Painted wood material and method for manufacturing the same

Abstract

A method for manufacturing painted wood-based materials that retain the natural appearance inherent to wood, and the provision of painted wood-based materials. [Solution] A method for manufacturing painted wood material, comprising the steps of: applying a water-based resin paint to the surface of an unpainted wood material 11 and drying it to form a penetration-inhibiting layer 12; and applying a surface resin paint to the surface of the penetration-inhibiting layer 12 and drying it to form a surface coating layer 13. Preferably, the difference between the brightness measured on the surface of the surface coating layer 13 and the brightness measured on the surface of the wood material 11 after the surface coating layer 13 and the penetration-inhibiting layer 12 have been removed is 5.0 or less.

Description

Technical Field

[0001] The present invention relates to a painted wood material and a method for manufacturing the same.

Background Art

[0002] For housing building materials such as floors and walls, and furniture such as tables and chairs, painted wood materials obtained by applying paint to wood materials are used. Wood materials include not only solid wood, but also wood veneers obtained by attaching wood surface materials such as sliced veneer or veneer to a base material. Painting is performed for the purpose of enhancing surface performance (such as stain resistance, scratch resistance, chemical resistance, antibacterial and antiviral properties, etc.) and improving the appearance properties. When paint is applied to the surface of a wood material, the resin penetrates and the surface color tone changes to a darker, wet color. The wet color has conventionally been recognized as an appearance that evokes a sense of luxury, but recently, there has been an increasing demand for wood materials that are close to the original color tone of wood.

[0003] For example, Patent Document 1 discloses a wood material provided with high refractive index particles (such as titanium oxide) along the surface of a resin impregnated layer for the purpose of providing a coated wood material in which the appearance color tone is not easily darkened even when the wood material is impregnated with resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the invention of Patent Document 1, it is possible to prevent the surface color tone from darkening due to the penetration of the resin, but the appearance becomes different from the original appearance of the wood. In addition, when the paint is chipped or damaged, there is a possibility of a difference in brightness.

[0006] One of the objects of the present invention is to provide a painted wood material having the natural appearance of the original wood and a method for manufacturing the same. [Means for solving the problem]

[0007] The present invention is summarized in the following (1) and (2).

[0008] (1) A method for manufacturing painted wood material, comprising the steps of: applying a water-based resin paint to the surface of wood material and drying it to form a penetration-inhibiting layer; and applying a surface resin paint to the surface of the penetration-inhibiting layer and drying it to form a surface coating layer.

[0009] (2) A painted wood material comprising a penetration-inhibiting layer formed on the surface of the wood material and a surface coating layer formed on the surface of the penetration-inhibiting layer, wherein the difference between the brightness measured on the surface of the surface coating layer and the brightness measured on the surface of the wood material after the surface coating layer and the penetration-inhibiting layer have been removed is 5.0 or less. [Effects of the Invention]

[0010] According to the present invention, a painted wood material can be obtained that has the natural appearance inherent to wood. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows a schematic diagram of painted wood material. [Modes for carrying out the invention]

[0012] [Wood material] The painted wood material 10 comprises a penetration-inhibiting layer 12 formed on the surface of the wood material 11 and a surface coating layer 13 formed on the surface of the penetration-inhibiting layer 12.

[0013] (wood material 11) Wood material 11 refers to wood material that has not been treated with resin, such as resin impregnation or painting (hereinafter also referred to as "unpainted wood material"). In other words, wood material 11 is a material that retains the color derived from the wood material itself. Examples of wood material 11 include solid wood and composite wood material in which a surface decorative material is attached to a base material using adhesive. Examples of base materials include plywood, laminated wood, fiberboard, wood fiberboard, gypsum board, and resin board. Examples of surface decorative materials include sawn veneer and other wood materials. There are no restrictions on the thickness of the surface decorative material, but for example, it is 0.2 mm or more. However, if the surface decorative material is thin, the influence of other components (for example, the color of the base material or adhesive, and trace amounts of water-based resin paint or surface resin paint that have penetrated it) becomes greater, so the discoloration suppression effect by forming the penetration-inhibiting layer 12 is less likely to appear. Therefore, the thickness of the surface decorative material is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. The surface decorative material may be made by bonding multiple materials together in the width direction or length direction by edge gluing, length splicing, etc., for example, laminated wood.

