Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B3/00—Simple or compound lenses
  • G02B3/0087—Simple or compound lenses with index gradient
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating
  • G02B6/02033—Core or cladding made from organic material, e.g. polymeric material
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4401—Optical cables
  • G02B6/4429—Means specially adapted for strengthening or protecting the cables
  • G02B6/443—Protective covering
  • G02B6/4432—Protective covering with fibre reinforcements
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]

Definitions

• the present invention generally relates to articles coated with a mesoporous sol-gel coating having a refractive index profile such as, for example, optical lenses or optical fibers, preferably made of a plastic material, and more particularly such articles. transparencies with low chromatic aberration, as well as their preparation methods.
• An optical article is characterized by its geometry, thickness and refractive index. The latter is often homogeneous.
• a refractive index profile in an optical material for example a refractive index gradient, provides an additional degree of freedom in the use of the article. Indeed, the refractive index profile makes it possible to vary the optical path of the rays independently of the geometry of the article.
• optical articles comprising a coating having a refractive index profile is in particular to design simpler optical systems of performance equal to that obtained with systems consisting of homogeneous index optical elements.
• Such an embodiment makes it possible, for example, to manufacture optical systems with multiple elements, the number of which would thus be reduced, or to produce glasses or correction lenses of lesser thickness and / or of simpler geometry.
• processes for producing optical articles having a refractive index profile in particular with a radial index gradient. These articles may in particular be obtained by controlled diffusion / polymerization or swelling of a mixture of monomers chosen according to their refractive index, as described in applications EP 0407294, FR 2762098 or EP 0504011.
• the Applicant has set forth a new class of materials with a refractive index profile thanks to the use of mesoporous layers.
• the invention is of particular interest in optics, a field in which substrates made of organic materials are frequently used, in particular transparent organic substrates such as optical or ophthalmic lenses.
• a conventional elimination technique of porogenic agents described for example in WO 03/024869, US Patents 5,858,457 and US 2003/157311, consists in subjecting a substrate coated with a mesostructured film to calcination at high temperature (350-500 ° C.), generally under a flow of oxygen or air for sometimes several hours.
• the present invention firstly relates to an article comprising a substrate having a main surface coated with a coating at least a portion of which is mesoporous, said mesoporous portion having an optical function refractive index profile whose variation is imposed. by the mesopore content and / or the filling rate of the mesopores.
• the refractive index profile of the coating of the invention has an optical function that can be very variable.
• It may be, without limitation, a coating having an anti-reflection function, a coating whose refractive index profile makes it possible to impose a power profile in a localized area of the article, a coating whose refractive index profile makes it possible to impose a power profile, corresponding to a correction for near vision, or a coating whose refractive index profile makes it possible to correct the aberrations.
• the profile in question can in particular be a gradient.
• a refractive index profile can be obtained by creating a porosity profile during the removal of the porogenic agent from the precursor layers of the mesoporous layers.
• the refractive index profile is a radial profile, and preferably a radial gradient.
• the index varies according to the distance to a given axis.
• This type of profile can be obtained, at least locally, by modulating the removal of the pore-forming agent along an axis perpendicular to the optical axis.
• the axis with respect to which the radial profile is defined is preferably the optical axis of the article, but it can also be an axis parallel to the optical axis.
• a radial profile can be obtained by removing the porogenic agent by degradation, and by having used a masking system, which allows for example to regulate the ozone / UV level reaching the surface and thus to control the degree of degradation of the surface. porogenic agent and the filling rate of the mesopores.
• the variation in refractive index is monotonous decreasing along any axis perpendicular to the surface of the substrate underlying the mesoporous portion of said coating and oriented in the direction of the distance from the substrate.
• this profile can be described as "axial.”
• Such a profile can be obtained by depositing on a substrate a stack of mesoporous films made from a composition with a variable content of pore-forming agent, or by partial removal of the pore-forming agent in a given direction of a film.
• FIG. 1 is a schematic representation of the morphology of a mesoporous silica matrix film obtained after removal of the pore-forming agent.
• FIG. 2 is a representation of part of the ternary phase diagram of TEOS / MTEOS / CTAB films, which makes it possible to determine the ordered or unordered structure of a film according to the invention prepared from the CTAB pore-forming agent. , the inorganic precursor agent TEOS and the hydrophobic precursor agent MTEOS. The nature of these different compounds is detailed in the description which follows.
• FIGS. 3 to 6 represent the variation as a function of the wavelength of the reflection coefficient of optical articles coated with a mesoporous film according to the invention.
• the mesoporous portion of the coating of the invention is structured, and any part of the coating of the invention which is not mesoporous is mesostructured.
• the mesoporous materials are defined as solids comprising in their structure pores having a size ranging from 2 to 50 nm, called mesopores. This pore size is intermediate between that of macropores (size> 50 nm) and that of micropores of zeolite type materials (size ⁇ 2 nm).
• Mesopores can be empty, ie filled with air, or only partially empty. Mesopores are usually randomly distributed in the structure, with a wide size distribution.
• the mesoporous portion of a coating refers to that portion in which the blowing agent has at least been partially removed.
• the article according to the invention comprises a substrate having a main surface coated with a coating at least a portion of which is mesoporous, which means that at least one localized area of said coating is mesoporous at least to a certain depth.
• structured materials are defined as materials having an organized structure, characterized more specifically by the existence of at least one diffraction peak in an X-ray diffraction pattern or neutrons.
• the diffraction peaks observed in these types of diagrams may be associated with the repetition of a characteristic distance of the material, called the spatial repetition period of the structured system.
• a mesostructured material is defined as a structured material having a spatial repetition period ranging from 2 to 50 nm.
• Structured mesoporous (or ordered mesoporous) materials are a particular class of mesostructured materials. They are mesoporous materials with an organized spatial arrangement of the mesopores present in their structure, which results in a period of spatial repetition.
• the conventional process for the preparation of mesoporous films, optionally structured mesoporous consists in preparing a low-polymerized sol of an inorganic material such as silica, from a precursor such as a tetraalkoxysilane, in particular tetraethoxysilane (TEOS), this soil also containing water, a generally polar organic solvent such as ethanol and a pore-forming agent, usually in acidic medium.
• a precursor such as a tetraalkoxysilane, in particular tetraethoxysilane (TEOS)
• TEOS tetraethoxysilane
• blowing agent is an amphiphilic agent, for example a surfactant, it acts as a structuring agent and generally leads to structured materials, which will now be explained.
• the concentration of surfactant in the solution is before the deposition much lower than the critical micelle concentration.
• This soil is then deposited on a substrate.
• the organic solvent evaporates, which enriches the film in water, surfactant and silica, then the critical micellar concentration is reached.
• the solvent medium being very polar, the surfactant molecules cluster into clusters, forming micelles with their polar heads towards the solvent.
• the inorganic network eg silica
• the inorganic network grows, and forms because of its very polar nature a matrix around the micelles.
• Composite species consisting of organic micelles coated with inorganic precursors are thus obtained.
• the network grows and traps or encapsulates the micelles inside the solid structure.
• the micelles eventually change shape and self-organize in more or less ordered structures, for example in hexagonal, cubic or lamellar network until the drying of the film.
• the final arrangement of the mineral matrix obtained is governed by the shape of the micelles generated by the amphiphilic molecules used.
• the pore size in the final material depends on the size of the pore-forming agent that is trapped or encapsulated within the silica network.
• a surfactant surfactant
• the pore size in the solid is relatively large because the silica network is built around micelles, that is to say, colloidal particles, formed by the surfactant.
• the micelles are larger in size than their constituents, so that the use of a surfactant as a blowing agent generally produces a mesoporous material.
• blowing agent When the blowing agent is not an amphiphilic agent, it does not form micelles under the conditions of the reaction and does not lead to structured materials.
• this pore-forming agent can optionally be removed from the material, in which case a mesoporous material is obtained.
• a material may be described as mesoporous when the pore-producing agent used for its preparation has been at least partially removed from at least a part of this material, that is to say at least some of this material contains at least partially empty mesopores.
