JP2019177685A - Woody member - Google Patents

Abstract

To provide a woody member which has both high light stability and surface durability and is excellent in weather resistance.SOLUTION: A woody member has a light stabilizer holding surface that is formed of a surface holding a hindered amine-based light stabilizer having a stable free radical on at least a part of a surface of a woody base material, in which the light stabilizer holding surface is covered with a protective layer formed of a cured product of a radical polymerization type curable resin composition through an isolation layer formed of a solidification product of a resin composition other than the radical polymerization type curable resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an outdoor wood-based member.

Wood has a beautiful wood texture and color tone that makes it feel warm, but it has material properties that it is easily damaged, is not easily soiled, and is subject to discoloration. For this reason, when wood is used outdoors, a wood-based member having a surface subjected to weathering treatment is generally used.
As such a weathering treatment, a technique for forming a resinous protective layer that imparts durability (scratch resistance, contamination resistance, strength, etc.) to the surface of wood is known.
In addition, lignin and polyphenols contained in wood are radically decomposed by sunlight, particularly ultraviolet rays, and cause a discoloration by radical chain reaction. Therefore, a technique for adding a light stabilizer to the wood surface is known. .

In Patent Document 1, a treatment layer is formed on a surface layer of a wood-based substrate with a weather resistance-modifying composition comprising a light stabilizer, and a film layer is further formed on the treatment layer via an adhesive layer. A wood-based member is disclosed which is characterized by being formed. This document describes that it is preferable to use a hindered amine light stabilizer (HALS) having an action of scavenging radicals as the light stabilizer.
Patent Document 2 discloses that light-induced degradation is achieved by treatment with an impregnation system that penetrates the surface of a tree containing a) water without an organic solvent and b) a selected sterically hindered amine N-oxyl or N-hydroxyl. A method for protecting trees against is disclosed. Patent Document 2 describes a complete wood protection system including the impregnation system, in some cases, an intermediate layer, and a final topcoat. In the examples, a cured product of alkyd resin is used as the topcoat. It is stated.

JP 2006-007515 A Special table 2003-508503 gazette

Here, instead of the film used as a protective layer in the wood-based member of Patent Document 1 or the cured product of the alkyd resin of Patent Document 2, a primer (underlying) layer is formed on the surface of the wooden substrate, and then radicals are formed. A technique for forming a protective layer by applying a polymerizable curable resin composition and curing the composition is known. In this way, in the case of curing after applying the radical polymerization type curable resin composition to the wooden substrate, it is possible to maintain a higher wood texture than pasting the formed film described in Patent Document 1, A woody member having high followability to the surface shape, easy thickness control, and excellent flame retardancy and incombustibility can be obtained. Moreover, since the cured product of the radical polymerization type curable resin is superior in scratch resistance to the cured product of the alkyd resin described in Patent Document 2, the durability is high and the weather resistance is excellent. Application of is desired.
In addition, among HALS described as preferred light stabilizers in Patent Document 1 and Patent Document 2, when HALS having a stable free radical that has a particularly strong action of scavenging radicals is used, deterioration due to changes in wood components is suppressed. Therefore, application to a wooden member for outdoor use is desired.
However, as a result of studies by the present inventors, a wood-based member having both a HALS having a stable free radical and a cured product of a radical polymerization type curable resin composition cannot be obtained only by combining these materials.
The present invention has been accomplished in view of the above-described actual situation, and an object thereof is to provide a wood-based member having high light stability and surface durability and excellent weather resistance.

  The wooden member of the present invention includes a light stabilizer holding surface comprising a surface holding a hindered amine light stabilizer having a stable free radical on at least a part of the surface of the wooden substrate, and the light stabilizer holding surface. However, it is covered with a protective layer made of a cured product of the radical polymerization type curable resin composition through an isolation layer made of a solidified product of a composition other than the radical polymerization type curable resin.

  In the present invention, the hindered amine light stabilizer having the stable free radical is 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-acetamido-2,2,6,6-tetramethyl. Selected from the group consisting of piperidine 1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl, and 4-oxo-2,2,6,6-tetramethylpiperidine 1-oxyl. It is preferable that it is at least one compound.

  In the present invention, the radical polymerizable curable resin composition is preferably an ionizing radiation curable radical polymerizable resin composition.

  ADVANTAGE OF THE INVENTION According to this invention, the wood type member excellent in the weather resistance which has high light stability and surface durability can be provided.

