1, corona treatment of plastic film surface:
Before the printing and compounding, surface corona treatment must be performed on the substrate PE, PP, and even aluminum foil. The purpose is to improve the printing composite fastness so that it can achieve the desired effect and ensure the critical surface tension during printing and compounding. Greater than 38 millinewtons/meter; for composite films used for cooking, the thickness of the inner substrate should be greater than 70μ to ensure adequate heat seal strength.
2, composite process:
The composite film can improve various characteristics of a single film and can improve the protection of the contents, including moisture resistance, oil resistance, barrier properties, light-shielding properties, and airtightness. According to different substrates and different uses, the composite film processing methods can be roughly divided into the following five categories:
A. Dry-type compounding method This method is a method in which a binder is applied to the surface of a substrate through a laminator, and a heat roller is pressed against the other thin film and compounded. This method can be applied to almost any substrate, how many layers can be compounded, and has been widely used in various fields of packaging materials. Its equipment cost is cheaper than extrusion machine. Recently, retort treatment and boiling sterilization have imposed more stringent requirements on the functional requirements of the packaging. Polyurethanes with excellent adhesiveness are used in many adhesives. In addition, the residual solvents in the dry composite method lead to hazards such as hazards, fires, and explosions. In order to solve such problems, a composite system of different organic solvents should be developed, which has the following advantages:
· No solvent, reduce environmental pollution.
• No risk of fire and explosion.
• No solvent drying process is needed to save energy and equipment footprint.
• There is no solvent for the printing ink.
• No need to recycle solvent plant investment.
• Lower costs due to higher production speeds.
B. Wet compound method This method is mainly used for compounding porous materials such as aluminum foil and paper, sheet paper, and ordinary glass paper. A water-soluble binder (gelatin, starch), a water-dispersible binder (vinyl acetate latex, etc.) is applied to the surface of the base material in a wet state and is compounded with other materials, and then roll-bonded and dried. This method is easy to handle and can be compounded with a small amount of adhesive. The extremely thin aluminum foil (5-6μ) can also be compounded. Compared with other compounding methods, it is fast and can be processed in a large amount. The processing cost is very low. Without organic solvents, the safety is very good, there is no residual solvent, and the market centered on paper-based materials is relatively stable.
C. Extrusion compounding method This is the most commonly used method in compound processing. PP, PE, EVA (ethylene-vinyl acetate copolymer) ion-type resin, etc. are extruded into a film by an extruder, and are pasted into a processing agent. The various films (polyethylenimine, polyurethane resin, etc.) are compounded and cooled and cured. This method saves labor because of the use of an adhesive resin (maleic anhydride-modified olefin-based resin, maleic anhydride and other block-modified olefin resins). Therefore, no adhesive can be used, and the process can be reduced to reduce the cost.
D. Hot-melting compounding method This method mixes rosin and xylene with a base material resin such as EVA (ethylene-vinyl acetate copolymer), EEA (ethylene-ethyl acrylate copolymer), PE, and butyl rubber, which is heated and melted. A hot-melt agent such as a resin, a styrene resin, etc., and a wax-based adhesive base-reducing agent is applied to the surface of the film, the paper surface, and the aluminum foil, and immediately cooled on the other substrates.
It is mainly used to produce cover materials for various containers, and it is required to be resistant to retort. Adhesives are mixed in EVA and other base materials, and extrusion coating is used as a base material to improve heat resistance.
E. Co-extrusion compounding method This method consists of two or three extruders for simultaneous forming and processing to obtain two or more layers of film. There are T-die method and blow molding method, which can carry out a variety of compounding, can produce ultra-thin Shaped film. Japan's annual production reaches nearly 10,000 tons, while over a quarter of US composite membranes are co-extruded membranes. Representative membranes are: PE/PVDC/PE, PE/PP/PE, PP/PE/PVA, PE/EVA, N/PE, etc.
This method has no problem in adhesion of the same kind of resin, but it cannot be bonded to nylon, eval or the like by polyolefin, and a good adhesion can be obtained by using a modified polyolefin having an ionic resin, maleic anhydride Composite film. These co-extruded films have an absolute advantage in the field of food packaging and have a high market share.
