Method for preparing a mold part useful for transfering a coating onto an optical substrate

BACKGROUND OF THE INVENTION

1. Field of the invention

0001The present invention relates to a method for forming from a mold optical articles, in particular ophthalmic articles such as ophthalmic lenses, having a hydrophobic top coat thereon.

2. Previous Art

0002It is a common practice in the art to coat at least one face of an ophthalmic lens with several coatings for imparting to the finished lens additional or improved optical or mechanical properties. Thus, it is usual practice to coat at least one face of an ophthalmic lens substrate typically made of an organic glass material with successively, starting from the face of the substrate, an impact-resistant coating (impact-resistant primer), a scratch-resistant coating (hard coat), an anti-reflecting coating and a hydrophobic top coat.

0003Typically, optical articles made of organic glass materials are formed in a mold comprising two separate parts having optical surfaces which, when the two-parts are assembled, define a molding cavity. A liquid curable composition is then introduced in the molding cavity and cured to form the optical article. The optical article is thereafter recovered upon disassembling of the mold parts.

0004Examples of typical two-part molds and molding methods are disclosed in US patents n° 5,547,618 and 5,662,839.

0005It is known in the art to also apply a scratch-resistant coating composition on the optical surfaces of the parts of a two-part mold, and if necessary precure it, assemble the mold parts, fill the molding cavity with an optical liquid curable material, cure the optical material and disassemble the mold parts to recover the molded optical article having a scratch-resistant coating deposited and adhered thereon.

0006Such a method is, for example, disclosed in document EP-102847.

0007US Patent n° 5,096,626 discloses a method for making an optical article having a scratch-resistant coating and/or an anti-reflecting coating thereon, which comprises: <ul id="ul0001" list-style="dash" compact="compact"><li>forming an anti-reflecting coating and/or a scratch-resistant coating onto the optical surfaces of a two-part mold;</li><li>assembling the two-part mold;</li><li>pouring an optical liquid curable composition in the molding cavity;</li><li>curing the optical composition, and</li><li>disassembling the two-part mold for recovering the molded optical article having a scratch-resistant coating or a scratch-resistant coating and an anti-reflecting coating thereon;</li></ul> wherein, either at least one release agent is incorporated into the scratch-resistant coating or a film of at least one release agent is formed on the optical surfaces of the mold parts, prior to the formation of the anti-reflecting coating and/or the scratch-resistant coating.

0008The preferred release agents useful in the method of US-5,096,626 are fluorosilicones, fluoroalkyalkoxysilanes and mixtures thereof.

0009US Patent n° 5,160,668 discloses a method for transferring an anti-reflecting coating onto a surface of an optical element which comprises : <ul id="ul0002" list-style="dash" compact="compact"><li>forming on the optical surface of a part of a two-part mold a release layer of a water soluble inorganic salt;</li><li>forming on said release layer an anti-reflecting layer,</li><li>assembling the mold parts;</li><li>pouring a liquid optical curable composition in the molding cavity,</li><li>curing the optical composition,</li><li>disassembling the mold parts and dissolving the release layer in water to recover the coated optical element.</li></ul>

0010US Patent n° 5,7.33,483 discloses a method for forming on-site tinted and coated optical elements from a mold which comprises: <ul id="ul0003" list-style="dash" compact="compact"><li>forming successively on an optical surface of at least one part of a two-part mold, a polymer release layer, an anti-reflecting coating layer, a coupling agent layer and a hard coat layer;</li><li>assembling the two-part mold;</li><li>pouring an optical liquid curable material in the molding cavity;</li><li>curing the optical material and the anti-reflecting, coupling agent and hard coat layers; and</li><li>disassembling the mold parts to recover the coated optical element.</li></ul>

0011The polymer release layer can be made of a water soluble polymer such as polyvinylic acid (PAA), polyethylene-oxide (PEO), poly(N-vinylpyrolidone) (PNVP), polyvinylalcohol (PVA) or polyacrylamid (PAM); a non-water soluble and UV curable polymer such as polybutadiene-diacrylate (PBD-SA), polyethyleneglycol-diacrylate (PEG-DA) or a highly crosslinked acrylate, and commercial mold release agents such as Dow-Coming 20 Release.

0012The coupling agent layer generally comprises a (meth)acryloxyalkyltrialkoxysilane. This coupling agent layer is used in order to better extract the anti-reflecting coating from the mold.

0013Hydrophobic top coats are classically used for improving dirty mark resistance of finished optical articles, in particular optical articles comprising an anti-reflecting coating.

0014A problem associated with these hydrophobic top coats is their tendency to poorly adhere on the optical substrate and in particular on the anti-reflecting coating of a coated optical substrate.

0015What is needed is a method which will provide easy transfer from a mold of a hydrophobic top coat onto an optical substrate, in particular onto the anti-reflecting coating of a coated optical substrate as well as an improved adhesion of the hydrophobic top coat onto the optical substrate and in particular onto the anti-reflecting coating of a coated optical substrate.

SUMMARY OF THE INVENTION

0016It is an object of this invention to provide a method for preparing at least one mold part of a two-part mold useful for transferring a hydrophobic top coat from a mold onto an optical substrate.

0017It is an additional object of this invention to provide a method for easily transferring a hydrophobic top coat from a mold onto the anti-reflecting coating of a coated optical substrate.

0018It is a further object of this invention to provide a method as above which provides improved adhesion of the hydrophobic top coat onto an optical substrate and in particular onto an anti-reflecting coating of a coated optical substrate.

0019In accordance with the above objects and those that will be mentioned and will become apparent below, there is provided a method for preparing at least one mold part of a two-part mold which comprises : <ul id="ul0004" list-style="none" compact="compact"><li>(a) providing a two-part mold having opposed optical surfaces intended to define therebetween a molding cavity;</li><li>(b) forming a hydrophobic top coat on the optical surface of at least one of the mold parts ;</li><li>(c) forming an anti-reflecting coating onto the hydrophobic top coat, wherein, <ul id="ul0005" list-style="dash" compact="compact"><li>the anti-reflecting coating comprises a stack of dielectric material layers of alternate high and low refractive indices ; and</li><li>the first dielectric material layer deposited on the hydrophobic top coat is deposited using a two-stage process in which, in a first stage, a first sub-layer of dielectric material is deposited by vacuum deposition and, in a second stage, a second sub-layer is deposited by ion assisted vacuum deposition.</li></ul></li></ul>

0020In a preferred embodiment, the mold is made of plastic and in particular polycarbonate or polynorbornene.

0021To further improve release of the coated optical article from the mold, a release agent can be incorporated in the plastic material of the mold, or the optical surfaces of the mold parts can be coated with a release agent layer.

