The Study Of Modified Nano-SiO₂ With Waterborne Polyurethane UV-curing Crosslink And Its Application

The UV-curing waterborne polyurethane(WPUA) emulsion were synthesized by prepolymer-dispersion-method. Based on this, the nano-Si O2/WPUA composite emulsion were synthesized through the introduction of modified nano-Si O2. Structure and application properties of composite emulsion and cured film were studied, which could provide a theoretical basis for nano-materials modified UV-curing resin preparation and application.By using the basic raw material, such as: 3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate(IPDI), poly-hexanediol adipate diol(PHA), dimethylol propionic acid(DMPA), pentaerythritol triacrylate(PETA), this study prepared UV-curing waterborne polyurethane emulsion through prepolymer-dispersion-method. The Structural characterization of WPUA films was studied by means of Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), X-ray diffraction(XRD), thermal gravimetric analysis(TGA);the micro-phase separate of WPUA was decreased obviously compared with WPU, and WPUA film section reticular structure, The crystallized peak of WPU and WPUA were mainly conversed into amorphous dispersion broad peak, but the crystallized peak of WPUA decreased obviously; the thermal stability of UV-curing waterborne polyurethane was higher than waterborne polyurethane. It systematically studied the effects of the amount of DMPA, R values, double bond content, the amount of photoinitiator, drying temperature, curing time on the properties of WPUA emulsion and film properties. The results showed that when DMPA mass fraction at 3.5%, R values was 2.3, the double bond content of 0.81mmol/g-1.28mmol/g, photoinitiator mass fraction at 3%, drying temperature was 80℃, the illumination time was 15 s, the WPUA emulsion showed a stable performance, and the WPUA film has good properties.On the basis of the above, then using 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate(IPDI) and hydroxyethyl acrylate(HEA) modified nano-Si O2, in order to improve its dispersion in an organic polymer, and make nano-Si O2 have polymerize performance. FT-IR showed that the double bonds which can be light curing reaction were introduction on nano-Si O2 surface; SEM observation showed that: modified nano-Si O2 agglomeration significantly improved. Under ultrasonic conditions, modified nano-Si O2 and WPUA were blended, then using UV irradiation nano-Si O2 which have a double bond were grafted on UV-curing waterborne polyurethane(WPUA), finally obtain a modified nano-Si O2/WPUA film. The Structural characterization of modified nano-Si O2/WPUA films was studied by means of FT-IR、AFM、 SEM、 XRD. The results showed that the phase separation of the UV-curing composite film decreased; the intensity of the diffraction peaks film crystallization significantly decreased and no impact of UV-curing waterborne polyurethane flatness when modified nano-Si O2 were added in; There has significantly different film fracture surface between the nano-Si O2 added in or not, which indicates that add modified nano-Si O2 change the microstructure and crystallization ability of the film. The properties of film were tested by thermal properties, DSC. The results revealed that: the heat resistance of WPUA film significantly improved, When modified nano-Si O2 were added, when the mass fraction of modified nano-Si O2 was 5%, compared with WPUA the hard segments improved 23℃, the soft segment improved 11.5℃, compared with WPU the hard segment improved compared to 38℃, the soft segment improved 30.5℃, hard and soft segments phase separation in the polymer is not obvious, and only one glass transition temperature. It studied the effects of the amount of modified nano-Si O2 on the properties of WPUA emulsion and film properties. Emulsion particle size analysis showed that: at low nano-Si O2 content, the amount of inorganic particles in the emulsion is more uniform, narrow particle size distribution, with the increase of nano-Si O2 content, particle size distribution wider obviously. when the mass fraction of modified nano-Si O2 was 5%, water absorption was 2.418%, the tensile strength and elongation at break of the film were up to the maximum of 10.303 Mpa, 368.807%, compared with the film which no added modified nano-Si O2 increased 40.49% and 66.30%, respectively, composite material has the best water resistance and mechanical propertie.Application results show that the modified UV curing nano-Si O2 /WPUA microfiber synthetic leather has good health performance, hydrolysis resistance and abrasion resistance.