The Basic Function of the Adhesive Lining
The fabric, which is deeply coated with thermoplastic high molecular compounds, and adhered with clothes fabrics under certain temperature and pressure, has certain adhesive power, and is taken as the clothes lining, is called as hot melt adhesive (adhesive lining for short).
The adhesive lining mainly includes the following functions:
1. It is used to reinforce and strengthen various types of clothing and various positions.
2. It is used to thicken the required positions of the clothing.
3. It is used to increase the elasticity and stiffness of the clothing, and improve the shape retention, the heat preservation, the draping property, and the three-dimensional sense of the clothing.
4. The hot melt adhesive lining also can be applied to shoe, cap and leather industries.
According to the coating methods, the adhesive linings can be divided into:
(1) Spreading Powder Lining
Spreading powder lining: the spread powder process is the simplest hot melt coating process. The method is that an engraved roll under a hopper is utilized to rotate with constant speed, the hot melt adhesive powder in the hopper is transferred to the base cloth surface, and the coating amount is controlled by changing the speed of the engraved roll or the cloth.
The spreading powder lining, with wide application, can be used as linings of various grades of fashions, fur leather shoes, caps and so on. The base fabrics, which are suitable for being processed into the spreading powder linings, include unwoven cloths and woven cloths with various thicknesses and gram weights. Hot melt adhesives such as EVA, EVAL, LDPE, PA, PES and HDPE and so on, can be used as processing raw materials of the spreading powder lining. The spreading powder lining with weaker coating evenness, is only applicable to the non-permanent adhesion without considering the washing-resistant performance, so the hot melt adhesives such as PA, PES and HDPE are not economical if processed by powder spread; similarly, the stability of dry-wet dimensions of the base fabric should be required according to the concrete use, but sometimes the requirement to the touch sense is high.
What the powder spreading method and its characteristics are?
The spreading powder lining is produced by the process that a powder spreader spreads the powdery hot melt adhesive onto the fabric, and then the powdery hot melt adhesive is melted, cooled and fixed by a far infrared heater. The powder amount of the given hot melt adhesive is controlled by means of the speed of a roller and the speed of the base fabric. The coating method is simple and convenient, but has weaker evenness. The adhesive lining, which is produced by the powder spreading method, is applicable to small areas for strengthening or temporary adhesion, and not suitable for being used as the main lining. Usually, the fineness of the hot melt adhesive powder used by the powder spreading method is between 180 and 360 (40-80 meshes or so), and low-end non-woven linings or linings for fur clothes or taping (inlaying) linings usually adopt the coating method.
(2) Power Point Method
The core of the powder point lining processing equipment is a powder point transfer device consisting of a hot roller, an engraved roll and a hopper. The engraved roll is provided with small semi-spherical pits which are orderly arranged, the hot melt adhesive powder in the hopper is scraped into the rotating pits of the engraved roll by a blade under the hopper, heated to encounter the foundation fabric heated by the hot roller, and transferred onto the foundation fabric in accordance with the arrangement and the shapes of the small pits of the engraved roll. The firm transfer is assured by infrared drying, and the surfaces of various powder points are melted into a whole to avoid the powder from falling. Almost all the hot melt adhesives can be used to process the powder point lining, and the base fabrics, which are most suitable to process the powder point lining, are various specifications of purified cotton, polyester cotton and rayon woven fabrics; in addition knitted fabrics and weft insertion warp knitting fabrics can also be used as the base fabrics of the powder point lining, but are more difficult than the woven fabrics.
The hot melt adhesives of the powder point lining have various specifications of arrangements on the basic fabric, including regular point distribution and irregular point distribution. Mesh factories are also not different, mainly including 11, 14, 17, 22, 28, 33 and 35 meshes, wherein the distributions less than 22 meshes (including 22 meshes) are mostly used to process the linings for garments, the HDPE or PES hot melt adhesives are usually adopted, and the coating amount is between 25 and 30g/㎡; in addition, 22-mesh and 35-mesh distributions can be irregular and are mainly used for soft powder point linings, for example: the thin color lining that is popular abroad now, usually adopts the hot melt adhesives with low melting point and dry washing resistance, and the coating amount is between 10 and 14g/㎡.  
