Nonwovens production process
nonwovens production methods are more, but basically including raw material preparation, into the network, fibre network reinforcement, finishing and winding five production processes. Raw material preparation includes fibre opening, mixing, impurity removal, oiling agent and antistatic agent, etc. It is a necessary preparation procedure to ensure the quality of the fibre network.
Netting is one of the important processing processes in nonwovens production. The quality of the fibre net directly affects the performance and application of nonwovens. There are three main methods of forming a web of nonwovens: dry method, wet method and polymer extrusion method. Fibre mesh reinforcement is an important process to make fibre mesh with a certain strength and form a nonwoven fabric structure. It plays a decisive role in product quality. The commonly used reinforcement methods include mechanical reinforcement, chemical reinforcement and thermal bonding reinforcement.
The finishing process after h includes drying, baking, finishing, calendering, embossing, coating, stacking, dyeing, printing, cutting, etc. The purpose is to improve the performance of the final product and add beauty.
Finally, the nonwovens are rolled as required.
Overview of dry nonwovens production i
Dry production is the earliest method used in nonwovens, and it still dominates in nonwovens production.
Preparation of fibre mesh production. The preparation of dry mesh production includes mixing, clearing and adding necessary oil. The mixing and clearing machines used in the production of nonwovens are mostly borrowed from the traditional equipment of cotton spinning or wool spinning in China, while there is some special equipment for the production of nonwovens with short processes in foreign countries.
1) mechanical (carding) netting: it is the preparation of the process of fibre processing into a single fibre composed of a thin network, for layering into a network or direct reinforcement of the fibre network. The fibre carding into a net is mainly completed on the carding machine. Carding machine including single tin, roller cylinder type, cover plate cylinder type three categories. The fibre processed by carding machine shows a unidirectional arrangement of the thin net, which can be strengthened directly or by laying and stacking the fibre net in a certain way. The layering method includes parallel, cross and other combination methods, but the fibre in the resulting fibre network is arranged in a single direction, so the strength of the finished product varies greatly in the vertical and horizontal direction. In order to reduce this difference, a special method can be used to make the fibres in the network to a certain degree of disorderly arrangement.
airflow netting: airflow netting is the use of airflow to transport fibre, to form a disorderly arrangement of fibre uniform fibre network. The fibres in the web are distributed in three directions, with little difference in strength between longitudinal and transverse. Its process is: fibre after opening loose, remove miscellaneous, mixed, feed into high-speed rotation of cylinder, further comb into a single fiber, and then under the combined action of centrifugal force and airflow in cylinder, fiber off from the sawtooth, by airflow evenly conveying, condensing in the screen curtain, the formation of fiber network.
1) mechanical reinforcement
a) acupuncture reinforcement. Acupuncture is the main reinforcement method in dry nonwovens. It is the use of external force, through the barb of the needle to wind fibres tangled into a felt-like fabric. Feed to the curtain of acupuncture machine fleecy fibril net feeds bedplate, the needle board that contains acupuncture needle makes up and down reciprocating motion, make the acupuncture needle that contains barb makes up and down acupuncture in fibre net. The barb movement that partial fibre is pricked is taken from the green face of fibre net into the net or net bottom, make fibre up and down intersperse, rise to consolidate the effect. The fibre mesh after needling is output by another pair of output rollers. In addition to one-way acupuncture, two-way acupuncture can be used to improve the surface quality of the product. In addition, also can carry on fancy acupuncture, make product surface produces the specific fancy effect. In acupuncture processing, acupuncture depth, acupuncture density, needle type and needle arrangement are the main factors that affect the quality of products. Needling method is mainly suitable for producing medium-thick nonwovens.
B) seam reinforcement. The edging method is to use the edging yarn (or the fibre bundle in the hook fibre net) to form a loop mechanism to reinforce the fibre net, yarn layer or non-textile material layer (such as foam, film, etc.), making it into the edging nonwoven fabric. In addition, it can also be woven into the base fabric (woven or sewn nonwovens) coil structure, so that it produces a loop effect and become a loop type nonwovens. The edging method can be divided into fibre net edging type, non-yarn edging type, loop type and yarn edging type. Sewn nonwovens are similar in appearance and feel to traditional textiles and are suitable for clothing, household and industrial use.
C) jet net method. Jet net method, also known as hydraulic jet method, is a late development of nonwoven technology, the use of high-pressure thin bundle of water action in (vertical spray) metal curtain net fibre network, make the fibre by gap hydraulic action and downward movement, so as to achieve the fibre between the tangles (similar to acupuncture), and make the fibre network reinforcement. The non-woven fabric processed by the jet method has the characteristics of soft feel, leavening, high moisture absorption and basically no fibre crumbs, etc. It is mainly used for sanitary materials, followed by industrial and civilian products.
2) chemical bonding reinforcement: chemical bonding reinforcement is a mesh reinforcement method with the longest application history and wider application in nonwovens production, but in recent years, the use proportion of this method is gradually decreasing. Chemical adhesion method is to use a variety of methods, the adhesive with emulsion or solution form, evenly distributed in the fibre network, after curing to reach the fibre network of mutual adhesion and make fibre network reinforcement. Chemical adhesion can be divided into dipping adhesion, foam adhesion, spraying adhesion, printing adhesion and solvent adhesion.