Study On The Synthesis And Application Of PVC Auxiliary Heat Stabilizer Pentaerythritol Ester

Polyvinyl chloride?PVC?is one of the most widely used plastic products in the world today.It plays a key role in solving many social needs.Its unique chemical properties will make it very large in the future.Development space.Due to some structural defects in the molecular chain,PVC will degrade and age under O₂,high temperature or light conditions,resulting in poor color and mechanical properties of the product,greatly reducing the industrial value of PVC.Therefore,in actual processing and manufacturing,it is necessary to add a heat stabilizer to improve the thermal stability of PVC.Commonly used heat stabilizers are lead salt,calcium zinc metal soap,organotin heat,rare earth,hydrotalcite and organic additives.Since the lead salt in the lead salt type heat stabilizer is a heavy metal salt.It will cause great harm to the environment and the human body,and will gradually withdraw from the PVC market.Organotin and rare earth heat stabilizers work well,but at a higher cost.Calcium-zinc metal soaps are the most widely used heat stabilizers due to their high efficiency and environmental protection.The disadvantage is that after the addition of calcium-zinc metal soap,the PVC system produces zinc burning,which needs to improve long-term thermal stability.Therefore,the current research focus of calcium zinc metal soap thermal stabilizers is how to improve the phenomenon of avoiding zinc burning and prolonging the initial and long-term thermal stability of PVC systems.Pentaerythrotol?PET?and Dipentaerythritol?DPET?have certain thermal stability effects.Both alcohols are important PVC auxiliary heat stabilizers,but have poor compatibility with PVC.The pentaerythritol ester esterified with carboxylic acid is also an important kind of PVC auxiliary heat stabilizer,which is generally used in combination with calcium zinc stearate.It not only has environmental protection but also has certain plasticizing and lubricating effects,and can meet many PVC processing processes.The requirements of the aspect are thus widely studied and applied.Therefore,PET and adipate are acidified to obtain pentaerythritol adipic acid?abbreviated as APE?,PET and adipic acid,lauric acid esterification to obtain mixed acid pentaerythritol ester?MixPE for short?,DPET and adipic acid,laurate The mixed acid dipentaerythritol ester?MixDPE for short?is obtained.By controlling the degree of esterification,the product retains a part of the hydroxyl group and simultaneously forms a part of the ester group.The pentaerythritol ester thus obtained not only has certain compatibility with PVC,but also has the dual effects of heat stability and lubrication.1.In order to esterify PET and DPET with adipic acid and lauric acid while retaining certain hydroxyl groups,the reaction conditions should be controlled during esterification,and the process conditions for synthesizing pentaerythritol ester should be optimized.The main experimental conditions are catalysts.The type,the amount of the catalyst,the ratio of the alkyd material and the reaction temperature are obtained by mixing PET,DPET,adipic acid and lauric acid in a certain ratio,adding an appropriate amount of the catalyst,heating and stirring to reflux,and then removing impurities and water by vacuum distillation after the reaction.A pentaerythritol ester having good physical properties after optimization of the process conditions is obtained.According to the infrared spectrum analysis of the three esters,the ester carbonyl characteristic absorption peaks were observed in all three products.APE,MixPE and MixDPE showed esters at 1733.5cm^-1,1742.5cm^-11 and 1731.7 cm^-1,respectively.The characteristic peak of carbonyl vibration,3337.2cm^-1,3356.9cm^-1,3289.5cm^-1,is apparently an alcoholic hydroxyl peak,indicating the successful synthesis of pentaerythritol ester.And the DSC curves of APE,MixPE and MixDPE indicate that their melting points are low,and they can be used as auxiliary heat stabilizers in the processing and production of PVC.2.The obtained pentaerythritol ester and stearate were processed according to a certain formula to prepare PVC samples,which were characterized by total reflection infrared spectroscopy.The spectra were compared with the functional groups of PVC samples with pentaerythritol ester added and PVC samples without ester added before and after aging.Changes,the addition of pentaerythritol ester samples before and after aging of PVC molecules did not seriously degrade,the main chain structure was not completely destroyed,indicating that the addition of ester as an auxiliary heat stabilizer PVC samples thermal stability is better than PVC samples without ester added.Subsequently,several ester-added PVC systems were tested for static and dynamic thermal stability.The Congo red test showed the thermal stability of PVC system with a certain amount of ester and calcium stearate heat stabilizer.With a large increase,the thermal stability time of PVC products can be prolonged;the static oven heat aging test shows that the synergy between the three esters and the calcium-zinc heat stabilizer can delay or eliminate the"zinc burning"phenomenon and improve Long-term thermal stability of PVC systems.Thermogravimetric analysis showed that the addition of three esters could increase the initial degradation temperature of PVC system,and the thermal stability was better than that of pure calcium-zinc PVC system.The rheological property test results showed that the torque rheological curve changed with the addition of ester-complexed PVC system.It is gentle,the system is less affected by the outside world,the PVC products are relatively stable,and the dynamic thermal stability is better than that of the pure calcium-zinc heat stabilizer PVC system.Among them,the PVC system with MixDPE as auxiliary heat stabilizer has the best static and dynamic thermal stability.The sample formula is 100 parts PVC,50 parts of dioctyl phthalate,25 parts of heavy CaCO₃,15 parts of light weight.CaCO₃,3 parts titanium white powder,1.5 parts epoxy soybean oil,0.625 parts calcium stearate,0.625 parts zinc stearate and 0.75 parts MixDPE.3.The compatibility of PET and pentaerythritol ester with PVC was investigated by electron microscopy.The experimental results showed that the compatibility of PET and PVC was worse than that of pentaerythritol ester,and obvious PET particle molecules could be observed.It shows that pentaerythritol ester has better compatibility with alcohol in the processing of PVC,and can better increase the long-term thermal stability of PVC.