Method for preparing acrylate laminating adhesive by soap-free emulsion polymerization

A method for preparing an acrylate laminating adhesive by soap-free emulsion polymerization, comprising steps of

• (1) adding acrylic acid, ethanol, a RAFT chain transfer agent, and a first initiator into a reactor, then vacuumizing the reactor, introducing a nitrogen into the reactor, and performing a reaction at 60-65° C. for 24-72 h;
• (2) adding butyl acrylate and a second initiator into the reactor of step (1), vacuumizing the reactor, introducing nitrogen into the reactor, performing a reaction at 60-65° C. for 12-72 h, and then vacuumizing the reactor at 60° C. to remove ethanol, to obtain an acrylic block oligomer;
• (3) adding the acrylic block oligomer obtained in step (2), deionized water, an acrylate monomer, a hydroxyl-containing monomer, a carboxylic acid monomer, a chain transfer agent and a third initiator into an emulsification kettle, and performing an emulsification under stirring, to obtain a monomer pre-emulsion;
• (4) adding deionized water into a reaction kettle and heating to 80-82° C., adding a part of the monomer pre-emulsion obtained in step (3) and a fourth initiator into the reaction kettle, and performing a reaction for 20-30 min;
• then adding dropwise a remaining part of the monomer pre-emulsion to the reaction kettle within 2-4 h, then keeping a first resulting mixture at a temperature of 80-82° C. for 1 h, and then cooling to 65° C., and adding dropwise an aqueous solution of a reducing agent thereto for a post-treatment;
• then cooling a second resulting mixture to a temperature of 45° C. or lower, adding aqueous ammonia thereto to adjust a pH value to be 7-8, and finally adding a wetting agent and a defoaming agent thereto, stirring to be uniform, and filtering, to obtain an acrylate laminating adhesive crude emulsion;
• and
• (5) mixing the acrylate laminating adhesive crude emulsion obtained in step (4) and an aqueous curing agent to be uniform by stirring, to obtain the acrylate laminating adhesive.