Damp-heat aging resisting NDI-based polyurethane microporous elastomer and preparation method thereof

Abstract

The invention provides a damp-heat aging resisting NDI-based polyurethane microporous elastomer and a preparation method thereof. The NDI-based polyurethane microporous elastomer is prepared from a component A and a component B according to the mass ratio of 100:(2.3-9.6) through a reaction. The component A comprises polycarbonate modified polycaprolactone polyhydric alcohol, polyester polyol, biobased polyol, a polymerization inhibitor and diisocyanate. The component B comprises a chain extender, a cross-linking agent, a catalyst, a foam stabilizer and a foaming agent. The NDI-based polyurethane microporous elastomer has very good damp-heat aging resisting performance, and has good hydrolysis resistance, low-temperature flexibility and physical and mechanical properties, and the use requirement under tough weather conditions such as high temperature and high humidity can be completely met. The preparation method is short in technological process, easy to operate, low in process cost,high in production efficiency and suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of polyurethane materials, and in particular relates to an NDI-based polyurethane microporous elastomer resistant to damp heat aging and a preparation method thereof. Background technique [0002] NDI-based polyurethane materials, from the microstructure point of view, the molecular chain segment contains naphthalene ring structural units, the rigidity of the molecular chain is stronger than that of the benzene ring, and the macroscopic performance of NDI-based polyurethane microcellular elastomers has high stiffness and very good Excellent mechanical properties, the products prepared with it have very low heat generation due to intermolecular friction and excellent dynamic performance during reciprocating motion, and can be used as damping materials or components for rail transportation, automobiles, ships, special equipment, etc. field. NDI-based polyurethane materials are generally formed by polymerizing...

AI Technical Summary

Problems solved by technology

NDI-based polyurethane materials are generally formed by polymerizing polyester polyols with NDI and then extending the chain. However, since the polyester system contains a large number of ester groups, when exposed to the presence of water molecules, especially in high-temperature and high-humidity environments, Accelerates the aging rate of the material and seriously affects the service life of the product. If polyether polyol is used instead, or polyether and polyester are compounded, although the resistance to humidity and heat aging is alleviated, the mechanical strength is too low, which limits the use of the product

[0003] At present, most of the polyester polyols containing side groups or polyadipate-polyether copolyols or polyadipate and polyether are used to polymerize prepolymers to improve the water aging resistance of the prepared polyurethane materials. performance, but the polyurethane material prepared by polyester polyol containing side groups is selected. Due to the introduction of branched chains in the molecular chain, the mechanical properties of the material are greatly reduced, which limits its application range; Polyurethane materials prepared by compounding diacid and polyether, due to the large difference in polarity between polyester and polyether molecules, poor compatibility, resulting in low mechanical strength of the material, and limited improvement in moisture and heat aging resistance, and due to the viscosity of the prepolymer Larger, resulting in more complex molding process, which is not conducive to production operations

[0004] For example, Chinese patent application CN1982351A discloses a preparation method of NDI-based polyurethane microcellular elastomer. The method selects a single polyester polyol containing side groups. Although the hydrophobicity of the polyurethane polyol is improved to a certain extent, the molecular The introduction of side groups in the chain greatly increases the distance between molecules and reduces the force between molecules, resulting in a significant decline in mechanical properties and heat resistance. The maximum tensile strength is only 4.78MPa, which limits its scope of application.

[0005] Chinese patent application CN104650330A discloses a preparation method of polyester diol and microporous polyurethane elastomer. The method prepares a polyester polyol with a molecular weight Mn=500-4000 by mixing dibasic alcohol and dibasic acid. The alcohol is mixed with diols with ether bonds, side methyl groups, and straight chains. The prepared polyester polyols are then combined with NDI to synthesize prepolymers at 120-140°C, and react with chain extender components to obtain microporous elastomers. , similar to the Chinese patent application CN1982351A, the introduction of side groups and / or ether bonds reduces the mechanical properties, heat resistance and oil resistance of the material, and its tensile strength is only 4.6MPa, and it has only been tested for 30 days (720h ) after damp heat aging performance, the water resistance stability after being placed for 1000h is still uncertain

[0006] Chinese patent application CN105504212A discloses a method for preparing a polyurethane elastomer resistant to moisture and heat aging. In this method, polyester and polyether polytetrahydrofuran polyol are used to compound the co-block copolymer polyurethane elastomer. The humidity and heat aging performance is also not ideal. The change rate of tensile strength under the condition of / 93%RH / 7d reached 30%, and the compatibility between polyester and polyether was poor, and the viscosity of the prepared prepolymer was high. It was compounded with aromatic isocyanate and aliphatic isocyanate, although it was reduced It has a certain viscosity, but the reaction speed of the two isocyanates is different, and the compatibility of polyols is not good, and it is easy to tear, resulting in poor mechanical properties of the material, poor dynamic properties, and complicated preparation process

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