MXPA96001616A - Method and apparatus for applying a surge to agent surfaces mo - Google Patents

Abstract

A method and apparatus for employing a surfactant is provided to assist in the release of each of the mold components from a multi-part mold used in the molding of polymeric articles, for example, such as a contact lens. hydrophilic, at the end of the molding process for polymeric articles, this surfactant is applied in the form of a film or coating on surface portions of one of the mold components to facilitate uncoupling between the mold components during demolding, and the removal of excess polymeric molding material adhesively deposited on its surface.

Description

METHOD AND APPARATUS FOR APPLYING A TENSITIVE AGENT TO MOLD SURFACES CROSS REFERENCE TO THE RELATED APPLICATION This application is a continuation patent application in part series No. 0fi / 25ñ, 263, filed on June 1, 1994.

BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to a method for employing a surfactant that is provided for the purpose of aiding the release of each of the mold components from a multi-part mold used in the molding of polymeric articles; for example, such as hydrophilic contact lenses, upon completion of the molding process for polymeric articles. The method according to the invention also contemplates the application of the surfactant agent in the form of a film or coating on surface portions of one of the mold components in order to facilitate uncoupling between the mold components during the demolding, and the removal of polymeric molding material in excess adhesive deposited on the surfaces thereof; which, for example, may be in the form of externally configured rings of the respective mold cavities for the contact lenses, and which are formed through the displacement of the polymeric material from the mold cavity. In addition, according to another aspect of the invention, a novel and unique apparatus is provided which is adapted to effect the application of a coating or film containing a surfactant to surfaces of mold components for molding hydrophilic polymer articles, especially such as hydrophilic contact lenses or the like. Accordingly, any excess molding material encountered during contact lens molding, which is ejected from the mold cavities and as a result adhesively deposited in the ring configuration on the surface portions between the mold components. located externally around the mold cavities, it can be easily removed and cleaned under heat separation of the mold components in view of the presence of the surfactant coating or film. This also facilitates the essentially undamaged removal of the molded articles from the molding cavities during the separation of the components thereof at the end of the molding process for the articles. An extensive arrangement of methods is currently employed in this technology to carry out the manufacture of hydrophilic polymer articles, such as hydrophilic contact lenses, through the implementation of a considerable variety of procedures; among which are included casting or rotation, static casting molding, foaming, casting and foaming combinations, and frequently in particular, through the use of two-part molds. When using molds of two separable parts for the molding of hydrophilic contact lenses, at the end of the molding step, it is of great importance to be able to release the hydrophilic contact lenses from their surface coupling and adherence to the mold parts, or at least one of the mold halves, without damaging the contact lenses when separating the mold parts, which could make the lens unusable. Several concepts used to effect the release of hydrophilic contact lenses from mold surfaces, particularly from two-part molds that are intended to be physically separated, are through the use of mold part separation devices either by means of lightning laser or infrared heat, the use of external heat and / or the application of hot gas, air or hot stream. However, too often, the damage is maintained in the contact lenses during the removal of the same from the molds since the material of the mold parts can exhibit an adhesion and inhibit the easy release effecting the separation of the parts of the mold. mold. This potential damage usually makes the contact lens unusable to meet the necessary quality and / or inspection standards, may consist of breaks, tears or other surface defects formed in contact lenses, the most frequent being the so-called "piece of material" (PO) defects caused by excessive waste of polymer or particles produced during Molding that will permanently adhere to contact lenses after mold separation. Generally, such mold portions for hydrophilic contact lenses consist of a curvilinear (concave / convex) center part mold or front curve adapted to form, in cooperation with a matching base mold part curve, a two part mold for contact lenses. Hydrophilic contact lenses of the type considered herein are usually constituted of a hydrophilic polymer, preferably a polymer based on HEMA (hydroxyethyl methacrylate), although other suitable monomers may comprise hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate or , hydropyric acid acrylate and hydroxy trimethyl ethylene acrylate, among many other applicable materials. The components of the mold within which the hydrophilic polymer contact lenses are molded can consist of suitable paddles each including a plurality of cavities that receive mold parts having female and / or male base surfaces or curvilinear wall portions for the formation of curved contact lenses and a ring ring portion extending around them. The molds as described, for example in the molding technology, can be constituted of conventionally selected conventional plastic materials, whereby the hydrophilic polymer articles, i.e., the contact lenses, will possibly adhere to one of the parts of mold through the presence of mold part that have different properties or that are formed of different materials. The mold parts may consist of plastic materials such as polyethylene, polypropylene, polystyrene, polyvinyl chloride among other suitable plastic mold materials, as is well known in the art. To remove the molded hydrophilic contact lenses from the respective mold cavities, separation of the mold halves or portions is implemented, and the formed contact lenses can then be removed from the mold cavities. Due to the excess portions of the polymeric material of the hydrafied contact lenses which are removed from the mold cavities of the cooperating mold components, and which form ring-shaped elements of the polymer preferably based on HEMA from which the contact lenses surrounding the exteriors of the mold cavities are made, and exhibit tendencies to strongly adhere to the mold surfaces on which the rings are deposited. These rings make it difficult to separate the mold cavities, resulting in the breakage of the mold and damage to the lenses. In addition, the rings, or fragments of them, become an uncontrollable waste in automatic production lines, contaminating both the production line and the final lens package. In addition, the foregoing can also cause a perfectly "good" contact lens to be rejected after demolding due to the HEMA ring formed or a portion thereof remaining on the front curve of the mold. This results in non-economic production conditions encountered during the manufacture of said contact lenses. 2. DISCUSSION OF THE PREVIOUS TECHNIQUE In order to implement the mass production and high speed molding of such hydrophilic contact lenses, two-part molds incorporating mold structures supported by vanes have been developed; for example, as described in the patent of E.U.A. No. 4,640,4A9 to Larsen, and wherein methods for forming shaped polymeric hydrogel articles, such as hydrophilic contact lenses, are also seen in the disclosures of US Patents. Nos. 4,660,336 and 5,039,459 to Larsen et al., Wherein the last two patents mentioned are assigned to the joint assignee of the present application and the descriptions of which are incorporated herein by reference. The release of the hydrophilic contact lenses from the adhering mold surfaces subsequent to the termination of the contact lens molding process can be facilitated or improved, as set forth in the description of the US patent. 