• the removal of the blowing agent can be done by calcination (heating at a temperature generally of the order of 400 ° C.), or by more moderate methods (extraction with solvents, with a supercritical fluid, UV / ozone, plasma).
• silica In the place of silica, it is possible to use other inorganic materials, for example metal or metalloid precursor oxides, especially based on titanium, niobium or aluminum.
• metal or metalloid precursor oxides especially based on titanium, niobium or aluminum.
• the present application relates to two methods of manufacturing an article comprising a substrate having a main surface coated with a coating at least a portion of which is mesoporous and has a refractive index profile as defined above decreasing in the direction of the distance of the substrate.
• the first method of preparing the article comprises at least the following steps: a) providing a substrate; b) preparing a precursor sol of a mesoporous film comprising at least one inorganic precursor agent, at least one porogenic agent, at least one organic solvent, water and optionally a hydrolysis catalyst of the inorganic precursor agent; c) depositing a film of the precursor sol prepared in the previous step on a main surface of the substrate; d) optionally, consolidate the deposited film in the previous step; e) partially removing the blowing agent from at least a portion of the coating comprising the film deposited in step c) so as to create in said portion of the coating a refractive index gradient perpendicular to the surface of the substrate underlying said portion of the coating and directed to the surface of said coating closest to the substrate; f) recovering a substrate having a main surface coated with at least a portion of which is mesoporous.
• the second method of preparing the article comprises at least the following steps: a) providing a substrate; b) preparing a precursor sol of a mesoporous film comprising at least one inorganic precursor agent, at least one porogenic agent, at least one organic solvent, water and optionally a hydrolysis catalyst of the inorganic precursor agent; c) depositing a film of the precursor sol prepared in the previous step on a main surface of the substrate; d) optionally, consolidate the deposited film in the previous step; e) depositing on the film resulting from the preceding step a film of a precursor sol of a mesoporous film comprising at least one inorganic precursor agent, at least one porogenic agent, at least one organic solvent, water and optionally a hydrolysis catalyst of the inorganic precursor agent; f) optionally, consolidate the deposited film in the previous step; g) optionally, repeat steps e) and f) at least once; h) removing the at least partially blowing agent from at least a portion
• the object of the invention comprises a substrate on which is deposited the coating of which at least a portion is mesoporous and has a refractive index profile as defined above.
• the coating may comprise a film of which at least a portion is mesoporous or a stack of several films.
• the coating (or film) at least a portion of which is mesoporous will generally be simply referred to as a mesoporous coating (or film).
• the substrate on which the films are deposited may consist of any solid material, transparent or non-transparent, such as mineral glass, a ceramic, a glass-ceramic, a metal or an organic glass, for example a thermoplastic or thermosetting plastic material.
• the substrate is made of a transparent material and better a transparent organic material.
• thermoplastic materials suitable for substrates mention may be made of
• (meth) acrylic polymers in particular poly (methyl methacrylate) (PMMA),
• thio (meth) acrylic polymers polyvinyl butyral (PVB), polycarbonates (PC), polyurethanes (PU), poly (thiourethanes), polyol allyl carbonates (co) polymers, ethylene / thermoplastic copolymers vinyl acetate, polyesters such as poly (ethylene terephthalate) (PET) or poly (butylene terephthalate) (PBT), polyepisulfides, polyepoxides, polycarbonate / polyester copolymers, cycloolefin copolymers such as ethylene / norbornene or ethylene / cyclopentadiene copolymers and combinations thereof.
• PET poly (ethylene terephthalate)
• PBT poly (butylene terephthalate)
• PBT polyepisulfides
• polyepoxides polycarbonate / polyester copolymers
• cycloolefin copolymers such as ethylene / norbornene or
• (co) polymer is meant a copolymer or a polymer.
• (meth) acrylate is meant an acrylate or a methacrylate.
• alkyl (methacrylates) in particular (C 1 -C 4 ) alkyl (meth) acrylates, such as (meth) acrylate of methyl and ethyl (meth) acrylate, polyethoxylated aromatic (meth) acrylates such as polyethoxylated bisphenol di (meth
• Examples of (co) polymers of polyol allyl carbonates include
• substrates obtained by (co) polymerizing the bis allyl carbonate of diethylene glycol sold, e.g., under the trade name CR 39 ® from PPG Industries (ORMA lens ® ESSILOR).
• substrates obtained by polymerization of thio (meth) acrylic monomers such as those described in French patent application FR 2734827 and polycarbonates.
• the substrates may be obtained by polymerization of mixtures of the above monomers, or may further comprise mixtures of these polymers and (co) polymers.
• all the steps of the first and second processes according to the invention are carried out at a temperature ⁇ 150 ° C., preferably ⁇ 130 ° C., better still ⁇ 120 ° C. and better still ⁇ 110 ° C.
• these processes are compatible with organic substrates.
• the refractive index profile mesoporous coating of the invention may be formed on a major surface of a bare, i.e. uncoated (uncoated) substrate, or on a major surface of a substrate. already coated with one or more functional coatings.
• the substrate of the invention is an ophthalmic lens substrate.
• ophthalmic optics it is well known to coat a main surface of a transparent organic material substrate, for example an ophthalmic lens, with one or more functional coatings to improve the optical and / or mechanical properties of the final lens.
• the main surface of the substrate may be previously provided with a primer coating improving the impact resistance (impact-resistant primer) and / or the adhesion of subsequent layers in the final product, a coating resistant to the abrasion and / or scratches (hard coat), a polarized coating, a photochromic coating, a colored coating, a monolayer or multilayer anti-reflective coating or a stack of two or more thereof coatings.
• the impact-resistant primer coating may be any primer layer conventionally used for articles made of transparent polymeric material, such as ophthalmic lenses.
• compositions based on thermoplastic polyurethanes such as those described in Japanese Pat.
• poly (meth) acrylic primer compositions such as those described in US Pat. No. 5,015,523, compositions based on thermosetting polyurethanes, such as those described in patent EP 0404111 and compositions based on poly (meth) acrylic latex or polyurethane type latex, such as those described in US Patents 5,316,791 and EP 0680492.
• Preferred primer compositions are polyurethane-based compositions and latex-based compositions, particularly polyurethane latices.
• the poly (meth) acrylic latexes are latexes of copolymers consisting mainly of a (meth) acrylate, such as for example ethyl (meth) acrylate, butyl, methoxyethyl or ethoxyethyl, with a generally minor proportion of at least one other comonomer, such as, for example, styrene.
• a (meth) acrylate such as for example ethyl (meth) acrylate, butyl, methoxyethyl or ethoxyethyl
• at least one other comonomer such as, for example, styrene.
• Preferred poly (meth) acrylic latexes are acrylate-styrene copolymer latices.
• Such latexes of acrylate-styrene copolymers are commercially available from Zeneca Resins under the name Neocryl ®.
• Polyurethane latices are also known and commercially available. By way of example, mention may be made of polyurethane latices containing polyester units.
• Such latexes are also marketed by Zeneca Resins under the name NEOREZ ® and the company Baxenden Chemicals under the name WITCOBOND ®.
• the impact-resistant primer may be a primer of high refractive index, that is to say of refractive index greater than or equal to 1.5, or even greater than or equal to 1, 6.
• the refractive index of the primer compositions can be adapted according to the refractive index of the substrate.
• the refractive index of the primer by adding to the primer composition mineral fillers of high refractive index, such as metal oxides (TiC). > 2, Sb 2 O 5 , SnC 2, etc.), optionally composites.
• TiC metal oxides
• primer compositions can also be used in the primer compositions.
• These primer compositions may be deposited on the faces of the article by dipping or centrifugation and then dried at a temperature of at least 70 ° C. and up to 100 ° C., preferably of the order of 90 ° C. , for a duration of 2 minutes to 2 hours, generally of the order of 15 minutes, to form primer layers having thicknesses, after firing, of 0.2 to 2.5 ⁇ m, preferably 0.5 to 1.5 ⁇ m.
• the abrasion-resistant and / or scratch-resistant coatings are preferably hard coatings based on poly (meth) acrylates or silicones.
