| 摘要 |
A film that contains a thermoplastic polyurethane and water-soluble polymer is provided. The film is both elastic and water-sensitive (e.g., water-soluble, water -dispersible, etc.) in that it loses its integrity over time in the presence of water. The dual attributes of elasticity and water-sensitivity may be achieved by reducing the tendency of the thermoplastic polyurethane and water-soluble polymer to form separate phases. Namely, phase separation may cause the elastomer to act as a barrier and limit the ability of the water-soluble polymer to contact water and thereby disperse. To minimize such phase separation, a variety of aspects of the film construction may be selectively controlled, such as the nature of the thermoplastic polyurethane and water-soluble polymer, the relative amount of each component, and so forth. For example, thermoplastic polyurethanes are polar in nature and thus may be generally compatible with water-soluble polymers (e.g., polyvinyl alcohol), which are also polar in nature. Further, water-soluble polymers having a relatively low molecular weight and viscosity typically possess better melt compatibility with polar thermoplastic polyurethanes. By carefully controlling the nature of the polymers used to form the film, the present inventors have discovered that a film may be formed that is generally free of distinct phases. |
