Weather-resistant wood material and method for manufacturing weather-resistant wood material

Abstract

To provide a wood-based material with excellent weather resistance that can suppress appearance abnormalities (discoloration, cracking, blistering, etc.) for a long period of time, in which the surface of the wood is protected with a protective film (for example, transparent) that does not impair the texture and feel of the wood. [Solution] A weather-resistant wood material comprising wood, an adhesive layer formed on the surface of the wood, and a protective layer formed on the adhesive layer, wherein the surface layer of the wood contains a light stabilizer, and the protective layer contains a transparent urethane-based or epoxy-based resin, and further contains a light stabilizer, and the maximum tear strength value specified in JIS K6252:2015 is 5.5N or more.

Description

[Technical Field]

[0001] This invention relates to weather-resistant wood materials and methods for producing weather-resistant wood materials. [Background technology]

[0002] In recent years, in order to realize a decarbonized society, the use of wood has been increasing in buildings other than houses. In 2010, the "Act on the Promotion of the Use of Wood in Buildings, etc., to Contribute to the Realization of a Decarbonized Society" (formerly: Act on the Promotion of the Use of Wood in Public Buildings, etc.) was enacted, and the use of wood has been promoted by both the public and private sectors.

[0003] However, wood has inferior weather resistance compared to many other exterior building materials. When used in its raw state, it will discolor, crack, and deform in less than a year due to sunlight and rainwater, resulting in an unsightly appearance and reduced strength.

[0004] To address this problem, a method is known in which a protective layer containing a resin coating is formed on the surface of the wood, using a highly transparent protective coating, such as the polyurethane resin composition disclosed in Patent Document 1, so that the wood grain is visible from the outside, thereby improving the lifespan of the wood. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5638841 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, even with the method described in Patent Document 1, the weather resistance is still insufficient, and maintenance is required approximately once every 3 to 5 years. Therefore, the method described in Patent Document 1 has room for improvement in that it requires a shorter maintenance cycle and increases maintenance costs compared to metal or concrete exterior materials.

[0007] Furthermore, while one method to improve the weather resistance of wood is to conceal it with paint, this method makes the wood's original appearance invisible, making it difficult to meet the demand for improved aesthetics, thus leaving room for improvement.

[0008] Therefore, the present invention provides a wood-based material and a method thereof that have excellent weather resistance and can suppress appearance abnormalities (discoloration, cracking, blistering, etc.) for a long period of time, in which the surface of the wood is protected with a protective film (for example, transparent) that does not impair the texture and feel of the wood. [Means for solving the problem]

[0009] The inventors of this invention conducted extensive research to solve the above problems and discovered that by using a wood-based material with a specific structure, it is possible to suppress abnormalities in the appearance of the wood-based material (discoloration, cracking, swelling, etc.) for a long period of time, thus completing the present invention.

[0010] In other words, the present invention is as follows. [1] The material comprises wood, an adhesive layer formed on the surface of the wood, and a protective layer formed on the adhesive layer. The surface layer of the aforementioned wood contains a light stabilizer. The protective layer is a weather-resistant wood material containing a transparent urethane or epoxy resin, further containing a light stabilizer, and having a maximum tear strength of 5.5 N or more as defined in JIS K6252:2015. [2] The weather-resistant wood material according to [1], wherein the adhesive layer comprises a cured product of a film-forming coating that penetrates the surface of the wood. [3] The weather-resistant wood material according to [1] or [2], further comprising a step adjustment layer under the protective layer. [4] The weather-resistant wood material according to any one of [1] to [3], further comprising a design-forming layer on the surface of the protective layer, wherein the specular glossiness (60 degrees) defined in JIS K5600-4-7:1999 is 5 or less. [5] The weather-resistant wood material according to any one of [1] to [4], wherein the surface layer of the wood and / or the protective layer contains an ultraviolet absorber (UVA). [6] The weather-resistant wood material according to any one of [1] to [5], wherein the adhesive layer contains an ultraviolet absorber (UVA). [7] The weather-resistant wood material according to [4], wherein the design-forming layer contains an ultraviolet absorber (UVA). [8] The first step of impregnating the surface layer of the wood with a light stabilizer, The second step of forming an adhesive layer on the surface of the wood, and The third step of forming a protective layer containing a transparent urethane-based or epoxy-based resin containing a light stabilizer on the adhesive layer, at least including the manufacturing method of the weather-resistant wood material. [9] The manufacturing method of the weather-resistant wood material according to [8], wherein the adhesive layer in the second step is an adhesive layer formed by applying a film-forming paint having permeability to the surface of the wood.

Effect of the Invention

[0011] The weather-resistant wood material according to the present invention, for example, by using it to build a wooden building and manufacture wooden articles, even when affected by sunlight and rain, wooden buildings and wooden articles that utilize the texture of the wood can be provided. In these wooden buildings and wooden articles, it is possible to suppress appearance abnormalities (such as discoloration, cracking, swelling, etc.) over a long period.

Mode for Carrying Out the Invention

[0012] The following describes in detail embodiments for carrying out the present invention (hereinafter abbreviated as "this embodiment"). It should be noted that the present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of its gist.

