GB2292336A

GB2292336A - High strength bamboo plywood and the process for manufacturing the same

Info

Publication number: GB2292336A
Application number: GB9516504A
Authority: GB
Inventors: Fuming Zhu; Jackson Y Yu; Chuande Luo; C M Cheng; Shanxing Zhu; Davia Y L Chen; Dujuan Xing; Jyhping Ren; Helang Huang; B H Hsu
Original assignee: Associated Industries China Inc; Qingdao Jinyuan Co; QINGDAO JINYUAN CO
Current assignee: Associated Industries China Inc; Qingdao Jinyuan Co; QINGDAO JINYUAN CO
Priority date: 1994-08-18
Filing date: 1995-08-11
Publication date: 1996-02-21
Anticipated expiration: 2015-08-11
Also published as: JPH08197507A; GB2292336B; GB9516504D0; KR960007119A

Abstract

The bamboo plywood includes a face board and a bottom board which are respectively a mono-layer bamboo veneer made of bamboo slices with uniform thickness and width, as well as a core board made of at least two said bamboo veneers by orthogonally laminating those mono-layer bamboo veneers, the adjoin sides of the mono-layer bamboo veneers are coated with water proof resin which is mixed with the preservative. The surfaces of the face board and bottom board are also coated with phenol aldehyde coating or the coating for glass fibre reinforced plastic. The said bamboo plywood is made by cutting the raw bamboo material into pieces and then processing into bamboo slices with uniform thickness and width, fixing the bamboo slices as a whole to form the mono-layer bamboo veneer, drying the veneer up to 12 to 18 percent of water content, coating the veneer with the resin and then drying them up to 12 percent of water content, orthogonally laminating the veneers and processing by hot pressing at the temperature between 140 to 170 degrees centigrade under pressure 20 to 40 kg/cm<2>.

Description

High strength Bamboo Plywood and the Process for Manufacturing the Same This invention relates to a high strength plywood, relates more in particular to a bamboo plywood used for the container floor.

In prior art, the container floor is made of hardwood or the multiple plywood of hardwood, so as to meet the high -echnical requirements of mechanical and physical properties.

Because of the long growth period and large quantity use, the supply of said hardwood is increasingly in shortage and tne price is growing up. For the reason set above, to take other raw materials in replacement of hardwood is an urgent need c tne trade.

Currently, several processes are adopted in manufacturing of the bamboo plywood. For instance, a bamboo plywood as disclosed in the Chinese patent application No. CN 100368A is made of mo bamboo (a sort of bamboo like plant growing in @uth China) which is treated by a softening and shaping process. After such a process, a number of cracks are formed in the processed bamboo plywood, consequently, the adhesive strength of the product is highly reduced.Moreover, in saic application, on the one hand, the pieces cut off from raw bamboo materials are not sorted, namely the pieces cut from the same localitation of the raw bamboo materials are not put into same group, as a result, the thickness of the veneers are, due to the arbitrary combination of the bamboo rieces with different quality and density, non uniform; on the other hand, the aforesaid prior art has other drawbacks as lor.

echnological process, high energy expenditure an@ high product costs etc. Another bamboo plywood for container floor as disclosed in Chinese patent application No. CN 2161443Y is made of inner skin of bamboo stem, in the manner that the said inner skin is cut into pieces, coated with resin and dried, the plywood is then formed by orthogonally arranging those pieces layer by layer in a die, exerting pressure on the materials and making the plywood solidified. Such a plywood has the drawbacks as low process automation, complicated technological process, small produce scale, short of quality guaranteed system, non uniform thickness, lack of unity and coherence, big space, great difference between longitudinal and lateral mechanical properties, unsteady quality and low utilization rate of raw materials.

The objective of the present invention is to provide a high strength bamboo plywood which has the merits such as high and steady quality, uniform thickness, small difference between longitudinal and lateral mechanical properties and highly adhesive strength etc.