[0014] (Penetration-inhibiting layer 12) The penetration-inhibiting layer 12 is a layer formed on the surface of the wood material 11. The penetration-inhibiting layer 12 can suppress discoloration of the wood, i.e., wet color, caused by the paint penetrating the wood material 11 when forming the surface coating layer 13.

[0015] When the surface coating layer 13 is applied, if it passes through the penetration-inhibiting layer 12 and reaches the wood material 11 and penetrates, a wet color caused by the surface coating layer 13 may occur even if the penetration-inhibiting layer 12 itself does not penetrate the wood material 11. For this reason, it is preferable that the penetration-inhibiting layer 12 is composed of a film that suppresses the passage of the surface coating layer 13 and inhibits the penetration of the surface coating layer 13 into the wood material 11.

[0016] Examples of resins constituting the penetration-inhibiting layer 12 include urethane resins, acrylic resins, acrylic urethane resins, etc. The resin may be a mixture or polymer of multiple types of resins.

[0017] The penetration inhibiting layer 12 may have a color derived from the resin within a range that does not affect the color of the wood material 11, but it is preferably colorless transparent or a color close thereto. This is for maintaining the color derived from the wood material 11. However, in order to cancel out a slight color change caused by the penetration inhibiting layer 12 and the surface coating film layer 13, coloring pigments or the like may be contained as necessary, but it is preferable that the penetration inhibiting layer 12 basically does not contain coloring components such as coloring pigments. This is because if the coating is chipped or damaged, a difference in light and shade may occur.

[0018] It is preferable to select a paint (such as the type and formulation of the resin) for the penetration inhibiting layer 12 that has excellent adhesion to both the wood material 11 and the surface coating film layer 13. The penetration inhibiting layer 12 preferably contains an ultraviolet absorber (UVA, HALS, etc.). This is because discoloration caused by ultraviolet rays during the manufacturing process and product use can be suppressed thereby.

[0019] Although it is also conceivable to use an ultraviolet absorber for the surface coating film layer 13, using an ultraviolet curable paint for forming the surface coating film layer 13 becomes difficult, and the degree of freedom in selecting the manufacturing process is narrowed. By including an ultraviolet absorber (UVA, HALS, etc.) in the penetration inhibiting layer 12, it becomes possible to use an ultraviolet curable paint for forming the surface coating film layer 13.

[0020] (Surface coating film layer 13) The surface coating film layer 13 is a layer formed to provide surface performance according to each application, such as abrasion resistance and stain resistance. Due to the surface coating film layer 13, scratches and discoloration are less likely to occur even after long-term use, and the natural and beautiful appearance of the wood can be maintained.

[0021] Examples of the resin constituting the surface coating film layer 13 include urethane resins, acrylic resins, acrylic urethane resins, etc. The resin may be a blend or polymerization of multiple types of resins. Examples of the paint for forming the surface coating film layer 13 include solvent-free paints such as ultraviolet curable types, water-based resin paints, solvent-based paints, etc., and the type of solvent is not limited.

[0022] The surface coating layer 13 preferably has a low brightness. This results in a finish similar to that of natural wood, enabling a more natural appearance as if it were not painted at all. When a slight color change occurs due to the provision of the penetration prevention layer 12 and the surface coating layer 13, the surface coating layer 13 may contain a coloring pigment or the like as necessary.

[0023] The painted wood material 10 is suitable for use in building materials such as floors, walls, ceilings, and stairs, and furniture such as tables, chairs, and shelves.

[0024] [Color tone of the painted wood material 10] The painted wood material 10 includes a penetration prevention layer 12 formed on the surface of the wood material 11 and a surface coating layer 13 formed on the surface of the penetration prevention layer 12, and has the natural appearance inherent to wood. The natural appearance inherent to wood can be evaluated as follows.

[0025] The difference between the lightness measured on the surface of the surface coating layer 13 and the lightness measured on the surface of the wood material 11 after removing the surface coating layer 13 and the penetration prevention layer 12 is 5.0 or less. That is, the painted wood material 10 is required to have a lightness similar to that of the wood material 11.

