Application Of Biodegradable Fibers in Nonwoven Fabrics

Since the late 1960s, nonwoven fabrics have been widely used in the field of civilian textiles and industrial textiles due to their characteristics of wide raw materials, short production process and low cost, and have maintained a high growth trend in the world.

With the rapid development of polymer materials, while its advantages are affirmed, its shortcomings are also found, that is, most of the artificially synthesized polymer materials are difficult to degrade in nature, and the non-degradable polymer materials cause "white pollution" to the environment. Some chemical fibers in textile materials are difficult to degrade and have become a new source of pollution. At present, the main methods used to solve this problem are recycling, incineration, and degradation. Among them, degradation is considered the best method. Degradation includes biological degradation, photodegradation, and thermal degradation. Biological degradation is particularly noteworthy due to its low cost and effectiveness. Textiles made of biodegradable fibers can decompose into carbon dioxide and water under the action of microorganisms, which is harmless to the environment. Biodegradable fibers are also widely used in medicine, horticulture, and construction due to their excellent performance and outstanding biocompatibility. Biodegradable nonwoven fabrics are nonwoven materials made of biodegradable fiber, which can slowly decompose in the natural environment under the action of microorganisms.

At present, there are mainly two types of biodegradable textile fiber materials used in nonwoven, one is the green environmental protection fiber directly derived from natural high molecular substances, such as: Lyocell fiber, Modal fiber, corn fiber, soy protein fiber, seaweed fiber, chitin fiber, etc., all belong to green environmental protection fiber; the other is high molecular chemical synthetic materials, such as: polylactic acid fiber (PLA), polyglycolic acid fiber (PGA) and their polymer fibers (PLGA), these fibers not only have good biocompatibility, but also can be biodegraded into carbon dioxide and water, have no toxic side effects to the human body, and are also a new type of high molecular material that has attracted much attention.

Lyocell fiber

Lyocell fiber is an environmentally friendly cellulose fiber, the production process is pollution-free, has good biodegradability and moisture absorption, softness, wearing comfort. It is different from the ordinary viscose fiber, which is to dissolve the fiber pulp (wood pulp or cotton pulp) directly in an organic solvent, the solution after filtration, degassing and other processes is squeezed, spun, and solidified into fibers. The performance of this fiber is very superior.

● It has all the natural properties of cellulose fibers, including good moisture absorption, comfortable wearing, good luster, excellent dyeability and biodegradability, and can be completely biodegraded in a short period of time.

● High dry, wet strength and wet modulus.

● The shrinkage rate of the fabric is very low, its fabric size stability is good, and it is washable.

● The cross-section of the fiber is round, the surface is smooth, and the fabric has the luster of silk.

Lyocell fiber is widely used in the production of spunlace nonwoven fabrics. Because the fiber has high strength, good water absorption, and can be fibrillated during processing, it has excellent properties for nonwoven fabrics. The fiber is stronger than other cellulose fibers, has less elongation, high initial modulus, small product deformation during the spunlace process, after spunlace, and after finishing, and the product has good dimensional stability. Lyocell spunlace nonwoven fabric can be widely used in disposable wiping items, medical gauze, women's sanitary napkins, protective clothing, filter materials, coating base cloth, battery separators, ecological composite materials and other fields.

Chitin fiber

The raw material for producing chitin fiber comes from the shells of crustaceans, shrimp, clams, and other shellfish aquatic animals. It is the most abundant natural organic matter on Earth after cellulose. Because chitin has the biological functions of collagen in higher animal tissues and cellulose in higher plant tissues, it has good biocompatibility with both plants and animals, and also has biodegradability. Its main characteristics are:

● Chitosan is a natural polymer with no toxic side effects. Its chemical structure is similar to that of heparin, and its chemical and biological properties are similar to those of human tissues. Its products do not cause rejection in the human body.

● The multi-functional chemical structure of chitosan itself makes it exhibit excellent biological activity. It has been proven to have antibacterial, reducing serum and cholesterol content, stimulating the growth of body cells, promoting humoral immunity, cell immunity and other functions.

● Chitosan will be broken down into low-molecular substances under the action of enzymes, which can be completely absorbed by general organic tissues.

● It is non-toxic, odorless, heat-resistant, alkali-resistant, and corrosion-resistant. It has antibacterial, anti-mildew, moisture-absorbing, wound-healing, and blood-clotting functions.

Due to the fact that chitin fiber is non-toxic and non-irritating to the human body, it has natural physiological activity, and at the same time, because it contains amino acids in its molecular structure, it has strong adsorption and integration, so it has a wide range of applications.

1. Artificial skin. Chitosan water-jet nonwoven fabric has the functions of isolating external air, inhibiting bacteria, avoiding cross-infection, controlling fluid loss, and stimulating skin cells. Chitosan itself has a chemical structure similar to heparin, excellent biocompatibility and biological activity, and does not cause abnormal immune, rejection, and allergic reactions in the human body, making it an ideal material for making artificial skin.

