HK1117556A1

HK1117556A1 - Composition for forming woody coating layers and woody parts

Info

Publication number: HK1117556A1
Application number: HK08108444.7A
Authority: HK
Inventors: Shinji Oogoe; Hidetoshi Omura; Yoshiomi Horiguchi
Original assignee: Sekisui Jushi Kabushiki Kaisha
Priority date: 2005-03-25
Filing date: 2006-03-22
Publication date: 2009-01-16
Also published as: KR101182622B1; CN101146860A; WO2006103992A1; KR20080002771A; CN101146860B; JPWO2006103992A1; JP5209961B2

Abstract

A composition for forming a woody coating layer, capable of forming a layer which hardly peels off even after long-term use; and woody parts whose woody coating layers hardly peel off substrates even after long-term use. Use of an a-olefin/unsaturated carboxylic acid copolymer as the base resin (11) brings about high adhesiveness to a substrate, while the blending of wood meal (12) gives woodiness to the surface of the coating layer (1). Further, the coating layer (1) easily causes cohesive failure in the application by virtue of the incompatibility of the wood meal (12) with the base resin (11), resulting in a layer which hardly peels off even after long-term use.

Description

Composition for forming woody coating layer and woody molded article

Technical Field

The present invention relates to a composition capable of forming a coating layer having a woody texture on an outer surface thereof, and a woody (wood) molded article having a woody texture on an outer surface thereof.

Background

Various kinds of products have been disclosed, including a composition having a woody texture on the outer surface thereof by coating or painting by thermoforming, and a molded article having a woody texture, the molded article comprises a surface layer constituting the outer surface of the molded article and an inner layer forming the inner part of the surface layer, wherein the inner layer comprises an inner resin layer formed by extruding and molding a resin having at least a similar quality from the physical properties of natural wood, the surface layer is prepared by grinding pulverized powder obtained by pulverizing a cellulose material to obtain particles having an increased bulk specific gravity, a layer formed by fixing surface particles, which are smaller in particle size and harder than the powder particles, to the outer peripheral surface of the powder particles to form fixed particles, and mixing a resin and a pigment into the fixed particles, melting the mixture, and molding the mixture; is formed by being fixed to the outside of the inner resin layer (for example, patent document 1).

Further, as a product obtained by coating, a coating material in which silica gel and/or wood powder is mixed in a coating material, and a building panel coated with the coating material are disclosed (for example, patent document 2).

Patent document 1: japanese unexamined patent publication Hei 8-207111

Patent document 2: japanese laid-open patent application No. 2003-128999

Disclosure of Invention

However, in the conventional wood-based molded articles described in patent documents 1 and 2, if a part of the coating layer is scratched or the like during long-term use, peeling proceeds rapidly from the scratched part, and the coating layer may peel off from the object to be coated after long-term use.

The present invention has been made in view of the above-described problems, and provides a composition for forming a woody coating layer that can provide a coating layer that is difficult to peel off even after long-term use, and a woody molded article that is difficult to peel off the coating layer from an object to be coated even after long-term use.

In order to achieve the above object, the present invention has the following configuration. That is, the composition for forming a woody coating layer of the present invention is characterized in that wood powder is blended with a base resin formed using a copolymer of an α -olefin and an unsaturated carboxylic acid.

According to the composition for forming a woody coating layer of the present invention, a high adhesiveness to a coated object can be obtained by using a copolymer of an α -olefin and an unsaturated carboxylic acid in a base resin, and a coating layer surface formed by blending wood powder has a woody texture and is likely to cause cohesive failure in the coating layer when the coating layer is formed because wood powder and the base resin are incompatible with each other, thereby obtaining a coating layer which is difficult to peel off even after long-term use.

Further, in the composition for forming a wood-based coating layer according to claim 1, if the base resin is a powder and wood flour is blended in the powder, it is preferable because the work of processing wood flour can be reduced and wood flour is blended in the base resin and the composition has fluidity and is easily applied to the outer surface of a coating object having various shapes.

