Surface preparation method, surface-prepared wood, and repainted wood

Abstract

To provide a base surface conditioning method capable of base conditioning without removing paint residue of painted wood, base surface conditioned wood, and repainted wood.SOLUTION: A base surface conditioning method includes: preparing a base surface conditioning agent containing a two component urethane; and applying the prepared base surface conditioning agent on coated wood. Base surface conditioned wood includes a first layer and a second layer present on a surface side of the first layer, where the second layer has a lower content of lignin constituting the wood than that of the first layer and contains resin. Repainted wood comprises the base surface conditioned wood and a paint deposit present on a surface of the base surface conditioned wood, where the surface is applied to base surface conditioning.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a surface conditioning method, surface-conditioned wood, and repainted wood, and in particular to a surface conditioning method, surface-conditioned wood, and repainted wood that are suitable for pretreatment of wood for repainting. [Background technology]

[0002] In general, wooden and iron parts of buildings exposed to the outdoors are painted to improve their appearance or to protect them from sunlight, wind and rain. Painted parts are repainted at appropriate times to maintain their functionality. When repainting, the existing paint film (old paint film) is sometimes removed by physical removal such as scraping or blasting, or chemical removal using a stripping agent, and then new paint is applied (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4852170 Summary of the Invention [Problem to be solved by the invention]

[0004] However, scraping and blasting may generate dust and noise, while the use of a stripping agent may contain environmentally undesirable substances, which may require time and cost to collect and dispose of the used stripping agent.

[0005] In view of the above-mentioned problems, the present disclosure relates to providing a surface preparation method that enables surface preparation of painted wood without removing paint residue from the painted wood, surface-prepared wood, and repainted wood that has been repainted after surface-prepared wood has been provided. [Means for solving the problem]

[0006] A surface conditioning method according to a first aspect of the present disclosure includes the steps of preparing a surface conditioning agent containing a two-component urethane, and applying the prepared surface conditioning agent onto painted wood.

[0007] In this way, the surface of the wood can be adjusted without removing the paint residue. By adjusting the surface of the wood, the deteriorated layer of the wood can typically be reinforced. The paint residue typically corresponds to the coating film when the paint is a film-forming or semi-film-forming paint, and to the pigments and the like remaining after the paint has penetrated the wood and the volatile components have volatilized when the paint is an impregnation paint. Depending on the situation, the surface adjustment method according to the first aspect of the present disclosure may also include a step of preparing a surface adjuster containing a two-component urethane and a diluent, and a step of applying the prepared surface adjuster onto the painted wood.

[0008] In addition, a surface preparation method according to a second aspect of the present disclosure is a surface preparation method according to the first aspect of the present disclosure, in which the painted wood is wood on whose surface a film-forming or semi-film-forming paint has been applied at least once to form a coating film.

[0009] In this way, if a coating film is present, both the coating film and the deteriorated layer of wood that was present below the coating film can be reinforced with urethane resin, and if the coating film is no longer present, the deteriorated layer of wood that was present below the coating film that was previously present can be reinforced with urethane resin.

[0010] A surface conditioning method according to a third aspect of the present disclosure is the surface conditioning method according to the first or second aspect of the present disclosure, wherein the surface conditioning agent contains an organic solvent.

[0011] This configuration allows the two-component urethane to easily penetrate paint residue and wood, making it easier for the urethane to reach deteriorated layers of the wood.

[0012] A surface preparation method according to a fourth aspect of the present disclosure is a surface preparation method according to any one of the first to third aspects of the present disclosure, wherein the two-component urethane contains a base agent and a hardener, and the weight ratio of the base agent to the hardener is 0.8 or more and 3.0 or less.

[0013] With this configuration, the reinforcement of the deteriorated layer of the wood by the urethane resin can be made stronger.

[0014] Furthermore, a surface preparation method according to a fifth aspect of the present disclosure is a surface preparation method according to any one of the first to fourth aspects of the present disclosure, wherein the surface preparation agent includes a diluent, and the weight ratio of the diluent to the two-component urethane is 0.1 or more and 2.0 or less.

[0015] This reduces the viscosity of the surface conditioner, improving its penetration into the wood and softening any residual paint. It also makes it easier to remove any excess surface conditioner that was not absorbed by the wood and remains on the surface of the wood, making it easier to paint after surface conditioning.

[0016] Furthermore, a surface preparation method according to a sixth aspect of the present disclosure is a surface preparation method according to any one of the first to fifth aspects of the present disclosure, further comprising a step of applying a surface colorant onto the painted wood before applying the surface preparation agent onto the painted wood.

[0017] In this way, it is possible to carry out surface preparation for the painted wood in order to bring out the color of the topcoat that will be applied later as a repaint.

[0018] A base material adjusting method according to a seventh aspect of the present disclosure is the base material adjusting method according to any one of the first to sixth aspects of the present disclosure, wherein the base material adjusting agent includes a base material colorant.

[0019] In this way, it is possible to adjust the base of the painted wood in order to bring out the color of the topcoat that will be applied later as a repaint.

[0020] Furthermore, the surface-prepared wood according to the eighth aspect of the present disclosure is wood having a surface preparation agent containing a two-component urethane applied onto painted wood, and the surface preparation method according to any one of the first to seventh aspects of the present disclosure is applied thereto.

[0021] In this way, it is possible to obtain wood that has been subjected to surface preparation without removing paint residue. Depending on the circumstances, the surface-prepared wood according to the eighth aspect of the present disclosure may be wood that has been painted and has been coated with a surface preparation agent containing a two-component urethane and a diluent, and that has been subjected to the surface preparation method according to any one of the first to seventh aspects of the present disclosure.

[0022] A surface-conditioned wood according to a ninth aspect of the present disclosure comprises a first layer and a second layer located closer to the surface than the first layer, the second layer having a lower content of lignin constituting wood than the first layer and containing resin. The surface-conditioned wood according to the ninth aspect may have the same structure as the surface-conditioned wood according to the eighth aspect of the present disclosure.

[0023] By configuring in this manner, a surface-conditioned wood material is obtained in which a layer that was once deteriorated has been reinforced with resin.

[0024] Furthermore, the surface-conditioned wood material according to a tenth aspect of the present disclosure is the surface-conditioned wood material according to the ninth aspect of the present disclosure, which comprises paint residue on at least the surface of the second layer.

[0025] By configuring in this manner, it is possible to obtain surface-conditioned wood in which both the paint residue and the deteriorated layer of wood that was present underneath the paint residue are reinforced with resin.

[0026] In addition, the surface-conditioned wood according to an eleventh aspect of the present disclosure is the surface-conditioned wood according to the ninth or tenth aspect of the present disclosure, which further comprises a surface colorant at least on the surface side of the second layer.

[0027] By configuring in this manner, it is possible to obtain surface-conditioned wood material in which the surface has been conditioned to bring out the color of the topcoat paint to be applied later as a repaint.

[0028] In addition, repainted wood in a twelfth aspect of the present disclosure comprises surface-conditioned wood in any one of the eighth to eleventh aspects of the present disclosure and a paint fixative present on the surface of the surface-conditioned wood where the surface conditioning has been performed.

