JPH05269707A - Manufacture of modified lumber - Google Patents

Abstract

PURPOSE:To enable an improvement in productivity and a reduction of cost, by a method wherein formalizing reaction is performed uniformly up to the inside of lumber even if raw material lumber is thick. CONSTITUTION:A lumber veneer which is under almost a dried state is put into a pressurizable reaction vessel whose temperature rise is performed beforehand. Trioxane is put into the reaction vessel by such quantity as the density of 30-300mol/m<3> per capacity of the reaction vessel is attained by converting into a holmaldehyde monomer. Then the vessel is closed tightly and the inside of the vessel is made into a decompressed state by making use of a vacuum pump. Immediately after that, sulfur dioxide SO2 is introduced. Hormalizing reaction is made to perform after that. Then residual gas within the reaction vessel is decompressed and exhausted sufficiently and modified lumber is obtained. With this construction, since a rate of reaction is high, modified lumber which is superior in various functions such as dimensional stability, water resistance, weather resistance, stainproofness, corrosion proofness and insectproofness can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing modified wood used as housing equipment, building materials and the like.

[0002]

2. Description of the Related Art Formalization has long been performed as one of methods for imparting dimensional stability to wood. Formalization is a reaction in which the hydrophilic hydroxyl groups of wood components (cellulose, hemicellulose, lignin, etc.) are crosslinked with formaldehyde. The hydrophilicity of wood is reduced by such cross-linking, and the weight increase rate is as low as 5 to 10%.
High dimensional stability of ~ 60% can be obtained.

In the conventional formalization treatment method, formaldehyde derivatives such as paraformaldehyde, trioxane and tetraoxane are used as a formaldehyde supply source, and sulfur dioxide, hydrogen chloride, zinc chloride, iron chloride, magnesium chloride and chloride are used as a formalization reaction catalyst. A raw material wood was heated in a gas phase or a liquid phase in a reaction vessel using a chloride such as ammonium, a sulfate such as iron sulfate, and an acid catalyst such as boric acid and borate. In particular, when trioxane or tetraoxane is used as a formaldehyde supply source, and sulfur dioxide is used as a reaction catalyst, and when gas phase treatment is performed using iron sulfate or the like as a co-catalyst for promoting decomposition of the trioxane or tetraoxane into formaldehyde, It is said that discoloration and strength deterioration due to acid are small.

[0004]

However, the wood formalized by the above-mentioned conventional method has a formalization reaction only up to about 2 to 3 mm from the surface of the wood and has a low reaction rate. Therefore, there is a drawback that sufficient performance cannot be obtained, especially when the thickness of wood becomes thick. In addition, when the ratio of the volume of wood to the volume of the reaction vessel is increased, the amount of formaldehyde derivative per wood becomes relatively low, so that sufficient performance cannot be obtained and the discoloration of wood becomes large. ..

Therefore, according to the present invention, even if the raw material wood is thick, it is possible to cause the formalization reaction even inside the wood, and since the reaction rate is high, excellent performance such as high dimensional stability is achieved. It is an object of the present invention to provide a method capable of improving the productivity and reducing the cost, since the ratio of the volume of wood to the volume of the reaction vessel can be increased while the modified wood of the present invention can be obtained.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the inventors have made various studies. As a result, the present invention has been completed by confirming the following by experiments. That is,
If the vapor concentration of formaldehyde and / or its derivative is increased within a specified range, the penetration and diffusion of these vapors into the wood will be promoted, so even if the raw wood is thick, it will be even inside the wood. The formalization reaction can be carried out and the reaction rate is improved. In addition, it is possible to increase the ratio of the wood volume to the reaction vessel volume.

Therefore, the method for producing modified wood according to the present invention is a method for producing modified wood in which raw material wood is heated in the presence of steam of formaldehyde and / or its derivative and an acid catalyst. The vapor concentration is ³⁰ to 300 mol / m ³ in terms of formaldehyde monomer.

