Synthesis Of Self-emulsifying Cationic Waterborne Polyurethane Emulsion And Its Application In Fibers

High performance fiber and its resin composites gradually replace steel and other materials with excellent properties such as high strength,good heat resistance,good corrosion resistance,but the fiber itself still has defects,less active functional groups,and poor adhesion to the resin.The properties and applications of the fibers and their composites are limited to a certain extent.In this paper,waterborne polyurethane emulsion was synthesized to improve fiber surface defects,fiber properties and adhesion with resin.There are many kinds of raw materials for the synthesis of polyurethane.The synthesized polyurethane can have a lot of structures and can be designed different molecular structures according to different requirements.They are used as sizing agent for glass fiber/basalt fiber and carbon fiber and provides a high-quality choice.The main design and implementation results of this paper are as follows:1)Synthesis of intermediates:Diethanolamine and octadecyl acrylate are synthesized by the principle of Michael addition reaction.2)Reaction takes place among polyhydroxy polymer?polypropylene glycol,polytetrahydrofuran?,low molecular weight unsaturation unsaturated diol G8,1,4-butanediol and 2,4-toluene diisocyanate,and then the cationic chain extender N-methyl diethanolamine was used for chain extension reaction,and finally polyurethanes are neutralized with glacial acetic acid to form a cationic salt,and emulsified by stirring and feeding distilled water to obtain a cationic aqueous polyurethane emulsion.By changing the ratio of different raw materials and raw materials and the content of intermediates,the molecular structure of cationic waterborne polyurethane is changed,so that the polyurethane has different hydrophilic-lipophilic properties in its molecular chain,its heat resistance is enhanced and particle size of polyurethane emulsion is adjustable etc.With increasing the content of the intermediate,R?NCO/OH?value,and the amount of nano-SiO₂,the particle size of polyurethane emulsion is changing.When polyol is polytetrahydrofuran or isocyanate is isophorone diisocyanate,the synthetic emulsions increase in their particle size,and the particle size of the emulsion can be controlled from 15.20 nm to 530.94 nm.The synthetic emulsion synthesized by using isophorone diisocyanate or polytetrahydrofuran thas better heat resistance than by using 2,4-toluene diisocyanate or polypropylene glycol.The surface tension of the synthetic emulsion is low,indicating that the emulsion has a better wetting effect.When the intermediate content is 33%mole ratio of diols,the surface tension has the lowest value of 33.3 N/m.With my effect of research,it is possible to change the heat resistance,surface tension and the particle size of cationic aqueous polyurethane emulsion by changing the ratio of raw materials or in situ synthetic nanoparticle modification so that the cationic aqueous polyurethane emulsion can formulated as sizing agent to satisfy different products.3)The second types of catonic polyurethanes are synthesized by using polypropylene glycol,1,4-butanediol,low molecular weight diol G8?code?,intermediate content of 23%mole ratio of diols,R=?NCO/OH?=1.5.The sizing agents formulated by the synthetic cationic waterborne polyurethane emulsion CWPU-5 was successfully applied and tested in the production of Zhongfu Shenying carbon fiber and the basalt production line of Jilin Jiuxin Basalt Company,and the all test results meet the production requirements.The carbon fiber and basalt fiber is sized by sizing agent of CWPU-5,the strength of basalt fiber reaches 2.89 Gpa,the modulus is 88 Gpa,the linear density is 206.3 g/Km,and the bulk density is 2.70g/cm³,the maximum tensile strength of carbon fiber is 4.93 Gpa,the tensile modulus is 2.32 Gpa,the elongation at break is 2.7%,and the linear density is 820 g/Km.Their fibers reinforced composites by epoxy resin AG80/vinyl resin have been made,the interlaminar shear strength?ILSS?of the composite from the carbon fiber of the Zhongfu Shenying and the epoxy resin AG80 reached 132.4 MPa.The sizing agent prepared from the cationic waterborne polyurethane film-forming agent in this paper has good wettability with basalt/carbon fiber,the reactive functional groups on the surface of basalt fiber and carbon fiber are increased,the adhesion between fiber and resin is improved,the mechanical properties of the composite are enhanced,and an excellent sizing agent is provided for the production of basalt fiber and carbon fiber.