[0029] With this configuration, a piece of wood can be easily obtained by repainting a piece of wood that has already been painted. Effect of the Invention

[0030] According to the present disclosure, it is possible to prepare the surface of wood without removing paint residue. [Brief description of the drawings]

[0031] [Figure 1] 3 is a flowchart showing the procedure of a surface preparation method according to the first embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view of a surface-conditioned wood material according to a first embodiment. [Diagram 3] FIG. 2 is a micrograph of wood having a deteriorated layer. [Figure 4] FIG. 2 is a schematic cross-sectional view of a repainted wood piece according to the first embodiment. [Diagram 5] 10 is a flowchart showing the procedure of a surface preparation method according to a second embodiment. [Figure 6] FIG. 4 is a schematic cross-sectional view of a surface-prepared wood piece according to a second embodiment. [Figure 7] FIG. 2 is a schematic diagram illustrating the procedure of an adhesion test. [Figure 8]FIG. 2 is a micrograph of wood whose surface has been adjusted using the surface adjustment method according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, an embodiment will be described. In this embodiment, a method for easily performing surface preparation on wood that has already been painted (painted wood), wood that has been subjected to surface preparation, and wood that has been repainted are disclosed. In this embodiment, "surface preparation" means preparation of the surface (base) to be repainted before repainting. Painted wood includes wood that has been painted in the past and has subsequently deteriorated. In the following description, "paint residue" refers to paint residue on painted wood, typically remaining after volatile components have volatilized from the paint applied to the surface of the wood. Furthermore, "fixed paint" refers to paint components that have been fixed after repainting on wood that has been subjected to surface preparation, typically remaining after volatile components have volatilized from the paint applied to the surface of wood that has been subjected to surface preparation. In wooden buildings, such as log houses, wood is used not only for pillars and beams but also for exterior walls. Types of wood used in log houses include redwood, spruce, North American pine, Nordic pine, Douglas fir, Western red cedar, cedar, Western larch, cypress, and Japanese larch. Buildings that use wood for the exterior walls have parts of the wood that are exposed to the outdoors. Wood exposed to the outdoors is exposed to sunlight, wind, and rain. Wood exposed to the outdoors is generally painted to protect it from sunlight, wind, and rain.

[0033] Paints applied to wood are roughly divided into film-forming and impregnating types. Film-forming paints create a film on the surface of the applied wood, and the film protects the wood from sunlight, wind, rain, and the like. Film-forming paints typically create a film on the surface of the wood without penetrating the wood. Film-forming paints range from transparent to colored, and the stronger the coloring, the less the texture of the wood remains, but the higher the weather resistance tends to be. A specific example of a film-forming paint is Nonrot Bruno (registered trademark) manufactured by Mitsui Chemical Industrial Products Co., Ltd. On the other hand, impregnating paints penetrate from the surface of the applied wood to the inside, and exert a protective effect from the inside of the wood. Impregnating paints include transparent ones as well as semi-transparent ones that are colored while retaining the texture of the wood, and the more strongly colored they are, the higher the weather resistance is. A specific example of an impregnating paint is Xyladecor (registered trademark) manufactured by Osaka Gas Chemicals Co., Ltd. Comparing film-forming and impregnation types, film-forming paints have higher weather resistance than impregnation types. There are also semi-film-forming paints that are intermediate between film-forming and impregnation types. Semi-film-forming paints form a thin film on the surface of the wood they are applied to while penetrating into the wood. In general, the film formed on the surface of wood by semi-film-forming paints is thinner than the film formed by film-forming paints. A specific example of a semi-film-forming paint is Semi-Opaque (registered trademark) manufactured by Mitsui Chemical Industrial Products, Inc.

[0034] Both film-forming (including semi-film-forming) paints and impregnating paints deteriorate over time when applied to wood exposed to the outdoors, so they are repainted at appropriate times. In general, impregnating paints are repainted more frequently than film-forming paints. The inventors have found that when repainting wood, if paint residues remain and are painted over the paint residues, the paint fixation product of the new paint is likely to peel off. This is thought to be because the wood at the interface between the paint residues and the wood deteriorates over time, and even if new paint is applied over the paint residues, the paint fixation product and the paint residue will peel off from the deteriorated area. When film-forming paints are used, the frequency of repainting can be relatively low, but the film (hereinafter referred to as the "old paint film"), which is the paint residue formed on the surface of the wood, is often easily peeled off due to deterioration over time. In order to prevent the new paint film (paint fixation product) from peeling off together with the old paint film, it is considered to remove the old paint film before repainting. However, when the old coating film is physically removed by scraping or blanching, it is preferable to avoid this because it may generate dust and noise. On the other hand, when the old coating film is chemically removed by using a stripping agent, it is preferable to avoid this from the viewpoint of reducing the processing burden because the stripping agent contains methylene chloride, which must be collected and disposed of after use. Therefore, in the first embodiment described below, a case where the painted wood is wood coated with a film-forming or semi-film-forming paint is exemplified, and a method of preparing the base of the painted surface to suppress peeling off of the old coating film without removing it is disclosed.

[0035] FIG. 1 is a flow chart showing the procedure of the surface preparation method according to the first embodiment. In the surface preparation method according to the first embodiment, a specific surface preparation agent containing a two-liquid urethane is prepared, and the surface preparation agent is applied to an old coating film to reinforce the deteriorated layer of the wood, and when the wood is repainted later, a newly applied paint film is appropriately formed. The wood (painted wood) to which the surface preparation method according to the first embodiment is applied is typically wood on which a film-forming or semi-film-forming paint has been applied to the surface and on which an old coating film has been formed, and is wood that has been exposed to the outdoors for a predetermined period of time. The predetermined period here is typically a period during which deterioration of the old coating film becomes visible, and is generally longer for wood on which a colored paint film has been formed than for wood on which a clear paint film has been formed. The predetermined period is often about 5 to 10 years, but may be shorter than 5 years, for example 1 to 3 years or less, or longer than 10 years, for example 12 to 13 years or more, depending on various conditions. The deterioration of the old coating film appears as cracks in the coating film due to the influence of ultraviolet rays, and generally also accompanies the deterioration of the wood surface underneath the old coating film. When starting such wood base preparation, first mix two-component urethane (S1). Two-component urethane is obtained by reacting a base agent containing various polyols with a curing agent containing various isocyanates to obtain a urethane resin.

[0036] Examples of polyols contained in the base material of two-component urethane include acrylic polyol, polyester polyol, alkyd polyol, polyether polyol, fluorine-containing polyol, epoxy polyol, etc. Other examples of substances contained in the base material include propylene glycol monomethyl ether acetate, a mixture of ethyl acetate, methyl isobutyl ketone, and normal butyl acetate, etc.

[0037] Examples of isocyanates contained in two-component urethane hardeners include tolylene diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, isophorone diisocyanate, methylene diphenyl diisocyanate, etc. Other examples of substances contained in hardeners include a mixture of ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and hexamethylene diisocyanate, or a mixture of tolylene diisocyanate, ethyl acetate, and normal butyl acetate, etc.

[0038] When mixing two-component urethane, the weight ratio of the base agent to the hardener (weight of the base agent / weight of the hardener) is preferably 0.8 to 3.0 depending on the type of substance contained. The weight ratio of the base agent to the hardener is appropriately determined depending on the type of substance contained as described above, but it is more preferable to set it to 1.0 or more from the viewpoint of suppressing excess hardener, and more preferable to set it to 2.0 or less from the viewpoint of improving strength by crosslinking.

[0039] After mixing the two-component urethane, the two-component urethane and diluent are mixed together (S2). The diluent is mixed into the two-component urethane to make it easier to spread the two-component urethane on wood. The two-component urethane and diluent are mixed together to produce a surface conditioner to be applied to wood. Typically, an organic solvent such as urethane thinner is used as the diluent. Examples of this type of organic solvent include ethyl acetate, butyl acetate, and mixtures thereof. A surface conditioner that uses an organic solvent as a diluent is referred to as a solvent-type surface conditioner. When mixing the two-component urethane and diluent, the weight ratio of the diluent to the two-component urethane (weight of diluent / weight of two-component urethane) is preferably 0.1 to 2.0, and is preferably 0.5 or more in order to prevent the diluent from volatilizing too quickly. The step (S2) of mixing the two-component urethane and the diluent includes both pouring the diluent into the previously prepared mixed two-component urethane and pouring the mixed two-component urethane into the previously prepared diluent. In the example shown in Fig. 1, the mixed two-component urethane and the diluent are mixed (S2) after the step (S1) of mixing the two-component urethane, but these steps (S1, S2) may be performed simultaneously depending on the ingredients of the two-component urethane, etc. In other words, the main agent constituting the two-component urethane, the hardener constituting the two-component urethane, and the diluent may be mixed simultaneously.

