US 12,448,554 B2
Method of preparing environmentally-friendly water-resistant tannin-based wood adhesive
Xiaojian Zhou, Yunnan (CN)
Assigned to Southwest Forestry University, Kunming (CN)
Filed by Xiaojian Zhou, Yunnan (CN)
Filed on Dec. 26, 2022, as Appl. No. 18/146,392.
Claims priority of application No. 202210993654.3 (CN), filed on Aug. 18, 2022.
Prior Publication US 2023/0130576 A1, Apr. 27, 2023
Int. Cl. C09J 175/02 (2006.01); C09J 193/00 (2006.01); C09J 197/00 (2006.01)
CPC C09J 197/00 (2013.01) 4 Claims
 
1. A method of preparing a water-resistant tannin-based wood adhesive, comprising the steps of:
(a) adding tannin to an aqueous solution of epoxy chloropropane, resulting in a reactive aqueous solution;
(b) heating the reactive aqueous solution to a reaction temperature of 80° C.;
(c) after a predetermined period of time of reaction, adding 20 wt % NaOH aqueous solution to the reactive aqueous solution, resulting in a catalyzed reactive aqueous solution;
(d) maintaining the catalyzed reactive aqueous solution at 80° C. for three hours, resulting in an aqueous solution of epoxidized tannin;
(e) cooling the aqueous solution of epoxidized tannin to 20° C.;
(f) purifying the aqueous solution of epoxidized tannin by repeating the following sequence 2 to 4 times: diluting the aqueous solution of epoxidized tannin with absolute ethyl alcohol, conducting suction filtration with a suction filter, and performing rotary evaporation of the filtrate; and subsequently performing the sequence with acetone in place of the absolute ethyl alcohol, to obtain an epoxidized tannin;
(g) grafting triethylene tetramine to the epoxidized tannin, to graft copolymerize the epoxidized tannin; and
(h) deaminating the graft copolymerized epoxidized tannin with urea to obtain the water-resistant tannin-based wood adhesive.