JPH01226302A - Preparation of lamellar material having improved wooden surface layer - Google Patents

Abstract

PURPOSE:To give transparency and luster and to improve abrasion resistance and crack resistance, by placing a wooden material impregnated with a specified treating liq. on a surface of a base sheet, heating and pressing it as it is under a wet condition and thereby monolithically molding it with the base sheet. CONSTITUTION:A wooden material is impregnated with a treating liq. prepd. by mixing water or an alcohol with a polybasic acid and a polyhydric alcohol. The said wooden material is placed on an appropriate base sheet and heated and pressed to mold it monolithically with the base sheet. By performing press ing and densifying of the wooden material impregnated with the treating liq. like this, esterification reaction of active groups such as hydroxyl groups in the wood component with an acid anhydride polybasic acid and at the same time, crosslinking of the acid anhydride of the polybasic acid with a polyhydric alcohol are carried out to form a thermosetting resin into which the wood component is chemically bonded, which is cured under the condition that this thermosetting substance infiltrates into gaps of the wood to form a dense layer having a depth and a luster of improved transparency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing modified wood that can chemically modify wood and simultaneously consolidate it to impart novel and rich cosmetic properties to the wood. It is something.

[Conventional technology]

Traditionally, the methods for densifying the natural grain of wood are:
The method used is to impregnate wood with water to swell the entire wood, then pressurize it, dry it, and solidify it.

However, this method simply physically compresses and deforms the wood that has swollen due to moisture and fixes it, so it will return to its original shape once it absorbs moisture, resulting in poor shape stability and a dense wood grain. Since it is only a cosmetic, there is no change in transparency, gloss, etc., and the cosmetic properties are poor.

For this reason, the applicants of the present application have developed a method of chemically treating wood, as described in Japanese Patent Publication No. 62-47686.

In this method, a thin wood board is treated with a reactant that can react with the hydroxyl groups in the wood components to amorphize the wood components, and then heat-pressed to improve transparency, abrasion resistance, and crack resistance. This process transforms the wood into thin sheets of wood.

[Problem to be solved by the invention]

However, according to this method, a step of amorphizing the cellulose by using a reactant such as an esterifying agent or an etherifying agent that can react with the hydroxyl groups in the wood components, and a step of chemically treating the wood veneer in this way is necessary. It requires a step of heating and pressurizing the thin wood board, and in particular, it requires a long time for chemical treatment, resulting in poor productivity.Furthermore, it promotes the reaction between reactants such as esterifying agents and wood components. Not only does this require catalysts such as sulfuric acid and perchloric acid, making the process complicated, but when organic acid anhydrides are used as esterifying agents, by-products are produced when the hydroxyl groups of wood components react. There were production problems such as remaining in the wood and requiring washing and drying treatment.

The present invention simultaneously performs chemical modification and compaction treatment on wood to easily plastically deform the wood and integrate it into a base plate, with the aim of imparting transparency and gloss, and improving wear resistance and crack resistance. The aim is to provide a method for producing a plate-like product having a modified wood surface layer.

[Means to solve the problem]

In order to achieve the above object, in the method for producing modified wood of the present invention, wood and bamboo materials are impregnated with a treatment liquid made by mixing a polybasic acid and a polyhydric alcohol with water or alcohol; Before the above-mentioned treatment liquid is cured, the wood material is placed on a suitable base plate, and heated and pressurized to harden the thermosetting substance produced, and the wood material is integrated with the base plate. This is a characteristic feature.

[For production]

Since the treatment liquid is a water or alcohol solvent, it has a high affinity with the hydrophilic wood, easily penetrating into the microscopic voids in the wood, and coming into contact with active groups such as hydroxyl groups in the wood components.

When the wood is heated and pressurized in this state, the polybasic acid in the treatment liquid decomposes into acid anhydride and water, and the acid anhydride undergoes an esterification reaction with the active groups in the wood components, resulting in plasticization and polybasic acid. It crosslinks with alcohol to create a thermosetting substance within the wood, which fixes the wood in a compacted state.

At this time, when the acid anhydride of the polybasic acid undergoes an esterification reaction with the active group in the wood component, the lignin and the like in the wood component are reduced in molecular weight by solvolysis under acidic and high temperature conditions, resulting in fluidity. As a result, the wood grain appears to flow and curve, changing to a new wood grain pattern different from that before heating and pressing, and at the same time, the low-molecular lignin and the thermosetting substance infiltrate into the voids of the wood. It solidifies in a state where it becomes transparent, forms a dense layer with depth and luster, and improves abrasion resistance, crack resistance, and water resistance.

