杨道胜，侯泽民，许白敏，向文成

(中国石化石油化工科学研究院，北京100083)

聚甲基丙烯酸酯的降凝选择性及其作用机理

杨道胜，侯泽民，许白敏，向文成

(中国石化石油化工科学研究院，北京100083)

文章研究了聚甲基丙烯酸酯(PMA)降凝剂的选择性和降凝机理，在工业上所生产的诸多油品中，从PMA12酯开始到PMA18酯均存在着自己的选择性和降凝范围，而这种性能只与油品的倾点相关。油品的分子量、黏度、蜡分子量和蜡含量只影响降低倾点的幅度(ΔT)大小，而与选择何种PMA并无关系。从PMA12开始出现的脆点反常升高来源于侧链产生的结晶，正是这种侧链结晶使PMA具有了降凝效果，而其降凝范围就是从侧链结晶温度附近开始到从油中析出点结束。这种降凝机理与传统的吸附理论不同，是由于在侧链结晶温度时，PMA在油中也产生侧链结晶而形成梳子状结构，此时油品析出的蜡进入了PMA梳状结构中，产生共晶变成小的蜡晶种，这就防止了蜡进一步形成大片结晶，从而起到降凝的效果。共晶的最好证明就是有侧链结晶的PMA降低了油品的浊点。不同倾点的油品有其最佳降凝效果的PMA醇链，两者之间的线性关系很好。通过不同醇链甲基丙烯酸酯单体的共聚可以为不同倾点的油品量身定做最好的PMA降凝剂，这是因为共聚得到了满足所需要的侧链结晶温度和析出温度的要求，从而达到最佳的降凝效果。

润滑油;聚甲基丙烯酸酯;降凝剂

Abstract:PMA12 to PMA18 has been widely used as pour point depressant in industrial base oil，and each PMA has its own selectivity and effective range based only on the pour point of base oil itself.The selectivity of Polymethacrylate (PMA)pour point depressants and their depression mechanism were investigated.The base oil molecular weight，wax content and wax MW only affect their depression extent not which PMA is most effective.From PMA12 and above the brittle point abnormal increased because of the side chain crystallized occurred.This side chain crystallinity makes those PMA have the ability to depress the pour point of the oil.And their depression range began at this side chain crystallized temperature nearby and ended at the temperature of separated from the oil.The depression mechanism of PMA is different from the traditional absorption mechanism.When the temperature is closed to the PMA side chain crystallized temperature even in the oil solution those PMA begin to form a comb shape side chain crystal.In the meantime when the initial small wax crystal comes out from oil will be captured into this already existing PMA comb and co－crystallized occurred and become a small wax crystal seed.This would prevent it from the wax crystal growing into flake shape large crystals so as to depress the pour point.The good proof of this co－crystallization occurrence are those PMA could decrease the cloud point of the tested oil.Different pour point oil has its favorite side chain length of alcohol in PMA.The oil pour point and the favorite side chain has very good correlation with R2=0.9707.With this equation we could tailor make a best effective PMA depressant for a designated pour point oil by co－polymerization of different methacrylate monomer with different ratio.And this new copolymer has a new side chain crystallized temperature as well as a new separated out temperature，which you are aiming at.

Key words:lubricating oil;PMA;depressant

0 引言

目前在工业界，甲基丙烯酸酯(PMA)作为黏度指数改进剂多用于ATF、液压油和齿轮油，作为降凝剂则广泛用于各种油品包括最大量使用的内燃机油，但关于它的降凝机理和规律发表的文章甚少。……