The raw material wood for reforming used in the present invention is not particularly limited. For example, raw wood logs,
Lumber products, sliced veneer, rotary veneer, plywood and the like can be mentioned. There is no limitation on the species of the trees. The raw material wood has been dried to remove excess water, for example, has a water content below the fiber saturation point, specifically 2
It is preferably 0% or less. This is because if there is excess water during formalization, the formaldehyde monomer is easily polymerized by this water to form an oxymethylene chain, and if it becomes an oxymethylene chain, the dimensional stability improving effect is reduced and the acid catalyst This is because the discoloration of the wood becomes large due to the action of and, which is not preferable.
However, some acid catalysts described in detail later require water. For example, in the case of sulfur dioxide, water is required because it reacts with formaldehyde to water to produce hydroxymethyl sulfonic acid, which promotes cross-linking between wood components. Therefore, when using a catalyst that requires water, it is preferable to adjust the degree of drying of wood.

Examples of the drying method for adjusting the water content of such wood include air drying, vacuum drying, hot air drying, high frequency heating, electron beam irradiation and the like, and are not particularly limited. You may use these methods together. The formaldehyde derivative used in the present invention means a formaldehyde supplier. The formaldehyde supply agent is not particularly limited, but examples thereof include those which generate a formaldehyde monomer by thermal decomposition such as paraformaldehyde, trioxane, and tetraoxane. These can use 1 type (s) or 2 or more types. Further, among these, trioxane and tetraoxane are advantageous in that they do not have a formalin odor when they are solid, they easily sublime, and formaldehyde monomers are easily obtained upon decomposition. Therefore, it is preferable to use trioxane and tetraoxane.

In the present invention, it is necessary to use an acid catalyst as the formalization reaction catalyst. The acid catalyst used is not particularly limited, but for example, sulfur dioxide, chlorides such as hydrogen chloride, zinc chloride, iron chloride, magnesium chloride, ammonium chloride, sulfates such as iron sulfate,
Examples thereof include boric acid and borate. Among these acid catalysts, particularly when sulfur dioxide is used, it is desirable to use sulfur dioxide because the strength deterioration and discoloration of wood become relatively small. The acid catalyst may be used alone or in combination of two or more.

In addition to the effect of promoting the formalization reaction, the above-mentioned acid catalyst also has the effect of promoting the decomposition of formaldehyde derivative into formaldehyde monomer. Therefore, if necessary, two or more kinds of acid catalysts are used, some of them are mainly used as co-catalysts for promoting decomposition into formaldehyde monomers, and the rest are used as formalization reaction catalysts. Good. For example, iron sulfate may be used mainly as a decomposition promoter to formaldehyde monomers, and sulfur dioxide may be used as a formalization reaction catalyst. It is also possible to use a catalyst other than an acid catalyst as the co-catalyst for promoting the decomposition of the formaldehyde derivative into formaldehyde monomer.

Formaldehyde and // for acid catalysts
Alternatively, the molar ratio of the derivative is preferably in the range of 10 to 100 in terms of formaldehyde monomer. If this molar ratio exceeds 100, the reaction rate of formalization is lowered because the amount of the acid catalyst is too small, and there is a tendency that a formalin odor remains or modified wood having sufficient performance cannot be obtained. When the molar ratio is less than 10, the amount of the acid catalyst is too large, so that the discoloration of the wood becomes large, the aesthetics and texture of the wood are lost, and the strength deterioration of the wood tends to be large. is there.

The reaction conditions for formalization are not particularly limited. For example, the heating temperature of wood is 90 to
120 ° C. is preferred. The pressure of the atmosphere of wood is 500-2
000 torr is preferable, and 760 to 2000 torr is more preferable. When formalization is carried out under such a pressure, the penetration and diffusion of formaldehyde into the wood is promoted, which makes the wood thickness and treatment amount of treatable wood larger and the reaction rate per weight of wood. Is also higher.

Formalization of wood is usually carried out in a reaction vessel (reaction tank). As described above, the formalization may be carried out under reduced pressure or increased pressure, and in that case, the reaction vessel needs to have pressure resistance. The method for producing the modified wood of the present invention is not particularly limited, but is performed as follows, for example.

