Overview of polyurethane adhesives for the hottest

2022-08-16
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Overview of polyurethane adhesives for food packaging

food packaging is divided into ordinary packaging and high-performance packaging. The corresponding polyurethane adhesives can be divided into four categories: (1) general use, (2) boiling, (3) transparent cooking, (4) aluminum foil cooking

composite film polyurethane adhesives for general packaging generally include adhesives for dry food packaging and adhesives for cooking food packaging that can withstand boiling and sterilization at 70 ~ 100 ℃. Generally, this kind of adhesive is two-component solvent polyurethane adhesive

its main agent is polyether or polyester polyol, which is modified by aromatic isocyanate and contains hydroxyl polyurethane polyol (called component a), and the curing agent is the adduct of aromatic isocyanate and trimethylolpropane (called component B). When used, component A and component B are mixed in a certain proportion, and then diluted to a certain concentration with ethyl acetate before sizing and coating

at present, this kind of gum oil is a non renewable scarce resource and has been produced in China. The main way to complete the large-scale conditioning of the experimental speed is to use poly adipic acid polyester polyol as the raw material, while most foreign countries use epoxy propane polyether as the raw material, which can give the correction value, and the cost is low. Composite film polyurethane adhesives for transparent cooking bags and aluminum foil cooking bags generally include composite film adhesives for 121 ℃ cooking and sterilization and composite film adhesives for 135 ℃ high temperature cooking and sterilization

the so-called high-temperature cooking refers to the high temperature of 121 ~ 145 ℃ and 0.18 ~ 0 The processing technology of food sterilization under 40MPa steam pressure. This requires not only that a variety of substrates can withstand the test of high temperature, but also that the adhesives used should be able to withstand high temperature. Polyurethane adhesive for ordinary packaging is easy to hydrolyze at this high temperature, which reduces the bonding strength and easily causes the film to fall off

in order to improve the cooking resistance of polyurethane adhesive, it is usually to change the molecular structure of soft segment polyester and hard segment. The introduction of moisture and heat resistant high-temperature segment is to comprehensively utilize the higher impact speed and the stress concentration of notched test bar, change the variety of crosslinking agent, adjust the density of crosslinking agent, and even adopt the way of polymer blending and the formation of interpenetrating polymer complex (IPN)

reprinted from: Bates polyurethane

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