[0040] Once the surface conditioner is produced, it is applied to the portion of the wood to be repainted (S3). At this time, simple cleaning such as removing dust may be performed. In this embodiment, it is not necessary to remove the old coating film, but if it is desired to remove the old coating film, it is acceptable to remove a part or all of the old coating film. The surface conditioner is applied from above the old coating film and / or from above the area where the detached old coating film was present, in other words, from above the paint residue. After the surface conditioner is applied, it is determined whether a predetermined time has passed since application (S4). The predetermined time here is preferably at least the time required for the applied surface conditioner to penetrate the old coating film and reach the wood under the old coating film, and more preferably the time required for the applied surface conditioner to penetrate (permeate) the deteriorated layer of the wood under the old coating film. The predetermined time depends on the ingredients of the surface conditioner, but may be, for example, several minutes to 24 hours. In this embodiment, an organic solvent is used as a diluent contained in the surface conditioner, so that the surface conditioner can be allowed to soak into the old coating film at the appropriate time.

[0041] In the step (S4) of determining whether a predetermined time has elapsed since the surface conditioner was applied to the wood, if the predetermined time has not elapsed, the process returns to the step (S4) of determining whether the predetermined time has elapsed. On the other hand, if the predetermined time has elapsed, the surface conditioner remaining on the old coating is wiped off (S5). If repainting is performed on the surface conditioner that still remains, the paint for repainting may be repelled, and the paint may not adhere well. For this reason, it is preferable to wipe off the surface conditioner so that the excess surface conditioner (not penetrating under the old coating) can be properly removed. In other words, it is preferable to determine the amount of diluent to be injected in the step (S2) of mixing the two-component urethane and the diluent so that the surface conditioner is not dried when a predetermined time has elapsed since the surface conditioner was applied to the wood. By injecting a relatively large amount of diluent into the two-component urethane, the time it takes for the surface conditioner to dry can be delayed, so that the two-component urethane can have time to penetrate into the deteriorated layer of the wood under the old coating. In addition, by delaying the drying of the surface conditioner, the excess surface conditioner remaining on the old coating can be properly wiped off. By properly wiping off the excess surface conditioner, it is possible to prevent the paint from adhering poorly when repainting after the surface conditioner is prepared. In addition, if the deterioration of the painted wood progresses quickly and the amount of the applied surface conditioner absorbed is large, the two-component urethane will sufficiently penetrate into the deteriorated layer of the wood under the old coating, so that there may be cases where the undried surface conditioner is not present on the surface. In this case, the step (S5) of wiping off the excess surface conditioner can be omitted (step (S5) does not need to be performed).

[0042] After wiping off the excess surface conditioner, it is determined whether or not the waiting time has elapsed (S6). Here, the waiting time is the time required for the two-component urethane that has spread to the deteriorated layer of the wood beneath the old coating to harden. The waiting time may vary depending on factors such as the ingredients of the two-component urethane, but it is recommended that at least 2 hours to 1 day be secured. If the waiting time has not elapsed in the step (S6) of determining whether or not the waiting time has elapsed, the process returns to the step (S6) of determining whether or not the waiting time has elapsed. On the other hand, when the waiting time has elapsed, a wood material that is ready for repainting and has undergone surface conditioning can be obtained, and the surface conditioning method is terminated. At this time, the wood material that has undergone surface conditioning (surface-conditioned wood material) is as follows:

[0043] FIG. 2 is a schematic cross-sectional view of a surface-conditioned wood 1. In FIG. 2, the upper side of the paper is the part exposed to the outdoors, that is, the surface side. FIG. 2 is a schematic diagram, and the ratio of the size of each part does not represent the actual ratio. Surface-conditioned wood 1 is an example of wood that has been deteriorated over time by applying a film-forming or semi-film-forming paint to the surface to form a coating film, and has been subjected to surface conditioning, and has a base layer 3, a resin mixed layer 5, and an old coating film 7. In general, wood is mainly composed of cellulose, hemicellulose, and lignin. Cellulose is a polymer in which glucose is bonded in a linear chain, and constitutes wood fibers. Hemicellulose is a polymer in which sugars other than glucose are bonded, and constitutes wood fibers together with cellulose. Lignin is an aromatic polymer compound that strongly binds cellulose and hemicellulose, which constitute wood fibers, and also fixes cell walls to each other. In the surface layer of wood exposed to the outdoors, mainly lignin absorbs ultraviolet rays contained in sunlight and is decomposed by radical reactions to become low molecular weight. The layer in which mainly lignin in wood is decomposed by ultraviolet rays becomes the deteriorated layer. For example, the content of lignin in undegraded wood is about 20% by weight to 35% by weight for softwood and about 17% by weight to 28% by weight for hardwood in temperate zone wood, whereas the content of lignin in the deteriorated layer is thought to be about 8% by weight to 15% by weight less than that of undegraded wood. The presence of undegraded and deteriorated layers in wood can be confirmed, for example, by infrared spectroscopy. FIG. 3 shows a micrograph of wood having a deteriorated layer 9. In the deteriorated layer 9, it can be observed that the lignin in the wood has been leached out, leaving cellulose and / or hemicellulose fibers in a cotton-like state. In FIG. 3, the same elements as those shown in FIG. 2 are given the same reference numerals.

[0044] Referring again to FIG. 2, the base layer 3 constituting the surface-conditioned wood 1 is a layer in which the lignin in the wood is not substantially decomposed by ultraviolet light and is not deteriorated, and corresponds to the first layer. The base layer 3 typically has a lignin ratio of about 17% by weight to 35% by weight among the components constituting the base layer 3. The resin-mixed layer 5 is a layer in which a resin (urethane resin in this embodiment) is inserted into the deteriorated layer 9 (see FIG. 3) from which the lignin has leached out. The resin-mixed layer 5 has a lower lignin content than the base layer 3 and contains a resin that is not contained in the base layer 3, and corresponds to the second layer. The resin-mixed layer 5 typically has a lignin content reduced by about 8% by weight compared to the content in the base layer 3, and may be reduced by 10% by weight or more, or may be reduced by 12% by weight or more. It is considered that in the resin-mixed layer 5, this resin, instead of lignin, binds cellulose and / or hemicellulose fibers. In other words, the resin-mixed layer 5 can be considered to be a layer in which at least a portion of the lignin in the base material layer 3 has been replaced with resin. In the surface-conditioned wood 1 according to this embodiment, the resin-mixed layer 5 is located on the surface of the base material layer 3. The resin-mixed layer 5 may be provided on the entire surface of the surface-conditioned wood 1, or may be provided on only a portion of the surface. As described above, the old paint film 7 is a paint film formed by applying a film-forming or semi-film-forming paint to the surface of the wood, and corresponds to paint residue.