• hard anti-abrasion and / or anti-scratch coatings recommended in the present invention, mention may be made of coatings obtained from compositions based on silane hydrolysates, in particular epoxysilane hydrolysates such as those described in US Pat. French patent application FR 2702486 and in US Pat. Nos. 4,211,823 and 5,015,523.
• the coating resistant to abrasion and / or scratching may be a coating of high refractive index, that is to say of refractive index greater than or equal to 1, 5 or even greater than or equal to 1.6 .
• colloidal fillers in particular metal oxides such as those mentioned above in the case of in order to increase the refractive index of the anti-abrasion and / or anti-scratch coating.
• a preferred anti-abrasion and / or anti-scratch coating composition is that disclosed in FR 2702486 in the name of the applicant. It comprises a hydrolyzate of epoxy trialkoxysilane and dialkyl dialkoxysilane, colloidal silica and a catalytic amount of aluminum-based curing catalyst such as aluminum acetylacetonate, the remainder consisting essentially of solvents conventionally used to the formulation of such compositions.
• the hydrolyzate used is a hydrolyzate of ⁇ -glycidoxypropyltrimethoxysilane (GLYMO) and dimethyldiethoxysilane (DMDES).
• the mesoporous coating with a refractive index profile which acts as an antireflection coating, is deposited on a substrate coated successively with a layer of anti-shock primer and then with an anti-abrasion and / or anti-scratch coating, or on a substrate directly coated with an anti-abrasion and / or anti-scratch coating.
• the surface of the article on which will be deposited the future mesoporous coating refractive index profile may optionally undergo a pre-treatment to enhance the adhesion of this coating.
• pre-treatments that can be envisaged, mention may be made of corona treatment, vacuum plasma treatment, ion beam treatment, electron beam treatment, or acid or base treatment.
• Step b) of the processes of the invention is a step of preparing a precursor sol of a mesoporous film. Precursor soils of mesoporous films are well known from the state of the art.
• they comprise at least one inorganic precursor agent or a hydrolyzate of this precursor agent, at least one porogenic agent, at least one organic solvent, water, and optionally a catalyst for hydrolysis of the precursor agent. inorganic.
• the precursor sol of a mesoporous film can be obtained by dissolving at least one inorganic precursor agent and at least one porogenic agent in a mixture of water and organic solvent - generally a hydrophilic medium. alcoholic. In some cases, heating may be employed to facilitate the dissolution of the various compounds.
• the soil is, if necessary, cooled and stirred under sufficient conditions (heating may be employed) to allow precursor co-condensation and possibly formation prior to deposition of colloidal particles comprising the dispersed pore-forming agent. inside the growing network. The soil is then ready to be deposited as a film on a main surface of the substrate. It should be noted that in the case of a surfactant, the colloidal particles (micelles) are formed during the deposition step.
• inorganic precursor an organic or inorganic agent which, if polymerized alone, would lead to the formation of an inorganic matrix.
• the inorganic precursor agent is preferably chosen from compounds and mixtures of organometallic or organometalloid compounds of formula:
• M represents a tetravalent metal or metalloid, preferably silicon and X groups, identical or different, are hydrolyzable groups preferably selected from alkoxy, acyloxy and halogen, preferably alkoxy.
• X groups identical or different, are hydrolyzable groups preferably selected from alkoxy, acyloxy and halogen, preferably alkoxy.
• M tetravalent metals represented by M, there may be mentioned metals such as Sn or transition metals such as Zr, Hf or Ti.
• M preferably represents silicon and in this case the compound (I) is the precursor of a matrix based on silica or silicate of at least one metal.
• the alkoxy-OR groups are preferably C 1 -C 4 alkoxy groups
• the acyloxy -O-C (O) R groups are preferably groups in which R is an alkyl radical, preferably a C 1 -C 6 radical, such as methyl or ethyl, and the halogens are preferably Cl, Br or I.
• the groups X are alkoxy groups, and in particular methoxy or ethoxy, and better ethoxy, which makes the inorganic precursor agent (I) a metal alcoholate or metalloid.
• a hydrolysis catalyst of the inorganic precursor agent acts as a condensation catalyst by catalyzing the hydrolysis of the X groups of the compound of formula (I).
• the preferred compounds (I) are tetraalkyl orthosilicates.
• tetraethoxysilane (or tetraethyl orthosilicate) Si (OC 2 Hs) 4 noted TEOS, tetramethoxysilane Si (OCH 3 ) 4 denoted as TMOS, or tetrapropoxysilane Si (OC 3 Hy) 4 denoted TPOS, are advantageously used, and preferably TEOS.
• Inorganic precursor agents present in the soil generally represent
• the organic solvents or the mixture of organic solvents suitable for the preparation of the precursor sol according to the invention are all solvents conventionally used, and more particularly the polar solvents, in particular the alkanols such as methanol, ethanol, isopropanol, propylene glycol, and the like. isobutanol, n-butanol and mixtures thereof.
• Other solvents, preferably water-soluble, may be employed, such as 1,4-dioxane, tetrahydrofuran or acetonitrile.
• the preferred organic solvent is ethanol.
• the organic solvent represents from 40 to 90% by weight relative to the total mass of the precursor sol.
• the water present in the precursor soil generally represents 10 to 20% by weight of the total mass of the precursor soil.
• the medium in which the inorganic precursor agent is present is generally an acidic medium, the acidity of the medium being obtained by adding, for example, a mineral acid, typically HCl or an organic acid such as acetic acid, preferably HCl.
• the pore-forming agent of the precursor sol may be an amphiphilic or non-amphiphilic porogen. Generally, it is an organic compound. It can be used alone or mixed with other blowing agents.
• non-amphiphilic pore-forming agents that can be used in the present invention, mention may be made of: synthetic polymers such as polyethylene oxide, with a molar mass of between 50,000 and 300,000, polyethylene glycol, with a molar mass of between 50,000 and 300,000,
• the blowing agent is preferably an amphiphile of the surfactant type.
• An essential characteristic of such a compound is that it is capable of forming micelles in solution following the evaporation of the solvents which concentrate the solution, to lead to the formation of a mesostructured mineral matrix film. He plays the role of structuring agent.
• the surfactant compounds may be nonionic, cationic, anionic or amphoteric. These surfactants are for the most part commercially available.
• ionic surfactant compounds mention may be made of sodium dodecylbenzene sulphonate, ethoxylated fatty alcohol sulphates and cetyltrimethylammonium bromide. (CTAB), cetyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), azobiscyanopentanoic acid.
• CTAB cetylbenzene sulphonate
• CAC cetyltrimethylammonium chloride
• SDS sodium dodecyl sulfate
• azobiscyanopentanoic acid azobiscyanopentanoic acid.
• nonionic surfactants mention may be made of ethoxylated fatty alcohols, ethoxylated acetylenic diols and compounds of the block copolymer type comprising both hydrophilic blocks and hydrophobic blocks, polyalkylenoxyalkyl ethers and surfactants incorporating a sorbitan group.
• PEO-PPO-PEO Polyoxyethylene-polyoxypropylene-polyoxyethylene
• poly (ethylenoxy) alkyl ethers of the general formula C n H 2n + 1 (OCH 2 CH 2 ) x OH are preferred, in particular those for which n> 12 and x> 8 such as surfactants marketed by ICI under the BRU denominations ®, such as BRIJ 56 ® (C 6 H 33 (OCH 2 CH 2) 10 OH), BRIJ 58 ® (C 6 H 33 (OCH 2 CH 2 ) 20 OH) and BRIJ 76 ® (polyoxyethylene (10) stearyl ether or C 18 H 37 (OCH 2 CH 2) 10 OH).
• BRIJ 56 ® C 6 H 33 (OCH 2 CH 2) 10 OH
• BRIJ 58 ® C 6 H 33 (OCH 2 CH 2 ) 20 OH
• BRIJ 76 ® polyoxyethylene (10) stearyl ether or C 18 H 37 (OCH 2 CH 2) 10 OH
• surfactants incorporating a sorbitan group can be used surfactants marketed by ICI under the name Tween ®, which are polyoxyethylene sorbitan esterified with fatty acids, or surfactants marketed by Aldrich Chem. Co. under the name Span ®, which have a head sorbitan esterified fatty acids.