[0013] <Weather-resistant wood material> The weather-resistant wood material of this embodiment is The material comprises wood, an adhesive layer formed on the surface of the wood, and a protective layer formed on the adhesive layer. The surface layer of the aforementioned wood contains a light stabilizer, The protective layer contains a transparent urethane or epoxy resin, and further contains a light stabilizer, and has a maximum tear strength of 5.5 N or more as defined in JIS K6252:2015. The weather-resistant wood material of this embodiment, with this configuration, can suppress appearance abnormalities (discoloration, cracking, blistering, etc.) for a long period of time and has excellent weather resistance.

[0014] <Wood> The wood used in this embodiment is not particularly limited, and wood suitable for the application can be selected. If it is to be used for construction purposes, wood suitable as a building material should be selected. In terms of the raw material of the wood, there are no particular limitations, but for example, any of the coniferous trees such as cedar, cypress, and larch, or the hardwoods such as zelkova and camphor can be selected. In terms of the processing method of the wood, there are no particular limitations, but for example, any of the following can be selected: solid wood, WOOD.ALC (Wooden ALC for exterior walls; Attain Low Carbon Society), CLT (Cross Laminated Timber), or LVL (Laminated Veneer Lumber).

[0015] <Light stabilizer> In the weather-resistant wood material of this embodiment, a light stabilizer is included in the surface layer of the wood to enhance its weather resistance. The light stabilizer is not particularly limited, but for example, a hindered amine light stabilizer (HALS) is preferred because it has the effect of capturing and neutralizing radicals generated by photodegradation.

[0016] In the weather-resistant wood material of this embodiment, the surface layer of the wood may contain an ultraviolet absorber (UVA). The weather-resistant wood material of this embodiment tends to have even better weather resistance when an ultraviolet absorber (UVA) is contained in the surface layer of the wood. The ultraviolet absorber (UVA) is not particularly limited, but examples include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, and benzylidene malonate-based ultraviolet absorbers, among which benzotriazole-based ultraviolet absorbers are preferred.

[0017] In the weather-resistant wood material of this embodiment, the surface layer of the wood is preferably 10 mm or less, 1 mm or less, and more preferably 0.3 mm or less, extending from the surface of the wood toward the inside of the wood.

[0018] <Adhesive layer> In the weather-resistant wood material of this embodiment, an adhesive layer is formed on the surface of the wood. When a protective layer, described later, is formed on the surface of the wood, the protective layer itself has adhesive force to the surface layer of the wood. However, the adhesive layer enhances the adhesive force between the protective layer and the surface layer of the wood, and as a result, the weather resistance of the weather-resistant wood material can be improved.

[0019] The materials used for the adhesive layer are not particularly limited, but examples include liquid film-forming coatings containing a film-forming resin and an adhesion promoter. The film-forming resin is not particularly limited, but examples include urethane resins and epoxy resins. The adhesion promoter is not particularly limited, but examples include silane coupling agents, epoxy resins, phenolic resins, acrylic resins, polyester resins, polyurethane resins, chlorinated rubber, and polyvinyl chloride resins.

[0020] The adhesive layer preferably contains a cured film-forming coating that penetrates the surface of the wood.

[0021] In the specific examples of film-forming resins and adhesion promoters (solvents) described above, if the film-forming resin or adhesion promoter is mixed without precipitation and has sufficient fluidity, the resulting film-forming coating will penetrate the surface of the wood regardless of how they are combined. Furthermore, if the viscosity is reduced using a solvent to dissolve the film-forming resin and adhesion promoter, the resulting film-forming coating will penetrate the surface of the wood regardless of how they are combined.

[0022] Specific examples of film-forming coatings that penetrate the surface of wood are not limited to, but include, for example, sealants and primers for adhesives.

[0023] The adhesive layer may contain a light stabilizer, an ultraviolet absorber (UVA), or both. It is preferable that the adhesive layer contains an ultraviolet absorber (UVA). The weather-resistant wood material of this embodiment tends to exhibit even greater weather resistance when the adhesive layer contains an ultraviolet absorber (UVA).

[0024] In the adhesive layer, the content of the light stabilizer is preferably 0 to 10% by mass, more preferably 1 to 7% by mass, and even more preferably 3 to 6% by mass. When the content of the light stabilizer in the adhesive layer is within the aforementioned range, the weather resistance and appearance of the weather-resistant wood material tend to be good.

[0025] Furthermore, it is preferable that the content of the ultraviolet absorber in the adhesive layer be 50% by mass or less. When the content of the ultraviolet absorber in the adhesive layer is within the above range, the weather resistance and appearance of the weather-resistant wood material tend to be good. The lower limit of the content of the ultraviolet absorber in the adhesive layer is not particularly limited, but for example, it is 0% by mass.

[0026] The light stabilizers and UV absorbers included in the adhesive layer are the same as those included in the surface layer of the wood as described above.

[0027] Furthermore, in the weather-resistant wood material of this embodiment, the thickness of the adhesive layer is preferably 0.005 to 0.060 mm, and more preferably 0.009 to 0.040 mm.

