Patent Publication Number: US-7220120-B2

Title: Molds and method of using the same for forming plus or minus lenses

Description:
RELATED APPLICATION 
     This patent application is a Continuation-In-Part of U.S. patent application Ser. No. 10/992,225, entitled “Molds and Method of Using the Same for Forming Plus and Minus Lenses,” filed on Nov. 18, 2004. The aforementioned patent application is expressly incorporated herein, in its entirety, by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention encompasses, in part, a method and apparatus for lens casting in which two molds, preferably formed of plastic, are interconnected or joined together via a ring to form a mold cavity having substantially the same dimensions of the lens to be formed therein. The invention is further directed to compositions and methods used in lens casting. 
     2. Background 
     The art of casting lenses involves introducing a lens-forming material, such as a monomer or monomer mixture, into a volume and then polymerizing the lens-forming material to become a solid. The formed lens can be used for ophthalmic or specialty optics applications. Ophthalmic devices have traditionally been created by first forming a cavity out of two separate mold shapes, then filling that cavity with a liquid material that will cure and form a solid shape. The molds used in this type of process are typically glass or metal, based on their high chemical resistance and low amount of geometric distortion they experience over time. 
     Most commonly, two glass mold pieces and a gasket form the volume that defines the dimensions of the lens to be cast. Some prior art gaskets are known as “T-gaskets,” which include a bore having two ends that each complementarily receives a respective glass mold spaced apart a predetermined axial distance from the other mold. Different T-gaskets are required to form varying power lenses because they only allow one separation distance between molds. Accordingly, manufacturers must maintain T-gaskets for a +2 lens, another for a −3 lens, still another for a −4 lens, etc. 
     An improvement of this “T-gasket” design is disclosed in U.S. Pat. No. 6,068,464 (hereafter “the &#39;464 patent”), in which at least one of the two molds is slidably movable along the bore of the gasket. This design thus has a “universal” gasket that can be used to form different powers of lenses, whereas a given prior art T-gasket may be used to form one power of lens and a different T-gasket is used to form another power. 
     U.S. Pat. No. 5,551,663 (hereafter “the &#39;663 patent”) described the use of plastic molds in the manufacture of ophthalmic lenses, but no mention of successfully making lenses is included here. This approach necessitated the use of a “protective coating” first being applied to the mold before the mold could be used. This protective coating became a permanent part of the mold, and allowed for the mold to be used repeatedly. Evidence of the permanence of the coating is apparent in the description of the adhesion test used to assure proper adhesion of the coating to the mold. The patent describes a “plastic mold having an adherent, abrasion resistant, release enhancing face.” The purpose of the coating of the &#39;663 patent is to prevent attack of the mold by the lens material. (By comparison, this current patent application applies a coating to the mold, but with the intent that the coating be only temporary, and that it transfer via chemical or physical bonding to the lens material.) 
     The method of the &#39;663 patent raises significant issues about its ability to consistently produce high-quality molded lenses. Possible problems that might occur with the method of the &#39;663 patent include a decay in the optical quality of the mold. Any defect on either side of the mold could affect the finished quality of the lens. The decay can take the form of yellowing, cracking, scratching, and physical deformation. These forms of decay can occur with repeated use of a non-rigid material. Any of these types of decay could alter the optical quality of lenses made. Additionally, plastic materials would be difficult to clean, since they are not very chemically resistant, not scratch resistant, and not very resistant to the heat used in many typical processes. 
     Accordingly, a need exists for durable, low cost plastic molds that can be used to create lenses of various powers. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a method and apparatus for casting a lens, and chemical compositions used to perform the same. 
     In one implementation of the invention, a front mold and a rear mold formed of a plastic are joined together or interconnected via a ring to form a mold cavity having substantially the same dimensions of the lens to be cast. Stated differently, surfaces of the ring and front and rear molds collectively define a volume known as the mold cavity, which is a negative image of the lens to be formed therein. 
     More specifically, the front mold has a lens-forming surface and an edge circumscribing the lens-forming surface. The rear mold similarly has a lens-forming surface and an edge circumscribing its lens-forming surface. The lens-forming surfaces of the front and rear molds are each of a size to be complementarily received by and within the interior periphery of the ring. The molds have backing members, which stop the insertion of molds when their respective lens-forming surfaces reach a predetermined point within the ring so that the spacing between the two lens-forming surfaces is at a desired separation distance. This desired separation corresponds to the thickness of the mold cavity, which dictates the thickness and power of the lens formed by the casting device. 
     The molds of the present invention may be designed to cast lenses of different strengths and curvatures. That is, for a lens with given optical surfaces, the lens thickness can be altered by manufacturing the front and/or rear molds having their backing member at one of a plurality of distances from the respective lens-forming surface. Alternatively, the length or height of the ring may be changed to vary the thickness of the mold cavity. Another alternative is to include a plurality of protrusions adjacent the edge of one of the lens forming surfaces, in which the height of the protrusions establishes the edge thickness of the mold cavity. 
     The present invention additionally allows for a disposable plastic mold to be used in the ophthalmic casting process, either with the disclosed apparatus or in other systems known in the art. This disposable mold can be made out of a variety of amorphous thermoplastics, and can be used to make a lens with or without a variety of coating scenarios. The lenses formed using this process are impact resistant, can have any refractive index, can be clear (no tint) or photochromic, and can be used for “dress” or safety purposes. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an exemplary embodiment of a casting system used with the present invention. 
         FIG. 2A  is side cross-sectional view of the front mold shown in  FIG. 1 , which is preferably used to form a minus lens. 
         FIG. 2B  is an alternative design of the front mold shown in  FIG. 2A , which is preferably used to form a plus lens. 
         FIG. 2C  is side cross-sectional view of the rear mold shown in  FIG. 1 . 
         FIG. 3A  is a side cross-sectional view of the components in  FIG. 1  assembled. 
         FIG. 3B  is an alternative design of the casting system shown in  FIG. 3A , in which the front mold of  FIG. 2B  is included. 
         FIG. 4A  is a lens formed by the casting system shown in  FIG. 3A . 
         FIG. 4B  is a lens formed by the casting system shown in  FIG. 3B . 
         FIG. 5  is a perspective view of the casting system of  FIG. 1  connected to a fill bag containing monomer. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is more particularly described in the following detailed description, including examples. These examples are intended as illustrative of the invention, and numerous modifications and variations therein will be apparent to those skilled in the art while staying within the scope of the invention. As used in the specification and in the claims, “a,” “an,” or “the” can mean one or more, depending upon the context in which it is used. 
     A first embodiment is now described with reference to the figures, in which like numbers indicate like parts throughout the figures. The present invention comprises a molding or casting device  10  and an associated method that may be used to form lenses of various powers and geometric shapes, such as spectacle lenses. The present invention additionally comprises methods for making ophthalmic lenses using disposable plastic molds. 
     In this discussion, first one exemplary embodiment of a casting system comprising plastic components is discussed in the context of the components and method of those components. This first discussion provides context for and is followed by the aspects of the present invention that involve casting ophthalmic lenses using plastic molds. This latter discussion is not intended to be limited to the exemplary embodiment of the casting system disclosed herein. 
     Lens Casting Devices 
     Referring now to  FIGS. 1-5 , the casting device  10  of the present invention includes a front mold  20  and a rear mold  40 , both of which are preferably formed of plastic. The casting device  10  also includes a ring  50 , which may also be referred to as a sleeve or gasket. The ring  50  is also preferably formed of plastic and has opposed ends  52 , an interior periphery  54 , and an exterior periphery  56 . As discussed below, portions of the front and rear molds  20 ,  40  are complementarily received by and into the interior periphery  54  to form a mold cavity  60 . 
