Nonwoven bag making machines require lubricants for maintenance and repair. How should lubricants for nonwoven bag making machines be selected? If a lubricant only requires internal lubrication, the selection is simple. However, in most cases, it is best to adjust the internal and external lubrication to a certain degree.

The internal and external lubrication functions of a lubricant are determined by its chemical composition, polarity, and solubility in the polymer melt. For example, monoglyceride stearate is soluble in polyvinyl chloride melt and has partial internal lubrication. Its internal lubrication function comes from the two polar hydroxyl groups in the molecule; while glyceryl tristearate only has external lubrication function because it has no hydroxyl groups in its molecule. Of course, the lubrication function is also affected by impurities and other additives in the lubricant.

There are many types of lubricants used for plastics in nonwoven bag making machines, ranging from natural substances such as brown coal wax, paraffin wax, mineral oil, and animal and vegetable oils to various low-molecular-weight polymers such as low-molecular-weight fluoropolymers, silicone oils, and low-density polyethylene. Commonly used are some aliphatic compounds, such as stearic acid, stearic acid soaps, fatty acid esters, and amide compounds.

In 1981, the United States consumed tens of thousands of tons of lubricants in plastic processing, with amides accounting for 45%, stearic acid and its derivatives accounting for 35%, and wax compounds following. Some lubricants, such as oleic acid amide, stearamide, and metal salts of fatty acids (such as cadmium stearate), are also excellent anti-blocking agents. Adding only 0.5% of lubricant to a nonwoven bag making machine can result in excellent smoothness of the film. Of course, fillers such as silicon dioxide and clay are also commonly used anti-blocking agents, with an amount of 0.1-1.0%, and they are often called opening agents.