GB2065731A

GB2065731A - Treatment process for utilization of rubber wood

Info

Publication number: GB2065731A
Application number: GB7944288A
Authority: GB
Original assignee: NIPPON PARAWOOD KK
Current assignee: NIPPON PARAWOOD KK
Priority date: 1979-12-21
Filing date: 1979-12-21
Publication date: 1981-07-01
Also published as: MY8600274A; GB2065731B

Abstract

A treatment process for utilization of rubber wood, comprising a pretreatment of boiling the rubber wood in an aqueous solution containing a surface active agent having permeating and dispersing actions, heating the rubber wood so treated under pressure in the presence of an aqueous solution containing a surface active agent and an alkaline latex dissolving agent, dehydrating the wood under reduced pressure, and thereafter drying the rubber wood wherein the surface active agent is an anion type alkyl naphthalene sodium sulfonate.

Description

SPECIFICATION Treatment process for utilization of rubber wood The present invention relates to a treatment process for utilization of rubber wood. The rubber tree (rubber tree after rubber liquid (latex) is derived) is primarily artificially planted in farm lands in various countries such as Malaysia, Thailand, Indonesia, and wood can be easily collected, and is recognized by many experts as the wood having excellent qualities.

The rubber tree belongs to Euphorbiaceae, and its scientific name is Hevea brasiliensis Muell-Arg.

Generally, it is called as rubber tree, Para rubber tree and permeation of rubber latex is normally stopped in 20-25 years after planting, and in many cases, it is burnt down after cutting down.

At present, very small quantity is used as fish box material, chip material, raw material for making charcoal, but the rubber tree is not sufficiently utilized as wood material. The reasons for are as follows:- (1) The rubber wood has weak resistance to discolouring bacteria, and putrefying bacteria, and is subject to corrosion. This means that the rubbery substance is contained in vessels or gap portions of molecular structure of wood, and starch, saccharide, aromatics and the like are also contained in the rubbery substance, and discolouring bacteria putrefying bacteria eat them.

(2) The latex fills the entire molecular structure of the wood, and it permeates naturally on the upper surface even after the lumbering or fabrication is performed.

(3) In case of the rubber wood infester with egg-laying wood borers, and the wood substance is eaten and a complete control of such insects by ordinary insecticide treatment is difficult.

(4) Defects such as bending, torsion, warping, and splitting occur frequently, and a yield after the fabrication is extremely low.

As described in the foregoing, the rubber wood has extremely weak resistance to the discolouring bacteria and putrefying bacteria, and damage by insects are severe, and moreover the latex remains in the wood so that the rubber wood is most difficult to utilize effectively.

Since the rubber trees are planted in concentration on flat farm land according to programs, the cutting down and transportation are easy and besides, the rubber wood can be obtained at extremely low cost as compared with other kinds of woods.

Countries like Thailand and Malaysia are strongly desirous of planned cutting down of the rubber trees and their utilization, and no permit for cutting down is required, and inversely, enterprising is easy as it is encouraged by grant of a subsidy.

Every year, the rubber trees are planted according to program, and with an increased quantity of growth and an enormous accumulated quantity, they can cope with the future quantitative demand sufficiently. Also, the colour of the wood is of graceful white and since wood work of high precision is possible, it is suitable for high class demands such as furniture, household furnishings and the like.

According to the present invention, there is provided a treatment process for utilization of rubber wood, comprising a pretreatment of boiling the rubber wood in an aqueous solution containing a surface active agent having permeating and dispersing actions, heating the rubber wood so treated under pressure in the presence of an aqueous solution containing a surface active agent and an alkaline latex dissolving agent, dehydrating the wood under reduced pressure, and thereafter drying the rubber wood wherein the surface active agent is an anion type alkyl naphthalene sodium sulfonate.

The process of the present invention thus comprises a pretreatment process (a), a main treatment process (b) and a drying process (c).

(a) Pretreatment process: In this process, the rubber wood is placed in boiling tank filled with hot water, and a surface active agent having special permeating and dispersing action is poured to the tank and the wood is boiled for several hours. By this process, the rubber latex filled in the gap portions of the molecular structure of the rubber wood becomes soft and is dissolved and also the molecular structure of the wood becomes soft and is cleaned.