Further, the woody molded article of the present invention is a molded article having a coating layer provided on a substrate and having a woody surface by the coating layer, wherein the coating layer is formed using the composition for forming a woody coating layer according to any one of claims 1 to 3.

According to the wood-based molded article of the present invention, high adhesion to a coated object can be obtained by using the base resin, and the surface of the coating layer has a woody texture by blending the wood powder, and since the wood powder and the base resin are incompatible with each other, aggregation destruction in the coating layer is easily caused, and the coating layer is hardly peeled from the coated object even after long-term use.

In the wood-based molded article according to claim 4, it is preferable that the coating layer is formed by thermoforming the wood-based coating layer forming composition, since the coating layer can be easily provided on a substrate having various shapes, and the adhesiveness of the base resin can be easily exhibited.

Further, in the wood-based molded article according to claim 4 or 5, if the surface of the coating layer is sanded, the visual effect can be improved, and the exposed area of the wood powder is increased, the tactile effect can be improved, and the wood texture can be further improved, which is preferable.

According to the composition for forming a woody coating layer of the present invention, a high adhesiveness to a coated object can be obtained by using a copolymer of an α -olefin and an unsaturated carboxylic acid in a base resin, and a coating layer surface formed by blending wood powder has a woody texture and is likely to cause cohesive failure in the coating layer when the coating layer is formed because wood powder and the base resin are incompatible, and thus a coating layer which is difficult to peel off even after long-term use can be obtained.

Further, according to the woody molded article of the present invention, high adhesiveness to the object to be coated can be obtained by the base resin, and the surface of the coating layer has a woody texture by blending the wood powder, and since the wood powder and the base resin are incompatible with each other, aggregation destruction in the coating layer is easily caused, and the coating layer is hardly peeled from the object to be coated even after long-term use.

Drawings

FIG. 1 is an explanatory view showing one embodiment of the woody molded body of the present invention.

FIG. 2 is an explanatory view showing an example of a method of applying the composition for forming a wood-based coating layer of the present invention to thermoforming.

FIG. 3 is an explanatory view showing another embodiment of the woody molded body of the present invention.

Fig. 4 is a longitudinal sectional view showing details of a corner portion of the wood-based molded article shown in fig. 3.

FIG. 5 is a perspective view showing still another embodiment of the woody molded body of the present invention.

FIG. 6 is a perspective view showing an example of a product using the woody molded article of the present invention.

Description of the symbols

1 coating layer

11 base resin

12 Wood flour

2 base material

10 Wood-based molded article

Composition for forming coating layer of wood A

Detailed Description

The following detailed description of the preferred embodiments of the present invention is based on the accompanying drawings.

FIG. 1 is a view showing a first embodiment of the woody molded article of the present invention, wherein (a) is a perspective view showing the whole and (b) is a sectional view showing the coating layer in detail. First, in (a), the covering (deck) material 10 is formed by providing the covering layer 1 over the entire circumferential surface of the base material 2, and the cross section β is 138mm in the lateral direction and 45mm in the thickness direction γ. The base material 2 is formed of an integral aluminum extrusion, and with respect to its cross section, the hollow portion 21 is made to cross in the thickness direction γ, and 1 rib (rib)22 is provided midway in the transverse direction β, and such a cross section is provided continuously in the longitudinal direction α, whereby one rib 22 is provided in the longitudinal direction α in a cross-sectional rectangle, thereby forming the base material 2 in a square tube shape in which the hollow portion 21 is divided into 2 parts. By providing the ribs 22 in the hollow portions 21 of the base material 2, the second moment of area can be increased, and by using an aluminum extrudate, the base material 2 having the same cross section in the longitudinal direction α can be easily obtained. The base material 2 is provided with a projection 23 on the lower inner surface thereof, so that the cover material 10 can be firmly screwed when it is mounted on the support beam material.