2. Medical dressings, bandages, and other covering materials for wound protection. The use of chitosan water-jet nonwoven fabric as a medical dressing, bandages, and other covering material for wound protection has many advantages. First, it can adsorb serum proteins squeezed out from the wound, stimulate the growth of body cells, and has the functions of hemostasis, analgesia, and promoting wound healing. Second, it produces hydrophilic gel substances at the wound site, preventing bacteria from passing through, and has the effects of inhibiting bacteria, anti-inflammation, and preventing infection. In addition, it also has high strength and good moisture-wicking properties, which can absorb blood and exudate, keep the wound dry, and provide a good environment for wound healing.

3. Beauty masks. The beauty masks developed with chitosan water-jet nonwoven fabric have functions of moisturizing, oxygen supply, and activating cells, which can moisturize, nourish, and protect the skin.

4. Food covers and packaging materials. Food covers made of chitosan nonwoven fabric have good sterilization, preservation, and safety functions. Medical material packaging bags made of chitosan nonwovens have functions such as breathability and preventing mold growth.

Chitosan spunlace nonwoven fabric can also be widely used in the production of wet face towels, baby wipes, cosmetic cloth, filtration and purification of tap water and beverages, used as surgical covers, surgical masks, disposable household medical products, trauma protection materials (such as bandages, gauze, band-aids) and so on. Due to its excellent biodegradability, it can be decomposed into low-molecular substances by enzymes in a short period of time, without any pollution to the environment, making it an ideal "green product".

Viscose fiber

The viscose fiber has a series of characteristics that cannot be fully possessed by synthetic fibers, such as good skin contact, wearing comfort, physiological safety, moisture absorption, easy to manage, and its products are easily biodegradable. Therefore, nonwoven fabrics made of cellulose fibers have unique uses in the medical, nursing, hygiene, cosmetic, and other industrial fields. The viscose spunlace nonwoven fabric has excellent drape and extremely soft feel, fluffy and breathable, high strength, good moisture absorption, not easy to pilling, and does not contain chemical adhesives. It is widely used in hygiene materials, household living products, and decorative fabrics.

The viscose fiber can be used alone as a web for the production of spunlace nonwoven fabrics, or it can be mixed with other synthetic fibers to compensate for the shortcomings of synthetic fibers (such as poor moisture absorption). In the production of spunlace nonwoven fabrics, it is often mixed with 50% viscose fiber and 50% polyester fiber. The viscose / polyester spunlace nonwoven fabric is treated with repellency to make surgical coverings, which have good softness, drape, moisture absorption / waterproofness, and repellency. Using spunlace nonwoven fabric to make surgical gowns and medical bed sheets is an ideal material, especially because its surface is chemically treated to be repellent. When a patient's blood splashes on the surgical gown during surgery, the water droplets roll down, protecting the medical staff's clothes from contamination and the body from viral infection.

Polylactic acid (PLA) fiber

Polylactic acid fiber is made from renewable corn, wheat, and other starch as raw materials, fermented into lactic acid, and then polymerized and spun. Its waste in soil or water, under the action of microorganisms, is decomposed into carbon dioxide and water, and then becomes the raw material of starch under photosynthesis, which is conducive to ecological balance. It is a fully biodegradable fiber, known as green fiber. This fiber is based on lactic acid. Lactic acid is a common natural compound in plants, animals, and microorganisms. The fabric made of polylactic acid fiber has a comfortable skin contact and touch, and also has the luster of silk.

Polylactic acid is a thermoplastic polymer, and the biodegradable fiber imitating polylactic acid has good heat resistance and thermal stability. After 500 hours of sun exposure, it can still maintain 90% of the strength. The product feels soft, the gloss is soft and bright, and the dyeing performance is good. Due to the existence of a large number of non-crystalline structures in the internal structure of the fiber, it decomposes quickly in the presence of water, bacteria, and oxygen. The nonwoven fabric produced by it is currently widely used.

1. In agriculture and gardening, it can be used as a tree root packaging bag, a sheet material for seedling beds, a film material for nurseries, a sheet material for vegetation, a multifunctional roll material, a weed-preventing film, an inner lining sheet, a slope protection greening roll material, a dust-preventing sheet, a drainage roll material, a water-absorbing roll material, a sludge dewatering bag, and a filtering membrane.

2. In the field of health care, it can be used as surgical gowns, surgical coverings, masks, diapers, women's sanitary napkins, and other physiological hygiene products.

3. In terms of daily necessities, it can be used as a wiping cloth, tablecloth, hat, kitchen water filter bag, filter residue bag, garbage packaging bag and other packaging materials, hot towel, padding, tea bag, coffee filter bag, etc.

Seaweed fiber

Seaweed is a polysaccharide extracted from brown algae in the ocean, which can be biodegraded into carbon dioxide and water under natural conditions. The seaweed sodium salt fiber obtained by spinning with its sodium salt as the main raw material has a dry strength similar to that of viscose, but its wet strength is very low and is not suitable for use as a traditional textile material. Seaweed sodium salt fiber is an eco-medical fiber that is non-toxic, has good insulation and absorption properties, and can promote wound healing. The nonwoven fabric made of it is widely used in wound dressing, medical gauze and other aspects.