How are non-woven fabrics made

Update:09 Jul 2021

Let's first understand how the fiber comes from. Natura […]

Let's first understand how the fiber comes from. Natural fibers exist in nature. Chemical fibers (including man-made fibers and synthetic fibers) are made by dissolving polymer compounds in a solvent into a spinning solution or high-temperature heating and melting into a melt, and then spin the solution or melt from the spinning solution. Extruded from the spinneret of the silk pump, the jetted stream cools and solidifies to form the nascent fiber, and the nascent fiber undergoes corresponding post-processing to form short fibers or filaments that can be used for spinning.

Woven fabrics are made by spinning fibers into yarns and then weaving or knitting the yarns into fabrics. Non-woven fabric does 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 all include fiber web formation and fiber web reinforcement.

"Fiber Laying", as the name implies, is to make fibers into a net. Common methods include dry-laid, wet-laid, spun-laid, melt-blown, and so on.

Dry-laid and wet-laid webs are more suitable for short fiber webs. Generally, the 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 from them. , Mix the various fiber components evenly, and make preparations before forming a net. The dry method generally involves combing and laying pre-processed 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 will form a fiber web.

Both spinning and meltblown webs are spinning methods using chemical fibers, and the fibers are directly laid into a web during the spinning process. Among them, the spinning solution or melt is sprayed from the spinneret to form filaments of a certain fineness after cooling and stretching, and forming a fiber web on the receiving device. The melt-blown web uses high-speed hot air to extremely stretch the fine stream ejected from the spinneret to form ultra-fine fibers, which are then gathered on the receiving device to form a fiber web. The diameter of the fibers formed by the melt-blown method is smaller, which is beneficial to improve the filtration efficiency.

Fiber mesh reinforcement

The fiber webs prepared by different methods have loose connections of internal fibers and low strength, which is difficult to meet the needs of use, so it needs to be reinforced. The commonly used reinforcement methods include chemical bonding, thermal bonding, and mechanical reinforcement.

Chemical bonding reinforcement method: The bonding agent is applied to the fiber web by dipping, spraying, printing, etc., and then heat treatment is carried out to evaporate the moisture and the bonding agent to solidify, thereby strengthening the fiber web to form a cloth.

Thermal bonding reinforcement method: Most high molecular polymers are thermoplastic, that is, they will melt and become sticky when heated to a certain temperature, and then resolidify after cooling. This principle can also be used to reinforce the fiber web. Commonly used are hot air bonding-using hot air to heat the fiber web to make it bonded and reinforced; hot rolling bonding-using a pair of heated steel rollers to heat the fiber web and apply a certain pressure to make the fiber web bonded and reinforced.

Mechanical reinforcement method: As the name implies, mechanical external force is applied to reinforce the fiber web. Commonly used are acupuncture, spunlace and so on. The needle punching method uses barbs with barbs to repeatedly puncture the fiber web, so that the fibers in the fiber web are intertwined and strengthened. Friends who have played poking music should be familiar with this method. The fluffy fiber mass can be poked into various shapes through acupuncture. The spunlace method uses high-speed and high-pressure fine water jets to spray on the fiber web to make the fibers intertwined and strengthened. It is similar to the needle punching method, except that it uses "water needles."

After completing fiber web formation and fiber web reinforcement, and then undergoing certain post-processing, such as drying, shaping, dyeing, printing, embossing, etc., the fiber officially becomes a non-woven fabric. According to 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, spunbonded non-woven fabrics (spun into a web), melt-blown non-woven fabrics, and heat-bonded non-woven fabrics. Non-woven fabrics, etc., non-woven fabrics made of different raw materials and production processes also have their own different characteristics.

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