JP7656433B2 - Painting resin composition containing wood powder, its manufacturing method, and wood-like painted member coated with the painting resin composition - Google Patents

Description

The present invention relates to a resin composition for coating containing wood powder, a method for producing the same, and a wood-like painted member coated with the resin composition for coating. More specifically, the present invention relates to a resin composition for coating containing a mixture of wood powder and a cellulose nanofiber (CNF) component in a synthetic resin component, a wood-like painted material in which the wood powder is dispersed in a substantially uniform manner in the synthetic resin component, and a wood-like painted member coated with the wood-like painted material.

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 this situation, as a means of meeting the demand for wood while anticipating a decrease in production, there is a demand for the production and utilization of recycled wood by recycling used or waste wood, and for the production of artificial wood by using non-wood materials.

Methods for recycling such discarded wood include, for example, a method of applying a paint that gives the surface of the discarded 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). Also known is a method of producing 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 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. 3,030,009 (Patent Document 6).

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.

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 natural wood and actively utilize this 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 will be prevented from agglomerating together in the synthetic resin component to form large lumps, and the wood flour or sawdust will be controlled so that it is individually and independently dispersed and uniformly present in the synthetic resin component, and the new paint will be able to be easily and efficiently applied to the surface of waste wood, metal materials, or synthetic resin materials, regardless of the painting method .

Japanese Patent Application Laid-Open No. 59-19236 JP 2000-343030 A JP 2009-209237 A JP 2015-137340 A JP 2008-120019 A Patent No. 3030009

The object of the present invention is therefore to provide a synthetic resin composition, such as a paint, in which fine wood powder or sawdust is individually and independently dispersed and uniformly mixed in the desired synthetic resin composition without agglomeration, easily and inexpensively, 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, such as a paint, which has a wood-like appearance and a texture and feel that are similar to the texture and feel of natural wood.

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.
That is, 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 embodiment of the present invention is primarily used for painting, but can also be used for purposes other than painting, as described below.

The synthetic resin composition for forming a film according to the present invention is a synthetic resin composition for forming a film in which fine wood powder or sawdust is individually and independently dispersed and mixed uniformly in the desired synthetic resin composition without coagulation, compared to conventional coating materials of the same type. For example, when used for painting, it is possible to provide painting work easily and inexpensively. Furthermore, compared to conventional paints that give the texture, appearance, and feel of wood materials, a coating material is obtained that can form a coating that is full of luxury and can reveal the appearance, texture, and feel of natural wood more than paints that have been known to date, and it is possible to not only regenerate waste wood, but also easily produce artificial wood by applying paint to the surface of a metal or synthetic resin substrate, so that it is possible to provide a paint that reduces the consumption of natural wood, contributes to the promotion of the preservation of forest systems and the prevention of natural disasters, and can also greatly contribute to the prevention of air pollution and global warming.

FIG. 1 is a schematic diagram for explaining the outline of the constitution of the synthetic resin composition for forming a coating film used in the present invention. FIG. 2 is a perspective view illustrating an outline of a wood-like painted member obtained according to the present invention. FIG. 3 is a cross-sectional view for explaining an outline of a specific configuration of a wood-like painted member obtained according to the present invention. FIG. 4 is a cross-sectional view for explaining the outline of the structure of another embodiment of the wood-like painted member obtained by the present invention. FIG. 5 is a diagram for explaining 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 the coating process of the present invention. FIG. 6 is a diagram for explaining 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 the coating process of the present invention. FIG. 7 is a diagram for explaining 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 the coating process in the present invention. FIG. 8 is an electron microscope photograph of the synthetic resin composition for coating used in the present invention. FIG. 9 is a reference diagram for explaining the electron microscope photograph of FIG.

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.

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 component made of a synthetic resin material or a metal material.