     The front mold  20  has a lens-forming surface  22 , an edge  28  circumscribing the lens-forming surface  22 , and a base  30  having dimensions greater than the interior periphery  54 . The edge  28  circumscribing the lens-forming surface  22  is sized to be complementarily received within a portion of the interior periphery  54  of the ring  50  and preferably form a substantially liquid-tight seal therebetween. The edge  28  is slidably received within the interior periphery  54  of the ring  50  until the base  30  abuts the end  52  into which the edge  28  was inserted. 
     The rear mold  40  likewise has a lens-forming surface  42 , a rim  46  circumscribing the lens-forming surface  42 , and a flange  48  having dimensions greater than the interior periphery  54  of the ring  50 . The rim  46  is also sized to be complementarily received within the interior periphery  54  of the ring  50 , which occurs until the end  52  of the ring  50  abuts the flange  48 . The rim  46  and the interior periphery  54  also preferably form a substantially liquid-tight seal therebetween. 
     As shown in  FIGS. 3A and 3B , when the edge  28  of the front mold  20  and the rim  46  of the rear mold  40  are both received by the respective ends of the ring  50 , the lens-forming surfaces  22 ,  42  of the front and rear molds  20 ,  40  and the ring  50  form a mold cavity  60  which has dimensions of a desired lens formable therein. That is, the mold cavity  60  is a replica image of the lens to be formed and has a volume defined by the ring  50 , front mold  20 , and rear mold  40 . 
     To form a lens once the ring  50  and front and rear molds  20 ,  40  are properly joined or positioned together, a resin, such as a monomer or other lens-forming fluid, is added or injected into the mold cavity  60  and cured. To that end, the ring  50  defines a feed opening  70  and a vent opening  72  therethrough, which are shown in  FIGS. 1 and 5 . The vent opening  72  provides fluid communication from the mold cavity  60  to outside of it (i.e., to ambient). 
     As best shown in  FIGS. 1 and 5 , when the front and rear molds  20 ,  40  are disposed upright, then the mold cavity  60  is substantially circular in plan view and the vent opening  72  is positioned at approximately the top center (the 12:00 o&#39;clock position). The feed opening  70  is preferably offset from the vent opening  72 , and one contemplated range for this offset is by approximately fifteen to sixty degrees (15°-60°). Still referring to  FIGS. 1 and 5 , it will be noted that an extender  74  is joined to the feed opening  70 . The top of the extender in communication with the feed opening  70  and is elevationally above the vent opening  72 , which ensures that the cavity is full when the monomer reaches the top of the extender  74 . It will further be noted that preferably the feed opening  70  is an elongated slot that extends across the width of the ring  50 . This design ensures that communication exists with the mold cavity  60  through the feed opening  70  regardless of the placement of the molds relative to the ring, which may change when used for casting minus lenses verses plus lenses. 
     A key dimension of the formed mold cavity  60  is its thickness. For minus lenses used for nearsightedness or myopia shown for example in  FIG. 4A , the center thickness is an important parameter, and it must satisfy impact testing required in the United States. As an example, plastic lenses formed of CR39 (which includes methyl-methacrylate—a thermoplastic resin better known by its trademark “Plexiglas”® or “Perspex”®—and diallyl glycol carbonate) must have a center thickness of at least two millimeters (2 mm). The preferred embodiment of the present invention is designed to be able to form both plus and minus lenses that satisfy these respective criteria. 
     First with regard to minus lenses, the center thickness is obtained by the design of the front and rear molds  20 ,  40  in conjunction with the width or length of the ring  50 . Referring now to  FIG. 2A  and addressing the front mold  20 , its base  30  has a contacting surface  32  that is substantially planar, and that contacting surface  32  abuts one end  52  of the ring  50  when the edge  28  of the front mold  20  is inserted therein to define a portion of the mold cavity  60 . In conjunction, the lens-forming surface  22  of the front mold  20  is concave and defines a nadir  26  or low point, which tangentially intersects a plane FMP defined by the contacting surface  32  of the base  30 . The nadir  26  of the lens-forming surface  22  is thus at the same relative height as the contacting surface  32  when the front mold  20  is horizontally disposed. As such, the nadir  26  is aligned with the end of the ring  50  when the contacting surface  32  abuts the end  52  of the ring  50 . 
     As shown in  FIG. 2C , the flange  48  of the rear mold  40  has an engaging surface  49  that is substantially planar to abut the respective end  52  of the ring  50  when the mold cavity  60  is formed. The lens-forming surface  42  of the rear mold  40  has an apex  44 , in which a plane AP tangential to the apex  44  is substantially parallel to and spaced apart from a plane RMP defined by the engaging surface  49 . The separation or distance between the plane AP tangential to the apex  44  and the plane RMP defined by the engaging surface  49  is called the back mold apex height AH. 
     Also, the opposed ends  52  of the ring  50  are spaced apart by a ring height RH. As one skilled in the art appreciates, the ring height RH establishes the separation between the engaging surface  49  of the rear mold  40  and the contacting surface  32  of the front mold  20 . Correspondingly, the ring height RH is a parameter used to set the center thickness of the mold cavity  60 , and thus the lens formed therein. That is, for this embodiment, the center thickness of the mold cavity  60  equals the ring height RH minus the back mold apex height AH, as the nadir  26  of the lens-forming surface  22  of the front mold  20  is aligned with one end of the ring  50 . Thus, if the ring height RH is three millimeters (3 mm) and the back mold apex height AH is two millimeters (2 mm), then the center thickness—the separation between the apex  44  of the rear mold  40  and the nadir  26  of the front mold  20 —is one millimeter (1 mm). 
     As shown in  FIG. 3A , the assembled casting device  10  shows the relative position of the components in establishing the center thickness for the mold cavity  60 . Specifically, one end  52  of the ring  50  abuts the contacting surface  32  of the front mold  20  and the opposed end  52  abuts the engaging surface  49  of the rear mold  40 . The nadir  26  of the front lens-forming surface  22  is spaced apart a desired distance—the center thickness—from the apex  44  of the rear lens-forming surface  42  when the molds  20 ,  40  are coupled together. Stated differently, the plane AP tangential to the apex  44  is spaced apart from the plane FMP defined by the contacting surface  32  and tangentially intersects the nadir  26  at a distance substantially equivalent to the desired center thickness of the mold cavity  60 . Thus, the apex  44  and the nadir  26  of the respective lens-forming surfaces  22 ,  42  in the mold cavity  60  are spaced apart at the desired center thickness for the lens to be formed. 
     As one skilled in the art appreciates, changing the dimensions of the components correspondingly alters the center thickness of the mold cavity  60 . Any of the components can be modified. Although viable, currently the least desirable option is to change the position of the nadir  26  relative to contacting surface  32  of the front mold  20 . A more desirable option is using rings  50  each having a different ring height RH to change the center thickness. The presently preferred design, however, is to vary the back mold apex height AH among different molds to change the center thickness of the mold cavity  60 . Thus, in this latter design, the front mold  20  uses the same design shown in the illustrated embodiment and a “universal” or “one-size” ring that has the same dimensions regardless of the strength of the lens to be made; only the rear mold  40  is changed in this latter design and, in particular, the back mold apex height AH is altered among different rear molds  40  to vary the center thickness of the mold cavity  60 . 
     Still another contemplated embodiment to change the center thickness for a selected ring  50 , front and rear mold  20 ,  40  is to include a circular spacer (not shown) between the engaging surface  49  of the rear mold  40  and respective end of the ring  50 . The circular spacer has diameter the same as the ring  50  and a fixed width or height, thereby increasing the center thickness of the mold cavity  60  by that width of the circular spacer. For example, a circular spacer having a width of one millimeter (1 mm) disposed between the end of the ring  50  and the engaging surface  49  would correspondingly result in the center thickness of the mold cavity  60 —and lens to be formed therein—increasing by one millimeter (1 mm). Circular spacers, accordingly, may reduce the number of components that need to be manufactured to enable an operator to cast all desired dimensions and strength of lenses. 
