JPS61270106A - Manufacture of improved 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 producing modified wood that imparts flame retardancy to wood.

[Background technology]

There are various treatment methods for imparting flame retardancy to wood. When classified based on the flame retardant mechanism, they can be roughly divided into the following types.

(al Coating treatment with inorganic substances (bl Carbonization promotion treatment (C) Treatment to inhibit chain reaction in flaming combustion (d) Treatment to generate nonflammable gas (e)
Treatment for absorbing heat through decomposition and release of crystallized water (f) Treatment for heat insulation using a foam layer;
With the conventional treatment methods classified as mentioned above, it has been difficult to obtain modified wood having sufficiently satisfactory flame retardancy.

[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 producing modified wood that can obtain wood having excellent flame retardancy.

[Disclosure of the invention]

In order to achieve the above objectives, the inventors conducted repeated research and added ettringite (3CaO・AltOx) to wood.
-3CaSOa .nH,O, n=28 to 32), it was thought that a modified wood having excellent flame retardancy could be obtained. Ettringite is not only nonflammable itself, but also has a lot of water of crystallization and releases all of the water of crystallization at 110°C, so the effects of the treatment methods (a) and (e) above can be expected. It is from. Furthermore, since it is insoluble in water, there is no risk of leaching out of the wood. The treatment methods for (a) and (el) will be explained in detail below.By the treatment method (a), even if the material is combustible, it will be difficult to For example, in the conventionally known wood cement board, the ratio of combustible wood to non-combustible cement is approximately 1:1.
It is molded into a plate shape with a blending ratio of , and is recognized as a quasi-nonflammable material by JIS. (In the treatment method for el, decomposition refers to the release of water by hydroxide, etc., according to the following formula, for example.

Ca (OH) z Ca O+ Hz 0
2 A I (OH) :l → A 1 z 0
3 + 3 Hz O This reaction is endothermic. Furthermore, the reaction of releasing water of crystallization is also an endothermic reaction, and the flame retardance of the flammable material can be improved by combining a flammable material with a nonflammable inorganic substance that can undergo such a reaction.

However, it has been found that even if ettringite is directly dispersed in water and wood is soaked in the dispersed water, it is difficult for ettringite to penetrate into the wood. This is because the pit membrane pores in the cell wall pores, which are the narrowest passages during impregnation into wood, are very small with a diameter of about 0.1 μm.

Therefore, the inventor conducted further research and came to the conclusion that it is difficult to impregnate an inorganic substance through these voids unless it is dissolved in a solvent. They discovered that ettringite could be produced by impregnating wood with an aqueous solution of aluminum sulfate and an aqueous solution of calcium halide, and reacting the two in alkaline conditions.
Furthermore, it was found that by such treatment, a large flame retardant effect can be obtained due to the effect of coating with a nonflammable inorganic substance and the heat absorption effect due to the release of crystallized water, and this invention has now been completed.

Therefore, the gist of the present invention is to impregnate wood with an aqueous aluminum sulfate solution and an aqueous calcium halide solution, maintain the interior of the wood alkaline, and then cure the wood. The present invention will be explained in detail below.

Examples of the wood used in this invention include raw wood logs, sawn timber products, sliced veneer 9 plywood, etc., and the type thereof is not particularly limited.

Aluminum sulfate (Alt(504)
) 3) Impregnate the wood with an aqueous solution and an aqueous calcium halide solution, and react the aluminum sulfate and calcium halide in alkaline conditions to generate ettringite in the wood.

Calcium chloride (CaC12) is usually used as the calcium halide, but calcium bromide, calcium iodide, etc. may also be used. When producing ettringite by directly mixing an aqueous aluminum sulfate solution and an aqueous calcium halide solution, it is usually preferable to use aluminum sulfate and calcium halide in a molar ratio of 1:6, so as in this invention, Even when performing two-stage treatment of wood with an aluminum sulfate aqueous solution and a calcium halide aqueous solution, it is preferable that the molar concentration ratio of the rainwater solution is 1:6 (aluminum sulfate aqueous solution to calcium halide aqueous solution).

Since the ettringite production reaction proceeds in alkaline conditions,
It is necessary to keep the reaction system alkaline.

Therefore, the aluminum sulfate aqueous solution is usually made alkaline with sodium hydroxide or the like. and,
Aluminum in the aluminum sulfate aqueous solution is dissolved in the form of aluminate ions so that the reaction with the calcium halide aqueous solution occurs on the alkaline side. pH
is preferably 10 or more, more preferably around 11.

