关键词: 木棉纤维, 棉纤维, 水刺非织造布, 油液吸附, 吸油纸

Abstract: The secretion of facial oil in the human body is increasing, while the existing facial tissues on the market are mostly made of flax pulp and polypropylene materials, and have the shortcomings of non-skin-friendliness, poor oil absorption effect and refractory degradation. This paper aimed to make full use of the large and medium cavity and natural skin-friendly characteristics of kapok, and to prepare green oil-absorbing facial tissues with excellent oil-absorbing performance via hydroentanglement by blending with cotton fibers.
Firstly, the kapok and cotton fibers were prepared by the carding machine to prepare the fiber web in different proportions (010, 37, 55, 73, 100). Then, the hydroentangled nonwovens were prepared by the front and back and three-way hydroentangled process with increasing pressure sequentially. The surface morphology and pore size distribution of the nonwovens were characterized by scanning electron microscopy and porous material analysis instrument. and the surface wettability of the nonwovens was analyzed by optical contact angle measuring instrument. Finally, the oil absorption and instantaneous adsorption properties of the nonwovens were also tested and characterized. A polarizing microscope was used to observe the morphological characteristics of the fiber after absorbing oil, and a comparative analysis was conducted with the oil-absorbing performance of existing oil-absorbing facial tissues on the market.
As can be seen from the scanning electron microscope, cotton fibers and kapok fibers are evenly distributed in the nonwoven, and mechanical hydroentanglement will not destroy the large and medium cavity structure of kapok, which provides a good structural basis for its oil absorption. When the ratio of kapok to cotton is 7:3, the pore size of the nonwovens ranges from 0–60.87 μm, and its average pore size is the smallest (25.92 μm). Furthermore, the pore size distribution curve has obvious peaks, and the overall pore size distribution is relatively uniform. The contact angle between the five nonwovens and deionized water is greater than 130°, and the contact angle with GTCC oil is less than 70°, indicating good hydrophobic lipophilicity. This can ensure that only grease is adsorbed and not contaminated with water during use. The comparison sample 6# shows the characteristics of oil and water amphipathicity. In addition, the addition of kapok can significantly improve the oil absorption rate and oil retention rate of the nonwovens. When the ratio of kapok to cotton is 7:3, the nonwoven has the highest oil absorption rate (31.38 g/g) and the highest oil retention rate (94.69%). The oil droplets will not only adhere to the surface of the fiber, but also produce a wicking effect in the space between the fibers, and a small part of the oil droplets will penetrate into the cavity of the fiber, showing a dual-scale oil adsorption behavior between the cavity and the pores between the fibers. The adsorption rate of added kapok (3#, 4#, 5#) is greater than that of unadded kapok (1#). When the content of kapok is greater than 30%, the average adsorption rate within 0.5 s is greater than 1.000 g/s, and when the mixing ratio of kapok to cotton is 55, the average adsorption rate within 0.5 s is the largest (1.569 g/s). The average adsorption rates of comparative samples 6# and 7# within 0.5s are only 0.263 g/s and 0.268 g/s.
Kapok fibers and cotton fibers are blended to prepare hydroentangled nonwovens, and cotton fibers are evenly distributed in the nonwovens as a supporting structure. With the increase of kapok content, the average pore size shows a downward trend and the pore size distribution tends to be increasingly uniform, which greatly improves the oil absorption capacity of nonwovens under the premise of ensuring skin-friendliness and green degradability. At the same time, the nonwovens also have good oil and water selectivity and instant adsorption performance, which can ensure that they only absorb human facial oil and do not absorb facial moisture during use, avoiding skin dryness. This work provides a reliable method for the subsequent development of new oil-absorbing facial tissues, and provides certain reference significance in expanding the application field of kapok.

Key words: kapok fiber, cotton fiber, hydroentangled nonwovens, oil adsorption, oil absorbing paper