As already pointed out above, it is already known that wood powder 14 such as cellulose fiber or sawdust is mixed into a general paint, and then dried or baked as appropriate after application to volatilize or evaporate the solvent, thereby forming a solid layer coating 6 with a wood grain pattern 50 as shown in FIG. 2, thereby appropriately changing the surface appearance, touch or texture of the substrate 1 to a wood-like appearance, touch or texture, and using the substrate as recycled wood. However, in such conventional technology, when wood powder or cellulose fiber is mixed into the paint 10, the wood powder or cellulose fiber often aggregates and forms large lumps. Therefore, even if a paint in such a state is used, many large lumps of wood powder or cellulose fiber remain on the surface of the completed coated body, which is completely different from the surface appearance, touch 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.

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 a 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.

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, as shown in Figure 1, when mixing the wood flour or plank shavings 14, etc. into the synthetic resin component 11 of the paint component, by mixing an appropriate amount of cellulose nanofiber (CNF) component 15, 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 etc. component 14 uniformly and independently within the synthetic resin composition.

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.

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.

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 powder or sawdust 14 used in the present invention is not particularly limited, but may be, for example, 20 to 200 μm in grain size, preferably about 50 μm.

Furthermore, the pigment 12, hardener, additives, and the like 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 in general, it is 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.

In the synthetic resin composition 10 for forming a coating according to the present invention, the inventors of the present application analyzed the cause of the wood flour or sawdust 14, etc. being individually and independently uniformly dispersed in the synthetic resin component 10 with reference to the results of many experiments. 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 in the synthetic resin composition 10 containing the synthetic resin 11, so that multiple cellulose nanofiber (CNF) components 15 are arranged near the peripheral edges of the wood flour or sawdust, etc. 14, and it was understood that the cellulose nanofiber (CNF) component 15 effectively prevents multiple pieces of wood flour, etc. 14 from approaching each other and joining/aggregating to form large lumps in the synthetic resin composition.

That is, as shown in FIG. 1, the synthetic resin composition for coating (paint) 10 according to the present invention is arranged in a solvent 13 with a mixture of multiple synthetic resin components 11, pigment components 12, and wood flour components 14, 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 are surrounding the wood flour components 14. It is believed that this structure 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.

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.

Furthermore, when the synthetic resin composition 10 for forming a coating according to the present invention 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 constituting waste wood in order to regenerate the surface of the waste wood. In addition, 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 which looks or feels like natural wood in terms of appearance, texture, and feel, even though the substrate member 1 is a non-woody material.

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 stabilizing effect.
Furthermore, the synthetic resin composition 10 for forming a coating 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.

On the other hand, the synthetic resin composition 10 for forming a coating according to the present invention can of course 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.

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, and is characterized in that it basically includes 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.

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, a 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.

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 for forming a coating film 10 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.

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 a coating 10, a method is also possible in which the same brownish pigment having a different saturation or brightness is used in another synthetic resin composition for forming a coating 10'. Also, different synthetic resin compositions for forming coatings 10, 10', 10", ... may be produced by using pigments having mutually different hues as pigments.
In other words, in the present invention, other synthetic resin compositions 10', 10" and the like for forming coatings, which have a color with a different saturation or lightness from that of the synthetic resin composition 10 for forming coatings having a basic wood-like color or lightness, are used as synthetic resin compositions for forming a wood-like pattern, as described later.
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.

Next, a specific technical configuration relating to the third aspect of the present invention will be described in detail with reference to FIGS.
That is, 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 for coating 10 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 for coating 10 is formed, and the outer surface 31 of the coating layer 2 in the painted member 30 has a feel, texture, and roughness that is approximately similar to the feel, texture, and roughness of natural wood.

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 utilizing an appropriate coating means to form a coating layer 2 having a uniform thickness, and then, via an appropriate baking 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 body 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.

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.

The wood-like painted component 30 formed by the third aspect has the wood powder 14 contained in the paint uniformly dispersed on the painted surface, so that a wood-like painted component 30 is provided that has a woody appearance and a texture and feel that are similar to the texture and feel of natural wood.
Therefore, the wood-like painted member 30 obtained by the present invention has a very 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.

