EP1043131A1

EP1043131A1 - Bamboo board and method of producing the same

Info

Publication number: EP1043131A1
Application number: EP99302526A
Authority: EP
Inventors: Yi-Ho Ko
Original assignee: KO YI HO
Current assignee: KO YI HO
Priority date: 1999-03-31
Filing date: 1999-03-31
Publication date: 2000-10-11

Abstract

A process for making a bamboo board includes the steps of obtaining thin bamboo chips (21) by planing bamboo stems along the direction of the orientation of bamboo fibers, drying the bamboo chips to remove water so that the water content in the bamboo chips is reduced to 6%-10% by weight, mixing the dried bamboo chips with at least one additive selected from the group consisting of a water-proofing agent and a fire-retarding agent, blending the mixture of the bamboo chips and the additive with a binder so as to bind the bamboo chips, forming the bound bamboo chips into a board under pressure and temperature, and covering the surfaces of the board with facing sheets.

Description

This invention relates to a method of making a board, and more particularly to a method of a board from bamboo.
Wood has been an indispensible material for constructing buildings and making furniture articles. It is increasingly difficult to obtain resources of wood because trees have to be cultivated over several years to produce wood, while the rate of wood consumption has exceeded that of the wood production due to the large demand for wood. On the other hand, the gradual decrease in the resources of trees all over the world has seriously affected the environment and global weather conditions. In many wood exporting countries, regulations are provided by governments to limit the amount of trees cut out of forests. The limited supply of wood has resulted in a significant increase in wood prices. It is therefore desirable to make use of bamboo, which is more easily available than wood, in making furniture articles.
An object of the invention is to provide a process for making a board or the like from bamboo in place of wood.
According to the invention, a process for making a board comprises:
(a) obtaining thin bamboo chips by planing bamboo along the orientation of bamboo fibers;
(b) drying the bamboo chips to remove water so that the water content in the bamboo chips is reduced to 6%-10% by weight;
(c) mixing the dried bamboo chips with at least one additive selected from the group consisting of a water-proofing agent and a fire-retarding agent;
(d) blending the mixture of the bamboo chips and the additive with a binder to bind the bamboo chips;
(e) forming the bound bamboo chips into a board under pressure and temperature; and
(f) covering the surfaces of the board with facing sheets.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawing, of which:
Figure 1 is a schematic view which illustrates a preferred embodiment of the process according to the present invention; and
Figure 2 is a view showing a portion of a bamboo board produced by the present invention.
As shown in Figure 1, a preferred embodiment of a process of the present invention comprises several steps for processing and treating bamboo so as to make a furniture board. The first step of the process is a preparation step in which bamboo leaves and branches are removed from bamboo stems, and the stems are cut into sections 20 of suitable length. The sections 20 are then fed into a planing machine 3 via a conveyor 30 so that the sections 20 are planed and formed into thin bamboo chips 21. In order to maintain the fiber structure of bamboo, planing is done along the direction of the orientation of bamboo fibers. During the planing operation, sections 20 are clamped at their ends. Such clamped ends are not planed and thus are sent to a grinding machine (not shown) for disintegration. The resulting ground pieces can be mixed with the thin bamboo chips 21 and then sent to a next processing station. Alternatively, the ground pieces can be individually sent to the next processing station.
At the next processing station, there is a drying machine 4 for drying the bamboo chips 21 which are fed thereinto by a conveyor 31. The water content in the bamboo segments 21 is reduced to 6-10% by weight in the drying machine 4. After drying, a sulfurization process is carried out to treat the bamboo chips 21. The dried bamboo chips 21 are transferred by the conveyor 31 into a storing tank 5 which has a vibration motor 51. The bamboo chips 21 from the storing tank 5 are then fed into a mixing tank 6 through a flow measuring device 52, and the rate of feeding of the bamboo chips 21 is controlled by the vibration of the storing tank 5.
Additives, such as a preservating agent, a water-proofing agent, and a fire retarding agent, are dosed separately from tanks 53, 54 and 55 into the mixing tank 6 via flow measuring meters 531, 532 and 533. The total amount of the additives used is about 3% -12% by weight based on the weight of bamboo chips 21. The preservating agent may be phenol, pentacholoro sodium phenolate, or other suitable preservating agents. The fire-retarding agent may be a composition which contains zinc chloride, sodium chromate, boric acid and ammonium sulfate. The water-proofing agent may be paraffin and other moisture impervious coating materials.
The bamboo chips 21 are treated by the additives added to the mixing tank 6, which is provided with an agitating unit 61 and are subsequently discharged from the bottom of the mixing tank 6 through a flow measuring meter 62 into a chip binding tank 7. In the chip binding tank 7, which is provided with an agitating unit 73, the treated bamboo chips 21 are blended with a binder resin fed from a binder supply unit 71 through a meter 711. Preferably, for reinforcing purposes, reinforcing fibers are fed from a tank 72 via a control unit 721 to the bamboo chips 21 during the blending operation in the chip-binding tank 7. The reinforcing fibers used in this embodiment are those obtained from plants. Examples of such fibers are fibers of jute and coconut shells. The binder used for bonding the bamboo chips is preferably a thermosetting resin which may be a urea resin or a phenolic resin. The weight ratio of the binder to the bamboo chips is preferably 1:8 to 2:10. The weight percent of the binder is less than 30%. Apart from the above-mentioned thermosetting resin, polyvinyl acetate may also be used as a binder for the bamboo chips 21.
The bamboo chips 21 bonded together by the binder resin are discharged from the bottom of the chip binding tank 7 through a conveying pipe 70 to a forming machine 8, where the resin bound bamboo chips 21 are formed into a board 22 under pressure and temperature. The board 22 is conveyed by a belt conveyor 81 to a next station.
At the next station, the board 22 passes between rollers 92 of a calendering machine 9 while facing sheets 91 are fed between the rollers 92. The board 22 therefore has its two opposite faces bonded adhesively with the facing sheets 91. Finally, the board 22 is cut into board parts 23 of predetermined size by a cutting machine 10.
As shown in Figure 2, the board part 23 produced by the process of the present invention comprises two facing sheets 91 which cover two opposite surfaces of the board 22. The facing sheets 91 are preferably made of wood, PVC or melamine.

