Partially blocked polyurethane curing agent and preparation method thereof

Abstract

The invention discloses a partially blocked polyurethane curing agent and a preparation method thereof. The preparation method mainly comprises the following steps that end-NCO isocyanate prepolymer is obtained from the addition reaction of diphenylmethane diisocyanate and low-molecular polyol in ester solvent, and then the end-NCO isocyanate prepolymer reacts with isocyanate sealant to form the curing agent. The partially blocked polyurethane curing agent has the following characteristics that: a) according to the calculation of NCO by weight, the blocked-NCO content is between 1.0 and 5.0 percent; b) the solid content by weight of the curing agent is 75+ / -2 percent, and the percentage content of the NCO by weight is between 12.0 and 13.0 percent (according to the calculation of the effective percentage of the NCO, the percentage content of the NCO including blocked NCO radicals); and c) the viscosity of the curing agent at 25 DEG C is between 1,500 and 2,500 mPa. s. The invention has the advantages of low toxicity, good storage stability, adjustable curing speed and the like.

Description

technical field

[0001] The invention relates to a polyurethane adhesive curing agent and a preparation method thereof, in particular to a partially closed polyurethane curing agent and a preparation method thereof. Background technique

[0002] Polyurethane curing agent is a synthetic material widely used in coatings, plastics, rubber, leather, fibers, adhesives and other fields. The production method of polyurethane curing agent at home and abroad usually adopts the reaction of toluene diisocyanate (TDI) and trimethylolpropane to generate TDI / TMP adduct. During the production process of this adduct, some free TDI units that do not participate in the reaction will remain. Free TDI is volatile, highly toxic in the gas phase, and the content of free toluene diisocyanate is too high. During the production and construction of the product, this volatile free monomer is very irritating to the human respiratory system, skin and eyes. , TDI vapor will damage human liver and kidney ...