| 摘要 |
A ladder strap ( 150 ) is made by joining-for example, by co-molding-a first, relatively supple material, defining a lower strap portion ( 155 ) with a second, relatively hard material defining an upper strap portion ( 165 ). The teeth ( 167 ) of the ladder strap are comprises substantially of the harder, second material. In a preferred embodiment, the first and second materials are thermoplastic urethanes, and the co-molding is done using an injection molding process. The co-molding process may be accomplished with co-injection, wherein the two materials are injected at about the same time, or the first material may be injected into a first mold cavity and allowed to partially set, after which the cavity is modified to accommodate the second material.
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