METHOD OF MANUFACTURING A DISPOSABLE CERVICAL CAP

Abstract: The present invention relates to an improved method of manufacturing a disposable cervical cap by injection molding and cervical caps produced thereby. The method includes providing an injection point at a top portion location of a heated mold cavity and injecting an elastomeric molding material into the heated mold cavity at the injection point. The material flows downwardly throughout the mold cavity, producing a molded cap (10) having a substantially thickened annular rim (18) and a form-assuming dome (12) with a generally thickened top portion (20) having an interior and exterior surface and a substantially thin middle portion (22).

Description: 1 METHOD OF MANUFACTURING A DISPOSABLE CERVICAL CAP Background of the Invention 1. Field of the Invention The present invention relates generally to a method of manufacturing a disposable cervical cap and a cervical cap produced thereby, and, more particularly, to a method of molding a cervical cap according to a generally thick to substantially thin to a substantially thick system. 2. Discussion of the Related Art Cervical caps composed of silicone rubber are typically molded by a traditional thick to thin hot runner system. This system includes injecting molding material into a bottom section of the molding cavity, forming a molded part having a thickened bottom portion and thin top portion. The product, however, typically has a seam where the streams of flowing molded material meet in the mold cavity, resulting in a molded part having a particularly weak area. Additionally, this thick to thin system wastes up to about 23% of the molding material as a result of long inlet pipes or runs in which the material must travel to reach the mold. Thus, because of the nature of the material, the silicone material in the runners cannot be reused. The present invention provides an improved method of manufacturing disposable cervical caps which overcomes the aforementioned problems. The method of the present invention reduces the excess waste of molding material and produces a molded product with minimal stress seams. Summary of the Invention The present invention relates to an improved method of manufacturing a disposable cervical cap by injection molding. The method includes providing an injection point at a top portion location of a heated mold cavity and injecting an elastomeric molding material into the heated mold cavity at the injection point. The material then flows downwardly throughout the mold cavity, producing a molded cap having a substantially thickened annular rim and a form-assuming dome with a generally thickened top portion having an interior and exterior surface and a substantially thin middle portion. The method further includes the step of removing the molded cap from the mold cavity. The present invention also provides an improved disposable cervical cap comprising a thin, form-assuming flexible dome having an interior and exterior surface. The dome comprises a top portion having first and second sections and a base portion. The first section of the top portion of the dome is about 0.35 millimeters thick and the second section of the top portion is about 0.25 millimeters thick. The cap also includes a flexible, annular rim integrally-molded with the base portion of the dome, where the rim has an inner and outer surface. Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings. Brief Description of the Drawings FIG. 1 is a side view of a preferred embodiment of a cervical cap of the present invention; FIG. 2 is a top elevational view of the cervical cap; FIG. 3 is a sectional view, taken along line 3-3 in FIG. 2; FIG. 4 is a side view of an alternate preferred embodiment cervical cap of the present invention; and FIG. 5 is a sectional view, taken along line 5-5 in FIG. 4. Detailed Description of the Preferred Embodiment Generally thick to substantially thin to substantially thick injection molding at a top portion location of a mold cavity is an improved method in which to mold silicone rubber. Rather than injecting the silicone material into the bottom portion of the mold cavity or in the rim portion of the mold, the present invention provides a step of injecting elastomeric molding material, such as silicone rubber, at a top portion location of a heated mold cavity. The method produces a molded cap having a form-assuming dome with a generally thickened top portion having interior and exterior surfaces and a substantially thin middle portion. The method produces a more cost efficient and effective cervical cap that includes a generally thickened uppermost top section and a substantially thinner middle section comprising the remaining portion of the dome. The thickened uppermost portion of the apex of the dome is preferably about 0.35 ± 0.03 millimeters, while the remaining top portion of the dome is preferably about 0.25 millimeters, and most preferably about 0.22 ± 0.03 millimeters of silicone. The molded cap also includes a substantially thickened annular rim. By employing a thick to thin to thick system where elastomeric molding material is injected at a top portion location of a heated mold cavity producing a dome having a thickened top portion, the present invention utilizes substantially less molding material than traditional molding processes and results in a molded cervical cap with minimal seams. In addition, the use of a thickened top portion on the dome facilitates the removal of excess molding material at the injection point without damaging the dome integrity. The excess waste associated with injecting molding material at the bottom of the mold cavity or rim portion of the cervical cap is a result of the long inlet pipes or runs in which the material must travel to reach the mold. In a preferred embodiment of the present invention, the method further comprises a step of creating a reservoir at the top portion location for storing molding material as it is injected into the top