Production technology of PU synthetic leather

Production technology of PU synthetic leather

With the development of plastic varieties and processing technology, a variety of series products of artificial leather have been formed. In addition to PVC, polyamide, polyurethane and polyolefin are used as coating materials. There are many kinds of base fabrics, such as plain cloth, canvas, knitted cloth, fleece cloth, non-woven fabric, etc. The production of synthetic leather with different varieties and colors is also different from the coating and gelation methods of base coat, and the finishing process, such as the order of embossing, printing, surface treatment, and the composition of surface treatment agents.

Production: including base cloth treatment, rubber preparation, coating, laminating, gelatinization, surface treatment, embossing, cooling, coiling and other processes. There are four main production methods.

Direct coating method: the rubber is directly coated with a scraper on the pretreated base cloth, then the plasticizer is used for gelation and plasticization, and then finished by the process of embossing, cooling and so on. This method can be used to produce various kinds of cloth based common artificial leather, film coated artificial leather and foamed artificial leather.

Transfer coating method: also known as indirect coating method. The paste is coated with a reverse roller or scraper on the carrier (strip or stainless steel strip), and then after being gelatinized, the cloth is then compounded on the gelatinized layer without tension, then plasticized, cooled and stripped from the carrier, then postprocessing is performed to obtain the finished product. This method is suitable for producing knitted fabric or non-woven fabric based foam artificial leather and ordinary artificial leather.

Calendering and sticking method: according to the formula requirements, the resin, plasticizer and other compounding agents are measured and put into the kneader to mix evenly, and then they are sent to the three roll or four roll calender after being refined by internal mixer, open mixer or extruder (see plastic mechanical calendering to form a thin film with the required thickness and width, which is bonded with the pre heated base cloth, and then the finished product is obtained by embossing and cooling. This method can produce various kinds of artificial leather with different cloth bases. In order to improve the adhesion effect between the base cloth and the film, a layer of adhesive is usually applied on the base cloth first.

Extrusion sticking method: the resin, plasticizer and other compounding agents are evenly mixed in the kneading machine. After refining, the film is extruded into a certain thickness and width by the extruder, and then it is bonded with the preheated base cloth on the three roll shaping machine. After preheating, sticking film, embossing and cooling, the product is obtained. This method is used to manufacture thick products, such as floor leather, conveyor belt, etc.