• the preferred blowing agents are CTAB and diblock or triblock copolymers, preferably triblock, of ethylene oxide and propylene oxide, and of these blowing agents, CTAB is preferred.
• the pore-forming agent represents from 2 to 10% of the total mass of the precursor sol.
• a disadvantage of matrix-only mesoporous films composed of inorganic precursor agents as described above is their low stability in the presence of a moisture-laden atmosphere. These films have a propensity to charge in water over time, which modifies their initial properties.
• hydrophobic groups is meant in the context of the present invention combinations of atoms that are not likely to associate with water molecules, especially by hydrogen bonding. These are usually nonpolar organic groups, free of charged atoms. Alkyl, phenyl, fluoroalkyl, (poly) fluoroalkoxy [(poly) alkyleneoxy] alkyl and hydrogen atom therefore fall into this category.
• the hydrophobic character of the film can be obtained according to two different methods, or in a combination of these two methods.
• the first hydrophobation method involves the introduction of at least one hydrophobic precursor agent carrying at least one hydrophobic group in the precursor sol before the step of depositing the precursor sol film.
• the second hydrophobation method involves the treatment of the film after the deposition step c) or, if it exists, after the consolidation step d), with at least one hydrophobic reactive compound bearing at least one hydrophobic group .
• the inorganic precursor agent and the hydrophobic precursor agent are the two precursor agents of the film matrix, the walls of which will surround the mesopores in the final mesoporous film.
• the hydrophobic precursor agent is preferably chosen from compounds and mixtures of compounds of formulas (II) or (III):
• M represents a tetravalent metal or metalloid, for example Si, Sn, Zr, Hf or Ti, preferably silicon.
• R 1 , R 3 and R 5 which are identical or different, represent saturated or unsaturated, preferably dC 8 and better still C 1 -C 4 hydrocarbon-based hydrophobic groups, for example an alkyl group, such as methyl or ethyl, a group vinyl, an aryl group, for example phenyl, optionally substituted, in particular with one or more C 1 -C 4 alkyl groups, or represent the fluorinated or perfluorinated analogous groups of the abovementioned hydrocarbon groups, for example fluoroalkyl or perfluoroalkyl groups, or (poly) fluoro or perfluoro alkoxy [(poly) alkyleneoxy] alkyl group.
• R 1 , R 3 and R 5 represent the methyl group.
• R 2 , R 4 and R 6 which may be identical or different, represent hydrolysable groups, preferably chosen from alkoxy-OR groups, in particular C 1 -C 4 alkoxy, acyloxy -O-C (O) R, where R is a alkyl radical, preferably C 1 -C 6 , preferably methyl or ethyl, and halogens such as Cl, Br and I. These are preferably alkoxy groups, especially methoxy or ethoxy, and better ethoxy.
• R ' represents a divalent group, for example a linear or branched alkylene group, optionally substituted, an optionally substituted cycloalkylene group, an optionally substituted arylene group or a combination of the abovementioned groups of the same category and / or of different categories, in particular cycloalkylenealkylenes, biscycloalkylenes, biscycloalkylenealkylenes, arylenealkylenes, bisphenylenes and bisphenylenealkylenes.
• Preferred alkylene groups include linear alkylene groups C 1 -C 10, for example the methylene group -CH 2 -, ethylene group - CH 2 -CH 2 -, butylene, hexylene, especially 1, 4- butylene and 1,6-hexylene and C 3 -C 10 branched alkylene radicals such as 1,4 (4-methylpentylene), 1,6 (2,2,4-trimethylhexylene), 1, 5- (5-methylhexylene), 1-6- (6-methylheptylene), 1,5- (2,2,5-trimethylhexylene), 1,7- (3,7-dimethyloctenylene), 2, 2- (dimethylpropylene) and 1, 6- (2,4,4-trimethyl hexylene).
• R 1 is preferably a methylene, ethylene or phenylene group.
• - n is an integer from 1 to 3
• n 2 is an integer from 1 to 3
• n + n 2 4
• Preferred hydrophobic precursor agents are alkylalkoxysilanes, including alkyltrialkoxysilanes such as methyltriethoxysilane (MTEOS, CH 3 Si (OC 2 H 5) 3), the vinylalkoxysilanes include vinyltrialkoxysilanes, such as vinyltriethoxysilane, fluoroalkyl alkoxysilanes including fluoroalkyl trialkoxysilanes such as 3,3,3-trifluoropropyltrimethoxysilane of formula CF 3 CH 2 CH 2 Si (OCH 3 ) 3 and arylalkoxysilanes, especially aryltrialkoxysilanes. Dialkyldialkoxysilanes such as dimethyldiethoxysilane can also be used.
• the most preferred hydrophobic precursor agent is methyltriethoxysilane (MTEOS).
• the molar ratio of the hydrophobic precursor agent to the inorganic precursor agent ranges from 10/90 to 50/50, more preferably from 20/80 to 45/55, and is preferably 40/60, especially when MTEOS is used as a hydrophobic precursor agent in the precursor soil.
• the hydrophobic precursor agent carrying at least one hydrophobic group represents from 1 to 50% by weight relative to the total mass of the precursor sol, and the ratio of the mass of porogenic agents to the sum of the mass of the precursor mass.
• Inorganic precursor agents and the mass of hydrophobic precursor agents carrying at least one hydrophobic group, optionally added in the precursor sol vary from 0.01 to 5, preferably from 0.05 to 1.
• the hydrophobic precursor agent carrying at least one hydrophobic group can be dissolved in the precursor soil of the mesoporous film, or introduced into this precursor sol in the form of a solution in an organic solvent.
• a particularly preferred method for the preparation of the precursor sol of a mesoporous film according to this embodiment of the invention is a two-step process for incorporating the precursor agents, comprising a first step of pre-hydrolysis and condensation in the presence generally an acidic catalyst of the inorganic precursor agent as defined above (forming what will be called a "silica sol" in the case where the inorganic precursor agent is a precursor of silica), followed by a second step mixing with the hydrophobic precursor agent with possibly concomitant introduction of the pore-forming agent.
• the advantage of such a hydrolysis in two steps is to be able to introduce high amounts of hydrophobic precursor agent and to reach a molar ratio of the hydrophobic precursor agent to the inorganic precursor agent as high as 50/50, while preserving a orderly structure in the film.
• the hydrolysis is carried out in an acidic medium, adding water at a pH generally less than 4, more preferably less than 2, and most often from 1 to 2.
• the hydrolysis of the inorganic precursor compound is preferably carried out in the presence of a slight excess of water.
• a quantity of water of 1 to 1.5 times the molar quantity of water required for a stoichiometric hydrolysis of the hydrolyzable groups of compound M (X) is typically used. 4 .
• the reaction is then allowed to continue (aging of the soil).
• the sol is preferably maintained at a temperature of the order of 50 to 70 ° C., typically 60 ° C., for 30 minutes to 2 hours. Condensation can also be carried out at lower temperatures, but with longer condensation times.
• the precursor sol is deposited and the precursor sol film formed rapidly after introduction of the hydrophobic precursor agent in the precursor sol, preferably in a time of 5 minutes or less, and better in a time of two minutes or less. after introduction of the hydrophobic precursor agent into the precursor soil. Proceeding in this very short time allows to minimize the condensation reaction of the hydrophobic precursor agent before the deposition and the formation of the film. In other words, it merely induces partial hydrolysis of the hydrophobic precursor agent without inducing a significant formation of condensed species from this agent.
• the second hydrophobation technique according to the invention will now be described.
• a step of treating the film with at least one Hydrophobic reactive compound carrying at least one hydrophobic group is produced after the deposition step or if it exists after the consolidation step.
• the treatment of the film with the hydrophobic reactive compound or with the mixture of hydrophobic reactive compounds is carried out according to the invention preferably by contact with the hydrophobic reactive compound or with the mixture of hydrophobic reactive compounds in the liquid state or with steam, preferably vapor, with said film.
