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CN-121991580-A - High-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating and preparation process thereof

CN121991580ACN 121991580 ACN121991580 ACN 121991580ACN-121991580-A

Abstract

The invention relates to the technical field of high polymer materials and coatings thereof, and discloses a high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating and a preparation process thereof. The coating is prepared by mixing an isocyanate-terminated polysilazane prepolymer and an amino component in proportion. The method is characterized in that a sequential gradient curing process is adopted to construct a deep interpenetrating network structure in a system, so that molecular-level hybridization of an inorganic phase and an organic phase is realized. By adopting the technical scheme, the invention solves the bottleneck that polysilazane has high brittleness and polyurea has poor heat resistance, improves the strength, the heat stability and the hydrophobic self-cleaning performance of the coating, solves the problem of thick coating cracking, ensures that the coating has excellent adhesive force and weather resistance, and is suitable for the fields of aerospace, petrochemical corrosion resistance and the like.

Inventors

  • ZHANG WENMEI
  • SI ZONGFEI

Assignees

  • 扬州市钦源医药科技有限公司
  • 江苏扬州化学工业园区综合服务中心

Dates

Publication Date
20260508
Application Date
20260321

Claims (10)

  1. 1. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating is characterized by being prepared by mixing an isocyanate-terminated polysilazane prepolymer component and an amino component according to a mass ratio of 1:0.8-1:1.5.
  2. 2. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 1, wherein the component A comprises the following components in parts by weight: 30 to 50 parts of isocyanate monomer; 15 to 25 parts of hydroxyl-terminated polysilazane; 10 to 20 parts of a reactive diluent; 0.5 to 1.5 parts of antioxidant; 0.2 to 0.8 part of defoaming agent.
  3. 3. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 1, wherein the component B comprises the following components in parts by weight: 40 to 60 parts of amino-terminated polyether; 10 to 20 parts of amino-terminated polysilazane; 15 to 25 parts of amine chain extender; 5 to 12 parts of nano self-cleaning functional auxiliary agent; 1 to 3 parts of a coupling agent; 0.5 to 1.2 parts of ultraviolet absorber.
  4. 4. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 2, wherein the isocyanate monomer is at least one selected from diphenylmethane diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate, and preferably the isocyanate monomer is modified diphenylmethane diisocyanate subjected to liquefaction treatment.
  5. 5. The high-strength, temperature-resistant, self-cleaning polysilazane polyurea hybrid coating of claim 2, wherein the hydroxyl-terminated polysilazane is an inorganic-organic hybrid polymer having a Si-H bond and a Si-N bond backbone and has a hydroxyl group at a molecular terminal capable of reacting with an isocyanate group, and wherein the hydroxyl-terminated polysilazane has a urethanization reaction with an isocyanate group in the isocyanate monomer through its terminal hydroxyl group, thereby anchoring a polysilazane segment to an isocyanate prepolymer backbone.
  6. 6. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 2, wherein the reactive diluent is at least one selected from dimethyl carbonate, butyl acetate and propylene glycol methyl ether acetate, the water content of the reactive diluent is less than 0.01%, the component A further comprises a composite catalyst, the composite catalyst consists of an organotin catalyst and a tertiary amine catalyst, and the total mass fraction of the composite catalyst is 0.05-0.15% of the total mass of the component A.
  7. 7. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 3, wherein the amino-terminated polyether is selected from amino-terminated polyoxypropylene ether with a functionality of 2 or 3, or a grading system formed by mixing amino-terminated polyether and amino-terminated polyether according to a mass ratio of 1:3.
  8. 8. A high strength, temperature resistant, self cleaning polysilazane polyurea hybrid coating according to claim 3, wherein the amino terminated polysilazane structure contains repeating silazane units and the molecular chain ends have primary or secondary amino groups.
  9. 9. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 3, wherein the nano self-cleaning functional auxiliary agent is nano silicon dioxide or nano aluminum oxide subjected to surface modification.
  10. 10. The high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating according to claim 9 is characterized in that a perfluoroalkyl silane coupling agent is adopted for surface modification, so that the surface of the nanoparticle has fluorocarbon chain segments with low surface energy, and the nano self-cleaning functional auxiliary agent is subjected to ultrasonic pre-dispersion treatment in absolute ethyl alcohol before being added.

