Novel silica gel gasket

Abstract

A silica gel prosthetic pad for use with a prosthetic assembly, the silica gel prosthetic pad acting as an interface between an amputee stump and a socket assembly. The prosthetic pad includes an open proximal end, a closed distal end, and a sidewall containing an inner layer of molded silica gel. The silica gel is molded on a mandrel that has been blasted at 100 psi using # 36 sand grains and optionally # 320 sand grains to form micro-pits and reduce the coefficient of static friction.

Description

[0001] Citations of Related Applications

[0002] This application claims priority to pending application serial number 17 / 742,721 filed on May 12, 2022, which is a continuation-in-part of application serial number 16,868,776 filed on May 7, 2020, entitled "New Silicone Liner", which claims the benefit of provisional application number 62 / 844,253 filed on May 7, 2019 and provisional application number 62 / 844,296 filed on May 7, 2019, the disclosures of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to liners for use in prosthetic components. In particular, the invention relates to liners having a silicone lining that is made smooth to the touch by sandblasting a mold used to create the liner. Background Art

[0004] Silicone pads have been used in the prosthetic industry since the 1980s, such as those described in U.S. Pat. No. 4,923,474 to Klassen and Kristinsson. Other examples of such pads include U.S. Pat. No. 5,728,168 to Laghi et al., U.S. Pat. No. 5,830,237 to Kania, U.S. Pat. No. 5,507,834 to Laghi et al., U.S. Pat. No. 5,443,525 to Laghi et al., and U.S. Pat. No. 5,728,168 to Laghi et al.

[0005] However, silicone liners have historically been difficult to put on and take off due to the high static friction coefficient of silicone. As a result, they tend to stick to the skin of the residual limb. This prevents relative movement at the interface skin / liner, so high shear forces are generated on the local skin of the residual limb when the reaction forces of the face to walking are transmitted to the bone through the silicone interface and skin. These generated shear forces increase the possibility of skin blistering, especially for patients with sensitive skin. Therefore, it is desirable to develop a silicone liner with a friction-reducing effect so that users can easily put on and take off their prosthetic liner.

[0006] Further, most amputees have their limbs amputated for vascular reasons rather than traumatic reasons. This means that the amputation is due to poor circulation. Most amputees are also elderly. Therefore, most amputees have thinner, more fragile skin that is easily damaged, and reduced blood flow to their limbs, making them less able to heal sores and wounds. Some elderly amputees end up having repeated amputations due to damage and infection of the skin on their stumps.

[0007] One approach developed to thwart these problems is to include an additive that oozes out of the silicone matrix and acts as a lubricant between the pad and the skin. The problem with this solution is that the exudate can collect dirt on the inner surface of the pad, exacerbating skin damage. The exudate also requires more thorough cleaning and lubrication of the pad.

[0008] The present invention uses a new sandblasting technique to create "microcraters" in the silicone of a prosthetic liner when molded, making the liner easy to put on and take off, and skin-friendly. The method described herein is particularly effective for silicone liners because silicones have a lower surface tension when liquid, allowing them to penetrate into tiny pores and cracks, thus creating microcraters. The viscosity of silicone is also inversely proportional to temperature, allowing silicone to flow more easily when close to the surface of the hold mold. As a result, the silicone creates a faithful (faithful, accurate) mirror image of the cratered mold surface.

[0009] It is therefore an object of the present invention to provide improvements which overcome the above-mentioned deficiencies of prior art devices and which contribute significantly to the advancement of gasket technology.

[0010] Another object of the present invention is to provide a silicone pad having an inner silicone lining that is more comfortable.

[0011] Another object of the present invention is to provide a method of making a silicone gasket having friction reducing properties.

[0012] It is another object of the present invention to provide a liner having dimples.

[0013] Another object of the present invention is to describe a method of manufacturing a silicone gasket by molding the gasket using a sandblasted mold mandrel.

[0014] The foregoing has outlined some of the relevant objects of the present invention. These objects should be understood as merely illustrating some of the more prominent features and applications of the contemplated invention. By applying the disclosed invention in different ways or modifying the invention within the scope of the disclosure, a number of other beneficial results may be obtained. Therefore, in addition to the scope of the invention defined by the claims in conjunction with the accompanying drawings, other objects of the present invention and a more comprehensive understanding of the present invention may be obtained by reference to the summary of the invention and the detailed description of the preferred embodiments. Summary of the invention

[0015] The present invention generally relates to a liner for use in a prosthetic assembly having a silicone interior containing micro-dimples formed by sandblasting a silicone mandrel using #36 grit at 100 psi. Using the sandblasted mold mandrel, a silicone liner having improved frictional properties can be manufactured. The liner of the present invention may optionally include a fabric cover bonded to the outer surface.

[0016] The foregoing fairly broadly summarizes the more relevant and important features of the present invention so that the following detailed description of the present invention can be better understood, thereby more fully understanding the contribution of the present invention to the art. Other features of the present invention will be described below, and these features form the subject matter of the claims of the present invention. It should be understood by those skilled in the art that the disclosed concepts and specific embodiments can be easily used as the basis for modifying or designing other structures for achieving the same purpose of the present invention. It should also be appreciated by those skilled in the art that such equivalent structures do not deviate from the spirit and scope of the present invention as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a front view of the improved silicone pad.

[0019] Figure 2 is a cross-sectional view of a silicone sheet formed using a core mold that has not been sandblasted.

[0020] Figure 3 is a cross-sectional view of a silicone sheet formed using a mandrel that was sandblasted with #36 grit at 100 psi.

