Preparation method of aromatic high solid content water-borne polyurethane

Abstract

The invention discloses a preparation method of aromatic high solid content water-borne polyurethane. The water-borne polyurethane which can be used for manufacturing synthetic leather and has aromatic high solid content of more than or equal to 50 % is obtained by using aromatic isocyanate as the raw material and adopting an interpenetrating network technology, a blocking technology and a post-crosslinking technology. The preparation method comprises the following steps: firstly, preparing water-borne polyurethane A comprising an active end group -NH2; then dispersing a polyurethane prepolymer B sealed by a -NCO end group in the polyurethane A, wherein due to small relative molecular mass and low body viscosity of the polyurethane B, the polyurethane B is very easy to disperse in the polyurethane A; and carrying out molecular-level compounding and interpenetrating on the polyurethane A and the polyurethane B to obtain high solid content water-borne polyurethane resin with concentration of more than or equal to 50 %. The molecular design and synthesis method provided by the invention not only breaks through the bottleneck on a aromatic high solid content water-borne polyurethane preparation technology and reduces cost, but also meets the requirements for technically reducing energy consumption and improving drying speed and physical property of a coating.

Description

technical field [0001] The invention belongs to the technical field of water-based polymer materials and synthetic leather manufacturing, and in particular relates to a preparation method of aromatic high-solid water-based polyurethane. Background technique [0002] my country is the world's largest producer and consumer of synthetic leather or PU leather. In 2011, there were more than 2,600 synthetic leather enterprises in the country, including more than 500 enterprises above designated size. The synthetic leather is mainly PVC leather. The synthetic output is 2.41 million tons, which is equivalent to 4.81 billion square meters. More than 70% of the total output. [0003] The pollution problem of the synthetic leather industry is also prominent. Solvent-based polyurethane resin is basically used in the traditional synthetic leather manufacturing process, and the volatilization of organic solvents in the slurry is the main source of environmental pollution. Usually, the ...

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Problems solved by technology

Some people also learn from the method of adding a large amount of acetone to reduce viscosity during prepolymerization, and then steaming out acetone under negative pressure after emulsification. However, since acetone and water easily form an azeotropic mixture, it is difficult to remove the water in the solvent, so that the recovered acetone cannot Recycling, increased process, equipment, energy consumption and cost, and the product has no market competitiveness