5,264,161 to Druskis and others. In that case, the surfactants are introduced in solution into a hydration bath used in the molding cavities to mold the hydrophilic polymeric structures or contact lenses. The surfactant which is dispersed in the hydration bath in concentrations not exceeding 10% by weight, helps to facilitate the release of the lenses from adherent contiguous mold surfaces to be separated, the function of said surfactant is to reduce the tension properties on the surface of water or liquids, and thus reduce the level of adhesion between the components consisting, on the one hand, of contact lenses and, on the other hand, the mold surfaces that become adherent during molding. Numerous types of surfactants are disclosed in this patent application, particularly such as polymeric surfactants which include polyoxyethylene sorbitan monoleates, and which are especially suitable for releasing in an undamaged state any hydrophilic polymer articles from adherent mold surfaces which They are made of plastic materials. However, the use of surfactants in suspension to in a liquid hydration bath does not provide the desired control with respect to the release of the hydrophilic polymer articles or contact lenses from the mold surfaces prior to hydration in the bath and, in particular, does not readily offer easy removal of HEMA-based rings of the molding material formed in adherence to the mold surfaces that extend around the mold cavities, or easier separation between the mold component, so that the scale of damage encountered by the lens Contact during mold separation and mold removal is still unacceptably high and is not easily controllable to a degree that offers a satisfactory economical manufacturing environment.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, to improve the ability of such hydrophilic polymeric articles, especially hydrophilic polymer contact lenses, to be inherently releasable in an undamaged state of the mold cavities of mold structures where they are molded, the present invention contemplates the provision of a stamping station in a mold filling and forming machine for the formation of hydrophilic polymer contact lenses which are ordinarily constituted of a HEMA-based plastic material, wherein a plurality of stamping heads each include at least one a pattern for applying a thin layer or film of a polymeric surfactant; in this case, a polyethylene oxide monooleate sorbitan, commercially sold under the tradename "Tween 80", is preferably applied to the surface regions extending around the front curve of a mold part for the formation of contact lenses. This layer of surfactant, in essence, aids in the separation of a mold part defining a base curve adapted to cooperate coincidentally with a second mold part by defining the front curve for molding a contact lens, and in removing the excess molding material forming a HEMA-based ring that extends externally from the mold cavity for each contact lens of any potential adhesion to the surface of the mold part coated with surfactant during the demolding of the lens. According to the invention, the novel stamping station which provides for the application of a thin layer of the polymeric surfactant to the surface portions extending around the front curve of the mold part, such as a flange surface, contemplates the positioning of at least one mold blade or a pair of mold blades containing the front curves of a two-part mold (which are adapted to subsequently match the mold parts to mold the base curves of the contact lens) directly below a printing head consisting of a plurality of stamps each of which is adapted to couple respectively one of the surfaces or flange portions that extend around the front curves located on the mold pallet or pallets. A pad arrangement comprising a reservoir of the surfactant, for example, a polymeric surfactant, such as Tween 60, includes a plurality of discrete bearings adapted to move below the stamping head and which can remain there while the stamping the print head is moved down to contact with each other associated with the pad, and then retracted upward to allow the pad to move under the print head. The previous contact between the stamps and the printing head and the pad impregnated with surfactant aligned therewith disposed in the surfactant reservoir as a result causes each stamping to be wetted with the surfactant; in effect, the Tween 60 surfactant. Next, the print head moves downward towards the mold pallet or pallets to allow the stamps to be brought into contact each, respectively, with a surface aligned therewith or flange extending around a respective front curve placed on the mold blade, thus depositing a very thin layer or film of the controlled thickness surfactant on the surface around each respective front curve. The print head with the stamps is then retracted upwards and the machine is sequenced to the next mold vane or pair of front curve vanes of a two-part contact lens mold while concurrently advancing the front curves coated with surfactant Presented on its pallet or mold pallets to a machine station where the rear curve assembly on the front curve is implemented. With respect to a specific aspect of the invention, the discrete bearings to allow the stamps to be wetted with the surfactant include an upwardly open reservoir that extends substantially across the entire width of the collective stamps, and thus each of the individual or discrete bearings are adapted to at least partially immerse themselves in the surfactant in the reservoir to absorb the surfactant and allow the wick to move up through each of the bearings. A cover plate sealably covers the open area upstream of the container and has a plurality of openings formed therein in proportion to the number of bearings and associated stamps adapted for contacting the latter, to form a seal cover structure that prevents spillage of the surfactant from the tank. This is done since a seal is interposed between the perimeter of the reservoir and the lower surface of the cover plate, and the openings in the cover plate are in contact with the circumferential edges of each of the bearings along their lengths. upper surfaces. In order to be able to make a visual inspection of the deposit in order to know the level or quantity of surfactants contained therein, portions of the surface portion of the cover plate, the last generally constructed of a metallic material, can be constructed from of a transparent material, preferably such as Lexan (registered trademark). The application of a uniform thin layer or film of the surfactant to the various flange surfaces extending around each frontal curve with which the molding cavity has previously been filled with the HEMA molding material for the contact lens and then coupled subsequently and coincidentally by a part of the associated base curve mold after applying the surfactant, and wherein the base surfaces are deposited and adhered to the HEMA-based rings of excess material of the molding material for each One of the contact lenses is facilitated since subsequently the molding, each contact lens can be removed from the respective mold cavity thereof during the separation of the mold parts. The layer of surfactant that is applied or stamped onto the flange surface of the front curve may, preferably, but not necessarily, be within the range of about 0.05 to 0.50 mg of the surfactant for each frontal curve.

