Author：Baby & Adult Diaper Materials FROM：Diaper Materials Manufacturer TIME：2023-03-07
Coating, also known as extrusion coating, is to use an extruder to extrude a hot-melt resin to form a film and cover it on the substrate, and then obtain the desired product after cooling.
The substrates used for coating include paper, cardboard, aluminum foil, cellophane, stretched polypropylene, polyester, nylon and high-density polyethylene, among which paper and cardboard are the most commonly used substrates.
The hot-melt resin used for Coated PE film backsheet is polyethylene, polypropylene, propylene-ethylene copolymer, polyolefin plastic, ionomer, thermoplastic polyester, nylon, polycarbonate, etc. Most of the current use is low-density polyethylene, and a small amount is high-density polyethylene.
Coating can produce strong and durable milk packaging boxes, frozen food containers and paper cups, etc. It can not only be used in food packaging, but also in hygiene products, machine parts, pharmaceuticals, cosmetics and other fields.
(1) Coated PE film backsheet materials can be added with certain additives (such as lubricants, stabilizers, antistatic agents, etc.)
(2) The thickness of low-density polyethylene used in Coated PE film backsheet depends on the nature of the substrate, generally not exceeding 50um
(3) Attention should be paid to the cooperation between the coating material and the substrate
For polymers with large molecular weight, they have good crack resistance and good oil resistance. Ionomer resin and polypropylene resin are suitable for oil-resistant composite materials;
Polyolefin plastics with an ethylene content of less than 10% can improve heat-sealing properties and are often used for cold-packed beverages;
Ionomer resins can provide strong, transparent coatings, are easy to bond to aluminum foil, have good oil resistance, can maintain heat sealability in polluted environments, and are used in important hermetic packaging;
Polycarbonate can be used as a high temperature resistant material to produce heatable dishes.
(4) Coated PE film backsheet temperature setting
Coated PE film backsheet needs to understand the relationship between the two thermal effects of external heating and internal frictional heat, the screw speed and the temperature of the material in the screw barrel.
If the screw speed is slow, the output from the die will be less. This shows that the residence time of the plastic in the screw barrel is longer, the plastic is heated in the screw barrel more, and the temperature of the extruded coating material becomes higher;
If the melt index of the coating material is high, the flow rate will be relatively fast. When setting the temperature of the homogenization section, it does not need to be too high.
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