The present invention comprises a wood substrate 1, a light stabilizer holding surface 2 impregnated and held with HALS having a stable free radical having an uneven surface, a separating layer 3 having a flattened surface, and a protective layer 4. 3 is a schematic diagram showing an example of a wood-based member 100. FIG. An example of the wood-based member 100 of the present invention comprising the wooden substrate 1, the light stabilizer holding surface 2, the isolation layer 3, and the protective layer 4 whose surfaces are flattened by a layer containing HALS having stable free radicals. It is a schematic diagram shown. Wood substrate 1, light stabilizer holding surface 2 impregnated and held with HALS having stable free radicals having an uneven surface, isolation layer 3 having an uneven surface, and protective layer 4 having a flattened surface It is a schematic diagram which shows the example of the wooden member 100 of this invention provided with this. It is a schematic diagram which shows the example of the wood-based member 200 of the prior art provided with the wooden base material 1, the light stabilizer holding surface 2, the primer layer 5, and the protective layer 4. FIG.

Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the spirit of the present invention.
In the present invention, (meth) acrylate represents each of acrylate or methacrylate.

  The wood-based member of the present invention is provided with a light stabilizer holding surface comprising a surface holding a hindered amine light stabilizer having a stable free radical on at least a part of the surface of the wooden substrate, and the light stabilizer holding The surface is covered with a protective layer made of a cured product of the radical polymerization type curable resin composition via an isolation layer made of a solidified product of the resin composition other than the radical polymerization type curable resin.

If the light stabilizer holding surface consisting of the surface holding HALS with stable free radicals and the coating layer of the radical polymerization type curable resin composition are adjacent to each other, HALS with stable free radicals will move to the coating layer. Thus, free radicals necessary for curing the radical polymerization type curable resin composition are captured, and thus the radical polymerization type curable resin composition cannot be cured. Therefore, conventionally, a light stabilizer holding surface made of a surface holding HALS having stable free radicals and a protective layer made of a cured product of a radical polymerization type curable resin composition are combined, and a wood member having excellent weather resistance is obtained. I couldn't.
Here, in general, a protective layer made of a cured product of a radical polymerization type curable resin composition is coated on the surface of a wooden substrate via a primer layer in order to ensure adhesion with the wooden substrate. Yes. However, the radical polymerization type curable resin composition was not cured simply by having a primer layer between the protective layer and the light stabilizer holding surface comprising the surface holding HALS having stable free radicals.
As shown in FIG. 4, the surface of the wooden substrate 1 has some unevenness due to the characteristics of the wood. Even the conventional woody member 200 has a primer layer 5 between the woody substrate 1 and the protective layer 4 in order to improve the adhesion of the protective layer 4 made of a cured product of a radical polymerization type curable resin composition. However, since the function required for the primer layer 5 is adhesiveness, the primer layer 5 was not made thicker than necessary as long as the adhesiveness can be satisfied.
However, since the present inventors have a very strong radical scavenging action since HALS having a stable free radical, as shown in FIG. 4, the light stabilizer holding surface 2 composed of a surface for holding HALS having a stable free radical, It has been found that when even a part of the protective layer 4 (the coating layer of the radical polymerization type curable resin composition) comes into contact, the radical polymerization type curable resin composition does not cure.
As illustrated in FIG. 1, in the wood member 100 of the present invention, the light stabilizer holding surface 2 and the protective layer are used as the isolation layer 3 provided with the isolation function added to the primer layer 5 having the adhesion function of the prior art. 4 (a coating layer of a radical polymerization type curable resin composition) can be provided between the light stabilizer holding surface 2 and the protective layer 4 to provide a highly weatherable wood-based member. It was.
Hereinafter, it demonstrates in detail in order of the manufacturing method of the wood type member of this invention and the wood type member of this invention.

1. Woody member (1) Woody base material There is no particular limitation on the type of wood used as the woody base material of the woody member of the present invention. As the wood substrate, for example, well-known wood veneer, plywood, laminated wood, particle board, fiber board, etc. made of wood such as cedar, firewood, pine, firewood, firewood, firewood, teak, lawan, rubber tree, etc. A thing can be used suitably. The shape of the wood substrate is not particularly limited, and various shapes such as a flat plate, a curved plate, and a columnar body can be used. The thickness in the case of a flat plate or a curved plate is not particularly limited, but a thickness of about 0.1 mm to 100 mm is usually used. In particular, even wood that is not suitable for outdoor use, such as cedar and straw, which is easily discolored by photo-oxidation, can be provided with high weather resistance, and thus can be used as a wooden member that can be used outdoors.
In addition, the surface of the wooden substrate may have a certain degree of unevenness due to the characteristics. However, if the unevenness is large, the isolation layer and the light stabilizer holding surface are thickened and the radical is removed from the light stabilizer holding surface. Since it is necessary to block the transfer of HALS having stable free radicals to the coating surface of the polymerizable curable resin composition, it is preferable to use the surface after flattening to some extent. From such a viewpoint, the surface roughness of the wooden substrate is preferably in the range of 20 μm or less, and more preferably in the range of 10 μm or less, as JIS B0601 (1994) default centerline average roughness Ra. preferable.

