JPH01182002A - Manufacture of modified timber - Google Patents

Abstract

PURPOSE:To infiltrate low-molecular lignin and a heat-curing material into the spaces of timber to be solidified therein and enhance wear resistance, resistance to cracking and the like by impregnating plate-shaped timber with a treatment solution composed of polyacidic acid and polyvalent alcohol mixed with water or alcohol, and heating and pressurizing the same in the wet state. CONSTITUTION:Solution composed of a mixture of 2 part by weight of maleic anhydride as polyacidic base acid, glycerin of 1 part by weight as plyvalent alcohol and water of 2 part by weight is injected into a hemlock sprue veneer by means of the vacuum pressurizing method. Said treated solution injected veneer is preheated at the temperature of 170 deg.C in the incompressed state for 5 minutes, and then inserted between upper and lower platens and heated with the pressure of 50kg/cm<2> and at the temperature of 210 deg.C for 100 minutes to manufacture a modified timber, with its grains in folded patterns and rich in resistance to wear and of superior dimension stability when being impregnated in the water.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for producing modified wood that can chemically modify wood and at the same time compact it to impart new rich cosmetic properties to the wood. It is related to.

[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, thin wood boards are 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. It is used to transform wood into thin boards.

[Problems to be Solved by the Invention] However, according to this method, the steps of amorphizing the cellulose in the wood thin plate using a reactant capable of reacting with the hydroxyl groups in the wood components, such as an esterifying agent or an etherifying agent, and This process requires a step of heating and pressurizing the chemically treated thin wood board, which is particularly time-consuming and has poor productivity. In order to accelerate the reaction between wood and wood components, catalysts such as sulfuric acid and perchloric acid are required, which not only complicates the process, but also causes the reaction of wood components to occur when organic acid anhydrides are used as esterifying agents. When hydroxyl groups and the like react, by-products remain in the material, resulting in production problems such as the need for washing and drying treatments.

The present invention simultaneously chemically modifies wood and consolidates it to easily plastically deform the wood, impart transparency and luster,
The present invention also provides a method for producing modified wood for the purpose of improving wear resistance and crack resistance.

[Means to solve the problem]

In order to achieve the above object, in the method for producing modified wood of the present invention, a wood board is impregnated with a treatment liquid prepared by mixing a polybasic acid and a polyhydric alcohol with water or alcohol,
The method is characterized in that the wood board-like material is heated and pressurized while it is wet with an impregnating treatment solution to harden the thermosetting material produced.

[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. When it solidifies, it becomes more transparent, forms a dense layer with depth and luster, and improves abrasion resistance, crack resistance, and water repellency.

〔Example〕

To explain in detail the embodiments of the present invention, the process includes a step of impregnating a wood board with a treatment liquid made by mixing a polybasic acid and a polyhydric alcohol with water or alcohol, and moistening the wood board with the impregnation treatment liquid. It consists of the process of heating and pressurizing the wood board while it is in a state to react with the treatment liquid and simultaneously compacting the wood board. Thin boards such as sawn boards and veneers are suitable for the wood board to be modified. It may be a plate-like object or a block object having a relatively thick thickness.

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 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. It has the advantage of being able to create The same can be said of polyhydric alcohols; even polyhydric alcohols that are insoluble in water can be dissolved by using alcohol as a solvent, so they can be easily injected and impregnated into wood planks.

The method of injecting the treatment liquid into the wood plate depends on the species of wood, the thickness of the wood, etc., and there are two methods: applying the treatment liquid to the wood plate, immersing the wood plate in the treatment liquid, or under reduced pressure. Pressurized or reduced pressure methods may be used as appropriate, but if the treatment solution is not sufficiently impregnated into the interior of the wood board,
Since the effect is reduced, it is preferable 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 plate material into which the treatment liquid has been injected and impregnated is subjected to heating and pressure treatment while in a wet state in which active groups such as hydroxyl groups in the wood components are in contact with the treatment liquid.

The heating temperature at this time is 100 to 250°C, 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+It 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.

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 the wood is fixed by the thermosetting substance in a state where it has changed into a new natural wood pattern different from that before heating and pressing. This plastic deformation varies depending on the degree of compaction of the wood board; the higher the pressure, the more thermosetting material will 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 consolidated to about 172 mm thick, a curved wood grain pattern can be obtained.

In addition, after impregnating the wood plate with the treatment liquid, uniform compaction can be facilitated by preheating for several minutes to several tens of molecules in an uncompacted state before consolidation treatment. In addition, if cracks, pinholes, or warpage occur in the wooden plate 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.

In this way, when a wood board impregnated with a treatment solution is compacted, as described above, active groups such as hydroxyl groups in the wood components and acid anhydrides of polybasic acids undergo an esterification reaction and, at the same time, polybasic acids. A thermosetting resin is produced that crosslinks with the alcohol and chemically bonds with the wood components within the wood, and this thermosetting resin solidifies while penetrating into the voids of the wood, giving it depth and luster with increased transparency. A dense layer is 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.

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 2:1:2 (weight ratio) was 1.5 (thickness) x 10
It was injected into a Japanese hemlock veneer measuring 0 (width) x 100 (length) by the vacuum/pressure method.

After preheating this treatment liquid-injected veneer for 5 minutes at a temperature of 170°C in an unpressed state, it was inserted between the upper and lower heaters and hot-pressed at a pressure of 50 kg/cIN and a temperature of 210°C for 100 minutes. Consolidation was performed with a thickness of about 2.

As a result, the wood grain of the veneer exhibits a curved pattern.

A hard veneer with a rich design and partially transparent was obtained.

Furthermore, this hard veneer had a dense and smooth surface, was highly abrasion resistant, and had excellent dimensional stability with almost no springback even when immersed in water.

Example 2 A treatment liquid-injected veneer obtained by the same treatment as in Example 1 above was preheated at a temperature of 210°C for 5 to 10 minutes in an unpressed state, and then heated at a pressure of 300 kg/cf and a temperature of 21°C.
Consolidation was performed by hot pressing at 0°C for 30 minutes.

As a result, a sheet-like cured veneer was obtained which was entirely transparent and had a flow pattern of wood grain and was rich in cosmetic properties.

In this way, transparency can be improved by increasing the processing pressure.

Furthermore, when infrared absorption spectroscopy was performed on a veneer that had only been preheated after being injected with the above-mentioned treatment solution, 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.

(Effect of the invention) As described above, according to the method for producing modified wood according to the present invention, since the treatment liquid used is water or an alcohol solvent, it has a high affinity with the hydrophilic wood. It easily penetrates into microscopic voids and can be brought into good contact with active groups such as hydroxyl groups in wood components, and when a wood board impregnated with this treatment liquid is heated and pressurized, the polybasic acid in the treatment liquid is removed. The acid decomposes into acid anhydride and water, and the acid anhydride undergoes an esterification reaction with the active group in the wood component to plasticize it, and at the same time crosslinks with the polyhydric alcohol and bonds to the wood component within the wood. A thermosetting material can be produced to fix the wood slab in a compacted state.

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.

In addition, since the above thermosetting substance is a resin chemically bonded to wood components, it is strongly integrated with the wood, hardly deforming even when immersed in water, etc., and exhibits excellent dimensional stability. It is something to do.

Claims (1)

[Claims] (1) Impregnating a wood plate with a treatment liquid made by mixing polybasic acid and polyhydric alcohol with water or alcohol, heating and pressurizing the wood plate while moistened with the impregnation treatment liquid, A method for producing modified wood, characterized by curing a thermosetting substance produced.