The Development History of Chinese Paper Machine Felt

In 1941, China produced its earliest paper making felt – wool woven felt, ending the history of China’s complete need to import paper making felt.
The early paper making felt in China were made of 100% wool, and by the late 1950s, synthetic fibers such as nylon began to be used for paper making felt. Nylon fiber has high strength and good wear resistance. If 15% to 20% nylon fiber is used, the service life of paper making felt can be extended by about 30% to 50%. In the early 1960s, another achievement in the field of technology for paper making felt was the “transgender treatment”. Because wool contains protein, bacteria in pulp can damage wool fibers. After denaturation treatment, a certain molecular structure in wool can be altered to improve its resistance to biology, chemistry, and heat. The processed felt can extend its lifespan by about 15% to 50%.
In the early 1970s, the successful development of needle punched flocking felt broke the previous monopoly of wool woven felts and also marked the birth of the second generation of paper making felt in China. Shortly thereafter, China’s first needle flocking machine was successfully developed in Shanghai, creating a new textile production technology of “weaving without shuttle and finishing without water”. Afterwards, engineers in China’s textile industry devoted themselves to research and took a unique approach. They faced the reality that there were no soluble chemical fibers in China at that time, abandoned ready-made weaving methods, and surpassed the framework ideas of foreign technical authorities. They relied on themselves and independently developed and finally successfully developed China’s unique non-woven needle punched flocking paper making felt, and the raw materials used for the wool layer were mainly nylon and polyester. At that time, this technology was still blank internationally.
At this point, China began mass production of ordinary needle punched (BOB) paper making felt. BOB felt is composed of a base fabric layer and a fiber layer. The base fabric generally accounts for 20% to 50% of the weight of the finished product. It is divided into various types such as warp, thin weft, fine weft, and no weft. The warp is a blend of yarn and nylon filament to increase tension, reduce yarn count volume, and facilitate specification stability and water filtration. The warp and weft density of the base fabric is small, especially for felt made of thin, fine, and no weft, which can reduce drainage resistance and improve the water filtration performance of the felt. The raw materials for the fiber layer are generally nylon and polyester short fibers, which have a very wear-resistant surface and can improve or eliminate paper felt marks, enhancing the smoothness of the paper. The base fabric layer and fiber layer are repeatedly needled by a needle punching machine to firmly bond together, achieving the purpose of protecting the base fabric and increasing the water filtration performance of the felt.
Compared with woven felts, BOB felts have the characteristics of good water filtration and breathability, simple production process, convenient production, and long service life. They are widely used in China’s paper industry. Its service life can be extended by 50% to 100% compared to woven felts, thereby reducing the consumption and production cost of felts per ton of paper, as well as reducing downtime for changing felts and improving the operating efficiency of paper machines. The emergence of BOB felts has made the performance of China’s second-generation paper making felt more perfect. This product has far better water filtration performance, surface smoothness, anti hair removal performance, service life and other properties than the original products, and the production cost is also quite low.
Since the 1980s, with the rapid development of the paper industry, some wide width, high-speed, and high line pressure paper machines have been successively applied in China’s paper mills. The requirements for the matching paper making felt of these paper machines have also increased accordingly. BOB felts can no longer meet the requirements of new paper machines. In order to produce normally, some paper mills have imported BOM press felts from abroad. From then on, China’s paper industry began to have an understanding of BOM felts. Some developed paper-making countries in the West have been developing and promoting BOM felts since the late 1960s, while China started this work in the late 1980s and early 1990s. This means that China’s third-generation paper making felt appeared nearly 20 years later than developed countries. At present, BOM paper making felt have gradually become the dominant product in the market, with a penetration rate of about 80%.
BOM felts consists of a bottom mesh layer and a fiber layer. The bottom mesh layer is made of single and single/double stranded synthetic fiber materials, and is woven using different weaving techniques to create endless fabrics with single-layer, double-layer, multi-layer, and layered (1+1, 1+2, 2+2 ┄) structures; The commonly used synthetic fibers in the fiber layer include nylon staple fibers, polyester staple fibers, and other fiber materials; BOM felts are made by layering short fibers of the same or different thickness on the bottom mesh, and then processing the bottom mesh layer and fiber layer through needle punching, heat setting, and other special finishing treatments.
BOM felts have excellent properties such as flat surface and stable specifications. Due to their stiff texture, they generally do not fold and have a low elongation and contraction rate; The strength should be more than twice that of BOB felt, and it should be wear-resistant and corrosion-resistant; High porosity and good water filtration performance. Due to its ability to withstand high linear pressure, the dryness of the pressed paper sheets is generally 1% to 3% higher than that of BOB felts, which is beneficial for increasing vehicle speed and saving energy; BOM felts are washed with high-pressure water to maintain their cleanliness; The advantages of longer service life are 1-2 times longer than BOB felts.