This separation of the mold parts, in effect, between the front curves and the base curves, is made easier due to the presence of a layer of surfactant between the coupled circumferential edge surfaces of the front curve and mold parts. of respective base curve. In addition, the surfactant on the flange or surface portion of the front curve mold portion to which the HEMA-based ring adheres of excess contact lens molding material expelled from the mold cavity, reduces the degree of adhesion and allows easy removal of the HEMA-based ring from each respective surface around the front curve, which during demolding results in a removal rate better than 95 of the HEMA ring without encountering any damage the contact lens. According to another advantageous aspect of the invention, the stamping head provides an elastically mounted multiple stamping structure which allows each stamping to "float" or be interchangeable to some degree independently of the displacement of the other stamped in view of a deviated assembly construction. by spring for each print. This, in effect, will ensure that an even amount of pressure is applied to the surfaces or flanges that extend around each front curve supported on the mold blade upon contacting a respective stamp having a surface wetted with surfactant previously. imparted thereto by the pad, to cause a uniformly thick film or layer of an equal amount of surfactant to be applied around each of the respective front curves. As stated above, according to a specific aspect of the invention as it is contained in the reservoir in a discretely separated predetermined position, each pad for applying the surfactant to an associated stamping of the stamping head can be used a material structure for a substantially porous pad, for example, a polyethylene pad, each pad being preferably, but not necessarily, being an essentially cylindrical member of a surfactant absorbing material which is intended to absorb surfactant from the reservoir and wick it towards the upper part of the respective pad when the latter is brought into contact by the stamps displaced downwards during the application or wetting with surfactant. A nylon filter, for example, with a size of maya within the scale of approximately 0.50 to 2.0 μ, and preferably of a mesh size of 1.2 μ is supported on the upper surface of each of the porous bearings, and acts as a measuring device to allow only a very small amount of the surfactant to pass therefrom through the nylon membrane filter towards the contact surfaces on the stamps of the printhead to form a layer of thin surfactant or surface moistened on it. This allows a highly accurate control to be exercised over the amount of surfactant that stops through the nylon filter to the prints and then upon removal of the pad, which is subsequently deposited by the prints on the surfaces or tabs that extend around the frontal curves that are placed on the mold pallet. Compared to the prior art, such as is presented by US Patent No. 5,264,161 to Druskis et al., Which only describes the use of surfactants that are suspended in a bath solution to be improved upon the release of articles of molded polymers of molds during separation, the present invention provides improved control over the amounts of surfactant being, in a novel form, distributed on and deposited on the applicable surface areas around the front curve mold part, thus allowing the removal of HEMA-based rings from the adherent molding material deposited around the frontal curves with only a minimal danger of damage the lenses, thus also making the whole procedure and apparatus highly cost-effective and economical in the manufacture of contact lenses of uniformly high quality. Accordingly, it is an object of the present invention to provide an arrangement for depositing controlled amounts of a surfactant on mold surfaces to facilitate the separation of the mold parts such as between the frothal curves and the base curves, allowing the removal of HEMA-based rings of excess molding material that adheres to the mold surfaces around the frontal curves, and essentially eliminate contamination of the production line and packaging at the end of the lens molding process. Another object of the present invention lies in the provision of a method for depositing thin films of surfactants on surfaces of mold parts to assist separation during the demolding of the mold parts, such as between the front curves and the curves of base used for the molding of contact lenses, allow the removal of HEMA-based rings of excess molding material that adheres to the mold surfaces around the frontal curves, and facilitates an essentially harmless release of the lenses from molded contact, using the arrangement described here.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to the following detailed description of an illustrative embodiment of a stamping arrangement used for the application of a polymeric surfactant to surface portions extending around the front curves of a mold structure for molded polymeric articles, particularly such as hydrophilic polymer contact lenses, facilitating the separation of the mold parts and the removal of any HEMA-based rings of molding material adhered thereto, taken together with the accompanying drawings, in which: Figure 1 , illustrates a top plan view of a typical mold vane of a two part mold to selectively support on it the rear or front curves employed for the molding of hydrophilic polymer contact lenses; Figure 2 illustrates a perspective view of a front curve frame assembly for the molding of contact lenses; Figure 3 uses a generally diagrammatic view, in section through a front curve arrangement and base curve assembled to mold contact lenses of hydrophilic polymer; Figure 4 diagrammatically illustrates a top plan view of a stamping section for the application of a surfactant to prints on a printhead and then for the deposition of a film or amount of the surfactant on portions of surface on the front curves of the mold parts placed on the contact lens molding blades; Figure 5 illustrates a sectional elevation view of the stamping station and an apparatus for selectively moving a stamping pad arrangement and molding paddles under the stamping head, taken along line 5-5 in Figure 4; Figure 6 illustrates a top plan view of the surfactant reservoir containing the pads of the stamping-pad arrangement; Figure 7 illustrates a sectional view taken along line 7-7 in Figure 6; Figure 6 illustrates, on an enlarged scale, a fragmentary detail of the deposit taken along the line β-6 in Figure 6; and Figure 9 illustrates, diagrammatically in general, an alternative embodiment of a pattern for applying the surfactant to the lens mold.

