Textile fibers include natural fibers such as cotton, hemp, wool, and silk, as well as chemical fibers such as viscose, polyester (polyester fiber), spandex, nylon, and acrylic.
From fibers to fabrics, there are generally two steps: one is that the fibers undergo a spinning process to form yarns, and the other is that the yarns undergo a weaving process to form fabrics. For example, woven fabrics (woven fabrics) and knitted fabrics commonly used in clothing are formed through two processes of spinning and weaving. Woven fabrics (woven fabrics) are two sets of mutually perpendicular yarns woven in a criss-cross pattern on a loom with a stable structure and flat surface. Knitted fabrics are formed by one or more groups of yarns that are looped together on a knitting machine according to a certain rule. The texture is soft and has great extensibility and elasticity.
In addition, some fabrics can be directly formed from fibers without spinning and weaving. This kind of fabric is what we usually call nonwoven fabrics. Nonwoven fabrics are oriented or randomly arranged fibers made by friction, cohesion, adhesion or a combination of these methods, and the connotation is "non-woven". Non-woven fabrics exist in the fabric in the form of fibers, while woven fabrics exist in the fabric in the form of yarns. This is also a main feature of non-woven fabrics that distinguish them from other fabrics. You can't get a single thread out.
What are the raw materials of non-woven fabrics?
As PetroChina and Sinopec began to build mask production lines, produce and sell masks, everyone gradually learned that masks and oil are inextricably linked. "From Oil to Mask" details the whole process from oil to mask step by step. Propylene can be obtained from petroleum distillation and cracking. Propylene can be polymerized to obtain polypropylene, and polypropylene can be further made into polypropylene fiber, which is what we usually call polypropylene. Polypropylene fiber (polypropylene) is the main fiber raw material for the production of non-woven fabrics, but it is not the only raw material. Polyester fiber (polyester), polyamide fiber (nylon), polyacrylonitrile fiber (acrylic fiber), viscose fiber, etc. Can be used to produce non-woven fabrics.
Of course, in addition to the above chemical fibers, natural fibers such as cotton, hemp, wool, and silk can also be used to produce non-woven fabrics. Some people often think of non-woven fabrics as chemical fiber products when they mention non-woven fabrics, which is actually a misunderstanding of non-woven fabrics. Like the fabrics we usually wear, non-woven fabrics are also divided into chemical fiber non-woven fabrics and natural fiber non-woven fabrics, but chemical fiber non-woven fabrics are more common. For example, the cotton towel in the picture below is a non-woven fabric made of natural fiber - cotton. (Here, I would like to remind everyone that not all products called "cotton towels" are made of "cotton" fibers. There are also some cotton towels on the market that are actually made of chemical fibers, but they are more tactile. It's just like cotton, you must look at the ingredients when you buy it)
How is non-woven fabric made?
Learn how fiber comes from. Natural fibers exist in nature, and chemical fibers (including man-made fibers and synthetic fibers) are produced by dissolving polymer compounds in a solvent into a spinning solution or heating and melting them at high temperature into a melt, and then the solution or melt is spun from the spinning solution or melt. It is extruded from the spinneret of the silk pump, and the sprayed thin stream is cooled and solidified to form primary fibers, and the primary fibers are then subjected to corresponding post-processing to form short fibers or filaments that can be used for spinning.
Woven cloth is made by spinning fibers into yarn, and then weaving the yarn into cloth by weaving or knitting. Nonwovens do not require spinning and weaving, so how does it turn fibers into cloth? There are many production processes for non-woven fabrics, and the processes are also different, but the core processes include fiber web formation and fiber web reinforcement.
"Fiber-laid", as the name implies, is to make fibers into a net shape. Commonly used are dry-laid, wet-laid, spun-laid, melt-blown and so on.
Dry-laid and wet-laid are more suitable for short fiber web formation. Generally, fiber raw materials need to be pretreated, such as tearing large fiber clusters and fiber blocks into small pieces to loosen them and remove impurities. , mix the various fiber components evenly and prepare for the formation of the web. The dry method is generally by carding and laying the pretreated fibers into a fiber web with a certain thickness. Wet-laid is to disperse short fibers in water containing chemical additives to form a suspension slurry, and then filter the water, and the fibers deposited on the filter screen will form a fiber web.
