A process for producing two-layer transfer film leather using water-based polyurethane dry foaming technology

Abstract

The invention relates to the technical field of leather, and relates to a process for producing split transfer-film leather by virtue of a waterborne polyurethane dry-type foaming technology. The process comprises the following steps: (1) through a roll coater, applying a waterborne polyurethane back cover sizing agent containing foaming micro-spheres onto the surface of split leather (also called split crust leather) in a roll coating manner, and ironing and foaming with a roller-type ironing machine after drying so as to form a back cover foamed coating; (2) through a roller coater, applying a waterborne polyurethane foaming sizing agent onto the upper surface of the back cover foamed coating in a roll coating manner, and drying to form a middle foamed layer; and (3) through a coating machine, spraying a waterborne polyurethane surface sizing agent on the middle foamed layer, embossing and milling after drying so as to obtain the split transfer-film leather. The production process can replace a process of producing split transfer-film leather by virtue of a solvent method; and the process not only can eliminate pollution problems caused by the use of solvents but also can improve the sanitation property of the split transfer-film leather.

Description

technical field [0001] The invention relates to the technical field of leather, in particular to a process for producing two-layer film-transferring leather by using a water-based polyurethane dry foaming technology. Background technique [0002] The leather industry is a traditional industry with comprehensive advantages in our country. In the process of leather production, natural leather such as cowhide is relatively thick, and is usually cut into two or more layers. The layer with natural grain (the hairy side of the tanning raw material belt, which will be exposed after depilation) is processed into the top layer of natural leather after surface coating, and is mostly used for the processing of high-grade natural leather products. The split leather of the second layer and below (also known as the second layer of crust leather) has no natural grain, and its aesthetics and practicality are not as good as the natural top layer leather. In the past, it was usually made int...

AI Technical Summary

Problems solved by technology

The quality of the two-layer transfer film leather produced by this production method is good, but there are also the following problems: one, the wet-process solidified coating of solvent-based polyurethane is used as the bottom layer, and the wet-process solidified coating is made of solvent-based polyurethane (PU ) slurry, using a roller coater to coat the surface of the two-layer crust leather, and then enter the "H 2 O-DMF" coagulation bath, which solidifies PU to form a film with a microporous structure

However, DMF (dimethylformamide) is used as a solvent in this process, and the processing process will cause solvent pollution of DMF

Second, in the solvent-based wet coagulation process, water cannot completely replace the DMF in polyurethane, which will cause DMF residue in the product and eventually cause product safety problems

And this kind of product safety problem will restrict products from entering the high-end market amidst numerous technical barriers and trade barriers.