METHOD FOR ENCAPSULATING A MICROSTRUCTURED LENS BY COATING TRANSFER

A method of forming an optical lens includes providing a lens having microstructures on a surface thereof and an adhesive layer coated thereon; pressing a coating stack, via a carrier layer attached to a first surface of the coating stack by a release coating, against the adhesive layer, a second surface of the coating stack being in contact with the adhesive layer; and curing the adhesive layer and removing the carrier layer from the first surface of the coating stack via the release coating, wherein a thickness of the adhesive layer is greater than a depth of the microstructures on the surface of the lens.

FIELD

The present disclosure relates to a method applying a hard multi-coat on a lens having surface microstructures via a carrier layer.

BACKGROUND

Coatings of microstructured lenses can result in a deviation from the original microlens design, which may require several concept loops to reach a design compensation for each coating. This, in turn, may require longer development times and higher costs. In addition, some microstructured lenses, such as Pi-Fresnel, may not be coated by common methods such as dip or spin coating due to loss of optical design.

Aspects of the disclosure may address some of the above-described shortcomings in the art, particularly with the solutions set forth in the claims.

SUMMARY

The present disclosure relates to a method of forming an ophthalmic lens, including: providing a lens having microstructures on a surface thereof and an adhesive layer coated thereon; pressing a coating stack, via a carrier layer attached to a first surface of the coating stack by a release coating, against the adhesive layer, a second surface of the coating stack being in contact with the adhesive layer; and curing the adhesive layer and removing the carrier layer from the first surface of the coating stack via the release coating, wherein a thickness of the adhesive layer is greater than a depth of the microstructures on the surface of the lens. The present disclosure relates to a method as disclosed in claim1. Advantageous aspects of the method according to the present disclosure are disclosed in claims2to14. The present disclosure additionally relates to an optical element obtained according to the method of the invention and in which the optical element is an ophthalmic lens.

Note that this summary section does not specify every feature and/or incrementally novel aspect of the present disclosure or claimed invention. Instead, this summary only provides a preliminary discussion of different embodiments and corresponding points of novelty. For additional details and/or possible perspectives of the embodiments, the reader is directed to the Detailed Description section and corresponding figures of the present disclosure as further discussed below.

DETAILED DESCRIPTION

The following disclosure provides many different variations, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting nor inoperable together in any permutation. Unless indicated otherwise, the features and embodiments described herein are operable together in any permutation. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, spatially relative terms, such as “top,” “bottom,” “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. Inventive apparatuses may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

As previously mentioned, there may be a need to provide a microstructured lens that can be coated, such as with a hard multi-coat (HMC), without affecting the underlying microstructures formed thereon. To that end, a process leveraging a carrier layer can be used.

Described herein, a HMC can be applied on the microstructured lens surface via a carrier wafer or coating. In particular, the coating carrier can be transferred and adhered onto the target lens surface with an adhesive or bonding fluid that encapsulates the surface microstructures formed thereon.

Described herein, the transfer method includes first casting or molding (e.g., injection molding) a microstructured semi-finished or finished lens and depositing an adhesive on the surface of the lens. Then, a carrier layer with the HMC stack can be pressed against this surface and the adhesive can be cured before removing the carrier. The transfer method allows for the HMC stack to be transferred and adhered to the surface of the lens without imparting undesirable deformation or damage to the surface of the lens.

FIG.1Ais a schematic of an injection molding process to form a lens125, useful within the scope of the present disclosure. In a useful scope, a mold device can include a first mold side101and a second mold side102, a first mold insert198disposed on the first mold side101, and a second mold insert199disposed on the second mold side102. The first mold side101and the second mold side102can each include a hollow portion, wherein the first mold insert198and the second mold insert199can be removeably disposed therein. The first mold insert198can include a plurality of inverted microstructures105formed on a surface of the first mold insert198. The plurality of inverted microstructures105can be a complementary shape to microstructures130on a resulting molded lens125to form the microstructures130during molding. The second mold insert199can have a smooth surface or similarly include a microstructured surface.

