Research Status and Trends of Straw-made Artificial Panels at Home and Abroad
2024-04-21 11:08:26
China is a big agricultural country. Every year, crop residues (including wheat straw, straw, sorghum stalk, corn stalk, hemp stalk, cotton stalk, tobacco, etc.) reach more than 1 billion tons, 70% of which are straw and wheat straw. This is a kind of Huge renewable resources. With the advancement of science and technology and the improvement of farmers' living standards, straw is no longer used as a daily fuel for rural areas. How to transform straw into an economic advantage and explore effective ways to comprehensively utilize straw has been receiving increasing attention. According to statistics, the straw currently used only accounts for 30% of the national straw resources, and the remaining large amounts of straw are still incinerated. Straw burning not only causes environmental pollution, but straw burning near airports and highways in summer and autumn has become a major factor in inducing traffic accidents and affecting shipping. Therefore, to solve the comprehensive utilization of crop straws nationwide, the fundamental way out lies in the industrial utilization of crop straws. Among them, straw-made wood-based panels are the most market-developing potential and industrialization prospects in the industrial utilization of straw. The development of straw-based wood-based panels can not only increase straw consumption rate and utilization rate, save wood resources, and protect the ecological environment, but also promote the development of agriculture and rural economy, expand urban and rural employment, and increase farmers' income.
1 Research status of straw-made artificial board
In 1920, Louisiana, Louisiana, established a bagasse production plant. In the 1980s, experimental research on the use of wheat straw for board making began in the northern United States and Canada, and a complete industrial production system has been formed to date. According to reports, the two countries have put into operation and construction of 13 factories, the production capacity of more than 600,000 m3, in addition to 8 companies are raising funds to build factories. In addition, Belgium, Sweden, Portugal, Russia and other countries have carried out such research, and have produced a variety of crop straw artificial wood panels. In the 1980s and 1990s, the factory system for making hard fiberboard and particleboard in bagasse was formed in the south of China. In recent years, the Chinese Academy of Forestry, Central South Forestry College, Northeast Forestry University, Nanjing Materials University and other units have also carried out research and development.
1. 1 straw made artificial board process
The process of crop straw board can be summarized into two kinds, namely integrated process and particle board process.
The integrated process flow is: crop straw → unpacking → removing impurities → heating extrusion → paste protection recycled paper (glass fiber layer can be added) → cutting edge sealing → finished board.
Stram it International (English) is the first company to have this technology. The raw materials are rice and wheat straw. The processing process does not require binders. The thickness of the finished board is 20-80mm. It is mainly used as wall material (such as the English countryside). Building a house) to replace clay bricks (According to statistics, China produces about 500 billion clay bricks per year, which is at the cost of destroying 10,000 hm2 of cultivated land). In the early 1980s, China's new building materials company introduced two straw board processing production lines from the company. Due to the community's doubts about the construction of straw boards, and the technical management of the production line is not timely, the operating conditions are not satisfactory.
The particle board process is: crop straw → unpacking → crushing → removing impurities → grinding → mixing with MDI (binder) → paving → pre-pressing and hot pressing → edge sanding → finished board.
Companies using this process include COMPAK, VALMET, HYMMEN, etc. The products can be used as substitutes for wooden boards in the furniture, flooring, packaging, construction, etc., sheet thickness is 4-35 mm, physical properties of the board. (fire, moisture, heat, mildew), mechanical properties (machined drilling, milling, sawing, etc.) and mechanical properties (MOE, MOR, IB) meet the industry standards of American ANSI-A208 and British BSEN312, and its development prospects broad.
1.2 Structure of straw-made artificial board
According to the structure and use of the product, the straw-based panel products that have been developed and to be developed can be roughly classified into the following three categories:
(1) Straw hard board: refers to straw particle board and straw medium density fiber board with density above 0.659g/cm3, which can replace traditional wood particle board and medium density fiber board for furniture manufacturing, packaging and interior decoration.
(2) Straw lightweight material: refers to low-density, lightweight, heat-insulating lining material made of straw, used as a wall material instead of clay brick. There are three kinds of lightweight walls, including extrusion method, flat pressing method and molding method.
(3) Straw composite material: refers to a sheet made of straw scrap as a filler and composited with inorganic mineral materials or plastics, used as building materials or packaging materials.