DETAILED DESCRIPTION Referring now more in detail to Figures 1 to 3 of the drawings, there is illustrated a mold frame or vane 10 of a suitable rigid material having depressions 16, which are adapted to mount front curve tabs 16 for molding, in cooperation with suitable base curves 19 each one forming together with them a two-part mold, in this case, a plurality of eight hydrophilic polymer contact lenses (not shown). As is well known in the art and as mentioned above, the material used for hydrophilic contact lenses may be constituted of a material based on HEMA (hydroxyethyl methacrylate) or an equivalent material. As shown in Figure 2, another embodiment or modification of a mold or vane frame 14 comprises individual concave mold units 12 forming injection points for the molding material for the plurality of contact lenses to be molded, and is adapted to match convex mold units of a two-part mold. The frame structure of two-part mold front mold curves are somewhat different than those contemplated in Figures 1 and 3, although the surfactant can be applied in the same manner, as described below; and other variations thereof are also easily conducted by themselves for use with the apparatus and method of the invention. Each concave mold unit 12 defines a front curve 16 for the content of a monomer material for the subsequent molding of a contact lens, as shown in Figure 3. Extending around the front curve is an integral flange 18a, joined to the front curve by means of an annular lip 18b extending around the mold cavity that is filled with molding material for lenses based on HEMA. To provide the complete two-part mold, a second mold part comprising a base curve 19 is subsequently adapted to superimpose coincidently on the front curve 18, after which the latter is supplied with a molding number, to form a cavity of molding 20 to form a contact lens therewith, with the base curve 19 peripherally being seated on the annular lip 18b. The base curve 19 includes an annular flange 19a extending radially outwardly, and when the parts 18, 19 are assembled, they form an annular recess with the flange 18a, between which excess HEMA-based molding material is received. ejected from the molding cavity 20 to form a HEMA ring that adheres to the surfaces of adjacent flanges. Generally, the mold parts 18 and 19 are constituted of a suitable plastic material, such as polyolefin including polyethylene, polypropylene, polystyrene, low, medium and high density, or other plastics that are adapted for this purpose; that is, the molding of contact lenses of hydrophilic polymer. Preferably, the mold part 19 is thinner and more flexible than the mold part 18. The specifications of such mold constructions, including the front curves and base curves for molding contact lenses, are known in the art, and reference is made to the US party Do not. 4,640,489 to Larsen, and is not discussed in more specific detail herein except as applicable to the invention. Referring now more in detail to the mode of a printing station as shown in FIGS. 4 to 8, and particularly in the representation of FIGS. 4 and 5, a printing station 30 is illustrated for applying a film or thin layer of a surfactant of the type described hereinafter, to the flange surface 18a of each respective front curve which is located in each depression 12, 16, respectively, of a pair of contiguous end-to-end mold vanes 10, as shown in FIG. Figure 1, or mold vanes 14 as shown in Figure 2. Of course, other types of mold vanes easily lead to the invention, and the mold vane patterns are considered as representative only by way of example . Care must be taken to avoid applying surfactant to the same lip 18b around the mold cavity, since touching the lip with surfactant can cause a defect in the lens to be molded. The application of the surfactant layer or film to the surface 18a of the front curves 18 on the mold blade 10 is intended to assist the separation therefrom of the base curves 19 subsequently applied during the demolding and to remove the rings based on HEMA which are mainly adherent to the flange surface 18 between the annular mold part flanges 18a, 19a in a demolding station subsequent to the conclusion of the lens molding process, to reduce potential damage to contact lenses which are being released from the mold cavities 20. As illustrated in Figures 4 and 5, the stamping station 30 includes a frame structure 32 having a support member or base 34 on which a plurality of columns are placed. guide straight 36 dependent down separately. These fixed guide columns 36 have sliding members 38 vertically slidable therein to support components for a print head unit 40 to move vertically along the guide columns. The print head unit 40 is mounted to allow reciprocal vertical movement of the prints, as described below, near the upper end of the columns 36 through the guide bush intermediary 42 and suitable sliding members 38, and where vertical displacement is implemented through suitable actuator elements or drive units, such as hydraulic or pneumatic actuators, which are not described in greater detail herein, and which, if desired, can be operated from one unit of control and adequate sensor (not shown). The printhead unit 40 includes