The first mold side101with the first mold insert198and the second mold side102with the second mold insert199can be configured to move towards one another to form a cavity or away from one another to open the mold device.

The cavity can be connected to a hollow line formed by the coupling of the first and second mold sides101,102. The line can be configured to receive a polymer melt120, for example, via a screw feeder or similar polymer injector device. The polymer injector can be attached to the mold device and configured to inject the polymer melt120into the cavity when the first mold side101is coupled with the second mold side102to form a lens125from the polymer melt120with the microstructures130based on the plurality of inverted microstructures105and a surface of the second mold insert199facing the cavity. The mold device can stay closed for a first predetermined length of time until the lens125has formed.

FIG.1Bshows an exemplary cross-sectional schematic of a casting process, useful within the scope of the present disclosure. In a useful scope, referring to the first step ofFIG.1B, a gasket205, such as a tape, can be applied around a master mold210to form a well220. For example, the master mold210is a mold insert and includes the plurality of inverted microstructures105. The plurality of inverted microstructures105can be refractive, diffractive, or discontinuous over a portion or an entire surface of the insert. In a second step ofFIG.1B, the well220can be filled with a resin. In a third step ofFIG.1B, the master mold210and the resin filled in the well220can be cured in an oven to form the lens125. The resin can copy an inversion of the plurality of inverted microstructures105on the surface of the master mold210. In a fourth step ofFIG.1B, the gasket205can be removed and the lens125can be released from the master mold210, the lens125replicating the surface of the master mold210to form the microstructures130.

In a useful scope, the lens125can be a thermoplastic or a thermosetting material. Examples of thermoset lens materials include polyurethane, allyl diglycol carbonate, polythiourethane, episulfur polymers, epoxy, poly(meth)acrylates, polythiomethacrylates, or combinations thereof. Examples of thermoplastic lens materials include polycarbonate (referring to homopolycarbonates, copolycarbonates, and block copolycarbonates-polycarbonates can be aromatic or non-aromatic), isosorbide polycarbonate, polyacrylate, (meth)acrylic (co)polymers (especially methyl PMMA), polyvinylbutyral (PVB), thermoplastic polyurethanes (TPU), thermoplastic copolymers of ethylene and vinyl acetate, polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), copolyester, copolymers of polycarbonates and polyesters, copolymers of cycloolefins such as copolymers of ethylene and norbornene or ethylene and cyclopentadiene, and combinations thereof, polystyrene, polyamide, polysulfone, polyphenylsulfone, polyetherimide, polypentene, polyolefin, ionomer, ethylene methacrylic acid, cyclic olefin copolymer, acrylonitrile, styrene maleic anhydride, a copolymer thereof, or a derivative or mixture thereof.

The plurality of inverted microstructures105can be used to mold, for example, refractive micro-structures or diffractive micro/nano-structures. The plurality of inverted microstructures105can be an inversion of a desired final pattern be formed on the resulting lens after molding. The plurality of inverted microstructures105can include microlenses or microlenslets or any other type of structure or elements having physical Z deformation/height or depth between 0.1 micrometer (μm) to 50 μm and width/length between 0.5 μm to 2.0 mm. These structures preferably have periodical or pseudo periodical layout but may also have randomized positions. The preferred layout for microstructures is a grid with constant grid step, honeycomb layout, multiple concentric rings, contiguous e.g., no space in between microstructures. These structures may provide optical wave front modification in intensity, curvature, or light deviation, where the intensity of wave front is configured such that structures may be absorptive and may locally absorb wave front intensity with a range from 0% to 100%, where the curvature is configured such that the structure may locally modify wave front curvature with a range of +/−20 Diopters, and light deviation is configured such that the structure may locally scatter light with angle ranging from +/−1° to +/−30°. A distance between structures may range from 0 (contiguous) to 3 times the structure in “X” and/or “Y” size (separate microstructures).