[0028] <Leveling layer> In the weather-resistant wood material of this embodiment, it is preferable to further include a step adjustment layer below the protective layer. More preferably, the step adjustment layer can be placed above the adhesive layer and below the protective layer. This makes it possible to suppress the difference in wet color between the step adjustment layer and the surrounding area when the step adjustment layer is in direct contact with the wood. Specifically, for example, after forming the step adjustment layer on the surface of the adhesive layer, the protective layer described later can be formed on top of the step adjustment layer. In particular, in areas where there are knots or the like on the wood surface, the wood surface is concave, so if the protective layer described later is formed directly on the surface of the adhesive layer, the concave shape of the wood surface will appear on the surface of the protective layer, which may impair the aesthetic appeal. Therefore, in areas where the wood surface is concave due to the presence of knots or the like, forming the step adjustment layer on the surface of the adhesive layer in particular tends to prevent the concavity of the wood surface from appearing on the surface of the protective layer, thereby maintaining the aesthetic appeal.

[0029] In this embodiment, the step adjustment layer refers to a layer that adjusts a concave portion, or a portion of another layer that has a concave step due to the influence of the concave portion, to a flat surface when a concave portion exists on the surface of the wood.

[0030] The material used for the leveling layer is not particularly limited, but examples include sealant color-matched to the same color as the level. Specific examples of sealant are not particularly limited, but examples include transparent Auton Clio Neo, which does not require color matching.

[0031] <Protective layer> In the weather-resistant wood material of this embodiment, a protective layer is formed on the surface of the adhesive layer (or on the surface of the step adjustment layer in areas where the step adjustment layer described above exists on the surface of the adhesive layer). The protective layer contains a transparent urethane-based or epoxy-based resin. It is preferable that it contains a transparent urethane-based resin.

[0032] Specific examples of transparent urethane resins are not limited, but include, for example, isocyanate group-containing urethane polymers. Isocyanate group-containing urethane polymers are obtained, for example, by reacting an organic isocyanate with an active hydrogen group-containing compound under conditions of excess isocyanate groups relative to active hydrogen (groups). The organic isocyanate is not limited, but includes, for example, organic polyisocyanates and mixtures of organic polyisocyanates and organic monoisocyanates.

[0033] The organic polyisocyanates are not particularly limited, but examples include toluene diisocyanates such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, diphenylmethane diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate, 1,2-phenylenediisocyanate, 1,3-phenylenediisocyanate, and 1 Phenylene diisocyanates such as ,4-phenylenediisocyanate, naphthalene diisocyanates such as 2,4,6-trimethylphenyl-1,3-diisocyanate, 2,4,6-triisopropylphenyl-1,3-diisocyanate, 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, chlorophenylene-2,4-diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl di Aromatic polyisocyanates such as phenylmethane-4,4'-diisocyanate and 3,3'-dimethoxyphenyl-4,4'-diisocyanate, and aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, decamethylene diisocyanate, and lysine diisocyanate. Examples include aromatic aliphatic polyisocyanates such as xylylene diisocyanates (e.g., xylylene diisocyanate, p-xylylene diisocyanate), and other xylylene diisocyanates; and alicyclic polyisocyanates such as 1,4-cyclohexidine diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. Furthermore, organic polyisocyanates such as polymethylene polyphenyl polyisocyanate and crude toluene diisocyanate can also be used. Modified isocyanates obtained by modifying these organic polyisocyanates, which contain one or more uretdione bonds, isocyanurate bonds, allophanate bonds, biuret bonds, uretonimine bonds, carbodiimide bonds, urethane bonds, urea bonds, etc., can also be used.

[0034] The organic monoisocyanates are not particularly limited, but examples include n-butyl monoisocyanate, n-hexyl monoisocyanate, n-hexadecyl monoisocyanate, n-octadecyl monoisocyanate, p-isopropylphenyl monoisocyanate, and p-benzyloxyphenyl monoisocyanate.

[0035] The active hydrogen group-containing compound is not particularly limited, but examples include high-molecular-weight and low-molecular-weight polyols, amino alcohols, polyamines, and compounds having at least one active hydrogen group and at least one ethylenically unsaturated group. These can be used individually or in combination of two or more.

[0036] Specific examples of transparent epoxy resins are not particularly limited, but include, for example, biphenyl-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AD-type epoxy resins, bisphenol S-type epoxy resins and their derivatives (e.g., hydrogenated or brominated compounds), novolac-type epoxy resins (e.g., cresol novolac-type epoxy resins, phenol novolac-type epoxy resins, etc.), glycidyl ester-type epoxy resins, as well as urethane-modified epoxy resins having urethane bonds, nitrogen-containing epoxy resins (e.g., epoxides of amines such as metaxylenediamine and hydantoin, glycidylamine-type epoxy resins such as tetraglycidyldiaminodiphenylmethane and triglycidyl paraaminophenol, etc.), rubber-modified epoxy resins (e.g., epoxy resins containing synthetic rubber such as polybutadiene or natural rubber as rubber components), cyclic aliphatic epoxy resins, and long-chain aliphatic epoxy resins. These can be used individually or in combination of two or more.

[0037] Furthermore, the protective layer contains a light stabilizer. Additionally, the protective layer may contain an ultraviolet absorber (UVA).