     Referring now to  FIGS. 2B and 3B , the illustrated front mold  20  includes a plurality of protrusions  34  located adjacent the edge and space apart from each other. The protrusions  34  have a height corresponding to a desired edge thickness for the mold cavity  60 . For example, if the protrusions  34  have a height of one millimeter (1 mm), then the edge thickness of mold cavity  60  will be at least one millimeter because the protrusions  34  prevent the edges of the front and rear lens-forming surfaces  22 ,  42  from being closer together than the height of the protrusions  34 . The protrusions  34  may be any desired height, including for example 0.75, 1.0, 1.25 millimeters and the like. A person skilled in the art can determine the number of protrusions  34  to use; the currently contemplated embodiment uses thirty-two equally spaced protrusions  34  circumscribing the perimeter of the lens-forming surface  22  of the front mold  20 . Fewer protrusions are shown in the drawings for simplicity. It will be appreciated that benefits of this design include the same rear molds  40  and rings  50  that are used to form the minus lenses also being used to form the plus lenses. 
     The present invention additionally contemplates other methods of forming plus lenses. For example, the ring height RH may be varied to obtain the correct separation between the lens-forming surfaces  22 ,  42  of the front and rear molds  20 ,  40 , including the edge thickness. Also, the lens-forming surfaces  42  of the rear molds  40  may include the protrusions  34  instead of the front molds, but this option is less desirable given the greater variations in rear mold designs and associated higher cost for a “library” of molds to manufacture all lens variations. 
     In addition to considering the edge of center thickness, another relevant parameter in forming a desired lens is the geometric configuration or relationship of its two optical surfaces. When the two lens-forming surfaces  22 ,  42  are both spherical, the molds  20 ,  40  do not require any special rotational alignment relative to each other. This is because the respective surfaces have a constant radius along their different axes resulting in the surfaces being symmetric relative to each other. 
     For other lenses, however, the present invention includes a means for orienting the front and rear molds  20 ,  40  at a predetermined rotational position with respect to each other. In the illustrated embodiment, the front and rear molds  20 ,  40  are rotatably movable relative to each other so that the two molds may be positioned at one of a plurality of selected relative rotational orientations. This orienting means thus allows the operator to alter the dimensions or shape of the mold cavity  60  to desired values when either or both of the lens-forming surfaces  22 ,  42  of the front and rear molds  20 ,  40  have asymmetric curvature. Examples of asymmetrical lenses that operators may typically cast include the front surface of a lens being spherical with an add power—or less frequently being a plano surface—and, in conjunction or independently, the back surface being cylindrical or toric. A discussion of the features and types of such asymmetrical surfaces may be found in U.S. Pat. No. 6,103,148. 
     Referring back to  FIG. 1 , the present invention also comprises an aligning means to allow the operator to appreciate the relative rotation of the two molds  20 ,  40  and position them accordingly. The aligning means shown in the illustrated embodiment comprises axis marks  90  on the exterior periphery  56  of the ring  50  and an axis-positioning indicator  92  on the front mold  20  or rear mold  40  or both. The axis marks  90  extend from 0° to 180° and the asymmetrical lens-forming surface  22  or  42  is to be positioned in registry with them. If injection molding or similar technique forms the components, the aligning means are preferably etched or formed into the respective dies. Thus, the position indicator  92  and marks  90  are also integrally formed into the components. One skilled in the art will also appreciate that aligning means may alternatively comprise the axis marks being located on one or both of the front and rear molds  20 ,  40  and an axis-positioning indicator on the ring  50 . Other methods of visually indicating the rotational position of the molds relative to each other may also be used. 
     In preparing to cast the lens, the operator locates the position indicator  92  at a desired orientation relative to the axis marks  90  on the ring  50  either before the front and rear molds  20 ,  40  are joined to the ring  50  or afterwards (e.g., twisting the molds relative to each other once they are coupled to the ring  50 ). The operator, thus, is able to position the two molds at a desired rotational location easily using the aligning means. 
     When the operator joins the ring  50  and the two molds  20 ,  40  together after selecting them, it is preferred that a connecting means exists so that the components do not inadvertently separate during the lens casting process. Such a connecting means can take numerous forms known in the art, including the interior periphery  54  of the ring  50  and the edge  28 /rim  46  having a tight frictional fit. Other connecting means are also contemplated (not shown), including designs in which the two molds  20 ,  40  snap into place within the ring  50  or in which an external clip or containing device is used to hold the components together. 
     In still another contemplated embodiment, the front and rear molds  20 ,  40  are formed as a single unit so they are integrally joined to each other. This may occur during the forming process (i.e., during injection molding) so that the operator receives a preformed molding structure in which the front and rear molds  20 ,  40  are stationarily positioned relative to each other. This unitary design, however, has less flexibility than interchanging the ring  50  and the front and rear molds  20 ,  40 . 
     As noted above, once the front and rear molds  20 ,  40  are stationarily positioned together, a resin, such as a monomer or other lens-forming fluid, is added or injected into the mold cavity  60  and cured via the feed and vent openings  70 ,  72  through the ring  50 . Referring now to  FIG. 5 , a fill bag  80  or the like containing a fluid such as monomer may be interconnected to the feed opening  70  or its extender  74 . More specifically, the fill bag  80  has an interior and an injection port  82  detachably connectable to the feed opening  70 . When the injection port  82  is linked to the feed opening  70 , the monomer located within the interior of the fill bag  80  may flow through the port into the mold cavity  60 . 
     The injection port  82  and the feed opening  70  are preferably designed to complementarily engage each other. That is, the tip  84  of the injection port  82  is of a size to be complementarily received within the feed opening  70  or its extender  74  to form a fluid-tight seal therebetween. 
     One consideration that a person skilled in the art takes into account in casting lenses is the flow characteristics of the monomer traversing from the fill bag  80  into the mold cavity  60 . A primary concern is to avoid the introduction of air bubbles and ensure that any such bubbles escape from of the mold cavity  60  before the curing begins; otherwise, the formed lens may be unacceptable if an air bubble discontinuity exists in the final product. In addressing this issue, the size of the feed opening  70  should be of a dimension and positioned to promote laminar flow when filling the mold cavity  60 . The fill opening  70  is preferably oriented to direct the monomer along the side of the mold cavity  60  during the initial filling. As noted above, the vent opening  72  is also preferably located at the top of the mold cavity  60  (i.e., at the 12:00 o&#39;clock position) to vent air within the cavity  60  when displaced by the injected or incoming monomer. The vent opening  72  being located at the top also allows any bubbles to escape before the curing process begins. 
     Another consideration regarding injecting monomer involves positioning the mold cavity  60  so that the add power (not shown) is oriented to have its flat top portion substantially upright or vertical during filling the mold cavity  60 . This orientation assists in preventing air bubbles within the monomer from being trapped by this discontinuity in the lens-forming surface  22  of the front mold  20 . Bubbles are more likely to remain in the mold cavity  60  if, for example, the flat top is horizontally oriented. 
     Referring again to  FIG. 5 , the fill bag  80  is at least partially constructed of a deformable surface on which the operator directs a compressive force so that one wall of the bag  80  moves inwardly toward the opposed wall. When that compressive force is applied, the fluid monomer located within the interior is forced toward and out of the injection port  82  to enter the mold cavity  60  via the feed opening  70 . In constructing a system necessitating minimal capital investment, the illustrated embodiment is inexpensively designed and relies on the operator hand squeezing the bag  80  to fill the mold cavity  60 . 
     Other means of injecting monomer into the mold cavity  60  are contemplated. Examples of such systems using a deformable bag to fill the mold cavity  60 —particularly for more complex casting designs—is disclosed in U.S. patent application Ser. No. 10/095,130, filed on Mar. 11, 2002 and entitled “Method and Apparatus for Dispensing a Fluid”. Monomer fill systems similar to the design disclosed in U.S. Pat. No. 6,103,148 is another option. 
     Once monomer fills the mold cavity  60 , the bag  80  is separated from the mold and then the monomer is cured (as discussed in more detail below). 
     Mold Materials 
