Application Of Modified Phenolic Resin To Acrylic Acid Polymerization Inhibition

Acrylic acid is simple and widely used.The carboxyl group in the structure can react with other groups to produce different acrylate structures and properties.The double bonds in the structure can polymerize them into polymer compounds and generate fast acrylate polymerization speed.It is an important chemical raw material and polymer material monomer in various industries.However,acrylic acid is prone to self-aggregation during its preparation,reaction process,transportation and storage at room temperature and atmospheric pressure,which can easily cause blockage of pipes and waste of raw materials.Therefore,in the above process,a certain amount of polymer inhibitors must be added to inhibit the polymerization.Common inhibitors are hydroxy benzoic ether(MEHQ),hydroquinone(HQ),phenothiazine(PTZ).These inhibitors dissolve in the acrylates,resulting in the costand the time for purification.The purpose of this research is to synthesize insoluble polymerization inhibitors,which can be removed from the system by simple filtration.The thermosetting phenolic resin has the characteristics of stable structure,high temperature resistance and corrosion resistance.The cured thermosetting phenolic resin is insoluble in solvent and does not melt.It will not cause pollution when it is put into the reaction system.Thus,it is very suitable as the matrix of solid insoluble polymer inhibitor.In this paper,the thermosetting phenolic resin was chemically modified with p-hydroxyanisole and hydroquinone,and its structure and polymerization resistance were investigated.The main research contents and conclusions are as follows:(1)Using phenol and formaldehyde as raw materials,NaOH as catalyst,setting the ratio of aldehyde to phenol as 1:1.3,the phenolic resin was modified by using MEHQ and HQ.Thermosetting MEHQ or HQ modified phenolic resins were prepared.The effects of reaction temperature,reaction time,catalyst dosage on the structure,solid content and molecular weight on the modified phenolic resin were investigated.(2)Through the study on the synthesis conditions of modified phenolic resin,the best synthesis conditions were obtained as follows:reaction temperature 85?,reaction time 4h,catalyst dosage 1wt%.The modified phenolic resins with different ratios of phenol to MEHQ or HQ were synthesized under the optimum conditions.After heat curing,the modified phenolic resin was analyzed by infrared and thermogravimetric analysis,and the products had good thermal stability at 130?.(3)The thermal polymerization experiment of acrylic acid was designed.The pure AA system without polymer inhibitor was used as blank group,a certain amount of unmodified phenolic resin was added as control group,and a certain amount of the above solid modified phenolic resin was added as experimental group.Samples were collected and analyzed by gas chromatography.By studying the acrylic acid conversion with time,the polymerization inhibition ability of each solid modified phenolic resin was investigated.The results showed that the polymerization properties of MEHQ-modified phenolic resin and hydroquinone modified phenolic resin were better than those of unmodified phenolic resin.In the phenolic resin modified by MEHQ,the ratio of phenol to MEHQ was 7:3,which showed the best polymerization inhibition effect,and the conversion of acrylic acid was 6.27%after 6 h heating.In the phenolic resin modified by HQ,the ratio of phenol to hydroquinone is 6:4,the polymerization inhibition effect is the best,and the conversion of acrylic acid is 6.18%after heating for 6h.