The objective of the present invention is achieved by following technical resolution: a high strength bamboo plywood includes a face board and a bottom board which are respectively a mono-layer bamboo veneer made of the uniform width and thickness bamboo slices, as well as a core board made of at least two such mono-layer bamboo veneers which are orthogonally laminated; the mutually touched sides of saie mono-layer bamboo veneers are coated with water proof adhesive which is mixed with the preservative. The said slices are processed by cutting the raw bamboo materials into several pieces, splitting the said pieces open into stripes, separating the bamboo stripes into several layers, ad shaping the stripes into straight and flat ones and consequently forming the bamboo slices.By means of a machine, the bamboo slices are arranged side by side and fixed as a whole by nylon thread or by adhesive tape through a hot pressing and solidifying process.

The surfaces of high strength bamboo plywood are coated with phenol aldehyde coating or the coating for glass fibre reinforced plastic. The said water proof adhesive may be chosen among the phenol aldehyde adhesive, chloroprene rubber resin with water proof property, or other water proof resin for common use. The said preservative may include Basileum, Radaleum or Radathiom made by Qingdao Jinyuan Co. or Associated Industries China Inc. The core board can also be made of veneers processed by small bamboo bits or other vegetable fibres. The face board and bottom board can be the single mono-layer bamboo plate or double mono-layer bamboo veneers which are made of the bamboo slices, or can be the single bamboo veneer with high compression ratio.According tD need, one or two hardwood plates with 0.6 to 1.2 mm of thickness may be added to the surfaces of face board and bottom board. The high strength bamboo plywood as disclosed herein can be used as the container floor. As an alternative of the hardwood plate, the plywood provided by this invention enjoys high mechanical and physical properties which full meet the requirements by international standard for the container floor. The plywood provided by this invention a the merits such as rich natural resources, low product cyst, high utilization rate of the raw materials, high process automation, high stability on product quality, unicorn thickness, small space in the structure, and small difference on longitudinal and lateral properties.

The other objectives and merits of this invention will be further described in detail by accompanying with the drawings.

Fig.l is a view showing the pieces of bamboo cut from the raw bamboo material.

Fig.2 is a view showing the bamboo stripe split open from the bamboo piece shown in Fig.l.

Fig.3 is a view showing the bamboo slices with uniform width and thickness after a separating layer by layer process.

Fig.4 is a view showing bamboo slices with uniform thickness and width after a shaping process.

Fig.5 is a view showing how the mono-layer bamboo veneer is formed by the processed bamboo slices.

Fig.6 is a view showing the container floor made of a high strength bamboo plywood as provided by this invention.

Fig.7 is a view showing the structure of the raw bamboo material, in Fig.7 -the outer cuticle of stem 6 -middle portion of stem 7 inner skin of stem.

The high strength plywood as provided by this invention includes face board, bottom board and core board, the process of making these boards is described as following: Cutting the raw bamboo materials into pieces and sorting out the pieces by putting those from same localization of the raw bamboo materials Into the same group; Splitting the said pieces into bamboo stripes by machine; Skinning the outer cuticle of the bamboo stem by machine, Removing the inner skin of the bamboo stem off and then processing the remnant of the bamboo stripes inte uniform thickness and width ones, and further processing these bamboo stripes into straight and flat ones, i.e. bamboo slices; Fixing the bamboo slices side by side as a whole by nylon thread or adhesive tape on the machine, and consequently forming a mono-layer bamboo veneer;; Dewatering the mono-layer bamboo veneer up to 12 to 18 percent of water content by a drier; Coating the mono-layer bamboo veneer with the water proof resin; Drying the said plate once again up to about 12 to 14 percent of water content; Forming the face board and the bottom board by the mono-layer bamboo plate, and forming the core board by orthogonally laminating the said bamboo veneer; Forming the core board by a hot pressing process.