     Materials suitable for forming the molds of the invention include a variety of thermoplastic or substantially thermoplastic materials that can be injection molded. The materials are preferably optically transparent. Suitable amorphous thermoplastic materials include, but are not limited to, polycarbonate, acrylics, polystyrene, CAB (cellulose acetate butyrate), polyesters, and combinations thereof. In general it is also desirable that the thermoplastic material be selected such that it will not be attacked by coating and/or monomer material used to form the lens. In general higher molecular weight analogs are desirable because they are typically more resistant to coatings and monomers used to form the lenses. 
     Amorphous thermoplastics can provide the advantage that, unlike crystalline thermoplastics, they tend to maintain an optical-quality surface for long periods of time, and so have a long shelf life with proper storage. In contrast, crystalline thermoplastics such as polypropylene, undergo dimensional changes after they are injection molded. These dimensional changes occur due to the polymer&#39;s attempt to arrange itself in a more crystalline structure. The result of this rearrangement is that the plastic part can have an uneven, non-optical surface. In contrast, amorphous thermoplastics will typically retain the shape they took on during the injection molding process. Not all thermoplastics are either 100% crystalline or 100% amorphous, so the scope of this disclosure ranges from “substantially amorphous” to totally amorphous materials, meaning thermoplastics that contain mostly amorphous materials. 
     The present invention is directed, in part, to a disposable mold for creating an ophthalmic lens. the disposable mold can include a substantially amorphous thermoplastic material forming an optically precise surface. The mold can also include a coating in direct contact with the optically precise surface, the coating configured to be incorporated into an ophthalmic lens and further configured removable from the mold. Suitable substantially amorphous thermoplastic materials include acrylic, polycarbonate, polystyrene, polyester, polyamide, cellulose acetate butyrate, and combinations thereof. 
     It is generally desirable that the amorphous thermoplastic mold retain its dimensional stability and optical surface quality after formation of the mold. Also, in some implementations the amorphous thermoplastic material includes a mixture of an amorphous material and a crystalline material. The thermoplastic material will typically have a glass transition temperature above the curing temperature of lens casting material used to form a lens. 
     Depending upon the material used to form the lens itself, it is often desirable to have the thermoplastic material be substantially transparent to radiation between wavelengths of 250 and 600 nm, allowing various radiation-initiated curing processes to be used to make the lenses. 
     Typically the mold material does not contain a plasticizer, or contains very little plasticizer. One problem with plasticizers is that they can cause imperfections in the mold surface. Thus, any plasticizer that is present should be at low enough levels so that it does not alter the optical surface of the mold. In addition, it is desirable that any plasticizer does not cause premature release of the lens material or coating material and it does not inhibit the cure of the lens or the coating. Also, certain plasticizers can gradually bleed out of a mold material and onto the surface of the mold. This is problematic, because it can destroy the optical surface either by creating an uneven surface or by integrating itself with the lens-forming composition. Thus, any plasticizer should not alter the useable shelf life of the coated or uncoated molds. 
     Mold Coatings 
     In certain embodiments of the invention a coating is applied to the interior of the mold prior to forming the lens. In some embodiments the coating is applied to interior portions of the mold by dip coating, spin coating, spray coating, flow coating, electrostatic spray, roll coating, modified roll coating, print coating, or other coating method. The coating may then optionally also be subjected to a “precure” to partially cure the coating so that it will stay in place and not move during subsequent steps in the process. 
     In some embodiments the invention includes disposable molds comprising a substantially amorphous thermoplastic material forming an optically precise surface containing less than an operable quantity of a mold release agent or plasticizer where less than an operable quantity means that the component does not interfere with curing of the coating or lens monomer formulation, or compromise the optical surface of the mold or lens formed therefrom. Thus, the mold can be substantially free of external or internal plasticizers; said plasticizers defined as a material that is chemically different from the thermoplastic material. 
     The invention also includes disposable molds for forming an ophthalmic lens wherein the mold includes a substantially amorphous thermoplastic material forming an optically precise surface; and a coating in contact with the optically precise surface of the mold, the coating configured to be incorporated into an ophthalmic lens and removable from the mold. 
     The molds can be coated with any of a variety of coating formulations, provided that the coating does not chemically attack the mold. The coating formula can include, for example, acrylate functional materials capable of crosslinking, initiators or catalysts capable of initiating the reaction of acrylates, flow or leveling agents, defoamers, stabilizers, UV absorbers, antioxidants, dyes, and possibly solvents. Some solvents can be used in the coating formulation, as long as such formulations do not substantially attack the mold before the formulation has cured. Solvents that could be used would include alcohols, glycols ethers, etc. Solvents that would be less acceptable for use would include lower molecular weight ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclohexanone; acetates; aromatic solvents such as benzene, xylenes; low MW hydrocarbons such as hexane, etc. 
     Suitable coatings include those that provide a hardcoat for improved scratch-resistance, a tintable coat for the purpose of making sunglasses or other “fashion” tints, a UV coat to prevent certain wavelengths of UV light to pass through the lens, an AR (“anti-reflective”) coat to prevent glare, or any other type of ophthalmic coating. The coating should be selected so that it does not attack the mold material. Such coatings remain on the mold temporarily and are transferred to the finished lens during the lens curing step. Thus, the coating is applied to the mold with the intent that it becomes an integral part of the finished lens. 
     In general it is important that the coating not attack the interior of the mold and be readily releasable from the mold. Accordingly, coating formulations should not have enough solvating power to attack the mold. The coating preferentially has a more complete cure at the mold/coating interface than at the coating/air interface. 
     Lens Forming Formulations 
     The molds of the present invention are suitable for use with a variety of resin compositions to form finished optical lenses. In general, molds made in accordance with the invention are well suited to use of radiation initiated curing processes, such as by exposure to ultraviolet or visible light, but can also include thermally cured materials if the thermal cure temperature is below the glass transition temperature T g  of the mold. 
     Suitable lens forming compositions include materials having low cure temperatures, which cure quickly, including acrylates, methacrylates, and styrenes. In some implementations epoxies can be used. 
     It is generally desirable to have the lens forming formulation be inert or substantially inert to the mold itself. However, in certain circumstances the lens material is not inert to the mold material, in which case an intermediate coating material can be used to prevent degradation of the mold. Typically the coating is applied first to the interior of the mold, cured or partially cured, and then the primary lens forming formulation is added. 
     Any of a variety of photocleavable or thermal initiators can be used. The level of photo initiator or thermal initiator used is typically low (less than 5%) and would not have a significant impact on the chemical aggressiveness of the lens formulation on the mold. In general, lower temperature curing of the lens is preferred, accomplished with UV or visible light photo initiators, low initiation temperature thermal initiators or a combination of both. A variety of light sources can be used, including those with output in the UV-A range, UV-B range visible range, or combinations thereof. 
     Depending on the choice of thermoplastic materials used, there will be certain chemistries and/or process parameters that will allow the mold to be used satisfactorily. Based on the simple chemical notion that “like dissolves like,” each different type of thermoplastic material can be used without issue with certain ingredients typical of a coating formulation and/or lens formulation. In order to determine if a raw material (or group of raw materials in a formulation) will be chemically compatible with mold material, any number of tests can be employed: 