[0045] In the surface-conditioned wood 1, the two-component urethane that has spread to the deteriorated layer of the wood under the old coating film 7 has hardened by applying the above-mentioned surface conditioning method, and the deteriorated layer of the wood has become a resin-mixed layer 5 that is reinforced by urethane bonds generated by the reaction of the two-component urethane. The resin-mixed layer 5 tends to be relatively thin where the old coating film 7 remains, and relatively thick where the old coating film 7 is gone. In addition, the resin-mixed layer 5 and the old coating film 7 that has been soaked with the surface conditioning agent are adhered to each other by urethane bonds, so that the old coating film 7 does not peel off from the resin-mixed layer 5. In addition, as described above, the excess surface conditioning agent on the old coating film 7 has already been removed. The presence of the base layer 3, the resin-mixed layer 5, and the old coating film 7 in the surface-conditioned wood 1 in this state can be confirmed by, for example, infrared spectroscopy. For example, the old coating film 7 of the surface-conditioned wood 1 is scraped off using a microtome, and infrared spectroscopy is performed on the layer that appears to confirm the urethane peak, thereby identifying the presence of the resin-mixed layer 5. When a paint for repainting is applied to the surface-prepared wood 1 in such a state over the old paint film, the paint film (fixed paint) generated by the repainting will adhere appropriately to the surface-prepared wood 1. FIG. 4 shows an example of a repainted wood 10 generated by repainting the surface-prepared wood 1. The repainted wood 10 has a new paint film 17 formed by repainting on the surface of the surface-prepared wood 1. The new paint film 17 is a form of paint residue after volatile components have volatilized from the repainted paint, and corresponds to a fixed paint film. In the surface-prepared wood 1, the old paint film 7 may be peeled off for some reason, and part or all of the old paint film 7 may not exist. In the examples shown in FIG. 2 and FIG. 4, part of the old paint film 7 is peeled off. Even if the old paint film 7 does not exist in the surface-prepared wood 1, the surface preparation has been performed because the urethane resin has hardened in the deteriorated layer of the wood.

[0046] As described above, according to the surface conditioning method of the first embodiment, the surface conditioning agent penetrates into the old coating film and reaches the deteriorated layer of the wood, so that the surface conditioning agent can be applied to the wood to perform surface conditioning of the wood without removing the old coating film. In addition, the two-liquid urethane of the surface conditioning agent that reaches the deteriorated layer of the wood hardens in the deteriorated layer, so that the deteriorated layer of the wood can be reinforced. In other words, the urethane penetrates under the paint residue of the painted wood to reinforce the wood. In addition, according to the surface-conditioned wood of this embodiment, the deteriorated layer and the old coating film of the wood are reinforced by the urethane resin, so that the wood suitable for repainting can be obtained. In addition, according to the repainted wood of this embodiment, since the above-mentioned surface-conditioned wood is repainted, peeling off of the old coating film can be suppressed, and wood protected by repainting can be easily obtained.

[0047] In the above explanation, the wood to which the surface preparation method shown in Fig. 1 is applied is wood that has been coated with a film-forming or semi-film-forming paint, but the method may also be applied to wood that has been coated with an impregnating paint. However, if the above-mentioned surface preparation method is applied to wood that has been coated with an impregnating paint, when the wood is repeatedly repainted with the same color after the surface preparation, or when a color different from the original color (especially a light color) is used as the paint for the repainting, the expected color may not be obtained, or the color may not be uniform. The reasons for this are thought to be one or more of the following: when repainting is performed over time, as the wood deteriorates, black mold may grow and the wood may turn black; wood that has been coated with an impregnating paint and has been surface-prepared without an old paint film absorbs more paint than undeteriorated wood, so the finished color becomes darker and a little darker; and when a paint of a color different from the original color (especially a light color) is applied during repainting, the original color may show through. For these reasons, even if a paint of the same color as the original or a different color (especially a light color) is applied after surface preparation, it is difficult to produce the expected color or a uniform color. In other words, it is difficult to produce the color of the repainted (topcoat) paint by painting a new coat after surface preparation on wood that has been coated with an impregnating paint. Therefore, in the second embodiment described below, a case is exemplified where the painted wood is coated with an impregnating paint, and a method of surface preparation of a painted surface that makes it possible to produce the color of the topcoat paint for repainting is disclosed.

[0048] FIG. 5 is a flow chart showing the procedure of the surface preparation method according to the second embodiment. In the surface preparation method according to the second embodiment, a specific surface preparation agent containing two-liquid urethane is prepared as in the first embodiment, but a surface coloring agent is applied to the painted wood before the surface preparation agent is applied to the painted wood, thereby reinforcing the deteriorated layer of the wood while enabling the surface preparation to bring out the color of the topcoat paint when repainting later. Here, the "substrate coloring agent" is a coloring agent for coloring the surface (base) to be repainted, and is typically a general term for pigments and dyes. In addition, in this embodiment, a substance that dissolves in a solvent such as water or oil is called a "dye," and a substance that does not dissolve in a solvent is called a "pigment." When a pigment is put into a solvent, it is dispersed and present in the solvent.

[0049] The wood (painted wood) to which the surface preparation method according to the second embodiment is applied is typically wood that has been coated with an impregnating paint on its surface and that has been exposed to the outdoors for a certain period of time. The certain period here is typically the period during which deterioration of the wood is observed, and is generally 3 to 7 years in most cases, but may be shorter than 3 years, for example, 1 to 2 years or less, or longer than 7 years, for example, 8 to 10 years or more, depending on various conditions. Such deterioration of wood is accompanied by deterioration of the wood surface due to, for example, biological deterioration due to mold or algae, or the influence of ultraviolet rays. When the surface preparation of such wood is started, first, a two-component urethane is mixed (S11). The two-component urethane is typically the same as that used in the first embodiment. In this embodiment, the two-component urethane is not diluted with a diluent, and the two-component urethane itself is used as the surface preparation agent. The reason for this is that since the surface preparation agent is easily permeated into the wood that has been coated with an impregnating paint because there is no old coating film, the surface preparation agent is prevented from permeating too much. However, depending on the number of times that impregnating paint has been applied to the painted wood, old paint films may still be present on the painted wood. In this case, two-component urethane diluted with a thinner can be used as a surface conditioner.

[0050] After mixing the two-part urethane, a base colorant is applied to the portion of the wood to be repainted before applying the two-part urethane (S12). At this time, simple cleaning such as removing dust may be performed. The base colorant may be applied over the paint residue. In this embodiment, a pigment is used as the base colorant. In addition, in order to facilitate application of the base colorant to the painted wood, in this embodiment, the base colorant is mixed with a dispersant and applied. As the dispersant, typically, an organic solvent such as thinner can be used, but a water-based dispersant may also be used. After the base colorant is applied, it is determined whether a predetermined time has passed since the application of the base colorant (S13). The predetermined time here is preferably the time required for the dispersant mixed with the base colorant to thoroughly evaporate and for the surface of the wood to which the base colorant has been applied to dry, and may be, for example, several minutes to 24 hours, although it depends on the components of the dispersant. In the example shown in Fig. 5, for convenience of explanation, the two-component urethane is mixed first (S11) and then the base colorant is applied (S12), but the mixing of the two-component urethane (S11) and the application of the base colorant (S12) may be performed simultaneously, or the order may be reversed. In particular, when the above-mentioned predetermined time is longer than the time required to mix the two-component urethane, it is preferable to apply the base colorant first (S12) and then mix the two-component urethane (S11). In this case, the time may be adjusted so that the mixing of the two-component urethane is completed about the time that the predetermined time has elapsed since the application of the base colorant.

