The Preparation Of Melamine Curing Agent And Its Effect On The Properties Of Polyurethane Elastomer

Polyurethane elastomer has excellent wear resistance,high resilience,high elongation at break,etc.has been used in various fields of engineering and construction.But with a low temperature tolerance make this material is easily burning when they are in fire.In order to solve this problem,this thesis designs and synthesizes a type of melamine polyurethane curing agent,the high temperature triazine ring structure in melamine is introduced into polyurethane elastomer,Which increases the flame retardant of polyurethane elastomer.This design is different from adding flame retardants in the polyurethane elastomer.The addition type flame retardant is dispersed in the elastomer and easily destroys the pHysical and mechanical properties of the elastomer,while the melamine type polyurethane curing agent is a series of chemical structure modification to melamine,and it has the ability to participate in the crosslinking of the polyurethane prepolymer.A new type of solidifying agent for the structure of the functional group.It is introduced into the elastomer by chemical reaction,which not only does not destroy the pHysical and mechanical properties,but also increases the temperature resistance of the elastomer.(1)The methylation of melamine was prepared by the reaction of melamine and formaldehyde.The mole ratio of the material was adjusted,and the mole ratio of three hydroxylation melamine at normal temperature,then the three hydroxymethylated melamine and benzoyl chloride take chemical reaction,get the product of esterified melamine derivative according to the molar ratio of 1:1,and the regularization structure of the three hydroxylation of melamine was destroyed.A new type of melamine polyurethane curing agent has been synthesized with two-OH structure.(2)Different TDI systems was prepared by reaction of PTMG,polyester 218 and PC polyols with TDI respectively.The polyurethane elastomer was solidification by MOCA and MFBC,and the elastomer was tested by thermal analysis.The results show that MFBC curing agent can effectively postpone the time of peak heat release rate during the combustion of elastomer,TDI+PTMG system deferred 110s,TDI+polyester218 system deferred 180s,TDI+PC type polyol deferred 90s,but the rate of smoke release and total smoke release rate is higher than MOCA.During the process,the mass change rate fluctuates greatly,and the structure of carbon layer after combustion is easy to be destroyed.(3)Polyurethane prepolymer was obtained by using different polyols and MDI reaction respectively.The prepolymer was solidified with MOCA and MFBC respectively,and the MDI polyurethane elastomers of different systems were obtained.The results of thermal analysis show that the MFBC curing agent can delay the peak of heat-release rate and also reduce the peak of heat-release rate.For the MDI+PTMG system,the heat release rate reduces 100Kw·m~2.For the MDI+polyester 218 system,the peak value of the heat release rate decreases by 350 Kw·m~2;but the rate of smoke release and total smoke release rate is higher than MOCA,and the carbon layer after combustion is not uniform.(4)Comparing the TDI and MDI system polyurethane elastomers,the MDI isocyanate index is 33.6%and the TDI isocyanate index is 48.2%,because of the variation of the isocyanate index.The peak value of the MDI type elastomer is180kw·m~2 higher than that of the TDI elastomer,and the MDI system is also more easy to burn than the TDI system.