The process for farming the high strength plywood of this invention is further described as following: The raw bamboo materials are cut into pieces according to the actual need; in order to ensure that the bamboo slices are roughly the same in quality, the pieces are sorted out, so that the pieces from the same localization of the raw bamboo materials are put into the same group (please refer to Fig.1). The cut pieces are sequently split open into bamboo stripes with i5mm to 30mm of width by machine (please refer to Fig.2). As it is known by the person skilled in the art that the bamboo stem is composed of three portions, namely outer cuticle, middle portion and inner skin.The outer cuticle of the bamboo enjoys high density, high hardness and other gocd mechanical performances, followed by the middle portion bamboo which takes second place at the mechanical performances, in comparison with the mechanical and physical performances enjoyed by outer cuticle and middle portion of bamboo, the inner skin of bamboo has the lowest density and the lowest strength. For the reason set above, in order to make sure that the bamboo plywood, as a whole, has the uniform mechanical property, the cut bamboo pieces are to be processed by separating the outer cuticle, the middle portion and the inner skin by means of the machine.The outer cuticle of bamboo stem can be used to make handicrafts, the inner skin of the bamboo can be used to make low-quality plywood, the middle portion of bamboo which in comparison with other portions of the bamboo stem has uniform texture can be processed into 1 to 5 mm thickness of bamboo slices (please refer to Fig.3) . Because the sizes and the bamboo joints of the raw bamboo materials are different from one to another, the split bamboo stripes are different. Therefore, the said stripes should be further treated into the slices with uniform width and thickness through a shaping machine (please refer to Fig.4). After being treated by above mentioned shaping process, the bamboo slices are obtained with the thickness, width and degree of straight roughly the same from one to another.The mono-layer bamboo veneer is formed on a special purpose machine by fixing side by side the processed bamboo slices into a mono-layer bamboo veneer with the nylon thread, or with the adhesive tape through a hot pressing and solidifying process (See Fig.5). As the said slices are roughly uniform in thickness, width and degree of straight, the space between the adjoining slices can be reduced within an international allowable framework (not more than 1.5mum). Afterwards, the mono-layer bamboo veneer is to be dried up to 12 to 18 percent of water content, and coated with the adhesive by means of a machine, the adhesive used thereon can be water proof phenol aldehyde adhesive, water proof chloroprene rubber resin, or the common resin with high water proof property; it is perfectible to add in the aforesaid resin, the preservative and insect proof agent, sucn as Basileum, Radaleum or Radathiom which are supplied by Qingdao Jinyuan Co. or Associated Industries China Inc.; wherein the retention rate of phoxim is no less than 0./kg/m3.

The one side of the mono-layer bamboo plate can be coated with 80 to 110 kg/m3 of resin (50% of solid content), or the both sides of the mono-layer bamboo plate can be coated with 110 to 140kg/m 3 of resin if necessary. The mono-layer bamboo plate coated with resin is, afterwards, dried up to 12 to 14 percent of water content. The basic component of this invention, i.e. mono-layer bamboo veneer is formed as described above.

The process for forming the container floor by the monolayer bamboo veneer is further described in accompanying with Fig.6. The container floor is made of the face board 1, bottom board 2 and core board 3, and coated with the water proof adhesive 4 and coating. The said face board 1 and bottom board 2 are respectively single mono-layer bamboo veneer. However, the said face board 1 and bottom board 2 may also be formed by the high compression ratio veneer made of two or more said mono-layer bamboo veneers through a hot pressing process under the pressure 40kg/cm2. The core board 3 is formed by at least two of the mono-layer bamboo veneers laminated orthogonally or instead, by the veneers made of bamboo bits or other vegetable fibre. Ohe adjoin sides of the mono-layer bamboo veneer is coated with the water proof adhesive 4.The face board, the core board and the bottom board are laminated together and then the container floor is formed by hot pressing process under a compression ratio 1:1.5, temperature between 140 te 170 degrees centigrade, pressure between 20kg/cm2 to 40kg/cm2.

In order to ensure the high water proof performance of the container floor, the face board and the bottom board can be coated with phenol and aldehyde resin or resin for glass tore material, or according to actual need, the one or two hardwood veneers with 0.6 to 1.2mm thickness can be added to the outer surfaces of the face board and the bottom board.