mounted thereon a plurality of stamps 50, each adapted to be moved in a reciprocal vertical movement in a coordinated fashion together with the retainer plate member 52 mounted on the printhead unit 50, wherein the number of prints 50 is correlated with the number of front curves 18 located in the mold depressions 12, 16 formed in the respective mold vane 10 or mold frame 14. Each stamp 50 consists of a rubber or composition of about of urethane and 10% silicone in at least their portions that are adapted to contact the frontal curves on the mold vane 10 or 14. Mounted on the main frame of the apparatus to slide horizontally towards and away from the position below of the printing head unit 40 is a stamping pad arrangement 60, which is attached to a frame structure 6 2 at its opposite ends through the intermediary of the appropriate fastener members, and thus the entire frame structure 62, including the cushion arrangement of this pad 60, can be moved selectively towards and away from the position below the printing head unit 40 through the activation of a pneumatic cylinder 64 and piston device 66 attached thereto at one of its ends. In this case, the apparatus of the printing station 30 is of a width that can adapt two of the mold vanes or frames 10 or 14 in an end-to-end contacting relationship, to simultaneously adapt 16 parts of mold curve, as it is clearly indicated in figure 5 of the drawings, and the stamped pad arrangement 60 having an equal length and width in a plan view, as shown in figures 4 and 5. In the present case, in a modification of the apparatus illustrated in the main application, series number 08 / 258,263, instead of having a continuous embossing pad which is impregnated with the surfactant, the embossing pad arrangement 60 described herein consists of a reservoir 70 in the form of a structure of type upwardly open tundish, possibly containing a surfactant supply of up to 6 weeks, wherein a plurality of stamp bearings 72 are fixedly mounted, each generally with a circular cross-section or cylindrical shape, reference is made specifically to figures 6 to 6 of the drawings showing the detailed structure of the stamping pad arrangement 60. The reservoir 70 is constituted basically of a metallic material, such as, for example, stainless steel, having a rectangular configuration, mounted by means of fasteners 74 suitable to the actuating frame structure 62, which, in turn, is connected to the pneumatic cylinder 64 and, in a rectangular depressed portion 76 thereof includes a plurality of the generally cylindrical stamping bearings 72 mounted or supported on erect pins 7 &; . The reservoir 70 is covered by a single generally rectangular flat plate member 80, which may also be constituted of a suitable material such as stainless steel having a peripheral sealing member 82, such as a 0-shaped ring, positioned to extend between the upper perimeter of the reservoir, which may have a suitable slot 84 formed therein to receive the 0-shaped ring or sealing member 82, and the lower surface of the plate member 80 whereby the plate member 80 is subject to reservoir 70 through fasteners & amp; suitable, such as screws or the like. Openings 90 are formed in the plate member 80, positioned to be aligned and matched in number with each of the cover pads 62, and sized to contact the upper circumferential surfaces of the latter, as shown in Figure 8, and thus make a complete sealing arrangement for the surfactant contained in the reservoir 70. To provide visual inspection capability that there is an adequate supply of surfactant in the reservoir 70 capable of being absorbed by the punching pads 72, so less one or two surface portions 94 of metal plate member 80 can be carried and suitable plates 96 of a transparent plastic material, such as Lexan (registered trademark), are fixedly placed in the cutting areas. The top surface of each embossing pad 72 is covered by a filter 100, preferably nylon, having a mesh size in the scale of approximately 0.5 to 2.0 microns to act as a measuring device and allow only a relatively small amount of surfactant passes therethrough as the surfactant is wicking from the embossing pad 72 towards the top thereof, whereby the pads are contacted by the bottom ends of the prints 50 of the printhead unit 40, as described below. The interchangeable embossing pad and the reservoir structure 70, 72 through its horizontally displaceable nature, as shown in Figure 4 of the drawings, are adapted to move between the upright columns 36 and the sliding members 38 toward a position below the prints 50 or moves out away from them when not required. The stamping pad and reservoir 60, 70, prior arrangement and its actuator structure 64, 66 are located at an elevation or height above a mold vane rail, (not shown in detail) along which the pairs of mold vanes 10 or 14 are adapted to be sequentially advanced to a position below the printing head unit 40, as shown in Figure 5, in order to allow each of the patterns 50 to apply a thin film or coating of surfactant to the respective surface 18a, 18b of the front curves 18 located on the pallets before being transported along the lens manufacturing system together with the formation of. the contact lenses.

