| 摘要 |
Shoe counter stiffeners are cut from material comprising open mesh fabric, a sheet of thermoplastic stiffening composition bonded to each side of the fabric and a coating of thermoactive adhesive on at least one exposed face of the stiffening composition. Suggested mesh fabrics are formed of jute, glass, metal and nylon and are between 0.002 and 0.020 inches thick. The stiffening composition is preferably a polyvinyl chloride homopolymer or copolymer e.g. a copolymer of vinyl chloride and vinyl acetate, or a mixture of polyvinyl chloride polymers and acrylic polymers such as a homopolymer of a methacrylate the alcohol residue of which contains 1 to 4 carbon atoms. Plasticizers of which many examples are given, heat-, light-, and oxygen-stabilizers, colorants, and fillers may be included in the stiffening composition. The thickness of the sheets is between 0.005 and 0.020 inches. The adhesive is preferably a wax with minor amounts of a rubbery composition such as polyisobutylene and a resinous modifier to act as e.g. a plasticizer. The adhesive may be prepared by mixing in a steam jacketed kettle or by solvation in toluence or naphtha and the coating is preferably between 0.0005 and 0.005 inches thick. The sheets of stiffener composition and the fabric may be laminated by subjecting them to pressure at 250 p.s.i. at 350 DEG F. for 5 minutes in a hydraulic press. After 15 minutes' cooling, the laminate is removed and its surface sprayed with the thermoactive adhesive solution. The coated laminate is hung in a circulating air oven, set at 250 DEG F., for five minutes to allow the solvent to evaporate. An alternative method of laminating the sheets to the fabric comprises feeding lengths of sheeting and an interlayer fabric through heated pressure rollers. |
