Research On Formulation Design And Application Of Polyurea Adhesive

Polyurea(PUA)elastomers are formed by the reaction of isocyanate substances with amine-based compositions.Because of its fast reaction gelation,so it is not sensitive to moisture and humidity in the reaction environment.But too fast gel speed will lead to performance degradation and it is difficult to adapt to the hybrid molding process.In the current research work,there are few researches on the formula design principle,performance control method and application of PUA adhesive.In this paper,the flexible control of the gel time and mechanical prop erties of PUA elastomers was achieved by adjusting the formulation parameters.The two-component PUA adhesive formulation is applied to different product fields.(1)In order to reduce the reactivity of amine groups and isocyanate groups.The modified secondary amine crosslinker dipropylcyanodiethylenetriamine(DTAN)was synthesized by the Michael addition reaction between acrylonitrile(AN)and diethylenetriamine(DETA).The gel time of PUA prepared by reacting with isophorone diisocyanate(IPDI)and amine-terminated polyether(JMA-2000,JMA-400)is greatly prolonged;The formulation parameters such as curing parameter R_T,hard segment content H%and crosslinking density C are designed.By adjusting H%and C,the gel time,tensile strength and elongation of the material are respectively 4～200 s,0.84～6.14 MPa,354～1020%range;The experimental study found that the gel point Pc has a significant effect on the gel time of the material.According to the relationship between R _T and Pc,the gel time changes in th e range of 12～38 s by changing the R _T value;On the basis of the four-component formula,the formula of A and B two-component PUA adhesive is designed.The two components react according to different mass ratios and the gel time is controllable within 50 s.(2)Replacing DETA with trifunctional amine-terminated polyether(JMA-403)can improve the compatibility between amine-based components.Three modified crosslinking agents with different activities were obtained through modification.PUA elastomers were prepared by reacting crosslinking agent with isophorone diisocyanate(IPDI)and amine-terminated polyether(JMA-2000,JMA-400)respectively.As the amine activity changed from large to small,the gel time of the material could be extended from 12 s to 85 s,the tensile strength decreased to 3.43MPa,and the elongation increased to 1070%;By changing R _T,H%,C formula parameters,the gelation time,tensile strength and elongation of PUA can be flexibly adjusted in the range of 15～200 s,1.73～9.03 MPa,and 3 25～1630%.The glass transition temperature Tg of the hard segment of the PUA elastomer varies from 17.7℃to 39.6°C;The experiment explores the effect of different modified cross-linking agents on the gel time and mechanical properties of PUA.Using the co mpounded system to design a two-component PUA adhesive formula,the gel time of the material is prolonged and the cured product is in good condition.Low reactive isocyanate-terminated prepolymer PU-400 synthesized by prepolymerization of IPDI and JM-400.The two-component PUA adhesive formula composed of PU-400,JMA-2000,JMA-400,and JMAN-403-3 can further prolong the gel time and solve the problem of poor cured product state caused by excessive viscosity difference between the two components.The gel tim e of PUA elastomer after adjusting the formula parameters of RT,H%and C is more than 10 min.(3)The two-component PUA adhesive formulation with gel time greater than 10min can be applied to seam adhesive materials with static screw mixing extrusion molding device;The two-component PUA adhesive formulation with a gel time of30～60 s can be applied to solid propellant adhesives with continuous feed mixing,continuous extrusion,and rapid gel forming equipment;The two-component PUA adhesive formulation with a gel time of 5～10 s can be applied to explosion-proof coatings with rapid spray reaction molding equipment.