In addition, the relevant units have also made encouraging progress in exploring the use of straw to make cement formwork.
1.3 Technical difficulties in making straw-based panels
Since most of the surface of the straw has a substance which is not favorable for gluing, it is difficult to obtain satisfactory bonding strength (especially internal bonding strength) by using a conventional urea-formaldehyde resin or a phenolic resin glue. So far, almost all of the particle board factories that have been built at home and abroad have used isocyanate as an adhesive. This causes two problems: (1) cost problem because the isocyanate price is 8-10 times that of the urea-formaldehyde resin. Although the former is much lower than the latter, the absolute cost is still higher than the latter; (2) Sticky plate problems, such as the direct use of isocyanate adhesives, will cause severe sticking in the hot pressing process.
Crop straw is an annual plant with strong seasonality, loose texture, easy to worm, mildew and rot, and the problems of raw material collection, transportation and storage are outstanding. Although the straw land acquisition price is only a few tens of dollars, the final cost is likely to reach about 200 yuan, which is almost the same as the price of wood raw materials.
So far, straw-based wood-based panels have not been recognized by the majority of users in the market like wooden wood-based panels. Under the same quality conditions, the demand for straw boards is less than that of wood-based panels, and the price of products cannot be high. For wood-based panels, the profit margin will be affected, and you should pay full attention to this when conducting economic analysis.
The one-sided emphasis on the environmental characteristics of straw-based panels, and the blind optimism of its sales is not advisable. And the straw-based wood-based panel enterprises and wooden wood-based panel enterprises of the same scale can only guarantee the similar economic benefits of the two under the premise of very successful operation. A little carelessness will lead to an increase in the cost of straw-based panels and a loss in the factory.
In addition, the problem of the quality standard of straw artificial board, because the raw materials used in the board are different, the wood fiber and the straw fiber are different, the quasi-use objects are different, and the quality standards should be different. After the straw scrap processing, the straw has the problem of thickness and the strength of the sheet. Therefore, the equipment setting of the straw artificial board should also be improved. Different sets of equipment should be developed according to different yields.
2 Management status of straw-made artificial board
The data show that the world has made man-made boards using crop residues for decades. For example, China has introduced the German bagasse medium density fiberboard production line and the British straw board wall production line. However, the production of artificial boards by using the main straw straw and wheat straw as raw materials, especially the industrialized production line, has only a history of about 10 years. . The countries with outstanding achievements in the research of crop straw artificial boards in the world include China, the United States, Canada and other countries. Some straw scraping board factories have been built in North America, such as American Primchar Division and Canadian Isotxir Q Company. In recent years, due to various reasons, some straw-based wood-based panel factories in North America have suffered losses and have closed down again and again, and several companies are still insisting on production.
In China, so far, there are few production lines for straw production with industrial production. Hubei Jingzhou New Composite Materials Co., Ltd. uses the original particleboard production line to transform into a straw slab production line with an annual output of 8000m3. The products are sold to the Hong Kong market, but there is no market in China. Sichuan Guodong Group is about to build a production line that imports most of its equipment from abroad and has an annual output of 50,000 m3 of straw particle board. In addition, there are a number of domestic enterprises that intend to introduce foreign complete production lines, and some have already approved the project.
So far, the crop straw artificial board researched all over the world is straw scraper board, and some papers are written as “medium density fiberboardâ€. According to its process, it is still essentially a particle board. At present, the straw medium density fiberboard produced by high-temperature refining reported at home and abroad is basically a small sample in the laboratory. According to the domestic and foreign straw artificial board construction materials, the current straw artificial board production technology, the same scale straw artificial board enterprises and wooden wood-based board enterprises, only under the premise of very successful operation, can ensure the similar economic benefits. A little carelessness will lead to an increase in the cost of straw-based wood-based panels. The factory will lose money to manufacturers whose equipment is imported and invested in loans. The probability of loss will be higher. Therefore, the enterprises that are interested in investing in straw-based wood-based panel factories are very large. Investment risk.