[0051] In the step (S13) of determining whether a predetermined time has elapsed since the application of the surface colorant to the wood, if the predetermined time has not elapsed, the process returns to the step (S13) of determining whether the predetermined time has elapsed. On the other hand, if the predetermined time has elapsed, a surface conditioner is applied over the applied surface colorant (S14). This surface conditioner application step (S14) and the subsequent steps (S15-S17) are basically the same as the surface conditioner application step (S3) and the subsequent steps (S4-S6) in the first embodiment shown in FIG. 1. However, in this embodiment, taking into consideration the fact that the surface conditioner does not contain a diluent and that no old coating film exists on the wood, it is preferable that the predetermined time in the step (S15) of determining whether a predetermined time has elapsed since the application of the surface conditioner is at least the time required for the applied surface conditioner to penetrate into the surface colorant and reach the wood beneath the surface colorant. The applied surface colorant is considered to be layered due to drying, but since there are gaps between the pigment particles of the surface colorant, the surface conditioner is considered to penetrate more easily than the old coating film (see FIG. 2). The predetermined time depends on the components of the surface conditioner, but may be, for example, several minutes to 24 hours. In addition, in the step (S16) of wiping off the excess surface conditioner, the surface conditioner remaining on the surface colorant is wiped off. In this way, in the steps (S14) to (S17) of this embodiment shown in FIG. 5, the old coating film in the explanation of the steps (S3) to (S6) of the first embodiment shown in FIG. 1 may be read as the surface colorant. Note that, in this embodiment as well, if there is no undried surface conditioner on the surface when a predetermined time has passed since the surface conditioner was applied to the wood, the step (S16) of wiping off the excess surface conditioner can be omitted. In particular, wood that has been coated with an impregnating paint tends to absorb a greater amount of applied surface conditioner than wood that has been coated with a film-forming or semi-film-forming paint, so it is estimated that there are many cases where it is not necessary to perform step (S16) of wiping off excess surface conditioner. If step (S16) is omitted, it is sufficient to proceed to step (S17) when a predetermined time has elapsed in step (S15).In this embodiment in which the surface preparation method is applied as described above, wood that has undergone surface preparation (surface-prepared wood) is as follows.

[0052] FIG. 6 is a schematic cross-sectional view of a surface-conditioned wood 2. In FIG. 6, the upper side of the paper is the part exposed to the outdoors, that is, the surface side. FIG. 6 is a schematic view, and the ratio of the size of each part does not represent the actual ratio. Surface-conditioned wood 2, which is produced by surface conditioning wood that has been coated with an impregnating paint, has a base layer 3 and a resin mixed layer 5, but typically does not have a previous coating film 7 (see FIG. 2), as compared with surface-conditioned wood 1 (see FIG. 2), which is produced by surface conditioning wood that has been coated with a film-forming or semi-film-forming paint. Surface-conditioned wood 2 has a colorant layer 8 instead of the previous coating film 7 (see FIG. 2). The colorant layer 8 is mainly a layer of the surface colorant that was applied in the above-mentioned surface conditioning method and remained in a layer form due to the evaporation of the dispersant. The resin mixed layer 5 of the surface-conditioned wood 2 is mainly formed by applying the above-mentioned surface conditioning method, when the surface conditioning agent is applied on top of the dried surface colorant applied to the wood, the applied surface conditioning agent penetrates the surface colorant, and the two-component urethane that has spread to the deteriorated layer of the wood below the surface colorant hardens and is reinforced. Since the surface colorant in this embodiment uses a pigment, it is considered that the surface conditioning agent typically reaches the deteriorated layer of the wood through the gaps between the pigment particles, and many of the pigment particles tend to remain on the surface of the wood. In FIG. 6, for convenience, the colorant layer 8 is shown adjacent to the resin mixed layer 5, but in reality, it is considered that the pigment particles and the two-component urethane particles mix and solidify together, with more pigment particles present at the top and more two-component urethane present at the bottom. Since many of the pigment particles are present on the surface of the surface-conditioned wood 2, the color of the pigment remains on the surface of the surface-conditioned wood 2, making it possible to change the color when a light-colored paint is applied after the surface conditioning. In this way, the resin mixed layer 5 and the colorant layer 8 of the surface-adjusted wood 2 have the function of separating the topcoat paint for repainting from the painted wood (the function of preventing the color transfer of the base colorant to the topcoat paint). In contrast, if a topcoat paint for repainting (new paint) is applied directly on top of the base colorant without applying a surface adjustment agent, the base colorant and the topcoat paint will mix together, and the color of the topcoat paint will not come out.

[0053] In addition, when wood that has been coated with an impregnating paint is coated with the paint, the paint penetrates into the interior from the surface, and when the surface preparation method shown in FIG. 5 is applied to produce surface-prepared wood 2, impregnating paint residues (corresponding to paint residues) may remain in the first layer (corresponding to base layer 3) and / or the second layer (corresponding to resin-mixed layer 5) on the surface side of the first layer. Even if paint residues remain in the first layer and / or second layer, urethane bond reinforcement can be formed in the second layer (corresponding to resin-mixed layer 5) on the surface side of the first layer, so there is no problem. Even if paint residues remain in the first layer and / or second layer, the color of the pigment remains on the surface, so there is no problem in bringing out the color of the topcoat paint when repainting later. Also, the impregnating paint was originally applied to the painted wood to make the grain of the wood visible, and the base colorant applied before the application of the surface conditioner can play the role of a grain enhancer, making the grain of the painted wood stand out. In particular, it is a novel idea to apply a base colorant to wood that has been coated with an impregnating paint and has deteriorated over time to make the grain of the wood stand out. In the surface-conditioned wood 2, the resin mixed layer 5 and the colorant layer 8 soaked in the surface conditioner are mixed and adhered together by urethane bonds, so that the resin mixed layer 5 and the colorant layer 8 do not separate. The presence of the base layer 3, the resin mixed layer 5, and the colorant layer 8 in the surface-conditioned wood 2 in this state can be confirmed by, for example, infrared spectroscopy. When a film-forming or semi-film-forming paint is applied to the surface of the surface-prepared wood 2 in this state as a repainting paint, the paint film (paint fixation product) formed by the repainting will adhere appropriately to the surface-prepared wood 2, just as in the case of applying a repainting paint to the surface-prepared wood 1 (see FIG. 2). Although not shown, the repainted wood produced by repainting the surface-prepared wood 2 also has a new paint film 17 (see FIG. 4) formed by repainting, similar to that present in the repainted wood 10 (see FIG. 4). On the other hand, when an impregnation-type paint is applied to the surface-prepared wood 2 as a repainting paint, the application of a surface colorant makes it possible to maintain the prominent wood grain.2 and 6 show an example in which the base material layer 3 and the resin-mixed layer 5 are in contact with each other, but a layer having a lower lignin content than the base material layer 3 but no resin (a layer in which the resin is not distributed) may be present between the base material layer 3 and the resin-mixed layer 5. This layer having a lower lignin content than the base material layer 3 but no resin typically has a higher lignin content than the resin-mixed layer 5.

[0054] As described above, according to the surface conditioning method of the second embodiment, a colorant layer is formed on the surface of wood to which an impregnation-type paint has been applied, so that when a paint of the same color as the original or a different color (especially a light color) is applied later as a topcoat paint for repainting, it is possible to prevent the surface from darkening, and the color of the topcoat paint for repainting can be brought out. In addition, since the surface conditioning agent penetrates into the colorant layer and reaches the deteriorated layer of the wood, the surface conditioning agent can be applied to the wood while forming the colorant layer to condition the surface of the wood. In addition, since the two-component urethane of the surface conditioning agent that reaches the deteriorated layer of the wood hardens in the deteriorated layer, the deteriorated layer of the wood can be reinforced. In addition, according to the surface-conditioned wood of the present embodiment, a resin mixed layer and a colorant layer are formed, so that when repainting is performed later, the color of the surface colorant can be prevented from transferring to the topcoat paint for repainting. In addition, the application of the surface colorant can highlight the grain of the wood, and the application of the surface conditioning agent can reinforce the deteriorated layer of the wood, improving the weather resistance and design of the wood. In addition, since the deteriorated layer and colorant layer of the wood are reinforced by the urethane resin, the deteriorated layer that can absorb the topcoat paint for repainting can be eliminated or reduced, and wood suitable for repainting can be obtained. In addition, according to the repainted wood of this embodiment, since the above-mentioned base-prepared wood is repainted, it is possible to easily obtain wood in which the weather resistance and abrasion resistance are reproduced or improved by repainting while making it possible to bring out the color of the topcoat paint for repainting.

