JPS6132704A - Method of decoloring woody material - 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 materials.

[Background technology]

In the present invention, wood materials include wood, veneer, insulation,
It is a material that includes wood powder, wood powder, and processed materials.

When decolorizing the above-mentioned wood materials with a hydrogen peroxide solution (hereinafter referred to as H2O2), the conventional methods include applying H, O, or narcalized H2O2 and leaving it for a while.
Previously, decolorization was done using an immersion method.

The disadvantage of these is that there is a large loss of H and O.

Also, the decolorizing effect is unsatisfactory in both decolorizing power and uniformity.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a method for decolorizing wood materials that makes it possible to efficiently decolorize wood materials.

[Disclosure of the invention]

When alkali is added to H2O2 and impregnated into wood materials and left at room temperature, penetration into the wood is slow, and H2O2
Activation is also small due to the low temperature. Therefore, the bleaching effect becomes smaller.

Therefore, by impregnating with (H, O, ①alkaline solution) and then heating and curing it, the activation of H2O2 is greatly increased, and the penetration of the solution progresses, and the decolorization progresses to the inside of the wood material.

The curing conditions at this time are not limited, but the higher the temperature, the faster the reaction. In addition, in high humidity conditions, it will not dry out and the liquid will penetrate.
It also has a great bleaching effect. Type of alkali used, concentration Hz
Ox 111 degrees is not limited, but usually NaOH, KO
H, Nc2C03, LiOH, etc. are used, and the mixed pH value with H2O2 is adjusted to around 7 to 10.

It is usually used at an alkali concentration of about 1 to 4%.

Further, if sodium silicate or MgSO4 is added to the H2O2 liquid, the decolorizing effect will be further improved. Usually, sodium silicate is used at about 1 to 5% and MgSO40.5 to 2%.

In addition to this * Impregnation with an aqueous solution of a reducing agent before H2O2 treatment has a great effect. The type and concentration of the reducing agent used and the amount of impregnation are not limited.

Na BH4, hydrazine, 5iNa sulfite solution, Na% Rongalite dithionite, oxalic acid, etc. are used.

Furthermore, it is better to perform curing even after impregnating with a reducing agent. The conditions at this time are not limited either, but it is often better to keep it at room temperature for a long time.

Usually, the curing conditions are 15 to 30'' C190% or higher and curing for 12 hours or more at a reducing agent concentration of 1 to 8%, an impregnation amount of 5O-150V.

<Example ■> To decolorize a 1.5 m thick agathis veneer, apply a solution containing 1% H2O2 and 1% NaOH using a sponge roll coater at a rate of about 150 PJ, and then heat at 60°C in 95% RH for 4 hours.
It was cured.

<Example ■> In Example ■, H2O, 2096, NaOH 1%, 3
It was impregnated with a 3% solution of sodium silicate.

<Example> In Example 2, 20% H2O2, 1% NaOH, M
A solution of gSO40.8X was impregnated.

<Example ■> As a pretreatment for Example ■, 15% of NaBH40.8%
0W was applied.

<Example ■> After Example ■, 6 H was added in an atmosphere of 95%
After curing, add 20% H2O, 1% NaOH
Impregnated with.

Immediately after each treatment, the specimens were taken out, frozen cut at the center of the thickness, and measured for color. For reference, samples that were left at room temperature after coating with H, O, and liquid were also measured.

(2) In decolorization by impregnation with a mixed solution of H2O2 and alkali, heat curing improved decolorization and permeability compared to the conventional method of leaving the product at room temperature.

■ Alkaline impregnation → H20, the amount of carbon dioxide is reduced compared to the impregnation process.

Claims (6)

[Claims] (1) A method for decolorizing a wood material, which is characterized by impregnating the wood material with a mixture of hydrogen peroxide and an alkali, and then heating and curing the material. (2) A method for decolorizing a wood material according to claim 1, wherein the curing is performed by leaving the material at high humidity. (3) A method for decolorizing wood materials according to claim 1 or 2, wherein sodium silicate is mixed into the decolorizing solution. (4) The method for decolorizing wood materials according to any one of claims 1, 2, and 3, wherein magnesium sulfate is mixed in the decolorizing solution. (5) Claim 1, characterized in that the wood material is impregnated with a reducing agent as a pretreatment for decolorization with hydrogen peroxide.
A method for decolorizing a wood material according to paragraph 2, paragraph 3, or paragraph 4. (6) Claims 1, 2, 3, 4, or 5, in which curing is performed after impregnation with a reducing agent as a pretreatment.
Method for decolorizing wood materials as described in Section.