- Jan 03, 2018 -
The production technology of release paper for synthetic leather mainly includes three parts: original paper, release coating and embossing .
Release paper for synthetic leather has a high requirement for the basic paper . It not only requires high strength but also has strict requirements of heat resistance . The original paper generally weights over 125g/㎡,and its technical difficulty lies in the control of the thickness and heat resistance of the paper.The thickness is generally used softwood pulp and hardwood pulp ratio making way to control in heat resistance, heat addition agent in pulp to enhance the heat resistance of paper.
The coating layer can be divided into two major categories, namely, silicon and non silicon coatings. Silicon based materials include silicone resin and modified silicone resin with alkyd resin and acrylic resin. The non silicon release materials include chromium complex, methacrylic acid or fatty acid type polypropylene resin, polymethylolefin resin TPX and other special resins, amino alkyd resin, epoxy resin and so on.
Different types of coating have different characteristics, for example, silicone resin coating has excellent peel and heat resistance, chromium complex coating has poor solvent resistance, polypropylene coating has high gloss, but poor heat resistance. Different types of coating are also different in technology. Silicone coating is generally coated with roller or scraper, and the base paper must be primed first. The main purpose of the bottom coating is to improve the smoothness and the ability to resist the penetration of the silicon coating. Polypropylene resin and poly methylpentene resin coating mainly by extrusion coating method, it uses the paper can not be coated, the other added ingredients by extrusion coating machine feed feed coating, the release coating technology are related to control coating peel strength, and this is where the technical difficulties. Because this also involves the selection of the control agent for the stripping force and its effect on the other properties of the coating. The pattern on the paper is usually pressed by the embossing roll. The embossing process can be divided into the conventional embossing process and the special embossing process. The conventional embossing technology is also divided into the traditional embossing roller, the pressing technology and the embossing technology driven by gear transmission and roller. The special embossing technology mainly refers to the concave coating and embossing process, which is used to make clear and realistic high level off type paper. At present, only the Sappi Warren Company in the United States is used, and the off type coating used in this process is the embossing process of the electron beam curing resin.