JPH03268902A - Modification method of lumber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for modifying wood, and particularly to a method for improving the dimensional stability of wood.

(Prior art) Methods of modifying wood by etherifying or esterifying the hydroxyl groups in wood have been known for a long time, and esterification in particular has been commonly used as a method to increase the dimensional stability of wood. It is true.

However, this method has the disadvantage that it takes an extremely long time to carry out the esterification reaction sufficient for modification.

On the other hand, there is also a known method of plasticizing wood by carrying out alternating etherification and esterification reactions.

Thus, etherification reactions are generally unsuitable for improving the dimensional stability of wood.

(Problem to be Solved by the Invention) As a result of various studies on a method for producing modified wood that is simple and has high dimensional stability, the present inventors have found that the hydroxyl groups in the wood are etherified in advance with an etherification agent. By newly generating highly active hydroxyl groups and then esterifying the hydroxyl groups, it is possible to achieve esterification of wood in a short time. The inventors of the present invention have discovered that the dimensional stability of wood can be significantly reduced, thereby improving the dimensional stability of wood. .

Therefore, a first object of the present invention is to provide a method for modifying wood that does not cause material deterioration.

A second object of the present invention is to provide a method for modifying wood that can significantly reduce the degree of swelling of wood cells.

A third object of the present invention is to provide a method for modifying wood by esterification in a short time.

(Means for Solving the Problems) The above aspects of the present invention are characterized in that after etherifying the hydroxyl groups of wood with an etherifying agent, the hydroxyl groups generated by the etherification reaction are esterified with an esterifying agent. This was achieved through a wood modification method.

The present invention will be explained in detail below.

The wood used in the present invention is not particularly limited, and the modification method of the present invention can be applied to all types of wood.

As the etherification agent used in the present invention, it is preferable to use an epoxy compound from the viewpoint of the quality of the material after the reaction.

Examples of such epoxy compounds include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, and styrene oxide.

When wood is etherified using the above-mentioned etherification agent, a basic substance is usually used as a catalyst.
In the present invention, it is preferable to use at least one compound selected from amine-based or amide-based compounds whose swelling coefficient for wood is larger than that of water. Since it functions not only as a reaction catalyst for etherification using a compound but also as a swelling agent for wood, it is convenient for performing etherification quickly.

Examples of amine or amide compounds that can be used in the present invention include n-butylamine, piperidine,
Examples include pyridine, dimethylformamide, triethylamine, and the like. The mixing ratio of amine or amide compound to epoxy compound is 70/30 to 70/30 by volume.
Use in the range of 9515. When treating wood with an etherification reaction solution consisting of an epoxy compound and an amine or amide compound, it is carried out by a method such as immersing the wood in the reaction solution. The above treatment is usually carried out at a temperature of 100° C. or higher to promote the etherification reaction.

The degree of etherification of wood can be controlled by changing the length of the reaction time, and in particular, it is important to adjust the degree of etherification to 10 to 15% in terms of weight increase of the wood. Preferable from the viewpoint of improving dimensional stability. When the degree of etherification is lower than 10%, the degree of substitution of hydroxyl groups in the wood with epoxy groups is low, and subsequent esterification does not proceed in a short time, making it difficult to increase the degree of modification of the wood.

On the other hand, if the degree of etherification is higher than 15%, the subsequent esterification will proceed excessively in a short period of time, and the weight increase rate due to (etherification + esterification) to the wood will become extremely high, resulting in a very high degree of swelling. As a result of the increase in size, the wood deteriorates, resulting in a decrease in strength and physical properties.

After completion of the reaction, extraction treatment is performed once with hot water and acetone at 80° C. for 8 hours to remove wood extract components and unreacted etherification agent, and then heat drying treatment is performed.

Next, the hydroxyl group generated by the opening of the epoxy ring during the etherification reaction is esterified using an esterifying agent.

The esterification agent used in the reaction can be appropriately selected from known compounds that are known to react with hydroxyl groups.

From the viewpoint of material deterioration after modification, it is particularly preferable to use acetic anhydride, but other esterifying agents such as ketene and acid chloride may also be used.

