Painting resin composition containing wood powder, its manufacturing method, and wood-like painted member coated with the painting resin composition

Abstract

To provide a woody coating member which has woody appearance and such characteristics that feeling and touch feeling are approximate to feeling and touch feeling of natural wood, with respect to a wood waste material, a synthetic resin or a metal base material part.SOLUTION: A synthetic resin composition 10 for film formation is composed of at least a synthetic resin component 11, a wood flour component 14 and a cellulose nanofiber (CNF) component 15, in which the wood flour component 14 is uniformly dispersed in the synthetic resin composition 10, and the cellulose nanofiber component 15 functions as a dispersion material of dispersing the wood flour component 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coating resin composition containing wood powder, a manufacturing method thereof, and a wood-like painted member coated with the coating resin composition. More specifically, the present invention relates to a coating resin composition in which wood powder and a cellulose nanofiber (CNF) component are mixed in a synthetic resin component, and the present invention relates to a wood-like painted material in which the wood powder is dispersed and arranged in a substantially uniform manner in the synthetic resin component, and to a wood-like painted member coated with the wood-like painted material. [Background technology]

[0002] Wood has traditionally been frequently used as a building and furniture material, and the associated consumption of wood has been considerable. However, in recent years, problems such as global warming, air pollution, and the occurrence of natural disasters have come to the fore. As a result, there has been an increased need to strengthen forest protection and prohibit the large-scale felling of wood, and the production of wood as a raw material for building and furniture has tended to decrease. As a result, demand has exceeded production, and adverse effects such as a rise in wood prices have begun to occur. In consideration of the above situation, as a means of meeting the demand for wood in anticipation of a decrease in production, we will recycle and reuse used or scrap wood. reclaimed wood There is a demand for the production and utilization of wood-based materials and the production of artificial wood using non-wood materials.

[0003] Methods for recycling such waste wood include, for example, a method of applying a paint that gives the surface of the waste wood or the surface of a metal substrate the appearance and feel of natural wood, as shown in JP 59-19236 A (Patent Document 1), JP 2000-343030 A (Patent Document 2), or JP 2009-209237 A (Patent Document 3), and a method of manufacturing synthetic resin wood having the appearance, texture, and feel of wood by mixing a cellulosic fiber component into an appropriate synthetic resin component and molding it into a wood-like shape, as shown in JP 2015-137340 A (Patent Document 4). Furthermore, a method is known in which the surface of a synthetic resin body or a metal material is embossed using an appropriate device to reveal a wood grain pattern, as shown in JP 2008-120019 A (Patent Document 5) and Japanese Patent No. 3030009 (Patent Document 6).

[0004] However, the techniques for producing artificial wood based on synthetic resins containing fibrous components, and the method of embossing the outer surface of synthetic resin or metal materials to form wood grain patterns, all result in high production costs, and it has been difficult to cheaply and easily produce artificial wood that has properties similar to the appearance, texture and feel of natural wood. Furthermore, even if wood powder (shavings) is mixed into the molten synthetic resin component that forms the base of the paint, the wood powder will bond strongly to each other and form large lumps, making it unsuitable for painting and making it impossible to give non-wood substrates the same feel, appearance and texture as natural wood. In particular, nozzle clogging can be a major problem when spray painting.

[0005] For this reason, the inventors of the present application intend to actively contribute to environmental conservation and the prevention of global warming by using an improved paint to recycle the natural wood and actively utilize the artificial natural wood. Specifically, when wood flour or sawdust is mixed into the synthetic resin component, which is the main component of the paint and is liquefied with water or an organic solvent, the wood flour or sawdust is prevented from agglomerating together in the synthetic resin component to form large lumps, and the wood flour or sawdust is controlled so that it is individually and independently uniformly dispersed in the synthetic resin component, and the new paint is applied to the surface of waste wood, metal material, or synthetic resin material. It allows for easy and efficient application regardless of the coating method. . [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 59-19236 [Patent Document 2] JP 2000-343030 A [Patent Document 3] JP 2009-209237 A [Patent Document 4] JP 2015-137340 A [Patent Document 5] JP 2008-120019 A [Patent Document 6] Patent No. 3030009 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0007] Therefore, the main object of the present invention is to easily and inexpensively provide a synthetic resin composition, for example a paint, in which fine wood powder or sawdust is individually and independently dispersed and blended uniformly in a desired synthetic resin composition without agglomerating with each other, and further to provide a method for producing said synthetic resin composition, and a wood-like painted member formed by applying said synthetic resin composition, for example a paint, which has a wood-like appearance and a texture and feel that are similar to the texture and feel of natural wood. [Means for solving the problem]

[0008] In order to achieve the above object, the synthetic resin composition for forming a coating according to the first aspect of the present invention employs the following basic technical configuration. In other words, the basic technical configuration of the synthetic resin composition for forming a coating according to the present invention is a synthetic resin composition for forming a coating, including for use in painting, which is composed of at least a synthetic resin component, a wood flour component, and a cellulose nanofiber (CNF) component, and is characterized in that the wood flour component is uniformly dispersed and present within the synthetic resin composition. The synthetic resin composition in the first aspect of the present invention is primarily used for painting, but can also be used for purposes other than painting, as described below. Effect of the Invention

