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Basic conditions for the raw material system used in spraying polyurea elastomer technology
(1) solvent-free, two-component, low-viscosity liquid at room temperature or under heating (<100 ° C);
(2) The difference in viscosity of each component should be as small as possible, generally not exceeding 300 mPa.s;
(3) the isocyanate component is generally an MDI-based prepolymer;
(4) each component has good compatibility, the mixing volume ratio of the reaction components is preferably 1:1, generally not more than 3:1;
(5) The curing speed should be as fast as possible, but the gel time should be greater than 5s, so as not to gel during impact mixing. Generally, the gel time is less than 60s, and the gel time should be shorter when the facade is sprayed to avoid sagging;
(6) A specially designed high-pressure impact mixing spray equipment is required.
(For the nature of the commonly used raw materials for SPUA technology and the design points of the formula, please refer to the book "Spray Polyurea Elastomer Technology" edited by Professor Huang Microwave)
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