[0026] The difference between the hue measured on the surface of the surface coating layer 13 and the hue measured on the surface of the wood material 11 after removing the surface coating layer 13 and the penetration prevention layer 12 is preferably 5.0 or less. That is, the painted wood material 10 preferably has a hue similar to that of the wood material 11.

[0027] The lightness and hue are measured based on JIS Z8781-4 using a CR-410 manufactured by Konica Minolta. Specifically, the measurement is performed by the following method. (1) Measure at six positions avoiding specific locations such as the grain and knots of the sample of the painted wood material 10. (2) Grind the surface until the base of the wood material 11 is exposed. For example, grind to a position 0.2 mm deep from the interface between the wood material 11 and the coating film (surface coating layer 13 and penetration prevention layer 12). (3) The exposed wood material 11 is measured at the same six points as in (1) above. (4) Calculate the difference before and after grinding (before grinding - after grinding), and use the average of the 6 points as the measurement result.

[0028] [Manufacturing method for painted wood material 10] The painted wood material 10 comprises the steps of applying a water-based resin paint to the surface of an unpainted wood material 11, drying it to form a penetration-inhibiting layer 12, and applying a surface resin paint to the surface of the penetration-inhibiting layer 12, drying it to form a surface coating layer 13. Since the water-based resin paint has the property of being less likely to penetrate the wood material 11 compared to solvent-based paints, it can suppress discoloration of the wood, i.e., wet color, caused by the resin penetrating the wood material 11. Furthermore, since the penetration-inhibiting layer 12 formed by the drying of the water-based resin paint covers the surface of the wood material 11, it can suppress the penetration of the surface resin paint applied thereafter into the wood material 11. As a result, the surface coating layer 13 becomes less likely to penetrate the wood material 11, and the resulting painted wood material 10 has suppressed wet color and possesses the natural appearance of the wood.

[0029] It is preferable that the unpainted wood material 11 has been smoothed beforehand using a sander or the like.

[0030] The water-based resin paint preferably has film-forming properties. The resulting penetration-inhibiting layer 12 covers the surface of the wood material 11, making it easier to prevent the surface resin paint applied afterward from penetrating the wood material 11. Furthermore, the water-based resin paint may be selected for its components that do not easily penetrate the paint used to form the surface coating layer 13. In addition, there are no restrictions on the number of times the water-based resin paint can be applied, and it may be applied multiple times. This should be determined according to the type of wood material 11 and the properties of the surface coating layer 13.

[0031] The surface resin coating should be one that adheres well to the penetration-inhibiting layer 12 and, depending on the type of resin in the penetration-inhibiting layer 12, is also designed to resist penetration. There are no restrictions on the number of times the surface resin coating can be applied; it may be applied multiple times. This can be determined according to the type of wood material 11 and the properties of the penetration-inhibiting layer 12. [Examples]

[0032] A base material made of 10.0 mm thick plywood was prepared as an unpainted wood material, with a 2.0 mm thick sawn veneer applied to the surface. The sawn veneer was made from three types of wood: maple, oak, and walnut.

[0033] (Examples 1-10) In Examples 1-9, approximately 50 g / m² of acrylic urethane-based water-based resin paint was applied to the surface of the wood material that had been smoothed with a sander. 2 The material was applied and dried to form a penetration-inhibiting layer. An acrylic urethane-based UV-curing paint was applied to the surface of the penetration-inhibiting layer, and the process of curing it by irradiating it with ultraviolet light was repeated four times to form a surface coating layer, and painted wood material was prepared as a sample.

[0034] In Example 10, painted wood material was used as a sample, prepared in the same manner as in Examples 4 and 5, except that a 0.3 mm veneer (wood species: oak) was used as the surface decorative material.

[0035] (Comparative Examples 1-10) In Comparative Examples 1 to 9, a surface coating layer was formed by applying an acrylic urethane-based UV-curing paint to the surface of wood material that had been smoothed with a sander, and then curing it by irradiating it with ultraviolet light, repeating this process four times to prepare painted wood material, which was then used as a sample.

[0036] In Comparative Example 10, wood material (maple wood for the sawn lumber) that had been smoothed with a sander was used as a sample.

[0037] The following evaluation tests were performed on the obtained samples.

