Two-component solventless urethane laminating adhesives are used in high speed converting of film-to-film laminations for food, industrial goods and lawn and garden packaging. Aliphatic urethane adhesives are typically used instead of aromatic urethane adhesives in applications requiring good uv stability and meeting FDA compliance for cook-in-bag and retort applications. Current commercial aliphatic urethane laminating adhesives either cure too fast or too slow. The faster curing systems typically contain a catalyst giving full cure of the laminated structure in an acceptable timeframe, but has the deficiency of having a short mixed pot-life. The short pot-life causes more frequent shutdowns and clean up of the converting equipment. Low or no catalyst containing systems have slow reaction rates giving favorable long pot-life and requiring fewer shutdowns to clean up. However, the laminated structure containing these adhesives takes several days to up to two weeks to fully cure. To circumvent the slow cure rate, converters use hot-rooms to force cure the adhesive in a reasonable time. This is an added step to their process which requires additional storage space, adds cost, and may be unacceptable for some heat sensitive films. New technology has been developed in solventless aliphatic urethane laminating adhesives to provide long pot-life with faster full cure. This reduces machine down time due to slower viscosity build and also provides fully cured laminates in a shorter time at ambient temperature.
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