What are the specific steps of the nonwoven dry-laid technology? (Professional skills and pure dry goods)

Dry-laid webs are relative to wet-laid webs. The non-woven fabrics obtained by dry-laid webs are called dry-laid non-wovens, which currently account for more than 50% of the world's total non-woven production. Dry-laid web technology includes three processes: preparation before web forming, fiber carding and web forming. 1. The tasks of the preparation process before web formation (1) Feed and open fiber materials with different properties and different varieties separately or together to feed and open, so that the compressed fiber blocks in the fiber pack are mechanically hit and torn. And loosen into small pieces of fiber bundles. (2) Store the opened fibers in a fiber bin and mix them in multiple bins so that fibers with different properties can be fully mixed. (3) Make a uniformly mixed fiber layer for carding by a carding machine. Non-woven fabric is a product made of fiber raw materials after opening, removing impurities, blending, and carding by a carding machine. The quality of the fiber web before reinforcement directly affects the quality of the final product. Therefore, whether the preparation process before web formation is reasonable and whether the equipment configuration is appropriate will affect the fiber opening and mixing effect and the uniformity of the fiber web. 2. Fiber carding After the preparation process, most of the fibers are in bundles. In order to make them into single fibers, they must be carded. The equipment used can be a roller carding machine or a flat carding machine. In order to meet the requirements of high output, high quality and high degree of automation of nonwovens at home and abroad, many models of special carding machines for nonwovens have been developed since the 1980s. But the action mechanism of the card clothing on the fibers of various carding machines is the same. 3. Netting The process of single fiber (short or long fiber) forming a fiber net in a certain way is called netting. In the non-woven fabric industry, the fiber web is the product after reinforcement, so the quality of the fiber web has a direct impact on the quality of the final product, such as strength, uniformity, and quantitative. In particular, the state or arrangement of fibers in the fiber web is more important. In dry-laid nonwovens processing, web formation refers to short fiber web formation. The fiber web directly peeled from the doffer with a chopper or a cotton stripping roller has the following problems: one is the poor uniformity of the web; the other is the large difference between the longitudinal strength and the transverse strength of the web (up to 10:1 ~12:1); Third, the basis weight and width of the fiber web cannot meet the requirements of the product, and often cannot be directly reinforced. It must be improved by layup or special web forming.