In the third embodiment of the present invention, when manufacturing the wood-like painted member 30, for example, as shown in FIG. 3, when the paint composed of the synthetic resin composition for painting 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 layer of paint layer 2 on the outer surface 7 of the substrate 1. Alternatively, as another embodiment, as shown in FIG. 4, when the paint composed of the synthetic resin composition for painting 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 applied in multiple layers on top of the first paint layer 2 formed on the outer surface 7 of the substrate 1.

In such a specific example, preferably, when a plurality of coating layers 2, 21, 22, ... 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 concentration.
When the above-mentioned synthetic resin composition for coating 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 coating containing wood powder 10 to form a first coating layer 2 (also referred to as an undercoat step).

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 are generally referred to as a topcoat treatment step.
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 wood-like shape on its outer surface 7, but the color itself is monochromatic, and therefore does not have the same grain or knot patterns as actual natural wood. As a result, the member has a bland appearance, which results in little commercial value.
Therefore, in the present invention, when applying an appropriate pattern including a wood grain pattern to the second paint layer 21 or the third 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 paint brush, bristle, 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 adopt a method in which an appropriate pattern is applied from the beginning, as illustrated in Figure 5, to directly form an appropriate bulge-like pattern 50.
In this treatment process, the thickness of the coating in the undercoat process is generally 15 to 25 μm, the thickness of the coating in the intermediate coat process is generally 30 to 40 μm, and the thickness of the coating in the top coat process is generally 0.05 mm to 1.0 mm.

In other words, in the third aspect of the present invention, as shown in FIG. 4, a preferred embodiment is to use the synthetic resin composition 10 for painting 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 that resembles that of 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.

On the other hand, in the third embodiment of the present invention, when a plurality of paint layers are formed on the outer surface 7 of the base portion 1, as shown in Figure 6, a formwork or pattern frame 35 having a portion 36 in which a suitable wood grain pattern or knot pattern is cut out of the surface of the paint layer 21 or 22 forming the uppermost layer is used to cut out the surface of the paint layer 21 or 22 in the shape of that pattern, and a recessed linear portion 5 as shown in Figure 3 or Figure 4 is formed to form an imitation wood grain or knot pattern, or the paint according to the present invention described above is applied and printed along the cuts to create a wood grain pattern, which is another preferred example.
In such a specific example, it is desirable to use a pigment having a darker hue in the paint layer of the paint layer 21 or 22 constituting the upper layer portion than the pigment in the paint layer of the paint layer 2 or 21 constituting the lower layer portion.

In the third aspect 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 formed by bulging on the coating layer 2 formed on the outer surface of the suitable fuselage section 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 section 1, using a paint which is the synthetic resin composition for coating 10, the paint may be configured to form a bulging pattern using the paint 10 using a paint supplier 37 which is provided close to the upper surface 7 of the base section 1 on which the desired coating layer 2 is formed, along the surface of the coating layer 2 in the longitudinal direction (S1) of the base section, and which is also provided so as to be movable in the direction (S2) perpendicular to the longitudinal direction of the base section, as shown in FIG. 5, for example.

In this specific example, the paint supply body 37 has the paint supply section 40, and at least one, preferably multiple ink ejection nozzles 38 are provided at desired intervals on the underside of the paint supply body 37 in close proximity to the coating layer 2 or 21 or 2 formed on the upper surface 7 of the substrate 1, and each ink ejection nozzle 38 is individually connected to the paint supply section 40. Each ink ejection nozzle 38 may be configured so that the amount of ink ejected 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.

In this specific example, the paint supply body 37 can be moved in one direction or the opposite direction in the longitudinal direction S1 of the outer surface of the base part 1 according to a predetermined program, or preferably in the forward and backward directions, while simultaneously or at an appropriate timing, it can be moved in one or both directions in the direction S2 perpendicular to the longitudinal direction of the outer surface of the base part 1, thereby automatically forming a bulge with the paint 10 as desired.

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.