0022In a further preferred embodiment, the method according to the invention comprises, prior to filling the mold with the optical substrate composition, forming onto the hydrophobic top coat an anti-reflecting coating and optionally forming, in the indicated order, a scratch-resistant coating and/or an impact-resistant primer coating.

0023The anti-reflecting coating is typically comprised of a multilayer stack of alternating high and low refractive indices dielectric materials, generally a mineral oxide, which are preferably vacuum deposited.

0024In the most preferred embodiment, the uppermost layer of the stack (which is the first layer of the anti-reflecting stack directly deposited onto the hydrophobic top coat) is vacuum deposited using a two stage process.

0025In a first stage, a first thin sub-layer is deposited by vacuum evaporation of the appropriate dielectric material, directly on the hydrophobic top coat. In a second stage a second thin sub-layer of the same dielectric material is deposited on the first sub-layer using an ion assisted vacuum deposition process. Preferably, the dielectric material of the first layer is SiO₂.

BRIEF DESCRIPTION OF THE DRAWING

0026For the further understanding of the objects and advantages of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like parts are given like reference numerals and wherein: <ul id="ul0006" list-style="none" compact="compact"><li>Figures 1A to 1C schematically illustrate the main steps of an embodiment of the method of the invention.</li></ul>

DETAILED DESCRIPTION OF THE INVENTION

0027Although in the following description, only one face of the optical article is being coated with the optical functional coatings according to the invention, it should be understood that both faces of the optical articles can be coated simultaneously using the method of the invention.

0028With respect to Figure 1A, there is shown schematically a front part 1 of a two-part mold, on the optical surface 1a of which has been successively formed a hydrophobic top coat 10, an anti-reflecting coating 20, a scratch-resistant coating 30 and an impact-resistant primer coating 31.

0029The two-part mold used in the method of the invention comprises a front part 1 having an optical surface 1a and a rear part 2 (Figure 1B) having an optical surface 2a.

0030Typically the two-parts 1, 2 of the mold are assembled through a gasket or an adhesive tape (not shown) so that the optical surfaces 1a, 2a of the mold parts define therebetween a molding cavity.

0031Although the mold parts 1, 2 can be made of any material classically used for making optical lenses such as mineral or organic glasses, these mold parts 1, 2 are preferably made of a plastic material.

0032Among the plastic materials that can be used for the two-part mold there can be cited: polycarbonates (PC), polyamides (PA),polyimides (PI), polysulfones (PS), copolymers of polyethyleneterephtalate and polycarbonate (PET-CP), crystal polyethyleneterephtalate (crystal PET), glass fiber reinforced polyethyleneterephtalate, and polyolefins such as polynorbornenes. The preferred plastic materials are polycarbonates and polynorbornenes.

0033A very good plastic material that can be used for the two part mold is a copolymer having the followings units <chemistry id="chem0001" num="0001"><img file="EP1588829A2_D0001.tif" /></chemistry>

0034Such copolymer is available from Bayer under the commercial trade name APEC.

0035This copolymer has a high rigidity which can be an advantage for the use as a mold material.

0036Typically, the thickness of each mold part (at center of the mold) is of at least 4 mm.

0037However, the method of the present invention may be implemented using rigid or flexible mold parts.

0038The coating bearing surface of the flexible mold is preferably spherical.

0039Flexible mold parts would typically have a thickness of 0.2 to 5 mm, preferably of 0.3 to 5 mm. More preferably, the flexible mold part has a thickness from 0.5 to 1 mm. (at center of the mold).

0040The coated mold part of the invention may be used in any coating transfer method, and in particular in the process as disclosed in WO 03/004255, wherein the coatings are transferred directly onto a preformed lens blank.

0041In that case, the lens blank acts as the second mold part and does not bear any transferable coating.

0042To enhance the release effect of the molds, in particular with regard to the hydrophobic top coating, one or more release agents can be incorporated in the polymer material of the mold. Examples of such release agents are trimethylchlorosilane. Chloromethyltrimethylsilane, chloropropyltrimethylsilane, chloromethyldodecyl dimethylsilane, chlorine terminated polydimethyl siloxane, (3,3-dimethylbutyl) dimethylchlorosilane, hexamethyldisilazane, octamethyltetrasilazane, aminopropyldimethyl terminated polydimethylsiloxane, 3-trimethoxysilyl propyloctadecyldimethylammonium chloride, tetradecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, trimethylethoxysilane and octadecyltrimethoxysilane.

0043If necessary the optical surfaces 1 a, 2a of the parts of the plastic mold may be previously coated with a protective and/or release coating which either protects the optical surfaces from defects such as scratches that may be created during handling. This protective and/or release coating may also even the optical surface and/or enhance the release effect.

0044Examples of such coatings are: <ul id="ul0007" list-style="dash" compact="compact"><li>A UV-curable acrylic layer optionally containing at least one of the above cited release agent or an amine containing polysiloxane layer optionally containing at least one of the above release agent;</li><li>A fluorocarbon polymer layer, such as polytetrafluoroethylene (PTFE) polymers, for example Teflon® AF, Teflon® PTFE FEP and Teflon® PTFE PFA;</li><li>A buffer layer which may delaminate from the mold part optical surface and from which the top coat can release, such as a vacuum-deposited magnesium fluoride (MgF₂) layer or a siloxane base coating normally used to input scratch resistance to lenses. Both of these layers release readily from the optical surface of the mold, in particular of a polycarbonate mold. After demolding of the optical article, these layers are eliminated.</li></ul>

0045The protective and/or release coatings can be deposited by dip coating or spin coating, and depending upon their technical natures they may be UV and/or thermally cured or simply dried. Those protective and/or release coatings have typically a thickness of 2 nm to 10 µm.

0046The mold parts made of plastic material are UV transparent and allow UV and/or thermal curing of the different layers and in particular of the optical substrate composition. Preferably, the polymer material of the mold parts are free of UV absorber.

0047As shown in Figure 1A, there is first deposited on the optical surface 1a of the first part 1 of, for example, a polycarbonate mold, a hydrophobic top coat composition.

0048The hydrophobic top coat 10, which in the finished optical article constitutes the outermost coating on the optical substrate, is intended for improving dirty mark resistance of the finished optical article and in particular of the anti-reflecting coating.

0049As known is the art, a hydrophobic top coat is a layer wherein the stationary contact angle to deionized water is at least 60°, preferably at least 75° and more preferably at least 90°. The stationary contact angle is determined according to the liquid drop method in which a water drop having a diameter smaller than 2 mm is formed on the optical article and the contact angle is measured.

0050The hydrophobic top coats preferably used in this invention are those which have a surface energy of less than 14 m Joules/m².

0051The invention has a particular interest when using hydrophobic top coats having a surface energy of less than 13 m Joules/m² and even better less than 12 m Joules/m².

