Foreword

Since the reform and opening up, China's wood-based panel industry has continued to develop, and the production technology, output and consumption structure of the products have undergone remarkable changes. In the forestry industry, an emerging industrial sector has been formed from production to circulation and service. The sustained and steady growth of the national economy and the development of the forestry industry have contributed. According to statistics, China's wood-based panel industry grew at an average rate of 15% per year in the 1980s, and grew at an average rate of 25% per year in the 1990s, far higher than the GDP growth rate in the same period in China. By the year of 2001, more than 6,000 man-made board factories have been put into operation in the country, and about 500 large-scale plants have a designed production capacity of about 30 million m3/a. The total output in 2001 is 21,108,200 m3/a, compared with the previous year. The increase is about 5.45%. The industrial structure of wood-based panels based on plywood, particleboard and MDF has been formed and continues to grow. China is a large country in the production and consumption of wood-based panels, and its output ranks second in the world. According to experts' prediction, the demand for wood-based panels in China in 2005 was 28.05 million m3, and in 2010 it was 32.85 million m3. In the current state of the domestic commodity market is generally surplus, the wood-based panel industry is one of the few industries in China where consumption growth is greater than production growth. Therefore, relevant experts combine the market demand and the forecast analysis of import and export trade: China's wood-based panel industry still has a bright future for sustainable development. Wood-based panels are products in which wood or non-wood materials (such as bagasse, vines, etc.) are broken and joined together. The wood-based panels on the market today are mainly divided into two types: wood-based panels and bamboo-based panels, and some wood-based panels made of non-wood materials such as straws.

Wood-based panel

Wood-based wood-based panels are made of wood or wood waste as the main raw material, processed by physical and chemical processing and mechanical cutting, processed into structural units of various shapes, and then slabs which are assembled or laminated into different structural forms. Material. Wood-based wood panels alleviate the lack of pressure on wood resources. It is a good way to improve the utilization rate of wood by using fast-growing materials and small-diameter materials, and basically overcomes some of the defects of wood, and realizes the use of small materials and inferior materials. .

Wood-based panels mainly include wood plywood, wood fiberboard and wood particle board.

The production process is:

Plywood: logs→cutting→peeling→cooking→rotating→drying→gluing→composite→preloading→hot pressing→cutting→sanding→inspection→input

Fiberboard: Residue→Shavings→Preheating Cooking→Hot Grinding→Air Fiber Separation→Drying→Sizing→Pavement→Preloading→Hot Pressing→Truncation→Sanding→Inspection→Warehousing

Particleboard: Residue→Shavings→Shavings→Drying→Screening→Sizing→Pavement→Preloading→Hot pressing→Truncation→Sanding→Inspection→Warehousing

Wood-based panels are the main artificial boards on the market today, and are the main materials for making furniture and interior decoration.

Bamboo wood panel

Bamboo wood-based panel is a kind of artificial board made of bamboo or bamboo scrap as the main raw material, processed by physical and chemical processing and mechanical cutting, processed into various structural units of different geometric shapes, and slabs of different structural forms are glued after sizing. . It basically eliminates the anisotropy of bamboo, uneven material and easy to dry; it can be free of insects, mildew and no deformation.

Bamboo has high strength, good rigidity and wear resistance. It is an excellent engineering structural material. However, China's research and development on the deep development of bamboo, bamboo wood-based panels, is relatively lagging behind. The development of bamboo wood-based panels in China began in the 1970s and developed in the 1980s. In the early 1980s, bamboo was used as a substitute wood material for sustainable cultivation. It attracted people's attention and invested a lot of manpower and material resources to research and develop. Bamboo wood-based panels have made great progress. Today, bamboo wood-based panels have extensively replaced wood and wood plywood in construction, packaging, vehicles, interior decoration, and furniture. Since the bamboo itself is a material with small diameter, hollow and thin walls, this greatly limits the use of bamboo, and the development of bamboo wood-based panels has made bamboo a large-format, high-strength plane or type. The surface materials have enabled China's bamboo resources to enter the era of industrial utilization.

Bamboo wood-based panels mainly include: bamboo mat plywood, bamboo curtain plywood, bamboo plywood, bamboo laminated board, bamboo scraping board and bamboo composite board.

The main production process of bamboo wood-based panels is:

Preparation of constituent units → drying of constituent units → sizing of constituent units → formation and hot pressing → processing of bamboo wood-based panels.

