高聚物的在熔融之后通常具有较高的粘度，在加工过程中，熔融的高聚物在通过窄缝、浇口等流道时，聚合物熔体必定要与加工机械表面产生摩擦，有些摩擦在对聚合物的加工是很不利的，这些摩擦使熔体流动性降低，同时严重的摩擦会使薄膜表面变得粗糙，缺乏光泽或出现流纹。为此，需要加入以提高润滑性、减少摩擦、降低界面粘附性能为目的助剂。这就是润滑剂。润滑剂除了改进流动性外，还可以起熔融促进剂、防粘连和防静电剂、爽滑剂等作用。 润滑剂可分为外润滑剂和内润滑剂两种,外润滑剂的作用主要是改善聚合物熔体与加工设备的热金属表面的摩擦。它与聚合物相容性较差，容易从熔体内往外迁移，所以能在塑料熔体与金属的交界面形成润滑的薄层。内润滑剂与聚合物有良好的相容性，它在聚合物内部起到降低聚合物分子间内聚力的作用，从而改善塑料熔体的内摩擦生热和熔体的流动性。常用的外润滑剂是硬脂酸及其盐类；内润滑剂是低分子量的聚合物。有的润滑剂还有其他的功用。实际每一种润滑剂都有可以实现某一要求的作用，总是内外润滑共同作用，只是在某一方面更突出一些。同一种润滑剂在不同的聚合物中或不同的加工条件下会表现出不同的润滑作用，如高温、高压下，内润滑剂会被挤压出来而成为外润滑剂。 在塑料薄膜的生产中，我们还会遇到一些粘连现象，比如在塑料薄膜生产中，两层膜不易分开，这给自动高速包装带来困难。为了克服它，可向树脂中加入少量增加表面润滑性的助剂，以增加外部润滑性，一般称作抗粘连剂或爽滑剂。一般润滑剂的分子结构中，都会有长链的非极性基和极性基两部分，它们在不同的聚合物中的相容性是不一样的，从而显示不同的内外润滑的作用。

The high polymer usually has a high viscosity after melting. During the process, the polymer melt must have friction with the machined surface when the molten polymer passes through the narrow slit, gate and other flow channels. Some friction is disadvantageous to the processing of the polymer. These frictions reduce the melt fluidity and are strict at the same time. Heavy friction will make the surface of the film rough, lacking luster or rhyming. Therefore, additives should be added to improve lubricity, reduce friction and reduce interfacial adhesion. This is the lubricant. Besides improving fluidity, lubricants can also act as accelerators, anti adhesion and antistatic agents, and lubricants. Lubricants can be divided into two types: external lubricants and internal lubricants. The role of external lubricants is mainly to improve the friction between polymer melts and hot metal surfaces of processing equipment. It has poor compatibility with polymers and is easy to migrate from the melt, so it can form a thin lubricating layer at the interface between plastic melt and metal. The internal lubricant has a good compatibility with the polymer. It plays a role in reducing the cohesion of the polymer molecules within the polymer, thus improving the internal friction heat and the fluidity of the melt. Commonly used external lubricants are stearic acid and its salts, and internal lubricants are low molecular weight polymers. Some lubricants have other functions. In fact, each lubricant has the function of achieving certain requirements, which is always combined with internal and external lubrication, but it is more prominent in one aspect. The same lubricant can show different lubricants in different polymers and different processing conditions, such as high temperature and high pressure, and the internal lubricants will be squeezed out and become external lubricants. In the production of plastic film, we will also encounter some adhesion phenomena, for example, in the production of plastic film, two layers of membrane are not easy to separate, which brings difficulties to automatic high-speed packaging. In order to overcome it, a small amount of additives to increase surface lubricity can be added to the resin to increase external lubricity, commonly referred to as anti adhesion or lubricant. In the molecular structure of the general lubricants, there are two parts of the long chain, the non polar and the polar groups, and their compatibility in different polymers is different, which shows the effect of different internal and external lubrication.