Blue Spectrum Rick provides a complete set of composite film UV light source. The composite film is mainly composed of two or more layers of different materials, which are mainly used for packaging.
Laminated film is a composite film. The composite film formed by two or more layers must be as inseparable as a film. This involves not only the adhesive between the two films, but also the ink film. Adhesives are synthetic products. Most adhesives are two-component polyurethane (PU) adhesives. Chemical reactions during drilling process solidify the adhesives. The binder on the surface of the base material is mainly a physical process, only a small part of which is a chemical process. At this time, the composition of the binder and the composition of the plastic film drill together and further solidify.
If a film has been printed during the bonding process, then the adhesive and ink should meet more requirements. The most basic requirement is that the inner layer before compounding should have good adhesion fastness and thorough drying. This smells better. Solvent residues are not allowed in the printed lining. However, solvents or alcohols often remain in the ink binder. For this reason, the properties of adhesives must be able to bind to free radicals (- OH group). Otherwise, adhesives and curing agents will bond themselves and lose their cat nature. For example, in the process of compounding, the film has been printed with PVB ink, and there are isoatmospheric salts in the ink. The chemical base of the salt "NCO base" reacts with the free radical OH of alcohol and water. The absence of residue results in inadequate reaction of the adhesives. Then came an inadequate solidification and drilling effort.
In drilling mixtures, solvent-based adhesives are different from solvent-free drilling mixtures such as UV adhesives. Solvent-based drilling mixture needs a drying channel to volatilize the agent. When using UV adhesives, UV light passes through the film to reach the adhesives and aggregate the adhesives together. By compounding, materials with comprehensive properties of each single material can be obtained. The main substrates used are plastic film (such as polyethylene PE, polypropylene PP, polystyrene, polyvinyl chloride PVC and polyester PET), cellophane, paper and metal foil AL. The matrix can be compounded by extrusion or by means of adhesives.
Take polyethylene as an example. The extrusion compounding method is to put polyethylene into hopper, extrude a certain thickness of melt film from the slit through the extruder, and compound and coil the feed base material between the pressure drum and the cooling drum, so as to obtain the product. A three-layer composite film with polyethylene sandwich can be prepared by introducing a second base material from the cooling drum. If polyethylene is added on both sides of the composite film, five-layer composite film can be obtained. This kind of polyethylene composite film is widely used.
Multilayer plastic composite films can also be prepared by co-extrusion. Several different resins were introduced into a common die by several extruders, and then extruded from the die to obtain the product. The device for preparing multi-layer composite films with adhesives is to coat the adhesives on the films or other substrates with a coating machine, dry them in the drying zone, and then hot-press them with other substrates. Substrate coated with adhesives can also be first combined with other substrates, and then dried. Many kinds of composite materials can be compounded by glue.
At present, some inorganic non-metallic thin films have also been prepared using composite thin film preparation technology, which has reached the improvement of photoelectric comprehensive performance.
Through the interaction of different materials in the composite film, the advantages of each layer are accumulated. The following are the functions of the composite film:
1. Steam barrier to prevent wet goods from drying and adding to cool wet towels: to protect dry goods from dampness, such as baked products, powdered products.
2. Acidic barrier. Prevent oxidation, such as for fat and fresh goods.
3. Carbon dioxide barrier. Carbonated beverage is made up of stable packing gas to prevent carbon dioxide loss in MAP packaging.
4. fragrance barrier. Protect the fragrance from volatilization from the package and lose it, such as coffee.
5. odor barrier. Prevent the absorption of external odor or the loss of fragrance.
6. light barrier. Prevent light oxidation such as dairy products.
7, the sealing is firm. Hot pressing is used to seal the composite film.
Main Properties of Composite Films
1. It has good heat-sealing property. Many thin films, such as stretched polypropylene and polyester, have poor heat-sealing property. But when they are compounded with polyethylene with good heat-sealing property, they can greatly improve the heat-sealing property. Therefore, polyethylene thin films are mostly used as inner layer.
2. It has good air tightness, moisture resistance and heat resistance. Cold resistance, aroma retention, anti-ultraviolet penetration and other properties can effectively protect commodities, especially beneficial: for food preservation;
3. It has good commercial performance, good transparency, glossy, good printing, suitable for decoration, plus good rigidity, straightness, shelf effect, attracting customers;
4. It has excellent mechanical properties. It has good tensile strength, impact resistance, tear resistance, piercing resistance, bending resistance, pressure resistance and other properties, plus good adaptability, easy to mechanized operation;
5, lower. On the premise of guaranteeing the comprehensive performance, it can take the method of mixing high and low price materials to manufacture composite films, so the total cost is low.
6. It is light and easy to carry. It can replace some metal cans, glass bottles and other packaging containers. Its weight is greatly reduced. It is also easy to transport, carry and open.