Highly moisture permeable modified polyurethane and preparation method thereof

Abstract

The invention discloses highly moisture permeable modified polyurethane and a preparation method thereof. The invention solves the problem that dihydroxyalkyl polysiloxane and polyether polyol are separated from each other due to poor intersolubility by adopting a prepolymerization method. The highly moisture permeable polyurethane with an excellent mechanical property is prepared by the following steps: 1, prepolymer synthesis: namely carrying out reaction on polyisocyanates and dihydroxyalkyl polysiloxane different in proportion at 40-120 DEG C for a while by selecting different solvents according to different molecular weights of dihydroxyalkyl polysiloxane; and 2, synthesis of polyurethane: namely adding polyether polyol and a solvent in a stoichiometric ratio at 60-100 DEG C, gradually adding the prepolymer, controlling the adding speed, and obtaining a polyurethane product with proper viscosity by controlling the proportion of OH / NCO. The modified polyurethane can be applied to coating fabric surfaces in occasions with high waterproof, moisture permeable and mechanical performances and relatively high thermal stability.

Description

technical field [0001] The invention relates to a highly moisture-permeable modified polyurethane and a preparation method thereof, belonging to the technical field of improvement of fabric and leather surface coating materials. Background technique [0002] Since the 80s of last century, the American Gore Company proposed the synthesis method of waterproof and moisture-permeable film garment fabric polyurethane in the patent US 4532316, scientists and technicians from all over the world are looking for the synthesis method of highly waterproof, highly breathable and highly water-permeable polyurethane materials. . Since Yilgor et al. clarified the polyurethane microphase separation problem experimentally and theoretically, and proposed that the introduction of silicon-containing soft segments into polyurethane molecules can improve the mechanical and thermal properties of polyurethane materials, silicone-modified polyurethane has become a research hotspot. [0003] How...

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Problems solved by technology

[0003] However, organosilicon-modified polyurethane faces many difficult problems. First, the compatibility between organosilicon and polyols, which are necessary raw materials for the production of polyurethane, is poor, which leads to easy phase separation in the system; secondly, the poor reactivity of organosilicon is not conducive to Large-Scale Industrial Synthesis of Polyurethanes

Therefore, how to solve the poor solubility and low reactivity of silicone is an urgent problem to be solved in the silicone modified polyurethane industry.

[0004] Patent CN 102167798 A discloses an amino polysiloxane modified polyurethane. Although the production cost is reduced, due to the introduction of amino groups, urea groups with strong hydrogen bonds will be formed, which will affect the mechanical properties of polyurethane and cause polyurethane coating Hard; patent CN 102666655 A discloses a five-membered ring carbonate polysiloxane and diamine synthetic polyurethane for artificial leather coating materials, with good flexibility, friction resistance, high water resistance, etc., but the five-membered ring carbonate The production cost of ester polysiloxane is high, which is not conducive to large-scale application; patent CN 103421194 A discloses the synthesis of polyether polyurethane modified with long side chain organosilicon, and the obtained polyurethane has good water resistance, thermal performance, The production cost is cheap, but the mechanical properties of polyurethane materials are reduced due to the introduction of large side groups; patents CA 2419022 C and US 6794445 B2 disclose a polysiloxane-modified polyurethane coating with good flexibility, It is suitable for high-grade clothing fabrics; the patent US 4098742 discloses a polyurethane polysiloxane modified polyurethane material with high oil and water resistance, which can be used for glass, ceramics, masonry, wood, paper, metal, leather, especially textiles Surface coating of materials such as; Patent US 4962178 discloses a method for synthesizing a polyurethane polysiloxane-modified polyurethane material with high moisture permeability and flexibility, by first synthesizing an isocyanate-terminated polysiloxane prepolymer, Re-synthesis of polyurethane materials containing O-silyl-urethane crosslinked structure; Bao Tianyu of Shanghai Jiaotong University and others studied the research of polyether polyurethane modified with hydroxyfluorosilicone oil, and obtained a polyurethane material with high mechanical properties, thermal stability and high waterproof performance. However, due to the introduction of fluorine, the production cost increased, and corresponding environmental problems were caused; Rebeca et al. synthesized PDMS / PHMO block dihydroxyalkyl polysiloxane modified high moisture-permeable polyether polyurethane, obtained A polyurethane with a three-phase core-shell structure has excellent mechanical and thermal properties; Wang Wei and others from the School of Chemistry and Chemical Engineering, Donghua University synthesized a polyether-polysiloxane block blend polyurethane elastomer with very good properties. Excellent water resistance, the contact angle of water on the surface of PUS elastomer is increased from 71° to 101°

[0005] Although the above methods can improve or change some properties of polyurethane by modifying polyurethane with polysiloxane, they cannot improve the comprehensive performance of polyurethane, and the above methods are complicated in manufacturing process, high in industrial scale production cost, and not conducive to environmental protection requirements.

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