0052The surface energy values referred just above are calculated according to Owens Wendt method described in the following document: "Estimation of the surface force energy of polymers" Owens D.K. Wendt R.G. (1969) J. Appl. Polym. Sci., 1741-1747.

0053Such hydrophobic top coats are well known in the art and are usually made of fluorosilicones or fluorosilazanes i.e. silicones or silazanes bearing fluor containing groups. Example of a preferred hydrophobic top coat material is the product commercialized by Shin Etsu under the name KP 801 M.

0054The top coat 10 may be deposited onto the optical surface 1 a of mold part 1 using any typical deposition process, but preferably using thermal evaporation technique.

0055Thickness of the hydrophobic top coat 10 usually ranges from 1 to 30 nm, preferably 1 to 15 nm.

0056Anti-reflecting coatings and their methods of making are well known in the art. The anti-reflecting can be any layer or stack of layers which improves the anti-reflective properties of the finished optical article.

0057Preferably, the anti-reflecting coating is a multilayer film comprising three or more dielectric material layers of alternatively high and low refractive indexes.

0058The anti-reflecting coating may preferably consist of a mono- or multilayer film of dielectric materials such as SiO, SiO₂ Si₃N₄, TiO₂, ZrO₂, Al₂O₃, MgF₂ or Ta₂O₅, or mixtures thereof.

0059In particular, the high refractive index materials of the anti-reflecting coating deposited on the mold part may be any high refractive index oxides and their mixtures such as oxides of Zr, Ti, Hf, Ta, Nb, Ce, Y Al, Pr, Mg, In, Sn, Zn, Sc Gd, La or nitrides of such metals, in particular nitrides of Si and Al.

0060The anti-reflecting coating can be applied in particular by vacuum deposition according to one of the following techniques: <ul id="ul0008" list-style="none" compact="compact"><li>1) - by evaporation, optionally ion beam-assisted;</li><li>2) - by spraying using an ion beam,</li><li>3) - by cathode sputtering; or</li><li>4) - by plasma-assisted vapor-phase chemical deposition.</li></ul>

0061In case where the film includes a single layer, its optical thickness must be equal to λ/4 where λ is wavelength of 450 to 650 nm.

0062Of course, the dielectric layers of the multilayer anti-reflecting coating are deposited on the hydrophobic top coat in the reverse order they should be present on the finished optical article.

0063In the embodiment shown in Figure 1A, the anti-reflecting coating 20 comprises a stack of four layers formed by vacuum deposition, for example a first SiO₂ layer 21 having an optical thickness of about 100 to 160 nm, a second ZrO₂ layer 22 having an optical thickness of about 120 to 190 nm, a third SiO₂ layer 23 having an optical thickness of about 20 to 40 nm and a fourth ZrO₂ layer 24 having an optical thickness of about 35 to 75 nm.

0064In order to improve adhesion of the anti-reflecting coating 20 onto the hydrophobic top coat 10 and release of the hydrophobic top coat 10 from the optical surface 1a of mold part 1, the SiO₂ layer 21 of the anti-reflecting coating is deposited on the top coat 10 using a two-stage process.

0065In a first stage a first thin sub-layer of SiO₂ is deposited by vacuum evaporation, directly on the hydrophobic material of the top coat. In a second stage a second thin sub-layer of SiO₂ is deposited on the first sub-layer using a ion assisted vacuum deposition process.

0066The physical thickness of the final SiO₂ layer 21 ranges from 80 to 120 nm (optical thickness 100 to 160 nm).

0067Using the above two stage process as proved to result in good adhesion between the top coat and the anti-reflecting coating.

0068Preferably, after deposition of the four-layer anti-reflecting stack, a thin layer of SiO₂ 25 of 1 to 50 nm thick, is deposited. This layer 25 promotes the adhesion between the anti-reflecting stack and the scratch-resistant coating 30 to be subsequently deposited.

0069The next layer to be deposited is the scratch-resistant coating 30. Any known optical scratch-resistant coating composition can be used to form the scratch-resistant coating 30. Thus, the scratch-resistant coating composition can be à UV and/or a thermal curable composition.

0070By definition, a scratch-resistant coating is a coating which improves the abrasion resistance of the finished optical article as compared to a same optical article but without the scratch-resistant coating.

0071Preferred scratch-resistant coatings are those made by curing a precursor composition including epoxyalkoxysilanes or a hydrolyzate thereof, and a curing catalyst. Preferably, the scratch resistant coating comprises a colloidal filler, especially metal oxide or silica.

0072Preferred scratch resistant coatings comprise silica. Examples of such compositions are disclosed in US 4,211,823, WO 94/10230, US 5,015,523.

0073The most preferred scratch-resistant coating compositions are those comprising as the main constituents an epoxyalkoxysilane such as, for example, γ-glycidoxypropyltrimethoxysilane (GLYMO) and a dialkyldialkoxysilane such as, for example dimethyldiethoxysilane (DMDES), colloidal silica and a catalytic amount of a curing catalyst such as aluminum acetylacetonate or a hydrolyzate thereof, the remaining of the composition being essentially comprised of solvents typically used for formulating these compositions.

0074In order to improve the adhesion of the scratch-resistant coating 30 to the impact-resistant primer coating 31 to be subsequently deposited, an effective amount of at least one coupling agent can be added to the scratch-resistant coating composition.

0075The preferred coupling agent is a pre-condensed solution of an epoxyalkoxysilane and an unsatured alkoxysilane, preferably comprising a terminal ethylenic double bond.

0076Examples of epoxyalkoxysilanes are γ-glycidoxypropyltermethoxysilane, γ-glycidoxypropylpentamethyldisiloxane, γ-glycidoxypropylmethyldiisopropenoxysilane, (γ-glycidoxypropyl)methyldiethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyldiisopropylethoxysilane and (γ-glycidoxypropyl)bis(trimethylsiloxy) methylsilane.

0077The preferred epoxyalkoxysilane is (γ-glycidoxypropyl) trimethoxysilane.

0078The unsatured alkoxysilane can be a vinylsilane, an allylsilane, an acrylic silane or a methacrylic silane.

0079Examples of vinylsilanes are vinyltris(2-methoxyethoxy)silane, vinyltrisisobutoxysilane, vinyltri-t-butoxysilane, vinyltriphenoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldiethoxysilane, vinylmethyldiacetoxysilane, vinylbis(trimethylsiloxy)silane and vinyldimethoxyethoxysilane.

0080Examples of allylsilanes are allyltrimethoxysilane, alkyltriethoxysilane and allyltris (trimethylsiloxy)silane.

0081Examples of acrylic silanes are 3-acryloxypropyltris (trimethylsiloxy) silane, 3-acryloxypropyltrimethoxysilane, acryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethylbis(trimethylsiloxy) silane, 3-acryloxypropyldimethylmethoxysilane, n-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane.

