Production method of bamboo board

Abstract

The invention relates to the field of bamboo processing, and particularly discloses a bamboo board production method which comprises the steps that S1, bamboo processing waste is dried, smashed and then sieved, and smashed bamboo particles are obtained; s2, the crushed bamboo particles are taken and added into a bamboo adhesive, gypsum powder and water to be evenly mixed, and then the mixture is put into a mold; and S3, the mold is put into a carbonization furnace to be carbonized, pressing is conducted immediately after carbonization is finished, and the high-quality plate is obtained. The bamboo waste comprises leftover materials, leftovers and bamboo tips left in the processing process of bamboo products. The method disclosed by the invention is simple to operate, the used raw materials are low in price, and the method is suitable for process production and has popularization prospects. The bamboo board prepared by the invention is compact in structure, high in strength, bright in color and low in formaldehyde content, and is a bamboo artificial board with extremely high quality.

Description

Technical Field

[0001] The invention relates to the field of bamboo processing, in particular to a method for producing a bamboo board. Background Art

[0002] Bamboo board is made of processed and fine bamboo pieces glued and pressed. Bamboo board production usually uses 4-6 years old large diameter bamboo, which is processed by sawing, slicing, rough planing, high temperature cooking, high pressure carbonization, drying, fine planing, color selection, embryo pressing, sanding and other dozens of processes. It has excellent physical properties and has the advantages of small water absorption and expansion coefficient, no cracking, no deformation, etc. In the process of bamboo board processing, scraps, scraps, bamboo shoots and other wastes will be generated. Most of these wastes cannot be effectively utilized and are difficult to handle. These wastes are either used as fuel or discarded everywhere, which not only wastes resources but also forms new pollution.

[0003] Molded board is a kind of board made of wood fiber, straw, reed, etc., which is made by hot pressing and gluing with adhesive. For bamboo particleboard, urea-formaldehyde resin is generally used as the adhesive. Urea-formaldehyde resin is a thermosetting adhesive with low price. It is colorless and transparent with high bonding strength, and is widely used in bamboo and wood products. However, it has a fatal flaw, that is, it releases a large amount of formaldehyde during the re-heat setting process. If the material is not treated to remove formaldehyde, it is difficult for bamboo particleboard to meet the national regulations on the formaldehyde content of artificial boards.

[0004] For artificial boards produced from urea-formaldehyde resin, people usually adopt the method of modifying urea-formaldehyde resin adhesive to solve the problem of formaldehyde release during manufacturing and use, such as "Li Zhi, Du Guanben, Ran Xin, Yang Hongxing, Zhou Xiaojian, Yang Long. Gelatin-modified urea-formaldehyde resin [J]. Journal of Northwest Forestry University, 2023, 38(01): 218-223+246." discloses a urea-formaldehyde resin modified with gelatin, which can reduce the curing temperature of the resin and reduce the formaldehyde release. In addition, CN110065129A also discloses a method of using ultra-high pressure to press particleboard to reduce the amount of adhesive, thereby obtaining a bamboo board with low formaldehyde content.

[0005] However, for the above methods, whether it is resin modification, ultra-high pressure equipment or long-term placement to disperse formaldehyde, the cost is increased from raw materials, equipment, storage and other aspects, the economic benefit is low, and it is not conducive to industrialization. Therefore, the present invention is committed to providing a method for preparing low-formaldehyde bamboo particleboard with simple preparation process and low cost. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for producing high-quality boards using bamboo processing waste, so as to at least achieve simple preparation process, low industrial cost and low formaldehyde content in the prepared boards.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The method for producing high-quality boards using bamboo processing waste comprises the following steps:

[0009] S1: drying, crushing and sieving bamboo processing waste to obtain bamboo granules;

[0010] S2: Take the bamboo granules, add bamboo adhesive, gypsum powder and water, mix well, and then put them into the mold;

[0011] S3: placing the mold into a carbonization furnace for carbonization, and pressing immediately after the carbonization is completed to obtain the bamboo board;

[0012] The bamboo waste includes leftovers, scraps and bamboo tips remaining in the processing of bamboo products.

[0013] Furthermore, in step S1, the moisture content of the dried bamboo processing waste is 15-20%.

[0014] Furthermore, in step S1, the particle size of the chopped bamboo particles is less than 0.4 mm.

[0015] Furthermore, in step S2, the bamboo adhesive includes urea-formaldehyde resin and modified products thereof.

[0016] Preferably, the modified material includes gelatin modified urea-formaldehyde resin, propyl benzoate modified urea-formaldehyde resin or any modified urea-formaldehyde resin having the performance of reducing formaldehyde content. Please make it clear that the present invention uses unmodified urea-formaldehyde resin to make the formaldehyde content of the board meet the E1 level limit standard, but if combined with modified urea-formaldehyde resin, the formaldehyde content can be further reduced.

