Preparation Of Phenolic/Boron Phenolic Rigid Polyurethane Foam Coating And Its Flame Retardant Performance

Rigid polyurethane foam（RPUF）due to the advantages of low thermal conductivity,excellent thermal insulation performance and convenient construction,is an excellent thermal insulation material for the construction industry to adapt to the era of energy saving,but in the actual application process,RPUF encounters a fire source is very easy to burn and spread very fast,easy to cause serious accident consequences,so the research on RPUF flame retardant performance is very necessary.At present,the commonly used flame-retardant method includes the flame-retardant addition method,which has certain drawbacks and strict process requirements,which is easy to destroy the stable structure of RPUF foam or affect the thermal insulation performance to a certain extent;Reactive and structural flame retardants introduce high-temperature molecular structures into the molecular layer and structure,which is complex and costly.In this paper,the fireproof coating was prepared by surface treatment to be applied to the surface of RPUF to study its flame-retardant properties and mechanical properties,so as to improve the fire resistance and protect the safety of people’s lives and property.In this paper,phenolic resin（PF）and boron phenolic resin（BPF）were used as the coating base.9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide（DOPO）and nano-Si O₂ were used as flame retardant fillers,and fireproof coatings were designed to be applied on the surface of rigid polyurethane respectively to study their flame-retardant properties.The main research contents are as follows:（1）DOPO and nano-Si O₂ with different contents were used as flame retardants to prepare coatings by combining PF,and the effects of coatings added with different contents of flame retardants on the flame-retardant properties of RPUF were studied by vertical combustion test.DOPO and nano-Si O₂ compound and PF were combined to prepare coatings on the surface of RPUF to study the flame-retardant properties and smoke suppression properties of rigid polyurethane foam materials.It is proved that the flame retardant effect of the flame retardant compound is better than that of DOPO and nano Si O₂ alone,when the added content is 8%and 4%,respectively,the peak smoke release rate（SPR）and total smoke volume（TSP）of RPUF after coating are significantly reduced,and nano Si O₂ contains a large amount of hydroxyl groups that will decompose into water vapor during combustion and absorb heat,thereby reducing the heat release rate（HRR）and total heat release rate（THR）values in the cone calorimeter test.The vertical combustion test showed that the RPUF coated with the coating could reach V-0grade,and the residual carbon rate was significantly improved through the thermogravimetric TGA test analysis.（2）BPF/DOPO nano Si O₂ coating is prepared by using BPF as the base,DOPO and nano Si O₂ as flame retardant filler,BPF is the introduction of boron into the molecular structure of PF by self-crosslinking to form a three-dimensional network structure,the resin in the pyrolysis process relative to PF for the release of toxic gases is reduced,thereby reducing the smoke release rate of the coating.The SEM morphology and SEM interface analysis of the two groups of coatings were analyzed.Flame retardant performance research;As well as mechanical property analysis,comprehensive factors show that the flame-retardant performance of BPF/DOPO/nano Si O₂ coating is better than that of PF/DOPO/nano Si O₂ coating.（3）In order to design the BPF/DOPO/nano Si O₂ coating with the best ratio of flame-retardant performance,firstly,single-factor experiments are designed for DOPO,nano Si O₂ and BPF,so that the above three factors as factor horizontal table design orthogonal experiments are obtained by UL-94 vertical combustion test,limiting oxygen index determination,cone calorimeter test and mechanical property test to obtain the best ratio coating to be applied to RPUF in real life.