• the hydrophobic reactive compound is reactive with respect to the silanol groups and treatment with this compound leads to a silica matrix at least part of which silanol groups were derivatized into hydrophobic groups. It is possible to use a large excess of hydrophobic reactive compound relative to the amount of silanol groups to be grafted to accelerate the reaction.
• this additional step is carried out during the step of removing the pore-forming agent.
• This variant is particularly suitable when this removal step is a solvent extraction step.
• the two treatments can be combined by using a solution of hydrophobic reactive agent carrying at least one hydrophobic group in a solvent for extracting the pore-forming agent.
• the additional post-synthetic grafting step is carried out after the step of removing the pore-forming agent.
• This embodiment which involves the treatment of a mesoporous film, is known from the literature and has in particular been described in applications US 2003/157311 and WO 99/09383.
• the additional post-synthetic grafting step is carried out before the step of removing the pore-forming agent.
• the post-synthetic grafting step is common to all layers of said coating.
• Hydrophobic reactive compounds carrying at least one hydrophobic group that is particularly suitable for the present invention are compounds of a tetravalent metal or metalloid, preferentially silicon, comprising a single function capable of reacting with the remaining hydroxyl groups in the film, particular an Si-Cl function,
• said hydrophobic reactive compound is chosen from compounds and mixtures of compounds of formula (IX):
• M represents a tetravalent metal or metalloid, for example Si, Sn, Zr, Hf or Ti, preferably silicon.
• the groups R 1 which may be identical or different, represent saturated or unsaturated, preferably C 1 -C 4 , and preferably C 1 -C 4 , hydrocarbon-based hydrophobic groups, for example an alkyl group, such as methyl or ethyl, a vinyl group or an aryl group; , for example phenyl, optionally substituted, in particular with one or more C 1 -C 4 alkyl groups, or represent the fluorinated or perfluorinated analogous groups of the abovementioned hydrocarbon groups, for example fluoroalkyl, perfluoroalkyl or a (poly) fluoro or perfluoro alkoxy [(poly) alkyleneoxy] alkyl.
• the group R 1 is a methyl group.
• the group R 2 represents a hydrolyzable group, preferably chosen from alkoxy-OR groups, in particular alkoxy groups with dC 4 , acyloxy -O-C (O) R groups, where R is an alkyl radical, preferentially C 1 -C 6 alkyl, preferably methyl or ethyl, amino optionally substituted with one or two functional groups, for example an alkyl or silane group, and halogens such as Cl, Br and I. These are preferably alkoxy groups, especially methoxy or ethoxy, chloro or -NHSiMe groups. 3 .
• a fluoroalkyl chlorosilane especially a tri (fluoroalkyl) chlorosilane or a fluoroalkyl dialkyl chlorosilane such as 3,3,3-trifluoropropyldimethyl chlorosilane of formula CF 3 -CH 2 -CH 2 -Si (CH 3 ) 2 Cl, an alkylalkoxysilane, especially a trialkylalcoxysilane as trimethylmethoxysilane (CH 3) 3 Si0CH 3, an alkoxysilane fluoroalkyl, especially a tri (fluoroalkyl) alkoxysilane or fluoroalkyl dialkyl alkoxysilane, an alkylchlorosilane, in particular a trialkyl chlorosilane such as trimethylchlorosilane, trialkylsilazane or hexaalkyldisilazane.
• the hydrophobic reactive compound comprises a trialkylsilyl group, preferentially a trimethysilyl group, and a silazane group, in particular a disilazane group.
• the particularly preferred hydrophobic reactant compound is 1,1,1,3,3,3-hexamethyldisilazane (CH 3 ) 3 Si-NH-Si (CH 3 ) 3 , denoted HMDS.
• the additional step of post-treatment with said hydrophobic reactive compound is preferably carried out at a temperature ⁇ 150 ° C., preferably ⁇ 130 ° C., better still ⁇ 120 ° C. and better still ⁇ 110 ° C.
• the index-profile coating of the invention may comprise, as the inner layer (closest to the substrate) a layer of a non-mesoporous material such as silica, having a thickness of between 1 and 100 nm. This additional layer may make it possible to improve the performance of said coating, in particular by minimizing its average reflection factor.
• Step c) of depositing the precursor sol film on the main surface of the substrate (or on the additional non-mesoporous layer described above) can be done by any conventional method, for example dip coating, spray deposition or deposition. by centrifugation, preferably by centrifugation.
• the c) deposition step is performed in an atmosphere having a relative humidity (RH) ranging from 40 to 80%.
• the structure of the deposited precursor sol film may optionally be consolidated during a consolidation step, which consists in possibly terminating the removal of the solvent or mixture of organic solvents from the precursor sol film and / or the possible excess of water and continue the condensation, for example residual silanols present in the soil in the case of a matrix based on silica, generally by heating said film.
• a consolidation step is carried out by heating at a temperature ⁇ 150 ° C., preferably ⁇ 130 ° C., better still ⁇ 120 ° C. and better still ⁇ 110 ° C.
• a substrate coated with a precursor film of a mesoporous film that is to say which will lead to a mesoporous film once the pore-forming agent is obtained, is obtained. less partially eliminated.
• the substrate it is possible to deposit on the substrate a single precursor film of a mesoporous film, or a multilayer coating comprising a stack of several mesoporous film precursor films.
• the removal of the pore-forming agent present in a film leads to the production of a mesoporous film, to pores filled with air, the refractive index of said film being lower than that of the initial film.
• a mesostructured film of hexagonal structure 3d and d is obtained.
• refractive index of about 1.48.
• the refractive index after removal of the surfactant depends on the elimination technique chosen but is generally from 1.22 to 1.29 for this CTAB / TEOS molar ratio, and typically about 1.25.
• a mesoporous film with a hydrophobic matrix may have a refractive index of the same order.
• the removal of the blowing agent is carried out by any suitable method for working at low temperature, that is to say at a temperature ⁇ 150 ° C., preferably ⁇ 130 ° C., better ⁇ 120 ° C. C and better still ⁇ 110 0 C.
• the first method of the invention is preferably implemented with substrates coated with a coating comprising a single precursor film of a mesoporous film, or several of these films of identical composition.
• the pore-forming agent is partially removed from at least a portion of the coating comprising the film deposited during step c) so as to create in said portion of the coating an index gradient refraction perpendicular to the surface of the substrate underlying said portion of the coating and directed to the surface of said coating closest to the substrate.
• removal of the pore-forming agent from at least a portion of the coating means that at least a portion of the outer surface of the coating (referred to as the localized area of the coating) is subjected to the removal treatment.
• This spot treatment may affect a layer (film) of the coating or several layers of the coating if it is multilayered.
• the localized areas of the coating surface affected by the removal treatment may have dimensions as small as 0.1 to 200 ⁇ m.
• partial removal of the blowing agent means that it is removed to a certain depth of the coating, and that the final coating will comprise a thickness of which the blowing agent will not have been removed.
• the removal treatment may affect some or all of the outer surface of the coating.
• the partial removal of the pore-forming agent can be carried out by controlled degradation thereof, for example by oxidation by exposure to a plasma, for example oxygen or argon, or ozone generated by for example by UV lamp, by corona discharge or by photo-degradation by means of exposure to light radiation.
• a plasma for example oxygen or argon
• ozone generated by for example by UV lamp by corona discharge or by photo-degradation by means of exposure to light radiation.
• the removal of the blowing agent primarily affects the outer portion of the film, it will have a lower refractive index than the inner portion of the film that will not have undergone the removal process, which whatever the method of elimination used.
• an agent concentration profile is thus obtained.
• a SIMS (Secondary Ion Mass Spectrometry) assay makes it possible to establish the concentration profile by establishing a depth distribution profile of each element (Si, O, C %), just like the RBS (Rutherford Backscattering Spectrometry) technique.
• two categories of mesoporous coatings with a refractive index profile can be obtained: i) the blowing agent has been removed to a certain depth of at least a localized area of the coating: at least one localized area of the coating is mesoporous to a certain depth of said coating; ii) the blowing agent has been removed to a certain depth of the entire coating: the entire coating is therefore mesoporous to a certain depth of said coating.