0082Examples of methacrylic silanes are 3-methacryloxypropyltris (vinyldimethoxylsiloxy)silane, 3-methacryloxypropyltris (trimethylsiloxy) silane, 3-methacryloxypropyltris(methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylpentamethyl disiloxane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyldimethyl methoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-methacryloxypropenyltrimethoxysilane and 3-methacryloxypropylbis (trimethylsiloxy)methylsilane.

0083The preferred silane is acryloxypropyltrimethoxysilane. Preferably, the amounts of epoxyalkoxysilane(s) and unsaturated alkoxysilane(s) used for the coupling agent preparation are such that the weight ratio<maths id="math0001" num=""><math display="block"><mrow><mtext>R = </mtext><mfrac><mrow><mtext>weight of epoxyalkoxysilane </mtext></mrow><mrow><mtext>weight of unsaturated alkoxysilane</mtext></mrow></mfrac></mrow></math><img file="EP1588829A2_D0002.tif" /></maths>    verifies the condition 0.8 ≤ R ≤ 1.2.

0084The coupling agent preferably comprises at least 50% by weight of solid material from the epoxyalkoxysilane(s) and unsaturated alkoxysilane(s) and more preferably at least 60% by weight.

0085The coupling agent preferably comprises less than 40% by weight of liquid water and/or organic solvant, more preferably less than 35% by weight.

0086The expression "weight of solid material from epoxyalkoxy silanes and unsatured alkoxysilanes" means the theoretical dry extract from those silanes which is the calculated weight of unit Q_k Si O_(4-k)/2 where Q is the organic group that bears the epoxy or unsaturated group and Q_k Si O_(4-k)/2 comes from Q_k Si R'O_(4-k) where Si R' reacts to form Si OH on hydrolysis.

0087k is an integer from 1 to 3 and is preferably equal to 1.

0088R' is preferably an alkoxy group such as OCH₃.

0089The water and organic solvents referred to above come from those which have been initially added in the coupling agent composition and the water and alcohol resulting from the hydrolysis and condensation of the alkoxysilanes present in the coupling agent composition.

0090Preferred preparation methods for the coupling agent comprises : <ul id="ul0009" list-style="none" compact="compact"><li>1) mixing the alkoxysilanes</li><li>2) hydrolysing the alkoxysilanes, preferably by addition of an acid, such as hydrochloric acid</li><li>3) stirring the mixture</li><li>4) optionally adding an organic solvent</li><li>5) adding one or several catalyst(s) such as aluminum acetylacetonate</li><li>6) stirring (typical duration : overnight).</li></ul>

0091Typically the amount of coupling agent introduced in the scratch-resistant coating composition represents 0.1 to 15% by weight of the total composition weight, preferably 1 to 10% by weight.

0092The scratch-resistant coating composition can be applied on the anti-reflecting coating using any classical method such as spin, dip or flow coating.

0093The scratch-resistant coating composition can be simply dried or optionally precured before application of the subsequent impact-resistant primer coating 31. Depending upon the nature of the scratch-resistant coating composition thermal curing, UV-curing or a combination of both can be used.

0094Thickness of the scratch-resistant coating 30, after curing, usually ranges from 1 to 15 µm, preferably from 2 to 6 µm.

0095Before applying the impact resistant primer on the scratch resistant coating, it is possible to subject the surface of the scratch resistant coating to a corona treatment or a vacuum plasma treatment, in order to increase adhesion.

0096The impact-resistant primer coating 31 can be any coating typically used for improving impact resistance of a finished optical article. Also, this coating generally enhances adhesion of the scratch-resistant coating 30 on the substrate of the finished optical article.

0097By definition, an impact-resistant primer coating is a coating which improves the impact resistance of the finished optical article as compared with the same optical article but without the impact-resistant primer coating.

0098Typical impact-resistance primer coatings are (meth)acrylic based coatings and polyurethane based coatings.

0099(Meth)acrylic based impact-resistant coatings are, among others, disclosed in US-5,015,523 whereas thermoplastic and crosslinked based polyurethane resin coatings are disclosed inter alia, in Japanese Patents 63-141001 and 63-87223, EP-0404111 and US-5,316,791.

0100In particular, the impact-resistant primer coating according to the invention can be made from a latex composition such as a poly(meth)acrylic latex, a polyurethane latex or a polyester latex.

0101Among the preferred (meth)acrylic based impact-resistant primer coating compositions there can be cited polyethyleneglycol(meth)acrylate based compositions such as, for example, tetraethyleneglycoldiacrylate, polyethyleneglycol (200) diacrylate, polyethyleneglycol (400) diacrylate, polyethyleneglycol (600) di(meth)acrylate, as well as urethane (meth)acrylates and mixtures thereof.

0102Preferably the impact-resistant primer coating has a glass transition temperature (Tg) of less than 30°C.

0103Among the preferred impact-resistant primer coating compositions, there may be cited the acrylic latex commercialized under the name Acrylic latex A-639 commercialized by Zeneca and polyurethane latex commercialized under the names W-240 and W-234 by Baxenden.

0104In a preferred embodiment, the impact-resistant primer coating may also include an effective amount of a coupling agent in order to promote adhesion of the primer coating to the optical substrate and/or to the scratch-resistant coating.

0105The same coupling agents, in the same amounts, as for the scratch-resistant coating compositions can be used with the impact-resistant coating compositions.

0106The impact-resistant primer coating composition can be applied on the scratch-resistant coating 30 using any classical method such as spin, dip, or flow coating.

0107The impact-resistant primer coating composition can be simply dried or optionally precured before molding of the optical substrate.

0108Depending upon the nature of the impact-resistant primer coating composition, thermal curing, UV-curing or a combination of both can be used.

0109Thickness of the impact-resistant primer coating 31, after curing, typically ranges from 0.05 to 20 µm, preferably 0.5 to 10 µm and more particularly from 0.6 to 6 µm.

0110The next step of the method is, as shown in Figure 1 B, assembling the front part 1 coated with the hydrophobic top coat, the anti-reflecting, scratch-resistant and impact-resistant primer coatings 20, 30, 31 with the rear part 2 of the two-part mold as described, for example, in US patents 5,547,618 and 5,662,839.

0111The molding cavity is then filled with a liquid curable optical composition which is cured to form the optical substrate 40.

0112The optical substrate can be made from any typical liquid, curable composition used in the optical field.

0113Examples of such optical substrates are substrates resulting from the polymerization of : <ul id="ul0010" list-style="dash" compact="compact"><li>diethylene glycol bis (allylcarbonate) based compositions,</li><li>(meth)acrylic monomer based compositions, such as compositions comprising (meth)acrylic monomers derived from bisphenol-A;</li><li>thio(meth)acrylic monomer based compositions;</li><li>polythiourethane precursor monomer based compositions; and</li><li>epoxy and/or episulfide monomer based compositions.</li></ul>

0114Depending upon the nature of the curable optical material, the optical material can be thermally cured, UV-cured or cured with a combination of both, or cured at ambient temperature.