[0017] Urea-formaldehyde resin is a thermosetting resin with a curing temperature of 130-160°C, which is close to the carbonization temperature of bamboo. Therefore, the method directly combines the carbonization step of bamboo with the curing step of adhesive, and simultaneously performs carbonization and product shaping in one step, thereby reducing the process steps.

[0018] Furthermore, in step S2, the weight ratio of the crushed bamboo particles, the bamboo adhesive and the gypsum powder is 100:8-12:4-6:4-6.

[0019] Gypsum powder is a caulking agent commonly used for caulking of ceramic tiles. It is a colorless crystalline powder with low price. Adding a small amount of gypsum powder in the present method, on the one hand, plays a role of caulking. After the water evaporates in the carbonization step, it will fill the tiny gaps between the bamboo particles, making the board more compact. The gypsum is colorless or pale white and will not change the appearance color of the bamboo board. On the other hand, the main chemical component of gypsum is calcium sulfate, which can react with formaldehyde. Therefore, the gypsum powder can also absorb and neutralize the formaldehyde generated when the urea-formaldehyde resin is cured at high temperature, so that the formaldehyde content of the board is reduced.

[0020] Furthermore, in step S3, the carbonization temperature is 150-160°C.

[0021] Furthermore, in step S3, the carbonization time is 0.8-1.2h.

[0022] Carbonization is a common bamboo pretreatment process, which uses high temperature to make bamboo lose a lot of water, decompose and denature sugar, protein and other substances in bamboo, so that bamboo can be insect-proof and moth-proof, and the color of bamboo after carbonization will become more shiny and beautiful. The present invention combines cementation curing, caulking and formaldehyde absorption in the carbonization process, so that multiple steps can be completed in one step, reducing product production cycle and industrial cost.

[0023] Furthermore, in step S3, the hot pressing pressure of the pressing is 1.5-2.5 MPa.

[0024] Another object of the present invention is to provide a bamboo board produced by the above production method.

[0025] The beneficial effects of the present invention are:

[0026] The method of the invention is simple to operate, the raw materials used are all low-priced, suitable for process production, and has a promotion prospect. The bamboo board prepared by the invention has a dense structure, high strength, bright color, and low formaldehyde content, and is a high-quality bamboo artificial board. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described in detail below, but the protection scope of the present invention is not limited to the following.

[0028] Example 1

[0029] A high-quality bamboo board is prepared, and the specific method is as follows:

[0030] Collect the remaining scraps in the preparation process of bamboo (bamboo) plywood, lay them flat in the sun, put them into a crusher for crushing after the surface of the bamboo scraps is basically dry (the moisture content is about 15-20%), and then pass through a 40-mesh sieve. Add water to the sieved broken bamboo particles, urea-formaldehyde resin (purchased from Chengdu Fangzheng Chemical Co., Ltd.), and gypsum powder (purchased from Mianzhu Yijia Technology Co., Ltd.) to mix them in a weight ratio of 100:10:5:5, and put them into a mold after mixing. At this time, the mold is put into the mold for preliminary shaping. Pay attention to the material not to fill the mold too full and too tightly. The mold cannot use a fully sealed mold to prevent the possible expansion of the material or the poor discharge of steam during the carbonization process. After carbonization at 160°C for 1h, take out the mold, take out the basically bonded and solidified material, put it into a hot press for pressing, and the hot pressing pressure is 2MPa. After the pressing is completed (about 5min), a high-quality bamboo board is obtained.

[0031] Example 2

[0032] A high-quality bamboo board is prepared, and the specific method is as follows:

[0033] Collect the remaining scraps in the preparation process of bamboo plywood, lay them flat in the sun, put them into a pulverizer for crushing after the surface of the bamboo scraps is basically dry (the moisture content is about 15-20%), and then pass through a 40-mesh sieve. Add water to the sieved broken bamboo particles, urea-formaldehyde resin (purchased from Chengdu Fangzheng Chemical Co., Ltd.), and gypsum powder (purchased from Mianzhu Yijia Technology Co., Ltd.) to mix them in a weight ratio of 100:12:6:6, and put them into a mold after mixing. At this time, the mold is put into the mold for preliminary shaping. Pay attention to the material not to fill the mold too full and too tightly. The mold cannot use a fully sealed mold to prevent the possible expansion of the material or the poor discharge of steam during the carbonization process. After carbonization at 160°C for 1h, take out the mold, take out the basically bonded and solidified material, put it into a hot press for pressing, and the hot pressing pressure is 2MPa. After the pressing is completed (about 5min), a high-quality bamboo board is obtained.

