| 摘要 |
<p>Heat sealing of wrapper laminates (31, 32) made of foam (102) supported by a porous substrate sheet is improved by coating on the foam-engaging face of the substrate a barrier layer such as polyvinylalcohol to keep the foam (102) when melted from bleeding through the substrate. The support for the foam can alternatively be non-porous film such as polyethylene terephthalate. In a cold sealing embodiment the foam face of supported foam wrappers has a cohesive-nonadhesive layer which can contain improved volatile corrosion inhibitor and/or antistat compositions that do not shorten its shelf life below about six months. One such composition is a mixture of dicyclohexylamine with 2-amino-2-lower-alkyl-propadiol-1,3. Protective colloid such as polyvinylpyrrolidone is preferably also added to improve the compatability of the volatile corrosion inhibiting composition with the rubber latex that provides the cohesive-nonadhesive characteristics. Heat sealing of wrapper can be effected with the help of hot melting shoes (39 and 41).</p> |
