JPH02155604A - Preparation of modified wood - Google Patents

Abstract

PURPOSE:To reduce the deformation of wood accompanying the moisture absorbing properties, to enhance dimensional stability and to reduce the deterioration of material quality by impregnating wood having a specific range of acetylation degrees with a hydrophobic easily polymerizable substance and subsequently polymerizing said substance by heating. CONSTITUTION:After a wooden material having an acetyl value of 15-20% is impregnated with a hydrophobic easily polymerizable substance, the hydrophobic easily polymerizable substance is polymerized by heating. As an acetylation agent, acetic anhydrie, ketene, acid chloride or the like are pref. used from the viewpoint of the deterioration of material quality after modification. In acetylation, in the presence of a usual basic substance as catalyst, a compound selected from basic amine or amine type compounds having the swelling coefficient to wood larger than thtat of water and having swelling capacity to wood is used. As the amine or amide type compounds, dimethylformamide or the like can be designated. These amine or amide type compounds can perform the esterification reaction of wood in a state further swollen as compared with such a state that wood absorbs water to be swollen.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for chemically modifying wood, and in particular, after impregnating a wood material having a degree of acetylation within a specific range with a hydrophobic easily polymerizable substance, The present invention relates to a method for producing modified wood, which comprises heating and polymerizing the easily polymerizable substance.

<Conventional technology> Compared to other materials, wood has a high specific strength, high elasticity, good adhesive properties, and is easy to process, so it is used as a material for various constructions,
It is used for a wide range of purposes, including furniture materials. On the other hand,
It has fatal drawbacks such as non-uniformity of material, decay, moisture absorption, and accompanying deformation. For this reason, various material improvement methods have been studied and carried out in the past. Among them, the method of treating wood with various alkaline acetylating agents reduces the deformation caused by the hygroscopicity of wood and at the same time reduces the decay resistance. It is attracting attention as a method for improving the quality of wood, as it has the advantage of contributing to improving the quality of wood.

This method reduces moisture absorption by substituting the hydroxyl groups in wood with hydrophobic groups, since the moisture absorption of wood is caused by the bonding of water molecules with wood-loving groups, especially hydroxyl groups, present in wood constituents. At the same time, this method provides dimensional stability of +1 by reducing swelling/shrinking adhesion.

On the other hand, the composite technology of wood and synthetic resin in which the wood is immersed in an easily polymerized liquid or the easily polymerized substance liquid is injected into the board pipes in the wood under reduced pressure is also a method for chemically modifying wood. It is already widely used as

This modification method is widely known as synthetic resin-injected wood, and has a great influence on improving mechanical properties and imparting dimensional stability.

<Invention or Problem to be Solved> However, this method has limitations in terms of mechanical properties and dimensional stability because easily polymerizable substances are simply polymerized or condensed in the fine structure of wood. There was.

The inventors of the present invention have conducted extensive research to solve these drawbacks of the conventional technology.
・As a result of our research, we discovered that by impregnating wood with a degree of acetylation within a specific range with a hydrophobic, easily polymerizable substance and then heating and polymerizing it, the stability of the wood using the ・1 method could be significantly improved. The invention has been achieved.

Therefore, the first object of the present invention is to provide a method for modifying wood to reduce deformation due to hygroscopicity of wood and increase dimensional stability. The objective is to provide a method for modifying wood.

<Means for Solving the Problems> The above-mentioned aspects of the present invention are to make the wood itself hydrophobic by replacing the OH groups in the wood with acetyl groups, and further to add a hydrophobic easily polymerizable substance in the microstructure of the wood. This was achieved by polymerization.

The acetylating agent used to acetylate wood in the present invention can be appropriately selected from known compounds that normally react with hydroxyl groups, but is particularly suitable for reducing material deterioration after modification. From this point of view, it is preferable to use acetic anhydride.

Examples of such acetylating agents include acetic anhydride, kedene, and acid chlorides.

When carrying out acetylation using an acetylating agent such as "Biped", a basic substance is usually used as a catalyst. In the present invention, at least one compound selected from amine-based or amide-based compounds whose swelling coefficient for wood is larger than that of wood is selected and used. These compounds are
Since it is basic and has the ability to swell wood, it functions as a catalyst in the acetylation reaction.

Examples of the amine or amide compounds used in the present invention include n-phthylamine, piperidine, pyridine, and dimethylformamide. These amines have a swelling coefficient for wood that is larger than that of water, so that the esterification reaction of wood can be carried out in a state where the wood is more swollen than the state where the wood is swollen by absorbing ice.

Furthermore, since the amine used also functions as an esterification reaction catalyst, there is no need to use conventional catalysts that cause material deterioration of wood.

