JPS6011309A - 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〕 This invention relates to a method for decolorizing wood.

[Background technology]

Conventionally, there has been a method of decolorizing the wood by applying a hydrogen peroxide solution to the surface of the wood and then curing (or leaving the wood to stand) at a temperature ranging from room temperature to high temperature (for example, 100° C.). Furthermore, in order to enhance the bleaching effect, a so-called steam curing method was developed in which the wood is exposed to steam during curing. This steam curing method has dramatically improved the degree and speed of decolorization of wood, but depending on the wood, there may be cases where a higher degree of decolorization is desired, or
There are cases where it is desired to further increase the speed of decolorization, and its development has been desired.

The decolorizing effect of a hydrogen peroxide solution is caused by the following two types of decomposition of hydrogen peroxide. One is decomposition, which is highly effective in decolorizing wood. Its chemical formula is expressed as Ha Og-〇〇-+ 1'', , , ■, and reductive decolorization is performed by the action of HOO-.Another reason is that the decolorization effect is greater than the decomposition of formula ■. It is a weak decomposition.The chemical formula is H,O,→H,O+ (0)
...It is expressed as ■, and oxidative decolorization takes place due to the action of nascent oxygen (0). Decolorization of wood by hydrogen peroxide is achieved by both of the above two types of decomposition.

However, in the conventional decolorization method, the surface coated with hydrogen peroxide was cured while being exposed to the outside air, so
A large amount of nascent oxygen (0) generated by the decomposition of the formula escapes into the outside air, wasting H2O2 and reducing the decolorizing effect. Moreover, the fact that a large amount of nascent oxygen (0) is constantly escaping from the reaction system where the decomposition of formula (■) is occurring provides an extremely favorable environment for the reaction of formula (■) to proceed in the direction of the arrow. This means that the decomposition reaction of formula 0, which has a strong decolorizing effect, is suppressed, and the decomposition of formula 0, which has a weak decolorizing effect (decomposition of formula Ta. Furthermore, in conventional decolorization methods, hydrogen peroxide itself vaporizes during curing and escapes into the outside air as steam, so hydrogen peroxide is wasted in this sense as well.

In order to improve the decolorization degree and decolorization speed of wood, it is necessary to overcome the above-mentioned problems. [Objective of the Invention] Therefore, from the above-mentioned viewpoint, this invention aims to solve the problem of wasting hydrogen peroxide. The purpose of the present invention is to provide a method for decolorizing wood that suppresses the amount of decolorization, has an excellent degree of decolorization, and shortens decolorization treatment time.

[Disclosure of the invention] In order to achieve the above objectives, the inventor has made extensive studies,
completed this invention.

This invention relates to a method for decolorizing wood in which wood coated with a hydrogen peroxide solution is steam-cured, which is characterized in that the hydrogen peroxide solution is applied to the surface of the wood, and then the applied surface is sealed from the outside air. Its gist is the decolorization method. Hereinafter, an embodiment thereof will be described in detail based on the accompanying drawings.

Fig. 1 is a cross-sectional side view of an example of the hydrogen peroxide solution application step, which is the pre-step of the method of the present invention, and Fig. 2 is a cross-sectional side view of an example of the method of decolorizing wood according to the present invention. 3 and 4 are cross-sectional views showing different embodiments of the method for decolorizing wood according to the present invention. As shown in FIG. 1, the veneer 1 is inserted into a roll coater 2 for double-sided coating, and decolorizing liquids 3 are applied to both the upper and lower surfaces of the veneer 1 while moving in the direction of the arrow. Continuing,
As shown in FIG. 2, steam curing is performed with the veneers 1 stacked so that the surfaces coated with the decolorizing solution overlap. In the figure, 4 is a curing room. In this case, hydrogen peroxide and nascent oxygen are prevented from escaping by closely overlapping the surfaces coated with the decolorizing solution.

Next, other examples of the wood decolorizing liquid according to the present invention will be described. As shown in FIG. 1, the veneer l is inserted into the roll coater 2 for double-sided coating, and the decolorizing liquid 3.3 is applied to both its upper and lower surfaces while moving it in the direction of the arrow. Next, as shown in Figure 3, the veneers 1... are stacked so that the surfaces coated with the decolorizing solution overlap, and the entire stacked veneers 1... are covered with a vinyl sheet, polyethylene sheet, etc. Steam curing is performed while wrapped in the sheet material 5. In the figure, 4 is a curing room. In this way, if the entire stack of veneers is further wrapped with a vinyl sheet, etc., the escape prevention effect will be further enhanced, and the escape prevention effect will also be obtained in that the surface of the topmost veneer will not be exposed to the outside air. This is what happens.

In the method for decolorizing wood according to the present invention, there are no particular restrictions on the steps up to applying the hydrogen peroxide solution. For example, wood coated with alkaline solution may be loaded and cured until the alkaline solution has sufficiently penetrated the wood. Furthermore, there are no particular restrictions on the method or conditions for applying the hydrogen peroxide solution; for example, a spray may be used or the wood may be immersed in the hydrogen peroxide solution. In the example, the hydrogen peroxide solution was applied to both the upper and lower surfaces, but it may be applied to only one side.

In the example, during curing after applying hydrogen peroxide solution,
Although the wood was cured while being exposed to steam, the method is not limited to this, and any curing may be performed in an atmosphere with humidity that does not dry the wood.