[0009] The synthetic resin composition for forming a coating according to the present invention, as a result of adopting the basic technical configuration as described above, is a synthetic resin composition for forming a coating in which fine wood powder or sawdust does not aggregate with each other and is individually and independently uniformly dispersed and blended in the desired synthetic resin composition, compared to conventional coating materials of the same type. For example, when used for painting, it is possible to provide painting work easily and at low cost. Furthermore, compared to conventional paints that give the texture, appearance and feel of wood materials known in the art, a coating material is obtained that can form a coating that is full of luxury and can further reveal the appearance, texture and feel of natural wood. Therefore, not only can waste wood be recycled, but artificial wood can also be easily produced by applying a coating to the surface of a metal or synthetic resin substrate. This makes it possible to provide a coating that reduces the consumption of natural wood, contributes to the promotion and preservation of forest systems and the prevention of natural disasters, and can also greatly contribute to the prevention of air pollution and global warming. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating the outline of the structure of the synthetic resin composition for forming a coating film used in the present invention. [Diagram 2] FIG. 2 is a perspective view illustrating an outline of a wood-like painted member obtained according to the present invention. [Diagram 3] FIG. 3 is a cross-sectional view illustrating an outline of a specific configuration of a wood-like painted member obtained according to the present invention. [Figure 4] FIG. 4 is a cross-sectional view illustrating the outline of the structure of another embodiment of the wood-like painted member obtained by the present invention. [Diagram 5] FIG. 5 is a diagram illustrating the outline of the configuration of one specific example of a coating device for forming a wood grain pattern or a knot pattern on the surface of a base part or on the surface of a coating layer formed on the surface of a base part in a coating process in the present invention. [Figure 6] FIG. 6 is a diagram illustrating the outline of the configuration of one specific example of a coating device for manually forming a wood grain pattern or a knot pattern on the surface of a base part or on the surface of a coating layer formed on the surface of a base part in a coating process in the present invention. [Figure 7] FIG. 7 is a diagram illustrating the outline of the configuration of another specific example of a coating device for forming a wood grain pattern or a knot pattern on the surface of a base part or on the surface of a coating layer formed on the surface of a base part in a coating process in the present invention. [Figure 8] FIG. 8 is an electron microscope photograph of the synthetic resin composition for coating used in the present invention. [Figure 9] FIG. 9 is a reference diagram for explaining the electron microscope photograph of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Specific examples of the synthetic resin composition for forming a coating according to the present invention will be described in detail below with reference to the drawings. That is, as shown in FIG. 1, the basic technical configuration of the synthetic resin composition 10 for forming a coating, which is the first aspect of the invention, is a synthetic resin composition 10 having a configuration in which a synthetic resin component 11, a wood flour component 14, and a cellulose nanofiber (CNF) component 15 are mixed in at least an appropriate solvent component 13, and the synthetic resin composition 10 for forming a coating is characterized in that the wood flour component 14 is uniformly dispersed and arranged within the synthetic resin composition 10. Needless to say, the synthetic resin composition 10 for forming a coating according to the present invention may further contain a pigment 12 and, although not shown, appropriate hardeners, additives, and the like, if necessary.

[0012] When the synthetic resin composition 10 for forming a coating in the present invention is used for painting, the mating substrate 1 on which the coating material 10 is used is not particularly limited, and it may be applied to the surface of wood, particularly waste wood, or it may be applied to the surface of a member made of a synthetic resin material or a metal material.

[0013] As already pointed out above, cellulose fiber or wood powder such as sawdust is mixed into a general paint, and then the paint is dried or baked appropriately after application to volatilize or evaporate the solvent, resulting in a paint as shown in FIG. 50 wood grain patterns It is already known that by forming a solid layer coating 6 that is developed, the surface appearance, feel or texture of the substrate 1 can be appropriately changed to a wood-like appearance, feel or texture and used as recycled wood, but in this prior art, when wood powder or cellulose fibers are mixed into the paint 10, the wood powder or cellulose fibers often gather and coagulate with each other to form large clumps, and therefore even if a paint in this state is used, the surface of the completed coated body still has many large clumps of wood powder or cellulose fibers remaining, which is completely dissimilar to the surface appearance, feel or texture of natural wood, and therefore has no commercial value. Therefore, there are no examples of the above technology being put into practical use.

[0014] In addition, in the above-mentioned conventional technology, the wood powder lumps would adhere to and remain on the nozzle when painting, clogging the spray nozzle in spray painting using an air flow, making it impossible to use spray painting and resulting in the problem that efficient painting was not possible. If we look at the basic and general composition of paint for painting, it is made up of pigments, resin components for forming a film, hardeners, additives, and a solvent for dissolving the resin components. Paints whose solvent is water are called water-based paints, and those whose solvent is an organic solvent such as thinner are called oil-based paints. However, if one attempts to later mix wood powder or shavings into such paint, the wood powder or shavings will aggregate and clump together in the molten synthetic resin to form large lumps, resulting in the problems described above.

[0015] In response to this, the inventors of the present application have conducted intensive research and conducted numerous experiments, and as a result, have found that by mixing an appropriate amount of cellulose nanofiber (CNF) component 15 when mixing the wood flour or plank shavings 14, etc. into the synthetic resin component 11 of the paint component, as shown in Figure 1, it is possible to prevent the wood flour or plank shavings, etc. 14 from gathering together and agglomerating into large lumps in the synthetic resin composition 10, and the wood flour or plank shavings, etc. are uniformly dispersed and present in the synthetic resin composition. That is, in the present invention, the cellulose nanofiber (CNF) component 15 functions as a dispersant for dispersing the wood flour or sawdust or other component 14 uniformly and independently within the synthetic resin composition.

[0016] Moreover, the synthetic resin composition 10 for forming a coating film as the coating material according to the present invention has the characteristics of being completely recyclable and also capable of achieving a CO2 reduction effect. The cellulose nanofiber (CNF) component 15 used in the present invention is a fibrous material obtained by finely breaking down and decomposing the cellulose fibers that make up wood to the nano level, and has a fineness, i.e., average diameter, of 1 nm to 100 nm, preferably 3 nm to 4 nm, a fiber length of several hundred nm to 1 μm, and an aspect ratio of 100 or more.

[0017] The cellulose nanofiber (CNF) component 15 used in the present invention exists in a wet state in which it is dissolved in water, and in a dry state in which it is maintained in a powder form, and either state can be used in the present invention. However, the cellulose nanofiber (CNF) component 15 in a wet state is only applicable when using a paint raw material that uses water as the solvent, while the cellulose nanofiber (CNF) component 15 in a dry state is preferably used when using an organic solvent as the solvent. The resin component 11 used in the synthetic resin for forming a coating 10 according to the present invention is not particularly limited, but preferably used are olefin-based resins, acrylic-based resins, urethane-based resins, fluorine-based resins, epoxy-based resins, melamine-based resins, etc.

[0018] Furthermore, the wood flour or sawdust 14 used in the present invention is not particularly limited in terms of the type or quality of wood, and almost any wood material can be used. It is particularly desirable to use sawdust or wood flour obtained from wood such as cypress, cedar, and camphor. The grain size of the wood flour or sawdust 14 used in the present invention is not particularly limited, but for example, grain sizes of 20 μm to 200 μm can be used, and preferably around 50 μm.

