Nonwoven fabrics are composed of oriented or random fibers. It is called fabric because of its appearance and certain properties. Simply, it is not interwoven and braided by yarns, but the fibers are directly bonded together by physical or chemical methods. The fibers used in the production of nonwoven fabrics are mainly polypropylene (PP) and polyester (PET), nylon (PA), viscose, acrylic, ethylene (HDPE), and vinyl (PVC). According to the application, nonwoven fabrics produced by non woven machine are divided into two categories: disposable type and durable type.
Nonwoven fabric production processes
1. Spunlace nonwoven fabric: The spunlace process is to spray high-pressure fine water flow onto one or more layers of fiber webs, so that the fibers are entangled with each other and the fiber webs are reinforced and have great strength.
2. Heat-bonded nonwoven fabric: Heat-bonded nonwoven fabric refers to adding fibrous or powdery hot-melt bonding reinforcement materials to the fiber web, and the fiber web is then heated, melted, cooled, and reinforced into cloth.
3. Pulp air-laid nonwoven fabric: Air-laid nonwoven fabrics can also be called clean paper or dry-laid nonwoven fabrics. It uses the air-laid technology to open the wood pulp fiberboard into a single fiber state, and then uses the air-laid method to condense the fibers on the web-forming curtain, and the fiber web is then reinforced into a cloth.
4. Wet-laid nonwoven fabric: Wet-laid nonwoven fabric is to open the fiber raw materials placed in the water medium into single fibers, and at the same time mix different fiber raw materials to make fiber suspension pulp, and the suspension pulp is transported to the web forming mechanism. The fibers are formed into a web in the wet state and then consolidated into a cloth.
5. Spunbond nonwoven fabric: Spunbond nonwoven fabric is formed after the polymer has been extruded and stretched to filaments. The filaments are laid into a web, and the web is then self-bonded, thermally bonded, chemically bonded. Bonding or mechanical reinforcement methods turn the web into a nonwoven fabric.
6. Melt-blown nonwoven fabric: The process of melt-blown nonwoven fabrics include polymer feeding, melt extrusion, fiber formation, fiber cooling, web formation and reinforcement.
7. Needle-punched nonwoven fabric: Needle-punched nonwoven fabric is a kind of dry-laid nonwoven fabric. Needle-punched nonwoven fabric uses the puncturing effect of a needle to reinforce the fluffy fiber web into cloth.
8. Stitch-bonded nonwoven fabrics: Stitch-bonded nonwoven fabric is a kind of dry-laid nonwoven fabrics. It uses warp-knitted coil structure to fabricate fiber webs, yarn layers, nonwoven materials (such as plastic sheets, plastic thin metal foils, etc.) or their combinations.
9. Hydrophilic nonwoven fabrics: mainly used in the production of medical and sanitary materials to achieve better hand feel and not scratch the skin. For example, sanitary napkins and sanitary pads use the hydrophilic function of hydrophilic nonwoven fabrics.
Characteristics of nonwoven fabrics
The nonwoven fabric has no warp and weft threads, so it is very convenient to cut and sew, and it is light and easy to shape. Nonwoven fabrics break through the traditional textile principles, and have the characteristics of short process flow, fast production rate, high output, low cost, wide application, and many sources of raw materials. It is less strong and durable than woven fabrics and cannot be cleaned like other fabrics. Because the fibers are arranged in a certain direction, it is easy to split at right angles. Thus, the improvement of the production method is mainly focused on the improvement of preventing splitting.
Classification of nonwoven fabrics
v Spunlace nonwoven fabric
Features:
1. Flexible entanglement, will not affect the original characteristics of the fiber, and will not damage the fiber.
2. The appearance is closer to traditional textiles.
3. High strength and low fluff.
4. High hygroscopicity, quick moisture absorption.
5. Soft hand feel and good drapability.
6. The appearance is varied.
7. The production process is long and covers a large area.
8. The equipment is complex, the energy consumption is large, and the water quality requirements are high.
Product application: medical curtains, surgical gowns, surgical cover cloths, medical dressing materials, wound dressings, medical gauze, aviation rags, clothing lining fabrics, coated fabrics, advanced rags in the electronics industry, cotton pads, wet wipes, mask wrapping materials, etc.
v Heat-sealed nonwoven fabric
Features: Surface-bonded hot-rolled surfaces are mostly smooth, and point-bonded hot-rolled are relatively fluffy.
Product application: production of baby diapers and women's sanitary napkin covering materials, ointment base cloth, clothing lining, masks, etc.
v Pulp airlaid nonwoven fabric
Features: good bulkiness, soft hand feeling, super hygroscopic performance.
Product application: medical hygiene materials, especially disposable hygiene products with high water absorption (such as diapers, sanitary napkins, wet wipes, wipes, etc.).
v Wet-laid nonwoven fabric
Features:
1. The production speed is high, which can reach 400m/min.
2. Can make full use of short fibers.
3. The uniformity of the fiber web of the product is good.
4. Large water consumption and high one-time investment.
Applications:
1. Special paper: dust/liquid filter paper, tea bags.
2. Industrial use: filters, insulating materials, sound-absorbing materials.
3. Medical use: medical backing, medical tape, surgical bag wrapping material.
4. Civil: wallpaper, etc.
v Spunbond nonwoven fabric
Features:
1. The web consists of continuous filaments.
2. Excellent tensile strength.
3. There are many changes in the process, and various methods can be used for reinforcement.
4. The filament fineness has a wide variation range.
Applications:
1. Polypropylene (PP): geotextiles, tufted carpet base fabrics, coated base fabrics, medical and health materials, covering materials for disposable products, etc.
2. Polyester (PET): filter material, lining material, tufted carpet base cloth, agricultural material, packaging material, etc.
v Melt-blown nonwoven fabric
Features:
1. The web consists of extremely fine shorter fibers.
2. The uniformity of the fiber web is good, and the hand feels soft.
3. Good filtration performance and liquid absorption performance.
4. The strength of the fiber web is poor.
Product application: filter materials, medical and health materials, clothing materials, battery separator materials, wiping materials.
v Needle punched nonwoven fabric
Features:
1. Flexible entanglement between fibers, with good dimensional stability and elasticity.
2. Good permeability and filtration performance.
3. Feel plump and fluffy.