In other words, in the third aspect of the present invention, 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-right direction, or a knotty pattern portion 51 formed by overlapping ring-shaped portions consisting of thin linear portions of irregular width that oscillate appropriately in the left-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 formed in different colors from each other, resulting in a wood-like painted member 30.

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 linearly along the surface of the painted surface using an appropriate jig.

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).

On the other hand, a paint supply body 37 as shown in Figure 5 is fixedly provided at an appropriate upper portion of the movement path 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 is configured to discharge the paint 10' in a film form from the ink discharge nozzle 38 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, by abutting at least one brush portion or wood grainer portion 61 manually operated by an operator against an appropriate portion Y1 of the second coating layer 21 formed on the paint supply body 37 in the movement direction side (D0) of the substrate 60, and sliding the brush portion or wood grainer portion 61 in a direction (D1) away from the paint supply body 37, it is possible to form an appropriate pattern, for example a wood grain pattern 50, on the second coating layer 21.

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

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 base material 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.

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, and have conducted numerous experiments, resulting in the following new findings:
That is, one of the major purposes of mixing a cellulose nanofiber (CNF) component into a synthetic resin composition for forming a coating film, including a paint, is to improve the physical properties of the synthetic resin composition for forming a coating film.
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 flow can be improved and that this improves the resin's elasticity, making it possible to carry out molding processes that were previously difficult. It has also been confirmed that this improves properties such as tensile strength, flexural strength, flexural modulus, and deflection temperature under load.

However, even if the cellulose nanofiber (CNF) component is pulverized to nano size during the manufacturing process, it is limited to being in a wet state only if it is possible to maintain the nano size, and when it is mixed with synthetic resins, etc., there is a restriction that it must be kept in a dry state.
In the drying process, the cellulose nanofiber (CNF) components have the problem that their molecules repeatedly form hydrogen bonds 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, up until now, most of the applications of cellulose nanofiber (CNF) components have been limited to applications such as moisturizers used in wet conditions.

Although some research has been conducted on its use in a dry state, when the wet cellulose nanofiber (CNF) component is dried, it is required to drastically slow down the speed of the drying process in order to prevent hydrogen bonding of the cellulose nanofiber (CNF) component and to adopt measures to minimize re-agglomeration of the cellulose nanofiber (CNF) component, which makes this unrealistic in terms of mass production, cost, etc.
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.

As the water-soluble cellulose that can be used in the present invention, for example, carboxymethyl cellulose (CMC) is preferably used.
Meanwhile, in producing the synthetic resin composition for forming a coating, the inventors of the present application continued to thoroughly study how to improve the dispersion performance of the cellulose nanofiber (CNF) component itself in a liquid or synthetic resin component, and as a result of carrying out and analyzing numerous comparative experiments, they discovered that adding water-soluble cellulose to the cellulose nanofiber (CNF) component, for example a cellulose component in which the hydroxyl groups (OH groups) of ordinary cellulose are replaced with methyl groups ( _CH3 groups), has the function of uniformly dispersing each of the cellulose nanofiber (CNF) components in the solvent or aqueous solution, thereby reliably preventing the cellulose nanofiber (CNF) components from agglomerating together.

On the other hand, the inventors of the present application have also found that when producing the resin composition for forming a coating containing the paint containing the wood flour or shavings, etc., which is the second aspect of the present invention, in order for the components in the mixture in which the wood flour or shavings , the aqueous solution or synthetic resin, and the cellulose nanofiber (CNF) component, etc. are mainly mixed together 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 provide the expected sufficient fiber-opening effect of the cellulose nanofiber (CNF) component, and therefore, the expected fiber-opening and dispersion effects can be obtained by imparting a new and special function to the stirring device.
That is, one preferred example is to use in the stirring device a stirring blade or a stirring rod having a special mechanism capable of imparting a shearing effect to the resin component, wood flour, cellulose nanofiber (CNF) component, etc.