[0019] Furthermore, the pigment 12, hardener, additives, etc. in the present invention are not particularly limited, and appropriate known materials can be selected and used as necessary. On the other hand, the type of the solvent 13 used in the present invention is not particularly specified, and organic solvents generally called thinners and aqueous solvents mainly composed of water can be appropriately selected and used depending on the purpose of use of the paint and the type of application substrate. Furthermore, it is desirable to vary the mixing ratio of each of the above components in the synthetic resin composition for forming a coating 10 used in the present invention somewhat depending on the application and purpose of use, but it is generally desirable to mix 0.3 to 10 parts by weight of the wood flour component 14 and 0.5 to 10 parts by weight, preferably 0.5 to 5 parts by weight, of the cellulose nanofiber (CNF) component 15 per 100 parts by weight of the synthetic resin component 11.

[0020] In the synthetic resin composition 10 for forming a coating according to the present invention, the inventors of the present application conducted an analysis with reference to many experimental results as to the reason why the wood flour or sawdust 14, etc. are individually and independently uniformly dispersed within the synthetic resin component 10. As a result, it was found that the wood flour or sawdust, etc. 14 is stirred and mixed together with the cellulose nanofiber (CNF) component 15 within the synthetic resin composition 10 containing the synthetic resin 11, so that a plurality of the cellulose nanofiber (CNF) components 15 are arranged in the vicinity of the peripheral edges of the wood flour or sawdust, etc. 14, and it was understood that the cellulose nanofiber (CNF) component 15 effectively prevents a plurality of the wood flour, etc. 14 from approaching each other and bonding / aggregating to form large lumps within the synthetic resin composition.

[0021] That is, as shown in FIG. 1, the synthetic resin composition for painting (paint) 10 according to the present invention has a mixture of multiple synthetic resin components 11, pigment components 12, and wood flour components 14 arranged inside a solvent 13, while multiple cellulose nanofiber (CNF) components 15 are arranged in relatively large numbers around the wood flour components 14, and are arranged in a shape as if the cellulose nanofiber (CNF) components 15 were surrounding the wood flour components 14. It is understood that this structure probably effectively prevents the wood flour components 14 from bonding and adhering to each other in the synthetic resin composition 10 containing the synthetic resin components 11.

[0022] In other words, the cellulose nanofiber (CNF) component 15 prevents the wood flour components 14 from bonding and adhering to each other in the synthetic resin composition 10, and functions to disperse them uniformly. As is clear from the above explanation, the synthetic resin composition for painting 10 according to the present invention can be used as a water-based paint, and it goes without saying that it can also be used as an oil-based paint.

[0023] Furthermore, the present invention For film formationWhen the synthetic resin composition 10 is used for painting, it is possible to form a coating by applying it to the surface of ordinary wood 1 and drying it, and it is also possible to apply it to the surface of wood 1 that constitutes waste wood in order to regenerate the surface of the waste wood.Furthermore, by applying it to the surface of an appropriate member 1 made of an appropriate synthetic resin material or metal material, it is possible to obtain a pseudo-woody substrate that looks or feels like natural wood in terms of appearance, texture, and feel, even though the substrate member 1 is a non-woody material.

[0024] In the present invention, it is also possible to further include in the synthetic resin composition 10 for forming a coating a desired amount of a fragrance component 16 that emits a wood fragrance. The fragrance component 16 is not particularly limited, and it is possible to use a commercially available air freshener 16 that emits the scent of wood such as cedar, cypress, camphor, or Japanese cypress, such as cypress oil or cedar oil. By using this, a subtle wood scent is emitted from a suitable substrate, including wood, to which the synthetic resin composition for forming a coating 10 according to the present invention has been applied, providing a mood-changing and mental-soothing effect. Furthermore, the synthetic resin composition 10 for forming coatings according to the present invention can function as either an oil-based paint or a water-based paint depending on the type of solvent used, and can be used in different ways depending on the type of substrate to which it is to be applied.

[0025] On the other hand, the synthetic resin composition 10 for forming a coating according to the present invention can be applied to modify the surface of a substrate 1 made of a wood-based material, but it goes without saying that it can also be applied to the surface of a substrate 1 made of a metal material or a synthetic resin material.

[0026] Next, a basic technical configuration of the second aspect of the present invention will be described. That is, the basic technical configuration of the second aspect of the present invention is a method for producing the synthetic resin composition 10 for forming a coating in the first aspect described above, which is basically characterized by a first step of mixing a desired amount of cellulose nanofiber component (CNF) 15 into a desired synthetic resin component 11 dissolved in an appropriate solvent 13 and carrying out an appropriate stirring treatment for a desired time, and after the first step is completed, a second step of mixing a desired amount of wood flour 14 into the synthetic resin composition 10 consisting of the synthetic resin component 11 containing the cellulose nanofiber component (CNF) 15, and then a third step of stirring the synthetic resin composition 10 containing the synthetic resin component 11, the cellulose nanofiber component (CNF) 15, and the wood flour 14 for a desired time.

[0027] A specific example of the second aspect of the present invention will be described below. First, for example, an acrylic synthetic resin component 11 is dissolved in a suitable organic solvent 13 to prepare a synthetic resin emulsion, that is, a synthetic resin composition 10 which is the basic component of the present invention, and is placed in a container equipped with a suitable stirring device. Next, cellulose nanofiber (CNF) component 15 equivalent to 0.5 parts by weight per 100 parts by weight of the acrylic synthetic resin component 11 is added to the synthetic resin composition 10 in the container of the stirring device, and the synthetic resin composition 10 is stirred until the cellulose nanofiber (CNF) component 15 is sufficiently defibrated.

[0028] Then, the synthetic resin composition 10 containing the defibrated cellulose nanofiber (CNF) component 15 is mixed with an appropriate amount of a wood flour component 14 equivalent to 1.0 part by weight per 100 parts by weight of the acrylic synthetic resin component 11, and, if necessary, a pigment having an appropriate hue, color, and brightness, and an appropriate hardener or additive, and then the mixture is stirred for several minutes at room temperature using the same stirring device. By carrying out this operation, the synthetic resin composition 10 for forming a coating film according to the present invention is completed. In the process for producing the synthetic resin composition for forming a coating 10 in the second embodiment of the present invention, it is also desirable to further mix in an aromatic agent that releases an appropriate woody scent in addition to the pigment.