In the esterification reaction using the above-mentioned esterification agent, the same basic substance as that used in the etherification reaction can be used as a catalyst. The mixing ratio of the esterifying agent and the basic substance is 60 to 90% by weight of the esterifying agent and 40 to 10% by weight of the basic substance.

When treating wood with an esterification reaction solution consisting of an esterification agent and a catalyst such as an amine or an amide compound, it can be carried out by a method such as immersing the wood in the reaction solution. In this case, the temperature is usually heated to 100°C or higher to promote the esterification reaction.

After the reaction was completed, extraction was performed once with hot water and acetone at 80°C for 8 hours to remove wood extract components, unreacted esterifying agent, and acetic acid produced, followed by heat drying. By doing this, the desired modified wood can be obtained.

By the above esterification treatment, hydroxyl groups in wood can be esterified.

(Effects of the Invention) As detailed above, according to the wood modification method of the present invention, hydroxyl groups in the wood are replaced with an etherifying agent in advance to generate new highly active hydroxyl groups, Since hydroxyl groups with a high concentration are esterified, the processing time for the esterification reaction can be significantly shortened compared to conventional esterification.

Further, since the bulking effect is increased by using the etherification reaction and the esterification reaction in combination, the degree of swelling of wood cells with respect to water is greatly reduced compared to the conventional method, and high dimensional stability can be obtained.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Agatis square block material and Japanese pine square block material (5x35 each
x35m+) was immersed in an etherification reaction solution consisting of 95 parts by weight of shrimp chlorohydrin and 5 parts by weight of triethylamine, and heated to 0.5 kg/crA at 120°C.
After etherification for 5 hours, 120% of
Esterification was carried out at 10°C for 5 hours. Next, after collecting the reaction solution, the test piece was dried to an absolutely dry state using a blow dryer, and the weight increase rate after modification (WP) was determined as follows.
G=Weight Percent Ga1n),
Bulking rate and anti-swelling ability (ASE = Anti-
Swelling Efficiency) was measured.

Table 1 Here, Wa is the bone dry weight of the treated wood, and Wb is the bone dry weight of the treated wood.

Here, RT is the bone-dry dimension of treated wood, RT.

is the bone-dry dimension of the treated wood.

Here, VRT is the dimensional change rate of unreacted wood, VRT,
is the dimensional change rate of the reacted wood.

The measurement results are shown in Table 1.

T: tangential direction, R: radial direction (hereinafter, the same applies to Tables 2 and 3).

Example 2゜Styrene oxide was used instead of epichlorohydrin used in Example 1, the etherification time was varied from 0.25 hours to 2.0 hours, and the esterification time was 0.5 hours. A test piece was prepared in the same manner as in the example except for the following.

Regarding the obtained test piece, ASE for the degree of etherification
The measurement results are as shown in FIGS. 1 and 2.

The results demonstrate that particularly good results are obtained when the degree of etherification is between 10 and 15%.

Comparative example 1゜ Only the etherification reaction was carried out under the same conditions as in Example 1.

The results are shown in Table 2.

Table 2 Comparative example 2゜ Only the esterification reaction was carried out under the same conditions as in Example 1.

The results are shown in Table 3.

The results of the Examples and Comparative Examples shown in Table 3 and above demonstrate that the dimensional stability of the modified wood obtained by the method of the present invention is extremely good.

[Brief explanation of drawings]

FIG. 1 shows the results of measuring ASE with respect to the degree of etherification of agathis treated by the modification method of the present invention. FIG. 2 shows the results of measuring ASE with respect to the degree of etherification of Japanese pine treated by the reforming method of the present invention. In the figure, O indicates the tangential direction, and * indicates the radial direction.

Claims (1)

[Scope of Claims] 1) A method for modifying wood, which comprises etherifying hydroxyl groups in wood with an etherifying agent, and then esterifying the hydroxyl groups generated by the etherification reaction with an esterifying agent. 2) The method for modifying wood according to claim 1, wherein the degree of etherification by the etherification agent is 10 to 15% in weight increase rate of the wood.