[0038] Here, "transparent" means that the opacity, as measured by the method specified in JIS K5600-4-1:1999, is less than 40%.

[0039] In the protective layer, the content of the light stabilizer is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 0.7 to 3% by mass. When the content of the light stabilizer in the protective layer is within the above range, the weather resistance and appearance of the weather-resistant wood material tend to be good.

[0040] Furthermore, the content of the ultraviolet absorber in the protective layer is preferably 0 to 15.0% by mass, and more preferably 0.5 to 10.0% by mass. When the content of the ultraviolet absorber in the protective layer is within the above range, weather resistance and appearance tend to be good.

[0041] The light stabilizers and ultraviolet absorbers included in the protective layer are the same as those included in the surface layer of the wood as described above.

[0042] Furthermore, in the weather-resistant wood material of this embodiment, the thickness of the protective layer is preferably 0.09 mm to 0.75 mm, and more preferably 0.21 mm to 0.33 mm.

[0043] <Design-forming layer> In the weather-resistant wood material of this embodiment, a decorative layer can be formed on the surface of the protective layer described above. The specular gloss (60 degrees) of the surface of the decorative layer, as defined in JIS K5600-4-7:1999, is preferably 5 or less. By providing a decorative layer with a specular gloss of 5 or less on the surface of the protective layer, an appearance similar to real (natural) wood can be obtained.

[0044] The materials used for the design-forming layer are not particularly limited, but examples include matting materials. Specific examples of matting materials are not particularly limited, but examples include various waxes such as polyolefin wax, beeswax, carnauba wax, montan wax, and paraffin wax, as well as higher aliphatic compounds such as stearic acid amide.

[0045] Furthermore, the design-forming layer may contain a light stabilizer (e.g., HALS), an ultraviolet absorber (UVA), or both.

[0046] In the design-forming layer, the content of the light stabilizer is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 2.5% by mass, and even more preferably 0.3 to 1.5% by mass. When the content of the light stabilizer in the design-forming layer is within the above range, weather resistance and appearance tend to be good.

[0047] Furthermore, the content of the ultraviolet absorber in the design-forming layer is preferably 70% by mass or less. When the content of the ultraviolet absorber in the design-forming layer is within the above range, weather resistance and appearance tend to be good. The lower limit of the content of the ultraviolet absorber in the design-forming layer is not particularly limited, but for example, it is 0% by mass.

[0048] Furthermore, the light stabilizers and ultraviolet absorbers contained in the design-forming layer are the same as those contained in the surface layer of the wood as described above.

[0049] Furthermore, a matting agent can be incorporated into the protective layer, allowing it to serve as both a protective layer and a design-forming layer.

[0050] Furthermore, in the weather-resistant wood material of this embodiment, the thickness of the design-forming layer is preferably 0.001 to 0.1 mm, more preferably 0.005 to 0.08 mm, and even more preferably 0.01 to 0.05 mm.

[0051] <The force that tears the protective layer> In the weather-resistant wood material of this embodiment, the protective layer has a maximum tear force of 5.5 N or more.

[0052] In this embodiment, the tear force (N) of the protective layer is measured by a tensile test specified in JIS K6252:2015 and is defined by the following formula.

[0053] Tear force (N) = Tear strength (N / m) × Thickness of protective layer (m)

[0054] Normally, tear strength is proportional to the thickness (m) of the protective layer and is expressed as tear strength per unit thickness (m) (N / m). However, in order to exhibit weather resistance, the actual tearing force (N) must be above a certain value. In the weather-resistant wood material of this embodiment, the maximum value of the tearing force of the protective layer is 5.5N or more, and preferably 13N or more. In the weather-resistant wood material of this embodiment, if the maximum value of the tearing force of the protective layer is 5.5N or more, shrinkage of the wood is suppressed, so the protective film of the protective layer does not crack, and thus weather resistance can be ensured. In the weather-resistant wood material of this embodiment, the upper limit of the maximum value of the tearing force of the protective layer is not particularly limited, but for example, it is 43.5N.

[0055] The tearing force of the protective layer can be adjusted by the selection of the protective layer material, the adjustment of the protective layer thickness, or both. Furthermore, the thickness of the protective layer can be adjusted by the amount of resin applied to form the protective layer (weight per unit area).

[0056] <Elongation at break> In this embodiment, the elongation of the protective layer at break is measured according to JIS K6251:2017. In the weather-resistant wood material of this embodiment, it is preferable that the elongation of the protective layer at break is 200% or more. By having an elongation of 200% or more at break, even if the protective film shrinks (note: or "even if the wood deforms and displacement occurs"), the protective film will only stretch and will not crack, thus exhibiting weather resistance. From a similar viewpoint, in the weather-resistant wood material of this embodiment, it is more preferable that the elongation of the protective layer at break is 200% to 400%.

[0057] The elongation of the protective layer at rupture can be adjusted by selecting the material of the protective layer, adjusting the thickness of the protective layer, or both.