[0029] Furthermore, in the second aspect of the present invention, as described below, when the synthetic resin composition 10 for forming a coating is used as a paint, it is also a preferred embodiment that a plurality of types of synthetic resin compositions 10 for forming a coating are individually produced in advance by mixing pigments having different hues, colors, or brightnesses as pigments, and that in the coating operation described below, the synthetic resin compositions 10 for forming a coating, which differ from each other in hues, colors, or brightnesses, can be used separately when coating each layer in the overcoating process. For example, when a brownish hue is used as a pigment in one synthetic resin composition for forming films 10, a method is also possible in which the same brownish pigment but with a different saturation or brightness is used in another synthetic resin composition for forming films 10'. Also, different synthetic resin compositions for forming films 10, 10', 10'', etc. may be produced by using pigments with different hues themselves as pigments. In other words, in the present invention, synthetic resin compositions 10', 10" and the like for forming coatings, which have a color with a different saturation or brightness from that of the synthetic resin composition 10 for forming coatings having a basic wood-like color or brightness, are used as synthetic resin compositions for forming a wood-like pattern, as described below. Furthermore, in the present invention, the first synthetic resin composition for forming a coating 10 incorporates the full range of constituent components as described above, but the second and third synthetic resin compositions for forming a coating 10', 10" may not contain the cellulose nanofiber (CNF) component or the water-soluble cellulose component in the synthetic resin component, and in such a specific example, it is desirable that the color or hue of the pigment contained in the resin component is set to be different from the color or hue of the pigment in the first synthetic resin composition for forming a coating 10.

[0030] Next, a specific technical configuration relating to the third aspect of the present invention will be described in detail with reference to FIGS. In other words, the basic technical configuration of the third aspect of the present invention is a wood-like painted member 30 characterized in that, when the synthetic resin composition 10 for forming a coating, which has been described in detail above, is used as a paint on the outer surface 7 of a desired substrate 1, at least one coating layer 2 made of the synthetic resin composition 10 for coating is formed, and the outer surface 31 of the coating layer 2 in the painted member 30 is characterized in that it has a feel, texture, and roughness that is approximately similar to the feel, texture, and roughness of natural wood.

[0031] That is, in the third aspect of the present invention, the synthetic resin composition for coating 10 described above is applied to the outer surface 7 of a substrate 1 having an appropriate shape by using an appropriate coating means to form a coating layer 2 having a uniform thickness, and then, through an appropriate baking process or drying process, the solvent component 13 contained in the synthetic resin composition for coating 10 is volatilized or evaporated and removed, and the synthetic resin component 11 is solidified, thereby forming a coating film 2 having a desired thickness on the outer surface 7 of the substrate 1. The coating means in this embodiment is not particularly limited, and it is possible to use a general coating method or a spray coating method using a suitable sprayer.

[0032] In the specific example of this embodiment of the present invention, the thickness of the coating film layer 2 is not specified, but it is possible to adopt an appropriate thickness between 0.01 mm and 1 mm, for example. On the other hand, the material of the substrate 1 to which the synthetic resin composition for coating 10 in the third embodiment is applied is not particularly specified, and it may be a wood material or may be composed of one material selected from the group consisting of synthetic resin materials and metallic materials. It is also a preferred embodiment to form an undercoat layer on the outer surface 7 of the substrate 1 using a suitable undercoat agent before carrying out the coating operation. In the present invention, when the undercoating step as described above is carried out, the step of forming the coating film 2 using the synthetic resin composition for coating 10 described above may be referred to as an undercoating step.

[0033] The wood-like painted member 30 formed according to the third embodiment has the wood powder 14 contained in the paint uniformly dispersed on the painted surface, and therefore has a wood-like appearance and a texture and feel similar to those of natural wood. Provided It is something. Therefore, the wood-like painted member 30 obtained by the present invention has a wide range of uses, and can be used not only as exterior materials for buildings, but also as exterior-related components, interior materials or fittings for buildings, and can also be applied to furniture in general.

[0034] In the third embodiment of the present invention, in producing the wood-like painted member 30, for example, as shown in FIG. 3, when a paint composed of the synthetic resin composition for paint 10 is applied to the outer surface 7 of the desired substrate 1, the painting operation may be stopped at one time to form a single paint layer 2 on the outer surface 7 of the substrate 1. Alternatively, as another embodiment, as shown in FIG. 4, when a paint composed of the synthetic resin composition for paint 10 is applied to the outer surface 7 of the desired substrate 1, the painting operation may be repeated two or more times to form a first paint layer 2 on the outer surface 7 of the substrate 1, and a second paint layer 21 or a third paint layer 22 may be further applied in multiple layers on top of the first paint layer 2 formed on the outer surface 7 of the substrate 1.

[0035] In such a specific example, preferably, when multiple coating layers 2, 21, 22, etc. made of the synthetic resin composition for paint 10 are formed on the outer surface 7 of the desired substrate 1, the pigment contained in each coating layer is appropriately changed so that each layer is configured to differ from the others in either the overall color, tone, or density. When the above-mentioned synthetic resin composition for painting containing wood powder 10 is applied to the outer surface 7 of a suitable substrate 1 in multiple layers, it is preferable to first subject the surface of the outer surface 7 of the substrate 1 to an appropriate well-known pretreatment operation (priming step), and then apply the synthetic resin composition for painting containing wood powder 10 to form the first coating layer 2 (also referred to as the undercoat step).

[0036] Then, a paint that is the synthetic resin composition 10 for paint use containing a pigment that is the same as or different from the pigment contained in the paint that is the synthetic resin composition 10 for paint use that formed the first paint layer 2 is applied onto the first paint layer 2 to form a second coating layer 21. In the present invention, The second and third steps This is generally referred to as the topcoat treatment process. This process is utilized when forming a wood grain pattern or the like on the outer surface of the wood grain painted member 30 according to the present invention. Specifically, when an appropriate second coating layer 21 or third coating layer 22 is formed on the first coating layer 2, the synthetic resin composition for coating constituting the layer can be one that does not contain a cellulose nanofiber (CNF) component. The wood-like painted member 30 according to the present invention, which is completed through the above-mentioned painting process, has a plain appearance because the color of the outer surface 7 is a single color tone and does not have the same grain or knot patterns as those of real natural wood. deer However, there is a problem in that the resulting product has little commercial value. Therefore, in the present invention, the second coating layer 21 or Third When applying an appropriate pattern including a wood grain pattern to the paint layer 22, each layer may be formed to a uniform thickness, and then the surface may be scraped off in a comb-like manner using an appropriate brush, paint brush, or paint brush to form an appropriate pattern portion 50 consisting of bulges 4 as shown in Figures 2 to 4. Alternatively, when forming the second paint layer 21 or the third paint layer 22, it is also possible to employ a method in which an appropriate pattern is applied from the beginning as shown in Figure 5, thereby directly forming an appropriate bulged pattern 50. In this treatment process, the coating thickness in the undercoat process is generally 15 to 25 μm, the coating thickness in the intermediate coat process is generally 30 to 40 μm, and the coating thickness in the top coat process is generally 0.05 mm to 1.0 mm.