[0055] In the above description of the surface conditioning method according to the second embodiment, the surface conditioning agent is applied after the surface colorant is applied and dried. However, the surface conditioning agent may be mixed with the surface colorant (e.g., pigment). In this case, in the flow chart shown in FIG. 5, the surface colorant may be mixed in the step (S11) of mixing the two-liquid urethane. Furthermore, in FIG. 5, the step (S12) of applying the surface colorant and the step (S13) of determining whether a predetermined time has elapsed may be omitted, and the process may proceed to the step (S14) of applying the surface conditioning agent after the step (S11). In addition, when the surface conditioning agent is mixed with the surface colorant, the ratio of the surface colorant is preferably 50% by weight or less (weight of the surface colorant / weight of the entire surface conditioning agent), and more preferably 30% by weight or less. Even when the surface conditioning agent is mixed with the surface colorant (e.g., pigment), the grain of the wood can be accentuated, and the weather resistance and design of the wood can be improved. Furthermore, although the wood to which the surface preparation method shown in Fig. 5 is applied has been described as wood that has been coated with an impregnation-type paint, it may also be applied to wood that has been coated with a film-forming or semi-film-forming paint. When the surface preparation method shown in Fig. 5 is applied to wood that has been coated with a film-forming or semi-film-forming paint, the surface-prepared wood will have a colorant layer (base colorant) on the surface of the old paint film (paint residue). Even in this case, the fact remains that the base colorant is provided on the surface side of the resin-mixed layer (second layer).

[0056] In the above explanation, the surface preparation method shown in Figs. 1 and 5 is applied to wooden parts of a building that are exposed to the outdoors. However, it may also be applied to other materials besides buildings, such as furniture that is placed outdoors or placed indoors next to a window that receives sunlight, wind, and rain.

[0057] In the above explanation, when the surface conditioner contains a diluent, an organic solvent is used as the diluent (i.e., a solvent-based surface conditioner is used), but water may be used as the diluent (this is called an "aqueous surface conditioner"). However, the present inventors have found that solvent-based surface conditioners have better penetration into old paint films than aqueous surface conditioners, so it is preferable to use a solvent-based surface conditioner for wood that has been coated with a film-forming or semi-film-forming paint.

[0058] In the above description, wood that has not been heat-treated (hereinafter referred to as "untreated wood") is assumed as the base wood for the painted wood (wood having paint residue), but heat-treated wood may also be used. Heat-treated wood is typically wood produced by heat treatment at 150°C to 240°C under a nitrogen atmosphere or a water vapor atmosphere. Heat-treated wood can be produced only by heat treatment without using chemicals. Heat-treated wood usually has improved decay resistance and dimensional stability compared to untreated wood. In addition, heat-treated wood becomes hydrophobic by heat treatment, and the water repellency of the wood surface increases. On the other hand, it has been reported that when heat-treated wood is painted, the coating peels off more frequently than untreated wood, and it is also easily eroded by the effects of sunlight, rain, wind, etc. Heat-treated wood generally has a higher acidity than untreated wood because acetic acid and formic acid are generated by heat treatment, and has a lower density than untreated wood. For this reason, heat-treated wood is susceptible to erosion outdoors, and there is a risk that normal wood protection paints will not provide sufficient weather resistance. However, even if heat-treated wood has poor weather resistance and deteriorates quickly compared to untreated wood, the deteriorated layer of the heat-treated wood can be reinforced with urethane resin by applying the above-mentioned surface preparation method, and surface-prepared wood that has the advantages of heat-treated wood and has suppressed deterioration can be obtained. EXAMPLES

[0059] Hereinafter, an embodiment of the above-mentioned surface preparation method will be described. In the embodiment described below, three types of test wood were prepared. As the first test wood, a piece of wood was prepared in which a semi-film-forming paint, Semiopaque (registered trademark), manufactured by Mitsui Chemical Industrial Products, Inc., was applied to the surface of the wood, which was processed into a flat plate shape, and the wood was exposed to sunlight, wind, and rain for about seven years outdoors. The wood shown in FIG. 3 is this first test wood. As can be seen from FIG. 3, in the first test wood, a cotton-like deteriorated layer 9 of wood is observed between the base layer 3 and the old paint film 7. On the other hand, as the second test wood, a piece of wood was prepared in which a film-forming paint, Nonrot Bruno (registered trademark), manufactured by Mitsui Chemical Industrial Products, Inc., was applied to the surface of the wood, which was processed into a flat plate shape, and an accelerated weather resistance test equivalent to about 12 years was performed. The accelerated weather resistance test was performed using a xenon lamp method specified in JIS K5600-7-7. Finally, the third test wood was prepared by coating the surface of redwood processed into a flat board with Xyladecor (registered trademark) made by Osaka Gas Chemicals Co., Ltd., an impregnation type paint, and carrying out the above-mentioned accelerated weather resistance test for approximately five years. The first test wood, second test wood, and third test wood were then subjected to surface preparation under the following conditions.

[0060] The wood that had been subjected to the surface preparation was further subjected to an adhesion test as shown in FIG. 7. In this adhesion test, a cellophane adhesive tape 99 was applied to the surface of the surface-prepared wood 1, which corresponds to the first test wood and the second test wood that had been subjected to the surface preparation. The cellophane adhesive tape 99 was then peeled diagonally upward at an angle θ of 60 degrees between one end of the tape and the part attached to the surface-prepared wood 1. If the old coating film 7 did not peel off, the wood was judged to have passed the test. The same adhesion test was also performed on the surface-prepared wood 2 (see FIG. 6), which corresponds to the third test wood that had been subjected to the surface preparation, and if the coloring agent layer 8 did not peel off, the wood was judged to have passed the test. This adhesion test was in accordance with JIS K5600-5-6, but differed from the above standard in that no incisions were made on the surfaces of the surface-prepared wood 1 and 2. The reason why no cuts were made in the adhesion tests here is that wood that has aged outdoors often has cracks, and making cuts would be likely to chip the wood.

[0061] Example 1 <Test wood used> First test wood <Two-component urethane> Base material: Capital Paints Co., Ltd.'s "CX-520 Urethane Sealer A Liquid" Hardener: Capital Paints "CX-520 Urethane Sealer Liquid B" <Diluent> "NA Urethane Thinner" manufactured by Capital Paints Co., Ltd. <Preparing the surface conditioner> 100 parts by weight of the base material of the above two-component urethane and 50 parts by weight of the hardener were mixed together to obtain 150 parts by weight of two-component urethane paint. The weight ratio of the base material to the hardener at this time was 2.0 (=100 / 50). 150 parts by weight of this two-component urethane paint was mixed with 100 parts by weight of a diluent to obtain a surface conditioner. The weight ratio of the diluent to the two-component urethane at this time was 0.67 (=100 / 150).

[0062] <Application of surface conditioner> The surface of the first test wood was wiped with a rag to lightly remove dust, and then the above-mentioned surface conditioner was applied over the remaining old coating film. The surface conditioner was applied to the surface of the first test wood and left for about 2 minutes, and then the surface was wiped with a rag to remove excess surface conditioner. The wood was then left for another 2 hours to obtain a surface-conditioned wood. A micrograph of the surface-conditioned wood obtained in this manner is shown in FIG. 8. As can be seen from FIG. 8, the part that was a deteriorated layer before the surface conditioner was applied has lost its cotton-like appearance and has become a resin mixed layer 5 reinforced with urethane resin. The tactile sensation of the part reinforced with urethane resin was hardened, and no signs of separation along with the old coating film 7 were observed. When the above-mentioned adhesion test was performed on the obtained surface-conditioned wood, no old coating film was attached to the cellophane adhesive tape. In other words, it was confirmed that the surface-conditioned wood obtained by the surface conditioning method of Example 1 did not have peeling of the old coating film and passed the adhesion test. The resulting wood was then coated with Semi-Opaque (registered trademark), a semi-film-forming paint, and checked five days later to confirm the presence of a healthy coating. The repainted wood thus obtained was also subjected to the above-mentioned adhesion test, and it was confirmed that the new coating had not adhered to the cellophane adhesive tape, in other words, that the new coating had not peeled off, and that the adhesion test had been passed.