The earliest developed bamboo wood-based panels in China are Sichuan bamboo-made plywood, which is mainly used as a box board and a small amount as a building formwork. In the late 1980s, Hunan developed bamboo mat plywood as a building formwork, Zhejiang developed a bamboo laminate as the car floor, and Nanjing Forestry University developed bamboo plywood for the car floor and building formwork. These sheets are high-strength and dimensionally stable and are now widely used in construction and vehicles, reflecting good results. After entering the 1990s, high-strength laminated bamboo slabs and bamboo flooring have been developed in various places, which have formed a large production scale and are widely used in building stencils and interior decoration. Although the bamboo particle board has been developed and produced, it has not formed a scale. Bamboo composite panels are mostly in the research and testing stage. There are now more than 200 manufacturers of bamboo wood-based panels in the country, mainly in Zhejiang, Hunan, Sichuan, Jiangxi, Anhui, Fulu and other provinces.

Comparison between wood-based panels and bamboo panels

Due to the different materials of bamboo and wood itself, bamboo wood-based panels have many excellent properties in terms of physical and mechanical properties, such as high strength, good elasticity and impact resistance. Non-wood wood-based board raw materials.

Due to the differences in the structure, shape, material properties and wood of bamboo, some processes and equipment still differ, taking the production of bamboo mat plywood as an example:

    The production process of bamboo mat plywood is:

Bamboo mat preparation → drying → coating → blanking → aging → hot pressing → sawing → inspection → ordinary bamboo plywood.

It can be seen that the process after the sawing is the same as that of the general plate, and the production process of each process before the hot pressing is different. :

First, bamboo mat preparation (wood wood panel without this process)

The bamboo weaving of bamboo plywood has two kinds of latitude and longitude seats and curtain hanging.

The latitude and longitude seats are bamboo mats woven from 1-1.5 mm thick bamboo. The curtain hangs are made of bamboo inner springs and are suspended as curtains in the form of curtains.

Second, bamboo mat drying

The drying method can be dried naturally or in a mesh belt dryer.

The suitable moisture content of bamboo mat is 8-20%. If it is too low, the plate will be brittle, the fluidity of the resin will also be deteriorated, affecting the quality of the glue. If the temperature is too high, the hot pressing time will increase. It must be exhausted several times. The process is difficult to master. The color of the surface becomes black, which affects the physical and mechanical properties and appearance quality of the product.

Third, glue

There are two kinds of gluing methods: manual gluing and gluing machine. The rubber used is phenolic and urea-formaldehyde. Practice has proved that the use of phenolic glue is better than urea-formaldehyde, but the cost is higher.

Fourth, Chen Hua

In order to make the glue fully infiltrate the bamboo mat and improve the quality of the glue, after the glue is applied, the bamboo mat should be placed for a period of time and then placed or assembled for a period of time and then hot pressed.

Five, the blank

When producing bamboo plywood, the blank can be odd or even layer structure (wood plywood can only be an odd structure), and the warp and weft mixed bamboo plywood needs to be staggered.

Sixth, hot pressing

The appropriate temperature, pressure, and time for hot pressing vary depending on the type of rubber and the number of layers. The temperature of the urea-formaldehyde glue is 120-125 ° C, the temperature of the phenolic glue is 130-140 ° C, the pressure of both is 2.5-4 MPa, the time is lengthened with the increase of the number of layers, and the time of the phenolic glue is longer.

At present, bamboo mat bamboo plywood is one of the fastest growing and largest varieties of bamboo wood-based panels in China. It is mainly used as a building formwork, and a small amount of bamboo fiber board made of veinaldehyde rubber is used as a package board. The traditional wooden formwork has poor surface quality, time-consuming assembly time and long construction period. The steel molds promoted in the 1970s are small in size, large in seams, heavy in weight, difficult to demould, rough in surface, and easy to rust and deform; The wood plywood formwork used in the ages requires a large amount of wood resources, and the number of turnovers is small, and the cost is high, so it is not suitable for large-scale use. Bamboo mat bamboo plywood has high strength and good toughness; wide width and less joints; smooth surface, easy demoulding; water resistance, heat resistance, no deformation; high turnover times, has been widely used in construction, replacing Wood molds, steel molds, and wood plywood are used as concrete templates for high-rise buildings, bridge dyes, dams, and tunnels. The development of bamboo wood-based panels is fast, the product cost is low, and the application is wide. However, due to the late development, it is in its infancy. Like the wood-based panels, there are problems such as poor quality and insufficient performance. In the future, it is necessary to develop bamboo materials suitable for production. The high-precision equipment of plywood and the improvement of the manufacturing process to expand the product market enable the smooth development of bamboo wood-based panels.