[0037] In other words, in the third aspect of the present invention, as shown in FIG. 4, a desirable example is to use the paint that is the synthetic resin composition for painting 10 to paint a pattern having a suitable uniform or non-uniform width and length, and a suitable uniform or non-uniform thickness, so as to form bulging portions 4 that bulge out from the outer surface 7 of the wood-like painted member 30, as if forming a grain pattern or knot pattern found in natural wood. In this case, it is desirable that the pigment contained in the synthetic resin composition for painting 10 that constitutes the bulge 4 has a hue that is darker than the hue of the pigment that constitutes the first, second, or third paint layer 2, 21, or 22. The thickness of the bulge 4 is not particularly limited, but may be selected from an appropriate thickness between 0.01 mm and 1.0 mm, for example.

[0038] On the other hand, in the third embodiment of the present invention, when a plurality of coating layers are formed on the outer surface 7 of the base 1, as shown in FIG. 6, the surface of the coating layer 21 or 22 forming the uppermost layer is appropriately Wood grain pattern Alternatively, a formwork or pattern frame 35 having a portion 36 cut out of a knot pattern is used to cut the surface of the coating layer 21 or 22 into the pattern, As shown in FIG. 3 or FIG. 4 Another preferred embodiment is to form recessed linear portions 5 to imitate wood grain or a knot pattern, or to paint and print the coating material according to the present invention along the cuts to create a wood grain pattern. In this specific example, the pigment of the coating layer 21 or 22 constituting the upper layer portion is greater than the pigment of the coating layer 2 or 21 constituting the lower layer portion. dark In one embodiment, a pigment having a hue is preferably used.

[0039] In the third embodiment of the present invention described above, when a pattern 50 having a suitable uniform or non-uniform width and a suitable length and a suitable uniform or non-uniform thickness is to be formed by swelling on the coating layer 2 formed on the outer surface of the suitable fuselage part 1, or on the outer surface 7', 7" of another coating layer 21 or 22 further formed on the coating layer 2 already formed on the outer surface 7 of the suitable base part 1, the coating synthetic resin composition 10 is applied to the upper surface 7 of the base part 1 along the surface of the coating layer 2 in the vicinity of the upper surface 7 of the base part 1 on which the desired coating layer 2 is formed, as shown in FIG. In the longitudinal direction (S1) The base member is provided so as to be movable in a direction perpendicular to the longitudinal axis of the base member. (S2) Alternatively, a paint supply body 37 that is movable to the outside may be used to form a bulging pattern using the paint 10.

[0040] In this specific example, the paint supply body 37 has the paint supply section 40, and at least one, and preferably a plurality of ink ejection nozzles 38 are provided at a desired interval on the lower surface of the paint supply body 37 in a region close to the coating layer 2 or 21 or 2 formed on the upper surface 7 of the base material portion 1, and each ink ejection nozzle 38 is individually connected to the paint supply section 40. Furthermore, each ink ejection nozzle 38 may be configured so that the amount of ink protruding from each nozzle can be individually changed and adjusted at any time interval, and further, the viscosity or chromaticity of the ejected ink may be changed and adjusted at any time interval.

[0041] In this specific example, the paint supplier 37 can be moved in one direction or the opposite direction in the longitudinal direction S1 of the outer surface of the base portion 1 according to a predetermined program, or preferably in the forward and backward directions, and simultaneously or at an appropriate timing, it can be moved in one or both directions in a direction S2 perpendicular to the longitudinal direction of the outer surface of the base portion 1, thereby automatically causing the desired wood grain pattern or knot pattern to bulge and be formed with the paint 10.

[0042] Furthermore, during the above operation, by controlling the amount of ink discharged from each ink discharge nozzle 38 provided on the paint supply 37 using an appropriate program, the height, width or length of the pattern of the bulge 4 formed by the paint ink can be freely changed, making it possible to further approximate the appearance, texture or feel of natural wood. Of course, it goes without saying that the grain pattern or knot pattern according to the third aspect of the present invention can also be hand-drawn by hand.

[0043] That is, in the third aspect of the present invention, a wood-like painted member 30 is obtained in which the painted surface of the wood-like painted member 30 is formed with a wood-grain pattern portion 50 consisting of a plurality of thin linear portions of irregular width that bulge slightly upward from the painted surface 4 and that oscillate appropriately in the left and right direction, or a knotty pattern portion 51 formed by multiple overlapping ring-like portions consisting of thin linear portions of irregular width that oscillate appropriately in the left and right direction, and the original painted surface 2 of the wood-like painted member 30 and the wood-grain pattern portion 50 or the knotty pattern portion 51 are configured to be of different colors from each other.

[0044] In the third aspect of the present invention, when a coating layer 2 made of the above-mentioned synthetic resin composition for paint 10 is formed in multiple layers on the outer surface 7 of the desired substrate 1, it is a desirable example that the coating layers 2, 21, 22 for each layer are configured to differ from each other in either overall color, tone, or density. Furthermore, in the third aspect of the present invention, the wood grain pattern portion 50 and / or knot pattern portion 51 of the bulge-like 4 formed on the painted surface 2, 21, 22 may be formed by spreading or applying the wood-like painted material separately in dots or lines on the painted surface 2, 21, 22 and stretching it in a line along the surface of the painted surface using an appropriate jig.

[0045] Next, still another specific example (second specific example) of the third aspect of the present invention will be described with reference to FIG. That is, as shown in Figure 7, a substrate 1 to be painted of an appropriate shape and made of wood, synthetic resin, metal material, etc. is mounted on an appropriate fixed or movable base 60 so as to be movable in a predetermined direction on the base 60, or is fixedly held on the base 60 and arranged to move in response to movement of the base 60 in a predetermined direction D0. The outer surface of the substrate 1 to be coated is already coated with a first coating layer (intercoat layer) 2 made of the resin composition for forming a coating according to the present invention via an appropriate undercoat layer (not shown).

