|
Waterborne polyurethane (WPU) was developed in the 1950s, a new type of polymer, which is characterized by the wide range adjustable firmness, abrasion resistance, hydrolysis resistance, chemical resistance, good adhesion can be at a lower temperature formed, cured. Its main chain structure of a urethane (-NH-COO-) chain segment, the biggest advantage of the aqueous polyurethane is to be replaced with water and the organic solvent in the solvent-based polyurethane as a dispersing medium, and therefore has a non-toxic, non-polluting, noncombustible own characteristics such as energy conservation, safety, solvent-based polyurethane is also easy to operate, can be modified, film-forming temperature and low. With the growing environmental pressure increase, instead of solvent-based polyurethane waterborne polyurethane trend has become an indisputable fact. Although the performance of water-based polyurethane, but some areas of its application in the experimental research and development stage, there is a certain gap with solvent-based polyurethane. The content of the research is a water-based polyurethane synthetic leather. Preparative high resilient polyurethane synthetic leather microporous film only the solvent-based polyurethane, the wet process, although it is also useful for aqueous urethane made of the microporous structure, but more common in mechanical foaming method, and also not yet large industrial production. Therefore waterborne polyurethane chemical process high-elastic porous structure is a new issue, the scientific value and practical value. In this paper, the acetone method, the first waterborne polyurethane. The Fourier infrared scanner (FT-IR) of the WPU characterization, the results show that the product has the expected chemical structure; thermal gravimetric analysis (TGA) The thermal stability and characterization of the polymer; gel permeation chromatography (GPC) of the molecular weight analysis; tested and the solids content of the film, die amount (kg/cm2), tensile elongation (%), tensile strength (kg/cm2). The results show that the obtained aqueous polyurethane (WPU), good thermal stability and the molecular weight distribution exists between the soft and hard segments micro-phase separation, the mechanical strength of the film has reached the requirements of the aqueous polyurethane synthetic leather. Using the resulting WPU was added in accordance with a certain proportion of thickeners, leveling agents, wood powder additives, in the environment of the B sour bath, demulsification deposition. Do the mechanical strength of the membrane obtained in this way and WPU natural drying method contrast; to do scanning electron microscope (SEM) Characterization contrast with the the PU solvent wet process film prepared. The results showed that: thickeners and leveling agents contribute to an acid bath to obtain a uniform, flat film; by WPU acid bath demulsification method, the natural drying a prepared film mechanical properties, and found an acid bath demulsification Preparation when the film is sufficiently thin, transparent film can be obtained, its mechanical properties and the natural drying method or less; thick film If the acid bath prepared or add wood powder, compared with the opaque film, and its mechanical properties and the natural drying The dry method has a greater difference. SEM characterization of the surface and cross section of the the WPU acid bath demulsification method has a lot of microporous structure, which did not add wood powder richer relative to the porous structure of wood powder is added; However, no matter what kind of wet PU solvent Comparatively, the the microporous structure also obvious difference.
|