Methods for making microporous products
First Claim
1. A method of preparing a relatively homogeneous, isotropic, three-dimensional microporous polymer structure comprising heating a mixture of a synthetic thermoplastic polymer selected from the group consisting of olefinic polymers, condensation polymers, oxidation polymers, and blends thereof, and a compatible liquid to a temperature and for a time sufficient to form a homogeneous solution, allowing said solution to assume a desired shape, cooling said solution in said desired shape at a rate and to a temperature sufficient to initiate thermodynamic, non-equilibrium liquid-liquid phase separation, continuing cooling to form a solid, and removing at least a substantial portion of the liquid from the resulting solid to form the microporous polymer structure.
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Abstract
Novel microporous polymers in forms ranging from films to blocks and intricate shapes from synthetic thermoplastic polymers, such as, olefinic, condensation, and oxidation polymers, are disclosed. In one embodiment the microporous polymers are characterized by a relatively homogeneous, three-dimensional cellular structure having cells connected by pores of smaller dimension. Also disclosed is a process for making microporous polymers from such thermoplastic polymers by heating a mixture of the polymer and a compatible liquid to form a homogeneous solution, cooling said solution under non-equilibrium thermodynamic conditions to initiate liquid-liquid phase separation, and continuing said cooling until the mixture achieves substantial handling strength. Also disclosed are microporous polymer products which contain relatively large amounts of functionally useful liquids and behave as solids.
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37 Claims
- 1. A method of preparing a relatively homogeneous, isotropic, three-dimensional microporous polymer structure comprising heating a mixture of a synthetic thermoplastic polymer selected from the group consisting of olefinic polymers, condensation polymers, oxidation polymers, and blends thereof, and a compatible liquid to a temperature and for a time sufficient to form a homogeneous solution, allowing said solution to assume a desired shape, cooling said solution in said desired shape at a rate and to a temperature sufficient to initiate thermodynamic, non-equilibrium liquid-liquid phase separation, continuing cooling to form a solid, and removing at least a substantial portion of the liquid from the resulting solid to form the microporous polymer structure.
- 16. A method of preparing a relatively homogeneous, isotropic, three-dimensional microporous polymer structure comprising heating a mixture of a polymer selected from the group consisting of olefinic polymers, condensation polymers, oxidation polymers, and blends thereof, and a compatible liquid to a temperature and for a time sufficient to form a homogeneous solution, forming at substantially the same time a plurality of liquid droplets of substantially the same size in a continuous liquid polymer phase by cooling the solution, continuing said cooling to solidify the polymer, and removing at least a substantial portion of the liquid from the resulting solid to form the cellular polymer structure.
- 31. A method of preparing a relatively homogeneous isotropic, three-dimensional microporous cellular polymer structure comprising heating a mixture of a polymer selected from the group consisting of olefinic polymers, condensation polymers, oxidation polymers, and blends thereof, and a compatible liquid to a temperature and for a time sufficient to form a homogeneous solution, forming at substantially the same time a plurality of liquid droplets of substantially the same size in a continuous liquid polymer phase by cooling the solution, continuing cooling to solidify the polymer, at least partially displacing the compatible liquid with a member selected from the group consisting of an intermediate displacing liquid and a functionally useful liquid selected from the group consisting of lubricants, surfactants, slip agents, moth repellents, pesticides, plasticizers, medicinals, fuel additives, polishing agents, stabilizers, insect repellents, fragrances, flame retardants, antioxidants, odor masking agents, antifogging agents and perfumes, with the proviso that when an intermediate displacing liquid is used the intermediate displacing liquid is thereafter at least partially displaced with a functionally useful liquid.
Specification