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. 6,163,172 by Akihiko Koga, one of the inventors of the present application.
In other words, when a propeller-type screw is used to mix 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 shear force to the liquid itself using a hollow cylindrical rotor, instead of the specially shaped propeller structure described above.
In other words , it is known that an efficient method for uniformly dispersing and mixing CNF (fine fibers, etc.) in a liquid is to apply shear force to the liquid while mixing, which enables uniform dispersion.
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.

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, an undercoat treatment was performed on one surface of the base part 1 using an undercoat agent obtained by mixing an epoxy resin paint with 20 parts by weight of a diluent per 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)

Thereafter, in the intermediate coating process, the synthetic resin for forming a coating 10 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 undercoat treatment, and the first paint layer 2 is formed so as to have a film thickness of 30 to 40 μm .
(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.

(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 paint 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 the color or hue of the first paint layer 2 with 1.0 part by weight of a thickener and 20 parts by weight of a dilution solvent for 100 parts by weight of the urethane-based synthetic resin.
(Coating amount uniformization 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.

(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 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 (dot pattern process).

(Infusion process)
In the drip process, a drip-forming resin composition obtained by mixing a urethane-based synthetic resin 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 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.

上記第３の具体例により製造された本願に於ける当該第１の被膜形成用樹脂組成物１０の電子顕微鏡写真を図８に示す。 In Table 1 below, the "Ratio" column indicates the weight ratio (wt%) of each component used in the third embodiment, and the "Applicable Range" 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.

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 embodiment described above.

As shown in FIG. 8 and with reference to FIG. 9, the first resin composition for forming a coating 10 obtained by this specific example has wood powder 14 decomposed 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-open state near the periphery of the wood flour 14.

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, there is also the effect of improving fluidity, thereby making it easier to apply, and as a result, there is the effect of improving the hardness of the resin itself, thereby improving the strength of the coating 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.

On the other hand, in the present invention, the 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.
As another example, in the case of using a wooden bench outdoors, there is a method in which a paint containing the cellulose nanofiber (CNF) component is directly applied to the wooden bench to increase its weather resistance, and a method in which a paint containing the cellulose nanofiber (CNF) component is applied as a base and then a normal paint is applied to improve weather resistance.
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.

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 a hardness of only 4H. Furthermore, in a salt damage resistance test in which salt water was sprayed, the sample of the present invention did not show peeling of the coating even after more than 1000 hours of testing, while peeling of the coating was observed in the comparative product after 500 hours.

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.

Reference Signs List 1: Substrate 2: Coating layer, first coating layer 3: Surface portion of coating layer 4: Bulging portion 5: Depression-like linear portion 6: Coating film 7: Outer surface 7' of substrate portion: Outer surface of coating layer 21,
7″ Outer surface of coating layer 22 10 Synthetic resin composition, synthetic resin composition for application 11 Synthetic resin component 12 Pigment 13 Solvent component 14 Wood powder component 15 Cellulose nanofiber (CNF) component 16 Fragrance 21 Second coating layer 22 Third coating layer 30 Wood-like coating member 35 Formwork or pattern frame 36 Thin line portion 37 Paint supply body 38 Ink ejection nozzle 40 Paint supply section 50 Wood grain pattern section 51 Knot pattern section 60 Substrate 61 Brush section or wood grainer section 62 Handle section 63 Support plate 64 Semi-cylindrical auxiliary section 65 Pattern forming section

Claims (8)

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. The synthetic resin composition for forming a coating according to claim 1, characterized in that the cellulose nanofiber component functions as a dispersing agent for dispersing the wood flour component within the synthetic resin composition. 2. The synthetic resin composition for forming a coating film according to claim 1, wherein the water-soluble cellulose is carboxymethyl cellulose (CMC). 2. The synthetic resin composition for forming a coating film according to claim 1, further comprising an aroma component for releasing a wood aroma. 5. The synthetic resin composition for forming a coating film according to claim 1, which functions as an oil-based paint. 5. The synthetic resin composition for forming a coating film according to claim 1, which functions as a water-based paint. 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 section configured to apply a shear force to the synthetic resin composition. 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 as described in any one of claims 1 to 6, and characterized in that 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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