(2) Light stabilizer holding surface The woody member of the present invention has a light stabilizer holding surface comprising a surface holding a hindered amine light stabilizer having a stable free radical on at least a part of the surface of the wooden substrate. I have.
As shown in FIG. 1 or FIG. 3, the light stabilizer holding surface 2 may be a surface in which HALS having a stable free radical is impregnated and held on the surface of the wooden substrate, as shown in FIG. It may be a layer in which HALS having a stable free radical is contained in a binder or the like and held.
As shown in FIG. 2, in the case where the binder or the like contains HALS having stable free radicals, the light stabilizer is retained even when the surface of the wooden substrate has large irregularities. It is possible to flatten the surface 2 by giving it thickness.
The binder used in the layer that contains and holds HALS having a stable free radical may be a solidified product of a resin composition other than a radical polymerization type curable resin that does not inhibit the polymerization reaction by HALS having a stable free radical. There are no particular restrictions. Examples of the solidified product of a resin other than the radical polymerization resin include a cured product of a non-radical curable resin composition and a solidified product of a non-curable resin composition.
Here, in the present invention, solidification means a general phenomenon in which fluidity is lost from a fluid state to a solid state, and the solidification is particularly high due to crosslinking reaction, polymerization reaction, etc. The phenomenon that becomes a solid state by molecularization is called curing.
Further, the solidified product of the resin composition refers to a resin composition that is a non-flowable solid, and excludes a resin composition that is in a liquid or semi-solid state, such as a low molecular weight, undried organic solvent. Moreover, in this invention, the hardened | cured material of a resin composition is a subordinate concept of the solidified product of a resin composition, and shows the resin composition which formed the three-dimensional polymer structure by the crosslinking reaction and the polymerization reaction.
Examples of the non-radical curable resin composition include moisture curable, cationic polymerization and anion polymerization resin compositions.
Examples of the moisture curable resin composition include moisture curable polyurethane and organopolysiloxane having an alkoxy group (curing by hydrolysis polycondensation reaction).
Examples of the cationic polymerization type curable resin composition and the anion polymerization type curable resin composition include thermosetting or photocurable epoxides.
Examples of the non-curable resin composition include a non-curable acrylic resin, a vinyl chloride-vinyl acetate copolymer, a non-curable urethane resin, a cellulose resin, or an acrylic resin and a vinyl chloride-vinyl acetate copolymer. A mixture of the above can be used.
Among them, the solidified resin composition other than the radical polymerization resin can be obtained by mixing a moisture-curable curable resin composition, a liquid containing an isocyanate-curable alkyd resin, and a liquid containing a curing agent. A cured product of the polyester resin composition is preferred.

HALS having a stable free radical refers to a compound having a stable free radical that has a strong action of capturing free radicals generated in the process of photooxidation of lignin and phenols, which are contained in a large amount of wood, among HALS.
Here, free radical is a term indicating atoms and molecules with unpaired electrons, and since it is usually highly reactive and unstable, it causes a redox reaction with other atoms and molecules and is stable. Molecules and ions. However, it is known that molecules with special structures form stable free radicals.
Free radicals generated in the process of photo-oxidation of lignin and phenols induce a chain radical reaction and thus have a great influence on the photodegradation of wood. A hindered amine is an amine having a steric hindrance structure, and a hindered amine light stabilizer having no stable free radical is radically decomposed by radicals generated in the process of photo-oxidation of lignin and phenols, resulting in free radicals. It is thought that the radical chain reaction is inhibited by becoming stable molecules and ions through the process of oxidization.
In HALS having stable free radicals used in the present invention, free radicals generated from the process of photooxidation from lignin and phenols are trapped by stable free radicals in a very short time after the generation, and become stable compounds. Inhibits chain radical reactions. HALS having a stable free radical itself undergoes radical decomposition and captures radicals generated in the process of photooxidation of lignin and phenols. As described above, it occurs in the process of photooxidation of lignin and phenols. It is thought that the action of scavenging radicals is extremely strong.
Examples of the HALS having a stable radical include 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl, Examples include 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl and 4-oxo-2,2,6,6-tetramethylpiperidine 1-oxyl.