0115As shown in Figure 1C, once the optical substrate 40 has been cured, and optionally concurrently the scratch-resistant coating 30 and the impact-resistant primer coating 31 if not previously cured, the mold part 10, 11 are disassembled to recover the optical substrate 40 having transferred on one face, the impact-resistant primer coating 31, the scratch-resistant coating 30, the anti-reflecting coating 20 and the hydrophobic top coat 10.

0116The following examples illustrate the present invention. In the examples, unless otherwise stated, all parts and percentages are by weight.

1. Two-part mold

0117In all the examples the mold used was made of polycarbonate (General Electric Company).

2. Hydrophobic top coat

0118Hydrophobic top coat used in the examples is a fluorosilazane commercialized by SHIN ETSU under the name KP 801 M.

3. Scratch-resistant coating compositions (hard coating composition)

0119The following thermal and/or UV curable hard coating compositions were prepared by mixing the components as indicated hereinunder. <tables id="tabl0001" num="0001"><img file="EP1588829A2_D0003.tif" /></tables><tables id="tabl0002" num="0002"><img file="EP1588829A2_D0004.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP1588829A2_D0005.tif" /></tables>

4. Impact-resistant primer coating compositions (primer coating compositions)

0120Several primer coating compositions were made by mixing the various components as indicated below : <tables id="tabl0004" num="0004"><img file="EP1588829A2_D0006.tif" /></tables><tables id="tabl0005" num="0005"><img file="EP1588829A2_D0007.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP1588829A2_D0008.tif" /></tables><tables id="tabl0007" num="0007"><img file="EP1588829A2_D0009.tif" /></tables>

5. Optical substrate compositions

Optical substrate composition n° 1 (UV/Thermally curable)

0121The following mixture was prepared at 40°C in the dark. <tables id="tabl0008" num="0008"><img file="EP1588829A2_D0010.tif" /></tables><tables id="tabl0009" num="0009"><img file="EP1588829A2_D0011.tif" /></tables>

6. Preparation of the mold

0122Unless otherwise stated, the polycarbonate molds used in the examples were prepared as follows : <ul id="ul0011" list-style="none" compact="compact"><li>a) The injection-molded polycarbonate mold is de-gated and then edged. The edging process may create scratches on the surface of the mold, so tape covering of at least the central portion of the mold surface is used during edging.</li><li>b) After edging, the mold is wipped, cleaned in ultrasonic system, and then heated in a clean oven for half an hour at 100°C.</li></ul>

7. Deposition of hydrophobic top coat and anti-reflecting coating

0123Unless otherwise stated, hydrophobic top coat and anti-reflecting coating were deposited on the optical surface of the front part of the mold as follows : <ul id="ul0012" list-style="none" compact="compact"><li>The hydrophobic top coat and anti-reflecting treatments are accomplished in a standard box coater using well known vacuum evaporation practices. <ul id="ul0013" list-style="none" compact="compact"><li>a - The mold is loaded into the standard box coater such as a Balzers BAK760 and the chamber is pumped to a high vacuum level.</li><li>b - Hydrophobic top coat, fluorosilazane (Shin Etsu KP801 M), is deposited onto the optical surface of the first part of the mold using a thermal evaporation technique, to a thickness in the range of 2-15 nm.</li><li>c - The dielectric multilayer anti-reflecting (AR) coating, consisting of a stack of high- and low-index materials is then deposited, in reverse of the normal order. Details of this deposition are as such : <ul id="ul0014" list-style="none" compact="compact"><li>c1 - The first oxide layer in the antireflecting stack to be deposited is SiO₂. This SiO₂ layer is created in a two-stage process. In the first stage, 2-12 nm of SiO₂ is deposited, by vacuum evaporation, directly on the hydrophobic material with no extra energetic assistance during deposition. The SiO₂ deposition is then temporarily halted.</li><li>c2 - After this first amount of SiO₂ has been deposited, the ion source is once again turned on, such that the surface of the SiO₂ is ion bombarded with energetic ions of argon gas, oxygen gas, or a mixture of the two gases.</li><li>c3 - While the surfaces of the lenses are ion bombarded, deposition of SiO₂ is restarted. Because this second stage of SiO₂ deposition is accomplished concurrently with energetic ion bombardment from the ion source, the SiO₂ deposition is considered "ion-assisted". This second stage of SiO₂ film growth deposits approximately of 68-98nm of material. Thus, the total thickness the first of SiO₂ layer (created from these two stages of SiO₂ deposition) is 80-110 nm (optical thickness about 100 to 160 nm).</li><li>c4 - After the first SiO₂ layer deposition sequence is accomplished, the remainder of the four-layer anti-reflecting coating is deposited, in reverse of the normal order, using standard vacuum evaporation deposition techniques, which normally, do not require ion assistance during deposition.</li></ul></li></ul></li><li>The second layer is a layer of ZrO₂ having an optical thickness of about 160 nm, the third layer is a SiO₂ layer having an optical thickness of about 30nm and the fourth layer is a ZrO₂ layer having a thickness of about 55 nm (optical thicknesses are given at a wavelength of 550 nm). <ul id="ul0015" list-style="none" compact="compact"><li>d - At the completion of the deposition of the four-layer anti-reflecting stack, a thin layer of SiO₂, having a physical thickness of 1-50 nm, is deposited. This layer is to promote adhesion between the oxide anti-reflecting stack and the subsequent hard-coating which will be deposited on the coated mold at a later time.</li></ul></li></ul>

EXAMPLE n° 1

0124The front part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Coating Composition n° 1. Hard coating application speed was set at 400 rpm for 8 seconds and spin off speed at 800 rpm for 10 seconds. Hard Coating Composition is cured by IR for 30 seconds with 725F setting, using Lesco IR curing unit. The coated mold was allowed to cool to room temperature and Impact Primer Coating Composition n° 1 a is applied at the same speed and timing as mentioned above. Impact Primer Coating composition is cured by UV light, using Fusion system H bulb with belt speed of (5 feet per minute) 1.526 m/minute.

0125Final coating cure was achieved using Lesco IR curing unit set at 725F for 30 seconds.

0126The coated plastic mold was assembled, filled with optical substrate composition n° 1 and polymerized within 20 minutes. Upon disassembly of the plastic mold, all of the coatings were transferred to the finished lens.

EXAMPLE n° 2

0127The first part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Coating Composition n° 1. Hard coating application speed was set at 400 rpm for 8 seconds and spin off speed at 800 rpm for 10 seconds. Hard Coating Composition cured by IR for 30 seconds with 725F setting, using Lesco IR curing unit. The coated mold was allowed to cool to room temperature and Impact Primer Coating Composition n° 1b was applied at the same speed and timing as mentioned above. Impact Primer Coating Composition was cured by UV light, using Fusion system H bulb with belt speed of (5 feet per minute) 1.524 m/minute.