Based on the above reasons, at present, there are many phenomena such as “laboratory research, less industrialization promotion, more feasibility reports, less actual investment and construction, more support for product public opinion, and less practical application†for straw-based panels. In general, the production of artificial straws at home and abroad is still in its infancy, the product variety needs to be developed, the product performance needs to be improved, the production cost needs to be reduced, the product application needs to be expanded, and the market sales need to be developed.
3 Research trend of straw-made artificial board
According to the crop stalk is an annual plant, seasonal, loose texture, easy to worm, mildew and rot, the production process should use the "waste recycling station" business model, follow the principle of long-term sharing of benefits, raw materials purchase in batches Dispersed storage, centralized transportation, which not only solves the problem of raw material collection, transportation and storage, but also ensures that the price of straw raw materials is much lower than that of wood raw materials. Therefore, this production and operation model needs to be researched and applied.
If the straw-based wood-based panel has all the characteristics and advantages of the dry fiberboard (wood), the appearance is the same as that of the dry fiberboard (wood), and the market is highly integrated, and does not require product promotion and market adaptation, and can be directly like dry fiberboard (wood). Used in furniture, flooring, speakers, television, packaging, construction and other industries. Therefore, the development of straw fiberboard production process is the most promising research in the technology of straw-based wood-based panel, which is also the urgently needed comprehensive utilization technology of straw industrialization.
In addition, the straw activation technology needs to be developed and improved. It is assumed that it can be effectively activated according to the structural characteristics of the straw cells and the characteristics of the chemical components, so that it has a certain self-gluing property, and then a small amount of low formaldehyde is released. The environmentally friendly urea-formaldehyde resin glue ensures product strength. This not only avoids the cost problems and sticking problems caused by the cyanate adhesive, but also ensures that the product cost is much lower than that of similar wood panels.
references
1 Wang Shengzhen, Han Helin, Yu Jianxiong, etc. Development prospects of using artificial crop boards for crop straws. Journal of Agricultural Machinery 12000:122- 123
2 Lan Dongli, Shi Kejun vigorously develops non-wood wood-based panels according to China's national conditions. Produced by the China Forestry Society Wood Industry Branch (19), 2000: 90-92
3 Xinghang wheat straw homogenizing board processing and application prospects Proceedings of the Wood Industry Branch of China Forestry Society (19), 2000: 93-98
4 Huajun, Lu Renshu wheat straw particle board preparation section processing technology research forestry industry, 2000, (2): 20-23
5 Li Yanjun, Gao Jianmin, Zhang Shuangbao, et al. Recent research and development prospects of straw-based panels in China. Building Panels, 2002, (1): 3- 5
6 Jiang Yuanzhou, Xiang Shilong compiled non-wood wood-based panels Beijing: China Forestry Publishing House, 1989
Development Status, Difficulties, Risks and Suggestions for the Development of Crop Straw Artificial Panels in Dingguo in 7 Weeks, 2002, (2): 3-6
1 Research status of straw-made artificial board
In 1920, Louisiana, Louisiana, established a bagasse production plant. In the 1980s, experimental research on the use of wheat straw for board making began in the northern United States and Canada, and a complete industrial production system has been formed to date. According to reports, the two countries have put into operation and construction of 13 factories, the production capacity of more than 600,000 m3, in addition to 8 companies are raising funds to build factories. In addition, Belgium, Sweden, Portugal, Russia and other countries have carried out such research, and have produced a variety of crop straw artificial wood panels. In the 1980s and 1990s, the factory system for making hard fiberboard and particleboard in bagasse was formed in the south of China. In recent years, the Chinese Academy of Forestry, Central South Forestry College, Northeast Forestry University, Nanjing Materials University and other units have also carried out research and development.
1. 1 straw made artificial board process
The process of crop straw board can be summarized into two kinds, namely integrated process and particle board process.
The integrated process flow is: crop straw → unpacking → removing impurities → heating extrusion → paste protection recycled paper (glass fiber layer can be added) → cutting edge sealing → finished board.
Stram it International (English) is the first company to have this technology. The raw materials are rice and wheat straw. The processing process does not require binders. The thickness of the finished board is 20-80mm. It is mainly used as wall material (such as the English countryside). Building a house) to replace clay bricks (According to statistics, China produces about 500 billion clay bricks per year, which is at the cost of destroying 10,000 hm2 of cultivated land). In the early 1980s, China's new building materials company introduced two straw board processing production lines from the company. Due to the community's doubts about the construction of straw boards, and the technical management of the production line is not timely, the operating conditions are not satisfactory.