OPERATION OF THE APPLIANCE To facilitate the deposition of a film or thin layer of surfactant on the flange surface 18a of the front curves 18 on the mold blade 10 or frame 14 which has been placed below the print head unit 40, the The stamping head 40 is held in a fully elevated position on the sliding members 36. This is implemented by means of a suitable lifting cylinder arrangement (not shown) which acts on the sliding members 38 so that they move vertically within the columns of guide 36. The degree of vertical movement can be controlled by an appropriate control and sensor arrangement (not shown). Each stamping pad 72 in its reservoir 70 is interposed in a spaced relationship between a molding blade 10 or 14 and the lower ends of the stamping 50 on the stamping head unit 40, said components being vertically aligned therebetween in a separate relationship . This interposition of the embossing pads 72 is carried out by changing the frame structure 72 through the operation of the cylindrical piston device 64, 66 to locate the reservoir 70 below the embossments 50. Next, the embossing head unit 40 is actuated to cause the stamps 50 to be displaced downward towards a predetermined contact with the upper surface of a membrane filter 100 on an associated embossing pad 72, whereby a certain amount of the surfactant is expelled upwards through the nylon filter 100 and deposited on the bottom downward facing surface of each stamp 50, forming a thin layer or coating of the surfactant thereon. The surfactant contained in the tank 70 with which each pad 72 is impregnated, can be a solution with almost 100% concentrated strength of surfactant dispersed therein to allow the formation of a layer on the contact surfaces of the prints 50. Preferably, the surfactant is comprised of Tween 80 (registered trademark), ie, a Polysorvate 80. This is basically polyethylene glycerol sorbitan oxide or its equivalent, and consists of a sorbitol oleate ester and its copolymer anhydrides imitated with approximately 20 moles of ethylene oxide for each sorbitol and sorbitol anhydride templates; generally of the formula: The sum of w, x, y, z is 20; R is (C17Haa> C00) 3 To ensure that a very thin uniform layer or film of surfactant is deposited on the surface 18a of each of the front cups 18 that are located on the mold blade 10 or 14, each stamp 50 is individually and elastically imparted to the action of a suitable derailleur spring 104, preferably such as a coil spring that encompasses part of a stamping bar 106 supporting the stamping 50 at its lower end, thus ensuring that despite the tolerances of After the manufacture, a uniform pressure will subsequently be exerted by the stamps 50 provided by surfactants contracted to the contact surfaces 18a, 18b on the front curves 18 which are located on the mold vanes. Once the surfactant has been wicking through each stamping pad 72, ejected through the respective nylon filter 100 and deposited on the inner surface of each stamping 50, the stamping head unit 40 and the stamping 50 are displaced upwards, and the stamping pad arrangement 60 with its reservoir 70 moves horizontally by means of piston-cylinder device 64, 66 outside the stamping station 30 from its position between the guide columns 36, releasing thus the space between the patterns 50 and the front curves 18 aligned therewith on the mold vane 10 or 14. Next, the stamping 50 and the printing head unit 40 are again changed down along the vertical guide columns 36 by means of sliders 38 until the stamps 50 contact their lower end surfaces hucedecida with surfactants with the surfaces 18a, 18b on the front curves 18, thus depositing a thin film layer of the surfactant thereon, said layer having a uniform thickness on each front curve surface 18a, 18b due to the elastic deviating forces that are exerted by each of the springs 110 acting on the respective patterns 50. Subsequently, the stamping of the stamping head unit 40 again moves vertically upwards and a subsequent group of molding palettes 10 or frames 14 mounted front curves 18 advance towards the stamping station of the apparatus, while the mold pallet 10 or preceding frame 14 having the front curve surface thereon already treated with the surfactant is advanced outside the stamping station to match the base curves 19, as is known in the art. The procedure can then be repeated with the front curves 18 subsequently introduced on the mold vanes 10 or frames 14 in the same continuous shape. The above structure allows the deposition of a thin or uniform layer or film of the surfactant on the flange surface 18a specific to the front curves 18 to allow a subsequent easier separation of the base curves 19 thereof and the removal of the material HEMA-based ring that emerges during the molding of the hydrophilic polymer contact lenses, at the end of the molding sequence, and in the absence of encountering damage in the molded contact lenses that are released from the separated mold parts. Although in the embodiment described above in the apparatus, each rubber stamp 50 is shown as a concave element attached to its arrow element or bar 106 and driving the construction by means of a screw member 112 having specific reference to FIG. of the drawings; according to the alternative embodiment, as shown in figure 9 of the drawings, instead of being fastened by means of a screw element, each rubber stamp 120 may comprise an annular ring, with an enlarged annular flange portion or wedge type 122 adapted to be forced into a similarly shaped complementary groove structure 124 formed at the end of its support bar 126, thereby engaging in a rubber-stamped manner while eliminating the need for some screw member, the last of which can be easily loosened or dropped during continuous and repetitive operation of the apparatus. This pressure-fixed coupling of the elastic rubber stamp 120 by its flange 122 in the slot 124 ensures its firm coupling while removing a clamping component that can be loosened and simplifies its structure. Since what is considered to be the preferred embodiments of the invention has been shown and described, it will be understood, of course, that various modifications and changes in form or detail can be made without departing from the spirit of the invention. Therefore, it is intended that the invention not be limited to the exact form and details shown and described herein, or anything other than everything encompassed by the invention herein as claimed below.