The physical and mechanical performances of the bottom of container provided by this invention are measured as followings: water content < 10% specific gravity 0.8 to 0.85 adhesive strength > 2.5 MPa longitudinal bending strength > 80MPa transverse bending strength > 40MPa The said performances listed above are in conformity with the international standard in the trade. In addition, as it is shown by the loading test, the strength of the base-lifting and the strength of the fork-pocket lifting are also in conformity with the international standard in the trade.

Example I.

The container floor of this invention is made of thirteen mono-layer bamboo veneers, wherein the face board and the bottom board are respectively ma of two mono-layer bamboo veneers. The container floor is Pt essed under the following conditions: Hot Pressing Temperature: 150 degrees centigrade Hot Pressing Pressure : 20 kg/cm2 The surfaces of the container floor are coated with phenol and aldehyde resin of 100kg/m3 The technical performances or the container floor are as follows: Density : 0.72 Compression Ratio: 1 : 1.15 Bending strength : 80 MPa in longitude 41 MPa In transverse Elastic Modules : 10100 MPa in longitude 4050 MPa in transverse Example II.

Hot pressing pressure is 32kg/cm2, other conditions are the same as those in Example I. The technical performances of the container floor are as follows: Density : 0.8 Compression Ratio: 1 : 1.25 Bending Strength: 107 MPa in longitude 62 MPa in transverse Elastic Modules : 11500 MPa in longitude 6100 MPa in transverse Example III.

Hot pressing pressure is 40kg/cm2, other conditions are the same as those in Example I. The technical performances of the container floor are as follows: Density : 0.85 Compression Ratio: 1 : 1.5 Bending Strength: 160 MPa in longitude 81 MPa in transverse Elastic Modules : 11700 MPa in longitude 7000 MPa in transverse Example IV.

The cqntainer floor of this invention is made of fifteen mono-layer bamboo veneers, wherein the face board and the bottom board ate respectively made of two mono-layer bamboo veneers. The container floor is processed under the following conditions: Hot Pressing Temperature: 150 degrees Hot Pressing Pressure : 32 kg/cm2 The surfaces of the container floor are coated with 110keg/3 of phenol and aldehyde resin.

The technical performances of the container floor are as follows: Density : 0.85 Compression Ratio: 1 : 1.26 Bending Strength: 109 MPa in longitude 65 MPa in transverse Elastic Modules : 11700 MPa in longitude 6300 MPa in transverse Adhesive Strength: 2.7 MPa Example V.

The container floor of this invention is made of fifteen mono-layer bamboo veneers, wherein, the face board and bottom board are respectively made of two of the mono-layer bamboo veneers. The container floor is processed under the following conditions: Hot Pressing Temperature: 150 degrees centigrade Hot pressing pressure : 32kg/cm2 The two surfaces of the container floor are coated with il0kg/cm3 of phenol and aldehyde resin.

The technical performances of the container flocr are as follows: Density : 0.83 Compression Ratio: 1 : 1.27 Bending Strength: 111 MPa in longitude 67 MPa in transverse Elastic Modules : 12100 MPa in longitude 6500 MPa in transverse Adhesive Strength: 2.9 MPa retention rate of phoxim 0.78kg/cm3

Claims

We claim

1. A high strength bamboo plywood, comprising a face board, a bottom board and a core board, the said face board and bottom board are respectively the mono-layer bamboo veneer which is made of the bamboo slices with uniform thickness and width, the said core board is made of at least mono-layer bamboo veneers by orthogonally laminating said bamboo veneers, the adjoin sides of the said veneers are coated with water proof adhesive; wherein the said bamboo slices are processed by cutting the raw bamboo materials into pieces, sorting out the pieces by putting those pieces cut from same localization of the raw bamboo materials into same group, splitting the bamboo pieces into bamboo stripes, separating the said stripes into three portions, i.e. outer cuticle portIon, inner portion and middle portion, shaping the middle portion of the stripes; the width and the thickness of the bamboo slices are respectively 15 to 30 mm, 1 to 5 mm, the surfaces of the face board and the bottom board are coated with coating.

2. A high strength bamboo plywood as defined in claim 1, wherein the said mono-layer bamboo veneers are made of the said bamboo slices with uniform thickness and width by fixing the slices side by side as a whole through the nylon tread.

