JPH026614B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing colored wood, in which coniferous wood of pine and cypress trees is decolorized by degreasing, or the resin content in the wood is extracted and removed by decolorization after decolorization. At the same time, after uniformly whitening the material color,
A mixed resin liquid of a low-molecular resin liquid consisting of an addition-polymerizable synthetic resin monomer, oligomer, or prepolymer and a thermoplastic synthetic resin polymer is injected into this, and the mixed resin liquid is uniformly dispersed within the wood vacuoles. Next, by polymerizing and curing the resin liquid to form a resin body with a large number of voids mixed inside the softwood material,
This invention relates to a method for producing colored wood, which is characterized by making the wood grain pattern of coniferous wood appear beautiful and clear, and by turning the whole material white or by focusing on an arbitrary color, and also by improving various physical properties of the wood. . Hereinafter, the low-molecular resin consisting of the monomer or oligomer or prepolymer of the addition polymerization type synthetic resin and the polymer of the thermoplastic synthetic resin will be simply referred to as the addition polymerization type synthetic resin liquid and the thermoplastic polymer.

Traditionally, wood, especially softwood wood, has a beautiful grain pattern and has been widely used for furniture and construction materials that take advantage of its decorative properties. If it is to be colored, it must be painted or bleached and then colored with a coloring agent; in the former case, the wood grain pattern tends to become unclear because the surface is covered by the colored paint. The cosmetic properties are lowered, and in the latter case, lignin and other components in the wood are removed during bleaching, resulting in a decrease in strength.

On the other hand, a material made by injecting and curing a synthetic resin liquid into a wood material to improve its strength, hardness, and other physical properties is known as W.P.C (Wood Plastic Composite). As a result of filling wood cells with synthetic resin, the wood material becomes transparent as a whole, and the color of the wood is added to it, resulting in a dark color. The disadvantage was that the transparency of the spring wood part was higher than that of the autumn wood part, and the shading of the wood grain pattern was reversed, resulting in an appearance that was completely different from natural wood and lacked a sense of nature.

On the other hand, the applicant previously proposed a mixed resin solution of an addition-polymerized synthetic resin solution and a thermoplastic polymer as a method to eliminate such W.P.C. wood grain reversal phenomenon and make natural wood grain appear. We have discovered a method of injecting and curing wood materials to form a resin body with a large number of voids inside the wood, and using the voids in the resin body to whiten the wood material and reveal its natural wood grain. (Gan Sho 53-42827).

However, when the above method is applied to softwood materials, although it is possible to give an overall opaque white appearance, uneven whiteness occurs along the wood grain, making the wood grain unclear, and it is difficult to stabilize the cosmetic properties. It was difficult.

In order to eliminate such uneven whiteness along the wood grain, the previous invention added a surfactant to the resin liquid to make the injection uniform. Attempts were made to whiten the color of the wood itself by bleaching it and then inject it with resin to eliminate uneven whiteness. Not only does the tar inside inhibit the injection of the injected resin liquid, but also the presence of different types of resin (such as tar) in the mixed resin liquid inhibits the reaction of the injected resin liquid, slowing down the curing process, and causing the white color. A new problem was that the coloring was not uniform, and it was difficult to achieve a uniform white wood finish on the entire surface by simply whitening the wood color by bleaching or promoting injection with a surfactant. Here, the above-mentioned injection inhibition means that the monomers, oligomers, prepolymers, etc. of addition-polymerized synthetic resins, which are low-molecular resin liquids, are narrowed by resin, and even if the openings of wood vacuoles are small, they are relatively small. In contrast, thermoplastic synthetic resin polymers with relatively large molecular weights are difficult to inject into wood vacuoles if the openings are small. When the injected resin liquid is cured, the addition polymerization type synthetic resin first cures while generating heat, and this heat causes the thermoplastic synthetic resin to expand. When the curing heat generation of the addition polymerization type synthetic resin ends and it is cooled, the thermoplastic synthetic resin contracts, creating voids therein and turning white. Therefore, in areas where injection inhibition due to resin occurs, the amount of thermoplastic synthetic resin with a relatively large molecular weight is small and whitening is difficult to occur, and there is a large difference between the area where there is less resin and injection is sufficient, and the area is sufficiently whitened. This will result in uneven color.