     One screening test for chemical compatibility involves a representative sample of the thermoplastic material to be placed in close contact with the chemical to be tested. This “close contact” can involve soaking the thermoplastic in the test solution, or the test solution can be allowed to sit on top of the thermoplastic material. The time and temperature during which the two materials are in contact are controlled variables in the test. After the test period is over, all excess test solution is removed from the thermoplastic material by simple wiping, and the thermoplastic is evaluated for any damage by measuring any change in physical appearance, any change in percent transmittance, any change in refractive index, any change in tensile strength, any change in flexibility, any change in weight or size, any change in surface smoothness, or any change in optical properties. 
     In certain embodiments of the invention, the formulation used to form the lenses and the material used to form the mold is selected based upon solubility properties of the mold material and the lens forming formulation. Although it is difficult to determine solubility of a solid material in a resin, the durablity of the mold can be used as an indication of solubility. Applicants have found that the lens forming formulation should be selected such that the resin does not significantly degrade optical properties of the mold surface upon exposure to the resin. In general it is desirable to have low solubility of the mold material in the lens forming formulation. 
     Any significant change in any of the above properties of the thermoplastic constitutes damage to the material, and the thermoplastic material cannot be used with that test solution. However, it is still quite possible that although a certain ingredient is known to attack a particular thermoplastic material, that ingredient can still be used in small amounts in solution, provided that the other components are compatible with the thermoplastic. Numerous examples of such scenarios are provided for in this patent. 
     Methods for Casting and Curing Lenses 
     The present invention is also directed to methods for casting lenses. For an initial step, the method of the present invention involves providing the ring  50  and front and rear molds  20 ,  40 . Although it is contemplated that the components be pre-connected together as a unit and provided to the operator, it is preferred that the ring  50  and front and rear molds  20 ,  40  are preferably combined or coupled together by the operator at the lens manufacturing location to form the mold cavity  60 . When the operator receives the prescription of a spectacle lens, he or she selects the front and rear molds  20 ,  40  that, together, form a mold cavity  60  having the dimensions of the desired lens. In the illustrated embodiment, the ring is a “one-size” or “universal” ring and used to manufacture all lenses, whether plus or minus and regardless of power. 
     To that end, the ring  50  and front and rear molds  20 ,  40  are movable between a stored position and a molding position. In the stored position, the components are separated from each other, in which molds having the same characteristics are stored together in designated areas or bins. In the molding position, the protrusion  46  of the rear mold  40  receives the edge  28  of the front mold  20  to form the mold cavity  60  after the operator retrieves the correct molds from the designated storage areas. 
     It is contemplated using computer or other system (not shown) to assist the operator in selecting the correct molds  20 ,  40  when preparing to cast a lens. As one example, the present invention contemplates that the operator enters the parameters of the lens to be formed (e.g., the prescription including add power) into a computer or the like. Algorithms in an associated computer program determine the appropriate front and rear molds  20 ,  40  to be used to form the desired lens and then provide an output indicating this information. As one optional variation, such a system may additionally illuminate a light or provide another indicator at the storage stations above the specific location where the appropriate molds  20 ,  40  are stored. The indicators assist the operator in locating the appropriate molds to reduce the chance of the operator inadvertently picking an incorrect mold to make the lens. Yet another option is to use a bar code or other tracking system (not shown) on the outer surfaces of the molds  20 ,  40  that the system scans to verify that the two proper molds are being used. 
     After the operator locates the front and rear molds  20 ,  40 , obtains a ring  50 , and is ready to join the components together, the output of the optional computer system may further assist the operator by indicating additional positioning and aligning information. As discussed above, in the illustrated embodiment the front and rear molds  20  are rotatably movable relative to each other so that the two molds  20 ,  40  are at one of a plurality of selected rotational orientations relative to each other. The computer may provide an output indicating the orientation of the two molds  20 ,  40  relative to each other when the lens-forming surfaces  22 ,  42  of the respective molds have asymmetric curvature. For the illustrated embodiment, the computer preferably indicates the appropriate location of the axis-positioning indicator  92  to be aligned on the axis marks  90 . 
     As to the positioning of the molds  20 ,  40  to obtain the correct center or edge thickness for the mold cavity  60 , this parameter is preferably considered in selecting the ring  50  and molds  20 ,  40 , as discussed above. The designated components are preferably manufactured so that when the operator combines or assembles the components together, the mold cavity  60  has the correct thickness without any additional actions. 
     However, one skilled in the art will appreciate that other means besides a computer system may be used to determine the correct mold to use with the present invention. Notably the present invention utilizing the computer system allows an operator with minimal training and understanding of the principles of lens casting to manufacture successfully lenses when a customer provides a prescription. 
     After the front and rear molds  20 ,  40  are joined with the ring  50  to form the mold cavity  60  of the desired dimensions, the operator connects the bag  80  or other source of monomer to the feed opening  70 . The operator then injects the monomer into the mold cavity  60 . 
     During filling, the monomer enters via the feed opening  70  while the vent opening  72  allows displaced air to exit the mold cavity  60  to ambient. The filling method used with the present invention minimizes the quantity of monomer wasted and decreases the chances of air bubbles being formed within the lens. If used, the bag  80  may contain a quantity of monomer that is sufficient to form only a single lens or, alternatively, for multiple castings. 
     Because monomer is a viscous fluid, it will inherently fill the mold cavity  60  at a controlled rate. By design, the fill rate may be further controlled by reducing the cross-sectional area of the feed opening  70  and/or the tip  84  of the bag  80 . Since the front and rear molds  20 ,  40  are formed of plastic, they can be clear or transparent so that the operator may visually observe the monomer entering and filling the mold cavity  60 . When the cavity  60  is filled with monomer so that the monomer reaches the vent opening  72  (and thus the top of the extender of the feed opening  70 ), the monomer source is removed from the ring  50 . If necessary, the feed opening  70  is plugged, which may simply involve spot curing the monomer at that location to plug it or using a covering that snaps into the feed opening  70 . The vent opening  72 , however, preferably remains in communication with ambient during curing. 
     The monomer within the mold cavity  60  is then cured to form the lens after ensuring that no bubbles are present. The lens material, depending on the formulation, can be cured with a variety of methods, including light, heat, or combinations thereof. If a free-radical mechanism is employed, then the lens can be cured via either UV light, visible light, or heat, depending on the initiator. It is also possible to cure the lens with a combination of these curing techniques. These curing methods can be used either simultaneously or sequentially. 
     Both curing techniques can be used with a variable rate of cure (i.e., ramp-up, progressive cure.) After the cure cycle is complete (typically from two to ten minutes) the lens is removed from the molds simply be removing the gasket, and lifting the molds away from the lens. 
     Methods of Making Lenses Using Plastic Molds 
     The present invention is also directed to methods of casting lenses using plastic molds, which may be used with the exemplary embodiment discussed immediately above or another design (i.e., a T-gasket design that uses plastic molds instead of glass molds). The method can include providing a substantially amorphous thermoplastic material injection molded to form a mold having an optically precise surface, plus providing a first curable composition suitable for forming an ophthalmic lens, said first curable composition being unreactive with the amorphous thermoplastic material used to form the mold. A second curable composition is also provided, this second curable composition being compatible with the amorphous thermoplastic material used to form the mold. The optically precise surface of the lens mold is coated with the second curable composition such that the second curable composition is in direct contact with the substantially amorphous thermoplastic material, and at least partially curing the second curable composition. Subsequently, a lens is formed within the lens mold by applying the first curable coating composition over the second curable composition, and curing the first curable coating composition. Thereafter, the cured lens is from the mold such that the cured second curable composition is removed with the lens and is secured to the cured first curable composition. 
