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High temperature resistant spray adhesive and low temperature polyurethane adhesive
Time：2018-10-31 09:00:25 Page view (1622)
Polyurethane adhesives cured by polyisocyanate crosslinking should not be used under the condition of high temperature cooking above 120 C. In order to prevent the carcinogenic aromatic amines from aromatic polyurethane adhesives from penetrating into the inner layer and endangering health, aliphatic HMDI or IPDI adhesives should be used. In addition, copolymerization can also improve cooking performance. For example, when ethylene carbonate, polyols and TDI were copolymerized and mixed with a suitable amount of curing agent HL (trimethylolpropane: HMDI 1:3 adduct), the measured peeling strength showed that the peeling strength decreased by less than 3% after boiling in water at 120 C for 5 hours. (2) Polyurethane adhesive containing silicone compound was prepared by adding trace amount of (MeO)2SiMe(CH)3NCO and polyester TDI copolymerization. It was mixed with proper amount of curing agent HL and coated on PET film and compounded with nylon. After boiling in boiling water for 3 hours, the peeling strength decreased by only 2%-10%, without the above-mentioned silicone compound. The glue dropped to 35%.
_Solvent-based polyurethane adhesives in China generally have the problem of poor low temperature resistance. Long-term storage in cold areas (below 0 C) will result in crystallization and loss of activity. The higher the viscosity of the polyester with higher crystallinity, the poorer the mobility, and the easier the whitening gel is at low temperature. When polyester is synthesized, natural adhesives with ether bonds and aromatic rings, which react with isocyanate, will not freeze when stored at low temperature. If 80 copies of polybutylene adipate and 20 copies of beta-methyl pentyl lactone mixture containing 20%-10% crystalline polyglycol (melting point 30-70 C) react with diisocyanate, the prepared polymer butanone solution (30%) still maintains good activity after 3 months storage below 0 C, but the activity is worse without adding it. The gum supplied in China is basically aromatic. Although some factories label it as suitable for cooking bags on product specifications, it does not meet the requirements of FDA for food packaging materials. Cooked polyurethane gum is still mostly imported, mainly AD-1010 and AD-1080 of Toyo Ink Chemistry Company of Japan and UK3640 of HENKEL of Germany of EPS-747 of Japan Ink Chemistry Company.
_Solvent-based polyurethane adhesives in China generally have the problem of poor low temperature resistance. Long-term storage in cold areas (below 0 C) will result in crystallization and loss of activity. The higher the viscosity of the polyester with higher crystallinity, the poorer the mobility, and the easier the whitening gel is at low temperature. When polyester is synthesized, natural adhesives with ether bonds and aromatic rings, which react with isocyanate, will not freeze when stored at low temperature. If 80 copies of polybutylene adipate and 20 copies of beta-methyl pentyl lactone mixture containing 20%-10% crystalline polyglycol (melting point 30-70 C) react with diisocyanate, the prepared polymer butanone solution (30%) still maintains good activity after 3 months storage below 0 C, but the activity is worse without adding it. The gum supplied in China is basically aromatic. Although some factories label it as suitable for cooking bags on product specifications, it does not meet the requirements of FDA for food packaging materials. Cooked polyurethane gum is still mostly imported, mainly AD-1010 and AD-1080 of Toyo Ink Chemistry Company of Japan and UK3640 of HENKEL of Germany of EPS-747 of Japan Ink Chemistry Company.
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