The present invention has been made in view of the above-mentioned drawbacks and problems, and is intended to make the beautiful wood grains of softwood materials such as pine and cypress trees appear clearly and evenly over the entire surface of the wood, which has been whitened. This is a method for producing colored wood, in which the resin content in the wood is removed by degreasing or degreasing and then decolorizing the injected material, such as pine or cypress. By injecting a mixed resin liquid of addition-polymerized synthetic resin liquid and thermoplastic polymer and curing it, a resin body with a large number of voids evenly mixed in the wood is formed, resulting in poor curing and injection inhibition. To provide a method for producing colored wood, which is characterized by eliminating unevenness in whiteness due to oxidation, making the wood grain pattern unique to softwood wood clearly appear in its original form, and improving the physical properties of the wood.

In the present invention, degreasing treatment refers to immersing softwood in an alkaline solution such as sodium hydroxide, sodium carbonate, sodium bicarbonate, or sodium phosphate, or in a solvent such as alcohol, benzene, ethylene glycol, or toluene, or in boiling water. The resin content is removed by steaming softwood wood under appropriate steam pressure in a pressure cooker, and the resin extraction time and size vary depending on the species and size of the softwood wood used. The type and concentration of the solvent are appropriately determined and carried out to the extent that no significant decrease in strength or discoloration occurs.

For example, when immersing in an alkaline solution,
Concentration is 1-3%, treatment temperature 20-50℃, treatment time 30
minutes to 120 minutes is appropriate.

In the case of steaming, a steam pressure of 1 to 3 atm and a steaming time of 5 to 60 minutes are appropriate. Also, a surfactant can be added to shorten the processing time.

If the resin content in the wood is removed by degreasing softwood wood in this way, when the mixed resin liquid is injected later, the residual resin content in the wood may inhibit the injection and inhibit the curing reaction during curing. This eliminates the occurrence of uneven whiteness after curing, and allows a whitened resin body to be uniformly formed inside coniferous materials with a high resin content, such as pine and cypress trees.

Further, decolorization is achieved by removing the resin content, but when degreasing that causes discoloration of the wood, the degreased softwood is further decolorized with a bleaching agent. That is, the resin content is removed without darkening the color of the wood by degreasing treatment that also serves as decolorization or decolorization treatment after degreasing treatment.

Next, when performing the above degreasing treatment, the chemical solution may remain inside the softwood material, so the pH is adjusted to neutralize it, and after sufficient drying, the addition polymerization type synthetic resin solution and thermoplastic polymer are combined. A mixed resin solution consisting of is injected into the softwood material.

The reason why an addition polymerization type synthetic resin liquid is used in the present invention is that when an addition polymerization type synthetic resin is injected into wood and hardened, compared to a condensation type synthetic resin, the cured resin shrinks less, so cracks and deformation are less likely to occur. This is because there is little danger, and since no condensation water is produced, it is possible to cure at low pressure, and various physical properties such as hardness, abrasion resistance, water absorption, etc. can be improved even with low pressure curing.

This addition polymerization type synthetic resin liquid can be roughly classified into thermosetting and thermoplastic depending on the properties after curing, and one of these resins or a mixture of both can be used.

For example, when making a thermoplastic resin body, monomers having one vinyl group per molecule are used, such as olefinic hydrocarbons, acrylic acid monomers, vinyl acetate, vinyl alcohol monomers, halogenated olefinic hydrocarbons, and nitrogen-containing monomers. vinyl monomer,
sulfur-containing vinyl monomer or a mixture thereof,
Monomers with conjugated double bonds such as butadiene,
Alternatively, there are mixtures of these and monomers having one vinyl group per molecule, thermoplastic polyurethane resin liquids, and when making thermoplastic resin bodies, divinylbenzene, diallyl phthalate, etc. have two or more vinyl groups per molecule. A monomer having a vinyl group or these monomers or an unsaturated alkyd resin liquid and 1
A liquid mixture of monomers having one vinyl group in the molecule, a thermoplastic polyurethane resin liquid, and an epoxy resin liquid are used. In addition, the forms of these resins are prepolymers, monomers, oligomers,
Or it may be a mixture of these.

On the other hand, in the present invention, a thermoplastic polymer is used as the resin to be mixed with the above-mentioned addition polymerization type synthetic resin liquid, but this polymer is easy to dissolve and swell, and is compatible with the monomers of the addition polymerization type synthetic resin. Since the oligomer is made into fine particles in the resin solution, it is injected into the voids of the wood cell structure together with the above monomer, and the removal of the resin content in the wood vacuoles inhibits the penetration of the polymer of thermoplastic synthetic resin with a large molecular weight. It is injected into the wood in a uniformly dispersed state without being mixed.

