative and antifreeze agent were selected from commercially available products.

[0070] Example 1 Example 1, which represents the best mode, uses synthetic resin A, which is a vinyl-modified epoxy ester resin, as the binder, India ink A as the ink, and metal oxide-coated mica and silica as additives. For the outdoor-exposed test specimen, the coating 22 transmits ultraviolet light, so the surface of the wood coated with the wood paint deteriorated (ashed) by ultraviolet light and turned roughly gray, while the coating 22 turned roughly gray due to the ink. The coating 22 of the outdoor-exposed test specimen had poor weather resistance and peeled off in small pieces, but because the pieces were small and the coating 22 and the surface of the wood (the areas where the coating 22 had peeled off) were similar in color (ΔE * = 5.0), the peeled areas were difficult to see from the outside, and could be seen as a single color. Therefore, when comparing the appearance of the outdoor-exposed specimen with the counter specimen, there was almost no difference. In addition, the gloss of the ink was emphasized by the metal oxide-coated mica, and the gloss of the coating 22 was suppressed by the silica, so the appearance of the outdoor-exposed specimen was closer to that of unpainted cedar lumber exposed under the same conditions.

[0071] (Examples 2 and 3) Example 2 is an example in which the amount of metal oxide-coated mica was increased from Example 1. Example 3 is an example in which the amount of metal oxide-coated mica was reduced and the amount of silica was increased from Example 1. When comparing the appearance of each outdoor-exposed test specimen with that of the spare test specimen, there was almost no difference, and the appearance was similar to that of unpainted cedar lumber exposed under the same conditions.

[0072] Examples 4 to 6 Example 4 is Example 1, except that the metal oxide-coated mica has been removed and the amount of silica has been increased. Example 5 is Example 1, except that the silica has been removed and the amount of metal oxide-coated mica has been increased. Example 6 is Example 1, except that the metal oxide-coated mica and silica have been removed. When comparing the appearance of each outdoor-exposed test specimen with that of the spare test specimen, there was almost no difference, but when compared with unpainted cedar lumber exposed under the same conditions, Example 4 lacked the ink gloss, Example 5 had a strong ink gloss, and Example 6 had a resin gloss; when they were placed side by side, there was no difference in appearance, but the differences were noticeable.

[0073] Example 7 In Example 7, the amount of synthetic resin was reduced, the amounts of metal oxide-coated mica and silica were adjusted, and a dispersant and antifoaming agent were added compared to Example 1. The test specimens exposed outdoors showed almost no difference in appearance when compared with the spare test specimens, and were similar in appearance to unpainted cedar lumber exposed under the same conditions.

[0074] Example 8 Example 8 is an example of Example 1 in which the amount of synthetic resin was increased, the ink was changed to India ink B, and the blending amounts of metal oxide-coated mica and silica were adjusted. When comparing the appearance of the outdoor-exposed test specimen with that of the spare test specimen, there was almost no difference, and the appearance was similar to that of unpainted cedar lumber exposed under the same conditions.

[0075] (Comparative Example 1) In Comparative Example 1, the synthetic resin used in Example 1 was changed to Synthetic Resin B, a urethane-acrylic copolymer resin with excellent weather resistance, and the ink was eliminated. The outdoor-exposed specimens showed little resin degradation, and although a wet color was visible, there was almost no UV degradation (ashing) of the wood surface, and they were in a state similar to that of unpainted boards. There was little difference from the test specimens, and while the difference was noticeable when placed side by side, it was imperceptible when separated. However, when compared to unpainted cedar lumber exposed under the same conditions, the unpainted cedar lumber showed UV degradation (ashing), resulting in a completely different appearance.

[0076] (Comparative Example 2) Comparative Example 2 is Comparative Example 1 with ink added. The outdoor-exposed test specimen showed little resin degradation, and although a wet color was visible, there was almost no UV degradation (ashing) of the wood surface, and it was in a state similar to that of an unpainted board, with little difference from the counter specimen; when placed side by side, the difference was noticeable, but when separated, the difference was imperceptible. Compared to unpainted cedar lumber exposed under the same conditions, UV degradation (ashing) was observed in the unpainted cedar lumber, and the outdoor-exposed test specimen of Comparative Example 2, to which ink was added, took on a nearly gray color; when placed side by side, the difference was noticeable, but when separated, there was no sense of incongruity. [Explanation of symbols]

[0077] 11...exterior wall material, 12...insulating material, 13...waterproof sheet, 14...furring strip, 21...wood exterior building material, 22...coating.

Claims

1. A composition containing, in terms of nonvolatile content, 40 parts by mass of vinyl-modified epoxy ester resin, 1 to 2 parts by mass of India ink, and 1 to 5 parts by mass of metal oxide-coated mica, The metal oxide-coated mica has a particle size of 10 to 100 μm.

2. The composition contains, in terms of nonvolatile content, 3 to 15 parts by mass of silica per 40 parts by mass of the vinyl-modified epoxy ester resin, 2. The wood paint according to claim 1, wherein the particle size of the silica is 1 to 10 μm.

3. A paint for wood as described in claim 1 or 2, characterized in that the weight average molecular weight of the vinyl-modified epoxy ester resin is 10,000 to 100,000.

4. A paint for wood as described in any one of claims 1 to 3, characterized in that the ink in the ink is lamp black ink.

5. A wooden exterior building material characterized by being coated with a coating film formed from a wood paint described in any one of claims 1 to 4.

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