• FIG. Ii) corresponds to the preferred embodiment of the first method of the invention.
• a substrate is thus recovered having a main surface coated with a coating at least a portion of which is mesoporous, and whose refractive index profile originates from the fact that the Porogenic agent has only been partially removed from the coating.
• the second method of the invention requires the preparation of a stack of at least two precursor films of a mesoporous film, optionally structured (which is generally the case when the blowing agent is of amphiphilic type).
• the refractive index profile presented by the final article is derived from the way in which this stack is created in the context of this second method.
• the coating obtained according to this embodiment of the invention comprises a stack of three layers.
• Step e) of this second process is therefore a step of depositing on the film resulting from the preceding step a film of a sol comprising at least one inorganic precursor agent, at least one porogenic agent, at least one solvent organic, water and optionally a hydrolysis catalyst of the inorganic precursor agent, these components being as defined above, but with the proviso that the pore-forming agent represents a percentage of the total mass of precursor soil higher than that represented by the pore-forming agent in the precursor sol used to form the film obtained in the preceding step.
• This second deposited film may optionally be consolidated during a step f), and, during an optional step g), the sequence of the deposition steps e) and the consolidation step f) may be repeated at least once.
• the pore-forming agent represents a percentage of the total mass of the precursor soil higher than that represented by the porogenic agent in the precursor sol used to form the film obtained in the previous step.
• the deposited stack undergoes a final curing step completing the polymerization, at a temperature ⁇ 150 ° C, preferably ⁇ 130 ° C., better ⁇ 120 ° C. and better still ⁇ 110 ° C.
• the blowing agent is at least partially removed from at least a portion of the coating comprising the films deposited in steps c), e) and where appropriate g), resulting in a substrate having a main surface coated with a multilayer coating at least a portion of which is mesoporous and has a decreasing refractive index profile in the direction of the separation of the substrate along any axis perpendicular to the surface of the substrate underlying said mesoporous portion of said coating.
• the removal of the pore-forming agent firstly affects the outer layers of the multilayer coating, ie the layers furthest away from the substrate, and ultimately the inner layers.
• multilayer coating ie the layers closest to the substrate, regardless of the disposal method used.
• the blowing agent has been removed in the entire volume occupied by the coating; the volume occupied by the coating is therefore mesoporous; ii) the blowing agent has been removed over the entire depth of at least one localized zone of the coating: at least one localized area of the coating is therefore mesoporous over the entire depth of said coating; iii) the blowing agent has been removed to a certain depth of at least one localized area of the coating; iv) the blowing agent was removed to a certain depth of the entire coating.
• the refractive index profile obtained in the coating is not a continuous profile, but a discontinuous profile.
• a step-wise index profile is obtained in the mesoporous portion of the coating corresponding to cases i) and ii).
• the blowing agent is preferably removed to such a depth that only the inner film of the coating, i.e. the film closest to the substrate, is not affected by the elimination, or it is only affected by a certain thickness.
• the refractive index profile originates solely from the fact that the multilayer coating has been constructed by depositing films increasingly loaded with porogenic agents, while that in embodiments iii) and iv), the refractive index profile originates on the one hand because the multilayer coating has been built by depositing films increasingly loaded with porogens, and on the other hand, that the blowing agent is only partially removed from the coating.
• the methods of partial removal of the blowing agent (corresponding to cases iii) and iv) above) that can be used in the second process of the invention are the same as those already described in the context of the present invention.
• first method the methods of removal of the pore-forming agent that may be employed in the case of Figure i) and ii) of the second method of the invention are called "total.”
• total the methods of removal of the pore-forming agent that may be employed in the case of Figure i) and ii) of the second method of the invention.
• the substrate is suitable, or well-known solvent or fluid extraction methods in the supercritical state. It is also possible to use degradation methods, for example by oxidation by exposure to a plasma, for example oxygen or argon, or to ozone generated for example by a UV lamp, by corona discharge or by photo-degradation by means of exposure to light radiation. The latter technique is described in particular in application US 2004/0151651. Extraction with a supercritical fluid (typically supercritical CO 2 ) of a surfactant in a mesostructured material is practiced for example in patent JP 2000-226572.
• the removal of the pore-forming agent is by extraction in the case of Figure i) the second method of the invention. Several successive extractions can be performed, so as to reach the desired level of extraction.
• the extraction is carried out by means of an organic solvent or mixture of organic solvents by quenching the article coated with the coating formed and optionally consolidated in a solvent or a mixture of preferably organic solvents brought to a temperature ⁇ 150 ° C. C.
• a refluxing solvent is preferably used. Any solvent having a boiling point ⁇ 150 ° C., preferably ⁇ 130 ° C., better still ⁇ 120 ° C. and better still ⁇ 110 ° C. may be suitable.
• a non-toxic solvent such as acetone or ethanol is preferably used.
• Acetone is particularly well suited to removal of surfactants of the CTAB or CTAC type by solubilization. Extraction by a
• the solvent can also be effectively carried out at room temperature with the aid of ultrasound, possibly with stirring.
• the films obtained in the cases of figure i) and ii) are extremely porous (fraction of vacuum of approximately 55%). They comprise both mesopores well calibrated, 4 nm in diameter (micelle imprint), and micropores, a few angstroms in diameter, located inside the walls of the matrix, and a priori non-monodisperse.
• the mesopores generally represent 2/3 of the void volume and the micropores generally represent 1/3 of the void volume, which could be determined by subjecting the film to experiments of adsorption.
• FIG. 1 schematically represents the morphology of a mesoporous silica matrix film obtained after at least local removal of the pore-forming agent. In this figure appear two mesopores separated by microporous silica walls.
• the mesoporous part of the final coating can be ordered or not.
• an amphiphilic porogen is preferably used as a structuring agent, so that the mesoporous portion of the final coating generally has an ordered structure.
• a structured film has better mechanical properties, and the means for controlling the reproducibility of its production process are easier.
• ordered or organized structure is meant a structure having a periodic organization in a thickness of at least 20 nm, and in a zone of dimension of at least 20 nm, preferably 300 nm in the plane of the deposited layer.
• the ordered structure may be in particular hexagonal type 3d, cubic or hexagonal 2d, at least locally.
• the hexagonal structure 3d consists of spherical micelles arranged in a network similar to a compact hexagonal stack. His space group is P6 3 / mmc.
• the cubic structure (space group Pm3n) is formed of ellipsoidal and spherical micelles.
• the hexagonal structure 2d (space group c2m) consists of cylindrical micelles.
• FIG. 2 appended to the present application represents a part of the ternary diagram of the phases obtained in the TEOS / MTEOS / CTAB films. It shows which ordered structures (phases) are obtained in the final gel from a soil comprising these three constituents according to the values of their molar ratios.
• MTEOS / TEOS reaches a limit value greater than 1, the films can no longer be structured.
• the mesoporous film according to the invention may have an organized structure hexagonal 3d, cubic or hexagonal 2d, depending on the proportion of CTAB used.
• the CTAB / TEOS molar ratios delimiting the phases move towards values that are higher as the MTEOS / TEOS molar ratio increases.
• the blowing agent is CTAB
• the amounts of the two precursor agents and of the blowing agent are chosen in the steps of preparation of the soil so that the films obtained according to the processes of the invention have an ordered structure of hexagonal 3d type.
• the coatings deposited according to the two processes of the invention generally have a maximum thickness of the order of 1 ⁇ m, and more generally a thickness ranging from 50 to 500 nm.
• optical fibers optical fibers
• optical lenses in particular ophthalmic lenses, especially spectacle lenses, guided optics (optical waveguides), diffraction gratings, Bragg mirrors, insulators for microelectronics, filtration membranes and stationary chromatography phases.
• guided optics optical waveguides
• diffraction gratings optical waveguides
• Bragg mirrors insulators for microelectronics
• filtration membranes filtration membranes
• stationary chromatography phases stationary chromatography phases
• the article has a particular symmetry, it is possible to obtain, for example, an axial, radial or spherical refractive index profile.