Thermoplastic polymers used include hydrocarbon resins such as polyethylene, polypropylene, and polystyrene; vinyl resins such as polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, and polyvinyl ether; and acrylic resins such as polyacrylate. Examples include nitrogen-containing resins such as polyamide, thermoplastic polyesters, and polyurethane resins.

This thermoplastic polymer is added to the addition polymerization type synthetic resin liquid in a weight ratio of 1 to 98%, preferably 1 to 30%. This is due to economic efficiency, workability due to viscosity, etc.
This is because it is possible to obtain a material that is sufficiently durable for practical use in terms of water absorption and other physical properties of the colored wood, as well as the degree of whitening.

Further, in the present invention, some of various additives may be added to the mixed resin liquid of the thermoplastic polymer and addition polymerization type synthetic resin liquid.

The additives used are listed below.

Organic peroxides, inorganic peroxides, azo compounds, alkali metals, Friedel-Crafts catalysts and other curing agents.

Cobalt-based, manganese-based, tertiary amine-based, organometallic compounds, vanadium, mercaptan, binacon derivatives and other reaction accelerators.

Quinones, hydroquinones, hydrazine salts, amines, nitro compounds, quaternary ammonium salts, phenols, amidines, oximes and other reaction inhibitors and reaction inhibitors.

Azo, anthraquinone, indigo and thioindigo, fluorescent dyes and other dyes.

Anionic, cationic, amphoteric, and nonionic surfactants.

Plasticizers such as phthalate esters and other ester-based chlorine-containing plastics, epoxies, and polyesters; lubricants such as polyethylene glycol and higher fatty acids.

Phosphate esters and other flame retardants.

Polar or non-polar solvents such as methyl alcohol, ethyl alcohol, acetone, toluene, etc.

These additives may be added to the mixed resin liquid of addition polymerization type synthetic resin liquid and thermoplastic polymer,
Alternatively, a mixed resin liquid may be obtained after adding the resin to either one.

Additionally, addition-polymerized synthetic resins and thermoplastic polymers may or may not produce co-soluble liquid mixtures depending on the combination of their respective resins, but if the cured products are immiscible, Available for use.

Injecting mixed resin liquid into softwood materials is generally done by methods such as vacuum method, pressurization method, vacuum pressure method, etc.
The amount of resin injected is approximately the same as that in the production of normal W/P/C, and the injected mixed resin liquid is then polymerized.

When polymerizing the resin liquid, a method using heating or pressurization, or a method using irradiation with ultraviolet rays, electron beams, gamma rays, etc. can be employed.

The mixed resin liquid polymerized and cured in this way is different from the resin body in ordinary W/P/C,
Even though the wood cells of coniferous wood are filled with resin, they form a heterogeneous resin body with many voids mixed in the resin.
Reflection and diffusion of light rays occur at the resin interface, reducing transparency and turning the entire softwood material white.

The whitening of the above coniferous wood is most noticeable in the spring wood where the resin liquid can be easily injected, and the degree of whitening is small in the autumn wood where the wood cells are dense, and the wood color remains as it is, making the softwood material white. A white wood-like appearance with a wood grain pattern can be obtained.

Also, at this time, since the coniferous wood is degreased and bleached in advance to remove the resin in the wood,
The above mixed resin is uniformly injected into the wood, and voids are uniformly generated by curing, resulting in a remarkable whitening effect, and furthermore, coloring components caused by impurities such as residual resin in the wood are removed. Therefore, there is no occurrence of spots due to tar, the wood grain pattern appears softly and clearly, and it is possible to obtain colored wood with a new appearance that combines the base color of plain wood and the wood grain pattern of coniferous wood.

Incidentally, the softwood material that has been degreased and bleached may be colored in advance prior to injecting and curing the mixed resin liquid.

In this case, if the coniferous wood is pre-colored with a coloring agent, the spring wood will be more likely to be colored, so it will take on a dark color, and the autumn wood will have a lower degree of coloring and will take on a lighter color. When the resin liquid is injected and hardened, the spring wood part becomes lighter in color because the resin liquid is more easily injected than the autumn wood part, whereas the autumn wood part has a thicker and denser cell membrane, so the degree of whitening caused by the injected resin is lower. Even if the coloring is low and slight, the colored heather stands out and appears in the white background, and it is possible to obtain a plain wood-like colored wood having a wood grain pattern rich in color variations.