The surface active agent is desired to have strong permeating and dispersing performance to the rubber wood, and has high stability to heat, chemicals, and hard water, and also to have high cleaning action, and it has been discovered that anion type alkylnaphthalene sodium sulfonate is the most effective.

(b) Main treatment process: The rubber wood passing through the pretreatment process is taken out from the boiling tank, and is shifted into an autoclave that can be used to apply and manipulate pressure. In the special autoclave, hot water is added, and the hot water contains the surface active agent and the dissolving agent. The surface active agent can be utilized as in the case of the pretreatment process.

The dissolving agent is preferably of alkaline type in particular case of treating the rubber wood, and as the results of various experiments, alkylamine, ethylbutylamine or soda ash are extremely effective.

In this process, initially, the pressure is applied to the autoclave so that the influence extends into the molecular structure of the rubber wood.

Namely, the hot water in the autoclave can permeate and disperse deeply into the vessels and gap portions of the molecular structure of the rubber wood together with the surface active agent contained in the hot water when the pressure is applied. Simultaneously, as the dissolving agent is contained in the hot water, the rubber latex contained in the molecular structure of the rubber wood is uniformly dissolved. By the dissolving action of the latex, the contained latex is removed, and at the same time, the rubber wood becomes weak alkaline by the alkaline dissolving agent, and the adhesion of bacteria and the proliferation of bacteria can be prevented.

Also, when the pressure is applied to the hot water, the temperature is raised, thus exterminating the insects and eggs of insects.

Also, in the hot water, in order to prevent the damage to the rubber wood by insects, the insecticide can be added.

The sodium borate typically contained in this insecticide can be effective.

After the pressure is applied to the special autoclave, the pressure reduction is manipulated to apply to the autoclave. By this pressure reduction treatment, the low temperature boiling phenomenon occurs inside of the autoclave, and the part of the latex dissolved solution remaining in the molecular structure of the rubber wood is forcedly eliminated to the outside of the molecular structure, and also the latex dissolved solution remaining in the molecular structure is weakly dispersed and spreaded into the molecular structure of the rubber wood.

(c) Drying process: The rubber wood treated by the foregoing treatment is subjected to drying or artificial drying.

Following is a description by way of example only of methods of carrying the invention into effect.

EXAMPLE 1 Rubber wood plank whose thickness was 40 mm, width 90 mm and length 3640 mm was placed in a boiling tank whose depth was 2 m, width and length 4 m respectively, and the treated plank was boiled by hot water of temperature 92-980C containing surface active agent aqueous solution (alkylnaphthalene sodium sulfonate) of 0.3% concentration for 4 hours, and immediately the treated plank was shifted to an autoclave whose diameter was 1.5 m, and length 9 m which was prepared separately, and the treatment was applied to the treated plank in the condition where the pressure was 2 kg/cm2 and temperature was 1200C by the surface active agent of 0.02% concentration, and the aqueous solution similar to the above, ethylbutylamine of 0.2% concentration, aqueous solution of sodium borate of 0.2% concentration for 2 hours, and then the waste solution was discharged. After the solution was drained, reduced pressure dehydration was applied to the treated plank until the moisture content of the treated plank became about + 10% of fiber saturation point (28%-32%), and the treated plank was carried out from the autoclave, and was immediately shifted to the artificial drying chamber and was dried until the moisture content became about 7%. As described in the foregoing, the treated plank having been subjected to the pressure treatment and drying was free from the discolouring bacteria and putrefying bacteria and damage by insects, and also free from the permeation of rubber latex, and the treated plank which was the plank almost without warping and suitable for the furniture material, household furnishings, and wood works was obtained.