  Although there is no restriction | limiting in particular in content of the hindered amine light stabilizer hold | maintained on a light stabilizer holding surface, In order to suppress discoloration of a wooden base material and to provide a weather resistance, the aqueous solution containing a density | concentration of 1-10 mass% Alternatively, it is preferable to treat the surface of the wood substrate using the composition.

(3) Isolation layer The woody member of the present invention has an isolation layer disposed between the light stabilizer holding surface and a protective layer made of a cured product of a radical polymerization type curable resin composition described later. The isolation layer has a function of completely blocking the transfer of the HALS having stable free radicals from the light stabilizer holding surface to the protective layer made of a cured product of the radical polymerization type curable resin composition, and the light stabilizer holding surface. And the function of ensuring the adhesion of the protective layer.
As shown in Fig. 1, because the surface of the wooden substrate is uneven, thickening the isolation layer completely blocks the transfer of HALS with stable free radicals from the light stabilizer holding surface to the protective layer. It becomes possible to do. Therefore, as shown in FIG. 1, the isolation layer may have a flattening function.
In addition, as shown in FIG. 2, when the surface of the layer 2 containing and holding the HALS having the stable free radicals is flattened, the stable free radicals can be obtained even if the isolation layer 3 is thinned to some extent. It is possible to completely block the HALS having a transition from the light stabilizer holding surface to the protective layer.
In addition, as shown in FIG. 3, HALS having stable free radicals can also be transferred from the light stabilizer holding surface to the protective layer by forming an isolation layer so as to follow the unevenness of the surface of the wooden substrate. It is possible to completely shut off. If the migration of HALS having stable free radicals can be completely blocked, the surface of the isolation layer is not necessarily flattened.

  As described above, in order for the isolation layer to exhibit the isolation function, the adhesion function, and the planarization function, it is necessary to form the isolation layer using a resin composition that is not inhibited by the stable free radicals of HALS. Therefore, a solidified product of a resin composition other than the radical curable resin is used. As the resin composition other than the radical curable resin, the same resin composition as the binder for the light stabilizer holding surface can be used.

  In addition, as long as the isolation layer can exhibit the above-mentioned function, there is no restriction | limiting in thickness, and it is so preferable that it is thin. Therefore, it is assumed that even if the woody member of the present invention is observed, it cannot be confirmed whether or not it has an isolation layer, but even in such a case, the HALS having the stable free radicals is not. A wood-based member having both a light stabilizer holding surface made of a holding surface and a protective layer made of a cured product of the radical polymerization type curable resin composition cannot be obtained without using an isolation layer. Therefore, if the wood-based member has both a light stabilizer holding surface consisting of a surface for holding HALS having stable free radicals and a protective layer consisting of a cured product of a radical polymerization type curable resin composition, an isolation layer is present. It is possible to judge.

The isolation layer may have a general HALS that does not have a stable free radical, or an ultraviolet absorber from the viewpoint of suppressing photoexcitation by ultraviolet rays on the surface of the wooden substrate and preventing photooxidation. It should be noted that even HALS that does not have stable free radicals or UV absorbers may move to the protective layer and weakly inhibit the curing reaction of the radical polymerization type resin, but have stable free radicals. Unlike HALS, it does not completely inhibit the curing reaction.
As ultraviolet absorbers, 2- (2-hydroxy-4-octoxyphenyl) -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- (2-hydroxy-4-hexyloxyphenyl) ) -4,6-diphenyl-s-triazine and other triazines, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-third In addition to organic ultraviolet absorbers such as benzotriazoles such as butylphenyl) -5-chlorobenzotriazole, benzophenones, and salicylic acid esters, particulate zinc oxide, cerium oxide, and titanium oxide having a particle size of 0.2 μm or less Inorganic ultraviolet absorbers such as these can also be used.
HALS having no stable free radicals include bis- (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis- (N-methyl-2,2,6,6-tetramethyl-4). -Piperidyl) sebacate and the like can be used.

