Preparation And Properties Of Silicone Modified Waterborne Polyurethane

Waterborne polyurethane,a green environmental protection material,can be widely used in adhesives,coatings,inks,biomedicine and other fields.Compared with conventional polyurethane,waterborne polyurethane often shows lower water resistance and mechanical properties,which limits its application to a certain extent.Based on this,three kinds of silicon modified waterborne polyurethane were designed by means of chain extender molecular design and nano hybrid composite to improve their water resistance,thermal stability and mechanical properties.The main research contents and results are as follows:(1)4,4'-(1,1,3,3-tetramethyldisiloxane-1,3-dipropyl)bis-2-methoxyphenol(EUSi)was synthesized from eugenol and 1,1,3,3-tetramethyldisiloxane,and used as chain extender with DMPA to prepare waterborne polyurethane emulsion.The effect of EUSi addition on the properties of waterborne polyurethane was investigated.With the increase of EUSi content,the particle size became larger and the particle size distribution of the emulsion also broadened.When the EUSi content was 3%,the maximum tensile strength of the material increased from 6.2 MPa to 22.4 MPa,the water contact angle increased from 77.6° to 103° and the water absorption decreased from 31.3%to 7.6%.(2)3-isocyanate propyl trimethoxy silane(IPTMS)was grafted onto the surface of cellulose nanocrystalline(CNC)to prepare silicone modified cellulose nanocrystals(ICNC)(T5%CNC at 172.1 ?,T5%ICNC at 297.3?),and then ICNC/WPU emulsions were prepared through in-situ polymerization.When the content of ICNC was 2%,the T5%of the sample increased to 257.3?,the maximum tensile strength and modulus were 21.3 MPa and 21.2 MPa,and the elongation at break was 723.2%,respectively.The water absorption of the sample after 24 hour is 11.6%.(3)Tetrahydroxyoctaphenyl double cage polyhedral silsesquioxane(DDSQ)was synthesized from phenyltrimethoxysilane and was introduced into waterborne polyurethane system by in-situ polymerization and blending.The influence of the introduction way and content of DDSQ on the thermal stability,mechanical properties and water resistance of nanocomposite emulsion was explored.The results showed that the samples prepared by blending had better thermal stability in air atmosphere,while the composites prepared by in-situ polymerization had better mechanical properties and water resistance.(4)The application of silicone modified waterborne polyurethane composite in water-based ink was also studied.The results showed that the performance of the self-made ink could meet the general requirements,and the ink prepared by ICNC/WPU had faster drying speed and stronger adhesion fastness to PET substrate.