0128Final coating cure was achieved using Lesco IR curing set at 725F for 30 seconds.

0129The coated plastic mold was assembled, filled with optical substrate Composition n° 1 and polymerized within 20 minutes. Upon disassembly of the plastic mold, all of the coatings were transferred to the finished lens.

EXAMPLE n° 3

0130The front part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Coating Composition n° 2. Hard coating application speed was 500 rpm for 8 seconds and spin off at 1200 rpm for 10 seconds. Hard Coating Composition precured in a thermal heated oven for 10 minutes at 80°C. The coated mold was allowed to cool to room temperature. Impact Primer Coating Composition n° 2 was applied at the application speed 400rpm for 8 seconds and spin off 1000rpm for 10 seconds. Impact Primer Coating was precured at the same temperature and timing as the Hard Coating.

0131Final coating curing was done in a thermal heated oven for 1 hour at 90°C.

0132The coated plastic mold was assembled, filled with optical substrate composition n° 1 and polymerized within 20 minutes. Upon disassembly of the molds, all of the coatings transferred to the finished lens.

EXAMPLE n° 4

0133The front part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Composition n° 3, this hard coating did not contain a coupling agent. Hard coating application speed was 500 rpm. for 8 seconds and spin off. at 1200 rpm. for 10 seconds. Hard Coating was precured in a thermal heated oven for 10 minutes at 80°C. The coated mold was allowed to cool to room temperature. Impact Primer Coating Composition n° 2 was applied at the application speed 400rpm for 8 seconds and spin off 1000rpm for 10 seconds. Impact Primer Coating was precured at the same temperature and timing as the Hard Coating.

0134Final coating curing was done in a thermal heated oven for 1 hour at 90°C.

0135The coated plastic mold was assembled, filled with optical substrate composition n° 1 and polymerized within 20 minutes. Upon disassembly of the mold, all of the coatings transferred to the finished lens.

EXAMPLE n° 5

0136The front part of a polycarbonate two-part mold already coated with a hydrophobic coat and an AR coating was coated with Hard Coating Composition n° 2. Hard coating application speed was 500rpm for 8 seconds and spin off at 1200 rpm. for 10 seconds. Hard Coating was precured in a thermal heated oven for 10min at 80°C. Coated mold was cooled down to room temperature. Impact Primer Coating Composition 3 was applied at the application speed 600rpm for 8 seconds and spin off 1500 rpm for 10 seconds. Impact Primer Coating was precured at the same temperature and timing as Hard Coating Composition n° 2.

0137Final coating curing was achieved in a thermal heated oven for 2 hours at 90°C.

0138The coated molds were assembled, filled with optical substrate composition n° 1 and polymerized within 20 minutes. Upon disassembly of the plastic mold, all of the coatings transferred to the finished lens.

EXAMPLE n° 6

0139The front part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Coating Composition n° 4. Hard coating application speed was set at 600rpm for 8 seconds and spin off speed at 1200 rpm for 10 seconds. Hard Coating was UV cured by Fusion system H bull at (5 feet per minute) 1.524 m/minute and followed by 30 seconds IR cure at 725F for 30 seconds, using Lesco IR curing unit. Coated mold was allowed to cool to room temperature and impact Primer Coating Composition n° 4 was applied at the same speed and timing as mentioned above. Impact Primer Coating was cured by UV light, using Fusion system H bulb with belt speed of (5 feet per minute) 1.524 m/minute.

0140Final coating curing was achieved using Lesco IR curing unit set at 725F for 30 seconds.

0141The coated plastic mold was assembled, filled with optical composition n° 1 and polymerized within 20 minutes. Upon disassembly of the mold, all of the coatings transferred to the finished lens.

EXAMPLE n° 7

0142The front part of a polycarbonate two-part mold already coated with a hydrophobic top coat and an AR coating was coated with Hard Coating Composition n° 4. Hard coating application speed was set at 600 rpm for 8 seconds and spin off speed at 1200 rpm for 10 seconds. Hard Coating UV is cured by Fusion system H bulb at (5 feet per minute) 1.524 m/minute and followed by 30 seconds IR cure at 725F for 30 seconds, using Lesco IR curing unit. Coated mold was allowed to cool to room temperature and Impact Primer Coating n° 5 was applied at the same speed and timing as mentioned above. Impact Primer Coating was cured by UV light, using Fusion SYSTEM H bulb with belt speed of (5 feet per minute) 1.524 m/minute.

0143Final coating curing was achieved using Lesco IR curing unit set at 725F for 30 seconds.

0144The coated plastic mold was assembled, filed with optical substrate Composition n° 1 and polymerized within 20 minutes. Upon disassembly of the mold, all of the coatings transferred to the finished lens.

0145The performances of the finished lenses of examples 1 to 7 A are given in Table below : <tables id="tabl0010" num="0010"><table frame="all"><tgroup cols="6" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="26.25mm" /><colspec colnum="2" colname="col2" colwidth="26.25mm" /><colspec colnum="3" colname="col3" colwidth="26.25mm" /><colspec colnum="4" colname="col4" colwidth="26.25mm" /><colspec colnum="5" colname="col5" colwidth="26.25mm" /><colspec colnum="6" colname="col6" colwidth="26.25mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center">Example n°</entry><entry namest="col2" nameend="col2" align="center">Dry adhesion test</entry><entry namest="col3" nameend="col3" align="center">Bayer abrasion test</entry><entry namest="col4" nameend="col4" align="center">Steel wool test</entry><entry namest="col5" nameend="col5" align="center">Transmission (%)</entry><entry namest="col6" nameend="col6" align="center">Impact energy (mJ)</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">1</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">4.47</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="char" char=".">98.8</entry><entry namest="col6" nameend="col6" align="center">692.40 Tc=1.68 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">2</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">4.73</entry><entry namest="col4" nameend="col4" align="center">1</entry><entry namest="col5" nameend="col5" align="char" char=".">98.8</entry><entry namest="col6" nameend="col6" align="center">1126.60 Tc=2.56 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">3</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">5.35</entry><entry namest="col4" nameend="col4" align="center">0</entry><entry namest="col5" nameend="col5" align="char" char=".">98.9</entry><entry namest="col6" nameend="col6" align="center">711.00 Tc=1.38 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">4</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">4.37</entry><entry namest="col4" nameend="col4" align="center">0</entry><entry namest="col5" nameend="col5" align="char" char=".">98.9</entry><entry namest="col6" nameend="col6" align="center">844.00 Tc=1.46 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">5</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">4.81</entry><entry namest="col4" nameend="col4" align="center">0</entry><entry namest="col5" nameend="col5" align="char" char=".">97.9</entry><entry namest="col6" nameend="col6" align="center">339.80 Tc=1.48 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">6</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">4.22</entry><entry namest="col4" nameend="col4" align="center">0</entry><entry namest="col5" nameend="col5" align="char" char=".">98.8</entry><entry namest="col6" nameend="col6" align="center">62.40 Tc=1.37 mm</entry></row><row><entry namest="col1" nameend="col1" align="center">7</entry><entry namest="col2" nameend="col2" align="center">Well</entry><entry namest="col3" nameend="col3" align="char" char=".">2.66</entry><entry namest="col4" nameend="col4" align="center">5</entry><entry namest="col5" nameend="col5" align="char" char=".">98.6</entry><entry namest="col6" nameend="col6" align="center">849.00 Tc=1.34 mm</entry></row><row rowsep="1"><entry namest="col1" nameend="col6" align="justify">Tc = Thickness at center</entry></row></tbody></tgroup></table></tables>