[0058] <Water permeability> In this embodiment, the water permeability of the protective layer can be measured by the method specified in JIS A6909:2014. In the weather-resistant wood material of this embodiment, it is preferable that the water permeability of the protective layer is 0.5 mL / 24h or less. In the weather-resistant wood material of this embodiment, if the water permeability of the protective layer is 0.5 mL / 24h or less, water penetration into the wood from the outside becomes less likely, and thus corrosion and swelling of the wood surface caused by water penetration become less likely. From a similar viewpoint, in the weather-resistant wood material of this embodiment, it is more preferable that the water permeability of the protective layer is 0.5 mL / 24h or less, and even more preferable that it is 0.2 mL / 24h or less.

[0059] The water permeability of the protective layer can be adjusted by selecting the material of the protective layer, adjusting the thickness of the protective layer, or both.

[0060] <Weather resistance> In this embodiment, the weather resistance of the weather-resistant wood material is expressed as the time from the start of the exposure test until any abnormal appearance (discoloration, cracking, blistering, etc.) occurs, by operating the exposure test machine in "Cycle A" according to the procedure specified in JIS K5600-7-7:2008. In the weather-resistant wood material of this embodiment, the weather resistance is preferably 2,500 hours or more, more preferably 4,000 hours or more, and even more preferably 10,000 hours or more. In the weather-resistant wood material of this embodiment, having a weather resistance of 2,500 hours or more means that it possesses weather resistance equivalent to the performance category "Weather Resistance Class 1" as defined in "N-2 Weather-Resistant Coated Wood Building Materials" of the "Quality Performance Evaluation Standards for Excellent Wood Building Materials, etc." (https: / / www.howtec.or.jp / files / libs / 2510 / 201902051842148985.pdf) formulated by the Japan Housing and Wood Technology Center. In the weather-resistant wood material of this embodiment, there is no particular upper limit to the weather resistance, but at present, the appearance has been confirmed to be sound after 20,500 hours.

[0061] In the weather-resistant wood material of this embodiment, by adopting the specific configuration described above, the weather resistance can be set to the aforementioned range.

[0062] <Concealing ability> In this embodiment, the hiding power of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if an adhesive layer and design-forming layer are present) is measured by the method specified in JIS K5600-4-1:1999. In the weather-resistant wood material of this embodiment, it is preferable that the hiding power of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if an adhesive layer and design-forming layer are present) is less than 40%. In the weather-resistant wood material of this embodiment, if the hiding power of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if an adhesive layer and design-forming layer are present) is less than 40%, the pattern on the wood surface becomes easily visible from the outside even with the protective film, and the design quality of the wood pattern is not lost. From a similar viewpoint, in the weather-resistant wood material of this embodiment, it is more preferable that the hiding power of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if an adhesive layer and design-forming layer are present) is 30% or less, and even more preferable that it is 20% or less. The lower limit of this concealment ability is not particularly limited, but for example, it is 0%.

[0063] The opacity of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if applicable) can be adjusted by selecting the material of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if applicable), adjusting the thickness of the protective layer (or the entire adhesive layer, protective layer, and design-forming layer if applicable), or both.

[0064] <Water vapor transmission rate> In the weather-resistant wood material of this embodiment, the water vapor transmission rate of the protective layer (including the adhesive layer, protective layer, and design-forming layer if applicable) under 40°C and 90%RH conditions as defined in JIS Z 0208:1976 is 30 g / m². 2 ·120g / m for 24 hours or more 2 It is preferable that the water vapor permeability is 24 hours or less. In the weather-resistant wood material of this embodiment, the water vapor permeability of the protective layer (if it has an adhesive layer and a decorative layer, the adhesive layer, protective layer, and decorative layer as a whole) is 30 g / m². 2· If it is more than 24 hours, even if the wood is moist, the external diffusion of water vapor is likely to proceed. Therefore, it is possible to prevent wood corrosion caused by moisture and swelling or peeling of the protective layer caused by water vapor pressure. On the other hand, in the weather-resistant wood material of the present embodiment, the water vapor permeability of the protective layer (when having an adhesive layer and a design formation layer, the entire adhesive layer, protective layer, and design formation layer) is 120 g / m 2 · If it is 24 hours or less, it is possible to prevent the intrusion of moisture into the wood and similarly prevent the corrosion of the wood caused by moisture. From the same perspective, in the weather-resistant wood material of the present embodiment, the water vapor permeability of the protective layer (when having an adhesive layer and a design formation layer, the entire adhesive layer, protective layer, and design formation layer) is 50 g / m 2 · More preferably, it is more than 24 hours and 120 g / m 2 · It is more preferably 24 hours or less, and 60 g / m 2 · More preferably, it is more than 24 hours and 100 g / m 2 · 24 hours or less g / m 2 · Even more preferably, it is 24 hours.

[0065] The water vapor permeability of the protective layer (when having an adhesive layer and a design formation layer, the entire adhesive layer, protective layer, and design formation layer) can be adjusted by selecting the material of the protective layer (when having an adhesive layer and a design formation layer, the entire adhesive layer, protective layer, and design formation layer), adjusting the thickness of the protective layer (when having an adhesive layer and a design formation layer, the entire adhesive layer, protective layer, and design formation layer), or both.