     When selecting the specific type of material to form the molds, one skilled in the art will appreciate that to be useful in curing monomer, the selected plastic must transmit the curing radiation without melting, deforming, or stretching—at least until after the monomer is substantially cured or polymerized. Although thermal radiation is contemplated as a curing source and falls within the scope of the present invention, one skilled in the art will appreciate that the present invention may be better suited for photo curing. 
     For photo curing of liquid resins, the desirable plastics include acrylic and methacrylic materials, an example of which is polymethylmethacrylate (PMMA). Some embodiments of available light transmissive PMMA are the OP1 and OP4 products by Cyro Industries, UV-T and V8-25 by Rohm &amp; Haas, and CP-75 from ICI. Other exemplary types of radiation transmissive plastics that may be used with the present invention include aliphatic polyesters, amorphous polyamides, amorphous polyurethanes, amorphous polyolefins, amorphous polycarbonates, amorphous polyimides and co-polymers thereof. One skilled in the art will appreciate that these listed plastics are illustrative and the present invention is not limited to these examples. 
     Another factor that one skilled in the art considers in selecting the plastics to use is that they do not adversely interface or react with the material to be cured. If, for example, it is desired to use polymethylmethacrylate to form the molds based on its cost or physical properties, then compatible monomers include long chain or high molecular weight monomers or prepolymers that do not attack the mold should be used. Alternatively, the monomer desired to be used may be the primary consideration and the plastic forming the molds is chosen based on it being chemically resistant and non-reactive to that selected monomer. 
     Using plastic to form the molds provides potential benefits over casting systems currently used in the industry. One consideration is that the plastics may be injection molded. There is extensive use and experience in the industry of injection molding polymethylmethacrylate and acrylics using ceramic or metal molds. To that end, the molds may be formed, for example, by fabricating metal dies into which polymethylmethacrylate or other plastic is injection molded in an assembly process having a high throughput. Each of the molds, accordingly, will be formed to the same high tolerances to which the die is formed. Glass molds, in contrast, cannot be fabricated to such exacting standards, so the present invention can cast an ophthalmic lens that is formed to more rigorous criteria. One skilled in the art will further appreciate that the plastic components may be formed using other suitable high throughput methods used in the art for fabricating plastics, in contrast to glass molds that cannot feasibly be mass-produced to the requisite tolerances. 
     Another consideration with using plastic components is the economic comparison with conventional prior art systems using two glass molds and a gasket. Although glass molds may be repeatedly used up to one hundred times or more, expenses accumulate that are associated with each casting, such as washing and drying that must ensure that the lens-forming surface is not contaminated. In fact, cleaning processes for glass molds are typically laborious, time-consuming and inefficient, involving manual scraping and soaking in noxious solvents. Furthermore, the glass molds must be inspected after each use and cleaned to insure suitability for another lens-making cycle. Plus, many times the glass molds are inadvertently chipped and/or broken before their potential useful life is reached. An associated problem is the occurrence of lens yield loss resulting from unwitting reuse of damaged lens molds, in which the operator sometimes does not discover that a glass mold is damaged until after a casting process has been completed. 
     Yet another aspect of the present invention involves coating the lens-forming surfaces of the molds with an abrasion-resistant composition that is transferred to the lens when cured. More specifically, the lens-forming surfaces are preferably covered with a composition that transfers in situ to the optical surfaces of the cast lens as a protective coating on the final product. Without such a hard coating on the lens that prevents or resists abrasion, scratching, and marring, the optical quality of the cast spectacle lenses may more easily degrade from haze and poor image quality. 
     Another example of such an abrasion-resistant coating is disclosed in U.S. Pat. No. 5,049,321. This patent discloses that the coating composition consists substantially of reactants having at least triacrylate functionality, a photoinitiator, and a polymerization inhibitor reactive with oxygen. After applying such a coating composition in the form of an ultraviolet curable liquid to the mold, the coating is subjected to ultraviolet radiation in an oxygen-containing environment such that the coating composition is cured to a hard/abrasion-resistant state. Then, when casting and curing the ophthalmic lens, the monomer is permitted to harden and react with acrylate groups at the coating/lens interface so that the coated lens is removed from the mold with the abrasion-resistant coating adhering thereto as an integral part of the surface of the optical surfaces of the lens. Other similar techniques of forming an abrasion-resistant coating on a cast lens are disclosed in U.S. Pat. Nos. 4,338,269 and 4,758,448. 
     One skilled in the art will appreciate that, although not necessary, using such an abrasion-resistant coating on the lens-forming surfaces produces a final product that consumers may prefer and that also allows the operator to separate more easily the molds from the lens cast therebetween. To that end, the abrasion-resistant coating may be applied to the lens-forming surfaces of the molds using a process the same as or similar to that disclosed in U.S. patent application Ser. No. 10/075,637, filed on Feb. 12, 2002 and entitled “Methods of Applying a Coating to an Optical Surface”. Alternative treatment methods of the molds known in the art include spraying, dipping, brushing, flow coating, spin coating, and the like. 
     The preferred method involves curing using photo curing, although other curing methods are contemplated in conjunction with or alternatively to light. One primary advantage of photo curing, such as UV radiation, is that the plastic molds do not reach a temperature at which they may melt, deform, or stretch, which is more likely to occur with thermal radiation curing. UV curing methodologies are taught, for example, in U.S. Pat. Nos. 4,919,850; 5,524,419; 5,804,107; 5,981,618; 6,103,148; and 6,241,505. 
     After the monomer is cured to harden, then the operator removes the cured lens from within the mold cavity. It is contemplated that the plastic components of the present invention will have a one-use life. That is, the molds can be disposable so that there are no problems if the molds are chipped or broken during the removal of the lens from the mold cavity. In fact, breaking the molds may assist in separating the cured lens from the mold cavity  60 , as the molds are more brittle than the cured lens so the lens does not also break. One skilled in the art will also appreciate that treating the lens-forming surfaces with abrasion-resistant coatings, such as the compositions disclosed in U.S. patent application Ser. No. 10/712,714 and U.S. Pat. No. 5,049,321, will assist in separating the lens from the mold as well as providing the lens with a protective scratch-resistant barrier. One skilled in the art will further appreciate that the plastic molds of the present invention can be used for more than one casting before their useful life ends. 
     EXAMPLES 
     The invention will now be further understood by reference to the following examples. As used in these examples, SR 340 is the monofunctional monomer 2-phenoxyethylmethacrylate; SR 506 is isobornyl acrylate; SR 150 is ethoxylated bisphenol A dimethacrylate; Ebecryl 1039, which is a urethane monoacrylate; Ebecryl 810, which is a polyester tetraacrylate; CN 131 is a low viscosity aromatic monoacrylate oligomer; and SR 203 is a tetrahydrofurfuryl methacrylate monofuntional cyclic monomer. All numbers below are in parts. The lenses were cured between two acrylic molds. The cure time was 5 minutes (except for the 100% SR 203 formulation, which was cured for 30 minutes). The formulations were photocured. 
     Examples 1 to 3 
     Lens Formation Interaction 
     These examples show how diluting an aggressive formulation component with a non-aggressive component can modify the mold-formulation interaction. 
     Example 1 
     The molds for Example 1 were formed of uncoated acrylic. As can be seen from Table 1, the use of a mixture containing more of the less aggressive component (SR 150) than the aggressive component (SR 340) resulted in less lens damage. Lens damage means the lens was not optically acceptable. One type of observed lens damage is when a portion of the mold is stuck on the lens after de-molding. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 SR 150 
                 100 
                 90 
                 85 
                 80 
                 70 
                 50 
                 0 
               
