Dry lubricant for conveying containers
The passage of a container along a conveyor is lubricated by applying to the container or conveyor a mixture of a water-miscible silicone material and a water-miscible lubricant. The mixture can be applied in relatively low amounts, to provide thin, substantially non-dripping lubricating films. In contrast to dilute aqueous lubricants, the lubricants of the invention provide drier lubrication of the conveyors and containers, a cleaner conveyor line and reduced lubricant usage, thereby reducing waste, cleanup and disposal problems.
1. A method for lubricating the passage of a container or package along a conveyor comprising:
spray-applying a water-containing lubricant composition comprising from about 0.2 to about 8 wt. % of a water-miscible silicone material and water through a non-energized nozzle to at least a portion of a container-contacting or package-contacting surface of the conveyor or at least a portion of a conveyor-contacting surface of the container or package,
wherein the lubricant composition is not further diluted with water upon application, is applied for a period of time and not applied for a period of time, and the ratio of applied:not applied time is at least 1:10.
2. The method of claim 1 , wherein the silicone material comprises a silicone emulsion.
3. The method of claim 1 , wherein the silicone material comprises a finely divided silicone powder or a silicone surfactant.
4. The method of claim 1 , wherein the lubricant composition comprises at least 50% by weight water.
5. The method of claim 1 , wherein the lubricant composition is spray-applied without high pressure.
6. The method of claim 1 , wherein the lubricant composition is spray-applied without compressed air.
7. The method of claim 1 , wherein the lubricant composition is spray-applied without sonification.
8. The method of claim 1 , wherein the lubricant composition maintains a coefficient of friction of less than about 0.2 on a container-contacting or package-contacting surface of the conveyor between lubricant applications.
9. The method of claim 8 , wherein the lubricant composition maintains a coefficient of friction of less than about 0.15.
10. The method of claim 1 , wherein the container or package comprises polyethylene terephthalate, polyethylene naphthalate, glass or metal.
11. The method of claim 1 , wherein the composition is applied to only those portions of the conveyor that will contact the container or package, or only the portions of the container or package that will contact the conveyor.
12. The method of claim 1 , wherein the lubricant composition is applied for less than one conveyor revolution.
13. The method of claim 1 , wherein the lubricant composition is applied for greater than one conveyor revolution.
14. The method of claim 1 , wherein the ratio of applied:not applied time is at least 1:30.
15. The method of claim 1 , wherein the ratio of applied:not applied time is at least 1:180.
16. The method of claim 1 , wherein the ratio of applied:not applied time is at least 1:500.
17. The method of claim 1 , further comprising determining that the coefficient of friction has reached an unacceptably high level and turning on application of the lubricant composition for a period of time.
18. The method of claim 17 , further comprising turning off application of the lubricant composition when the coefficient of friction returns to an acceptable level.
19. The method of claim 1 , further comprising spray-applying the lubricant composition upstream of a flow of containers or packages.
20. The method of claim 1 , further comprising spray-applying the lubricant composition on an inverted conveyor surface moving underneath and upstream of a flow of containers or packages.
21. The method of claim 1 , wherein the lubricant composition is sufficiently soluble or dispersible in water so that a coating of the lubricant composition on a container or conveyor can be removed from the container or conveyor using conventional aqueous cleaners, without the need for high pressure, mechanical abrasion or the use of aggressive cleaning chemicals.
22. The method of claim 1 , wherein the lubricant composition does not contain emulsifiers or other surfactants that promote environmental stress cracking in plastic containers.