Description

High-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating and preparation process thereof Technical Field The invention belongs to the technical field of high polymer materials and coatings thereof, and particularly relates to a high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating and a preparation process thereof. Background The polysilazane coating is formed by alternately forming Si-N bonds in a molecular main chain, so that complex hydrolysis, condensation and oxidation reactions can occur in the heat curing or moisture curing process, and finally the polysilazane coating is converted into an inorganic-organic hybrid network with a silicon dioxide-like structure. This unique conversion mechanism imparts extremely high surface hardness, excellent oxidation resistance, and extremely low surface energy to the coating. Polyurea systems are characterized by the extremely rapid chemical reaction of their isocyanate component with the amino-terminated compound, which forms a large number of highly polar urea linkages in the molecular chain. These urea linkages form physical cross-links through strong intermolecular hydrogen bonding, thereby imparting extremely excellent tensile strength, impact toughness, and good adaptability to deformation of the substrate to the polyurea coating. However, polysilazane undergoes severe molecular chain rearrangement and chemical shrinkage during curing to form a high-hardness inorganic network, and the side effect caused by the high crosslinking density is a great internal stress accumulation. Due to the lack of sufficient soft segments to buffer stress, polysilazane coatings exhibit a brittle tendency, not only to very susceptibility to spontaneous microcracking or even large area spalling as the coating thickens, but also to brittle fracture under alternating cold and hot impact conditions due to mismatch with the coefficient of expansion of the substrate. The single polyurea coating is an organic polymer system in nature, and under the environment of continuous high temperature or strong ultraviolet irradiation, the organic chain segments in the molecular chain are easy to be subjected to thermooxidative degradation and thermosoftening, so that the mechanical strength of the coating is enabled to fall down in a cliff-shaped manner in a high temperature range, the surface energy of the coating is higher, and a long-acting self-cleaning function is difficult to realize. When attempting to combine polysilazane with polyurea by means of physical blending, severe microscopic phase separation is extremely easily induced during film formation due to the great difference in chemical polarity, molecular weight distribution and curing kinetics of the two. The phase separation causes extremely weak interfacial bonding force between the inorganic phase and the organic phase, so that the coating loses the original high elastic toughness of polyurea and cannot fully exert the temperature-resistant hardness of polysilazane. Disclosure of Invention Aiming at the technical problems of large solidification brittleness, easy cracking and poor thick coating performance of a single polysilazane coating in the background art, the invention provides the high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating and the preparation process thereof, and aims to overcome the defects of greatly reduced strength, long-acting heat resistance and insufficient ageing resistance of the single polyurea coating in a high-temperature environment, and further overcome the systematic contradiction that the microscopic phase separation is serious, the interface binding force is weak and the performance cannot realize synergistic enhancement caused by simple physical blending of polysilazane and polyurea. The invention constructs a deep interpenetrating network structure in a double-component system of polysilazane and polyurea through a molecular design means, combines a specific sequential gradient curing process, realizes high hybridization of an inorganic phase and an organic phase on a molecular level, and improves the comprehensive mechanical strength of a coating, the stability at extreme temperature and a long-acting hydrophobic self-cleaning function. In order to achieve the aim of the invention, the high-strength temperature-resistant self-cleaning polysilazane polyurea hybrid coating provided by the invention is prepared by mixing a component A and a component B according to the mass ratio of 1:0.8 to 1:1.5. The A component is isocyanate terminated polysilazane prepolymer component, and the B component is amino component. The component A specifically comprises, by mass, 30 to 50 parts of isocyanate monomer, 15 to 25 parts of hydroxyl-terminated polysilazane, 10 to 20 parts of reactive diluent, 0.5 to 1.5 parts of antioxidant and 0.2 to 0.8 part of defoamer. The isocyanate monomer is selected from one or more of