               
                 SR 340 
                 0 
                 10 
                 15 
                 20 
                 30 
                 50 
                 100 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 Yes 
                 Yes 
               
               
                 Damage 
                   
                   
                   
                   
                 (minor) 
                 (Light) 
                 (Heavy) 
               
               
                   
               
            
           
         
       
     
     Example 2 
     The molds for Example 2 were formed of uncoated acrylic. As can be seen from Table 2, the use of a mixture containing more of the less aggressive component (SR 150) than the aggressive component (CN 131) had less lens damage. 
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 SR 150 
                 100 
                 90 
                 85 
                 80 
                 70 
                 50 
                 0 
               
               
                 CN 131 
                 0 
                 10 
                 15 
                 20 
                 30 
                 50 
                 100 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 Yes 
                 Yes 
               
               
                 Damage 
                   
                   
                   
                   
                 (Minor) 
                 (Light) 
                 (Heavy) 
               
               
                   
               
            
           
         
       
     
     Example 3 
     The molds for Example 3 were formed of uncoated acrylic. As can be seen from Table 3, the use of a mixture containing more of the less aggressive component (SR 150) than the aggressive component (SR 203) had less lens damage. 
     
       
         
           
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 SR 150 
                 100 
                 90 
                 85 
                 80 
                 70 
                 50 
                 0 
               
               
                 SR 203 
                 0 
                 10 
                 15 
                 20 
                 30 
                 50 
                 100 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 Yes 
                 Yes 
               
               
                 Damage 
                   
                   
                   
                   
                 (Minor) 
                 (Minor) 
                 (Heavy) 
               
               
                   
               
            
           
         
       
     
     Examples 4 to 6 
     Examples 4 to 6 below show the effect of temperature on curing various lens materials. As can be seen, increasing the cure temperature to 50° C. can result in a damaged lens, and sometimes to a milky lens. 
     Example 4 
     The molds for Example 4 were formed of uncoated acrylic. As can be seen from Table 4, the higher temperatures at which the lenses were cast resulted in more lens and/or mold damage and haze formation. 
     