[0021] Figure 4 is a cross-sectional view of a silicone sheet formed using a mandrel that was sandblasted with #320 grit at 100 psi.

[0022] Figure 5 is a graph showing the effect of sandblasting on the pull force required to remove a silicone sheet from a steel substrate, showing the effect on the static coefficient of friction.

[0023] Like reference numerals refer to like parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0024] The following description is the best mode of implementing the present invention currently contemplated. This description should not be construed as limiting, but is only used for the purpose of describing one or more preferred embodiments of the present invention. The scope of the present invention should be determined with reference to the claims.

[0025] The present invention relates to a liner 100 for use with a prosthetic device. Figure 1 As shown, a liner 100 for use with a prosthetic assembly includes an open upper end 12 for receiving a residual limb (not shown), a closed bottom end 14, and a side wall 16 of a predetermined thickness. The liner is airtight when worn on the residual limb. The preferred thickness of the side wall 16 is about 1.5 mm to 3.0 mm. Note that the thickness of the bottom end is greater than the thickness of the side wall; the preferred thickness of the silicone at the bottom end 14 is about 3.0 mm to 12.0 mm. The side wall 16 has an inner layer 18 of the improved silicone described herein. The side wall 16 can be fabric or another layer of more durable and higher friction silicone.

[0026] Prior to molding the silicone, the core mold was sandblasted using #36 grit at 100 psi. The specific grit and pressure used provide the beneficial properties of the present invention. Other grits and pressures do not produce the benefits of reduced frictional hold and reduced potential for skin irritation. After sandblasting the core mold, silicone was molded over it, allowing the silicone to penetrate into the micro-pits formed by sandblasting. Figure 2-4 As can be seen, the size of the grit used in the blasting process has a considerable effect.

[0027] Figure 2 A silicone sheet 20 that has not been sandblasted is depicted. As can be seen from cross section 2-2, not sandblasting the core mold results in a smooth outer surface 22, which maintains the high friction properties of the silicone. On the other hand, Figure 3 and Figure 4 A microscopic view of the outer surface 22 of the core mold after sandblasting is shown. Figure 3 The outer surface 22 is shown micro-dimpled using #36 grit at 100 psi, thereby forming micro-dimples 24. Along line 3-3, the micro-dimples formed generally have a depth of about 0.0195 mm. Figure 4The outer surface 22 is shown to be micro-pitted using #320 grit at 100 psi. The sandblasting using #320 grit can be performed alone or after the core mold has been sandblasted with #36 grit. Along line 4-4, the micro-pits formed generally have a depth of about 0.0100 mm. The deeper micro-pits reduce the static friction coefficient of the silicone rubber because, if the core mold is sandblasted with #36 grit, the core mold will be sandblasted with #36 grit. Figure 3 The sheet and Figure 4 As can be seen when comparing the sheet in FIG. 1 , there is less surface area of ​​the outer surface 22 to be contacted. Sandblasting can also be performed between #36 and #320 grit.

[0028] Alternative methods of forming the different depths of the dimples 24 include, but are not limited to, modifying the surface of the core mold by rolling, pressing the mold onto a textured surface, chemical etching, laser engraving, computer numerical control (CNC) engraving, electro-erosion (i.e., electrical discharge machining), electrodeposition, laser micro-melting, shot blasting, shot peening, and pinwheeling. Similar methods now known or to be discovered that are equivalent to the included method (i.e., a method of forming dimples on the outer surface of the silicone layer of a prosthetic liner) are also intended to be included in the above list.

[0029] Three tests were conducted to demonstrate the beneficial properties of the present invention, and the test results are as follows: Figure 5 As shown. In the first, the mold was sandblasted at 100 psi using #36 grit and the force required for pull resistance (i.e., before tearing) was 1.6 N. In the second test, the mold was sandblasted using #320 grit. The result was a force of 2.33 N for pull resistance. In the final test, the mold was not sandblasted at all and the force required was 9.33 N. The test was conducted on smooth stainless steel using a 1 inch wide and 7 inch long silicone strip while applying a 100 g weight.

[0030] The present disclosure includes what is contained in the appended claims and what is described above. Although the present invention has been described in its preferred form with a certain degree of particularity, it should be understood that the disclosure of the preferred form is made by way of example only, and that various changes may be made to the details of construction and the combination and arrangement of parts without departing from the spirit and scope of the present invention.

[0031] The present invention has now been described.

Claims

1. A method for manufacturing a silicone gasket, comprising: modifying the surface of the mandrel using a method selected from the group consisting of rolling, chemical etching, laser engraving, computer numerical control engraving, electro-erosion, electrodeposition, laser micro-melting, shot peening, shot peening, and windmilling; molding silicone on the core mold; A fabric sidewall is formed on the silicone to produce a composite, wherein the composite further includes an open upper end, a closed bottom end, and a fabric sidewall having a thickness, wherein the sidewall further includes a silicone inner layer having a silicone thickness, wherein the silicone has micropits having a depth between 0.0100 and 0.0195 mm.

2. The method for manufacturing a silicone gasket according to claim 1, wherein: The thickness of the side wall is between 1.5 and 3 mm.

3. The method for manufacturing a silicone gasket according to claim 1, wherein: The thickness of the silicone at the bottom end is between 3 and 12 mm.

4. The method for manufacturing a silicone gasket according to claim 1, further comprising: The tensile resistance before fracture is less than 2.4N of force.

5. The method for manufacturing a silicone gasket according to claim 1, wherein: The dimples are further formed by extruding silicone onto the textured surface after molding but before cooling.

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