Seam adhesives, envelope

Seam adhesives are used in manufacturing the side, center, bottom and diagonal seams of the envelopes. Several different types are used including dextrin, resin, and dextrin/resin and starch/resin blends. The specific type used depends on the required adhesion level, application method and machine speed. As the envelope producing machine speed increases, dextrin and dextrin/resin are being replaced by starch/resin blends which are applied by roller, stencil or extrusion. 

The adhesive for the seams on envelope backs must also be at a high solids to prevent strike through, allow fast production speeds, and provide lay-flat. Dextrins or pregelled starches may be used, but are usually heavily plasticized with the lower cost humectant-type plasticizers since blocking is not a factor on... 

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