Fiberboard is a kind of board made from plant fiber through fiber separation, drying, molding or hot pressing. The production of MDF in China began in the 20th century, mainly in the production of wet fiberboard. Due to the serious environmental pollution caused by the wastewater from the production of wet fiberboard, it was greatly limited for a period of time; In the late 1980s, the production technology became increasingly perfect, and with the expansion of the use of fiberboard, it soon entered a high-speed development stage. After 2000, the state issued relevant preferential policies to encourage the development of fiberboard industry, which provided an excellent opportunity for China to vigorously develop fiberboard production, mainly reflected in the continuous increase of production capacity and greatly improved production efficiency of fiberboard manufacturers.

Two key sections in fiberboard production are raw material preparation and sizing.

Fiber preparation determines the basis of fiberboard. There are many contents and complicated processes. Let's briefly understand. The process requires that the wood be first made into wood chips, then sorted, washed with water, digested, and then sent to the thermal mill, which is the most unique and key equipment in the production of fiberboard, and of course, the relative price is the most expensive. The fibers are grinded out with a thermal mill. High temperature, high-speed rotation and harsh noise are the harsh conditions and dangerous environments that cannot be avoided, otherwise the fibers will not come out easily. The thermal mill is the most complex and critical equipment in the fiberboard production line. The three internationally renowned manufacturers of thermal mills that have a great impact on China's wood-based panel industry are METSO, ANDRITZ, Austria, and PALLMANN, Germany. At present, these three companies can provide various specifications of thermal mills to the international market to meet the needs of 30000~400000 m3/a medium/high density fiberboard production lines and paper production lines of the same specifications. It is clear that the high-end products are all from abroad. Now there are also towns in China, Jiangsu Fuma, and the level is very high.

The glue for fiberboard is pipe glue. The adhesive is sent to the glue tube group between the hot mill and the dryer by the glue pump. With the help of high pressure steam in the hot mill, the fibers are rapidly ejected in a dispersed suspension state. The sizing nozzle sprays the foggy glue at a pressure 0.1~0.2 MPa higher than the steam pressure in the pipe, so that the adhesive and fibers can be fully and evenly mixed. The mixed materials enter the drying pipeline from the blow off pipe. The diameter of the drying pipeline is 1.0~2.6 m (the diameter of the pipeline varies according to the output). The length of the pipeline is about 120 m. The end of the pipeline is connected with the cyclone separator to separate the dry fiber from the dry gas. The whole drying time is 5~10 s. Because of the extremely short time, it is also called the "flash" pipeline dryer. The system is applicable to thermal medium indirectly heated by steam, hot oil, etc. and directly heated by hot flue gas. In our factory, hot flue gas is actually used for direct heating, which can be described as simple, rough and highly efficient.

The traditional adhesive is urea formaldehyde adhesive, and the amount of sizing is very large. The amount of sizing per cubic meter of fiberboard is up to 120kg. After our exploration and attempt, we began to use MDI for fiberboard. MDI was used for fiberboard. The pipe sizing was wet and hot. It scared MDI to think about it, but it was impossible to get anything without going into the tiger's den. This sizing method could even use MDI. For this reason, we also specially designed a sizing system in that year to constantly check and eliminate one security risk after another, such as MDI dispersion, MDI pre reaction, MDI sticking to the pipe wall and cleaning problems.

The problems of subsequent pavement, demoulding and hot pressing curve have been solved successively, and formaldehyde free density fiberboard has finally come out. Formaldehyde free fiberboard has good environmental protection performance, but it also has some problems such as hardness, poor sawing, and immovable facing, which can be alleviated by some means. If we don't let go of the details, it will be difficult to do anything. To solve the problem, we need to look at the main contradiction, which is the power source for progress.

The output of fiberboard is very large, which used to be 3 times the annual output of chipboard. Now people gradually rationally realize the rationality of the production and application of chipboard, and the new production capacity is very fast, with one increasing and the other decreasing. However, the use of fiberboard is still very extensive and irreplaceable. In decoration or furniture, where complex shapes are required, fiberboard is almost impossible. In special places, such as the door panel, back panel of panel furniture and the bottom plate of drawer, fiberboard is also mostly used.

When we choose fiberboard, we must choose fiberboard produced by regular large factories. If there are special requirements for environmental protection, we should choose fiberboard produced by MDI glue to ensure no formaldehyde emission. Others also have some new adhesive board making technologies, but they are not perfect and have not formed a real batch production. In addition, choose fiberboards such as beautiful ones with bright colors. The fibers prepared are good, the bark is added less, the raw materials are single and stable, and there is no messy adhesive added.