At that time, if the wooden material impregnated with the above treatment liquid is placed on a base plate before the treatment liquid hardens and subjected to heating and pressure treatment for consolidation as described above, a thermosetting substance is generated. It is possible to integrate wooden materials into the base plate by utilizing the adhesive properties of the wood.

In addition, the wood material that has become plasticized by the treatment liquid is much more easily compressed and deformed than the base plate, so when heated and pressurized,
It has the advantage that the surface wood layer can be consolidated and integrated without causing deformation or destruction of the base plate.

[Example] To describe the example of the present invention in detail, the process includes a step of impregnating a wood material with a treatment solution made by mixing a polybasic acid and a polyhydric alcohol with water or alcohol, and a step of impregnating the wood material with the impregnation treatment solution. This process consists of heating and pressurizing the wood in a wet state to react with the treatment liquid and simultaneously compact the wood material. Thin boards such as sawn boards and veneers are suitable as the wood material to be modified.

In addition, the polybasic acids used as the treatment liquid include maleic acid, fumaric acid, succinic acid, phthalic acid, isophthalic acid, terephthalic acid,
Trimellitic acid, pyromellitic acid, citraconic acid, ethylene acid, etc. are used, and also maleic anhydride, succinic anhydride, phthalic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl A polybasic acid obtained by reacting a polybasic acid anhydride such as hexahydrophthalic anhydride with water or alcohol may also be used.

Examples of polyhydric alcohols include propylene glycol, ethylene glycol, butanediol, diethylene glycol, dipropylene glycol, ethylenediol, pentadiol, trimethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and phenylglycerin.

The treatment liquid is prepared by mixing water or alcohol with a polybasic acid (in the case of polybasic acid anhydride, water or alcohol is reacted to form the polybasic acid) and polyhydric alcohol. It is preferable to appropriately select and use a combination that is soluble in water, which is a solvent, but if it is not soluble in water, alcohol is used to dissolve it.

Although it is disadvantageous in terms of cost to use alcohol other than water as a solvent, it is possible to use a highly concentrated reaction solution that can sufficiently react with or in wood, even with polybasic acids that are insoluble or poorly soluble in water. There are advantages to being able to create The same can be said of polyhydric alcohols; even polyhydric alcohols that are insoluble in water can be dissolved if alcohol is used as a solvent, so they can be easily injected and impregnated into wood planks.

The method of injecting the treatment liquid into wood depends on the species of wood,
Depending on the board thickness, etc., a method of applying the treatment liquid to the wood material, a method of immersing the wood material in the treatment liquid, or a method of applying pressure under reduced pressure, under pressure, or under reduced pressure may be adopted as appropriate. If the treatment liquid is not sufficiently impregnated, the effect will be reduced, so it is desirable to inject by the pressure reduction/pressure method.

In the case of reduced pressure/pressure injection, injection may be difficult due to the solubility, melting point, boiling point of the solvent, etc., so it is necessary to appropriately consider the combination of solvents and solutes.

The wood material that has been injected and impregnated with the treatment solution can be used as is, or after preheating, it can be used to create baseboards, wood substrates such as particle boards, fiberboards, inorganic substrates such as cement boards, gypsum boards, silica boards, etc. It is placed on a suitable base plate such as a metal plate or a synthetic resin plate, and heat and pressure treatment is performed in a wet state in which active groups such as hydroxyl groups in the wood component are in contact with the treatment liquid.

The heating temperature at this time is 100~250''C2, preferably 1
The temperature is 40 to 210°C, and the pressure and processing time vary depending on the tree species and the thickness of the wood board, but the pressure is several tens of kg.
/c+f1 or more, the processing time is set to several minutes to several hours, preferably 5 minutes to 120 minutes.

When a wood board impregnated with the treatment liquid is treated under heat and pressure, the polybasic acid in the treatment liquid decomposes into acid anhydride and water, and the acid anhydride esterifies with the active groups in the wood components. react,
It becomes plasticized and becomes deformable. Therefore, compared to untreated wood, the compressive stress is reduced and the wood is easily compressed and deformed, and when placed on a base plate and compressed, the treated wood is selectively consolidated.

