Preparation Of Fluorine-containing Functional Coatings

As a kind of novel functional coating,electrothermal coating has been widely applied in heating,airport deicing and outdoor display fields.Adhensives play a significant role in the preparation of electrothermal coatings and have a decisive impact on the basic performance of coatings.Currently many adhensives have been developed and used in research and industry,such as epoxy resin,polyurethane,polyacrylic resin and so on.However,these adhesives have bad heat stability and weather resistance,which limits its development and application in daily life.Besides,according to literatures,the preparation of electrothermal coatings usually use organic solvent,which could release volatile organic compound(VOC)during the curing process and will affect health and environment.However,the strong C-F bond and large steric hindrance provide the fluororesin with stable structure,improved its excellent weatherability,corrosion resistance and heat-and-cold resistance.In this work,graphite/fluorine emulsion and graphene/fluorine resin composites were prepared and the properties of the electrothermal coatings were thoroughly studied.The detail research contents are as follows:The first part:at first,the fluorinated water-based electrothermal coating was facilely prepared by uniformly dispersed graphite in fluorine emulsion with additives.Then the electrothermal coating was deposited on glass substrate to form electrothermal films.Finally,the microstructure and particle distribution of electrothermal film was characterized by Scanning Electron Microscope(SEM).The electrothermal properties were tested via Cen-Tech digital multimeter and electrical parameter tester.The experimental results revealed that the electrothermal films(2.5 cm×7.5 cm,thickness of~60?m)exhibited low volume resistivity of 0.15?·cm with uniform temperature distribution,and the heating power maintained 12.24 W when the content of graphite flakes was 30 wt%.The surface steady-state temperature of films increased from 26.2 to 303.4 ~oC and the contact angle of electrothermal films increased from 47.1~o to 93~o with increasing the content of graphite flakes in a range between 15 wt%and 30 wt%at the thickness around 60?m(~20 V,18±2 ~oC).A continuous conductive network was formed with increasing the content of graphite in coating,which was shown in SEM.In deicing experiment,the ice(0.25 g)on the coatings with 30wt%graphite was soon melted in 135 s at the low voltage~20 V,while the ice on electrothermal films kept the same due to no voltage inputting.The results above demonstrated that graphite/fluorine emulsion electrothermal coatings had excellent deicing performance.The second part:the graphene/fluorine resin composites was facilely prepared by uniformly dispersed graphene dispersion in fluorine resin by ultrasonic blending with tetrafluoro-resin as adhesive and grapheme as conductive filler.The composites were then deposited on the polyethylene terephthalate(PET)and glass respectively to form electrothermal films.SEM was used to characterize the microstructure and particle distribution in electrothermal film.The electrothermal properties were detected by two probes of a Cen-Tech digital multimeter and electrical parameter tester.The results indicated that the graphene electrothermal films had low volume resistivity of 0.17?·cm when the content of graphene is 2.0 wt%in the coating(2.5 cm×7.5 cm and the coating thickness of about 60?m),at room temperature.In addition,the tetrafluoro-resin insulating coating gradually became conductive.When the body safe voltage of 10 V,15 V,20 V,25 Vand 30V respectively were applied for the graphene/fluorine resin coatings containing 1.8 wt%and2.0 wt%graphene,the surface steady-state temperature of electrothermal films with the content of graphene of 1.8 wt%increased from 15.0 to 40.9 ~oC and its heating power maintained 12.24 W.However,as for the electrothermal films with 2.0 wt%graphene,the surface steady-state temperature increased from 29.5 to 142.8 ~o C and the heating power reached to 12.65 W.At last,the tensile strength of graphene/fluorine resin composites coating can reach to 48.27 MPa when the content of graphene was only 0.1 wt.%,while the tensile strength of the coatings decreased with further increasing graphene content.Moreover,after bending 100 times,the graphene/fluorine resin coating still exhibited almost the same electrothermal performance,which has shown its excellent flexibility.The experimental results showed that the graphene/fluorine resin composite coatings have potential applications in electrothermal deicing,heating and so on.