Study On Preparation And Performance Of Transparent Intumescent Amino-Resin Fire-Retardant Coating For Wood

The transparent waterborne intumescent fire-retardant coating has many advantages such as stability of coating,easy to use,low cost and eco-friendly properties.It can protect the wood substrate from fire damage effectively.The transparent coating can retain the original color and grain of wood substrate.In this dissertation,the coating system consisting of melamine urea-formaldehyde?MUF?who performs as the film-forming resin,pentaerythritol?PER?as the carbon forming agent,phosphate as the dehydration catalyst and guanylurea phosphate?GUP?as accretion which has an excellent performance in fire retardancy and smoke suppression was studied.Appropriate formula of the coating system was explored and the effect of GUP on the coating performance was studied.Physical and chemical properties as well as combustion performance of the coating were evaluated.The coating before and after combustion were characterized by fourier transform infrared spectroscopy?FTIR?and scanning electron microscope?SEM?.Specific pyrolysis process of the coating was elaborated.The main results were as follows:?1?Through a large number of orthogonal tests and contrast experiments,the transparent fire-retardant coating with good transparency and excellent performance in fire retardant were screened out,which was made up of MUF resin as film-forming resin and PER-GUP-phosphoric acid as intumescent fire-retardant.When the ratio of GUP to phosphoric acid is lower than c34:d31,the transparency and uniformity of the forming film will be affected,as well as fire retardant performance.When the ratio of GUP and phosphate was higher than c37:d31,GUP will crystallize at the coating surface,reducing the transparency of coating.At the same time,the content ratio of carbon source to acid source is not coordinated.As a result,a soft carbon layer of low density was formed after combustion due to over expanding,with a concomitant decrease in combustion resistance performance.?2?The physical test showed that the coating has a good storage stability.The surface drying time is 1h;hard drying time is 40h;hardness is 3H;adhesion strength grade is 0-1;effective time for use is 27min;the chromatic aberration value between coating and transparent plastic sheet is 0.1016.?3?A comparative study on the combustion performance of self-made coating,commercially available fire-retardant coating,resin coated plywood and plywood panels was carried out by means of cone calorimeter experiment.The results show that the coating has lower heat release rate,total heat release,smoke release rate,CO release rate,CO₂ release rate,and higher residual mass.The coating can protect the substrate from being destroyed in the fire,and has good fire retardancy and smoke suppression performance.?4?The results of SEM showed that the paint-coat of self-made coating is composed of many components.Regular component arrangement is one of the reasons for the transparency of it.The surface structure of carbon layer is uniform;the internal morphology is stable and full of close pores in dense arrangement.?5?Based on infrared spectrum and thermogravimetric analysis,a possible fire-retardant mechanism of self-made coating was proposed.The addition of GUP and phosphoric acid can provide sufficient carbon source for the continuous formation of carbon layer at different temperature ranges,resulting in thorough carbonization of the carbon layer and ensuring the fire-retardant performance of the coating.