[0034] Example 3

[0035] A high-quality bamboo board is prepared, and the specific method is as follows:

[0036] Collect the remaining scraps in the preparation process of bamboo plywood, lay them flat in the sun, put them into a pulverizer for crushing after the surface of the bamboo scraps is basically dry (the moisture content is about 15-20%), and then pass through a 40-mesh sieve. Add water to the sieved broken bamboo particles, urea-formaldehyde resin (purchased from Chengdu Fangzheng Chemical Co., Ltd.), and gypsum powder (purchased from Mianzhu Yijia Technology Co., Ltd.) to mix them in a weight ratio of 100:8:4:4, and put them into a mold after mixing. At this time, the mold is put into the mold for preliminary shaping. Pay attention to the material not to fill the mold too full and too tightly. The mold cannot use a fully sealed mold to prevent the material expansion or steam discharge that may occur during the carbonization process. After carbonization at 160°C for 1h, take out the mold, take out the basically bonded and solidified material, and put it into a hot press for pressing. The hot pressing pressure is 2MPa. After pressing is completed (about 5min), a high-quality bamboo board is obtained.

[0037] Comparative Example 1

[0038] A bamboo artificial board was prepared, and the specific method was the same as that of Example 1, except that no gypsum powder was added.

[0039] Comparative Example 2

[0040] A bamboo particleboard is prepared by a traditional method, and the specific method is as follows: the scraps left over from the preparation of bamboo (moso bamboo) plywood are exposed to the sun. After the bamboo surface is basically dry (water content 15-20%), it is put into a crusher for crushing, and then passed through a 40-mesh sieve. The sieved broken bamboo particles are put into a carbonization furnace for carbonization at a carbonization temperature of 160°C. 12w% of urea resin (purchased from Chengdu Fangzheng Chemical Co., Ltd.) is added and mixed and stirred evenly, and then put into a mold for hot pressing (2MPa) at 160°C for 5 minutes.

[0041] Experimental Example 1

[0042] The formaldehyde content of the bamboo boards of Examples 1-3 and Comparative Examples 1-2 was tested by referring to the perforation extraction method in GB 18580-2017. 3 The plate was used as a test piece and placed in the flask of the perforated extractor. 600 mL of toluene was added. The piston at the bottom of the extractor was closed. Water was added to the extraction tube and conical flask of the perforated extractor. The cooling circulating water and the electric heating jacket were turned on for heating. The extraction started from the boiling of toluene for 2 hours. The instrument was stopped. At this time, all the formaldehyde was extracted into the water. After taking it out and fixing the volume, the formaldehyde content was measured by a spectrophotometer. The specific data are as follows:

[0043] Formaldehyde content mg / 100g Example 1 7.8 Example 2 7.3 Example 3 8.0 Comparative Example 1 13.2 Comparative Example 2 13.7

[0044] Experimental Example 2

[0045] The elastic modulus of the bamboo boards of Examples 1-3 and Comparative Examples 1-2 was tested in accordance with the national standard GB / T4897-92. The boards with a thickness of 0.8 mm were tested. The test results are as follows:

[0046] Elastic modulus MPa Example 1 47289 Example 2 46955 Example 3 47231 Comparative Example 1 44330 Comparative Example 2 39472

[0047] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for producing a bamboo board, characterized in that: S1: drying, crushing and sieving bamboo processing waste to obtain bamboo granules; S2: Take the bamboo granules, add bamboo adhesive, gypsum powder and water, mix well, and then put them into the mold; S3: placing the mold into a carbonization furnace for carbonization, and pressing immediately after the carbonization is completed to obtain the bamboo board; The bamboo waste includes leftovers, scraps and bamboo tips remaining in the processing of bamboo products.

2. The production method according to claim 1, characterized in that: In step S1, the moisture content of the dried bamboo processing waste is 15-20%.

3. The production method according to claim 1, characterized in that: In step S1, the particle size of the chopped bamboo particles is less than 0.4 mm.

4. The production method according to claim 1, characterized in that: In step S2, the bamboo adhesive includes urea-formaldehyde resin.

5. The production method according to claim 1, characterized in that: In step S2, the weight ratio of the crushed bamboo particles, bamboo adhesive, gypsum powder and water is 100:8-12:4-6:4-6.

6. The production method according to claim 1, characterized in that: In step S3, the carbonization temperature is 150-160°C.

7. The production method according to claim 1, characterized in that: In step S3, the carbonization time is 0.8-1.2h.

8. The production method according to claim 1, characterized in that: In step S3, the hot pressing pressure of the pressing is 1.5-2.5 MPa.

9. A bamboo board produced by the production method according to any one of claims 1 to 8.