First, a predetermined amount of raw material wood and formaldehyde derivative are put into a heated reaction vessel. When a liquid or solid acid catalyst is used, at this time, a predetermined amount is put together in the reaction vessel. The inside of the container is depressurized using a vacuum pump. The degree of pressure reduction at this time is preferably 300 torr or less. Then, the vacuum pump is stopped and the reaction container is heated and maintained at a predetermined temperature. When a gaseous acid catalyst is used, this heating and holding is carried out after introducing a predetermined amount of the acid catalyst into the reaction vessel.

Next, after heating for a predetermined time to carry out the formalization reaction, the gas in the reaction vessel is exhausted under reduced pressure while being heated. By sufficiently exhausting this gas, most of the unreacted gas in the wood can be removed. Modified wood is obtained from the above steps.

[0017]

When the raw material wood is heated in the presence of the vapor of formaldehyde and / or its derivative and the acid catalyst, the formaldehyde monomer (HCHO) and the acid catalyst diffuse and penetrate into the wood, and the following formula The formalization reaction represented by Chemical Formula 1 proceeds, and formaldehyde crosslinks between the hydrophilic hydroxyl groups of the wood component.

[0018]

[Chemical 1]

(Wherein R- (OH) _n represents a wood component), the hydrophilicity of wood decreases. As a result, the amount of water absorbed by the wood decreases, and the expansion of the wood due to the water absorption decreases, and the amount of water evaporation during drying decreases. Dimensional stability is improved. In addition to the dimensional stability, the formalization also imparts water resistance, weather resistance, antifouling properties, antiseptic / insect proof properties, and the like.

According to the invention, formaldehyde and / or
Alternatively, the vapor concentration of the derivative is converted to formaldehyde monomer to be ³⁰ to 300 mol / m ³ . Then, since the penetration and diffusion of these vapors into the wood are promoted, even if the raw wood is thick, it becomes possible to cause the formalization reaction even inside the wood, and the reaction rate is Since it becomes higher, it becomes possible to obtain modified wood excellent in the above-mentioned various performances. Further, since the ratio of the treated wood volume to the reaction vessel volume can be increased while maintaining the required amount of chemicals per wood, the productivity is improved and the cost is reduced.

If the concentration of the vapor of formaldehyde and / or its derivative is less than 30 mol / m ³ in terms of formaldehyde monomer, the vapor becomes difficult to permeate and diffuse into the wood, so that only near the wood surface. Since the formalization reaction does not occur and the reaction rate becomes low, sufficient performance cannot be obtained and it becomes difficult to process thick material. In addition, when the ratio of the volume of wood to the volume of the reaction vessel is increased at such a low concentration, the amount of formaldehyde derivative per wood becomes relatively low, so sufficient performance cannot be obtained and the discoloration of wood becomes large. Become.

If the vapor concentration of formaldehyde and / or its derivative exceeds 300 mol / m ³ in terms of formaldehyde monomer, the pressure inside the reaction vessel becomes too high, and a high pressure resistant reaction vessel should be used. Therefore, the cost is high.

[0023]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples. -Example 1-Width 180 mm x thickness 2 mm x length 400 in a substantially dry state
15 mm wood veneer was placed in a preheated and pressurizable 20 liter capacity reaction vessel, and trioxane was converted into formaldehyde monomer (HCHO) in the reaction vessel and the reaction vessel volume was 50 mol / m 2. Only the amount of ³ was added. Next, the container was sealed, and the inside of the container was depressurized (50 torr) using a vacuum pump. Immediately thereafter, SO ₂ was added at 5 mol / m ³ per reaction vessel volume.
It was introduced only in the amount to achieve the concentration. After that, the temperature is 120 ℃
The mixture was kept at 16 ° C. for 16 hours to carry out the formalization reaction. The final pressure in the container at that time was 760 torr.
Next, the residual gas in the reaction vessel was sufficiently evacuated under reduced pressure to obtain modified wood.