[0066] <Manufacturing Method of Weather-Resistant Wood Material> The manufacturing method of the weather-resistant wood material of the present embodiment is a first step of impregnating a light stabilizer into the surface layer of the wood, a second step of forming an adhesive layer on the surface of the wood, and a third step of forming a protective layer containing a transparent urethane-based or epoxy-based resin containing a light stabilizer on the adhesive layer, and at least includes these.

[0067] <First Step> In the method for manufacturing weather-resistant wood material according to this embodiment, the first step is to impregnate the surface layer of the wood with a light stabilizer. In the first step, the surface layer of the wood may be impregnated with an ultraviolet absorber along with the light stabilizer.

[0068] The process of impregnating the surface of the wood with light stabilizers and UV absorbers is not particularly limited, but can be carried out, for example, by applying a liquid impregnating paint containing light stabilizers and UV absorbers but without film-forming resins to the surface of the wood and allowing the volatile components contained in the impregnating paint to volatilize.

[0069] In the impregnation paint used in the first step, the content of the light stabilizer is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass.

[0070] Furthermore, in the impregnation paint used in the first step, the content of the ultraviolet absorber is preferably 0 to 20% by mass, more preferably 3 to 15% by mass, and even more preferably 5 to 10% by mass.

[0071] <Second process> In the method for manufacturing weather-resistant wood material according to this embodiment, the second step is to form an adhesive layer on the surface of the wood. Preferably, the adhesive layer in the second step is formed by applying a penetrating film-forming paint to the surface of the wood. By using a penetrating paint here, it is easy to obtain an anchoring effect on the wood surface of the adhesive layer. Furthermore, by using a film-forming paint here, a strengthening effect on the wood surface can be expected. In addition to the improvement of adhesion by the adhesion promoter, these two effects result in an adhesive layer with superior adhesion, making it easier to form a protective layer on its upper surface, as described later.

[0072] The process of forming an adhesive layer on the surface of wood is not particularly limited, but can be carried out, for example, by applying a liquid film-forming coating containing a film-forming resin and an adhesion promoter to the surface of the wood. The adhesive layer may contain a light stabilizer, an ultraviolet absorber (UVA), or both. The method of incorporating the light stabilizer and UV absorber into the adhesive layer is not particularly limited, but for example, one method is to add the light stabilizer and UV absorber to a film-forming coating to be applied to the surface of the wood, and then apply the film-forming coating to the surface of the wood.

[0073] <2nd process> In the method for manufacturing weather-resistant wood material according to this embodiment, a second' step of forming a step adjustment layer may be included before the third step of forming a protective layer, which will be described later.

[0074] The formation of the step adjustment layer is not particularly limited, but can be done, for example, by filling the surface of the adhesive layer with a sealant.

[0075] <3rd process> In the method for manufacturing weather-resistant wood material according to this embodiment, the third step is to form a protective layer containing a transparent urethane-based or epoxy-based resin containing a light stabilizer on top of the adhesive layer (or on the surface of the step adjustment layer in areas where the step adjustment layer described above exists on the surface of the adhesive layer).

[0076] The protective layer can be formed from a transparent urethane-based or epoxy-based resin, but is preferably formed from a transparent urethane-based resin. Furthermore, the transparent urethane-based or epoxy-based resin contains a light stabilizer, but may also contain an ultraviolet absorber (UVA).

[0077] Furthermore, in the third step, a matting agent, as described later, can be incorporated into the protective layer.

[0078] In this context, "transparent" refers to a material with an opacity of less than 40%, as measured by the method specified in JIS K5600-4-1:1999.

[0079] <4th process> The method for manufacturing weather-resistant wood material according to this embodiment may include a fourth step of forming a design-forming layer on the surface of the protective layer.

[0080] The process of forming a design layer on the surface of the protective layer is not particularly limited, but one example is to apply a matting agent to the surface of the protective layer. In addition, in the fourth step, the design layer may contain a light stabilizer (e.g., HALS), an ultraviolet absorber (UVA), or both. [Examples]

[0081] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0082] (Example 1) A laminated timber called "WOOD.ALC" (registered trademark), manufactured by Kyowa Lumber Co., Ltd. using domestically produced Japanese cedar and bonded together with a resorcinol resin adhesive suitable for use in environment A, was cut into a rectangular prism with dimensions of 75mm x 50mm x 10mm. The following steps 1 to 3 were performed on the 75mm x 50mm end grain surface (hereinafter referred to as the "evaluation surface"). When cutting the rectangular prism portion, the cut area was adjusted so that the bonded surface with adhesive was visible on the evaluation surface.

[0083] (Step 1) A liquid ethyl acetate-based impregnation coating containing 15% by mass of "ADEKA Stab LA-63P," a hindered amine-based light stabilizer (hereinafter also referred to as "HALS") manufactured by ADEKA Corporation, and without film-forming resin, is applied to the evaluation surface at a rate of 100 g / m². 2 The paint was applied in the specified amount and left for 60 minutes in an indoor atmosphere to completely release its volatile components and impregnate the wood surface with the light stabilizer, thereby obtaining the raw material. This process is referred to as "Step 1".