Claims (1)

1. NOVELTY OF THE INVENTION CLAIMS 1. An apparatus for applying a surfactant to at least one surface of a mold part of a two-part mold having said first mold part engageable with a second mold part operative for the molding of polymer articles, wherein said The surfactant agent helps in the release between said first and second mold parts and allows the removal of excess adherent polymer molding material to at least one surface of said first mold part, said apparatus being characterized in that it comprises: a) means of support mounting at least a first mold part being movable to a predetermined location in said apparatus; b) Applicator means including at least one surfactant applicator that is disposed in a spaced apart relationship above the support means, at least said surfactant applicator can be placed in vertical alignment with said at least one first mold part; c) means for mounting an upwardly open reservoir containing a surfactant to be interposed between the applicator means and the support means for said first mold part, at least one pad member disposed in said reservoir for absorb the surfactant from the tank; d) actuator means for imparting a vertical downward displacement to said applicator means for causing at least one surfactant applicator to contact a pad member and assume a quantity of said surfactant, said actuator means then imparting a vertical upward displacement to said applicator means; and e) means for displacing said reservoir mounting means from their interposition in said apparatus between the applicator means and said at least first mold part, said actuator means for the applicator means moving the applicator means downwards to such an extent that portions Surface moistened with surfactant of said surfactant applicator are contacted with at least one surface of the first mold part to impart a coating of said surfactant thereto. 2.- An apparatus in accordance with the claim 1, further characterized in that a cover member is fixedly positioned on said tank at least one opening is formed in said cover member that is in alignment with at least one pad member to allow a surfactant applicator to be placed on contact with at least one pad member. 3.- An apparatus in accordance with the claim 2, further characterized in that said pad member is brought into sealed contact against a lower surface of the cover member adjacent to the circumference of at least one opening. 4. An apparatus according to claim 3, further characterized in that the seal means extends around said reservoir and a lower surface of the cover member to prevent the surfactant from leaking from the reservoir during the operation of the apparatus. 5. An apparatus according to claim 4, further characterized in that the seal means is placed in a groove formed in the lower surface of said cover member. 6. An apparatus according to claim 4, further characterized in that the seal means comprises a ring seal in the form of 0. 7. An apparatus in accordance with the claim 2, further characterized in that said cover member comprises a flat plate having at least a portion of transparent surface to be able to see the contents of said tank. 8. An apparatus according to claim 7, further characterized in that said transparent surface portion is constituted of a rigid transparent plastic material. 9. An apparatus in accordance with the claim 2, further characterized in that a plurality of said first mold parts is mounted in a predetermined spaced relation on said support means, each in vertical alignment with respect to a surfactant applicator of a plurality of said applicators, a plurality of members of pad being discretely located on said pad each in alignment with respect to one of the surfactant applicators, and a plurality of said openings forming in the cover member each in alignment with respect to one of the pad members. 10. An apparatus in accordance with the claim I, further characterized in that the applicator means comprises stamping means and said at least one surfactant applicator comprises a stamping. 11. An apparatus in accordance with the claim 10, further characterized in that said actuator means elevates said embossing means upward to the initial position thereof subsequent to imparting the layer of said surfactant to at least one surface of said first mold part; and operation buildings displace said support means for a first mold part and successively transport the mold support means by mounting at least another first mold part at said location in said apparatus. 12.- An apparatus in accordance with the claim II, further characterized in that the means for mounting at least one pad member comprises operating means for alternatingly placing at least one pad member below the stamping means and removing a pad member from said pad location in the apparatus for allowing at least one pattern to advance downward to contact at least one surface of at least one first mold part. 13. An apparatus according to claim 1, further characterized in that at least one pad member comprises a porous medium absorbing a solution in said tank containing the surfactant. 14. An apparatus in accordance with the claim 1, further characterized in that the upper surface of at least one pad member facing at least one surfactant-applying means is covered by a membrane filter having a mesh size with openings within the range of about 0.5 to 2.0 microns. 15. An apparatus according to claim 14, further characterized in that said membrane filter is a nylon filter that controls the amount of surfactant expelled upwards through said filter that responds to contact by said at least one applicator. of surfactant to deposit a predetermined amount of surfactant on the contact surface portions of at least one surfactant applicator. 16. An apparatus according to claim 1, further characterized in that at least in the surface portions of said surfactant applicator that is in contact with at least one pad member operatively associated with it to assume A surfactant is comprised of rubber or a compound that approximately comprises 90% urethane and 10% silicone. 17. An apparatus according to claim 1, further characterized in that a plurality of first mold parts is mounted on said support means, each first mold part comprising a front curve for molding a hydrophilic polymer contact lens and a surrounding flange portion, each mold means being operatively aligned with one of the plurality of the surfactant applicator whereby the contact between said front curve and an associated surfactant applicator transfers a thin film of said surfactant to a facing surface on said flange portion around the front curve of the surfactant applicator so that in a subsequent demolding operation facilitate the separation of a second mold part comprising a base curve for said lens and a ring of excess material of molding adhesively deposited on the surfaces of said portion flange around the front curve. 18. An apparatus in accordance with the claim 17, further characterized in that the support means for said first mold parts comprise at least one mold blade. 