The powder point lining with larger processing difficulty, is easy to cause quality problems; and the hot melt adhesive, with few impurities and large cohesion force, can show highest peeling strength and good washing-resistant performance compared with the linings processed by other processes. It is inevitable that the powder point lining has the disadvantages that: the powder point lining has weaker touch sense and large limitation to the foundation fabric because the powder point lining is processed under high temperature and bigger tension, and can not processed non-woven linings and chemical fiber fabrics with large heat contractibility.
With wide application, the powder point lining, which can be adopted by almost all costumes, has extremely applicability to other various clothing industries. It can be used for false adhesion, and permanent adhesion; especially in China, various standard clothing, casual wears for men and women and shirts are all using the powder point lining in a large quantity, so the quality indicator requirement to the powder point lining is also high. The main examination indicators for the powder point lining include: coating amount, coating evenness, peeling strength, washing-resistant performance and dry-wet dimension stability performance. Certainly, the feasible indicator requirement should be put forward according to the actual use, which is most economic and effective.
(3) Paste Dot Method
The process principle of the paste-dot lining is similar to that of the rotary screen printing. The core of the equipment is a paste nosedive; the equipment mainly includes a metal rotary screen; the holes is regularly or irregularly arranged on the metal rotary screen; a majority of the holes are round and the rest holes are in other shapes; the density and the diameters of the holes have certain specifications; a metal hollow pipe and a scraper are arranged in the round screen; the hot melt adhesive is blended into the paste, pumped into the hollow pipe by a feed pump, transferred onto the foundation fabric by means of the scraper and the round screen holes, and finally dried, melted and fixed.
The key of paste-dot lining processing lies in the processing of the hot melt adhesive paste; the paste contains various addition agents in certain proportion besides the hot melt adhesive as the main component, with the purpose of being conveniently transferred.
The hot melt adhesive of paste dots is coated in a paste mode. The hot melt adhesive suitable for the paste is the hot melt adhesive with certain hydrophilic performance; usually the melt index is higher if the hydrophilic performance of the hot melt adhesive is ultrastrong, and the cohesion force is consequentially smaller if the viscosity, the molecular weight and the melting point are smaller; especially the certain proportion of addition agent substance exists in the hot melt adhesive paste, which will also affect the cohesion force of the hot melt lining, so the peeling strength after the paste-dot lining is adhered to the clothes fabric can not compare with that of the powder point lining.
(4) Double-dot Coating
Powder double-layer method: the method is the combination of the paste dot method and the powder spreading method. Firstly, the round screen is used to coat paste dots, then a layer of hot melt adhesive powder is spread by the powder spread method without need to wait the paste dots to be dry, and the powder is firmly adhered to the paste dots through a vibrator. The powder, which is not adhered, is sucked by a suction nozzle and is recovered for reutilization. Many granular adhesive points adhered to the paste dots are dried, melted and sintered to form the double-layer coating.
What the double-dot method and its characteristics are?
The double-dot method can be divided into a double powder point method, a double paste-dot method and a paste-dot powder spreading method. The latter has a more mature technology and is a coating method which combines the paste-dot method and the powder spread method. The method is that upper-layer and lower-layer hot melt adhesives are formed on the foundation fabric, usually the lower-layer (foundation layer) paste dots are PA adhesive and crosslinking acrylic resin, and the upper-layer (covering layer) are PE or PA hot melt adhesives. Two hot melt adhesives with difference performances are selected and compounded into point shapes to ensure that the foundation layer is adhered with the foundation fabric, so as to achieve the ideal adhesion effect, obtain good touch sense and have wider fusing conditions. The method is applicable to the production of adhesive linings for high-class garments.