[0046] On the other hand, a paint supply body 37 as shown in FIG. 5 is fixedly provided at an appropriate upper portion of the moving track of the substrate 60, and the paint supply body 37 has an appropriate paint supply section 40 for supplying a second coating layer paint 10' having a different color or brightness from the resin composition constituting the first coating layer paint 10, and is provided with an ink discharge nozzle 38 formed in a slit shape on the lower surface of the paint supply body 37 for supplying the second coating layer paint 10' in a uniform film form toward the upper surface 6 of the first coating layer 2, and from the ink discharge nozzle 38, The paint 10' The ink is discharged in the form of a film to sequentially form a second coating layer 21 on the surface of the upper surface 6 of the first coating layer 2 in response to the movement of the substrate 60 . On the other hand, the paint supply body 37 of the substrate 60 Moving direction side (D0)At least one brush portion or wood grainer portion 61 manually operated by an operator is brought into contact with an appropriate portion Y1 of the second coating layer 21 formed in the paint supply body 37, and the brush portion or wood grainer portion 61 is slid in a direction (D1) away from the paint supply body 37, thereby making it possible to form an appropriate pattern, for example a wood grain pattern 50, on the second coating layer 21.

[0047] The wood grainer section 61 according to the present invention may, for example, be provided with a semi-cylindrical auxiliary section 64 at the lower end of a support plate 63 to which a handle section 62 is attached, and a pattern forming section 65 is attached to the outer surface of the semi-cylindrical auxiliary section 64, in which a plurality of curved grooves having an appropriate depth are arranged concentrically or non-concentrically. The worker holds the handle portion 62 of the wood grainer portion 61 in his / her hand, brings the wood grainer portion 61 into contact with the surface of the second coating layer 21, slides it along the longitudinal direction (P1) of the substrate 1, and moves it appropriately along the arrow P2 to another portion Y2 while rocking it appropriately, so that the paint 10 of the second coating layer 21 takes on the wood grain pattern as shown in the figure.

[0048] The brush unit or wood grainer unit 61 then returns to the initial position Y1 and repeats the above-mentioned operations. In this case, when the base material 1 is in a moving state, the moving speed of the brush unit or wood grainer unit 61 must naturally be set to be faster than the moving speed of the base material 1. Alternatively, when the brush unit is moved, the movement of the substrate 1 may be stopped. In addition, in this specific example, the wood grain pattern can be changed subtly or boldly by changing the pattern of the pattern forming portion 65 attached to the brush portion or wood grainer portion 61, by appropriately changing the linear movement speed of the brush portion or wood grainer portion 61, or by appropriately changing the swing angle and swing speed of the brush portion or wood grainer portion 61.

[0049] Furthermore, the inventors of the present application have conducted extensive research and analysis into the function and effects of the cellulose nanofiber (CNF) component in the coating agent. As well as As a result of repeating many experiments, the following new findings were obtained. In other words, one of the main purposes of mixing a cellulose nanofiber (CNF) component into a synthetic resin composition for forming a coating, including a paint, is to improve the physical properties of the synthetic resin composition for forming a coating. If we consider paint as an example, the main component of paint, both water-based and oil-based, is synthetic resin, and considering synthetic resins in general, it is expected that the same improvement in physical properties can be achieved by adding cellulose nanofiber (CNF) components to thermoplastic resin. In particular, by mixing cellulose nanofiber (CNF) components into thermoplastic synthetic resins, it has been confirmed that the resin's elasticity is improved and the flow of the resin can be improved, thereby enabling molding processes that were previously difficult to perform. It has also been confirmed that the resin has improved properties such as tensile strength, flexural strength, flexural elasticity, and deflection temperature under load.

[0050] However, even if the cellulose nanofiber (CNF) component is crushed to nano size during the manufacturing process, it can only be in a wet state if it is possible to maintain the nano size, and there is a restriction that it must be kept in a dry state when mixed with synthetic resins, etc. During this drying process, the cellulose nanofiber (CNF) components have the problem that their molecules repeatedly hydrogen bond with each other, causing them to aggregate to sizes ranging from nano to millimeter. Such aggregated cellulose nanofiber (CNF) components have the disadvantage that they have no dispersing power at all and cannot exert the effects that the original cellulose nanofiber (CNF) components should have. Therefore, to date, most of the applications of cellulose nanofiber (CNF) components have been limited to use in wet conditions, such as as a moisturizer.

[0051] Although some research has been conducted on its use in a dry state, when the wet cellulose nanofiber (CNF) components are dried, it is necessary to drastically slow down the speed of the drying process in order to prevent hydrogen bonding of the cellulose nanofiber (CNF) components and to adopt measures to minimize re-agglomeration of the cellulose nanofiber (CNF) components, making this unrealistic in terms of mass production and cost. In order to solve these conventional problems, the inventors of the present application conducted further intensive research and discovered a technology that enables mass-producible aggregated cellulose nanofiber (CNF) components to be opened with water-soluble cellulose, thereby enabling the opened state to be maintained within the synthetic resin component even in a dry state, thereby achieving mass productivity and realistic costs. This new technical concept has made it possible to uniformly mix components such as wood flour into water-based paints, oil-based paints, thermoplastic resins, and thermosetting resins.

[0052] As the water-soluble cellulose that can be used in the present invention, for example, carboxymethyl cellulose (CMC) is preferably used. On the other hand, the inventors of the present application have further conducted intensive research into improving the dispersion performance of the cellulose nanofiber (CNF) component itself in a liquid or a synthetic resin component when producing the synthetic resin composition for forming a coating, and as a result of carrying out and analyzing a large number of comparative experiments, have found that the cellulose nanofiber (CNF) component Water-soluble cellulose For example, it has been discovered that a cellulose component in which the hydroxyl groups (OH groups) of ordinary cellulose have been replaced with methyl groups (CH3 groups) has the function of uniformly dispersing each cellulose nanofiber (CNF) component in the solvent or aqueous solution, thereby reliably preventing aggregation of the cellulose nanofiber (CNF) components.

[0053] On the other hand, the inventors of the present application have found that, in the second embodiment of the present invention, when producing a resin composition for forming a coating containing the paint and containing the wood flour or shavings, the wood flour or wood shavingsAt the same time, it was also found that in order for the components in the mixture, in which the aqueous solution or synthetic resin and the cellulose nanofiber (CNF) component are mainly mixed, to be mixed uniformly with each other, the process of stirring the mixture is extremely important; for example, in a stirring device for stirring the mixture, simply stirring the mixture put into the stirring device with a stirring device having a conventionally known stirring blade does not achieve the expected sufficient fiber-opening effect of the cellulose nanofiber (CNF) component, and therefore, it was found that the expected fiber-opening and dispersion effects can be obtained by imparting a new and special function to the stirring device. In other words, one preferred example is to use in the stirring device a stirring blade or a stirring rod with a special mechanism that can impart a shearing effect to the resin components, wood flour, cellulose nanofiber (CNF) components, etc.