Claims

A process for making a board, comprising:

(a) obtaining thin bamboo chips by planing bamboo stems along the direction of the orientation of bamboo fibers;

(b) drying the bamboo chips to remove water so that the water content in the bamboo chips is reduced to 6%-10% by weight;

(c) mixing the dried bamboo chips with at least one additive selected from the group consisting of a water-proofing agent and a fire-retarding agent;

(d) blending the mixture of the bamboo chips and the additive with a binder so as to bind the bamboo chips;

(e) forming the bound bamboo chips into a board under pressure and temperature; and

(f) covering the surfaces of the board with facing sheets.
The process as claimed in Claim 1, wherein the waterproofing agent is paraffin.
The process as claimed in Claim 1, wherein the fire-retarding agent contains zinc chloride, sodium chromate, boric acid, and ammonium sulfate.
The process as claimed in Claim 1, wherein the facing sheets are made from a material selected from the group consisting of wood, polyvinylchloride, and melamine.
The process as claimed in Claim 1, further comprising grinding parts of the bamboo stems which are not subjected to planing.
The process as claimed in Claim 1, further comprising, after step (b), sulfurizing the dried bamboo chips.
The process as claimed in Claim 1, wherein the additive used in step (c) further comprises a preservative to be added to the bamboo chips, the preservative being selected from the group consisting of phenol and pentacholoro sodium phenolate.
The process as claimed in Claim 7, wherein the total amount of the additives used in step (c) is about 3% - 12% by weight based on the weight of the bamboo chips.
The process as claimed in Claim 1, wherein step (d) further comprises adding a reinforcing fiber to the bamboo chips, the reinforcing fiber being selected from the group consisting of jute fibers and coconut shell fibers.
The process as claimed in Claim 1, wherein the weight ratio of the binder to the bamboo chips used in step (d) is about 1:8 to 2:10.
The process as claimed in Claim 1, wherein the binder is a thermosetting resin selected from a urea resin and a phenolic resin.
The process as claimed in Claim 1, wherein the binder is polyvinyl acetate.
A bamboo board produced according to the method of Claim 1, comprising a board body made from a mixture of thin bamboo chips and a binder, the thin bamboo chips being obtained by planing bamboo stems along the direction of the orientation of bamboo fibers, the board body having two opposite surfaces, and facing sheets covering the surfaces of the board body.
The bamboo board as claimed in claim 13, wherein the mixture further comprises a suitable amount of fibers obtained from plants.
The bamboo board as claimed in Claim 14, wherein the weight ratio of the binder and the bamboo chips is about 1:8 - 2:10.