The coating layer 1 is formed directly on the outer surface of the substrate 2 formed of the aluminum extrudate by extrusion coating molding. In (b), 80-mesh wood flour 12 obtained by pulverizing western hemlock fir (Tsuga hephyllla) is substantially uniformly dispersed in a base resin 11 which is an ethylene-acrylic acid copolymer, and the surface of the coating layer 1 is formed into a rough surface by sanding (sanding). Since the base resin 11 is an ethylene-acrylic acid copolymer, high adhesion to the aluminum substrate 2 can be obtained. Further, since base resin 11 and wood powder 12 are not compatible with each other although they are bonded to each other, when an external force is applied to coating layer 1, stress is not concentrated on the interface between coating layer 1 and substrate 2, and is dispersed at the interface between base resin 11 and wood powder 12, so that even if a scratch such as a scratch reaching substrate 2 is generated in coating layer 1, peeling from the scratch is prevented rapidly, and in the case of an external force such as sand flying or expansion and contraction accompanying a temperature change, peeling and breakage are not generated rapidly at the interface between coating layer 1 and substrate 2, and breakage is possible at the interface between base resin 11 and wood powder 12, so that peeling and breakage of coating layer 1 do not occur rapidly, and the coated state of coating layer 1 can be maintained for a long period of time.

The copolymer of an α -olefin and an unsaturated carboxylic acid used in the base resin 11 can secure a skeleton as a resin by the α -olefin, and can have durability, stability, and the like, and can have adhesiveness to a substrate or wood powder by the unsaturated carboxylic acid. As the α -olefin, an olefin having about 2 to 8 carbon atoms selected from the group consisting of ethylene, propylene, isobutylene, and hexene is preferable. The alpha-olefin component is more preferably ethylene or propylene. The most preferred alpha-olefin component is ethylene.

Examples of the unsaturated carboxylic acid include both monocarboxylic acids and polycarboxylic acids, and derivatives thereof including esters and anhydrides, and acids such as acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, crotonic acid, maleic acid, and fumaric acid which react with an amine functional group to form an amide bond are mentioned. Acid chlorides, amides, and esters, including acryloyl chloride and acrylamide, may also be used. Further, as the esters, there are methyl acrylate, methyl methacrylate, ethyl acrylate and dimethylaminoethyl methacrylate. Mono-esters of dicarboxylic acids such as monomethyl maleate, monomethyl fumarate, monoethyl fumarate and maleic anhydride may also be suitably employed. The proportion of the unsaturated carboxylic acid component may be suitably set in consideration of both the required adhesive force and durability, but is generally preferably from about 1% to about 35%, more preferably from about 2% to about 20%, based on the total number of moles.

When ethylene is used as the α -olefin component, acrylic acid is preferably used as the unsaturated carboxylic acid. That is, the base resin is preferably an ethylene-acrylic acid copolymer.

The ethylene-acrylic acid copolymer resin has excellent adhesion to a substrate such as aluminum, and when the ethylene-acrylic acid copolymer resin is used as a base resin, a composition for forming a wood coating layer having excellent adhesion to aluminum or the like can be obtained even when wood powder is highly filled. Further, since the ethylene-acrylic acid copolymer resin has flexibility and is excellent in adhesion to wood powder, it has an effect of suppressing the occurrence of cracks in the coating layer due to shrinkage in the thickness direction of the coating layer in a wood-based molded article in which the composition for forming a wood-based coating layer is used for the coating layer, and also has an effect of suppressing the occurrence of scratches and the like on the surface.

Further, since the ethylene-acrylic acid copolymer resin has excellent adhesion to wood powder, the wood powder can be prevented from being exposed on the surface of the composition for forming a wood-based coating layer or a wood-based molded article using the composition for forming a wood-based coating layer as a coating layer. That is, by using the ethylene-acrylic acid copolymer resin, the surface of the wood powder is easily coated with the resin, and the composition for forming a wood coating layer itself and the wood molded article can be made excellent in weather resistance, water resistance and chemical resistance, while preventing deterioration of the wood powder.