Alternatively, a method of injecting a resin liquid in which a colorant is added to the mixed resin liquid can also be adopted. In this case, unlike the case of W/P/C, the mixed resin liquid forms a heterogeneous resin body in the wood through polymerization and hardening, resulting in a whitened and opaque resin body, so a small amount of A sufficient coloring effect can be obtained even with a coloring agent, and the autumn wood part with a small amount of resin injected shows the color of degreased and bleached wood, making it possible to obtain colored wood with a light grain pattern.

As described above, in the method of the present invention, the resin content in the wood is extracted and removed by decolorizing pine and cypress coniferous wood by degreasing or decolorizing after degreasing, so the color tone of the wood itself becomes white wood-like. The appearance of plain wood can be achieved by treating the wood not only with a simple degreasing treatment but also with bleaching. On the other hand, when decolorizing the wood by bleaching and then degreasing it, areas with a high resin content in the wood are difficult to bleach, causing unevenness and making it impossible to achieve a uniform white wood tone.

Furthermore, in general degreasing, the wood is treated at high temperature in an organic solvent to extract and remove the resin content, which causes the wood to turn dark in color. In this way, wood that has been discolored by degreasing cannot be made into a plain wood color no matter how much whitening resin composition is injected. WPC with toned makeup can be obtained. In addition, the degreasing treatment greatly expands the openings of wood vacuoles that had been narrowed by resin, resulting in the production of low molecular weight polymerizable synthetic resin monomers or oligomers.
Not only the prepolymer but also the thermoplastic synthetic resin polymer with a relatively large molecular weight is injected uniformly over the entire surface of the wood, and by polymerizing and curing this mixed resin liquid, the coniferous wood is decolored and uniformly whitened. This creates a resin body with a large number of voids inside the wood, giving the entire wood a uniform white wood look. This also prevents resin components such as tar from appearing as spots that do not turn white, making it possible to faithfully reproduce beautiful wood grain patterns.

Furthermore, components that inhibit curing of the mixed resin liquid, such as tar in softwood materials containing a large amount of resin, are removed, so there is no reduction in whitening due to poor curing around the wood grain due to the autumn wood area, and the wood grain is clearer. By uniformly whitening the entire wood without damaging the grain of beautiful natural wood such as pine and cypress, it eliminates transparency and produces a white wood-like colored wood that takes advantage of the grain pattern of coniferous wood. be able to.

As mentioned above, in the first step, the coniferous wood of pine and cypress trees is decolorized by degreasing or decolorized after degreasing to extract and remove the resin content in the wood, and the color of the wood is uniformly whitened. A mixed resin liquid consisting of a low-molecular resin liquid consisting of monomers, oligomers, and prepolymers of addition-polymerized synthetic resins and a thermoplastic synthetic resin polymer is injected into this, and the mixed resin liquid is uniformly dispersed within the wood vacuoles. Then, by polymerizing and curing the resin liquid to form a resin body with a large number of voids mixed inside the softwood material, the entire wood is uniformly whitened and a white wood-like finish that takes advantage of the grain pattern of the softwood material is created. Colored wood is obtained.

In addition, since the present invention forms a heterogeneous resin body in wood cells by injecting and curing the mixed resin liquid into the wood material, its appearance is different from that of conventional W.P.C. By selecting a thermoplastic monomer or oligomer as the addition polymerization type synthetic resin, it becomes easier to inject the resin into wood materials and molding becomes easier. When thermosetting resin is used, wood with various physical properties such as heat resistance, chemical resistance, water resistance, strength, abrasion resistance, hardness, and dimensional stability is superior to thermoplastic resin. In addition, the inclusion of thermoplastic polymer suppresses the shrinkage of the injected resin during curing, making it less prone to cracking, warping, twisting, etc. compared to conventional W/P/C. A product with extremely low generation can be obtained.

Furthermore, according to the present invention, the synthetic resin-infused wood material thus obtained can be easily adhered to the surface of an appropriate base material at the same time as the injected resin liquid is cured.

Normal W/P/C shrinks when the resin liquid hardens, so if it is bonded to the base material at the same time, stress will occur due to the difference in shrinkage rate between the wood material, the resin, and the base material, resulting in cracks, warping, twisting, etc. However, in the synthetic resin-infused wood material of the present invention, the resin forms a heterogeneous system as it hardens, and the interface of the resin is partially discontinuous, so deformation occurs easily. It is capable of absorbing stress, thereby minimizing the occurrence of cracks, warping, twisting, etc., and can be bonded to the substrate at the same time as the injected resin liquid is cured.