[0038] (Evaluation of color tone) The measurements were taken using a Konica Minolta CR-410, in accordance with JIS Z8781-4, using the method described below. (1) Measurements were taken at six points on the sample, avoiding specific areas such as wood grain and knots. (2) The sawn slab was ground down to a depth of 0.2 mm from the interface between the sawn slab and the coating using a sander, exposing the raw material of the sawn slab. (3) Measurements were taken of the exposed sawn slab at the same six points as in (1) above. (4) The difference before and after grinding (before grinding - after grinding) was calculated, and the average of the 6 points was used as the measurement result.

[0039] (Evaluation of wet color) The unpainted and painted materials were evaluated by visual inspection. ◎ was used to indicate that there was no wet color (very close to the unpainted color), ○ to indicate that there was almost no wet color (close to the unpainted color, but a noticeable difference in color upon comparison), and × to indicate that there was a wet color (different from the unpainted color).

[0040] (Evaluation of stain resistance) A contamination test (blue ink, black marker, red crayon) was performed on the plywood according to the Japanese Agricultural Standards (JAS). A circle (○) was used if no color remained on the surface of the test piece, and a cross (×) was used if color remained on the surface.

[0041] The sample conditions and evaluation results are shown in Table 1. Color tone was not evaluated in Example 10 and Comparative Example 10.

[0042] [Table 1]

[0043] As shown in Table 1, in all three wood species—maple, oak, and walnut—Examples 1-9 showed small differences in brightness and hue, and also performed well in evaluating wet color and stain resistance. As shown in Example 10, wet color was more pronounced than with sawn lumber, but the effects of the present invention could still be confirmed with veneer. In Comparative Examples 1-9, the hue difference was large and wet color was present in all cases. In Comparative Example 10, although the appearance was good in the unpainted state, the stain resistance was deteriorated. [Industrial applicability]

[0044] According to the present invention, painted wood material can be obtained that has the natural appearance of wood. Painted wood material is useful for use in building materials such as floors, walls, ceilings, and stairs, as well as furniture such as tables, chairs, and shelves. [Explanation of Symbols]

[0045] 10 Painted wood 11 Wood materials 12. Infiltration-inhibiting layer 13 Surface coating layer

Claims

1. The process involves applying a water-based resin paint to the surface of unpainted wood material, drying it, and forming a penetration-inhibiting layer. The process includes applying a surface resin coating to the surface of the penetration-inhibiting layer and drying it to form a surface coating layer. A method for manufacturing painted wood products.

2. The aforementioned water-based resin coating has film-forming properties. A method for producing painted wood material according to claim 1.

3. The aforementioned water-based resin paint does not contain coloring pigments. A method for producing painted wood material according to claim 1.

4. The method for producing wood material is such that the difference between the brightness measured on the surface of the surface coating layer and the brightness measured on the surface of the wood material after the surface coating layer and the penetration-inhibiting layer have been removed is 5.0 or less. A method for producing painted wood material according to claim 1.

5. The method for producing wood-based lumber is such that the difference between the hue measured on the surface of the surface coating layer and the hue measured on the surface of the wood-based lumber after removing the surface coating layer and the penetration-inhibiting layer is 5.0 or less. A method for manufacturing painted wood material according to claim 1.

6. A penetration-inhibiting layer formed on the surface of the wood material, A painted wood material comprising a surface coating layer formed on the surface of the aforementioned penetration-inhibiting layer, The difference between the brightness measured on the surface of the aforementioned surface coating layer and the brightness measured on the surface of the wood material after the aforementioned surface coating layer and the aforementioned penetration-inhibiting layer have been removed is 5.0 or less. Painted wood material.

7. A penetration-inhibiting layer formed on the surface of the wood material, A painted wood material comprising a surface coating layer formed on the surface of the aforementioned penetration-inhibiting layer, The difference between the hue measured on the surface of the aforementioned surface coating layer and the hue measured on the surface of the wood material after the aforementioned surface coating layer and the aforementioned penetration-inhibiting layer have been removed is 5.0 or less. Painted wood material.

8. The aforementioned penetration-inhibiting layer is composed of a film that inhibits the penetration of the surface coating layer into the wood material. Painted wood material according to claim 6 or 7.

9. The aforementioned penetration-inhibiting layer does not contain coloring pigments. Painted wood material according to claim 6 or 7.

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