[0084] (Step 2) To form an adhesive layer, a primer (OP-2020) manufactured by Auto Chemical Industry Co., Ltd. (hereinafter referred to as "primer") containing 1.5% by mass of the same light stabilizer used in Step 1 is applied to the surface of the original material at a rate of 100 g / m². 2 Only the adhesive was applied, and it was left for 60 minutes in an indoor environment to form an adhesive layer on the surface of the wood. This step will be referred to as "Step 2".

[0085] (Step 3) To form a protective layer, a one-component transparent urethane resin containing 0.78% by mass of the same light stabilizer used in Step 1 (corresponding to Example 4 of Patent Document 1; hereinafter referred to as "transparent urethane resin"; with an opacity of less than 40% as measured by the method specified in JIS K5600-4-1:1999) is applied at a rate of 500 g / m² to the surface of the adhesive layer formed in the previous step 2. 2 The specified amount was applied and left overnight in an atmosphere of 23°C and 50% relative humidity to form a protective layer. This step is referred to as "Step 3".

[0086] The test specimens obtained through steps 1, 2, and 3 described above were designated as the weather-resistant wood material of Example 1. The weather resistance and tear strength of the protective layer of the weather-resistant wood material of Example 1 were measured as follows. The measurement results are shown in Table 1.

[0087] <Measurement of weather resistance> The weather resistance of the test specimens was measured according to the procedure specified in JIS K5600-7-7:2008, using the wet cycle test "Cycle A". An Atlas Ci4000 weather resistance tester was used for the measurements. The irradiance was 60 W / m². 2 Exposure to the test specimens was initiated. After the start of exposure, the test specimens were visually observed every 500 hours to check for any abnormalities in appearance (discoloration, cracking, blistering, etc.). If any abnormalities were observed, the elapsed time at the last observation when no abnormalities were observed was used as the evaluation result of the weathering test. For example, if no abnormalities were observed until 3500 hours, but an abnormality was first observed at 4000 hours, the result of the weathering test was recorded as "3500 hours".

[0088] Furthermore, if no external abnormalities are observed after more than 2500 hours, the test may be stopped without any external abnormalities being observed. In such cases, the elapsed time (in 500-hour increments) at the last time no external abnormalities were observed was used as the evaluation result of the weathering test. For example, if no external abnormalities were observed up to 4000 hours, and the weathering test was stopped before 4500 hours had passed, the result of the weathering test was recorded as "4000 hours or more".

[0089] <Measurement of tearing force of the protective layer> The tearing force (N) of the protective layer was measured by the method described below.

[0090] First, the same urethane resin used for the protective layer was applied to a 1 mm thick area surrounded by a 1 mm thick corner backer on the release paper. The area was then cured for 14 days at 23°C and 50% RH, and a test specimen was punched out. The thickness (mm) of the test specimen was accurately measured using a digital thickness gauge manufactured by Toyo Seiki Seisakusho Co., Ltd., and the tear strength (N / m) was measured according to the method specified in JIS K6252:2015. An angled shape was selected for the test specimen when measuring the tear strength.

[0091] Next, the application amount is 200g / m². 2 Based on the fact that the average thickness of the cured film per unit area is 0.12 mm, and that variations of ±0.03 mm can occur, the actual amount applied to the painted surface (g / m²) 2 ) 0.12mm / 200g / m 2 = 0.06 (mm·m) 2 The thickness of the protective layer (mm) in the test specimen was calculated by multiplying the value (mm) obtained by ( / g) by 0.03 mm to ensure safety.

[0092] Finally, the tearing force (N) of the protective film was obtained by multiplying the tear strength (N / m) obtained above by the thickness (mm) of the protective layer, as shown in the formula below.

[0093] Tear force (N) = Tear strength (N / m) × Thickness of protective layer (mm) / 1000

[0094] (Example 2) As shown in Table 1, the evaluation surface is the quarter-sawn surface of the 116mm x 66mm rectangular prism cut from the laminated timber "WOOD.ALC" (registered trademark) with dimensions of 116mm x 66mm x 30mm.

[0095] In step 2, the primer contained 15% by mass of the ultraviolet absorber "EVERSORB 89" (hereinafter also referred to as "UVA") manufactured by Everlight Chemical Industrial, instead of a light stabilizer.

[0096] In the adhesive layer formed by step 2, a step (referred to as step 2') was performed once, in which "Auton Clio Neo" manufactured by Auto Chemical Industry Co., Ltd. was applied as a step-adjusting layer only to the areas of the wood that had knots on the surface. The amount of transparent urethane resin applied in step 3 is 200g / m². 2 Being After step 3, 50 g / m² of topcoat manufactured by Auto Chemical Industry Co., Ltd. is applied to the surface of the protective layer, containing 0.12% by mass of a hindered amine-based light stabilizer and 3% by mass of polyolefin wax as a matting agent. 2 The process of applying the coating and drying it for 14 days (referred to as "Step 4") was carried out. Except for a few exceptions, test specimens were prepared under the same conditions as in Example 1. The prepared test specimens were designated as the weather-resistant wood material of Example 2. Weather resistance and tear strength of the protective layer were measured for the weather-resistant wood material of Example 2 as described above. The measurement results are shown in Table 1.