[0054] As an example of the stirring device capable of exerting the shearing effect used in the present invention, it is desirable to use a mixing device equipped with multiple blades having a special shape, as disclosed in Japanese Patent No. 6163172 by Akihiko Koga, one of the inventors of the present application. In other words, when a propeller-type screw is used to mix the CNF (fine fibers, etc.) into a liquid, it is known that when shear force is applied to the CNF (fine fibers, etc.) during mixing, the fine fibers are uniformly dispersed and mixed. For this reason, in the above specific example as well, the propeller portion of the propeller-type screw is configured so that its tip is thin like a blade, and is designed to generate high shear force. However, with this method, there is a tendency for the shear force to be poorly transmitted to the liquid itself. To improve this, it is also possible to adopt a method of uniformly dispersing and mixing the CNF (fine fibers, etc.) using a mixing device configured to apply a shear force to the liquid itself using a hollow cylindrical rotor instead of the specially shaped propeller structure described above. In other words , to liquid As an efficient method for uniformly dispersing and mixing CNF (fine fibers, etc.), When liquid is mixed by applying shear force It is known that uniform dispersion is possible. In other words, in the present invention, when a water-soluble resin composition is used, it is desirable to employ a mechanism having a shear structure in the mixing screw, and when a thermoplastic resin composition is used, it is desirable to employ a screw design having a shear structure or a resin melting method using frictional heat generated by the high speed rotation of a shear screw for mixing processing.

[0055] Hereinafter, still another embodiment (third embodiment) of the present invention will be described. In this specific example, the above-mentioned synthetic resin component 10 for forming a coating of the present invention is used as a paint material and uniformly applied to the surface of a substrate 1 made of an aluminum plate to form a first coating layer 2, and then the synthetic resin component 10' for forming a coating is uniformly applied to the upper surface of the first coating layer 2 to form the second coating layer 21, and then a pattern portion 50 including an appropriate wood grain pattern is formed on the surface of the second coating layer 21 using an appropriate brush, comb or trowel, or an appropriate wood grainer 61. Specifically, an aluminum plate having a predetermined width and length was prepared as the base portion 1 . (Undercoat process) Next, as an undercoat process, a undercoat treatment was performed on one surface of the base part 1 using an undercoat agent made by mixing an epoxy resin paint with 20 parts by weight of a diluent for every 100 parts by weight of the epoxy resin paint, so that the film thickness of the undercoat agent was 15 to 25 μm. (Intermediate coating process)

[0056] Then, in the intermediate coating step, the synthetic resin 10 for forming a coating according to the present invention, which is a mixture of 100 parts by weight of a urethane-based synthetic resin, 0.5 parts by weight of the cellulose nanofiber (CNF) component, 1.0 part by weight of 100 μm wood powder, 1.0 part by weight of water-soluble cellulose (CMC), and 40 parts by weight of a dilution solvent, is applied as an intermediate coating agent to the surface of the base part 1 that has been subjected to the undercoating treatment, The film thickness is 30 to 40 μm. Thus, the first coating layer 2 was formed. (Baking and drying process) Thereafter, the treated product was subjected to a baking and drying treatment at a temperature of 160°C to 190°C for 20 minutes.

[0057] (Topcoat process) Next, in the undercoat process, a pattern forming layer 21 for forming appropriate patterns 50, 51, etc. by swelling 4 on the upper surface of the first coating layer 2 is formed using a coating-forming resin composition obtained by mixing a urethane-based synthetic resin having a color or hue different from that of the first coating layer 2 with 1.0 part by weight of a thickener and 20 parts by weight of a diluting solvent for 100 parts by weight of the urethane-based synthetic resin. (Applying amount uniformity process) Thereafter, the surface of the pattern-forming layer 21 is scraped using an appropriate spatula device, brush device or appropriate flattening means to flatten the surface of the pattern-forming layer 21 and at the same time make the thickness of the pattern-forming layer 21 uniform.

[0058] (Patterning process) Next, as quickly as possible after the above-mentioned coating amount uniformization process is completed, preferably within one minute, a suitable wood grainer means having a rubber trowel or spatula portion for forming a suitable pattern, or a pattern portion for forming a suitable pattern, is brought into contact with the surface of the pattern forming layer 21 and moved in a predetermined direction to form, for example, a suitable wood grain pattern. (Baking and drying process) Thereafter, the substrate 1 on which the wood grain pattern was formed was subjected to a baking and drying process at a temperature of 160° C. to 190° C. for a setting time of 20 minutes. Furthermore, as another specific example of the present invention, between the above-mentioned application amount uniformization process and the patterning process, it is also possible to insert a process of applying, in dots, a resin composition having a color or chromaticity different from the color or chromaticity of the resin composition of the pattern-forming layer 21, for example a composition mainly composed of a urethane-based synthetic resin, as a paint onto the pattern-forming layer 21 in order to apply a pattern. This operation is called the drip process (dotting process).

[0059] (Drip process) In the drip process, a drip-forming resin composition, which is a mixture of urethane-based synthetic resin, 1.0 part by weight of thickener, and 20 parts by weight of dilution solvent for 100 parts by weight of the urethane-based synthetic resin, is used, and a process is carried out in which a predetermined amount of the drip-forming resin composition is placed at a predetermined location on the surface of the pattern-forming layer 21 using an appropriate drip supply means. Thereafter, the base part 1 with the resin composition for forming droplets attached thereto in such dot-like form is transferred to the patterning process described above, in which the resin composition for forming droplets arranged in such dot-like form is deformed to form the desired wood grain pattern, and then the base part 1 is transferred to a baking and drying process to complete the process. Please refer to Table 1 for specifications of each process in the above-mentioned embodiment of the present invention.

[0060] In Table 1 below, the "Ratio" column indicates the weight ratio (wt%) of each component used in the third embodiment, and the "Scope of Application" column indicates the weight ratio (wt%) of each other component that may be used in the third embodiment when the resin component is 100 parts by weight. [Table 1] FIG. 8 shows an electron microscope photograph of the first resin composition for forming a coating film 10 according to the present application produced by the third specific example.

