Preparation And Properties Of Waterborne Polyurethane Containing Ultrafine Fiber Synthetic Leather

Waterborne polyurethane is a kind of polymer material with unique properties.Due to its diversified molecular structure,it can be widely used in adhesives,textile printing and dyeing,leather processing and other fields.In recent years,the application of waterborne polyurethane in ultrafine fiber synthetic leather has developed rapidly.Among them,aliphatic polyurethane materials are widely used due to their excellent yellowing resistance.However,most aliphatic polyurethane materials have low strength and limited water and alkali resistance.Therefore,this article explores the composition of molecular raw materials and reaction conditions of waterborne polyurethane,and finds methods to improve the strength and chemical resistance of waterborne polyurethane.At the same time,it optimizes the process of treating ultrafine fiber synthetic leather and prepares excellent waterborne polyurethane based ultrafine fiber synthetic leather material.Firstly,the effects of monomer isocyanates,polyols,reaction conditions,and the amount of chain extenders on the properties of waterborne polyurethane were studied.The results showed that the waterborne polyurethane lotion obtained by using dicyclohexyl methane diisocyanate(HMDI)and polytetrahydrofuran glycol(PTMEG)as isocyanate and polyol not only had high strength,but also maintained good water and alkali resistance,because its monomer had strong rigidity and chemical resistance.Meanwhile,in the exploration of reaction conditions,it was found that when the R value(-NCO/-OH)was 1.3 and the amount of chain extender 2,2-dihydroxymethylpropionic acid(DMPA)was 15 wt%,the waterborne polyurethane prepared had better performance.The water-based polyurethane material prepared using the above reaction conditions can achieve a tensile strength of 30.2 MPa for the paint film and a water absorption rate of only 2.5%The effects of the concentration of the solution,the concentration of the alkali,the temperature and the time of opening on the properties of the microfiber synthetic leather and the difference of the properties of the microfiber leather caused by the different overlaying methods during the fiber opening process of the aqueous polyurethane material with the best performance of the lotion and the paint film were studied.The results showed that as the concentration of the soaking solution increased,the tear strength of microfiber leather also continued to improve.For comprehensive performance considerations,it was ultimately concluded that when the concentration of the soaking solution was 30%,the tear strength of microfiber leather was higher and the handle was soft.When the concentration of alkali solution is 3% during fiber opening,the tear strength of the microfiber leather obtained reaches 60 N/mm and the handle is soft.The fiber opening rate can reach 40%,and the fiber opening effect is the best at this time.In the exploration of fiber splitting process,maintaining the fiber splitting time at 30 minutes and controlling the fiber splitting temperature at 90 ℃can obtain slightly higher quality microfiber leather materials.In the bonding scheme,1 wt%aziridine is selected as the curing agent,and the wet bonding process is used.When the surface layer thickness is selected as 15 mm and the bonding layer thickness is selected as 30 mm,the peel strength of water-based polyurethane based ultrafine fiber synthetic leather can reach 2.58 N/mm,the bending fastness can reach more than 90000 times,and the wear strength can be around 1100 times.The microfiber leather veneer obtained under these conditions can have the best performance.