In the sense of the disclosure, two optical elements located on a surface of a lens substrate are contiguous if there is a path supported by said surface that links the two optical elements and if along said path one does not reach the basis surface on which the optical elements are located. According to another scope, the optical elements are contiguous over a pupil when the optical lens over said pupil comprises no refraction area having a refractive power based on a prescription for said eye of the wearer or a refraction area having a refractive power based on a prescription for said eye of the wearer consisting in a plurality of respectively independent island-shaped areas. According to another scope, the two optical elements are contiguous if there is a path linking the two optical elements along part of said path one may not measure the refractive power based on a prescription for the eye of the person. According to another scope, optical elements being contiguous can also be defined in a surfacic or surface-oriented manner. A measured surface being between 3 mm2and 10 mm2is considered. The measured surface comprises a density of “W” optical elements per mm2. If in said measured surface, at least 95% of the surface, preferably 98%, has an optical power different from the surface onto which the optical elements are located, said optical elements are considered to be contiguous.

Furthermore, microstructures which form a microstructured main surface of an ophthalmic lens substrate may include lenslets. Lenslets may form bumps and/or cavities (i.e., raised or recessed lenslet structures) at the main surface they are arranged onto. The outline of the lenslets may be round or polygonal, for example hexagonal. More particularly, lenslets may be microlenses. A microlens may be spherical, toric, cylindrical, prismatic, or aspherical shapes or any combination to make a multi-element shape. A microlens may have a single focus point, or cylindrical power, or multi-focal power, or non-focusing point. Microlenses can be used to prevent progression of myopia or hyperopia. In that case, the base lens substrate comprises a base lens providing an optical power for correcting myopia or hyperopia, and the microlenses may provide respectively an optical power greater than the optical power of the base lens if the wearer has myopia, or an optical power lower than the optical power of the base lens if the wearer has hyperopia. Lenslets may also be Fresnel structures, diffractive structures such as microlenses defining each a Fresnel structure, permanent technical bumps (raised structures), or phase-shifting elements. It can also be a refractive optical element such as microprisms and a light-diffusing optical element such as small protuberances or cavities, or any type of element generating roughness on the substrate. It can also be π-Fresnel lenslets as described in US2021109379, i.e., Fresnel lenslets which phase function has π phase jumps at the nominal wavelength, as opposition to unifocal Fresnel lenses which phase jumps are multiple values of 2π. Such lenslets include structures that have a discontinuous shape. In other words, the shape of such structures may be described by an altitude function, in terms of distance from the base level of the main surface of the optical lens the lenslet belongs to, which exhibits a discontinuity, or which derivative exhibits a discontinuity. In a useful scope, the microstructure can be a branding mark, holographic mark, metasurface, or the like.

Lenslets may have a contour shape being inscribable in a circle having a diameter greater than or equal to 0.5 micrometers (μm) and smaller than or equal to 2.0 millimeters (mm). Lenslets may have a height, measured in a direction perpendicular to the main surface they are arranged onto, that is greater than or equal to 0.1 μm and less than or equal to 50 μm. Lenslets may have periodical or pseudo periodical layout but may also have randomized positions. One layout for lenslets is a grid with constant grid step, honeycomb layout, multiple concentric rings, contiguous e.g., no space in between microstructures. These structures may provide optical wave front modification in intensity, curvature, or light deviation, where the intensity of wave front is configured such that structures may be absorptive and may locally absorb wave front intensity with a range from 0% to 100%, where the curvature is configured such that the structure may locally modify wave front curvature with a range of +/−20, 500, or 1000 Diopters, and light deviation is configured such that the structure may locally scatter light with angle ranging from +/−10 to +/−30°. A distance between structures may range from 0 (contiguous) to 3 times the structure (separate microstructures).

FIG.2is a schematic of a HMC transfer method, useful within the scope of the present disclosure. In a useful scope, a carrier layer250can be attached to a coating stack or an HMC stack255having at least one layer. A material of the carrier layer250can be, for example, polycarbonate. The carrier layer250can be attached to the HMC stack255by a release coating to facilitate release of the carrier layer250from the HMC stack255.