(4) Protective layer In the woody member of the present invention, the light stabilizer holding surface is covered with a protective layer made of a cured product of a radical polymerization type curable resin composition via the isolation layer. The protective layer has a function of imparting durability (abrasion resistance, contamination resistance, strength, etc.) to the surface of the wooden member. In addition, in the wood-based member of the present invention that has been cured after applying the radical polymerization type curable resin composition to the wood substrate, it is easier to control the thickness than the wood member to which the formed film is attached, Since the amount of the combustible substance can be limited, it has a feature that it is excellent in flame retardancy and incombustibility.
In addition, the cured product of the radical polymerization type curable resin composition has higher scratch resistance and higher durability than the cured product of the non-radical polymerization type curable resin composition such as an alkyd resin. It has the characteristic that it is excellent in.
The resin used in the radical polymerization type curable resin composition is not particularly limited as long as it is a radical polymerization type resin. For example, ionizing radiation curable resins such as (meth) acrylate type, epoxy type, and polyester type, ( Examples thereof include thermosetting resins such as (meth) acrylate, urethane, epoxy, and polysiloxane. The ionizing radiation means electromagnetic waves or charged particles having energy that can be cured by polymerizing molecules. For example, all ultraviolet rays (UV-A, UV-B, UV-C), visible rays, gamma rays , X-ray, electron beam (EB) and the like.
Among these, an ionizing radiation curable radical polymerization resin is preferable, and an electron beam (EB) curable radical polymerization resin is more preferable.
The protective layer may have HALS which does not have a stable free radical, or an ultraviolet absorber from the viewpoint of suppressing photoexcitation due to ultraviolet rays on the surface of the wooden substrate and preventing photooxidation. As described above, even HALS that does not have stable free radicals or UV absorbers weakly inhibits the curing reaction of the above-mentioned radical polymerization type resin, but cures like HALS that has stable free radicals. It does not completely inhibit the reaction.
As HALS that does not have a stable free radical or an ultraviolet absorber, a compound similar to the compound exemplified in the isolation layer can be used.

(5) Other layers The woody member of the present invention may have other layers as necessary. As another layer, you may have a pattern layer which provides a desired pattern to a wood type member, for example. The pattern layer is usually a layer made of a resin containing a coloring component, and is formed by various known printing methods. Examples of resins include cellulose resins such as nitrocellulose (nitrified cotton), acetylcellulose, and sailulose acetate propionate, acrylic resins such as polymethyl (meth) acrylate and polybutyl (meth) acrylate, and vinyl chloride-vinyl acetate. A polymer, a copolymer of an acrylic resin and vinyl acetate, a mixture thereof, or the like can be used. Coloring components include organic pigments or dyes such as quinacridone red, polyazo red, isoindolinone yellow, nickel-azo complex, phthalocyanine blue, azomethine azo black pigment, perylene black pigment, petiole, vermilion red, cadmium red. Inorganic pigments such as titanium yellow, iron yellow, ultramarine blue, bitumen, cobalt blue, patina, iron black, carbon black, titanium white, zinc white, and antimony white can be used, but from the viewpoint of weather resistance, inorganic Pigments are preferred.
The pattern layer may be disposed between the wood light stabilizer holding surface and the isolation layer, or may be disposed between the isolation layer and the protective layer.

2. Production method of wood-based member of the present invention There is no particular limitation on the production method of the wood-based member of the present invention, but for example, it can be produced by the method exemplified below.
The wood-based member of the present invention comprises a step of preparing a wood substrate, a stabilizer holding surface forming step of holding a hindered amine light stabilizer having a stable free radical on at least a part of the surface of the wood substrate, the light stabilization Separation layer forming step for solidifying after applying a resin composition other than radical polymerization type curable resin on the agent holding surface, and protective layer formation for hardening after applying the radical polymerization type curable resin composition on the surface of the isolation layer It can be obtained by a production method comprising a process. Hereinafter, the example of the manufacturing method for obtaining the said woody-type member of this invention is demonstrated for every process.

(1) Process of preparing a wooden base material There is no restriction | limiting in particular in the wooden base material prepared in order to manufacture the wooden system member of this invention. As described above, wood that is easily discolored by photo-oxidation, such as cedar and straw, can have higher weather resistance than other wood. For preferred wood substrates: Since it has already been described in (1), the description is omitted here.

(2) Light stabilizer holding surface forming step In the light stabilizer holding surface forming step consisting of a surface for holding a hindered amine light stabilizer having a stable free radical, for example, as shown below, the surface of the wood substrate It may be formed by impregnating HALS having stable free radicals at least partially, or a layer in which HALS having stable free radicals is contained in a binder or the like may be formed.
For HALS having stable free radicals, 1. Since it has already been described in (2), the description is omitted here.

(2-1) When impregnated with HALS having stable free radicals on the surface of a wooden substrate When formed by impregnating HALS with stable free radicals, it is stable and free in a solvent that can be removed by drying, etc. After impregnating the wood substrate surface with a liquid in which HALS having radicals is dispersed or dissolved, the light stabilizer holding surface is formed by removing the solvent.
The solvent for dispersing or dissolving the HALS having stable free radicals is not particularly limited as long as it can be removed by drying or the like, and examples thereof include water, ethanol, and acetone.
The concentration of the solution in which HALS having stable free radicals are dispersed or dissolved is not particularly limited, but is preferably in the range of 1 to 10% by mass in view of the efficiency of removing the solvent.