In this case, an adhesive is generally not necessary because the adhesive properties of the resin liquid attached to the surface of the wood material can be used, but it is of course possible to use an adhesive in combination if a greater adhesive force is required. be.

Next, examples of the present invention and comparative examples will be shown.

Example 1 A sliced veneer of Japanese pine with a thickness of 1 mm was treated with a 2% concentration.
After immersing in a _NaCO3 aqueous solution at a temperature of 30 to 40°C for 1 hour, washing with water, and further immersing in a 2% concentration (COOH) ₂ aqueous solution at a temperature of approximately 30°C for 1 hour. This was thoroughly washed with water and then dried to remove the resin content in the veneer.

Next, a mixed resin solution of 100 parts of unsaturated polyester (alkyd:styrene = 60:40), 5 parts of styrene monomer, 1 part of BPO, and 20 parts of vinyl acetate polymer was injected into the veneer for 2 hours under a reduced pressure of 10 mmHg.
The mixed resin liquid was cured by heating and pressing in a hot press at 10 kg/cm ² at 130° C. for 30 minutes.

The resin injection rate of the thus obtained colored wood was 90%.

Resin injection rate A-B/A×100 A: Weight of veneer after resin injection and curing B: Before resin injection and curing In addition, the appearance of the above-mentioned colored wood is an opaque white color as a whole. It had a white wood-like appearance, with the grain pattern of Japanese pine clearly appearing in the pale cream on the base.

Comparative Example 1 Using the same veneer as in Example 1, a mixed resin liquid was injected and cured under the same conditions without decoloring.

The thus obtained veneer had a resin injection rate of 20 to 30%, and the generation of voids in the resin body was uneven, and the degree of whitening was uneven.Also, the resin had a brownish color in the autumn part where there was a lot of resin. It appeared as spots, and in some places, the resin had flowed out and the wood grain pattern was partially blurred.

In addition, since the autumnal part where the amount of resin injected was small was hardly whitened, the autumnal part appeared dark on the white background, and the difference in shading from the base gave an extremely unnatural feeling.

Example 2 A sliced veneer of Japanese pine with a thickness of 1 mm was treated with a concentration of 1%.
After being immersed in a NaOH aqueous solution for 20 minutes at 30°C, it was washed with water, and then immersed in a 2.4% NaCl solution for 1 hour at a temperature of 20°C.
% concentration of (COOH) ₂ in an aqueous solution under conditions of 30 °C.
The material was soaked for a period of time to neutralize it, and then thoroughly dried to perform degreasing and bleaching at the same time.

Next, 100 parts of unsaturated polyester (alkyd:styrene = 60:40), 5 parts of styrene monomer, 1 part of BPO, 20 parts of vinyl acetate polymer,
A colored mixed resin liquid containing 0.03 parts of oil dye Brown was injected for 2 hours under a reduced pressure of 10 mmHg, then placed on a plywood coated with adhesive and hot pressed at 10 kg/cm ² at 130°C. The mixed resin liquid was cured by heating and pressing for 30 minutes.

The resin injection rate of the colored wood thus obtained was 90%.
The overall color was uniformly light brown with a hint of pink, and the autumn-grained parts had a clear wood grain pattern with pale yellow, giving it the appearance of white wood that expressed the taste of the pine material.

In addition, even if the colored wood obtained in Example 1 is a veneer made of the same resin, there may be differences in the original color tone of the wood in the heartwood and sapwood parts. By performing processing, it is possible to eliminate such differences in color tone.
Furthermore, the color tone of colored wood can be controlled by using a coloring agent such as an oil-based dye, and it is possible to obtain a product having uniform cosmetic properties with less color width.

Claims (1)

[Scope of Claims] 1. After decolorizing coniferous wood of pine and cypress wood by degreasing or decolorizing after degreasing to extract and remove the resin content in the wood and uniformly whiten the wood color,
A mixed resin liquid consisting of a low-molecular resin liquid consisting of a monomer, an oligomer, or a prepolymer of an addition-polymerized synthetic resin and a thermoplastic synthetic resin polymer is injected into this, and the mixed resin liquid is uniformly dispersed within the wood vacuoles. A method for producing colored wood, which comprises then polymerizing and curing the resin liquid to form a resin body in which a large number of voids are mixed inside the softwood material. 2. The method for producing colored wood according to claim 1, which comprises bleaching and degreasing the coniferous wood and then coloring it with an appropriate coloring agent. 3. The method for producing colored wood according to claim 1 or 2, wherein the mixed resin liquid is colored with an appropriate colorant.