In a useful scope, the HMC stack255can be disposed on a concave side of the carrier layer250(as shown) and layers in the HMC stack255can be arranged in a reverse order as compared to a standard HMC stack. That is, the carrier layer250can be attached to a first surface of the HMC stack255, wherein the first surface is convex. A second surface of the HMC stack255can be concave and disposed opposite and farthest from the carrier layer250. The HMC stack255can include a hydrophobic top coat (most proximal to the carrier layer250), an anti-reflective coating (which can comprise a stack of sub-layers deposited in reverse of the normal order compared to coating directly onto the lens125), a hardcoating layer, and a latex primer farthest from the carrier layer250. The hydrophobic top coat and the anti-reflective coating can be deposited via vacuum deposition. The hardcoat and the latex primer can be spin coated and cured. Again, the lens125can include the microstructures130on a convex surface of the lens125(as shown).

In a useful scope, the carrier layer250can be attached to the second (concave) surface of the HMC stack255. In such an arrangement, the first (convex) surface of the HMC stack255is disposed opposite and farthest from the carrier layer250. The layers in the HMC stack255can be arranged in an order opposite to when the carrier layer250is attached to the first surface of the HMC stack255. That is, the HMC stack255can include a hydrophobic bottom coat (most proximal to the carrier layer250), an anti-reflective coating (which can comprise a stack of sub-layers deposited in the normal order compared to coating directly onto the lens125), a hardcoating layer, and a latex primer farthest from the carrier layer250.

In a useful scope, an adhesive260(or any fluid for attachment) can be applied to the surface of the lens having the microstructures130. The adhesive260can include light filters such as photochromic dyes or other light filters, which would result in a photochromic microstructured lens125. A predetermined difference or delta in refractive index between the adhesive260and the lens125material, and a predetermined thickness of the adhesive260can be adjusted to preserve the optical function of the microlenses (the microstructures130). For example, a refractive index of the adhesive260can be less than a refractive index of the lens125or a refractive index of the adhesive260can be greater than a refractive index of the lens125. For example, a depth of the microstructures on the surface of the lens is 0.1 μm to 10 μm and a thickness of the adhesive layer is 0.2 μm to 50 μm. For example, a depth of 1 μm can be used for a concentric microlens design. For example, a depth of 5 to 6 μm can be used for a contiguous bifocal microlens design.

The carrier layer250with the attached HMC stack255can be brought into contact with the adhesive260on the lens125such that the HMC stack255is proximal to the adhesive260. As shown, the concave second surface of the HMC stack255is brought into contact with the adhesive260applied to the convex surface of the lens125. A volume of the applied adhesive260can be based on dimensions of the microstructures130, wherein the adhesive260volume sufficiently fills in any depressions or valleys of the microstructures130. Further, a level of the adhesive260can exceed a highest point (a maximum height) of the microstructures130when the HMC stack255contacts the adhesive260. The adhesive260can be cured, for example via high temperature, UV-Vis, etc., before removing the carrier layer250. The transfer method allows for the HMC stack255to be transferred and adhered to the surface of the lens125without causing damage to or altering the microstructures130on the surface of the lens125.

In a useful scope, the HMC stack255includes anti-reflective layers.

In a useful scope, the adhesive260can be cured via UV-Visible actinic radiation to bond the HMC stack255to the lens125before the carrier layer250is removed from the HMC stack255by breaking the bond of the release coating.

In a useful scope, the adhesive260can be cured via high temperature to bond the HMC stack255to the lens125before the carrier layer250is removed from the HMC stack255by breaking the bond of the release coating.