(2-2) When forming a layer containing HALS having stable free radicals in a binder or the like on the surface of the wood substrate When forming a layer containing HALS having stable free radicals The raw material of the binder used for 1 is 1. Since it has already been described in (2), the description is omitted here.
For example, a resin composition in which HALS having stable free radicals is dispersed or dissolved is applied on a wooden substrate, and then cured or solidified to form a layer containing HALS having stable free radicals. Can do.
The composition may contain a removable solvent, a polymerization initiator and the like in addition to the binder raw material and HALS having stable free radicals, which are essential components.
The content of HALS having stable free radicals in the composition is preferably in the range of 1 to 10% by mass. Moreover, it is preferable that content of the binder in the said composition is the range of 5-30 mass%, and it is more preferable that it is the range of 10-20 mass%.
As mentioned above, if the surface of the wooden substrate is large, the layer holding the HALS containing stable free radicals in the binder or the like is thickened to completely cover the surface of the wooden substrate. Then, by flattening, the isolation layer can be thinned.
For example, when the surface roughness (Ra) of the wooden substrate is 20 μm, a layer containing HALS having stable free radicals in a state where a binder is applied, dried and solidified on the wooden substrate. The surface can be flattened by coating so that the film thickness becomes larger than the surface roughness value, preferably 1 μm or more and 21 μm or more.

(3) Isolation layer formation process In an isolation layer formation process, an isolation layer is formed on the said light stabilizer holding surface using resin compositions other than radical polymerization type curable resin.
As described above, in order to block the transfer of HALS having stable free radicals from the light stabilizer holding surface to the protective layer, it is necessary to completely isolate the light stabilizer holding surface and the protective layer by the isolation layer. .
First, when the wood substrate used is flat, or the surface of the wood substrate is completely covered with a layer containing HALS having a stable free radical in a binder or the like on the surface of the wood substrate. In the case of flattening, the coating amount in terms of solid content of the resin composition other than the radical polymerization type curable resin per 1 cm ² of the light stabilizer holding surface can be made relatively small. For example, the light stabilizer holding surface and the protective layer can be completely separated by the separating layer by setting the thickness of the solidified separating layer in the range of 2 μm or more. The film thickness of the solidified isolation layer is not limited only in terms of free radical isolation and shielding effects, but considering the applicability of the isolation layer, material costs, the design appearance of the resulting wood-based member, etc. It is not preferable to make the thickness more than the thickness at which the free radical sequestration effect is saturated, and it is usually sufficient that the thickness is about 5 to 10 μm at the maximum.
If the surface of the wooden substrate has large irregularities, or if it is not flattened by a layer containing HALS having a stable free radical in the binder or the like, the isolation layer is thickened or the wooden substrate It is necessary to completely separate the light stabilizer holding surface and the protective layer by forming the separating layer so as to follow the unevenness of the surface of the material.
For example, when forming the isolation layer so as to follow the irregularities on the surface of the wooden substrate, it can be coated in the same amount as when the wooden substrate used is flat, but radical polymerization type curing An appropriate viscosity may be imparted by preparing a composition of a resin composition other than the functional resin.
In addition, you may add normal HALS which does not have a stable free radical, or a ultraviolet absorber to resin compositions other than radical polymerization type curable resin.

(4) Protective layer forming step In the protective layer forming step, the isolation layer is formed by applying a radical polymerization type curable resin composition on the isolation layer and then curing it.
Regarding the raw material of the radical polymerization type curable resin composition, 1. Since it has already been described in (4), the description is omitted here.
In order to provide sufficient durability (scratch resistance, stain resistance, strength, etc.), the thickness of the protective layer after curing is 1 μm or more, preferably 3 μm or more, more preferably 10 μm or more. However, if it is too thick, the durability is saturated and the material cost is increased, so that it is usually 100 μm or less, and when no special durability is required, it is 50 μm or less, usually 20 μm or less.
The method of curing by radical polymerization is not particularly limited. When a thermosetting resin is used, it may be cured by heating. When an ionizing radiation curable resin is used, for example, all ultraviolet rays (UV -A, UV-B, UV-C), visible light, gamma ray, X-ray, electron beam (EB) may be applied for curing.
In particular, curing by electron beam (EB) irradiation shortens the time required for curing (shortening processing time) compared to curing by heat or ultraviolet irradiation, and it cures without problems even at room temperature. No photopolymerization initiator is required, and unnecessary photoreactive low molecular components do not remain in the cured product, so that low molecular components migrate to the surface during long-term use, causing changes in physical properties, or sunlight. This is preferable because there are advantages such as less concern about discoloration, and energy saving and solventless processing, which reduces environmental burden.
In addition, you may add normal HALS which does not have a free radical, or a ultraviolet absorber to a radical polymerization type curable resin composition.