The wood is impregnated with an aqueous solution as a treatment liquid by immersion or the like. In the case of air-dried or bone-dry wood, it takes a considerable amount of time to impregnate it with an aqueous solution to saturation. Therefore, if the wood is saturated with water in advance by underwater wood storage, steaming, impregnation under reduced pressure, impregnation under pressure, etc., and then the wood is brought into contact with an aqueous solution by dipping, etc., aluminum sulfate as a treatment agent can be used. The calcium halides and calcium halides diffuse quickly through the water in the wood, resulting in shorter soaking times.

After the wood is impregnated with the aluminum sulfate aqueous solution and the calcium halide aqueous solution as described above, the wood is heated and cured. During curing, the reaction between aluminum sulfate and calcium halide progresses to form ettringite (
A precipitate) is formed. The curing is preferably carried out at a temperature of 40°C or higher for 3 hours or more. For example, cure at 70°C for about 5 hours.

The modified wood thus obtained has excellent flame retardancy. Moreover, it has excellent dimensional stability.

Next, examples will be described.

(Example 1) The following wood to be treated and a treatment liquid were used.

Treated wood: cedar 1fi thick veneer Adjust moisture content to 200% before treatment Treatment solution A: IM aluminum sulfate aqueous solution adjusted to pH 12 with sodium hydroxide Treatment solution B: 6M calcium chloride aqueous solution Treated wood to 70% It was immersed in treatment solution A at ℃ for 6 hours. Thereafter, the wood was immersed in treatment solution B without drying and left at 70°C for 12 hours to obtain modified wood with a weight increase rate of 59%. It was found to be flammable, especially highly self-extinguishing. Further, as a result of examining the dimensional stability, it was found that the anti-shrinkage ability (ASE) was 62%, indicating that the dimensional stability was excellent. Further, as a result of examining the product produced in the wood by the above treatment by X-ray diffraction, it was confirmed that the product was ettringite.

(Example 2) The following materials were used as the wood to be treated and the treatment liquid.

Wood to be treated: Treatment solution A for air-drying 3mm thick cedar veneer
: 1M aluminum sulfate aqueous solution adjusted to pH 12 with sodium hydroxide Treatment liquid B: 6M calcium chloride aqueous solution The wood to be treated was immersed in treatment liquid A at 95°C for 12 hours. After that, the wood was immersed in treatment solution B without drying, and heated to 70℃ for 12 hours.
I left it for a while. Through the above treatment, modified wood with a weight increase rate of 42% was obtained, and this modified wood was found to have a high degree of flame retardancy, particularly a high degree of self-extinguishing property. In addition, as a result of investigating the dimensional stability, the anti-shrinkage ability (ASE) was 4.
It was also found that the dimensional stability was excellent.

(Example 3) The following materials were used as the wood to be treated and the treatment liquid.

Wood to be treated: Cedar 1fl thick veneer Treatment liquid A: 6M calcium chloride aqueous solution Treatment liquid B: 1
pH 1 of M aluminum sulfate aqueous solution with sodium hydroxide
The wood to be treated was immersed in treatment solution A at 70° C. for 6 hours. After that, the wood is immersed in treatment liquid B without drying, and 7
It was left at 0°C for 12 hours. Through the above treatment, a modified wood with a weight increase rate of 32% was obtained, and this modified wood was found to have a high degree of flame retardancy, particularly a high degree of self-extinguishing property.

In addition, as a result of investigating dimensional stability, anti-shrinkage ability (AS
E) was 24%, indicating excellent dimensional stability.

〔Effect of the invention〕

The method for producing modified wood according to the present invention involves impregnating the wood with an aqueous aluminum sulfate solution and an aqueous calcium halide solution, keeping the interior of the wood alkaline, and then curing the wood. A modified wood is obtained which has excellent flame retardancy and also has very good dimensional stability.

Claims (1)

[Scope of Claims] (1) A method for producing modified wood, in which wood is impregnated with an aqueous aluminum sulfate solution and an aqueous calcium halide solution, and the interior of the wood is kept alkaline, and then the wood is cured. (2) The method for producing modified wood according to claim 1, wherein the calcium halide is calcium chloride. (3) The modification according to claim 1 or 2, wherein the aluminum sulfate aqueous solution is alkaline. Wood manufacturing method. (4) The method for producing modified wood according to claim 3, wherein the aluminum sulfate aqueous solution has a pH of 10 or more. (5) The method for producing modified wood according to any one of claims 1 to 4, wherein curing is performed at 40° C. or higher for 3 hours or more.