2, the continuous change of the composite: With the increasing hygiene requirements of the society for product packaging, rice vacuum packaging bags are no longer just dry composite, environmentally friendly solvent-free compounding is getting more and more applications. In the solventless compounding, a 100% solid solvent-free adhesive and a composite device are used to bond the film-like substrates to each other, and then the chemical reaction of the adhesive is matured to bond the substrates together. Composite mode. A method of compounding two substrates together on a solventless laminating machine, which is also called reactive type compounding. Since solvent-free composites use solvent-free polyurethane adhesives with two-component and one-component adhesives with a solid content of 100%, solvent-free composites and dry composites have the same physical and mechanical properties. However, it has the advantage of food and environmental protection than dry compounding.