portion location of the molding cavity. The reservoir allows the injected molding material to pool and remain warm, building up the pressure necessary to cause the material to flow throughout the cavity before the material hardens. The reservoir is preferably formed by thickening the interior surface of the top portion of the molded cap. Alternatively, the reservoir is formed by thickening the exterior surface of the top portion. The cervical cap produced by the method of manufacturing of the present invention preferably is a thin-walled, flexible, and pliant dome with an integrally-molded flexible retaining rim. In position, the flexible dome of the cervical cap conforms to the exocervical surface to closely fit the cervix upon contact. Due to its thinness and pliability, the dome of the cap will continue to adhere to the surface of the cervix until removed. Adherence to the dome of the cervix is further facilitated by the moist cervical surface. The cervical cap produced by the process of the present invention may be employed as a contraceptive, or alternatively, as a conception device, depending on the desired result. The contraceptive device functions to prevent semen from entering the cervical canal (Os), while the conception device aids in fertilization when sperm is placed inside the cap and the device is placed over the cervix, thereby concentrating sperm at the opening of the Os. Referring to FIG. 1 , a preferred embodiment of a cervical cap of the present invention is illustrated and indicated generally by the numeral 10. Generally speaking, cervical cap 10 comprises a flexible, thin, form- assuming dome 12, a top portion 14, a base portion 16, and an annular rim 18. Dome 12 is generally thimble-shaped, with base portion 16 inwardly tapering toward top portion 14. The outer diameter of rim 18 is greater than that of base portion 16 of dome 12. Dome 12 further includes a thickened first section 20 and a second section 22. First section 20 is an inactive or non-functional area of the dome, while second section 22 is an active area that most effectively functions as the gripping portion of the dome to the cervix. The second section is preferably less than about one-third of a millimeter, most preferably less than about 0.25 of a millimeter, and still more preferably about 0.22 millimeters thick. The thickened first section is preferably about 0.35 millimeters thick. In an alternate preferred embodiment, the cervical cap 10 further includes a loop 28 that serves as a handle, facilitates insertion and removal of cap 10, and is integrally-molded with annular rim 18. In an additional preferred embodiment, referring particularly to FIGS. 2 and 3, annular rim 18 has an inner surface 24 and an outer surface 26. Thin, gripping finger 30 projects upwardly and outwardly, as finger 30 is integrally-formed with inner surface 24. Finger 30 also defines an upper portion of a notched indentation 32 as viewed in FIG. 3. Annular rim 18 contains at least two gripping fingers 30 that are directly opposite or symmetrically opposed from each other along inner surface 24. However, it will be appreciated to one skilled in the art that more than two fingers could be employed. Fingers 30 effectively grip and hold cervical cap 10 over the cervix in order to prevent semen from entering the cervical canal or to aid in fertilization, depending on the desired result. Gripping fingers 30 and notched indentation 32 essentially provide the effect of a Chinese finger puzzle by gripping the side walls of the cervix and holding the cap when the circumference of the rim 18 is fitted around the cervix and slightly expands. Cervical cap 10 is fixed in place by the use of gripping fingers 30 rather than merely by suction or surface viscosity. Referring now to FIGS. 4 and 5, an alternate embodiment of the present invention provides a cervical cap 110 comprising a flexible, thin, form- assuming dome 112, an apex portion 114, a base portion 116, and an annular rim 118. Dome 112 is generally thimble-shaped, with base portion 116 inwardly tapering toward apex portion 114. The outer diameter of rim 118 is greater than that of base portion 116 of dome 112. Dome 112 further includes a thickened first section 120 and a second section 122. First section 120 is an inactive or non-functional area of the dome, while second section 122 is an active area that most effectively functions as the gripping portion of the dome to the cervix. The second section is preferably less than about one-third of a millimeter, most preferably less than about 0.25 of a millimeter, and still more preferably about 0.22 millimeters thick. The thickened first section is preferably about 0.35 millimeters thick. Referring particularly to FIG. 5, rim 118 has an inner surface 124 and an outer surface 126, bottom surface 128, and upper surfaces 130 and 132. Upper surface 130 extends leftward from base portion 116, as viewed in FIG. 5, and terminates at outer shoulder 134. Upper surface 132 extends rightward from base portion 116, as viewed in FIG. 5, and terminates at outer shoulder 136. Upper surface 132 extends at an acute angle from adjacent base portion 116, preferably, for example, at about an 85 degree angle. Annular rim 118 has generally inwardly directed annular groove 138. The side walls or annular groove 138 extend generally toward bottom surface 128 with the opening of annular groove 138 facing inwardly and upwardly as shown in FIG. 5. Adjacent to annular groove 138 are annular upper rim 140 and annular lower rim lip 142. As illustrated in FIG. 5, both upper rim lip 140 and lower rim lip 142 extend generally inwardly and upwardly at an angle acute to dome base portion 116. This lip configuration serves to grip the cervix wall and helps keep the cervical cap in position over the cervix as an alternate embodiment to the configuration shown in FIGS. 2 and 3. In a further preferred embodiment, cervical cap 110 includes a loop 144 that serves as a handle, facilitates insertion