Further, since the ethylene-acrylic acid copolymer resin has carboxyl groups introduced therein, the ethylene-acrylic acid copolymer resin can have a wet texture due to the action of the carboxyl groups oriented on the surface and moisture bonded to the carboxyl groups, and can provide a tactile sensation similar to that of wood flour when it comes into contact with the surface of a living wood.

In such a point that the ethylene-acrylic acid copolymer resin has excellent adhesiveness to aluminum and wood powder, the content of acrylic acid in the ethylene-acrylic acid copolymer resin is preferably 5 to 10% by weight, and more preferably 6 to 9% by weight.

The acrylic acid content in the ethylene-acrylic acid copolymer resin can be determined by an IR method, for example, by measuring the acrylic acid content with a known sample by FT-IR, measuring the absorbance attributed to the main chain and the absorbance attributed to the acryl group, and preparing a standard line showing the correlation between the acrylic acid content and the absorbance.

When the ethylene-acrylic acid copolymer resin is used for forming a coating layer of a woody molded article, it is preferable that the durometer hardness (Shore D) is 45 to 55, and more preferably 49 to 51, in terms of imparting a suitable texture to the surface and preventing damage. Further, the tensile strength is preferably 20MPa or more and the elongation at break is preferably 500% or more. The Duroc rebound hardness can be measured in accordance with JIS K7115, and the tensile strength and the tensile elongation at break can be measured in accordance with JIS K7113.

When the wood-based coating layer-forming composition is mixed with wood flour, the melt flow rate is preferably 3 to 25g/10 min, more preferably 3 to 7g/10 min, and particularly preferably 4 to 6g/10 min, at the point where extrusion processing on a substrate is possible with appropriate fluidity, while preventing the processing temperature from becoming high during extrusion molding, reducing the risk of modifying the wood flour, etc.

The melting point can be measured using a differential scanning calorimetry analyzer which is generally used, and can be determined, for example, by measuring the peak of the endothermic peak associated with phase transition in a sample of about 5mg at a temperature increase rate of 10 ℃/min under a nitrogen atmosphere.

In addition, the melt flow rate can be measured based on JIS K7210.

As the wood powder 12, a pulverized product obtained by pulverizing an end stalk or waste of a fir, a cypress, a western hemlock, etc., saw dust, etc. can be preferably used, and the particle size thereof is 10 to 500 mesh, but the particle size of wood powder is more preferably about 60 to 100 mesh.

In the composition for forming a wood coating layer, which combines a base resin and wood powder, the wood powder content may be suitably adjusted depending on the adhesion to the object to be coated and the wood texture, but is preferably 10 to 80% by weight, more preferably 20 to 50% by weight.

When the base resin is an ethylene-acrylic acid copolymer resin as described above, the amount of wood flour received is large, and therefore, a larger amount of wood flour can be blended than when a resin such as polyethylene is used as the base resin, and for example, 100 parts by weight or more of wood flour can be blended per 100 parts by weight of the ethylene-acrylic acid copolymer resin.

Thus, a composition for forming a wood-based coating layer containing wood flour in an amount larger than the wood flour content of the coating layer formed on the substrate can be prepared, and the coating layer having a desired wood flour content can be formed by so-called dry blending.

For example, when the coating layer is extruded and laminated on the substrate, pellets of the ethylene-acrylic acid copolymer resin monomer and pellets highly filled with wood powder are mixed by a ribbon blender or the like, and then put into a hopper, melt-mixed in an extruder, and laminated on the substrate. Thus, the composition for forming a woody coating layer does not need to be stored for each woody molded product to be produced, the stock amount of materials can be reduced, and the woody molded product can be produced at a lower cost while being suitable for various products with a small amount.

