Preparation Of Novel Epoxy Resins With Temerature-controlled Crosslink Network For Fire-resistant Coating

According to the classic polymer foaming theory,the expansion and fire resistance of the intumescent fire retardant coating depends on the melt strength of the matrix resin,which is closely related to the molecular chain structure,crosslink density,molecular chain length of the resin,etc.Resins such as acrylic resin and vinyl acetate,in the molten state,the molecular chain has good mobility,the melt has a suitable melt strength,under the action of gas can foam to form an expanded carbon layer,so a good barrier is obtained Thermal fire resistance.Epoxy resin has excellent weather resistance and bonding strength,but it is a thermosetting resin with a large molecular network structure,high cross-link density,no melting when heated,poor molecular chain mobility,and cannot foam to form an expanded carbon layer at high temperatures,which limits Its application in fire retardant coatings.In this paper,from the perspective of molecular structure,three types of new structural epoxy resins that can form a dissociative adaptive network or combine with an adaptive cross-linking network are designed and prepared.When heated to a certain temperature,the network is partially disconnected or alternated to cool down.At the same time,it bonds again to form a network,which has the characteristics of temperature-controlled cross-linked network.It is used in fire retardant coatings to improve the expansion performance of traditional epoxy resin fire retardant coatings.The specific work is as follows:1.An epoxy resin containing a DA covalent bond was prepared and cured with a curing agent such as dodecenyl succinic anhydride to obtain a new structural epoxy resin with a dissociative adaptive network.Using the Diels-Alder reaction,a DA reverse reaction occurs at about 120℃,destroying the cross-linking network of the epoxy resin.When the temperature returns to 60-90℃,the DA bond recombines,and the macroscopic performance is that the material has a Plasticity.Infrared spectrum analysis,nuclear magnetic hydrogen spectrum and carbon spectrum analysis confirmed the synthesis of DA-containing covalent bond epoxy resin;through differential scanning calorimeter,tensile mechanical properties test,thermal weight loss analysis,etc.,it was found that the use of dodecenyl The decomposition temperature of DA covalent bond in succinic anhydride is 122℃,the tensile strength can reach 11MPa,and it has a good temperature control effect on the crosslinking network of epoxy resin,that is,it can achieve the disconnection of the crosslinking network at a certain temperature.combine with.Using the characteristics of epoxy resin as a temperature-controlled cross-linking network,it is applied to intumescent fireproof coatings.Infrared analysis of fire resistance time,thermal conductivity and carbon layer structure of several epoxy-based intumescent fireproof coatings prepared 3.The thermal stability test of the coating,it is worth mentioning that when using dodecenyl succinic anhydride,the fire resistance time increased from 23min to 41 min,the expansion ratio reached 13,the carbon layer showed extremely low thermal conductivity.2.Using bisphenol A type glycidyl ether,dodecenyl succinic anhydride,ethylene acetone zinc water compounds as raw materials,three anhydride/epoxy network curing systems were obtained according to different ratios to prepare a combination with adaptive crosslinking New epoxy resin for the network.Add zinc ions as a catalyst to the acid anhydride/epoxy crosslinking network.In the presence of mixed carboxylic acid,make the epoxy resin with 3D crosslinking network initiate the exchange reaction of active hydroxy ester above 180℃,at a specific temperature of 180℃ The rearrangement of the epoxy crosslinking network has occurred.The tensile properties,Tg,DMA,creep properties,and thermal weight loss performance tests of the new epoxy resin were carried out.From the results,the tensile strength of the three epoxy resins can reach more than 47MPa.When the Tg is above 40℃,the permanent deformation ratio of the crosslinking network of the third curing system reaches 0.15%at 180℃,and the temperature control effect is the most obvious.Applying the three network systems to the intumescent fire retardant coating,it can be clearly seen that when the third curing system epoxy resin is the matrix resin,the fire resistance time is increased from 23min to 33min,and the expansion ratio reaches 11.3.Using p-aminophenol,hydroxybenzaldehyde,and epichlorohydrin as raw materials,a new type of epoxy monomer containing a dynamic imine bond was prepared.A series of polyetheramine curing agents are used to cure the new epoxy monomer to obtain an epoxy resin with an adaptive network.At 120℃,the exchange reaction between the dynamic imine bond and the free amino group causes the epoxy crosslinking network to rearrange and realize the temperature control of the crosslinking network.Through the infrared spectroscopy,nuclear magnetic resonance hydrogen spectrum and carbon spectrum,tensile properties,thermal weight loss,creep properties and other test analysis of the new epoxy resin,the synthesis of epoxy monomers containing imine bonds was confirmed;and polyetheramine D400 Compared with D2000,when using polyetheramine D230 as a curing agent,the mechanical properties at room temperature reach 50MPa,and the permanent deformation ratio at about 100℃ reaches 0.4%,and the maximum weight loss rate is only 0.56%/℃.And apply new epoxy resin to intumescent fireproof coating.The intumescent fire-retardant coating and the formed carbon layer were characterized by fire resistance,thermal conductivity,scanning electron microscope,infrared analysis,surface element analysis,etc.The results show that when using polyetheramine D230,the fire resistance is improved by 25 minutes,the carbon layer expansion ratio reaches 32.2,the thermal conductivity is only 0.03 W/m/k,and the C/O element content ratio decreases significantly.