and removal of cap 110, and is integrally-molded with annular rim 118. It is preferred that the cervical cap of the present invention be constructed of a sperm-impermeable, tear-resistant medical elastomer, such as a silicone rubber, and formed by liquid injection molding. Other suitable materials, such as RTV thermoplastic that can be molded thin enough to be form-conforming and pliant may also be employed. Preferred materials include a 40 durometer silicone, such as Silastic Q4840 (Dow Corning) or Silicone 4040 (Bayer). When thinly molded, these materials allow for up to a 600% stretch of the molded product. The elastomer material may or may not be impregnated with biologically active components. These components may include, but are not limited to, spermicides, antibiotics, antifungals, and hormonal replacements. For example, to increase its contraceptive effect, the cervical cap of the present invention may be pre-treated by coating or impregnating its surface with spermicidal agents during manufacture. The biologically active components may also assist in fertilization, or may be mixed with sperm within the hollow body of the dome of the cap in order to achieve the desired result. The use of biologically active materials may stimulate sperm motility, prolong the active life of the sperm or aid in gender selection. Selectively eliminating or altering the behavior of some sperm by significantly changing the pH may bias the activity of the X or Y sperm, resulting in odds which favor one particular sex over the other. These components may be released therefrom in an amount effective to achieve its purpose during use. Although the description as set forth is in conjunction with human subjects, it will be further appreciated that the claimed products and methods may be readily adaptable for use with animal subjects having a cervix. While it will be apparent that the preferred embodiments disclosed are well calculated to provide the advantages and features above stated, it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope or fair meaning of the subjoined claims.

Claims: We Claim: 1. An improved method of manufacturing a disposable cervical cap comprising the steps of: (a) providing an injection point at a top portion location of a heated moid cavity; (b) injecting an elastomeric molding material into said heated mold cavity at said injection point, wherein said material flows downwardly throughout said mold cavity, producing a molded cap having a substantially thickened annular rim and a form-assuming dome with a generally thickened top portion having an interior and exterior surface and a substantially thin middle portion; and (d) removing said molded cap from said mold cavity. 2. The method of claim 1 further comprising the step of creating a reservoir at said top portion location for storing molding material. 3. The method of claim 2 wherein a reservoir is created by thickening said interior surface of said top portion of said molded cap. 4. The method of claim 2 wherein a reservoir is created by thickening said exterior surface of said top portion of said molded cap. 5. The method of claim 1 wherein said thickened top portion is about 0.35 millimeters thick. 6. The method of claim 1 wherein said substantially thin middle portion is about 0.25 millimeters thick. 7. The method of claim 1 wherein said substantially thin middle portion is about 0.22 millimeters thick. 8. An improved disposable cervical cap comprising: (a) a thin, form-assuming flexible dome having a hollow body and an interior and exterior surface, said dome comprising a top portion having first and second sections, and a base portion; and (b) a flexible, annular rim integrally-molded with said base portion and having an inner and outer surface; wherein said first section of said top portion of said dome is about 0.35 millimeters thick and said second section of said top portion is about 0.25 millimeters thick. 9. The cervical cap of claim 8, wherein said second section is about 0.22 millimeters thick. 10. The cervical cap of claim 8, wherein said cap further comprises at least two thin, gripping fingers projecting upwardly and outwardly, said fingers being integrally-formed with said inner surface of said rim, wherein said fingers are symmetrically opposed from each other along said inner surface of said rim, and wherein each said finger defines a notched indentation in said inner surface of said rim in order to effectively grip and hold said cap over said cervix. 11. The cervical cap of claim 8, wherein said annular rim further comprises an inner and outer surface and a bottom surface, said inner surface having an annular groove descending acutely from an inner wall toward said bottom surface of said rim, whereby said annular groove defines an ascending lip on said inner surface of said rim. 12. The cervical cap of claim 11 , wherein said rim includes an outer shoulder beveled with respect to said exterior surface of said dome. 13. The cervical cap of claim 8, wherein said cap further comprises a loop integrally-molded to said annular rim. 10 14. The cervical cap of claim 8, wherein said cap is comprised of a sperm-impermeable medical elastomer. 15. The cervical cap of claim 8, wherein said cap is comprised of silicone rubber. 16. The cervical cap of claim 8, wherein said cap is comprised of a biologically active material. 17. The cervical cap of claim 8, wherein said cap further comprises sperm within said body of said dome. 18. The cervical cap of claim 8, wherein a biologically active material is mixed with sperm within said hollow body of said dome. 19. The cervical cap of claim 8, wherein said cap is of a size suitable for use with a human. 20. The cervical cap of claim 8, wherein said cap is of a size suitable for use with an animal.

Inventors: LAVEAN MICHAEL G, LAVEAN, MICHAEL, G.
Applicants: LAVEAN MICHAEL G, VEOS FRANCE EURL, LAVEAN, MICHAEL, G.
Application year: 1998
Main classification: A61F6
IPC codes: A61F6, B29C45