       
         
           
               
               
             
               
                   
                 TABLE 4 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Temper- 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
               
               
                 ature 
                 temp. 
                   
                 temp. 
                   
                 temp. 
                   
               
               
                 SR 150 
                 100 
                 100 
                 80 
                 80 
                 50 
                 50 
               
               
                 SR 340 
                 0 
                 0 
                 20 
                 20 
                 50 
                 50 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No/No 
                 No/No 
                 No/No 
                 Yes/Yes 
                 No/No 
                 Yes/Yes 
               
               
                 Damage/Haze 
               
               
                   
               
            
           
         
       
     
     Example 5 
     The molds for Example 5 were formed of uncoated acrylic. As can be seen from Table 5, the higher temperatures at which the lenses were cast resulted in more lens and/or mold damage and haze formation. 
     
       
         
           
               
               
             
               
                   
                 TABLE 5 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Temper- 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
               
               
                 ature 
                 temp. 
                   
                 temp. 
                   
                 temp. 
                   
               
               
                 SR 150 
                 100 
                 100 
                 80 
                 80 
                 50 
                 50 
               
               
                 CN 131 
                 0 
                 0 
                 20 
                 20 
                 50 
                 50 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No/No 
                 No/No 
                 No/No 
                 Yes/No 
                 Yes/No 
                 Yes/Yes 
               
               
                 Damage/Haze 
               
               
                   
               
            
           
         
       
     
     Example 6 
     The molds for Example 6 were formed of uncoated acrylic. As can be seen from Table 6, the higher temperatures at which the lenses were cast resulted in more lens and/or mold damage and haze formation. 
     
       
         
           
               
               
             
               
                   
                 TABLE 6 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Temper- 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
                 Room 
                 50° C. 
               
               
                 ature 
                 temp. 
                   
                 temp. 
                   
                 temp. 
                   
               
               
                 SR 150 
                 100 
                 100 
                 80 
                 80 
                 50 
                 50 
               
               
                 SR 203 
                 0 
                 0 
                 20 
                 20 
                 50 
                 50 
               
               
                 Photo- 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 initiator 
               
               
                 Lens 
                 No/No 
                 No/No 
                 No/No 
                 Yes/Yes 
                 No/No 
                 Yes/Yes 
               
               
                 Damage/Haze 
               
               
                   
               
            
           
         
       
     
     Example 7 
     The molds for Example 7 were formed of acrylic. Example 7 shows lens damage comparing coated molds and uncoated molds. Table 7 exhibits the potential advantages of coating the molds prior to filling with formulation and subsequent curing. 
     
       
         
           
               
               
             
               
                   
                 TABLE 7 
               
             
            
               
                   
                   
               
               
                   
                 Formulation 
               
            
           
           
               
               
               
               
               
            
               
                   
                 1 
                 1 
                 2 
                 2 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Mold Coated 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 Temperature 
                 Room Temp. 
                 Room Temp. 
                 50° C. 
                 50° C. 
               
               
                 SR 150 
                 0 
                 0 
                 80 
                 80 
               
               
                 SR 340 
                 100 
                 100 
                 20 
                 20 
               
               
                 Photo-initiator 
                 0.35 
                 0.35 
                 0.35 
                 0.35 
               
               
                 Damage/Haze 
                 Yes/No 
                 No/No 
                 Yes/Yes 
                 No/No 
               
               
                   
               
            
           
         
       
     
     Examples 8 to 10 
     Examples 8 to 10 provide mold-formulation interaction data for molds made from a variety of polymers. The following information can be ascertained from the examples: First, different mold materials behave differently. In addition, coating the molds suitably can help prevent mold and lens formulation interaction, and minimizing the time the lens formulations are in contact with the molds prior to cure is an advantage. The lower the mold and lens formulation temperature is, prior to and during cure, the less likely mold-formulation interaction is to occur. Finally, under suitable conditions it is possible to cure and successfully separate molds and formulations without pre-coating the molds. [For tables 8, 9, and 10, only the test material is listed. The remainder of the formulation in these examples consists of SR-150 and photoinitiator(s). In Examples 8-10, “No” means there was no lens damage as defined in Example 1, “Yes” means lens damage was observed.] 
     Example 8 
     Example 8 shows temperature and time as factors in lens manufacture, using acrylic molds. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Material 
                 Ebecryl 1039 
                 SR 340 
                 CN 131 
                 Ebecryl 810 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 % Material 
                 Temp. 
                 Time 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                 10 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                 30 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
               
               
                 50 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 RT 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 0 
                 50° C. 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                 10 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 No 
                 No 
                 No 
               
               
                 30 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 50 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
               
            
           
         
       
     
     Example 9 
     Example 9 shows temperature and time as factors in lens manufacture, using polystyrene molds. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Material 
                 Ebecryl 1039 
                 SR 340 
                 CN 131 
                 Ebecryl 810 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 % Material 
                 Temp. 
                 Time 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 10 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 30 
                 RT 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 50 
                 RT 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 RT 
                 10 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 0 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 10 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 30 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 50 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 50° C. 
                 10 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
               
            
           
         
       
     
     Example 10 
     Example 10 shows temperature and time as factors in lens manufacture, using polycarbonate molds. 
     
       
         
           
               
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Material 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 % 
                   
                 Ebecryl 1039 
                 SR 340 
                 SR 203 
                 SR 506 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Material 
                 Temp. 
                 Time 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
                 Coated 
                 Uncoated 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                 10 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
                 No 
               
               
                 30 
                 RT 
                 10 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 No 
               
               
                   
                   
                 30 Min. 
                 No 
                 No 
                 No 
                 No 
                 No 
                 Yes 
                 No 
                 No 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 RT 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No* 
                 Yes* 
               
               
                 0 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 10 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 30 
                 50° C. 
                 10 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 60 Min. 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                 100 
                 50° C. 
                 10 Min. 
                 No* 
                 Yes* 
                 No 
                 Yes 
                 No 
                 Yes 
                 No 
                 Yes 
               
               
                   
                   
                 30 Min. 
                 No* 
                 Yes* 
                 No 
                 Yes 
                 No 
                 Yes 
                 No* 
                 Yes* 
               
               
                   
                   
                 60 Min. 
                 No* 
                 Yes* 
                 No 
                 Yes 
                 No 
                 Yes 
                 No* 
                 Yes* 
               
               
                   
               
               
                 *During the hold period attack on the uncoated side caused it to leak. The coated side exhibited no evidence of attack. 
               
            
           
         
       
     
     Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details should be regarded as limitations upon the scope of the invention except as and to the extent that they are included in the accompanying claims.