JPS6144601A - Method of decoloring wood - 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] (Technical field) The present invention relates to a method for decolorizing wood.

(Background Art) In general, when wood is left in its natural state, it is often oxidized by light processing and aeration, resulting in non-uniform coloring. To increase the added value of this refined wood, color toning is often performed. Toning generally includes bleaching and dyeing. The present invention is concerned with decolorization, which is a step before toning.

Things that can be used as decolorizing agents for wood include chlorine compounds,
Although there are many types such as hydrogen peroxide, hydrogen peroxide is commonly used. Hydrogen peroxide is an unstable compound and decomposes in the coexistence of highly tempered substances, alkalis, or metals. As a result, less hydrogen peroxide is used for dye decomposition. The oxidative decomposition reaction of the dye by hydrogen peroxide and the self-decomposition reaction of hydrogen peroxide are parallel reactions. By changing the ratio between this autolysis reaction and the dye oxidation reaction, hydrogen peroxide can be used effectively. However, conventional decolorization with hydrogen peroxide.

Since the method involved immersing the wood in a decolorizing solution containing hydrogen peroxide and an alkali and heating it, it was inevitable that a large amount of hydrogen peroxide would self-decompose.

(Purpose of the Invention) The present invention was proposed to improve the above-mentioned drawbacks, and it utilizes hydrogen peroxide effectively by changing the proportion of hydrogen peroxide consumed in the decomposition reaction and self-decomposition of the dye. The purpose is to reduce the cost of decolorization and shorten the time required for decolorization.

(Opening of the Invention) The present invention is a method in which the wood to be bleached is impregnated with alkali Vt in advance, and then the wood is immersed or coated in a hydrogen peroxide solution to bleach the wood.

The method of infiltrating wood with alkali in advance may be by immersing the wood in alkali or by applying alkali.

The alkalis that can be used here include alkali metals, alkaline earth hydroxides, carbonates, other salts, ammonia,
hydrazine.

Any alkaline material such as V-amine may be used. Applying alkali to wood can improve the liquid permeability of wood.

In particular, ξ can improve the subsequent penetration of hydrogen peroxide. To improve permeability, it is necessary to let the alkali penetrate and then leave it for a while. The required standing time varies depending on the tree species, the alkali concentration, and the amount of penetration, but it is short (9).

It is soaked in alkali, then immersed in a solution containing hydrogen peroxide and heated. As a result, hydrogen peroxide penetrates into the wood and reacts with the pigments in the wood. This hydrogen peroxide does not contain alkali and is much more stable than a hydrogen peroxide solution containing alkali t-1. When hydrogen peroxide is applied to wood that has been impregnated with alkali, the hydrogen peroxide decomposes after permeating into the wood. The nine oxygen atoms produced by decomposition react with nearby pigments. When decomposed and the oxygen atoms recombine, a self-decomposition reaction occurs. A bleaching agent that already contains an alkali increases the possibility that the decomposed acid residue of hydrogen peroxide will recombine before it diffuses into the wood and reacts with the pigment. Wood that has been impregnated with alkali beforehand swells to a greater extent than the alkali, making it easier for hydrogen peroxide to diffuse into it. This friend will make you more bleached and dark.

Next, examples of the present invention will be described.

(Example 1) A 1% sodium hydroxide solution (t-100 f/d) was coated on a 1-thick Aius wood rotary lace veneer and left at room temperature overnight. This veneer was immersed in a decolorizing bath containing 2 g of hydrogen peroxide.

The weight ratio of wood and hydrogen peroxide solution was 20 kl.

Heat this solution to 80℃ for □□□ minutes and make a hole. KoO
Take out the veneer, dry it, carve it down to the center, and measure the color of that surface. As a result, -value 86, a*1.0
, b*18. It became Q.

(Example 2) 1% on a rotary lace veneer made of 74x wood and 2cm thick.
Sodium hydroxide solution 200 f/W? Apply at a ratio of 100% and leave it at room temperature overnight. This veneer was decolorized in the same manner as in Example 1. The result is L*89, al*1.0
, b*X7.0.

(Example 3) A 1 m thick rotary lace veneer made of Aius wood was coated with a potassium hydroxide solution tlo (at a ratio of 1/-).
-Leave it for day and night. This veneer was decolorized in the same manner as in Example 1. As a result, L*87.0゜a 1.0, b*1
It was 9.0.

*(i#!Example: 1m thick rotary lace veneer made of ice 9 material on the flow side.
A 5% ammonia aqueous solution M was applied at a rate of 1005'/m' and left to stand day and night. This veneer was bleached in the same way as Example 1. As a result, L*85.0.

* a 2.0, b*2G, 0 and nine.

(Example 5) A rotary lace veneer made of agathis material with a thickness of l + w3,
1% sodium hydroxide solution'fc100 t/rr?
It was applied at a ratio of -1 and then left for day and night. This veneer was decolored in the same manner as in Example 1. the result,? *89.0, aO,5, b*17.0.

(Comparative Example 1) A 1 m rotary lace veneer made of Aius wood was placed in a bleaching solution containing 1 liter of sodium hydroxide and 2% hydrogen peroxide until the weight of the wood and the bleaching solution was 1; □□□. The mixture was heated to 2IIIipH at 80°C. The color was measured in the same manner as in Example 1. the result,? * 86.0, a 3.0, b * 2G, 0 te ara.

(Comparative Example 2) Two rotary lace veneers made of Aius wood were placed in a decolorizing solution containing 1 part sodium hydroxide and 3 parts hydrogen peroxide so that the weight of the wood and the decolorizing solution was 40 liters. , 4 at 80℃
I was so excited. Since the seventh conclusion * *, L 85, a 3.5, b * 22.0.

(Comparative Example 3) A 1 m rotary lace veneer made of Aix wood was placed in a bleaching solution containing 1 liter of potassium hydroxide and 2% hydrogen peroxide, so that the weight of the wood and the bleaching solution was 1:30. was decolorized in the same manner as in Comparative Example 1.

As a result, L*85.0, a*4.0, b*2
It's 1.0.

(Comparative Example 4) A rotary lace veneer made of Aiwath wood was placed in a decolorizing solution containing 0.5% ammonia and 2-hydrogen peroxide so that the weight of the wood and the decolorizing solution was 1:30. was decolorized in the same manner as in Comparative Example 1.

As a result, L 84.0, a*2.5, b*2
At 1.0, * (Comparative Example 5) The Aix material of Comparative Example 1 was replaced with Agatis material, and the rest was bleached in the same manner as Comparative Example 1. 7t, As a result, L 87.0
, a*1.0, b*18.0.

* From the above experimental results, it can be seen that the present invention has a distinct effect.

(Effects of the Invention) In the process of decolorizing wood, the wood is impregnated with an alkaline solution in advance, and then a decolorizing agent solution containing hydrogen peroxide is applied or immersed in the decolorizing agent liquid. (b) Compared to conventional methods, the amount of hydrogen peroxide required can be reduced.

(b) Decolorization time can be shortened.

(c) Decolorization costs can be reduced.

It has the following effects.

Claims (1)

[Claims] A method for decolorizing wood, which involves impregnating the wood with an alkaline solution in advance, and then applying or immersing the wood in a decolorizing liquid containing hydrogen peroxide to decolorize the wood.