EXAMPLE n° 8

0146This example illustrates the use of a protective and releasing coating on the optical surfaces of the mold.

0147The composition of the protective and releasing coating was as follows : <tables id="tabl0011" num="0011"><table frame="all"><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><b>Component</b></entry><entry namest="col2" nameend="col2" align="center"><b>Parts by weight</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">PETA LQ (acrylic ester of pentaerythritol)</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PnP</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PM</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">n-propanol</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">1360 (Silicone Hexa-acrylate, Radcure)</entry><entry namest="col2" nameend="col2" align="char" char=".">0.10</entry></row><row><entry namest="col1" nameend="col1" align="center">Coat-O-Sil 3503 (reactive flow additive)</entry><entry namest="col2" nameend="col2" align="char" char=".">0.06</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Photoinitiator</entry><entry namest="col2" nameend="col2" align="char" char=".">0.20</entry></row></tbody></tgroup></table></tables>

0148The polycarbonate molds are cleaned using soap and water and dried with compressed air. The mold surface are then coated with the above protecting and releasing coating composition via spin coating with application speed of 600 rpm for 3 seconds and dry speed of 1200 rpm for 6 seconds. The coating was cured using Fusion Systems H+bulb at a rate of (5 feet per minute) 1.524 m/minute. A hydrophobic top coat and a reverse stack of vacuum deposited AR layers are then applied directly on the above coated molds according to the general procedure described previously. Once AR coating deposition was finished, the molds were coated first with a hard coating composition n° 1 and then with an impact primer coating composition n° 2, cured, and lenses were cast from optical substrate composition n° 1.

EXAMPLE n° 9

0149Example 8 is reproduced except that the mold releasing and protective coating composition was as follows : <tables id="tabl0012" num="0012"><table frame="all"><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><b>Component</b></entry><entry namest="col2" nameend="col2" align="center"><b>Parts by weight</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">PETA LQ (acrylic ester of pentaerythritol)</entry><entry namest="col2" nameend="col2" align="char" char=".">4.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PnP</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PM</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">n-propanol</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">1360 (Silicone Hexa-acrylate, Radcure)</entry><entry namest="col2" nameend="col2" align="char" char=".">2.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Surface active agent</entry><entry namest="col2" nameend="col2" align="char" char=".">0.06</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Photoinitiator</entry><entry namest="col2" nameend="col2" align="char" char=".">0.20</entry></row></tbody></tgroup></table></tables>

0150The whole stack top coat/AR coating/hard coat/primer released well from the coated polycarbonate mold and a lens having very good anti-abrasion, antireflective and impact properties was obtained.

EXAMPLE n° 10

0151Example 8 is reproduced except that the mold releasing and protective coating composition was as follows : <tables id="tabl0013" num="0013"><table frame="all"><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><b>Component</b></entry><entry namest="col2" nameend="col2" align="center"><b>Parts by weight</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">PETA LQ (acrylic ester of pentaerythritol)</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PnP</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Dowanol PM</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">n-propanol</entry><entry namest="col2" nameend="col2" align="char" char=".">5.00</entry></row><row><entry namest="col1" nameend="col1" align="center">Coat-O-Sil 3509 (reactive flow additive)</entry><entry namest="col2" nameend="col2" align="char" char=".">0.10</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Photoinitiator</entry><entry namest="col2" nameend="col2" align="char" char=".">0.20</entry></row></tbody></tgroup></table></tables>

0152The whole stack top coat/AR coating/hard coat/primer released well from the coated polycarbonate mold and a lens having very good anti-abrasion, antireflective and impact properties was obtained.

EXAMPLE n° 11

0153Example 8 is reproduced except that the molds are coated with the following release coating compositions according to the following protocole, before application of the subsequent coatings. <tables id="tabl0014" num="0014"><table frame="all"><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><b>Mold coating composition A :</b></entry><entry namest="col2" nameend="col2" /></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">Deionized water at 60°C</entry><entry namest="col2" nameend="col2" align="char" char=".">0.95</entry></row><row><entry namest="col1" nameend="col1" align="center">A-1100 (gamma aminopropyl trimethoxy silane)</entry><entry namest="col2" nameend="col2" align="char" char=".">0.50</entry></row></tbody></tgroup><tgroup cols="2" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center"><b>Mold coating composition B :</b></entry><entry namest="col2" nameend="col2" /></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">Deionized Water at 60°C</entry><entry namest="col2" nameend="col2" align="char" char=".">0.95</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">Dow Q9-6346 (3-trimethoxysilyl propyl octadecyl dimethylammonium chloride)</entry><entry namest="col2" nameend="col2" align="char" char=".">0.50</entry></row></tbody></tgroup></table></tables>

0154The polycarbonate molds were cleaned using soap and water and dried with compressed air. The molds surfaces were treated by dip coating in the mold coating composition A first for 60 seconds then rinsed off by 60°C deionized water; then they were coated by dip with mold coating composition B and also rinsed off with deionized water at 60°C. The coating composition B was cured using Blue M convection oven at 80°C for 15 min.

0155The whole stack top coat/AR coating/hard coat/primer released well from the coated polycarbonate mold and a lens having very good anti-abrasion, antireflective and impact properties was obtained.

EXAMPLE n° 12

0156Example 8 is reproduced except that the molds were coated with a fluorocarbon polymer layer as a releasing coating.

0157Polycarbonate molds were prepared by cleaning ultrasonically in warmed aqueous detergents, then rinsed and dried according to known art. The polycarbonate molds were then heated to 100°C for a period of time from 0.1-3 hours, to fully dry the material.

0158The molds were then loaded in the vacuum chamber. The chamber is pumped to a vacuum level. Then, the fluoropolymer Teflon was evaporated onto the mold surfaces using either resistance or electron beam heating, to a thickness of 2.5 to 150nm.