• the index In the case of an axial profile, the index varies in a given direction, in the case of a radial profile, the index varies according to the distance to a given axis, in the case of a spherical profile, the index varies according to the distance to a given point.
• An axial or radial profile may in particular be obtained in the case of optical fibers.
• the mesoporous coating with an index profile according to the invention can advantageously be used in optics because it constitutes an achromatic anti-reflection coating. It makes it possible to have articles in particular transparent with anti-reflective properties that perform better than those equipped with a traditional anti-reflection coating of the interferential type, because the average factor of The reflection of the coating of the invention varies less with the wavelength, which makes this type of antireflection more robust to small variations in thickness or index.
• the "average reflection factor” is as defined in the ISO 8980-4 standard, that is to say that it is the average factor of reflection in the visible between 400 and 700 nm , noted R m .
• the average reflection factor in the visible range (400-700 nm) of a coated article according to the invention is less than 2%, better still less than 1% and more preferably less than 0.75%.
• mesoporous silica structures whether or not containing a surfactant-type pore-forming agent, have good mechanical strength.
• the article of the invention is preferably an optical lens, more preferably an ophthalmic lens, or an optical or ophthalmic lens blank.
• the substrate of the article can comprise one or more functional coatings, the refractive index profile coating of the invention can be deposited on any of them, and especially on an anti-abrasion and / or anti-scratch coating.
• the mesoporous coating with a refractive index profile according to the invention may optionally be coated with coatings making it possible to modify its surface properties, such as a hydrophobic and / or oleophobic layer (antifouling top coat) the thickness of which is in general less than 10 nm, preferably 1 to 10 nm, more preferably 1 to 5 nm.
• a hydrophobic and / or oleophobic layer insectifouling top coat
• hydrophobic and / or oleophobic coatings are well known in the art and are generally obtained by conventional thermal evaporation techniques. They are generally made from fluorosilicones or fluorosilazanes, that is to say silicones or silazanes containing fluorine atoms. Fluorosilanes particularly suitable for forming hydrophobic and / or oleophobic coatings are those containing fluoropolyether groups described in US Pat. No. 6,277,485.
• R F is a monovalent or divalent polyfluoropolyether group
• R 1 is a divalent alkylene, arylene or a combination thereof, optionally containing one or more heteroatoms or functional groups and optionally substituted by halogens, and preferably containing 2 at 16 carbon atoms
• R 2 is a lower alkyl group (i.e., a C 1 -C 4 alkyl group)
• Y is a halogen atom, a lower alkoxy group (i.e., a dC 4 alkoxy group, preferably methoxy or ethoxy), or a lower acyloxy group (i.e.
• R 3 is a C 1 -C 4 alkyl group
• x is 0 or 1
• y is 1 (R F is monovalent) or 2 (R F is divalent).
• Suitable compounds generally have a number average molecular weight of at least 1000.
• Y is a lower alkoxy group and R F is a perfluoropolyether group.
• Fluorosilane-containing compositions also recommended for the preparation of hydrophobic and / or oleophobic coatings are described in US Patent 6,183,872. They contain fluoropolymers containing organic groups bearing silicon-based groups represented by the following general formula and having a molecular mass of 5.10 2 to 1.10 5 :
• R F represents a perfluoroalkyl group
• Z is fluoro or trifluoromethyl
• a, b, c, d and e each independently represent 0 or an integer greater than or equal to 1, provided that the sum of a + b + c + d + e is not less than to 1 and that the order of the repetitive units appearing between the parentheses indexed under a, b, c, d and e is not limited to that represented
• Y is H or an alkyl group having 1 to 4 carbon atoms
• X represents a hydrogen, bromine or iodine atom
• R 1 represents a hydroxyl group or a hydrolyzable group
• R 2 represents a hydrogen atom or a monovalent hydrocarbon group
• I represents 0, 1 or 2
• m represents 1, 2 or 3
• n represents an integer at least equal to 1, preferably at least equal to 2.
• a preferred hydrophobic and / or oleophobic coating composition is marketed by Shin-Etsu Chemical under the name KP 801 M® .
• Another composition of hydrophobic and / or oleophobic preferred is commercially available from Daikin Industries under the name OPTOOL DSX ®. It is a fluorinated resin comprising perfluoropropylene groups.
• the substrate on which is formed the mesoporous coating with refractive index profile according to the invention may also be a temporary support, on which said coating is stored, waiting for transfer on a final substrate such as than an ophthalmic lens substrate.
• Said temporary support may be rigid or flexible, preferably flexible. It is a removable medium, that is to say it is intended to be removed once the transfer of the mesoporous coating on the final support.
• the temporary support may be employed having been previously coated with a layer of release agent to facilitate the transfer. This layer may optionally be eliminated at the end of the transfer step.
• the flexible temporary supports are generally thin elements of a few millimeters thick, preferably from 0.2 to 5 mm, better from 0.5 to 2 mm, made of a plastic material, preferably a thermoplastic material.
• thermoplastic (co) polymers that can be used for the manufacture of the temporary support are polysulfones, aliphatic poly (meth) acrylates, such as poly (meth) acrylate, polyethylene, polypropylene, polystyrene, SBM block copolymers (styrene-butadiene-methyl methacrylate), polyphenylene sulphide (PPS), arylene polyoxides, polyimides, polyesters, polycarbonates such as bisphenol A polycarbonate, polyvinyl chloride, polyamides such as nylons, copolymers thereof and mixtures thereof.
• the preferred thermoplastic material is polycarbonate.
• the main surface of the temporary support may comprise a stack of one or more functional coatings (already described) which will be transferred together with the mesoporous coating of the invention to the final support.
• the coatings to be transferred were deposited on the temporary support in the reverse order with respect to the desired stacking order on the final support.
• the invention also relates to a method for transferring the mesoporous coating to a profile. of refractive index (or a stack of coatings comprising said mesoporous coating) of the temporary support to a final substrate.
• the methods of the invention then comprise the following additional step: z) the transfer of said mesoporous coating from the temporary support to a definitive substrate.
• the transfer of the coating or coatings carried by the temporary support can be carried out according to any appropriate technique known to those skilled in the art.
• TEOS of formula Si (OC 2 Hs) 4 was used as an inorganic precursor
• MTEOS of formula CH 3 Si (OC 2 Hs) 3 was used as a hydrophobic precursor
• CTAB of formula C 18 H 33 N + (CH 3 ) 3 , Br " was used as a blowing agent.
• the optical article employed in Examples 1, 2, 5 and 6-9 comprises an ORMA ® ESSILOR lens substrate (having a refractive index of 1.50) coated with the disclosed anti-abrasion and / or scratch-resistant coating. in FR 2702486 (refractive index equal to 1.48 and 3.5 microns thick), based on GLYMO, DMDES, colloidal silica and aluminum acetylacetonate.
• the substrate coated with the abrasion-resistant varnish was subjected to a surface preparation (alkaline attack) prior to deposition of the mesoporous coating of the invention.
• the refractive index of the mesoporous layers is measured at 632.8 nm by ellipsometry. Their thickness is obtained with the profilometer.
• the preparation of the precursor sol of a mesoporous film according to the first method of the invention is a two-step process of incorporation of the precursor agents.
• a silica sol comprising the inorganic precursor is prepared.
• the hydrophobic precursor agent is incorporated in this soil during a second step.
• the silica sol is prepared by hydrolysis of the TEOS and then partial condensation thereof by heating for 1 h at 60 ° C. in dilute hydrochloric acid / ethanol medium in a flask equipped with a condenser.
• the silica sol produced consists of small polymeric clusters of partially condensed silica, with a large amount of silanol functions. These disappear in part if a hydrophobic precursor agent such as MTEOS is introduced into the soil.
• a hydrophobic precursor agent such as MTEOS
• MTEOS hydrophobic precursor agent
• This synthesis was therefore designed so that the set ⁇ polymeric silica cluster + MTEOS ⁇ remains sufficiently hydrophilic not to disturb the hydrophilic-hydrophobic balance of the system.
