Study On Synthesis And Properties Of Solvent-free Two-component Polyurethane Adhesive

Polyurethane,one of the six major synthetic materials,is developing rapidly.In 2016,the production will reach 18 million tons.As its high adhesive strength,good water and dielectric resistance,polyurethane adhesive gradually become essential to industry and our daily life such as automobile,wood,packaging,shoemaking,etc.Using the isocyanate(MDI)and polyether glycol(PTMEG)as the main raw material,we synthesized the two parts of the solvent-free two-component polyurethane adhesive.We studied the effects of formulation and preparation process on the properties of the products.The curing kinetics and the mechanical properties of the adhesive were also studied by DSC.The main results were:MDI-50 was choosed as the isocyanate monomer because it is inexpensive and convenient to use.Difunctional and trifunctional polyoxypropylene were selected as the polyols.Suitable synthesis conditions were:60-65℃ 5 hours for hydroxy terminated prepolymer(Part A),and 60-65℃ 9 hours for isocyanate terminated prepolymer·(Part B).Under these conditions,we could obtain the product with the tailored NCO content,free MDI content or hydroxyl value.We found that adding proper amount of Antioxidant 168 can prevent the products from turning yellow.We mixed the Part A and B for curing and performance test.Maintaining A and A/B ratio unchanged and changing the difunctional and trifunctional hydroxy proportion in Part B,we studied the curing reaction kinetics of different formulations of polyurethane adhesive properties by DSC.The result showed that,with the increase of the trifunctional proportion of hydroxyl in Part B,apparent activation energy of the curing reaction was first increased and then decreased.The kinetic equation and the reaction order were also obtainedBy rotating viscometer,the viscosity of different formulations of polyurethane adhesive curing in the early curing stage was tested.The suitable A and B component ratio and catalyst dosage were obtained.And the viscosity of the product was suitable for use in production line.The shear strength of Al/Al or stainless steel/stainless steel,peel strength of stainless steel/polyester film were tested.And we found with the increase of the trifunctional proportion of hydroxyl in the Part B,shear strength and peel strength increased firstly and then decreased.When the difunctional and trifunctional hydroxy mole ratio is 2:0.8,the best mechanical properties were obtained.The obtained samples were used on a production line,and the viscosity is suitable for coating at a speed of 350～500m/min.The shear strength and friction coefficient of the products meet the requirements.These results laid the foundation for further research and marketing promotion.