Eartip
An improved EarTip may result from the distribution of PTFE throughout a slow recovery foam. Such an EarTip may have a finer, more uniform cell structure that aids in insertion within a user's ear canal. It may also have a smoother skin, with a lower kinetic coefficient of friction, and may provide improved sound attenuation.
1. An EarTip comprising:
a main body portion constructed to enable its reception in an ear canal,
the main body portion being formed of pressure-molded slow recovery low resilient foam plastic material that comprises:
slow recovery low resilient polyurethane foam with cell structures that have a low coefficient of friction additive distributed throughout each of the cell structures, and
multiple gas-filled open cells defined by the cell structures,
wherein a plurality of the cell structures form a skin on an exterior of the EarTip, and
wherein the low coefficient of friction additive distributed throughout each of the cell structures comprises PTFE.
2. The EarTip of claim 1 wherein the foam is formed by:
providing a prepolymer stream and a latex aqueous solution stream;
adding between 2 to 7% by weight PTFE to the latex aqueous solution stream; and
mixing, in a closed mold under at least 0.5 pounds per square inch of pressure, the prepolymer stream and the latex aqueous solution stream, wherein the latex aqueous solution stream comprises at least 60% solids.
3. The EarTip of claim 1 , wherein the main body portion comprises a hollow foam shell, and wherein the hollow foam shell of the main body is configured to directly contact the ear canal without any intervening material between the ear canal and the foam.
4. The EarTip of claim 1 wherein the slow recovery low resilient polyurethane foam is latex-modified polyurethane foam.
5. The EarTip of claim 1 wherein the additive is approximately uniformly distributed throughout the cell structures of the foam plastic material.
6. The EarTip of claim 1 wherein the main body portion forms an earplug.
7. The Ear Tip of claim 1 wherein the main body portion comprises an aperture therethrough, the aperture being operable to receive a sound tube.
8. An EarTip comprising:
a main body portion constructed to enable its reception in an ear canal,
the main body being formed of pressure-molded slow recovery low resilient foam plastic material comprising:
slow recovery low resilient polyurethane foam with cell structures that have a low coefficient of friction additive distributed throughout the cell structure, and
multiple gas-filled open cells defined by the cell structures,
wherein the main body portion has a static coefficient of friction greater than 1.70 and a kinetic coefficient of friction less than 1.47.
9. An EarTip comprising a main body portion constructed to enable its reception in an ear canal, wherein:
the main body is formed of slow recovery low resilient foam plastic material comprising multiple open cells defined by cell structures that have low coefficient of friction additive distributed throughout the cell structures;
the average diameter of the cells is smaller than that of standard slow recovery low resilient foam plastic without additive, wherein the additive comprises PTFE; and
the main body has a cross-section, wherein the average diameter of the cells does not vary across the cross-section as much as that of standard slow recovery low resilient foam plastic without additive.
10. The EarTip of claim 9 , wherein the foam is formed by:
providing a prepolymer stream and a latex aqueous solution stream;
adding between 2 to 7% by weight PTFE to the latex aqueous solution stream; and
mixing the prepolymer stream and the latex aqueous solution stream, wherein the latex aqueous solution stream comprises at least 60% solids and materials in the prepolymer stream and the latex aqueous solution stream foam under pressure in a closed mold.