[0097] (Example 3) As shown in Table 1, test specimens were prepared under the same conditions as in Example 1, except that each condition was changed. The prepared test specimens were designated as the weather-resistant wood material of Example 3. Weather resistance and tear strength of the protective layer were measured for the weather-resistant wood material of Example 3 as described above. The measurement results are shown in Table 1.

[0098] (Example 4) As shown in Table 1, in Example 1, after step 3, 0.12% by mass of a hindered amine-based light stabilizer and 3% by mass of polyolefin wax as a matting agent were added to the surface of the protective layer as a design forming layer, and 50 g / m of topcoat manufactured by Auto Chemical Industry Co., Ltd. was applied. 2 Except for the step of applying the coating and drying it for 14 days (referred to as "Step 4"), test specimens were prepared under the same conditions as in Example 1. The prepared test specimens are designated as the weather-resistant wood material of Example 4. The weather resistance and tear strength of the protective layer of the weather-resistant wood material of Example 3 were measured as described above. The measurement results are shown in Table 1.

[0099] (Examples 5-13) As shown in Tables 1 and 2, test specimens were prepared under the same conditions as in Example 1, except that each condition was changed. The prepared test specimens were designated as the weather-resistant wood materials for Examples 5 to 13. Weather resistance and tear strength of the protective layer were measured for the weather-resistant wood materials of Examples 5 to 13 as described above. The measurement results are shown in Tables 1 and 2.

[0100] (Comparative Example 1) As shown in Table 3, in Example 1, steps 1 and 2 were not performed. The amount of transparent urethane resin to be applied in step 3 is 100 g / m². 2 That was the case. Except for the exceptions, test specimens were prepared under the same conditions as in Example 1. The prepared test specimens were designated as the wood material for Comparative Example 1. Weather resistance and tear strength of the protective layer were measured for the wood material of Comparative Example 1 as described above. The measurement results are shown in Table 3.

[0101] (Comparative Example 2) As shown in Table 3, in Example 1, steps 1 and 2 were not performed. The amount of transparent urethane resin to be applied in step 3 is 200 g / m². 2 That was the case. The coated transparent urethane resin contained 5.6% by mass of the same UV absorber used in Example 2. Except for the exceptions, test specimens were prepared under the same conditions as in Example 1. The prepared test specimens were designated as the wood material for Comparative Example 1. Weather resistance and tear strength of the protective layer were measured for the wood material of Comparative Example 1 as described above. The measurement results are shown in Table 3.

[0102] (Comparative Example 3) As shown in Table 3, in Example 1, step 1 was not performed. The amount of transparent urethane resin to be applied in step 3 is 200 g / m². 2 That was the case. The fact that step 4 in Example 2 was performed, Except for the exceptions, test specimens were prepared under the same conditions as in Example 1. The prepared test specimens were designated as the wood material for Comparative Example 3. Weather resistance and tear strength of the protective layer were measured for the wood material of Comparative Example 3 as described above. The measurement results are shown in Table 3.

[0103] (Comparative Examples 4-5) As shown in Table 3, test specimens were prepared under the same conditions as in Example 1, except that each condition was changed. The prepared test specimens were designated as the wood materials for Comparative Examples 4 and 5. Weather resistance and tear strength of the protective layer were measured for the wood materials of Comparative Examples 4 and 5 as described above. The measurement results are shown in Table 3.

[0104] The thickness of each layer in each example and comparative example, as well as the UVA concentration and HALS concentration, are shown in Table 4.

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

[0108] [Table 4]

Claims

1. The material comprises wood, an adhesive layer formed on the surface of the wood, and a protective layer formed on the adhesive layer. The surface layer of the aforementioned wood contains a light stabilizer. The protective layer is a weather-resistant wood material containing a transparent urethane or epoxy resin, further containing a light stabilizer, and having a maximum tear strength of 5.5 N or more as defined in JIS K6252:2015.

2. The weather-resistant wood material according to claim 1, wherein the adhesive layer includes a cured product of a film-forming coating that penetrates the surface of the wood.

3. The weather-resistant wood material according to claim 1 or 2, further comprising a step-adjusting layer beneath the protective layer.

4. The weather-resistant wood material according to claim 1 or 2, further comprising a design-forming layer on the surface of the protective layer having a specular gloss (60 degrees) of 5 or less as defined in JIS K5600-4-7:1999.

5. The weather-resistant wood material according to claim 1 or 2, wherein the surface layer and / or protective layer of the wood contains an ultraviolet absorber (UVA).

6. The weather-resistant wood material according to claim 1 or 2, wherein the adhesive layer contains an ultraviolet absorber (UVA).

7. The weather-resistant wood material according to claim 4, wherein the design forming layer contains an ultraviolet absorber (UVA).

8. The first step involves impregnating the surface layer of the wood with a light stabilizer. A second step of forming an adhesive layer on the surface of the wood, A method for producing a weather-resistant wood material, comprising at least a third step of forming a protective layer containing a transparent urethane-based or epoxy-based resin containing a light stabilizer on the adhesive layer.

9. The method for producing a weather-resistant wood material according to claim 8, wherein the adhesive layer of the second step is an adhesive layer formed by applying a penetrating film-forming paint to the surface of the wood.

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