• the polymerized MTEOS is hydrophobic, unlike the MTEOS hydrolyzed and uncondensed. Synthesis has also been designed to preserve the reactivity of silica clusters (specifically, their rate of gelation), which is usually altered by the presence of MTEOS.
• the substrate coated with the mesostructured film obtained is then consolidated thermally at 110 ° C. for 12 hours.
• Oxygen or Argon Plasma The substrate coated with the mesostructured film is placed in an enclosure provided with two electrodes capable of generating a plasma. After establishing the vacuum in the chamber, the gas is introduced and the plasma is triggered (the flow of gas is maintained or not, the pressure in the chamber is controlled). After exposure to plasma, the contents of the chamber is pumped before recovery of the substrate.
• UV-Ozone Degradation The substrate coated with the mesostructured film is placed in a chamber equipped with a lamp capable of generating the appropriate wavelengths to transform oxygen into ozone (185 and 214 nm).
• the chamber is placed under an atmosphere of oxygen or air (controlled pressure), then the lamp is put into operation. After exposure to ozone, the contents of the chamber are pumped before recovery of the substrate.
• the reflection curve of an article whose mesoporous layer has an index profile obeying a decreasing quadratic function limited by the values 1.47 and 1.25 (example 1) is relatively achromatic. Its average reflection factor in the visible range R m is equal to 1.19%.
• a more efficient coating (Example 2) can be obtained by depositing on the substrate coated with the anti-abrasion and / or anti-scratch coating described above a 20 nm thick silica layer with a refractive index equal to 1.45, then a mesoporous coating 100 nm thick whose refractive index decreases from 1.32 to 1.26 in a quasi-linear profile in the direction of the distance from the substrate (using a CTAB content different from that of ⁇ 2).
• the reflection curve of such an article is achromatic. Its average reflection factor in the visible range (400-700 nm) is equal to 0.55%, which is very powerful.
• the reflection curve of an article whose mesoporous layer has a refractive index profile obeying a decreasing quadratic function bounded by the values 1.479 and 1, 248 (example 3) is not achromatic. Its average reflection factor in the visible range R m is equal to 1.24%. Since the curve is maximum between 500 and 550 nm (2.8%), the average reflection factor weighted by the sensitivity of the eye (R v , from 380 to 780 nm), which is maximum at 550 nm, is high.
• a more efficient coating (Example 4) can be obtained by depositing on the Nikon substrate 1, 67 coated with a coating of 3.5 ⁇ m in thickness and having a refractive index of 1.50, a silica layer of 20 ⁇ m. nm of thickness and refractive index equal to 1.45, then a mesoporous coating of 100 nm in thickness whose refractive index decreases almost linearly from 1.32 to 1.26 in the direction of l distance from the substrate (using a CTAB content different from that of ⁇ 2).
• the reflection spectrum of such an article is almost achromatic. Its average reflection factor in the visible range (400-700 nm) is equal to 0.42%, which is very efficient.
• the average reflection factor weighted by the ocular sensitivity (R v , from 380 to 780 nm) is also very low.
• Examples 3 and 4 prove that the mesoporous refractive index profile coating of the invention is also suitable for high refractive index substrates such as "Nikon 1, 67.”
• the same materials and reagents are used by varying the content of the precursor sol in CTAB so as to prepare a three-layered mesostructured coating comprising, after at least partial removal of the CTAB (the films being described from the substrate to the air):
• the CTAB is removed by extraction by placing the substrate coated with the coating prepared in 1 in acetone at reflux (56 ° C) for 2h. It is also possible to solubilize the CTAB by immersion in refluxing ethanol (78 ° C.) for 5 hours. The removal of CTAB can be followed by FTIR spectroscopy after removing from the mixture and rinsing for a few minutes in acetone coated substrate.
• the reflection curve of such an article is achromatic. Its average reflection factors R m and R v in the visible range are equal to 0.47 and 0.42%, respectively.
• This mesoporous coating with a stepwise refractive index profile is therefore at least as efficient as commercial interference stacks.
• the mesoporous coatings prepared are three-layer coatings whose refractive index profile varies stepwise. They are obtained by successive deposition on the substrate of three layers comprising an increasing proportion of pore-forming agent, so that after removal of the latter, the coating obtained has a decreasing refractive index profile from the substrate to the substrate. 'air.
• Each layer of the coating has a TEOS matrix that has undergone HMDS hydrophobation treatment after that the blowing agent has been eliminated throughout the volume occupied by the three-layer coating (the entire volume occupied by said coating is therefore mesoporous).
• a solution of CTAB in absolute ethanol at 0.0343 g / ml is prepared.
• the dissolution of CTAB is facilitated by sonication.
• 10 mL of the silica sol as prepared in ⁇ A) 1 (when warmed to room temperature) is added to 5 mL of said CTAB solution.
• the first layer is deposited by centrifugation at a speed of 1000 rpm, at a relative humidity of 45-50%, at a temperature of 18-20 ° C., and undergoes a consolidation step (heat treatment: precooking of 15 minutes). at 65 ° C) before the deposition of the subsequent layer.
• the second layer (20 ml of the silica sol is added to 60 ml of a solution of CTAB in absolute ethanol at 0.0137 g / ml, followed by an addition of 80 ml of absolute ethanol) and the third layer (10 mL of the silica sol are added to 42 mL of a solution of CTAB in absolute ethanol at 0.0137 g / mL, followed by an addition of 8 mL of absolute ethanol) are deposited following a procedure similar to that used for the first layer, but with a centrifugation speed of 3000 rpm.
• the stack undergoes a final polymerization step at 100 ° C. for 3 hours.
• a three-layered mesostructured coating is obtained.
• the CTAB located inside the mesopores, is then removed by washing by placing the substrate coated with the three-layered mesostructured coating for 15 minutes in the tank of an Elmasonic brand sonicator (sonicator), containing isopropanol, at room temperature.
• sonicator containing isopropanol
• the homogeneity of the ultrasound is ensured by the start of the "sweep" function of the device.
• a mesoporous coating is obtained, the three layers of which are then rendered hydrophobic, in order to stabilize their refractive index with respect to the water vapor, by placing the substrate coated with the mesoporous coating.
• the mesoporous tri-coated coating of Example 7 is prepared in a manner analogous to that of Example 6.
• the first and second layers of the coating of Example 7 are identical to those of the coating of Example 6.
• the third layer is different (10 ml of the silica sol are added to 50 ml of a solution of CTAB in absolute ethanol at 0.0137 g / ml, thickness: 100 nm).
• the properties and synthesis parameters of the coating are presented in Table 2:
• the mesoporous three-layer coating of Example 8 is prepared in a manner analogous to that of Example 6. It comprises a first layer (10 ml of the silica sol is added to 12 ml of a CTAB solution in the absolute ethanol at 0.0343 g / mL), a second layer (15 mL of the silica sol is added to 48.5 mL of a CTAB solution in 0.0137 g / mL absolute ethanol, followed by an addition of 56 ml of absolute ethanol) and a third layer (10 ml of the silica sol are added to 42 ml of a solution of CTAB in absolute ethanol at 0.0137 g / ml, followed by an addition 8 mL of absolute ethanol).
• Table 3 The properties and synthesis parameters of the coating are presented in Table 3:
• the mesoporous tri-coated coating of Example 9 is prepared in a manner analogous to that of Example 8.
• the first and second layers of the coating of Example 9 are identical to those of the coating of Example 8.
• the third layer is different (10 ml of the silica sol are added to 50 ml of a solution of CTAB in absolute ethanol at 0.0137 g / ml, thickness: 100 nm).
• the properties and synthesis parameters of the coating are presented in Table 4:
• the three-layer mesoporous coatings of Examples 6 to 9 are anti-reflective coatings.
• FIGS. 3 to 6 respectively show the variations of the reflection coefficient as a function of the wavelength of the final optical article on its coated side of the mesoporous coating (for each FIG. top: before removal of the pore-forming agent, bottom curve: after removal of the pore-forming agent and grafting with HMDS).
• Table 5 shows the following optical parameters of these optical articles: the average reflection factor in the visible range R m , the average reflection factor weighted by the ocular sensitivity R v , the hue angle h, and the chroma VS*.

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