[0063] Example 2 Example 2 was carried out under the same conditions as Example 1, except that the second test wood was used as the test wood. That is, in Example 2, the same two-liquid urethane and diluent used in Example 1 were mixed in the same ratio as in Example 1 to obtain the same surface conditioner as in Example 1. This surface conditioner was applied to the second test wood in the same manner as in Example 1 to obtain surface-conditioned wood. When the surface-conditioned wood obtained in this way was examined, the part that was a deteriorated layer before the surface conditioner was applied was reinforced with urethane resin. The tactile sensation of the part reinforced with urethane resin was hardened, and no sign of separation along with the old coating was observed. When the above-mentioned adhesion test was performed on the surface-conditioned wood obtained, the old coating was not attached to the cellophane adhesive tape. That is, it was confirmed that the surface-conditioned wood according to Example 2 did not have peeling of the old coating and passed the adhesion test. Thereafter, the obtained surface-conditioned wood was coated with Semi-Opaque (registered trademark), a semi-film-forming paint, in the same manner as in Example 1, and after 5 days, it was confirmed that a healthy coating film was present. The repainted wood thus obtained was also subjected to the above-mentioned adhesion test, and it was confirmed that the new coating film did not adhere to the cellophane adhesive tape, in other words, the new coating film did not peel off, and the adhesion test was passed. In Example 2, a semi-film-forming paint different from the film-forming paint that formed the old coating film was used as the repainting paint, but it is presumed that the same results would be obtained if the film-forming paint that formed the old coating film was used.

[0064] Example 3 <Test wood used> First test wood <Two-component urethane> Main ingredient: "Polyurex Eco No. 250 Wood Sealer P Liquid" manufactured by Washin Chemical Industry Co., Ltd. Hardener: "Polyurex Eco No. 250 Wood Sealer D Liquid" manufactured by Washin Chemical Industry Co., Ltd. <Diluent> "NA Urethane Thinner" manufactured by Capital Paints Co., Ltd. <Preparing the surface conditioner> 100 parts by weight of the main agent of the above two-component urethane was mixed with 100 parts by weight of the hardener to obtain 200 parts by weight of two-component urethane paint. The weight ratio of the main agent to the hardener at this time was 1.0 (=100 / 100). 50 parts by weight of the diluent was mixed with 200 parts by weight of this two-component urethane paint to obtain a surface conditioner. The weight ratio of the diluent to the two-component urethane at this time was 0.25 (=50 / 200).

[0065] <Application of surface conditioner> The surface of the first test wood was wiped with a rag to lightly remove dust, and then the above-mentioned surface conditioner was applied over the remaining old coating film. The surface conditioner was applied to the surface of the first test wood and left for about 2 minutes, and then the surface was wiped with a rag to remove excess surface conditioner. The surface was then left for another 2 hours to obtain a surface-conditioned wood. When the surface-conditioned wood obtained in this manner was examined, the part that was a deteriorated layer before the surface conditioner was applied was reinforced with urethane resin. The tactile sensation of the part reinforced with urethane resin was hardened, and no signs of separation along with the old coating were observed. When the above-mentioned adhesion test was performed on the obtained surface-conditioned wood, no adhesion of the old coating film was observed on the cellophane adhesive tape. In other words, it was confirmed that the surface-conditioned wood obtained by the surface conditioning method according to Example 3 did not have peeling of the old coating film and passed the adhesion test. The resulting wood was then coated with Semi-Opaque (registered trademark), a semi-film-forming paint, and checked five days later to confirm the presence of a healthy coating. The repainted wood thus obtained was also subjected to the above-mentioned adhesion test, and it was confirmed that the new coating had not adhered to the cellophane adhesive tape, in other words, that the new coating had not peeled off, and that the adhesion test had been passed.

[0066] Example 4 Example 4 was carried out under the same conditions as Example 3, except that the second test wood was used as the test wood. That is, in Example 4, the same two-liquid urethane and diluent used in Example 3 were mixed in the same ratio as in Example 3 to obtain the same surface conditioner as in Example 3. This surface conditioner was applied to the second test wood in the same manner as in Example 3 to obtain surface-conditioned wood. When the surface-conditioned wood obtained in this way was examined, the part that was a deteriorated layer before the surface conditioner was applied was reinforced with urethane resin. The touch of the part reinforced with urethane resin was hardened, and no sign of separation with the old coating was observed. When the above-mentioned adhesion test was performed on the obtained surface-conditioned wood, the old coating was not attached to the cellophane adhesive tape. In other words, it was confirmed that the surface-conditioned wood of Example 4 did not have peeling of the old coating and passed the adhesion test. Thereafter, the obtained surface-conditioned wood was coated with Semi-Opaque (registered trademark), a semi-film-forming paint, in the same manner as in Example 3, and after 5 days, it was confirmed that a healthy coating film was present. The repainted wood thus obtained was also subjected to the above-mentioned adhesion test, and it was confirmed that the new coating film did not adhere to the cellophane adhesive tape, in other words, the new coating film did not peel off, and the adhesion test was passed. In Example 4, a semi-film-forming paint different from the film-forming paint that formed the old coating film was used as the repainting paint, but it is presumed that the same results would be obtained if the film-forming paint that formed the old coating film was used.

[0067] Example 5 <Test wood used> Third test wood <Two-component urethane> Base material: Capital Paints Co., Ltd.'s "CX-520 Urethane Sealer A Liquid" Hardener: Capital Paints "CX-520 Urethane Sealer Liquid B" <Base coloring agent> "Pure PG Stain" by Capital Paint Co., Ltd. <Dispersant> "Pure Thinner" manufactured by Capital Paint Co., Ltd. <Preparing the base colorant> 100 parts by weight of the base colorant was mixed with 100 parts by weight of a dispersant to obtain a colorant for coating. <Preparing the surface conditioner> 100 parts by weight of the base material of the above two-component urethane and 50 parts by weight of the hardener were mixed together to obtain 150 parts by weight of two-component urethane paint. The weight ratio of the base material to the hardener at this time was 2.0 (=100 / 50). This 150 parts by weight of two-component urethane paint was used as a surface conditioner.

[0068] <Application of base coloring agents and base conditioners> The surface of the third test wood was wiped with a cloth to lightly remove dust, and then the above-mentioned coating colorant was applied. The coating colorant was applied to the surface of the third test wood and left for about 12 hours, and then the above-mentioned surface conditioner was applied on top of the colorant layer. The surface conditioner was applied to the surface of the third test wood on which the colorant layer was formed and left for about 2 minutes, and then the surface was wiped with a cloth just to be sure to remove any excess surface conditioner that may have been present. The surface was then left for another 2 hours to obtain a surface-conditioned wood. When the surface-conditioned wood obtained in this way was examined, the part that was a deteriorated layer before the surface conditioner was applied was reinforced with urethane resin and had hardened together with the surface colorant layer. The part reinforced with urethane resin felt hardened to the touch, and no signs of separation with the colorant layer were observed. The above-mentioned adhesion test was performed on the obtained surface-conditioned wood, and the colorant layer was not attached to the cellophane adhesive tape. That is, it was confirmed that the surface-conditioned wood obtained by the surface conditioning method according to Example 5 passed the adhesion test without peeling of the colorant layer. After that, the above-mentioned impregnation-type paint Xyladecor (registered trademark) was applied to the obtained surface-conditioned wood as a topcoat paint for repainting, and when checked after 5 days, the color of the topcoat paint for repainting could be confirmed. When the above-mentioned adhesion test was also performed on the repainted wood obtained in this way, it was confirmed that the new paint did not adhere to the cellophane adhesive tape, in other words, the new paint did not peel off, and the adhesion test was passed.