The particle board process is: crop straw → unpacking → crushing → removing impurities → grinding → mixing with MDI (binder) → paving → pre-pressing and hot pressing → edge sanding → finished board.
Companies using this process include COMPAK, VALMET, HYMMEN, etc. The products can be used as substitutes for wooden boards in the furniture, flooring, packaging, construction, etc., sheet thickness is 4-35 mm, physical properties of the board. (fire, moisture, heat, mildew), mechanical properties (machined drilling, milling, sawing, etc.) and mechanical properties (MOE, MOR, IB) meet the industry standards of American ANSI-A208 and British BSEN312, and its development prospects broad.
1.2 Structure of straw-made artificial board
According to the structure and use of the product, the straw-based panel products that have been developed and to be developed can be roughly classified into the following three categories:
(1) Straw hard board: refers to straw particle board and straw medium density fiber board with density above 0.659g/cm3, which can replace traditional wood particle board and medium density fiber board for furniture manufacturing, packaging and interior decoration.
(2) Straw lightweight material: refers to low-density, lightweight, heat-insulating lining material made of straw, used as a wall material instead of clay brick. There are three kinds of lightweight walls, including extrusion method, flat pressing method and molding method.
(3) Straw composite material: refers to a sheet made of straw scrap as a filler and composited with inorganic mineral materials or plastics, used as building materials or packaging materials.
In addition, the relevant units have also made encouraging progress in exploring the use of straw to make cement formwork.
1.3 Technical difficulties in making straw-based panels
Since most of the surface of the straw has a substance which is not favorable for gluing, it is difficult to obtain satisfactory bonding strength (especially internal bonding strength) by using a conventional urea-formaldehyde resin or a phenolic resin glue. So far, almost all of the particle board factories that have been built at home and abroad have used isocyanate as an adhesive. This causes two problems: (1) cost problem because the isocyanate price is 8-10 times that of the urea-formaldehyde resin. Although the former is much lower than the latter, the absolute cost is still higher than the latter; (2) Sticky plate problems, such as the direct use of isocyanate adhesives, will cause severe sticking in the hot pressing process.
Crop straw is an annual plant with strong seasonality, loose texture, easy to worm, mildew and rot, and the problems of raw material collection, transportation and storage are outstanding. Although the straw land acquisition price is only a few tens of dollars, the final cost is likely to reach about 200 yuan, which is almost the same as the price of wood raw materials.
So far, straw-based wood-based panels have not been recognized by the majority of users in the market like wooden wood-based panels. Under the same quality conditions, the demand for straw boards is less than that of wood-based panels, and the price of products cannot be high. For wood-based panels, the profit margin will be affected, and you should pay full attention to this when conducting economic analysis.
The one-sided emphasis on the environmental characteristics of straw-based panels, and the blind optimism of its sales is not advisable. And the straw-based wood-based panel enterprises and wooden wood-based panel enterprises of the same scale can only guarantee the similar economic benefits of the two under the premise of very successful operation. A little carelessness will lead to an increase in the cost of straw-based panels and a loss in the factory.
In addition, the problem of the quality standard of straw artificial board, because the raw materials used in the board are different, the wood fiber and the straw fiber are different, the quasi-use objects are different, and the quality standards should be different. After the straw scrap processing, the straw has the problem of thickness and the strength of the sheet. Therefore, the equipment setting of the straw artificial board should also be improved. Different sets of equipment should be developed according to different yields.
2 Management status of straw-made artificial board
The data show that the world has made man-made boards using crop residues for decades. For example, China has introduced the German bagasse medium density fiberboard production line and the British straw board wall production line. However, the production of artificial boards by using the main straw straw and wheat straw as raw materials, especially the industrialized production line, has only a history of about 10 years. . The countries with outstanding achievements in the research of crop straw artificial boards in the world include China, the United States, Canada and other countries. Some straw scraping board factories have been built in North America, such as American Primchar Division and Canadian Isotxir Q Company. In recent years, due to various reasons, some straw-based wood-based panel factories in North America have suffered losses and have closed down again and again, and several companies are still insisting on production.
