Preparation And Performance Study Of Green Plasticizer Based On Lactic Acid

Polyvinyl chloride(PVC)products are widely used in construction,pipelines,wires and cables,flooring,non-food packaging,windows and many other areas of the national economy worldwide.Phthalate ester compounds that rely on petroleum resources have been the most commonly used additives for PVC materials at home and abroad.However,due to the presence of phthalic acid structures in their molecular structure,they have many toxic effects on the environment and humans.Now domestic and foreign countries have begun to limit the use of phthalate plasticizers in medical products,toys and many sensitive areas in close contact with the human body.At present,with the increasing impact of petroleum-based plasticizers on the environment and the depletion of petroleum resources,people are becoming more aware of the importance of using natural resource-based plasticizer products in PVC production because of biomass raw materials are eco-friendly in nature.The purpose of this study is to use lactic acid as a raw material of corn bio-fermentation as a raw material,through esterification,acetylation and epoxidation reaction design and synthesis of a series ofα-hydroxypropionic acid structure of a new molecular structure of lactate plasticizer.Comparing the application performance of lactic acid plasticizers with traditional commercial plasticizers,the results show that lactate plasticizers have the potential to replace traditional plasticizers.In this paper,L-lactic acid,isooctanoic acid were used as the acid raw materials,1-nonanol,7-methyl-1-octanol,3,5,5-trimethyl-1-hexanol,1,6-hexanediol,ricinoleic acid,cyclohexanol,and triethylene glycol were used as alcohol raw materials,lactate plasticizers(ALSH,ALMH,ALTH,ALHD,ERCAL and ALTGI)were synthesized by esterification,acetylation and epoxidation.The optimal synthesis conditions of the reaction were investigated,and their structures were characterized.It was added as a plasticizer component to the formulation of PVC test strips and performed with several major commercial plasticizers dioctyl phthalate(DOP),dioctyl terephthalate(DOTP),acetylated tributyl citrate(ATBC)application performance comparison.Using 1-nonanol,7-methyl-1-octanol,3,5,5-trimethyl-1-hexanol as the main raw materials,p-toluenesulfonic acid as the catalyst,and cyclohexane as the water carrier,several monoalcohol lactate plasticizers were synthesized by two steps of esterification and acetylation.The preparation route of the reaction was explored,and the best process conditions for the synthesis of lactate plasticizer were obtained:the esterification reaction time was 4 hours,the molar ratio of reactant to alkyd was 1.5:1.0,the catalyst was selected from p-toluenesulfonic acid,the amount of catalyst was 0.8%of the total mass of the reactant.The esterification reaction temperature was 130~oC,the amount of water-carrying agent was 10%of the total mass of the reactant,and the molar ratio of acetic anhydride to the alcohol in the reactant was 1.2:1.0.The molecular structure of the product was analyzed by FT-IR and ~1H-NMR.Several synthetic plasticizers were blended with PVC materials and heat stabilizers to make tablets,and the application effects of the PVC films were analyzed using the solvent immersion method,universal testing machine,and thermogravimetric analyzer.The result showed that a suitable branched chain structure was conducive to improving the thermal stability,extraction resistance and volatility resistance of the PVC films.Having a straight alkyl chain structure in the molecular structure could give PVC more excellent ductility.A new plasticizer with a high ester content,acetylated 1,6-hexanedilactate(ALHD),was synthesized using diol 1,6-hexanediol as the alcohol source,followed by esterification followed by acetylation.The molecular structure of the synthesized product was analyzed by FT-IR,~1H-NMR,MALDI-TOF,and the synthesized product was determined to be the desired product.According to the formula,ALHD gradually replaced the commercially available plasticizer acetyl tributyl citrate(ATBC),and the obtained PVC films were tested for application performance.The result showed that ALHD gave PVC films good extraction resistance and food migration stability.With the increase of ALHD content,the elongation at break of PVC parts increased from 644.65%to 802.15%,an increase of 24.4%.Explored the use of ricinoleic acid,L-lactic acid and cyclohexanol as the main raw materials,through methods of esterification,acetylation,and epoxidation to construct target molecules with vegetable oil and bio-based molecular framework structure,a new type of epoxidized ricinoleic acid cyclohexyl acetylated lactate(ERCAL)plasticizer with relatively large molecular weight was obtained.Its molecular structure and relative molecular weight were analyzed by FT-IR,~1H-NMR,MALDI-TOF.It was used in combination with the environmentally friendly plasticizer dioctyl terephthalate(DOTP).Application performance tests showed that ERCAL plasticized PVC films had excellent thermal stability at high temperatures.With the increase of the amount of ERCAL,the Tg of PVC films decreased from30.8~oC to 19.1~oC,and the elongation at break continued to increase,an increase of 15.4%.Extraction resistance and volatile resistance tests found that after soaking in cyclohexane,petroleum ether,and absolute ethanol for 24 hours,compared with DOTP,the mass loss rates of ERCAL in the three solvents were reduced by 57.1%,48.9%,and 39.7%,respectively.Using triethylene glycol,isooctanoic acid,and L-lactic acid as raw materials,a new type of plasticizer acetylated lactic acid triethylene glycol monoisooctanoate(ALTGI)was synthesized by esterification and acetylation method with an oligomer molecular structure and moderate quality.The molecular structure of plasticizer was characterized by FT-IR,~1H-NMR and MALDI-TOF.Then ALTGI and commercially available plasticizers DOP,ATBC,and DOTP were used to prepare PVC films according to a certain formula.The effects of the amount of plasticizers and types of plasticizers on the application performance of the PVC films were investigated,and the biodegradability of lactate plasticizer ALTGI was investigated by soil burial method and hydrolytic degradation method.The result showed that the plasticizing efficiency of ALTGI in PVC materials was better than the commercially available plasticizers DOP and DOTP when the same amount was added.After 90 days of burial in soil,the degradation rate of ALTGI was about 8 times that of DOP;after 90 days of dipping in phosphate buffer,the degradation rate of ALTGI was about 7 times that of DOP,indicating that ALTGI was in soil and phosphate buffer degradation performance in the significantly better than DOP.