At present, hot air nonwovens are mostly used as the surface material of toddler pants in China. The space structure of hot air nonwovens meets the conditions well, and the liquid bends through its pores, and the penetration time is relatively small. Its thickness is 3-5 times that of hot rolling, textile adhesive and melt blown with the same surface density. Good spatial structure increases the gap between fibers, and a certain thickness complicates the liquid recovery channel, which also acts as a barrier to prevent liquid backflow, thus reducing the backflow of liquid.
ES bicomponent fibers are the most commonly used fibers for air bonding. Its skin layer is low-melting polyethylene (PE), and its core layer is composed of polypropylene (PP) or polyester (PET), so that the non-woven fabric feels particularly soft and the tear strength is greatly improved. Among them, PP/PE and PET/PE fibers are collectively referred to as ES fibers. ES fiber has a high cost-effective advantage. ES fiber is a new type of raw material for sanitary products, so the price will be higher than that of ordinary PP fiber. But ES fibers have been widely accepted by the market in just over a decade. The following three reasons determine that ES fiber has higher cost performance:
(1) ES fiber raw materials are widely sourced and the price is stable, which is conducive to production;
(2) The application of ES fiber only increases the cost of toddler pants raw materials by 2% to 3%, but it can increase the price of toddler pants by 10% to 20%;
(3) Better water permeability, lower re-osmosis, and drier.
Silk is coagulated by the silk fluid secreted by the silk glands in the silkworm body. Mulberry silk consists of two parallel monofilaments with a triangular or oval cross-section.
The sericin covering the silk fibroin is a kind of adhesive, which makes the silk fibers stick to each other. According to the difficulty of solubility in hot water, it is divided into sericin I, sericin II, sericin III and sericin IV. , the four components of sericin form a layered structure. The viscosity and water absorption of sericin present difficulties in post-processing such as carding and stretching. Therefore, silk needs to be refined to remove sericin from silk fibers before making nonwovens. Sericin IIV has high crystallinity and high degree of orientation. During refining, some sericin IV remains, which is beneficial to the elasticity and feel of silk fabrics. After refining, there is a certain limit on the residual glue rate of silk, that is, it will be controlled within the range of 3% to ~5%. In addition, try to remove the grease that hinders the subsequent processing. Generally, the residual oil content is controlled below 0.5%.
Although silk fibroin and sericin are proteins composed of amino acids, their structures and properties are significantly different. There are many hydrophilic groups in the side chain of sericin molecule, which are easy to absorb water and dissolve in water; however, the molecular structure of silk fibroin is tight, water molecules cannot enter, the fiber is insoluble in water, stable to chemical substances, and has a large specific resistance, which is difficult to achieve. Suitable for high-speed carding processes. When using silk as a nonwoven, hydrophilic modification is required before carding.
At present, there are many research results that can improve the water absorption performance of silk fibers and improve the carding performance of fibers, such as soaking in aldehyde-based solutions such as formaldehyde and glutaraldehyde, modifying silk protein, and retaining sericin after refining. The silk fibers prepared by the processing method of sericin-containing silk fibers, the active sericin silk spunlace non-woven fabric processing method and other methods have certain water absorption and are not easy to generate excessive static electricity.
The upper layer of the pants adopts hot-rolled nonwovens, spunbonded nonwovens and all cotton nonwovens. Compared with ordinary walking pants, health care walking pants have a more prominent effect in preventing diaper rash and peculiar smell. Therefore, some enterprises and relevant scholars have developed silk toddler pants with health care function.
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