When wood flour is blended with a base resin, the base resin is blended with the wood flour in a heated and molten state, and kneaded by a mixer, a twin-screw extruder or the like to prepare a granulated raw material, pellets or a powder obtained by further pulverizing the raw material, pellets or the powder, but it is preferable to blend the wood flour after previously preparing the base resin into a powder, and the base resin is pulverized and ground by a single component, so that the particle size can be easily made uniform, and the base resin and the wood flour can be easily formed without kneading. In this case, in order to improve the uniform dispersibility of the wood flour in the base resin, it is preferable that the particle size of the base resin as a powdery material is close to the particle size of the wood flour, and the particle size of the base resin is preferably distributed in a range of about 50 to 200% with respect to the average particle size of the wood flour.

In the composition for forming a woody coating layer, a plasticizer, a stabilizer, a filler, a foaming agent, a foaming aid, an ultraviolet absorber, a pigment, an antistatic agent, and the like may be blended as necessary.

FIG. 2 is an explanatory view of an example of a method of applying the composition for forming a wood-based coating layer of the present invention to thermoforming. First, (a) is a method of extrusion coating molding, in which a metal substrate 2 is drawn by a drawing machine T1, preheated in a preheating furnace Y, and then integrally coated with an extruder E to produce a coating layer 1. Here, the powdery composition a for forming a woody coating layer charged into the hopper H is supplied to the extruder E, and the composition a for forming a woody coating layer is melted in the extruder E, thereby laminating the coating layer 1 on the substrate 2. The wood-based molded article 10 continuously formed in the longitudinal direction by the extruder E is pulled by a tractor T2, trimmed in profile by a shaping machine (sizing) S, cooled and solidified by a cooling bath C, and cut into a predetermined length by a cutter K to obtain a product.

In this case, since the coating layer 1 is formed of the composition for forming a woody coating layer containing wood powder which is not compatible with the resin material in the ethylene-acrylic acid copolymer resin, cohesive failure is easily caused at the cut end face, and interfacial peeling from the substrate 2 can be suppressed.

If interfacial separation occurs at the cut end face or the processed end portion such as the opening end portion obtained by punching or the like, separation in the inward direction is likely to be derived from the separation at the end portion, large separation is likely to occur between the substrate and the coating layer, and water permeation or the like may be caused in some cases, and corrosion of the substrate may also occur. However, in the wood-based molded article as described above, since the interface peeling can be suppressed by the occurrence of cohesive failure at the processed end portion, the wood-based molded article can be provided with long-term durability by suppressing corrosion or the like while maintaining excellent initial appearance of the wood-based molded article for a long period of time.

In the extrusion coating molding, the shape and size of the composition a for forming a woody coating layer are not particularly limited, and if it is coated by the extruder E, the composition a for forming a woody coating layer in the shape of powder, granules, granulated pieces or the like can be suitably used.

Further, the coating layer is preferably such that the shrinkage amount per 1m of the woody molded article is 0.5mm or less at 5 cycles of a heat cycle test of-20 ℃ and 80 ℃ and the coating layer can be peeled off from the interface of the metal smooth substrate, so that the phenomenon that the coating layer shrinks and the substrate is exposed from the end portion can be eliminated even when used under severe conditions of temperature change, and the substrate and the coating layer can be separated at the time of disposal to facilitate recycling.

In the case where a metal material is used as the base material and a composition for forming a woody coating layer based on an ethylene-acrylic acid copolymer resin is extrusion-laminated as the coating layer on the base material, it is preferable that the surface temperature of the metal material to be the base material is preheated to a temperature of-30 to +10 ℃ with respect to the melting point of the ethylene-acrylic acid copolymer resin to be the base of the composition for forming a woody coating layer to perform extrusion lamination, and that the draw-down ratio (draw-down ratio) is preferably about 1.0 as the extrusion condition, in view of the fact that the base material and the coating layer can be separated in this manner and recycling is easy.