  Since the wooden member of the present invention is excellent in weather resistance, for example, it is naturally suitable for interior wall materials and furniture such as building walls, floors, and ceilings, as well as outer walls, fences, roofs, door pockets, eaves ceilings, and verandas. And exterior materials for buildings such as clothes floors, snowboards, signboards, window frames, door frames, doors, handrails and other fittings and construction materials, interior materials for vehicles, trains, aircraft, ships, etc. Suitable for materials, outdoor desks and chairs.

1. Production of wood-based members [Example 1]
(1) Preparation of wood base material As a wood base material, a cedar board material (standard material) cedar board material whose surface center JIS B0601 (1994) default centerline average roughness Ra was adjusted to 10 μm was prepared.
(2) Formation of light stabilizer holding surface On the surface of the cedar board material, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (trade name; Lignostab (registered)) which is a HALS having a stable free radical (Trademark) aq, manufactured by BASF) was impregnated with a 3% by weight aqueous solution and dried to form a light stabilizer holding surface.
(3) Formation of isolation layer A film obtained by drying a non-radical polymerization type curable resin composition made of urethane acrylic polyol (trade name; EBR primer, manufactured by Dainichi Seika Kogyo Co., Ltd.) on the light stabilizer holding surface A separating layer was formed by coating and drying to a thickness of 12 μm, followed by curing at room temperature.
(4) Formation of protective layer An electron beam curable resin (trade name; EBF, manufactured by Dainichi Seika Kogyo Co., Ltd.) is applied on the isolation layer so that the film thickness after curing is 15 μm, and the oxygen concentration is 200 ppm. By using an electron beam irradiation apparatus in the following environment and curing under the conditions of irradiating an electron beam under the conditions of an acceleration voltage of 165 keV and 5 Mrad, a protective layer was formed, and a woody member of Example 1 was obtained.

[Comparative Example 1]
As in Example 1, except that the non-radical polymerization type curable resin composition was applied so that the film thickness after curing was 5 μm in (3) the step of forming the isolation layer in Example 1, A woody member of Comparative Example 1 was obtained.

[Comparative Example 2]
In Comparative Example 1, a woody member of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that (2) the step of forming the light stabilizer holding surface was not performed.

[Comparative Example 3]
In Example 1, (2) in the step of forming the light stabilizer holding surface, instead of HALS having a stable free radical, bis (2,2,6,6-) decanedioic acid bis (HALS) having no stable free radical is used. After impregnation in a 3% aqueous solution of tetramethyl-1- (octyloxy) -4-piperidinyl) ester, a water-soluble product of a reaction product of 1,1-dimethylethyl hydroperoxide and octane (trade name: Tinuvin 123DW, manufactured by BASF) A woody member of Comparative Example 3 was obtained in the same manner as Comparative Example 1 except that a light stabilizer holding surface having no stable free radicals was formed by drying.

2. Evaluation of wood-based members (1) Weather resistance discoloration test Samples were subjected to an ultra-accelerated weather resistance test apparatus (trade name; i Super UV Tester SUV-W261, manufactured by Iwasaki Electric Co., Ltd.), with illuminance of 100 mW / cm ² and back panel temperature of 63 ° C The cycle of performing water injection for 4 hours after irradiation for 20 hours under the above conditions was repeated for 100 hours. The pass / fail criterion was that the color difference between the samples before and after this test was ΔE ≦ 3.

(2) Scratch resistance test The rubbing process of the sample surface was performed 50 times with steel wool # 0000 under the condition of a load of 300 g / cm ² . The acceptance criteria were that the surface was not damaged before and after this test.

(3) Contamination resistance test The sample surface was written with office blue ink, an oily black marker, and a red crayon. After 2 hours, the sample was wiped with a detergent or a solvent. The acceptance criteria were that no color remained on the surface before and after this test.

(4) Adhesion test After the sample was cross-cut at 2 mm intervals, a peel test was performed with a 24 mm wide adhesive tape. The acceptance criteria were that there was no peeling before and after this test.

3. Evaluation results Table 1 summarizes the characteristics and evaluation results of the wood members of Example 1 and Comparative Examples 1 to 3.