In a useful scope, the HMC stack255includes a latex layer disposed as the last layer in the HMC stack255opposite and furthest from the carrier layer250. The adhesive260can be water or a water-based activating liquid. The HMC stack255can be brought into contact with the water or water-based activating liquid on the surface of the lens125, wherein the latex layer contacts the water or water-based activating liquid. Upon contacting the water or water-based activating liquid, the latex layer can expand. Notably, the expansion of the latex layer can surround and encapsulate the microstructures130to form the bond between the HMC stack255and the lens125. The water can also be heated to facilitate uptake into the latex layer.

Examples

Carrier layer preparation: a 0.5 mm thick plano polycarbonate (PC) carrier layer, having a 2.45 base was fabricated by injection molding. The PC carrier layer was coated by spin coating on its concave side with a protective release coating (see composition in U.S. Pat. No. 7,476,415). A hydrophobic top coat and an anti-reflective coating (including a stack of sub-layers deposited in reverse of the normal order) were deposited by vacuum. A hardcoating solution and a latex primer solution were then deposited by spin coating, and then cured.

Lens preparation: a −2D lens, having a microstructured front surface and 3.25 base front curve was washed, dried, and corona treated on the convex side.

Example 1—A premeasured drop of a UV curable adhesive (for example, OP21 from Dymax Inc.) was placed on the convex side of the lens, and the reverse HMC stack was applied on the adhesive. Pressure was applied to the HMC stack to match a curvature of the HMC stack to a curvature of the lens convex surface. This resulted in the spread of the adhesive between the surface of the lens and the latex primer coating of the carrier layer. The lens/adhesive/HMC stack/carrier layer assembly was placed in a UV curing device to allow the polymerization of the adhesive. After UV curing completion, the pressure was released and the carrier layer was removed. The HMC stack was transferred to the convex surface of the lens via the carrier layer in a way that the microstructures were fully encapsulated by the adhesive and the microstructures were not damaged. The adhesive thickness was higher (or taller) than the depth of the microstructures in order to ensure a full encapsulation. For example, if the microstructures depth is 1 micron, the adhesive thickness can be 1.5 microns or greater.

Example 2—Multiple drops of deionized water were deposited on the convex side of the lens, and the HMC stack including a latex primer layer was applied on (brought into contact with) the water. Pressure was applied to the HMC stack to match a curvature of the HMC stack to a curvature of the lens convex surface. After heating the assembly under pressure (12 PSI, 30 minutes, 110° C.), the assembly was cooled, the pressure was released, and the carrier layer was removed. The HMC stack was transferred to the convex surface of the lens, in a way that the microstructures were fully encapsulated by the latex primer layer and the microstructures were not damaged. The latex primer layer was higher (or taller) than the depth of the microstructures in order to ensure a full encapsulation. For example, if the microstructures depth is 1 micron, the latex primer layer thickness can be 1.5 microns or greater.

Notably, Benefits of the disclosed method include: i) the ability to make Transitions® Stellest™ lenses, and other photochromic lenses with different μ-structures; ii) the ability to coat new myopia control lens designs (such as contiguous μ-lens and Pi-Fresnel) that could not be coated by standard methods such as dip or spin due to loss of optical design; iii) the ability to include light filters in the adhesive or the latex layers, such as blue cut; and iv) the ability to provide a lens surface with a HMC, thus eliminating the need for an additional coating.

FIG.3is an exemplary flow chart for a method300of forming an optical lens, useful within the scope of the present disclosure. In step310, the lens125can be formed having the microstructures130formed on the surface of the lens125, such as the convex surface. In step320, the adhesive260can be applied to the microstructures on the surface of the lens125. In step330, the HMC stack255can be pressed, via the carrier layer250, against the adhesive layer260, wherein the layer opposite and farthest from the carrier layer250in the HMC stack255contacts the adhesive layer260. In step340, adhesive layer260can be cured. In step350, the carrier layer can be removed from the HMC stack255. An optical element can be produced, wherein the optical element is an ophthalmic lens, in particular a spectacle lens.