[0069] Example 6 <Two-component urethane> Main ingredient: "Polyurex Eco No. 250 Wood Sealer P Liquid" manufactured by Washin Chemical Industry Co., Ltd. Hardener: "Polyurex Eco No. 250 Wood Sealer D Liquid" manufactured by Washin Chemical Industry Co., Ltd. <Preparing the surface conditioner> 100 parts by weight of the base material of the above two-component urethane was mixed with 100 parts by weight of the hardener to obtain 200 parts by weight of two-component urethane paint. The weight ratio of the base material to the hardener at this time was 1.0 (=100 / 100). This 200 parts by weight of two-component urethane paint was used as a surface conditioner.

[0070] Example 6 was carried out under the same conditions as Example 5, except that the above-mentioned surface conditioner was used. That is, in Example 6, the same coating colorant used in Example 5 was applied to the third test wood, and after leaving it for about 12 hours, the surface conditioner was applied in the same manner as in Example 5 to obtain a surface-conditioned wood. When the surface-conditioned wood obtained in this way was examined, the part that was a deteriorated layer before the surface conditioner was applied was reinforced with urethane resin and hardened together with the surface colorant layer. The tactile sensation of the part reinforced with urethane resin was hardened, and no sign of separation with the colorant layer was observed. When the above-mentioned adhesion test was performed on the obtained surface-conditioned wood, the colorant layer was not attached to the cellophane adhesive tape. That is, it was confirmed that the surface-conditioned wood of Example 6 did not have the colorant layer peeled off and passed the adhesion test. Thereafter, the obtained surface-prepared wood was coated with Xyladecor (registered trademark), an impregnating paint, as a topcoat paint for repainting, in the same manner as in Example 5. When checked after 5 days, the color of the topcoat paint for repainting could be confirmed. The repainted wood thus obtained was also subjected to the above-mentioned adhesion test, and it was confirmed that the new paint did not adhere to the cellophane adhesive tape, in other words, the new paint did not peel off, and the adhesion test was passed.

[0071] Comparative Example 1 As Comparative Example 1, the above-mentioned adhesion test was carried out on the first test wood without surface preparation. When the cellophane adhesive tape was applied to the first test wood and then peeled off, the deteriorated layer and old coating film were found to be attached to the cellophane adhesive tape, and peeling of the deteriorated layer and old coating film from the first test wood was confirmed. Furthermore, Semiopaque (registered trademark), a semi-film-forming paint, was applied to the first test wood without surface preparation, and the above-mentioned adhesion test was carried out 5 days later. The deteriorated layer, old coating film, and new coating film were found to be attached to the cellophane adhesive tape, and peeling of the deteriorated layer, old coating film, and new coating film from the painted first test wood was confirmed.

[0072] Comparative Example 2 As Comparative Example 2, the above-mentioned adhesion test was carried out on the second test wood without surface preparation. When the cellophane adhesive tape was applied to the second test wood and then peeled off, the deteriorated layer and old coating film were found to be attached to the cellophane adhesive tape, and peeling of the deteriorated layer and old coating film from the second test wood was confirmed. Furthermore, Semiopaque (registered trademark), a semi-film-forming paint, was applied to the second test wood without surface preparation, and the above-mentioned adhesion test was carried out 5 days later. The deteriorated layer, old coating film, and new coating film were found to be attached to the cellophane adhesive tape, and peeling of the deteriorated layer, old coating film, and new coating film from the painted second test wood was confirmed.

[0073] Comparative Example 3 As Comparative Example 3, the above-mentioned adhesion test was carried out on the third test wood without surface preparation, which was coated with the coating colorant. When the cellophane adhesive tape was attached to the third test wood and then peeled off, the deterioration layer and colorant layer were found to be attached to the cellophane adhesive tape, and peeling of the deterioration layer and colorant layer from the third test wood was confirmed. Furthermore, the third test wood, which was coated with the coating colorant but not subjected to surface preparation, was coated with Xyladecor (registered trademark), an impregnation type paint, and when checked after 5 days, it was found to be a different color from the original color of the top coat paint for repainting. Furthermore, when the above-mentioned adhesion test was carried out, the deterioration layer, colorant layer, and new paint were found to be attached to the cellophane adhesive tape, and peeling of the deterioration layer, colorant layer, and new paint from the painted third test wood was confirmed.

[0074] From the results of each of the examples and comparative examples shown above, it was confirmed that when new paint is applied to painted wood without applying a surface conditioner containing two-component urethane, the new paint film (new paint) peels off along with the deteriorated layer, but when the surface conditioner is applied before applying new paint, peeling of the new paint film (new paint) can be prevented. [Explanation of symbols]

[0075] 1, 2 Surface-treated wood 3 Base layer (first layer) 5 Resin mixed layer (second layer) 7 Old paint film (paint residue) 8 Colorant Layer 9 Deterioration layer 10 Repainted Wood 17 New coating film (paint fixation material)

Claims

1. A step of preparing a surface conditioner containing a two-liquid urethane; and applying the prepared surface conditioner onto a painted wood having a layer in which lignin has been decomposed by ultraviolet light. Method of preparing the base material.

2. The painted wood is wood on which a film-forming or semi-film-forming paint has been applied to the surface at least once to form a coating film. The method for preparing a base material according to claim 1.

3. The surface conditioner contains an organic solvent. The method for preparing a base material according to claim 1.

4. The two-component urethane contains a base agent and a hardener, and the weight ratio of the base agent to the hardener is 0.8 or more and 3.0 or less. The method for preparing a base material according to claim 1.

5. The surface conditioner contains a diluent, and the weight ratio of the diluent to the two-component urethane is 0.1 or more and 2.0 or less. The method for preparing a base material according to claim 1.

6. applying a surface stain onto the painted wood prior to applying the surface conditioner onto the painted wood. The method for preparing a base material according to claim 1.

7. The base material conditioner includes a base material colorant. The method for preparing a base material according to claim 1.

8. A painted wood material is coated with a surface conditioner containing a two-component urethane, and the surface conditioner is applied according to the surface conditioner preparation method of any one of claims 1 to 7. Wood with pre-treated base.

9. A first layer; and a second layer located closer to the surface than the first layer; The second layer has a lower content of lignin constituting wood than the first layer and contains resin; The surface-conditioned wood material according to claim 8.

10. Wood that has been subjected to surface preparation, A first layer; and a second layer located closer to the surface than the first layer; The second layer has a lower content of lignin constituting wood than the first layer and contains resin; Wood with pre-treated base.

11. At least the surface of the second layer is provided with a paint residue remaining after a film-forming or impregnating paint, including a semi-film-forming paint, is applied and a volatile component is evaporated from the paint. The surface-conditioned wood material according to claim 9.

12. providing paint residue on at least a surface of the second layer; The surface-conditioned wood material according to claim 10.

13. A base coloring agent is provided on at least the surface side of the second layer, into which the base conditioner is soaked. The surface-conditioned wood material according to claim 9.

14. A base colorant is provided on at least the surface side of the second layer. The surface-conditioned wood material according to claim 10.

15. The surface-conditioned wood material according to claim 8, and a paint fixative present on the surface of the surface-conditioned wood that has been subjected to surface conditioning. Repainted wood.

16. The surface-conditioned wood material according to claim 10, claim 12 or claim 14, and a paint fixative that is present on the surface of the surface-conditioned wood that has been subjected to the surface conditioning and is a component of paint that has been fixed after a new coating has been applied to the surface-conditioned wood. Repainted wood.

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