[0061] As shown in FIG. 8 and with reference to FIG. 9, the first resin composition for forming a coating film obtained by this specific example has wood powder 14 broken down and crushed into fine particles in the urethane resin component 10 as the base material, and these particles are present in a substantially uniformly dispersed state at a certain distance from each other without agglomerating with each other. Similarly, it can be seen that the cellulose nanofiber (CNF) component 15 and the water-soluble cellulose component (e.g., CMC) 17 are present in an approximately uniformly dispersed state without agglomerating with each other, and in particular, it can be seen that the cellulose nanofiber (CNF) component is uniformly dispersed and arranged in an open-ended state near the periphery of the wood flour 14.

[0062] Here, if we consider the wood-like painted members of the present application according to the third specific example and the two specific examples mentioned above, the effect of mixing a cellulose nanofiber (CNF) component into a coating material containing a wood powder material is that, in addition to the effect of preventing the aggregation of wood powder mentioned above, fluidity is improved, thereby making it easier to apply, and as a result, the hardness of the resin itself is improved, which also improves the strength of the coating film formed. Furthermore, a more significant effect obtained by the present invention is that the weather resistance of the coating film itself formed from the coating resin composition is significantly improved. Specifically, the weather resistance of the coating material is such that it can exhibit excellent resistance to deterioration caused by ultraviolet rays.

[0063] On the other hand, in the present invention, a paint containing the cellulose nanofiber (CNF) component can be applied to the surface of the base part 1 that is exposed to ultraviolet rays, or can be applied between or beneath multiple laminated coating layers. Another example is when a wooden bench is used outdoors, for example, a paint containing the cellulose nanofiber (CNF) component is directly applied to the wooden bench. How to improve weather resistance One method to improve weather resistance is to apply a paint containing the cellulose nanofiber (CNF) component to a base and then apply a regular paint. In addition, when painting steel parts, it has been confirmed that if the cellulose nanofiber (CNF) component is added to the rust-preventive paint applied to the base coat, the rust-preventive effect of the steel is improved and the weather resistance of the top coat of paint is also improved.

[0064] On the other hand, when the properties of a wood-like painted member according to the present application, in which a coating was formed on an appropriate aluminum plate according to the above-mentioned third embodiment (specific example), were compared with those of the same aluminum substrate, in which a coating was formed using the coating resin composition not containing the cellulose nanofiber (CNF) component in the above-mentioned third embodiment (specific example), almost no difference was observed in the test items of gloss, impact resistance, alkali resistance, acid resistance, boiling resistance, and accelerated weather resistance between the two samples. However, in terms of hardness, the sample of the present invention showed a hardness of 5H, while the comparative product showed, The hardness is only 4H. Furthermore, in a salt damage resistance test in which salt water was sprayed, the sample of the present invention showed no peeling of the coating even after more than 1,000 hours of testing, whereas the comparative product showed peeling of the coating after 500 hours.

[0065] Judging from the results of the above comparative experiments, the wood-like painted member according to the present invention has the following characteristics: It was found that the product had superior hardness and was more resistant to salt damage than the same product coated with the same resin composition for forming a film that did not contain cellulose nanofiber (CNF) components. Therefore, it is believed that the resin composition for forming a coating according to the present invention is effective not only as a coating material but also as a rust inhibitor and a treatment agent for preventing salt damage. [Explanation of symbols]

[0066] 1 Base material 2 Coating layer, first paint layer 3. Surface of the coating layer 4 Bulge 5. Depressed linear portion 6 Paint film 7 Outer surface of the base material 7' the outer surface of the coating layer 21; 7″ Outer surface of coating layer 22 10. Synthetic resin composition, synthetic resin composition for wear 11 Synthetic resin components 12 Pigments 13 Solvent components 14 Wood flour components 15 Cellulose nanofiber (CNF) component 16 Air Fresheners 21 Second paint layer 22 Third paint layer 30 Wood-like painted materials 35 Formwork or pattern frame 36 Thin line part 37 Paint supply body 38 Ink ejection nozzle 40 Paint supply section 50 Wood grain pattern 51 Knotty pattern 60 Substrates 61 Brush section or wood grainer section 62 Handle 63 Support plate 64 Semi-cylindrical auxiliary part 65 Pattern forming section

Claims

1. A synthetic resin composition for forming a coating, comprising at least a synthetic resin component, a wood flour component, a cellulose nanofiber (CNF) component and water-soluble cellulose, wherein the composition ratio of each of the components in the synthetic resin composition is set to 0.3 to 10 parts by weight of the wood flour component, 0.5 to 10 parts by weight of the cellulose nanofiber (CNF) component, and 0.1 to 2 parts by weight of the water-soluble cellulose, relative to 100 parts by weight of the synthetic resin component, and wherein the wood flour component is uniformly dispersed within the synthetic resin composition.

2. 2. The synthetic resin composition for forming a coating according to claim 1, wherein the cellulose nanofiber component functions as a dispersing agent for dispersing the wood flour component within the synthetic resin composition.

3. The synthetic resin composition for forming a coating as described in claim 1, characterized in that the water-soluble cellulose is carboxymethyl cellulose (CMC).

4. A synthetic resin composition for forming a coating as described in claim 1, further comprising an aromatic component that gives off a wood aroma.

5. A synthetic resin composition for forming a coating according to any one of claims 1 to 4, characterized in that the synthetic resin composition for forming a coating functions as an oil-based paint.

6. A synthetic resin composition for forming a coating according to any one of claims 1 to 4, characterized in that the synthetic resin composition for forming a coating functions as a water-based paint.

7. A method for producing a synthetic resin composition for forming a coating, comprising: mixing a desired amount of a cellulose nanofiber component and a water-soluble cellulose component into a desired synthetic resin component dissolved in an appropriate solvent, carrying out a stirring process, mixing a desired amount of wood powder into a synthetic resin composition consisting of the synthetic resin component containing the cellulose nanofiber component and the water-soluble cellulose component, and then stirring the synthetic resin composition for a desired period of time using a mixing device having a mixing screw portion configured to apply a shear force to the synthetic resin composition.

8. A wood-like painted member having at least one coating layer formed on the outer surface of a desired substrate, the coating layer being made of the synthetic resin composition for forming a coating described in any one of claims 1 to 6, wherein the outer surface of the coating layer in the painted member has a feel, texture and roughness that is approximately similar to the feel, texture and roughness of natural wood.

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