Both spin-forming and melt-blown web are spinning methods using chemical fibers, and fibers are directly laid into a web during the process of spinning and forming. The spinning into a web is that after the spinning solution or melt is ejected from the spinneret, it is cooled and stretched to form filaments of a certain fineness, and a fiber web is formed on the receiving device. The melt-blown web uses high-speed hot air to extremely stretch the thin stream ejected from the spinneret to form ultra-fine fibers, which are then gathered on the receiving device to form a fiber web. The fiber diameter formed by the melt blowing method is smaller, which is beneficial to improve the filtration efficiency.
fiber mesh reinforcement
The fiber web prepared by different methods has relatively loose connection of the internal fibers and low strength, which is difficult to meet the needs of use, so it needs to be reinforced. Commonly used reinforcement methods include chemical bonding, thermal bonding, and mechanical reinforcement.
Chemical adhesive reinforcement method: The adhesive is applied to the fiber web by dipping, spraying, printing, etc., and then heat treatment to evaporate the water and solidify the adhesive, so that the fiber web is reinforced to form a cloth.
Thermal bonding reinforcement method: Most of the high molecular polymers are thermoplastic, that is, they will melt and become sticky after heating to a certain temperature, and then solidify again after cooling. This principle can also be used to reinforce the fiber web. Commonly used are hot air bonding - heating the fiber web with hot air to make it bonded and reinforced; hot rolling bonding - heating the fiber web with a pair of heated steel rollers and applying a certain pressure to make the fiber web bonded and reinforced.
Mechanical reinforcement method: As the name suggests, it is to apply mechanical external force to reinforce the fiber web. Commonly used are acupuncture, spunlace and so on. Needle punching is to use barbs with barbs to repeatedly puncture the fiber web, so that the fibers in the fiber web are intertwined with each other and play a reinforcing role. Friends who have played Poke Poke should be familiar with this method. Through acupuncture, the fluffy fiber balls can be poke into various shapes. The spunlace method uses high-speed and high-pressure fine water jets onto the fiber web to entangle the fibers and reinforce each other.
After the fiber is formed into a web, the fiber web is reinforced, and after certain post-processing, such as drying, shaping, dyeing, printing, embossing, etc., the fiber officially becomes a non-woven fabric. According to the different web-forming and reinforcement processes, non-woven fabrics can be divided into many types, such as spunlace non-woven fabrics, needle-punched non-woven fabrics, spunbond non-woven fabrics (spun-forming non-woven fabrics), melt-blown non-woven fabrics, heat-sealed non-woven fabrics, and heat-sealed non-woven fabrics. Non-woven fabrics, etc., non-woven fabrics made of different raw materials and production processes also have different characteristics.
What are the uses of non-woven fabrics?
Compared with other textile fabrics, non-woven fabrics have a short process flow, fast production rate, high output and low cost. Therefore, non-woven fabrics are widely used, and their products can be seen everywhere, which can be said to be closely related to our daily life.
Many disposable hygiene products used in our daily life use non-woven fabrics, such as disposable bed sheets, quilt covers, pillowcases, disposable sleeping bags, disposable underwear, compressed towels, facial mask paper, wet wipes, cotton soft towels, sanitary napkins, diapers Wait. Surgical gowns, isolation gowns, masks, bandages, dressings, dressing materials, etc. in the medical industry are also inseparable from non-woven fabrics. In addition, wall coverings, carpets, storage boxes, vacuum cleaner filter bags, heat insulation pads, shopping bags, clothing dust covers, etc. for home use, floor mats in cars, roof fabrics, door linings, filter fabrics for filters , Activated carbon packaging, seat covers, sound insulation and shock absorption felts, rear window sills, etc. are also widely used non-woven fabrics.
It is believed that with the continuous innovation of non-woven fiber raw materials, production processes and equipment, more and more non-woven products with excellent performance will appear in our lives to meet our diverse needs. There is also non woven fabric slitting machine at SUNTECH. If you have interest in it, you can take a look with a simple click.