Study On Structure Optimization Design And Synthesis Of Polyamide Flame Retardant

In recent decades,flame retardants are widely used in all walks of life.so the flame retardant have grown tremendously.various flame retardants were developed and put into use.Among these flame retardants,organophosphorus flame retardants are widely used at present.It has good flame retardant effect and is widely used in various polymer materials.However,its application in polyamide materials is less,and the report of flame retardant polyamides containing P,N or P,S or P,N,S elements is even less.Therefore,several polyamide Flame Retardants Containing P or P,N or P,S or P,N,S were designed and synthesized in order to be applied in polyamide materials The specific research contents are as follows:In the first part,Bis-(p-carboxyphenylamino)methylphosphine oxide(the flame retardant A-Me)was optimized and designed on the basis of Bis-(p-carboxyphenylamino)phenylphosphine oxide(the flame retardant A),and the synthesis method was improved to successfully prepare high purity flame retardant A-Me.After this synthesis method was applied in the industry of the kilogram level of flame retardant A,the high purity flame retardant A was also successfully obtained.The method was improved in the following aspects: 1,4-dioxane as the solvent,dichloromethyl phosphine and ethyl p-aminobenzoate in the ratio of 1:4 to synthesize the flame retardant A-Me ester intermediate.Ethyl p-aminobenzoate is both a reactant and a binder for acids.The flame retardant A-Me with high purity was obtained by alkaline hydrolysis and acidification of ester intermediate products in ethanol-1,4-dioxane-water three-phase system.The total yield is 70% and the purity is above 99%.At the same time,the method has been successfully applied to the synthesis of high purity flame retardant A with A yield of 61% and A purity of 99.5%.This synthetic process has the advantages of high yield,good purity,simple process and suitable for industrial production.The preliminary experimental results show that when the dosage of A-Me is 4%(wt),the limiting oxygen index of polyamide material is greater than 28,and its vertical combustion index is between grade V-0 and grade V-1,which proves that it has A good flame retardant activity.The charcoal-forming flame retardant activity of A-Me was weaker than that of A,indicating that the benzene ring structure in the molecular design of the flame retardant may be beneficial to the improvement of the charcoal-forming flame retardant activity.In the second part,N.N'-bis(6-aminohexyl)-phenylphosphoramide(flame retardant B)was optimized and synthesized on the basis of N.N'-bis(2-aminoethyl)-phenylphosphoramide(flame retardant BPPA),and the two synthesis methods were studied comprehensively and systematically.In method one,Phenylphosphonic Dichloride and hexanediamine were fed at1:2,triethylamine was used as base to react to obtain flame retardant B,but the yield of this method was low.In the second method,flame retardant B is synthesized by a two-step reaction method,that is,hexylenediamine as base,Phenylphosphonic Dichloride and hexylenediamine at a ratio of 1:2 to produce hydrochloride,and then use triethylamine to neutralize,thereby reducing the generation of by-products..After separation and purification,flame retardant B can be obtained.When the amount of flame retardant B is 4%(wt),the limit oxygen index LOI of the obtained flame retardant polyamide is 29.2%,the vertical combustion UL-94 grade is V-0 grade,the flame retardant effect is obviously improved,and it has a good market prospect.In the third part,on the basis of [(6-oxo-(6h)-dibenzo-(c,e)(1,2)-oxphosphine-6-one)methyl]-succinic acid(DDP),the synthesis of 2,3-dicarboxylpropyldiphenylphosphine oxide(flame retardant C)was optimized.According to the preliminary test results of flame retardant C,the synthesis methods of 2,3-dicarboxylpropyldiphenylphosphine sulfide(flame retardant C-S)and 2,3-diaminopropyl-N,N'-bis(2-aminoethyl)diphenylphosphine oxideflame(retardant C-S-N)were further designed,and the synthesis methods were improved and studied.Firstly,the synthesis method of C reported in the literature was improved.Using Chlorodiphenylphosphine as raw material,diphenylphosphine oxygen was prepared on site,and then flame retardant C was prepared by reaction with itaconic acid under the condition of polymer inhibitor,which made the synthesis process more controllable.When 4%(mass fraction)of flame retardant C is added into polyamide,the LOI of flame retardant polyamide is more than 28%.Flame retardant C has been used to flame retardant polyamides.Its reactivity is similar to that of DDP,but its flame retardant activity is obviously weaker than that of DDP.Therefore,this paper further improve the structure of flame retardant C,design and synthesis of flame retardant C-S and C-S-N.In the process of synthesis of flame retardant,Chlorodiphenylphosphine was used as raw material to react with hydrogen sulfide to prepare diphenylphosphorous sulfur,and then the addition reaction with dimethyl itaconic acid ester was carried out to obtain the flame retardant C-S methyl ester intermediate,and then the flame retardant C-S was successfully prepared by hydrolysis.Flame retardant C-S-N was prepared by hydrolyzing C-S methyl ester with ethylenediamine.The thermal decomposition temperatures of C-S and C-S-N are 310? and 330? respectively,which can be used in nylon materials.The flame retardant properties of both of them need to be further tested.