As shown in Table 1, the non-radical polymerizable curable resin composition was applied on the light stabilizer holding surface, and the non-radical polymerizable curable resin was applied so that the thickness after curing was 5 μm. In the wood-based member, the radical polymerization type curable resin composition was not cured and a protective layer could not be formed.
Since the coating amount of the non-radical polymerization type curable resin composition on the light stabilizer holding surface is small, the light stabilizer holding surface is completely covered with the non-radical polymerization type curable resin composition (that is, the isolation layer is not covered). This is considered to be because HALS having stable free radicals migrated from the light stabilizer holding surface to the coating surface of the radical polymerization type curable resin composition.

In this regard, as shown in Table 1, Comparative Example 2 in which the light stabilizer holding surface was not formed at all on the surface of the wooden substrate, and the comparison in which the light stabilizer holding surface holding HALS having no stable free radical was formed. In the wooden member of Example 3, the protective layer was formed even when the coating amount of the non-radical polymerization type curable resin composition was the same as that of Comparative Example 1.
Even in Comparative Example 2 and Comparative Example 3, it is considered that, similarly to Comparative Example 1, it is impossible to completely cover the surface of the wood substrate with the non-radical polymerization type curable resin composition (that is, to form an isolation layer). This is considered to be because the radical polymerization type curable resin composition was cured without inhibiting radical polymerization because the light stabilizer holding surface did not have HALS having stable free radicals.
In the woody members of Comparative Example 2 and Comparative Example 3, since the protective layer was formed, there was no problem in the scratch resistance and stain resistance test, and the cured product of the non-radical polymerization type curable resin composition had an adhesion function. Since it plays the role of the primer layer to exhibit, there is also no problem in adhesion. However, since the light stabilizer holding surface composed of the surface holding HALS having stable free radicals is not provided, the light stabilizing action is weak, and the weather resistance discoloration evaluation is bad.

On the other hand, in the woody member of Example 1 in which the non-radical polymerizable curable resin composition was applied on the light stabilizer holding surface so that the coating amount was 12 μm, the radical polymerizable curable resin composition was The product was cured and a protective layer could be formed.
Since the coating amount of the non-radical polymerizable curable resin composition is an appropriate amount, the light stabilizer holding surface consisting of the surface holding HALS having stable free radicals is completely covered with the non-radical polymerizable curable resin composition. (I.e., forming an isolation layer), which prevents the HALS having stable free radicals from moving from the light stabilizer holding surface to the coated surface of the radical polymerization type curable resin composition. It is believed that there is.
A light stabilizer holding surface comprising a surface holding HALS having a stable free radical is provided, and the light stabilizer holding surface is interposed through an isolation layer made of a cured product of a non-radical polymerizable curable resin composition. The wood-based member of Example 1 coated with a protective layer made of a cured product of a radical polymerization type curable resin composition has no problem in the scratch resistance and stain resistance tests, and is non-radical polymerization type curability. Since the isolation layer made of a cured product of the resin composition exhibits an adhesion function, there is no problem with adhesion. Moreover, since it has the light stabilizer holding surface which consists of the surface holding HALS which has a stable free radical, the light stabilization action was strong and the weathering discoloration evaluation was also excellent.

  From the above results, at least a part of the surface of the wooden substrate has a light stabilizer holding surface composed of a surface holding a hindered amine light stabilizer having a stable free radical, and the light stabilizer holding surface is The wood-based member of the present invention, which is covered with a protective layer made of a cured product of a radical polymerization type curable resin composition, through an isolation layer made of a solidified product of a resin composition other than the radical polymerization type curable resin, It was revealed that it was excellent in weather resistance.

DESCRIPTION OF SYMBOLS 1 Woody base material 2 Light stabilizer holding surface 3 Separation layer 4 Protective layer 5 Primer layer 100 Wood-type member of this invention 200 Wood-type member of a prior art

Claims (3)

  At least a part of the surface of the wood substrate has a light stabilizer holding surface made of a surface holding a hindered amine light stabilizer having a stable free radical, and the light stabilizer holding surface is a radical polymerization curable. A wood-based member which is covered with a protective layer made of a cured product of a radical polymerization type curable resin composition via an isolation layer made of a solidified product of a resin composition other than a resin.   The hindered amine light stabilizer having a stable free radical is 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl. , 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl and at least one compound selected from the group consisting of 4-oxo-2,2,6,6-tetramethylpiperidine 1-oxyl The wood-based member according to claim 1, wherein   The woody member according to claim 1 or 2, wherein the radical polymerization type curable resin composition is an ionizing radiation curable radical polymerization type resin composition.