3. A high strength bamboo plywood as defined in claim 1, wherein the said mono-layer bamboo veneers is made of the said bamboo slices with uniform thickness and width by fixing the slices side by side as a whole through the adhesive tape.

4. A high strength bamboo plywood as defined in claim wherein the face board and the bottom board are respectively the said mono-layer bamboo veneer, or the mono-layer bamboo veneer and one or two hardwood plates with the thickness between 0.6 to 1.2 mm.

5. A high strength bamboo plywood as defined in clan wherein the face board and the bottom board are respectively made of two mono-layer bamboo veneers, or made of the said mono-layer bamboo veneer and one or two hardwood plates with the thickness between 0.6 to 1.2 mm.

6. A high strength bamboo plywood as defined in claim 1, wherein the face board and the bottom board are respectively the mono-layer bamboo veneer with high compression ratio, or the said mono-layer bamboo veneer and one or two hardwood plates with the thickness between 0.6 to 1.2 mm.

7. A high strength bamboo plywood as defined in claim 1, wherein the surfaces of the face board and the bottom board are coated with phenol aldehyde adhesive.

8. A high strength bamboo plywood as defined in claim 1, wherein the surfaces of the face board and the bottom board are coated with resin.

9. A high strength bamboo plywood as defined in claim 1, wherein the core board is made of bamboo bits.

10. A high strength bamboo plywood as defined in claim 1, wherein the core board is made of vegetable fibre.

11. A high strength bamboo plywood as defined in claim 1, wherein the said water proof adhesive is the phenol aldehyde resin.

12. A high strength bamboo plywood as defined in claim 1, wherein the said water proof adhesive is the chloroprene rubber resin.

13. A high strength bamboo plywood as defined in claim -, wherein the said plywood is used mainly for the container floor.

14. A high strength bamboo plywood as defined in claim -, wherein the water proof adhesive is mixed with the preservative, herein the retention rate of the phoxim is nt less than 0.7kg/m3.

15. A process for manufacturing a high strength bamboo plywood, comprising the processing steps as cutting the raw bamboo materials into pieces; splitting the said pieces into bamboo stripes; drying treatment; forming the mono-layer bamboo veneers; and hot pressing; wherein the bamboo slices are made 15 to 30mm in width and 1 to 5mm in thickness by further processing steps as skinning the outer cuticle of the bamboo stem, removing the inner skin of the bamboo stem off, shaping the slices into flat ones; each bamboo veneer is made of the bamboo slices cut and processed from the same portions of the raw bamboo materials, and is processed by drying treatment, coated with the adhesive; and then is processed once more by drying treatment up to 12% to 14% water content under the temperature of 140 to 170 degrees centIgrade, the said plywood is made by laminating orthogonally the mono-layer bamboo veneers as a whole by hot pressing treatment under the compression ratio of 1:1.15 to 1:1.5 and the pressure of 20kg/cm2.

lo. A process for manufacturing a high strength bamboo plywood as defined in claim 15, wherein the said bamboo slices are made side by side as a whole by means of the adhesive tape or the nylon tread.

;7. .2 process for manufacturing a high strength bamboo plywood as defined in claim 15, wherein the said adhesive is water proof one.

i8. A process for manufacturing a high strength bamboo plywood as defined In claim i7, wherein the said adhesive is mixed with 3.5kg/m3 of preservative, the retention rate of phoxim is more than 0.7kg/m3.

19. A process for manufacturing a high strength bamboo plywood as defined in claim 15, wherein the one side or the mono-layer bamboo veneer is coated with 80 to 100kg/m3 of adhesive.

20. A process for manufacturing a high strength bamboo plywood as defined in claim 1, wherein the two side of the mono-layer bamboo veneer are coated with 110 to 140 kg/m3 of adhesive.

21. A high strength bamboo plywood constructed and arranged sbstantally as described herein with reference to and as illustrated in the accompanying drawings.

22. A process for manufacturing a high strength bamboo plywood substantially as herein described with reference to and as illustrated in the accompanying drawings.