It is preferable that the amount of amine etc. to be used is such that it can exhibit its swelling function, or that it is usually used in an amount of at least 5% or more based on the esterifying agent. The esterification reaction in the present invention can be carried out according to known conditions.

When acetylating wood, if the degree of acetylation is low, the amount of hydrophobic groups introduced into the wood will be small and the modification effect will not be sufficient.On the other hand, if the amount of hydrophobic groups is large, material deterioration will easily occur, and hydrophobic A range of 15 to 20% is preferable because the impregnating properties of easily polymerizable substances are markedly reduced and unevenness tends to occur after heating polymerization.

In the present invention, after the acetylation reaction was completed, extraction was performed using hot water and acetone at a temperature of 80°C for 8 hours, and the following results were obtained.

Acetylation degree (%) = W 2 W + X 100
I W, ・Untreated material hot water/acetone extraction contact dry weight W2 ・
Acetylated material hot water/acetone extraction contact bone dry weight Note that during acetylation, it is advisable to perform a treatment such as acetone extraction or hot water extraction in advance in order to remove the influence of extracted components in the wood.

Example 1 Japanese pine square supplement block material (5X: 15X 35mm) subjected to acetone extraction (80°C 8Hrs, 2 times) and hot water extraction (80°C 3TLrs, 2 times) was mixed with 70 parts by weight of acetic anhydride and 30 parts by weight of pyridine. After the acetylation reaction (120°C, 560 minutes), the mixture was immersed in a mixed solution consisting of 300ml, 13.5L and 15.2LL.
An acetylated block material having a content of 8.9L and 21.7L and 25.6% was obtained. Next, 30 parts by weight of methyl acetate was added to 50 parts by weight of a reprinted unsaturated polyester resin in which 2 parts by weight of benzoyl peroxide was added to this acetylated block material.
A hydrophobic polymeric substance liquid consisting of 20 parts of toluene was depressurized.
The results shown in Table 1 were obtained regarding the relationship between the degree of acetylation, suitability for impregnation, and unevenness of impregnation of the modified wood obtained by impregnation using a pressure method and then heating polymerization using a conventional method.

[Test method code] 1. Impregnation unevenness and material deterioration are determined by visual inspection.

2. Anti-swelling ability T (tangential) direction, R (
The dimensional change in the (radial) direction before and after the water absorption test (20°C, 124 hours) was measured and calculated using the following formula.

Anti-swelling ability (%) = V-V, xiOO■・Untreated material R, T direction test piece size ■1; Modified material R, T direction test piece size comparison example 1 Same as Example 1, acetone extraction (80 °C811rs,
x2 times) and hot water extraction (80°C, 81trs, x2 times)
Treated rice pine four-sided supplementary block material (5x 35x
Acetylation reaction (1
After drying after 2 (1'C 160 minutes), the degree of acetylation was 18.9%.
An acetylated flock material having a similar anti-swelling n
! When the power is fixed to Al1, it is 70% in the T direction and 68% in the R direction.
%Met.

Comparative Example 2 Acetone extraction (80'C8firs,
Rice pine square supplement block material (5x 35x3) treated with hot water extraction (80℃81bs, x2 times)
5 mm) was impregnated with a hydrophobic polymeric material liquid consisting of 30 parts by weight of methyl acetate and 20 parts by weight of toluene into 50 parts by weight of a reprinted unsaturated polyester resin to which 2 parts by weight of benzoyl peroxide had been added, by a vacuum-pressure method, and then heated by a conventional method. Polymerization was carried out to obtain a modified wood having a resin impregnation amount of 134%, and the anti-swelling ability was measured in the same manner and found to be 28% in the T direction and 30% in the R direction.

<Effects of the Invention> According to the present invention, modified wood can be produced by mixing a hydrophobic polymeric substance with a wood material having a degree of acetylation of 15 to 20% without causing material deterioration. Since hydrolysis is suppressed, it is possible to produce highly moisture-resistant wood with excellent overall dimensional stability.

That is, according to the modified wood production method of the present invention, the water-resistant groups in the wood are replaced with acetyl groups to make the next month components hydrophobic, and in addition, water is prevented from entering inside the wood cell walls. Due to the effect of heavy weight, it is possible to produce wood with excellent moisture resistance compared to conventional methods.

Cow V Ii 乍 mourning people

Claims (1)

[Claims] A method for producing modified wood, comprising impregnating a hydrophobic easily polymerizable substance into a wood material having a degree of acetylation of 15 to 20%, and then heating and polymerizing the hydrophobic easily polymerizable substance.