In China, so far, there are few production lines for straw production with industrial production. Hubei Jingzhou New Composite Materials Co., Ltd. uses the original particleboard production line to transform into a straw slab production line with an annual output of 8000m3. The products are sold to the Hong Kong market, but there is no market in China. Sichuan Guodong Group is about to build a production line that imports most of its equipment from abroad and has an annual output of 50,000 m3 of straw particle board. In addition, there are a number of domestic enterprises that intend to introduce foreign complete production lines, and some have already approved the project.
So far, the crop straw artificial board researched all over the world is straw scraper board, and some papers are written as “medium density fiberboardâ€. According to its process, it is still essentially a particle board. At present, the straw medium density fiberboard produced by high-temperature refining reported at home and abroad is basically a small sample in the laboratory. According to the domestic and foreign straw artificial board construction materials, the current straw artificial board production technology, the same scale straw artificial board enterprises and wooden wood-based board enterprises, only under the premise of very successful operation, can ensure the similar economic benefits. A little carelessness will lead to an increase in the cost of straw-based wood-based panels. The factory will lose money to manufacturers whose equipment is imported and invested in loans. The probability of loss will be higher. Therefore, the enterprises that are interested in investing in straw-based wood-based panel factories are very large. Investment risk.
Based on the above reasons, at present, there are many phenomena such as “laboratory research, less industrialization promotion, more feasibility reports, less actual investment and construction, more support for product public opinion, and less practical application†for straw-based panels. In general, the production of artificial straws at home and abroad is still in its infancy, the product variety needs to be developed, the product performance needs to be improved, the production cost needs to be reduced, the product application needs to be expanded, and the market sales need to be developed.
3 Research trend of straw-made artificial board
According to the crop stalk is an annual plant, seasonal, loose texture, easy to worm, mildew and rot, the production process should use the "waste recycling station" business model, follow the principle of long-term sharing of benefits, raw materials purchase in batches Dispersed storage, centralized transportation, which not only solves the problem of raw material collection, transportation and storage, but also ensures that the price of straw raw materials is much lower than that of wood raw materials. Therefore, this production and operation model needs to be researched and applied.
If the straw-based wood-based panel has all the characteristics and advantages of the dry fiberboard (wood), the appearance is the same as that of the dry fiberboard (wood), and the market is highly integrated, and does not require product promotion and market adaptation, and can be directly like dry fiberboard (wood). Used in furniture, flooring, speakers, television, packaging, construction and other industries. Therefore, the development of straw fiberboard production process is the most promising research in the technology of straw-based wood-based panel, which is also the urgently needed comprehensive utilization technology of straw industrialization.
In addition, the straw activation technology needs to be developed and improved. It is assumed that it can be effectively activated according to the structural characteristics of the straw cells and the characteristics of the chemical components, so that it has a certain self-gluing property, and then a small amount of low formaldehyde is released. The environmentally friendly urea-formaldehyde resin glue ensures product strength. This not only avoids the cost problems and sticking problems caused by the cyanate adhesive, but also ensures that the product cost is much lower than that of similar wood panels.
references
1 Wang Shengzhen, Han Helin, Yu Jianxiong, etc. Development prospects of using artificial crop boards for crop straws. Journal of Agricultural Machinery 12000:122- 123
2 Lan Dongli, Shi Kejun vigorously develops non-wood wood-based panels according to China's national conditions. Produced by the China Forestry Society Wood Industry Branch (19), 2000: 90-92
3 Xinghang wheat straw homogenizing board processing and application prospects Proceedings of the Wood Industry Branch of China Forestry Society (19), 2000: 93-98
4 Huajun, Lu Renshu wheat straw particle board preparation section processing technology research forestry industry, 2000, (2): 20-23
5 Li Yanjun, Gao Jianmin, Zhang Shuangbao, et al. Recent research and development prospects of straw-based panels in China. Building Panels, 2002, (1): 3- 5
6 Jiang Yuanzhou, Xiang Shilong compiled non-wood wood-based panels Beijing: China Forestry Publishing House, 1989
Development Status, Difficulties, Risks and Suggestions for the Development of Crop Straw Artificial Panels in Dingguo in 7 Weeks, 2002, (2): 3-6
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