A room temperature curing ultra-low temperature epoxy sealant and preparation method thereof

Abstract

The invention discloses room temperature curing ultralow temperature epoxy sealant and a preparation method thereof. The epoxy sealant comprises 40-60 parts of polyurethane modified bisphenol S-type glycidyl ether epoxy resin, 40-60 parts of 680 epoxy resin, 20-33 parts of alicyclic amine curing agent and 10-30 parts of T-31 curing agent. The preparation method comprises the steps that firstly, polyester dibasic alcohol and / or polyether dibasic alcohol are / is used for reacting with isocyanate, so that polyurethane prepolymer with ends sealed by the isocyanate is obtained, and then the polyurethane prepolymer with the ends sealed by the isocyanate is used for reacting with bisphenol S-type glycidyl ether epoxy resin, so that the polyurethane modified bisphenol S-type glycidyl ether epoxy resin is obtained. The minimum operating temperature of the prepared epoxy sealant is 20K, the sealant is cured at the room temperature, the bonding strength at the liquid nitrogen temperature is larger than 15 MPa, the leakage under the 20K environment is less than 10-11 Pa.m3 / s, and the good low temperature bonding and sealing performance is achieved; in addition, the sealant contains no thinner, the problem that micromolecules volatilize to cause pollution does not exist, and the low temperature bonding and sealing requirements of precision components and parts can be satisfied.

Description

technical field [0001] The invention relates to an epoxy sealant and a preparation method thereof, in particular to a room temperature curing ultra-low temperature epoxy sealant and a preparation method thereof. Background technique [0002] With the development of aerospace, superconducting technology, national defense industry, etc., the demand for adhesives used in ultra-low temperature (90K and below) environments is increasing. In the aerospace and national defense industry, some precision devices need to work at the temperature of liquid helium and obtain good sealing performance through bonding, but due to the limitations of the bonding material, size, precision, and process conditions, the devices cannot be heated, and need to be heated at room temperature. Therefore, new requirements are put forward for ultra-low temperature adhesives. [0003] At present, the most researched is the ultra-low temperature adhesive, and the DW series adhesive developed by Shanghai Sy...

AI Technical Summary

Problems solved by technology

The low-temperature glue only uses diethylenetriamine as a curing agent, which is highly toxic and has been banned in developed countries; the molecular chain of diethylenetriamine is short, so the density of active cross-linking points is high, and the cross-linked product obtained by curing has poor toughness. The paper discloses the performance of the adhesive at the temperature of liquid nitrogen. When the temperature is further lowered, that is, when the use temperature drops to 20K, its low-temperature performance may not meet the requirements; in this paper, no data related to sealing are given, only from the viscosity of the adhesive. It is not sufficient to judge that it has good low-temperature sealing performance due to its high bonding strength at low and low temperatures. The shrinkage and molecular chain freezing during the cooling process may cause leakage, but the impact on the strength may not be obvious; moreover, Diethylenetriamine is used as a curing agent, which releases heat rapidly and can be quickly cured at room temperature. In "Application and Technology of Epoxy Resin" (published in September 2002) pp. 117-118, edited by Sun Manling, under 25°C , 550ml of sample batching temperature can reach 250 ℃, poor process performance in engineering

[0006] To sum up, the current room temperature curing ultra-low temperature adhesives have high viscosity, long curing time or severe reaction exotherm, which are difficult to meet the application requirements of low temperature engineering for room temperature curing ultra-low temperature sealants. The preparation of room temperature curing ultra-low temperature epoxy sealants is beneficial Expand the application range of low-temperature adhesives, and improve the technical level of low-temperature fields such as aerospace, superconducting technology, and national defense industry