JPS6094303A - 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]

BACKGROUND ART Wood with wood grains expressed on its surface has traditionally been used favorably as interior material for houses. However, there are many natural precious woods (
Since it would be very expensive to use, generally, building materials with artificial decorative veneer affixed to the surface are mainly used. Artificial decorative veneers are obtained by degreasing, decolorizing, and dyeing material veneers sliced from cheap lumber from trees, laminating and molding them to form laminated flitches, and slicing this. Decolorization is carried out by applying hydrogen peroxide (hereinafter abbreviated as "H20□") to a veneer of material that has been pretreated such as degreasing, and curing it in a steam atmosphere to decolorize the material. However, in this type of decolorization, if the steam temperature is set to a high temperature, a product with a good degree of decolorization can be obtained in a short time, but if the decolorization is continued as it is, color reversion occurs and the degree of decolorization decreases. There is a problem. For this reason, it is necessary to perform hot water washing immediately after the decolorization is completed, making it difficult and difficult to manage the decolorization process.

Furthermore, in order to avoid such problems, it has been considered to carry out curing decolorization in low-temperature steam.

However, under such conditions, decolorization is carried out slowly and takes a long time, making it easier to manage, but there is a drawback that the decolorization ability is reduced and a high degree of decolorization cannot be obtained.

[Purpose of the invention]

This invention was made in view of the above circumstances, and it makes it possible to leave the product for a long period of time with a high degree of decolorization without returning the color during curing, and to facilitate the management of the decolorization process. The purpose is to

[Disclosure of the invention]

The inventor made extensive studies to achieve the above object. As a result, this invention was completed.

This invention relates to a decolorizing method in which wood is coated with hydrogen peroxide and left to cure in steam, and the wood is cured at a high temperature in the first stage and at a low temperature in the second stage. Its gist is the decolorization method. This will be explained in detail below.

The types of wood used in this invention are:

No matter the size. Furthermore, it does not matter whether or not the wood has been pretreated, but usually wood that has been thoroughly cured with an alkaline solution and degreased is used.

First, an H20□ aqueous solution is applied to the surface of a wood made of sawnboard, veneer, etc., and then the wood is left in a high-temperature steam atmosphere as a first step. The temperature and humidity at this time are 90 to 1
00°C2 relative humidity of 90 to 100% is preferable. In this state, steam curing is performed until the best decolorization is achieved.

There are differences depending on the wood, but usually 30 minutes to 3 hours JV
It becomes bleached at a certain degree. Note that a higher degree of decolorization can be obtained by covering the product with plastic wrap during curing.

Immediately after reaching the highest decolorization state, the zero phase is left in a low-temperature steam atmosphere as a second stage. The temperature and humidity at this time are 5 to 30°C5 relative humidity 90 to 100%
is preferred. If you leave it in this state, you will be able to maintain the best bleached state without color reversion.

It is preferable that the relative humidity during curing and decolorization is always kept high as described above. This is because if drying occurs during curing, H2O2 decomposes and the degree of decolorization decreases, and thin laminates such as veneers may crack. Also, even considering the dyeing process after decolorization, high humidity conditions during curing and decolorization are desirable because dyeing unevenness will be less if the moisture content is high and moisture content is small.

Regarding the lamination of wood, it can be one piece or many pieces,
Although not particularly limited, the thickness of the number of laminated sheets is 20
If the temperature exceeds about cm, the temperature at the center of the laminate becomes difficult to decrease, so the temperature may be shifted to the second-stage low-temperature steam atmosphere as soon as possible, or a heat sink may be appropriately interposed during stacking.

The HtO2 used in this invention is not particularly limited in terms of concentration, coating amount, coating method, etc. Further, other additives may be included in H2O2 within a range that does not impede the effects of the invention.

Examples will be described below.

(Example 1) Thickness: 1.8 mm, length: 1800 mm, width: 300 mm
We prepared 100 pieces of pine veneer for building materials. First, apply Na to the veneer.
A 2% OH aqueous solution was applied to both surfaces of the veneer at a rate of 100 g/rrr, and cured at room temperature for 20 hours or more.

Next, apply 100 g/50% H20□ aqueous solution to both sides of the veneer.
rd, layered, and immediately heated to temperature 1.
In a steam atmosphere at 00℃ and relative humidity of 98% (curing room)
The sample was placed in a refrigerator and cured for 1 hour to decolorize it.

Thereafter, the laminated state was placed in a steam atmosphere (#birthplace) at a temperature of 30° C. and relative humidity of 98%, and left to cure for 7 days. After curing, the veneer was sufficiently bleached without any color reversion. In addition, the veneer had little variation in moisture content (and no cracking was observed because it did not dry out).

(Example 2) On one side of an agathis board with a thickness of 0 mm, a length of 800 mm, and a width of 200 mm, 6% NaOH2.5% aqueous solution was applied.
0 g/m coated and wrapped at room temperature for 20 g/m.
I cured it for more than an hour. Next, remove the wrap and N a O
A 35% H2O2 aqueous solution was applied to both sides of the veneer at a concentration of 60 g/m to one side coated with the H2,5 aqueous solution, and the veneer was wrapped in a steam atmosphere at a temperature of 100°C and a relative humidity of 90% (in a curing room). ) and cured for 1 hour to decolorize. Thereafter, in this state, it was placed in a steam atmosphere (curing room) at a temperature of 30° C. and relative humidity of 90%, and left to cure for 7 days. After curing, the Agatis sawn board did not change color at all (it was sufficiently bleached).

〔Effect of the invention〕

The method for decolorizing wood according to the present invention involves applying H20□ to wood and then leaving it in steam to cure and decolorize it.
Since the first stage of the steam temperature is set to a high temperature and the second stage is set to a low temperature during curing, the wood after bleaching does not return in color during curing as in conventional methods, and has an extremely high degree of bleaching. is obtained. Furthermore, in the second stage low temperature steam atmosphere, it is possible to leave the product for a long period of time, making it very easy to adjust and manage the decolorization process. Moreover, since decolorization involves a combination of coating and curing methods, the cost of materials, energy, etc. can be kept to a minimum, and costs can be reduced.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Claims] (11 In the decolorization method in which hydrogen peroxide is applied to wood and then left to cure in steam, the first stage of the steam temperature is set to a high temperature, and the second stage is set to a low temperature for curing. Characteristic method for decolorizing wood: (2) The method for decolorizing wood according to claim 1, wherein the high steam temperature is 90 to 100°C and the low temperature is 5 to 30°C.