Those skilled in the art will also understand that there can be many variations made to the operations of the techniques explained above while still achieving the same objectives of the disclosure. Such variations are intended to be covered by the scope of this disclosure. As such, the foregoing descriptions of embodiments are not intended to be limiting. Rather, any limitations to embodiments are presented in the following claims.

Embodiments of the present disclosure may also be as set forth in the following parentheticals.

(1) A method of forming an optical lens, comprising providing a lens (125) having microstructures (130) on a surface thereof and an adhesive layer (260) coated thereon; pressing a coating stack (255), via a carrier layer (250) attached to a first surface of the coating stack (255) by a release coating, against the adhesive layer (260), a second surface of the coating stack (255) being in contact with the adhesive layer (260); and curing the adhesive layer (260) and removing the carrier layer (250) from the first surface of the coating stack (255) via the release coating, wherein a thickness of the adhesive layer (260) is greater than a depth of the microstructures (130) on the surface of the lens (125).

(2) The method of (1), wherein the coating stack (255) is a hard multi-coat stack.

(3) The method of either (1) or (2), wherein the adhesive layer (260) is UV-visible radiation sensitive and the adhesive layer (260) is cured with UV-visible actinic radiation.

(4) The method of any one of (1) to (3), wherein adhesive is temperature sensitive and the adhesive layer (260) is cured at high temperature.

(5) The method of any one of (1) to (4), wherein the adhesive layer (260) is water and the coating stack (255) includes a latex layer disposed at the second surface.

(6) The method of (5), wherein the adhesive layer (260) is cured by pressing the coating stack (255) against the adhesive layer (260) for a predetermined length of time, the predetermined length of time being determined by a length of time needed for the latex layer to absorb the water and for the water to evaporate.

(7) The method of (6), wherein curing the adhesive layer (260) further comprises heating the water to a predetermined temperature to increase water uptake into the latex layer and to expedite evaporation of water.

(8) The method of any one of (1) to (7), wherein the adhesive layer (260) includes a photochromic dye configured to absorb a predetermined wavelength range of electromagnetic radiation.

(9) The method of any one of (1) to (8), wherein a refractive index of the adhesive layer (260) is different from a refractive index of the lens (125).

(10) The method of any one of (1) to (9), further comprising forming the coating stack (255) and the carrier layer (250) by spin coating the release coating onto a surface of the carrier layer (250), the surface of the carrier layer (250) being concave.

(11) The method of (10), further comprising forming the coating stack (255) and the carrier layer (250) by vacuum depositing a hydrophobic topcoat onto the release coating, vacuum depositing an anti-reflective coating onto the hydrophobic topcoat, spin coating a hardcoat solution onto the anti-reflective coating, spin coating a latex primer solution onto the hardcoat solution and curing the hardcoat solution and the latex primer solution.

(12) The method of any one of (1) to (11), further comprising forming the coating stack (255) and the carrier layer (250) by spin coating the release coating onto a surface of the carrier layer (250), the surface of the carrier layer (250) being convex.

(13) The method of any one of (1) to (12), wherein providing the lens (125) with the surface further comprises applying a corona treatment to the surface before applying the adhesive layer (260) to the surface.

(14) The method of any one of (1) to (13), wherein a depth of the microstructures (130) on the surface of the lens (125) is 0.1 μm to 10 μm and a thickness of the adhesive layer (260) is 0.2 μm to 50 μm.

(15) An optical element obtained according to the method of any one of (1) to (14), wherein the optical element is an ophthalmic lens.

(16) The method of any one of (1) to (15), wherein a material of the carrier layer (250) is polycarbonate.

(17) The method of any one of (1) to (16), wherein the coating stack (255) is pressed against the adhesive layer (260) with a force of 12 PSI for at least 30 minutes at a temperature of at least 110° C.

(18) The method of any one of (1) to (17), wherein a material of the lens (125) can be polyurethane, allyl diglycol carbonate, polythiourethane, episulfur polymers, epoxy, poly(meth)acrylates, polythiomethacrylates, or combinations thereof.