Patent ID: 11965076
Assignee: LANZHOU INSTITUTE OF CHEMICAL PHYSICS, CAS
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 6:
7. A method for preparing a double-layer self-healing PU film, wherein the double-layer self-healing PU film comprises a soft-layer PU film arranged on a surface of a matrix; and
a hard-layer PU film arranged on a surface of the soft-layer PU film,
wherein the soft-layer PU film is prepared from a PU material I of a self-healing PU material; and the hard-layer PU film is prepared from a PU material II of the self-healing PU material;
the PU material I is prepared from raw materials comprising a polyol substrate I, a diisocyanate I, a tin-based catalyst I, a T-type chain extender, and a chain extender I at a molar ratio of (10-20): (20-40):(1-3):(2-8):(8-12);
the PU material II is prepared from raw materials comprising a polyol substrate II, a diisocyanate II, a tin-based catalyst II, the T-type chain extender, a metal salt, and a chain extender II at a molar ratio of (10-20):(20-40):(1-3):(5-10):(2.5-10):(5-10); a metal ion in the metal salt being one or more selected from the group consisting of Zn2+, Cu2+, and Fe3+;
the polyol substrate I and the polyol substrate II each are independently selected from the group consisting of a polyester polyol and a polyether polyol; and
the T-type chain extender has a structure represented by formula A:, , and
the method comprises the following steps:
subjecting a feed solution comprising the polyol substrate I, the diisocyanate I, and the tin-based catalyst I to prepolymerization I to obtain a prepolymerization product system I; mixing the prepolymerization product system I with a solution of the T-type chain extender to obtain a first mixture, and subjecting the first mixture to chain extension I-I to obtain a chain extension product system I-I; and mixing the chain extension product system I-I with the chain extender I to obtain a second mixture, and subjecting the second mixture to chain extension I-II to obtain the PU material I;
subjecting a feed solution comprising the polyol substrate II, the diisocyanate II, and the tin-based catalyst II to prepolymerization II to obtain a prepolymerization product system II; mixing the prepolymerization product system II with a solution of the T-type chain extender to obtain a third mixture, and subjecting the third mixture to chain extension II-I to obtain a chain extension product system II-I; mixing the chain extension product system II-I with a solution of the metal salt to obtain a fourth mixture, and subjecting the fourth mixture to coordination to obtain a coordination product system; and mixing the coordination product system with the chain extender II to obtain a fifth mixture, and subjecting the fifth mixture to chain extension II-II to obtain the PU material II; and
coating the PU material I onto the surface of the matrix to obtain a PU material I film, and subjecting the PU material I film to drying I to obtain the soft-layer PU film; and coating the PU material II onto the surface of the soft-layer PU film to obtain a PU material II film, and subjecting the PU material II film to drying II to obtain the hard-layer PU film, thereby forming the double-layer self-healing PU film on the surface of the matrix.