At this time, polybasic acids usually need to be reacted at normal pressure and high temperature in order to decompose into acid anhydrides and water, but since the reaction is carried out under high pressure inside the wood, even heating temperatures below the decomposition reaction temperature can be used. Decomposition is possible.

When the acid anhydride of a polybasic acid undergoes an esterification reaction with the active group in the wood component, the lignin, etc. in the wood component is reduced in molecular weight by solvolysis under acidic and high temperature conditions, resulting in fluidity. As a result, the wood grain appears to flow and curve, and is fixed by the thermosetting material in a state where the wood grain pattern has changed to a new wood grain pattern different from that before heating and pressing. This plastic deformation varies depending on the degree of compaction of the wood material, and as the pressure increases, more thermosetting substances penetrate into the voids of the wood, which can increase transparency and densification.

The generated thermosetting resin component, which imparts transparency, becomes diluted when the proportion of water as a solvent is increased, resulting in a decrease in the fluidity of lignin, etc., and a tendency for the color of the material to become lighter.

For example, if a hemlock veneer with a thickness of 1.5 mm is compacted to about 1/2 of the thickness, a curved wood grain pattern can be obtained.

In addition, after impregnating the wood material with the treatment liquid, uniform compaction can be easily achieved by preheating the wood material for several minutes to several tens of molecules in an uncompacted state before the compaction treatment.

In addition, if cracks, pinholes, or warpage occur in the wood material when solvents such as water escape due to heat pressure, this can be prevented by combining heat pressure and deaeration or by using a cushioning material.

When the wood material impregnated with the treatment liquid is compacted in this way, as described above, the active groups such as hydroxyl groups in the wood components undergo an esterification reaction with the acid anhydrides of polybasic acids, and at the same time, the polyhydric alcohol This creates a thermosetting resin that chemically bonds with the wood components within the wood, and solidifies as this thermosetting material penetrates into the voids of the wood, creating a dense resin with depth and luster with increased transparency. layers are formed.

In this process, if the pressure and temperature are increased and the treatment time is increased, the fluidity and transparency of the wood grain will be further enhanced, resulting in a plastic-like appearance, and the autumn wood will become darker and the spring wood will become darker. It gives a special appearance with pale parts.

In the above embodiments, wood plate-like materials have been described as the wood to be modified, but if a base plate is placed in advance, it can be used not only for plate-like materials but also for small pieces of wood such as flakes and chips, thin pieces of wood, or wood powder. Even wood materials can be modified with good workability.

In this case, if the wood material consists of small wood pieces or thin board pieces such as flakes or chips, it is sufficient to arrange a plurality of pieces on the baseboard in an appropriate arrangement; What is necessary is just to laminate them so that a deposited layer of a constant thickness is formed thereon.

If the baseplate is made of wood or synthetic resin, the surface of the baseplate will also be chemically treated by the seepage of the thermosetting substance generated in the wood layered on top of it, resulting in good adhesion at the interface between the two. This is the result. In this case, the wood material impregnated with the treatment liquid is heated and pressurized on the base plate, so even small pieces of wood such as flakes and chips will adhere firmly to the base plate due to the self-adhesive properties of the thermosetting substance produced. This will form a modified surface layer of the wood material.

In addition, when performing the heating and pressurizing treatment, a back-up material for preventing warpage may be provided on the back surface of the base plate.

On the other hand, in cases where the base plate is made of a thermosetting material such as a metal plate and has insufficient adhesion, wood materials impregnated with a treatment liquid may be laminated on such a base plate via an adhesive such as urethane or phenol resin. Afterwards, heat and pressure treatment may be performed. In this way, when a metal plate is used as the base plate, when the wood material impregnated with the treatment liquid is heat-pressured and integrated with the base plate,
Utilizing the plasticization of the wood material, it is possible to draw the wood material using a heating mold material or to form an appropriate uneven pattern without causing cracks in the wood material.

Note that formation of such an uneven pattern is possible even when the base plate is made of wood or resin.

Next, specific examples of the present invention will be shown.

Example 1 A treatment liquid prepared by mixing maleic anhydride: glycerin: water in a ratio of 2:1:1 (weight ratio) was prepared to a thickness of l.

The mixture was injected into a Japanese hemlock veneer with a width and length of 10 On+m by a reduced pressure/pressure method, and then preheated at 210°C for 10 minutes in an unpressed state.