-Examples 2-6- Modified wood was obtained in the same manner as in Example 1 except that the concentrations of trioxane and SO ₂ and the reaction temperature were changed as shown in Table 1 below. However, in Example 6,
Ferric sulfate Fe ₂ (S) as a co-catalyst for promoting the decomposition of trioxane into formaldehyde monomer
O ₄ ) ₃ was used in an amount to give a concentration of 0.3 mol / m ³ per volume of the reaction vessel.

-Comparative Example 1-In Example 1, the concentration of trioxane was changed as shown in Table 1 below, and ferric sulfate Fe ₂ (as a co-catalyst for promoting decomposition of trioxane into formaldehyde monomer). Modified wood was obtained in the same manner as in Example 1 except that SO ₄ ) ₃ was used in an amount that would give a concentration of 0.3 mol / m ³ per volume of the reaction vessel.

[0026]

[Table 1]

In Table 1, the concentration of trioxane is converted into the amount of formaldehyde monomer (HCHO). The modified woods obtained in the above Examples 1 to 6 and Comparative Example 1 were subjected to a water saturation treatment and a total dry treatment to obtain the weight and size of each wood, and from these values, the following formula (1) was used. The impregnation rate represented and the anti-swelling ability (ASE) represented by the following formula (2) were determined.

Impregnation rate (%) = {(W ₂ −W ₁ ) / W ₁ } × 100 (1) (In the formula (1), W ₁ represents the total dry weight of the raw material wood, and W ₂ is the modified material. It represents the total dry weight of wood.) Anti-swelling capacity (%) = {(S ₁ −S ₂ ) / S ₁ } × 100 (2) (In the formula (2), S ₁ represents the swelling ratio of the raw wood. , S ₂ represents the swelling ratio of the modified wood.) The larger the value of the anti-swelling capacity (%), the higher the dimensional stability.

The results are shown in Table 2 below.

[0030]

[Table 2]

As shown in Tables 1 and 2, it was confirmed that when the concentration of trioxane was too low, both the impregnation rate and the dimensional stability were lowered. -Example 7- Width 160 mm x thickness 2 mm x length 400 in a substantially dry state
Fifteen mm wood cypress wood veneers were placed in a preheated, pressurizable 20 liter capacity reaction vessel. further,
In this reaction vessel, formaldehyde monomer (HCH
Amount of trioxane converted to O) to a concentration of 50 mol / m ³ per reaction vessel volume, and ferric sulfate Fe ₂ (SO ₄ ) as a co-catalyst for promoting the decomposition of the trioxane into formaldehyde monomer. ₃ was added in an amount to give a concentration of 0.5 mol / m ³ per reactor volume. Next, the container is hermetically sealed, and the inside of the container is depressurized (5
0 torr). Immediately thereafter, sulfur dioxide SO ₂ was used as a formalization reaction catalyst in an amount of 5 mol / volume of the reaction vessel.
Only the amount of m ³ was introduced. Then, increase the temperature to 120
The formalization reaction was carried out by holding at 16 ° C for 16 hours.
The final internal pressure at that time was 600 torr. next,
The residual gas in the reaction vessel was sufficiently evacuated under reduced pressure to obtain modified wood.

Example 8 Modified wood was obtained in the same manner as in Example 7 except that the amount of treated wood was reduced as shown in Table 3 below. —Examples 9 to 14— Modified wood was obtained in the same manner as in Example 7 except that the treatment conditions were changed as shown in Table 3 below.

Comparative Example 2 In Example 7, the concentration of trioxane is converted to formaldehyde monomer and the amount is 15 mol / volume of the reaction vessel.
Modified wood was obtained in the same manner as in Example 7 except that m ³ was changed. -Comparative Example 3-In Example 7, the concentration of trioxane was converted to formaldehyde monomer to be 15 mol / volume of the reaction vessel.
Modified wood was obtained in the same manner as in Example 7, except that m ³ was changed and the amount of treated wood was reduced as shown in Table 3 below.