(b) In the flow-dipping method, a base material 2, which is a mesh panel formed by welding metal wires in the longitudinal and transverse directions, is suspended from a hanger G, and the base material 2 is preheated. The powdery woody coating layer-forming composition a is filled in the flow tank R, and hot air is blown into the powdery woody coating layer-forming composition a from below, whereby the woody coating layer-forming composition a is kept at a high temperature to some extent and a powdery state is brought into a state close to suspension. By immersing the substrate 2 in the composition a for forming a woody coating layer, the composition a for forming a woody coating layer is adhered to the surface of the substrate 2 substantially uniformly, and by heating and baking the composition a in the adhered state at a temperature at which the base resin is melted and the wood powder is not scorched, the base resin is brought into a molten state and homogenized (leveling), whereby a smooth and uniform coating layer can be obtained on the substrate 2. For example, when an ethylene-acrylic acid copolymer is used as the base resin and wood flour of Sequoia tsugae (T.tsugae; tsugahetetophylla) is blended, the baking temperature is preferably about 200 to 280 ℃.

When the coating layer is formed on the surface of the substrate 2 by the flow immersion, the coating layer is suitably used not only for a mesh panel but also for a substrate having a particularly complicated outer shape such as a jewel of a building, a knob of a door, various metal fittings, and the like. In addition, in the fluid impregnation, the particle sizes of the base resin and the wood powder are preferably made similar as described above, and both the particle sizes of the base resin and the wood powder are preferably 10 to 1000 μm, and preferably about 50 to 500 μm.

FIG. 3 is an explanatory view showing another embodiment of the woody molded body of the present invention. The woody molded body 10A is formed by providing the coating layer 1 over the entire periphery of the substrate 2, and the coating layer 1 is formed by blending 80-mesh wood powder obtained by pulverizing western hemlock into a base resin which is an ethylene-acrylic acid copolymer, and the substrate 2 is formed of an aluminum extrudate, as in the embodiment shown in fig. 1. The woody molded body 10A has a cross section of 100mm in both the left-right direction β and the up-down direction γ, and has a protrusion 23 provided near the middle of the inner surface of the four sides of the cross section of the hollow portion 21 to firmly fix the screw, and screw holes 24 such as a gap for easy attachment are provided on the inner surfaces of the four corners of the cross section.

Fig. 4 is a longitudinal sectional view showing the details of the corner portion of the wood-based molded body 10A. The coating layer 1 was formed directly on a smooth metal substrate 2 and had a thickness of 2 mm. An R groove 25 is formed on the outer surface of the substrate 2, and the shrinkage in the longitudinal direction α can be further suppressed by inserting the coating layer 1 into the R groove 25.

FIG. 5 is a perspective view showing still another embodiment of the woody molded body of the present invention. In the wood-based molded article 10B, the coating layer 1 is directly formed on the outer surface of the base material 2, as in fig. 1 and 3. The cross section of the woody molded body 10B was 60mm in the longitudinal direction and 40mm in the transverse direction.

Fig. 6 is a perspective view showing an example of a product using the wood-based molded articles 10A and 10B. The wood-based molded article 10A is erected from the ground surface to form a pillar, and a plurality of stepped wood-based molded articles 10B are formed as a beam material across the plurality of erected wood-based molded articles 10A as pillars, thereby forming a fence G.

Examples

The present invention will be described in more detail below by way of examples and comparative examples, but the present invention is not limited to these examples.

(example 1)

Pellets of the composition for forming a woody coating layer of example 1 were prepared according to the formulation shown in Table 1.

TABLE 1

Material	Compounding amount (parts by weight)
		Ethylene-acrylic acid copolymer resin	100
Wood flour	30
		Calcium carbonate	16
Pigment (I)	1.5

Further, as the ethylene-acrylic acid copolymer resin, a resin having an acrylic acid content of 7% by weight, a melting point of 98 ℃, a melt flow rate of 5g/10 min, and a durometer hardness (Shore D) of 50 was used.

As the wood flour, a 80-mesh-sieve wood flour obtained by pulverizing and grinding western hemlock fir was used.

In addition, calcium carbonate having an average particle size of about 2.0 μm was used as calcium carbonate.