This treatment liquid injected veneer has a thickness of 9R11Il and a width of 100II.
III+, placed on a base plate with a length of 100 mm and inserted between the upper and lower heating plates through 8 mm thick spacers on all sides, temperature 200'C1 set pressure 100 kg/cI1
In Step 1, the veneer was hot-pressed for 60 minutes to consolidate it, and a laminate in which the veneer was integrally adhered to the base plate was obtained.

The thus obtained laminated material had the wood grains of the veneer on the surface forming a flowing pattern (sliding pattern), and had a deep and glossy appearance with added transparency.

Furthermore, the veneer forming the surface layer had a dense smooth surface and was excellent in abrasion resistance, water repellency, dimensional stability, and durability. Furthermore, no peeling or warping occurred even when immersed in water.

Furthermore, when infrared absorption spectrum analysis was performed on a veneer that had only been preheated after being injected with the above-mentioned treatment liquid, chemical modification of carboxyl groups to the wood was observed.

Therefore, at the stage when the treatment liquid injected veneer is heated and pressed,
It is thought that maleic acid decomposes into maleic anhydride and water inside the wood, and the resulting maleic anhydride easily causes an esterification reaction with the wood and also causes a crosslinking reaction with glycerin.

Example 2 The same treatment solution as in Example 1 was applied to the hemlock wood flour in an amount of 10.
It was applied and impregnated by spraying at a ratio of 0% (wood flour weight ratio).

This treatment solution-impregnated wood powder was deposited on the surface of the base plate made of the same base plate as in Example 1, and was inserted between the upper and lower heating plates to a temperature of 200.
°C1 set pressure 100kg/cI11. Hot pressure was applied for 60 minutes. At this time, a spacer of an appropriate height was interposed between the upper and lower heating plates to adjust the compressed thickness of the treatment liquid-impregnated wood flour to a desired thickness.

As a result, a laminated material was obtained in which a transparent wood material layer having a pattern of melted and flowed wood powder was integrally layered on the surface of the base plate. The wood layer of the laminated material formed from wood flour was dense and extremely hard.

〔Effect of the invention〕

As described above, according to the method for manufacturing a plate having a modified wood surface layer according to the present invention, since the treatment liquid used is water or an alcohol solvent, it has a high affinity with wood which is hydrophilic. It can easily penetrate into the fine pores in the wood and make good contact with the active groups such as hydroxyl groups in the wood components. When the wood impregnated with this treatment liquid is heated and pressurized, many of the components in the treatment liquid are removed. Basic acid decomposes into acid anhydride and water,
The acid anhydride undergoes an esterification reaction with the active groups in the wood components to plasticize it, and at the same time crosslinks with the polyhydric alcohol to produce a thermosetting substance that binds to the wood components within the wood, leaving the wood in a compacted state. It can be fixed with.

Furthermore, during this compaction, the lignin, a wood component, becomes lower in molecular weight and flows, and as a result, the wood grain flows as if it were sliding, making it possible to change to a new wood grain pattern different from that before heating and pressing. Low-molecular lignin and the above thermosetting substances penetrate into the voids of the wood and solidify, increasing transparency and forming a dense layer with depth and luster, making it resistant to abrasion and cracks. Modified wood with improved properties and water repellency can be obtained.

Furthermore, since the thermosetting substance is a resin chemically bonded to wood components, it is firmly integrated with the wood and the base plate, and hardly deforms or peels even when immersed in water etc. , exhibits excellent dimensional stability.

In addition, by utilizing the fact that the above-mentioned treatment liquid combines with wood components in wood to generate a thermosetting substance having adhesive properties, it is possible to produce wood plate-like objects, small pieces of wood, etc. impregnated with the treatment liquid that generates this thermosetting substance. The wood material can be easily integrated onto the base plate by heating and pressurizing, and it is possible to obtain a decorative board with a variety of changes having the above-mentioned improved physical properties.

Claims (1)

[Claims] (1) Impregnate the wood material with a treatment solution made by mixing polybasic acid and polyhydric alcohol with water or alcohol, place the wood material on the surface of the base plate, and leave it wet with the impregnation treatment solution. A method for producing a plate-like article having a modified wood surface layer, which comprises heating and pressurizing the resulting thermosetting substance to harden it and integrating it into a base plate.