19. An apparatus according to claim 17, further characterized in that the spring means elastically mount each surfactant applicator on said applicator means so that each surfactant applicator moves in a floating manner relative to each other upon contacting. with the respective front curve so that a uniform contact is applied to each frontal curve and a uniform layer of said surfactant is imparted to each frontal curve. 20. An apparatus according to claim 1, further characterized in that at least one surfactant applicator comprises an annular member mounted on an end surface of said applicator means adapted to face towards at least one pad member and surface on said at least one first mold part. 21. An apparatus according to claim 20, further characterized in that said end surface comprises an annular groove for receiving said surfactant surfactant applicator securely. 22. An apparatus according to claim 1, further characterized in that the surfactant comprises a sorbitan polyethylene oxide ono-oleate. 23. An apparatus in accordance with the claim 1, further characterized »in that said surfactant comprises an oleate ester of sorbitol and its copolymer anhydrides with about 20 moles of ethylene oxide for each sorbitol template and sorbitol anhydrides generally of the formula: [The sum of w, x, y, z is 20; R es) C00D 24.- A method for applying a surfactant to at least one surface of at least a first mold part, of a two part mold used for the molding of polymer articles to facilitate the decoupling between said first part of mold from a second part of mold and the removal of any ejection of molding material present on said surface on said first part, said method characterized in that it comprises the steps of: a) moving the support means assembling at least a first mold part to a predetermined location; b) arranging the applicator means including at least one surfactant applicator in spaced relation above the support means, and placing said surfactant applicator in vertical alignment with at least one first mold part; c) coating said surfactant applicator with a layer of surfactant by contacting at least one pad member located in a reservoir containing a supply of said surfactant; d) removing said reservoir containing at least one pad member to a position deviated from at least one surfactant applicator; and e) displacing said applicator means downwardly to the extent that the surface portions wetted by surface active agent of at least one surfactant applicator are brought into contact with at least one surface on said first mold part to impart a coating of said surfactant to the surface. 25. A method according to claim 24, further characterized in that said applicator means comprise stamping means and at least one surfactant applicator comprises a stamping. 26. A method according to claim 25, further characterized in that said embossing means are raised upward to their initial position subsequent to the coating of said surfactant on at least one first mold part; and moving said support means therefrom and inserting at least one successive support means in the position in dich. Location . 27.- A method in accordance with the claim 24, further characterized in that it comprises alternatingly placing at least one pad member below said stamping members and removing said pad member from said location so that at least one pattern advances downward to contact at least one surface on at least one first mold part. 28.- A method in accordance with the claim 27, further characterized in that at least one pad member comprises a porous member that absorbs a solution of said surfactant. 29.- A method in accordance with the claim 28, further characterized in that an upper surface of said porous member is covered by a membrane filter having a mesh size with openings that are in the range of about 0.5 to 0.2 microns. 30.- A method in accordance with the claim 29, further characterized in that said filter is a nylon filter that controls the amount of the surfactant that passes out through said filter in response to the pressure exerted thereon by said stamp upon contacting to deposit a predetermined amount thereby of the surfactant on at least one stamp. 31.- A method according to claim 25, further characterized in that at least the surface portions of said stamp that is in contact with at least one pad member to assume surfactant thereof, is constituted of rubber or of a compound comprising approximately 90% urethane and 10% silicone. 32. A method according to claim 25, further characterized in that a plurality of first mold parts is mounted on the support means forming at least one blade, each of the first mold parts comprising a front curve and a surrounding flange portion for molding a hydrophilic polymer contact lens, each of the first mold portions being operatively aligned with a stamp so that the contact between the facing surface on said flange portion of the front curve and an associated stamp transfers a thin film of said surfactant to said surface from the embossing, thus facilitating the subsequent release of a second mold part by forming a base curve for molding said lenses and a ring of adhesive molding material deposited on said flange surface. 33.- A method according to claim 31, further characterized in that each stamping is mounted elastically on the stamping means to allow each stamping to move in a floating manner with respect to each other when contacting the respective surface in the tab around of the front curve to ensure that even contact is applied thereto and to impart a uniform coating of said tepsioactive agent in each super fi cient. 34. - A method according to claim 24, further characterized in that the surfactant comprises a sorbitan polyethylene oxide mono-oleate. 35. A method according to claim 24, further characterized in that said surfactant comprises an oleate ester of sorbitol and its anhydrides copolymerized with about 20 moles of ethylene oxide for each sorbitol and sorbitol anhydrides, generally of the formula : The sum of w, x, y, z is 20; R is Ct7.Haa) CQQ] 36.- A method according to claim 24, further characterized in that, in addition, approximately 0.05 to 0.50 mg of surfactant is applied to each surface of each mold part. 37. A method according to claim 15, further characterized in that a cover member having at least one opening for at least one pad member is mounted in a sealed manner on said tank. 38.- A method according to claim 37, further characterized in that said cover member is provided with transparent surface portions to be able to see the contents of said tank. METHOD AND APPARATUS FOR APPLYING A SURFACES SURFACE TO SURFACES MOLD SUMMARY OF THE INVENTION A method and apparatus for employing a surfactant is provided to assist in the release of each of the mold components from a multi-part mold used in the molding of polymeric articles, for example, such as a lens. hydrophilic contact, upon completion of the molding process for polymer articles; this surfactant is applied in the form of a film or coating on surface portions of one of the mold components to facilitate uncoupling between the mold components during the demolding, and the removal of the excess of polymeric molding material adhesively deposited on them. its surfaces. GD / crm * ieoh »mvs * cpm *