Before the printing and compounding, surface corona treatment must be performed on the substrate PE, PP, and even aluminum foil. The purpose is to improve the printing composite fastness so that it can achieve the desired effect and ensure the critical surface tension during printing and compounding. Greater than 38 millinewtons/meter; for composite films used for cooking, the thickness of the inner substrate should be greater than 70μ to ensure adequate heat seal strength.
2, composite process:
The composite film can improve various characteristics of a single film and can improve the protection of the contents, including moisture resistance, oil resistance, barrier properties, light-shielding properties, and airtightness. According to different substrates and different uses, the composite film processing methods can be roughly divided into the following five categories:
A. Dry-type compounding method This method is a method in which a binder is applied to the surface of a substrate through a laminator, and a heat roller is pressed against the other thin film and compounded. This method can be applied to almost any substrate, how many layers can be compounded, and has been widely used in various fields of packaging materials. Its equipment cost is cheaper than extrusion machine. Recently, retort treatment and boiling sterilization have imposed more stringent requirements on the functional requirements of the packaging. Polyurethanes with excellent adhesiveness are used in many adhesives. In addition, the residual solvents in the dry composite method lead to hazards such as hazards, fires, and explosions. In order to solve such problems, a composite system of different organic solvents should be developed, which has the following advantages:
· No solvent, reduce environmental pollution.
• No risk of fire and explosion.
• No solvent drying process is needed to save energy and equipment footprint.
• There is no solvent for the printing ink.
• No need to recycle solvent plant investment.
• Lower costs due to higher production speeds.
B. Wet compound method This method is mainly used for compounding porous materials such as aluminum foil and paper, sheet paper, and ordinary glass paper. A water-soluble binder (gelatin, starch), a water-dispersible binder (vinyl acetate latex, etc.) is applied to the surface of the base material in a wet state and is compounded with other materials, and then roll-bonded and dried. This method is easy to handle and can be compounded with a small amount of adhesive. The extremely thin aluminum foil (5-6μ) can also be compounded. Compared with other compounding methods, it is fast and can be processed in a large amount. The processing cost is very low. Without organic solvents, the safety is very good, there is no residual solvent, and the market centered on paper-based materials is relatively stable.
C. Extrusion compounding method This is the most commonly used method in compound processing. PP, PE, EVA (ethylene-vinyl acetate copolymer) ion-type resin, etc. are extruded into a film by an extruder, and are pasted into a processing agent. The various films (polyethylenimine, polyurethane resin, etc.) are compounded and cooled and cured. This method saves labor because of the use of an adhesive resin (maleic anhydride-modified olefin-based resin, maleic anhydride and other block-modified olefin resins). Therefore, no adhesive can be used, and the process can be reduced to reduce the cost.
D. Hot-melting compounding method This method mixes rosin and xylene with a base material resin such as EVA (ethylene-vinyl acetate copolymer), EEA (ethylene-ethyl acrylate copolymer), PE, and butyl rubber, which is heated and melted. A hot-melt agent such as a resin, a styrene resin, etc., and a wax-based adhesive base-reducing agent is applied to the surface of the film, the paper surface, and the aluminum foil, and immediately cooled on the other substrates.
It is mainly used to produce cover materials for various containers, and it is required to be resistant to retort. Adhesives are mixed in EVA and other base materials, and extrusion coating is used as a base material to improve heat resistance.
E. Co-extrusion compounding method This method consists of two or three extruders for simultaneous forming and processing to obtain two or more layers of film. There are T-die method and blow molding method, which can carry out a variety of compounding, can produce ultra-thin Shaped film. Japan's annual production reaches nearly 10,000 tons, while over a quarter of US composite membranes are co-extruded membranes. Representative membranes are: PE/PVDC/PE, PE/PP/PE, PP/PE/PVA, PE/EVA, N/PE, etc.
This method has no problem in adhesion of the same kind of resin, but it cannot be bonded to nylon, eval or the like by polyolefin, and a good adhesion can be obtained by using a modified polyolefin having an ionic resin, maleic anhydride Composite film. These co-extruded films have an absolute advantage in the field of food packaging and have a high market share.
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