The composition for forming a woody coating layer of example 1 was extruded on an aluminum substrate at a resin temperature of about 170 ℃ using an extruder, laminated, and cut into 1m to produce a woody molded article.

The woody molded article has good appearance and excellent texture. Further, the adhesion between the substrate and the coating layer is also good. Further, even when a 30-cycle thermal cycle test of-20 ℃x3 hours/80 ℃x3 hours was carried out, peeling and shrinkage of the coating layer, which were practically problematic, were not observed.

It was confirmed that the shrinkage at the end (difference between the end of the substrate and the end of the coating layer) was particularly excellent when the shrinkage was less than 0.5mm, and the surface temperature of the aluminum substrate was preheated to a temperature of-30 to +10 ℃ relative to the melting point of the copolymer resin.

(example 2)

Pellets of the composition for forming a woody coating layer of example 2 were prepared according to the formulation shown in Table 2.

TABLE 2

Material	Compounding amount(parts by weight)
		Ethylene-acrylic acid copolymer resin	25
Wood flour	30
		Calcium carbonate	16
Pigment (I)	1.5

Further, as the wood flour, a 80-mesh-sieved wood flour obtained by pulverizing and grinding western hemlock pine was used.

The composition for forming a woody coating layer of example 2 and the ethylene-acrylic acid copolymer pellets were dry blended at a weight ratio of 1: 1, and the obtained dry blend was extrusion-laminated on an aluminum substrate at a resin temperature of about 170 ℃ using an extruder and cut into 1m to produce a woody molded article.

In the composition for forming a wood-based coating layer of example 2, the wood powder was not separated from the composition for forming a wood-based coating layer, and the wood powder was in a good mixed state.

The resulting woody molded article had good appearance and excellent texture as in the case of using the composition for forming a woody coating layer of example 1. Further, the adhesion between the substrate and the coating layer is also good. Further, even when a 30-cycle thermal cycle test of-20 ℃x3 hours/80 ℃x3 hours was carried out, peeling and shrinkage of the coating layer, which were practically problematic, were not observed.

Comparative example 1

Pellets of the composition for forming a woody coating layer of comparative example 1 were prepared in accordance with the formulation shown in Table 3.

TABLE 3

Material	Compounding amount (parts by weight)
		High density polyethylene	100

Wood flour	30
		Calcium carbonate	16
Pigment (I)	1.5

Further, high density polyethylene having a density of 964kg/m was used³A high-density polyethylene having a melt flow rate of 5g/10 min and a durometer hardness (Shore D) of 73.

As the wood flour, a 80-mesh-sieved wood flour obtained by pulverizing and grinding sequoia cunninghamiana was used.

The resulting woody molded article had good appearance as in the case of using the composition for forming a woody coating layer of examples 1 and 2, but had poor texture as compared with the case of using the composition for forming a woody coating layer of examples 1 and 2. Further, at the cut end, interfacial separation was observed between the substrate and the coating layer.

In addition, a thermal cycle test of-20 ℃ x 3 hours/80 ℃ x 3 hours was performed, and after several cycles, the shrinkage exceeded 1mm, and after 30 cycles, shrinkage of 3 to 5mm was observed.

From the above, it is understood that a coating layer which is difficult to peel off even after long-term use can be obtained by using a composition for forming a wood-based coating layer, which is characterized in that wood powder is blended with a base resin formed from a copolymer of an α -olefin and an unsaturated carboxylic acid.

Claims

1. A wooden molded article having a coating layer on a base material, the coating layer providing a wooden surface to the molded article,

the coating layer is formed directly on the outer surface of the substrate by thermoforming a composition for forming a woody coating layer, which is obtained by blending wood powder with a base resin formed using an ethylene-acrylic acid copolymer.

2. The wood-based molded article according to claim 1, wherein the coating layer enters an R groove formed in an outer surface of the base material.

3. The wood-based molded article according to claim 1 or 2, wherein the surface of the coating layer has been subjected to sanding.