There are no special restrictions on the number of timbers loaded during curing. Also,
In the embodiment, the entire stack of veneers was wrapped in a vinyl sheet or the like for curing, but as shown in FIG. 4, one veneer 1 was wrapped in a sheet material 5 such as a vinyl sheet, It is also possible to apply curing to this. In the figure, 6
is a nursing room.

In the method for decolorizing wood according to the present invention, the methods for sealing the wood from the outside air include stacking veneers on top of each other and wrapping the veneers in a vinyl sheet, etc. in the examples, but they are not limited to these methods. Any sealing method that minimizes exposure of the surface to which the hydrogen peroxide solution is applied may be used.

In the method for decolorizing wood according to the present invention, the wood to be treated is a veneer in the embodiment, but it goes without saying that other wood materials can also be treated. However, if the sealing method from outside air is by loading,
Preferably, they are of the same size. This is because the surfaces coated with the hydrogen peroxide solution can completely adhere to each other over the entire surface.

Next, based on the method of decolorizing wood according to the present invention, two examples and a comparative example for each of these examples are given.
The results of measuring the degree of decolorization are shown.

[Example 1] A total of 90 gr/% of a 2% NaOH aqueous solution was applied to both the upper and lower surfaces of a pine veneer (300 mm x 600 mm x 0.8 mm+), and was cured at room temperature for about 10 hours so as not to dry. After that, H2O2 50% aqueous solution meter 1 was placed on both the top and bottom surfaces of the veneer.
00gr/I was applied, 30 sheets were stacked and heated to 100℃.
, 100% R, H, and was cured for about 2 hours in a curing chamber. The degree of decolorization is L''=87.518''=1.0. b
Rice = 19.0.

[Comparative Example 1] After applying the same veneer as in Example 1 up to H20□ aqueous solution application, only one veneer L was placed in the curing chamber 7 under the same conditions as in Example 1, as shown in FIG. It was cured for about 2 hours. The degree of decolorization is L''=84.3, a=0.5, b''=2
It was 3.0.

As seen in the comparison of the degree of decolorization between Example 1 and Comparative Example 1, the degree of decolorization was higher when the veneer was loaded.

[Example 2] A total of 110 gr/rd of a 13% Na01 aqueous solution was applied to the top and bottom surfaces of an agathis veneer measuring 600 mm in length and width and 1.5 mm in thickness, and was cured at room temperature for about 12 hours so as not to dry. Thereafter, a 90gr/rrF aqueous solution of 45% H2O2 was applied to both the top and bottom surfaces of the veneer, and the single sheet was sealed in a polyethylene bag and cured in an atmosphere of 100% R and H at 100° C. for about 2 hours. The degree of decolorization is t, *=
89.0. a * = -3,0+b = 18.0
Met.

[Comparative Example 2] The same veneer as in Example 2 was coated with the H,0□ aqueous solution, and then one of the veneers was left bare and cured for about 2 hours under the same conditions as in Example 2. The degree of decolorization is L'' -84,0+a
"=1-0+b"=23-0.

As seen in the comparison of the degree of decolorization between Example 2 and Comparative Example 2, the degree of decolorization was higher when the veneer was wrapped with an envelop.

〔Effect of the invention〕

As described above, the method for decolorizing wood according to the present invention involves applying a hydrogen peroxide solution to the surface of the wood and then removing the coated surface. Since it is sealed from the outside air, it prevents the nascent oxygen that performs the decolorizing action from escaping into the outside air and prevents hydrogen peroxide from evaporating, reducing the amount of hydrogen peroxide wasted. The efficiency of decolorization increases and the degree of decolorization increases.In addition, the escape of nascent oxygen is prevented, which means that among the two types of decomposition of hydrogen peroxide, the decomposition that produces nascent oxygen decreases and the decolorization has a higher decolorization effect. As a result, the skin coloring effect becomes very efficient and the amount of hydrogen peroxide used for bleaching can be saved.In addition, the bleaching time is shortened due to the improved bleaching efficiency. This will also have the effect of making it possible.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing the hydrogen peroxide application process, Figure 2
The figure is a cross-sectional view of a model of one embodiment of the wood bleaching method according to the present invention, and Figures 3 and 4 are model cross-sectional views of different embodiments of the wood bleaching method of the present invention. FIG. 5 is a cross-sectional view of a conventional method for decolorizing wood as a model. 1... Veneer 3... Decolorizing liquid 4,6.7... Curing room 5... Sheet material agent Patent attorney Takehiko Matsumoto Figure 1 Figure 2

Claims (1)

[Claims] (11) A method for decolorizing wood in which wood coated with a hydrogen peroxide solution is steam-cured, characterized by applying the hydrogen peroxide solution to the surface of the wood and then sealing the coated surface from the outside air. (2) A method for decolorizing wood according to claim 1, wherein the sealing of the surface coated with a hydrogen peroxide solution is carried out by stacking the wood. (3) A method for decolorizing a surface coated with a hydrogen peroxide solution. A method for decolorizing wood according to claim 1 or 2, wherein the sealing is enveloping with an enveloping material. (4) Any of claims 1 to 3, wherein the wood is a veneer. Method for decolorizing wood described in Crab.