EXAMPLE 2 Rubber wood square whose thickness was 70 mm, width 70 mm and length 2000 mm (remark: for furnishing material) was placed into a boiling tank whose depth was 2 m, and width and length 4 m respectively, and the treated square was boiled in a solution consisting of a surface active agent aqueous solution (anion type alkylnaphthalene sodium sulfonate) of 0.5% concentration and hot water of temperature 92980C for 4 hours, and was shifted immediately to an autoclave whose diameter was 1 500 mm, and length 9 m which was separately prepared, and the square was treated in the aqueous solution of naphthalene sodium sulfonate of 0.02% concentration, ethylbutylamine aqueous solution of 0.2% concentration, and aqueous solution of sodium borate of 0.2% concentration in the condition where the pressure was 2 kg/cm2 and temperature was 1 5 C for 3 hours, and then the waste solution was discharged.

After the waste solution was drained, the pressure was reduced until the moisture content of the square became about a fiber saturation point, and boiling phenomenon was caused at 60--1000C to dissolve and remove the latex remaining in the rubber wood or to disperse and spread, and the square was carried from the autoclave and was placed into the artificial drying chamber, and the artificial drying was performed in the temperature condition of 5506 + SOC at moisture content of about 7%.

The rubber wood square treated in the Example 2 was almost free from defects such as torsion, warping, bending, split which are characteristic of the rubber wood, and an increased yield of above 100 was obtained when the rubber wood square was fabricated. Also, the latex ingredient remaining in the molecular structure of the rubber wood was removed or dispersed and spreaded, and also since the entire rubber wood became weak alkali (pH 8.5-9.5) eliminating chances of being erroded by the discolouring bacteria and putrefying bacteria, and producing excellent furniture material with white base whose hardness being improved by 30% was obtained.

Claims

1. A treatment process for utilization of rubber wood, comprising a pretreatment of boiling the rubber wood in an aqueous solution containing a surface active agent having permeating and dispersing actions, heating the rubber wood so treated under pressure in the presence of an aqueous solution containing a surface active agent and an alkaline latex dissolving agent, dehydrating the wood under reduced pressure, and thereafter drying the rubber wood wherein the surface active agent is an anion type alkyl naphthalene sodium sulfonate.

2. A process as claimed in Claim 1 wherein the dissolving agent is alkylamine or ethylamine having alkaline property.

3. A process as claimed in Claim 1 or Claim 2 wherein the dissolving agent is soda ash.

4. A process as claimed in any preceding claim wherein an insecticide is added to the aqueous solution in the main treatment process.

5. A process as claimed in Claim 4 wherein the insecticide is sodium borate.

6. A process as claimed in any preceding claim wherein the aqueous solution in the pretreatment process contains a surface active agent of 0.3% concentration.

7. A process as claimed in any preceding claim wherein the rubber wood is boiled for almost 4 hours with hot water of 900C-980C in the pretreatment process.

8. A process as claimed in Claim 1 and substantially as described in any one of the specific examples hereinbefore set forth.

8. A process as claimed in any preceding claim wherein the pressure is of 2 kg/cm2 and the heating is conducted at 1 200C for 2 hours.

New claims or amendments to claims filed on 16 December 1980.

Superseded claims: All.

New or amended claims.

1. A treatment process for utilization of rubber wood, comprising a pretreatment of boiling the rubber wood in an aqueous solution containing a surface active agent having permeating and dispersing actions, heating the rubber wood so treated under pressure in the presence of an aqueous solution containing a surface active agent and an alkaline latex dissolving agent selected from alkylamine and soda ash, dehydrating the wood under reduced pressure, and thereafter drying the rubber wood wherein the surface active agent is an anion type alkyl naphthalene sodium sulfonate.

2. A process as claimed in Claim 1 wherein the alkylamine is ethylamine.

3. A process as claimed in any preceding claim wherein an insecticide is added to the aqueous solution in the main treatment process.

4. A process as claimed in Claim 3 wherein the insecticide is sodium borate.

5. A process as claimed in any preceding claim wherein the aqueous solution in the pretreatment process contains a surface active agent of 0.3% concentration.

6. A process as claimed in any preceding claim wherein the rubber wood is boiled for almost 4 hours with hot water of 900C-980C in the pretreatment process.

7. A process as claimed in any preceding claim wherein the pressure is of 2 kg/cm2 and the heating is conducted at 1 200C for 2 hours.