[0034]

[Table 3]

[0035] Incidentally, in Table 3, the concentration of trioxane is obtained by converting the formaldehyde monomer (HCHO) amount, treated wood total volume timber volume / container volume for the reaction vessel volume (m ³⁾ of the (m ³⁾ Is the ratio. For the modified woods obtained in Examples 7 to 14 and Comparative Examples 2 to 3, the impregnation rate and the anti-swelling ability (ASE) were determined in the same manner as above. Further, using a color difference meter, the color difference change ΔE value (according to the Lab value) of each wood before and after the treatment was determined.

The results are shown in Table 4 below.

[0037]

[Table 4]

As shown in Tables 3 and 4, when the concentration of trioxane is too low, both the impregnation rate and the dimensional stability are lowered and the relative amount of the acid catalyst is increased.
It was confirmed that the discoloration of the wood was large (Example 7 to
14 and Comparative Example 2). Further, when the concentration of trioxane was too low, it was confirmed that the discoloration of the wood remained large though the impregnation rate and the dimensional stability could be improved by reducing the amount of treated wood (comparative example 2 and (Comparison with Comparative Example 3).

[0039]

EFFECTS OF THE INVENTION According to the method for producing modified wood according to the present invention, even if the raw wood has a large thickness, the formalization reaction can be uniformly carried out to the inside of the wood, and the reaction rate is high. It is possible to obtain a modified wood excellent in various properties such as stability, water resistance, weather resistance, antifouling property, antiseptic and insect repellency. Further, since the ratio of the wood volume to the reaction vessel volume can be increased, it is possible to improve productivity and reduce costs.

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[Procedure amendment]

[Submission date] July 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Next, after heating for a predetermined time to cause the formalization reaction, the gas in the reaction vessel is exhausted under reduced pressure while being heated. By sufficiently exhausting this gas, most of the unreacted gas in the wood can be removed. Modified wood is obtained from the above steps.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

[Chemical 1]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

(Wherein R- OH represents a wood component), the hydrophilicity of wood decreases. As a result, the amount of water absorbed by the wood decreases, and the expansion of the wood due to the water absorption decreases, and the amount of water evaporation during drying decreases. Dimensional stability is improved. In addition to the dimensional stability, the formalization also imparts water resistance, weather resistance, antifouling properties, antiseptic / insect proof properties, and the like.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoru Konishi 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Kenji Ohnishi, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co. 72) Inventor Ryusuke Honda 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (9)

[Claims] 1. A method for producing modified wood in which raw material wood is heated in the presence of formaldehyde and / or its derivative vapor and an acid catalyst, wherein the concentration of formaldehyde and / or its derivative vapor is converted to formaldehyde monomer. A method for producing modified wood, characterized in that it is ³⁰ to 300 mol / m ³ . 2. The method for producing modified wood according to claim 1, wherein the molar ratio of formaldehyde and / or its derivative to the acid catalyst is 10 to 100 in terms of formaldehyde monomer. 3. The method for producing modified wood according to claim 1, wherein the raw wood is heated under a pressure of 500 to 2000 torr. 4. The method for producing modified wood according to claim 3, wherein the raw wood is heated under a pressure of 760 to 2000 torr. 5. The method for heating raw material wood in a reaction vessel, and the ratio of the volume of the raw material wood to the volume of the reaction vessel is 0.01 to 0.2.
The method for producing modified wood according to any one of 1 to 3 above. 6. The method for producing modified wood according to claim 1, wherein the heating temperature of the raw wood is 90 to 120 ° C. 7. The method for producing a modified wood according to claim 1, wherein the water content of the raw wood is not higher than the fiber saturation point. 8. The method for producing modified wood according to claim 1, wherein the formaldehyde derivative is at least one selected from the group consisting of trioxane, tetraoxane and paraformaldehyde. 9. The acid catalyst is sulfur dioxide, hydrogen chloride, zinc chloride, iron chloride, magnesium chloride, ammonium chloride,
The method for producing modified wood according to any one of claims 1 to 8, wherein the modified wood is at least one selected from the group consisting of iron sulfate, boric acid, and borate.