0159Alternatively, the fluoropolymer layer was applied to the mold surfaces prior to vacuum deposition by means of spin- or dip-coating, using a dilute solution of soluble fluoropolymers such as Teflon AF, Teflon PTFE FEP, or Teflon PTFE PFA. The thickness of these coatings was 30 to 200nm.

0160After deposition of the fluoropolymer layer, the hydrophobic top coat (KP 801M) and the oxide anti-reflecting multilayer stack were deposited (in reverse of the normal order), using the process described above.

0161KP801M hydrophobic material was evaporated on the fluoropolymer layer using resistance heating. SiO₂ layer, which is the top oxide layer of the AR stack, was then deposited in a two-stage process. The first stage was the deposition of 2-12nm of SiO₂ without ion bombardment, and then the balance of the SiO₂ was depositied with argon ion bombardment, to a total SiO₂ thickness of approximately 85 nm. After the SiO₂ layer, the remaining layers of the stack was deposited by standard evaporative processes.

0162The layer vacuum deposited final was a thin SiO₂ layer after the stack is completed, to promote adhesion of the AR stack to the siloxane-based anti-scratch coating. This layer is not optically active, but is included only to enhance adhesion of the vacuum-deposited AR stack to the anti-scratch coating. Thereafter the other layers were deposited and the lenses cured according to the method described in example 8.

0163The whole stack top coat/AR coating/hard coat/primer released well from the Teflon coated polycarbonate mold and a lens having very good anti-abrasion, anti-reflecting and impact properties was obtained.

EXAMPLE n° 13

0164Example 3 is reproduced, but using optical substrate composition n° 2 instead of optical substrate composition n° 1, which is then cured as follows :

0165The mold parts are taped in order to produce a cavity and filled using a syringe, with the optical substrate composition n° 2.

0166A pre-cure was made in 15 s using a iron doped mercury UV bulb supplied by IST, the intensity was 25-30 mW/cm² (measured 420 nanometer with OM 2 radiometer).

0167Curing was made in IST two side curing oven 2 minutes at 175 mW/cm².

0168Then curing was achieved in a thermal dynamic air oven, at a temperature of 80°C for 8 minutes.

0169The assembly was edged with the plastic molds in order to generate a clear interface to help molds taking a part.

0170The complete stack was transferred to the lens.

EXAMPLE n° 14

0171Example 13 was reproduced, but using optical substrate composition n° 3.

0172The complete stack was transferred to the lens.

EXAMPLE n° 15

0173Example 14 was reproduced but using an allylic formulation using a monomer supplied by PPG under CR607 trade name, catalyzed with 3% by weight of IPP (diisopropylperoxide) and cured using a thermal cycle rising the temperature from 35°C to 85°C in 16 hours.

0174The stack was once against transferred to the lens.

EXAMPLE n° 16

0175Example 13 was reproduced but using an optical substrate composition which comprises 52 g of 1,2-bis (2-mercapto ethyl thio)-3-mercaptopropane with KSCN catalyst 190 ppm mixed with 48g of xylylene diisocyanate.

0176A gel is obtained at room temperature in 5 minutes, curing is achieved at 120°C during 2 hours in air oven.

0177The transfer is made and a very good adhesion is found.

0178The performances of the lenses of examples 13 to 15 are given in Table II below. <tables id="tabl0015" num="0015"><table frame="all"><title>TABLE II</title><tgroup cols="5" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="center">Example n°</entry><entry namest="col2" nameend="col2" align="center">Bayer abrasion test</entry><entry namest="col3" nameend="col3" align="center">Steel wool test</entry><entry namest="col4" nameend="col4" align="center">Dry adhesion</entry><entry namest="col5" nameend="col5" align="center">Transmission (%)</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">13</entry><entry namest="col2" nameend="col2" align="char" char=".">5.6</entry><entry namest="col3" nameend="col3" align="center">2</entry><entry namest="col4" nameend="col4" align="center">Medium</entry><entry namest="col5" nameend="col5" align="char" char=".">98.9</entry></row><row><entry namest="col1" nameend="col1" align="center">14</entry><entry namest="col2" nameend="col2" align="char" char=".">7.1</entry><entry namest="col3" nameend="col3" align="center">9</entry><entry namest="col4" nameend="col4" align="center">Good</entry><entry namest="col5" nameend="col5" align="char" char=".">97.7</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">15</entry><entry namest="col2" nameend="col2" align="char" char=".">6.2</entry><entry namest="col3" nameend="col3" align="center">0</entry><entry namest="col4" nameend="col4" align="center">Good</entry><entry namest="col5" nameend="col5" align="char" char=".">99.1</entry></row></tbody></tgroup></table></tables>

0179Bayer abrasion resistance was determined by measuring the percent haze of a coated and uncoated lens, before and after testing on an oscillating sand abrader as in ASTM F 735-81. The abrader was oscillated for 300 cycles with approximately 500g of aluminum oxide (Al₂O₃) ZF 152412 supplied by Specially Ceramic Grains (former Norton Materials) New Bond Street; PO Box 15137 Worcester, MA 01615-00137. The haze was measured using a Pacific Scientific Hazemeter model XL-211. The ratio of the uncoated lens haze (final-initial) is a measure of the performance of the coating, with a higher ratio meaning a higher abrasion resistance.

0180Steel wool scratch resistance was determined as follows :

0181The lens was mounted coated surface up with double sided tape on the end of a one inch (2.54cm) diameter pivoting rod. Steel wool (000 grade) was then pressed against the coated surface with a five pounds (2.267kg) weight as back-pressure. The lens was then oscillated for 200 cycles against the steel wool (one inch (2.54 cm) travel), and the haze measured. The difference in haze (final-initial) as measured on a Pacific Scientific Hazemeter model XL-211 is reported as the wool scratch resistance value.

0182Coating adhesion was measured by cutting through the coating a series of 10 lines, spaced 1 mm apart, with a razor, followed by a second series of 10 lines, spaced 1 mm apart, at right angles to the first series, forming a crosshatch pattern. After blowing off the crosshatch pattern with an air stream to remove any dust formed during scribing, clear cellophane tape was then applied over the crosshatch pattern, pressed down firmly, and then rapidly pulled away from coating in a direction perpendicular to the coating surface. Application and removal of fresh tape was then repeated two additional times; The lens was then submitted to tinting to determine the percentage adhesion, with tinted areas signifying adhesion failures.

0183Coating passes adhesion tests when percentage adhesion is more than 95%.

0184Transmission was measured using a BYK GARDNER Hazeguard plus hazemeter catalog n°4725.

0185Impact energy was measured using a proprietary system. It can be measured by using the protocol of the FDA drop ball test with increasing weights for the ball up to the breaking of the lens or the appearance of a visual crack, generally having the shape of a star, where the ball impacted. The corresponding energy is then measured.