Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating
Reexamination Certificate
1999-06-14
2001-07-10
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
C249S117000, C264S002500, C264S102000, C425S808000
Reexamination Certificate
active
06258299
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for molding ocular lens material and a molding method employing the same. More particularly, the present invention relates to a device for molding ocular lenses such as intraocular lenses or contact lenses or for molding ocular lens material of shapes corresponding to precursors thereof by polymerizing monomer compositions for providing polymer products constituting these articles within a molding cavity, and it also relates to a method for molding targeted ocular lens material by performing polymerizing of specified monomer compositions within the molding cavity by employing the above device.
BACKGROUND ART
It has been conventionally known that ocular lenses such as intraocular lenses or contact lenses as well as ocular lens material of shapes corresponding to precursor thereof might be formed through various methods such as mechanical processing such as cutting or grinding materials of polymer products constituting these articles having specified shapes (rod-like bodies, blocks, etc.). Alternatively, they might be formed through so-called mold polymerization in which monomer compositions providing polymer products are polymerized within a molding cavity of a specified molding device (molding dies) to obtain a molded article having a shape corresponding to the molding cavity.
Japanese Unexamined Patent Publication No. 52168/1995 discloses one example for obtaining targeted ocular lens material through such a mold polymerization method. As shown in
FIGS. 1
to
3
, this publication discloses a method for obtaining ocular lens material of polymer products by immersing molding dies composed of an upper die and a lower die within a monomer solution accumulated in a vessel and by polymerizing the monomer solution within a molding cavity formed between the upper die and the lower die through a radiant flux introduced through the upper die, thereby obtaining ocular lens material of polymer product corresponding to the shape of the molding cavity. In this invention, the upper die needs to be reliably shielded such that leakage of radiant flux that is passed through the upper die does not occur so as to prevent polymerization of monomer solution being present in the periphery of the molding dies, and the upper die needs to be detached from the lower die after the polymerization. Such various devises as explained above that need to be taken various designs for the molding dies result in a difficult die arrangement. Additionally, since molded ocular lens material need to be taken out from the monomer solution after the polymerization, residues of such monomers need to be removed from the ocular lens material wherein such operations might be quite troublesome. Still further, one or more of monomers might volatilize from the monomer solution residing in the periphery of the molding dies at the time of polymerization, whereby variations in the composition of the monomer solution and thus in the composition of the obtained ocular lens material would be caused.
Further, the method and device for manufacturing optical lenses as disclosed in Japanese Unexamined Patent Publication No. 256658/1995 employs dies for molding that can be repetitively utilized wherein either one of two mold halves (half dies) is made to be moveable like a piston and wherein a specified molding cavity is formed between the two mold halves. In order to obtain targeted contact lenses (optical lenses), the molding cavity is filled with the monomer composition wherein air within the molding cavity is eliminated while injecting a specified monomer composition into the molding cavity formed between the two mold halves by means of, for instance, an injecting nozzle, for polymerization. Also in this method, the arrangement of a moving mechanism for one of the mold halves and an injection mechanism for monomer solution makes the die arrangement complicated. Further, shrinkage accompanying the polymerization of monomer solution within the molding cavity would be difficult to be effectively compensated since a capacity of a flow outlet at which the injected monomer solution is substantially resident is insufficient, and consequently, the flowability of the monomer solution within the molding cavity becomes poor so that the shapes of obtained contact lenses might not be uniform. In other words, supply of monomer solution to the molding cavity interior, that is, the molding surfaces, becomes insufficient so that unevenness of surfaces of obtained molded articles (contact lenses) might be caused, resulting in failure of targeted lens surfaces.
The present invention has been made in view of such circumstances, and its subject for solution lies in the point to achieve simplification of die arrangement in a device for molding ocular lens material through mold polymerization, to improve the flowability of monomer compositions of the ocular lens components at the time of polymerization shrinkage, and to make surfaces of the obtained ocular lens materials uniform by improving the transcriptability of the molding cavity interior (molding surface) through supplying ocular lens components to the molding cavity in an uniform manner.
DISCLOSURE OF THE INVENTION
In order to solve such problems, the present invention provides a device for molding ocular lens material which is (a) a device for molding ocular lens or ocular lens material of shapes corresponding to precursors thereof by polymerizing liquid monomer composition of polymer products constituting these articles within a molding cavity, characterized in that it comprises (b) a cylindrical main body having a hollow hole in which the monomer composition is accumulated, (c) a lower die composed of a lower die base portion disposed in a lower portion of the hollow hole as to close a lower aperture of the hollow hole of the cylindrical main body, and a lower die columnar portion that is erected as to extent upward from an upper surface of the lower die base portion within the hollow hole and of which tip surface is formed with a lower die molding surface corresponding to one surface of the ocular lens material, wherein a periphery of the lower die columnar portion is spaced, (d) an upper die composed of a plate-like upper die base portion that is fitted into an upper portion of the hollow hole of the cylindrical main body for parting the hollow hole into two, forming an intermediate chamber between itself and the lower die base portion of the lower die into which the monomer composition is filled, and forming an exterior accumulating chamber on a side of an upper aperture of the hollow hole into which the monomer composition is accumulated, and an upper die columnar portion that is erected as to extent downward from a lower surface of the upper die base portion within the hollow hole and of which tip surface is formed with an upper die molding surface corresponding to another surface of the ocular lens material, wherein a periphery of the upper die columnar portion is spaced, wherein the molding cavity is formed between the upper die molding surface of the upper die columnar portion and the lower die molding surface of the lower die columnar portion, and wherein a communicating portion is formed over a whole circumferential of an exterior circumferential portion of the molding cavity through which the monomer composition is introduced from the intermediate chamber to the molding cavity, and (e) not less than three piercing holes for introducing the monomer composition from the external accumulating chamber to the intermediate chamber that are provided as to pierce the upper die base portion of the upper die in a vertical direction and as to be positioned at equal intervals around the upper die columnar portion.
In the device for molding ocular lens material according to the present invention, the monomer composition is introduced into the intermediate chamber through not less than three piercing holes provided in the upper die base portion of the upper die, and is further introduced into the molding cavity for filling. On the other
Kawaguchi Tohru
Ojio Tatsuya
Yamashita Keiji
Armstrong Westerman Hattori McLeland & Naughton LLP
Menicon Co. Ltd.
Vargot Mathieu D.
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