Tangshan Sanyou Group Chemical Fiber Company has developed recycled fiber containing 50% recycled pulp after 5 years of research and has achieved large-scale mass production. The company's newly upgraded differentiated recycled fiber production line has an annual capacity of 40,000 tons, ranking first in the domestic industry; to date, cumulative production of recycled fiber has exceeded 10,000 tons. Converted based on China's 2023 national cotton yield per unit area, this output is equivalent to planting 74,460 mu of cotton. In January 2024, the China National Textile and Apparel Council appraised its industrialization technology for preparing viscose staple fiber from waste cotton as reaching internationally leading levels.

Key Points

  • Tangshan Sanyou Group Chemical Fiber Company developed recycled fiber containing 50% recycled pulp, with the project initiated in 2019 and successfully achieved after 5 years of research.
  • The upgraded differentiated recycled fiber production line has an annual capacity of 40,000 tons, ranking first in the domestic industry, with cumulative output exceeding 10,000 tons, equivalent to the cotton yield of 74,460 mu.
  • In January 2024, the China National Textile and Apparel Council appraised its industrialization technology for preparing viscose staple fiber from waste cotton as reaching internationally leading levels.

From Industry Pain Point to Technology Project

"Every year, over 20 million tons of waste cotton textiles are discarded in China. But in fact, these seemingly useless old cotton clothes can produce 0.99 tons of color-separated cotton yarn per ton." These figures prompted Liu Hui, Director of the Product R&D Department at Tangshan Sanyou Group Chemical Fiber Company, to resolve to "turn waste into treasure." In 2019, he led his team to invest in recycled fiber technology research, aiming to turn old cotton clothing into fiber and spin it into cotton yarn.

To renew old clothing, it must first be made into pulp, then into fiber, spun into cotton yarn, and further woven into cotton fabric. Among these steps, the uniform polymerization of recycled pulp components is fundamental and key to determining whether fiber can be produced. Pulp from different origins has varying polymerization properties, and dissimilar cotton fibers that are difficult to dissolve in solution can clog spinneret holes. After repeated experiments, the team identified the patterns of pulp polymerization degree changes and attempted to convert dissimilar cotton fibers by adjusting solution ratios.

Process Innovation and Mass Production Breakthrough

After entering the thousand-ton pilot scale-up stage, the spinneret clogging problem was still not completely eliminated. Liu Hui pointed the breakthrough to the glue preparation process: alkali liquor impurities settle slowly, and after ultrafiltration microporous filtration, impurities still clog the spinneret. Team members proposed adding a glue homogenization treatment device. After its introduction, the prepared spinning glue became clearer, and the homogenizer's repeatedly rotating rotor transformed stubborn foreign matter in the spinning glue, becoming an effective "killer move" for efficiently converting pulp foreign matter.

In February 2023, when the recycled pulp ratio was increased to 50%, all production indicators on the monitoring screen stabilized, marking a major breakthrough in the trial, and the key technology for turning old clothing into recycled fiber was thus conquered.

Capacity and Market Destinations

Liu Hui introduced that the newly upgraded differentiated recycled fiber production line has an annual capacity of 40,000 tons, ranking first in the domestic industry in output, equivalent to planting 74,460 mu of cotton based on China's 2023 national cotton yield per unit area. He is preparing to shift capacity from the 8,000-ton/year pilot production line to a 40,000-ton/year large-scale production line.

On the market side, Li Xiaodong, Director of the company's Sales Department, said that due to the low-carbon attributes of recycled fiber, European apparel brands particularly value this; the products are sold to more than 10 spinning enterprises domestically and internationally, and are ultimately adopted by more than 30 well-known apparel brands.

Wang Chunsheng, Chairman of Tangshan Sanyou Group, stated that next they will continue to explore the application ratio of recycled pulp and further expand recycled fiber capacity.

Source: Old Cotton Clothing's Journey to "Fiber" -- Economy·Technology -- People's Daily Online · Originally published on 2024-11-13