Patent ID: 11879071
Assignee: JIANGNAN UNIVERSITY
Field: Basic materials chemistry (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A method for preparing a low-viscosity thermosetting starch adhesive for particleboards, wherein the composition of the starch adhesive for particleboards comprises: (in parts by mass) 100 parts starch, 150-400 parts water, 3-15 parts concentrated hydrochloric acid, 8-20 parts sodium hydroxide solution, 2-8 parts graft monomer, 0.5-2 parts initiator, 1-3 parts emulsifier, and 5-15 parts crosslinking monomer;
wherein the graft monomer is itaconic acid; the crosslinking monomer is one or both of N-hydroxyethyl acrylamide and acetoxyethyl methacrylate; and
the method comprises the following steps:
(1) blending the starch and water into starch slurry with a mass ratio of 20-45% on a dry basis of starch, and stirring evenly;
(2) adjusting the temperature of the starch slurry to 50-75° C., adding 0.5-0.7 mol/L hydrochloric acid for acid hydrolysis for 1.5-3 hours, and then adding the sodium hydroxide solution to adjust the pH of the starch slurry to 3-5;
(3) adjusting the temperature of the acid-hydrolyzed starch slurry to 80-90° C. at a rate of 1-2° C./minutes, and pre-gelatinizing for 20-50 minutes;
(4) taking the initiator that accounts for 50%-80% of the total mass of the initiator and adding water to prepare an initiator solution with a mass concentration of 1%-2%; taking the emulsifier and adding water to prepare an emulsifier solution with a mass concentration of 3%-7% emulsifier; taking the graft monomer and adding water to prepare a solution of 8%-12% graft monomer in the emulsifier solution, adding the crosslinking monomer and mixing evenly;
(5) directly adding the initiator solution and emulsifier solution prepared in step (4) into a starch reaction system obtained after the pre-gelatinization in step (3), and dripping a mixed solution of the graft monomer and the crosslinking monomer into the starch reaction system obtained after pre-gelatinization in step (3) at a uniform speed within 80-100 minutes; after the dropwise addition is completed, adding a reformulated initiator solution to form a mixture and keeping the temperature of the mixture at 80-90° C. for 80-100 minutes to form a modified emulsion, wherein the reformulated initiator solution is prepared by adding water to the remaining initiator not used in step (4) to provide a mass concentration of 1%-2% initiator; and
(6) adjusting the pH of the modified emulsion and then cooling the modified emulsion to 30-50° C. to obtain the starch adhesive.