Preparation Of Graphene Oxide Modified Waterborne Polyurethane And Its Application In Packaging Coatings

With the continuous improvement of environmental protection regulations at home and abroad,the packaging and printing industry is seeking better development,and the packaging materials of most products are continuously pursuing safety and environmental protection requirements.Waterborne polyurethane(WPU)is favored in the packaging and printing industry as coatings for its excellent performance.When used for the packaging and printing industry which requires low VOC content,non-toxicity and high temperature resistance,WPU needs to be further modified.As a new type of carbon material with superior properties,graphene oxide(GO)is used in polymers to improve the performance of the materials effectively.In this paper,modified materials are endowed various properties by the combination of graphene oxide and waterborne polyurethane.In this article,polyester diol(PCL),isophorone diisocyanate(IPDI)and methyl methacrylate(MMA)were used as the main raw materials,and both sulfonic acid and carboxylic acid type hydrophilic chain extenders were added.Graphene oxide and modified graphene oxide were used to modify waterborne polyurethane,which prepared zero-VOC,triethylamine-free and high-temperature-resistant waterborne polyurethane-acrylate(WPUA)emulsions and films.Various instruments are used for testing WPUA emulsions and films.The research content of the paper is as follows:(1)Waterborne polyurethane was prepared by using IPDI,PCL and MMA as main raw materials,both 1,4-butanediol and dimethylolbutanoic acid as chain extenders,and then the waterborne polyurethane was blended with GO to prepare a GO/WPUA emulsion without triethylamine.The effect of the amount of GO on the GO/WPUA emulsion was investigated.The results show that a few-layer graphene oxide is prepared,and a low content of GO is dispersed in the WPUA system stably and uniformly.When the GO content is 0.75%,the tensile strength of the films is increased to 30.64 MPa and the heat resistance of the modified composite films is improved to a certain extent.(2)To further enhance the heat resistance of WPUA,GO was intercalated with dodecyltrimethylammonium bromide to obtain the modified graphene oxide product(DTGO).The waterborne polyurethane was modified with DTGO to obtain a GO-modified waterborne polyurethane-acrylate composite emulsion(DTGO/WPUA).The effects of amount of DTGO were studied.The results show that the mechanical properties and heat resistance of the DTGO/WPUA composite films were significantly improved by compounding of GO with waterborne polyurethane.When the amount of DTGO is 0.8%,the tensile strength of the composite film is increased to 48.5 MPa,and the initial decomposition temperature is increased by 21?.At the same time,the addition of DTGO improves the water resistance of waterborne polyurethane films.(3)GO and SiO2 were modified with a silane coupling agent,and modified SiO2 was grafted on the surface of the modified GO.The hybrid filler SiO2-GO was blended into the waterborne polyurethane to obtain a SiO2-GO/WPUA composite material.The effect of SiO2-GO content on the stability of the emulsion was studied.The results show that when the amount of SiO2-GO hybrid filler is 0.7%,the thermal stability and mechanical properties of the modified composite films are improved,and the initial decomposition temperature of the composite film is increased by 24.6?.(4)The application performance of the prepared WPUA samples were tested.The test results showed that adhesion and flexibility of the WPUA on aluminum foil paper had no significant change after modification.However,the product's anti-heat sticking performance has been improved to a certain extent.Neither organic solvents nor triethylamine was added during the synthesis and application of the prepared WPUA,which meets the VOC standard requirements of the packaging and printing industry,and also meets the national standard requirements of packaging products,and the prepared WPUA can be used as packaging materials.