Process for coating an optical article with an anti-fouling surface coating by vacuum evaporation

[0001] The present invention generally relates to a method of depositing an anti-fouling top coat, especially a fluorinated hydrophobic and / or oleophobic coating, on the outer surface of an optical article by means of vacuum vapor deposition, in particular on a wear and / or scratch resistant coating or on the anti-reflective coating of ophthalmic lenses. The method involves energetic treatment of the optical article and the material to be coated before deposition of the top coat and is particularly valuable when carried out under moderate vacuum.

2. Description of the Related Art [0002] It is common practice in this field to coat at least one lens surface (substrate), such as ophthalmic lenses or lens blanks (eyepieces), with several coatings to provide finished lenses or improved optical or mechanical properties. These coatings are generally referred to as functional coatings.

[0003] Thus, it is normal practice to coat at least one major surface of the lens base, typically made of a material that is organic glass, starting from the surface of the lens base, successively a coating that provides impact resistance (impact resistant primer), an abrasion resistant coating and / or scratching (hard coating), anti-reflective coating, and optionally anti-fouling coating. Other coatings, such as polarizing, photochromic or dyeing coating, may also be applied to one or both of the lens base surfaces.

[0004] The latest generation of ophthalmic lenses most often contain such an outer layer of anti-fouling material deposited on an anti-reflective coating, especially on an anti-reflective coating made of inorganic material, so as to reduce their strong tendency to stain. Such an anti-fouling top coat is generally a hydrophobic and / or oleophobic coating that reduces surface energy so as to avoid adherence of fat deposits, such as fingerprints, sebum, sweat, cosmetics, which are thus easier to remove.

[0005] Such top coatings are well known in the art and are usually made of fluorosilanes or fluorosilazanes, i.e. silicones or silazanes having fluorine-containing groups. Examples of classic materials for top coats are OPTOOL DSX, which is a fluorine resin containing perfluoropropylene moieties, sold by Daikin Industries, KY130 from Shin-Etsu Chemical and KP 801 M, also sold by Shin-Etsu Chemical. These coatings generally give the lens a contact angle of water of at least 95 °.

[0006] The techniques for depositing such anti-fouling top coatings are very different, and include liquid phase deposition, for example dip coating, spincoating (spinning), spray coating or vapor deposition (vacuum vapor deposition). Of these, evaporation deposition is one of the most commonly used techniques.

[0007] Japanese patent application published under JP 2000-308846 (Toppan Printing Co. Ltd) discloses a method of forming an anti-fouling layer on an optical article, including the step of pre-treating the surface of the optical article before depositing the anti-fouling coating by classical methods. As the pre-treatment stage, the high-frequency plasma treatment method, the discharge plasma treatment method, the corona discharge treatment, the electron beam method can be used,

EP1952183B1 ion beam method, acid or base treatment. The anti-fouling layer is deposited by vapor deposition after heating the coating solution under a pressure below 1 Pa, generally below 10^-3 Pa. In the examples, surface pretreatment was obtained using plasma under pressure in the range of 10^-3 up to 10^-1 Pa.

[0008] This method is suitable for numerous applications. However, for technical reasons, such low pressures cannot be obtained with all vacuum chambers, which may not allow a satisfactory anti-fouling top coat to be deposited due to adhesion problems. Indeed, the inventors of the present invention have found that the above method is completely ineffective when carried out in a vacuum chamber at a pressure equal to 10 or higher, as described in more detail in the examples given at the end of the description.

Summary of the Invention [0009] The present invention has been accomplished because of the above problems, and the object of the present invention is to provide a method of depositing an anti-fouling surface coating on the outermost layer of an optical article without encountering problems with adhesion, even if the entire process is carried out under moderate vacuum. By "moderate vacuum" is meant a pressure of at least 10 Pa.

[0010] According to the invention, it has been found that in order to achieve good adhesion at the interface between the outermost layer of the optical article and the anti-fouling top coat, it is necessary to carry out treatment with energetic particles of both the outermost layer of the optical article and the coating material for the anti-fouling top coat before the latter is deposited.

[0011] In order to achieve the above objectives, and according to the invention as it is implemented and extensively described herein, the present invention relates to a method of depositing an anti-fouling top coat on the outermost coating layer of a coated optical article, comprising the following steps:

(a) providing an optical article having two main facing sides, at least one of which is coated with the outermost layer;

b) treatment of said outermost layer with energetic particles causing physical attack and / or chemical modification; and

c) vacuum evaporation of the liquid coating material for the top anti-fouling coating by means of a vaporization device, which causes the deposition of the evaporated coating material on the outermost layer of the optical article to be treated, in which said liquid coating material has been treated with energetic particles prior to the vaporization stage of the liquid coating material.

[0012] A variant of the deposition method was then designed in which said liquid coating material and said outermost layer of the optical article are simultaneously subjected to the same treatment with energetic particles.

[0013] In preferred embodiments, the energy treatment is plasma treatment and the evaporation device is an electrical circuit connected to a steel wool element on which a liquid coating material for an anti-fouling top coat is deposited.

[0014] Other objects, features and advantages of the present invention will become apparent from the present description. It should be understood, however, that the detailed description and specific examples, indicating specific embodiments of the invention, are given for illustration only, because from this detailed description various changes and modifications obvious to those skilled in the art will be apparent to those skilled in the art.

EP1952183B1

Detailed Description of the Invention and Preferred Embodiments [0015] The terms "include" (and all forms of the verb include, such as "includes" and "including"), "have" (and all forms of the verb have, such as "has" and "having" ), "Contain" ((and all forms of the verb contain, such as "contains" and "containing"), and "enable" (and any forms of the verb enable, such as "on" and "enabled") are open connecting verbs. As a result, a method or method step that "includes," "has," "includes," or includes "one or more stages or elements, has one or more stages or elements, but is not limited to having only that one or more. stages or elements.

[0016] The optical articles used in the method of the invention are preferably optical lenses. The term "lenses" herein means organic or inorganic glass lenses, including a lens base (s) that can be coated with one or more different types of coating.

[0017] When the optical article includes one or more surface coatings, the term "depositing a layer on the optical article" means that the layer is deposited on the outermost coating of the optical article.

[0018] By the outermost layer or coating of the coated optical article is meant the outer coating layer or coating of the optical article during the coating step in which the anti-fouling coating has not yet been deposited. The outermost layer or coating here is the layer or coating on which the anti-fouling top coat is deposited according to the invention. Said outermost layer or coating of the optical article is generally a mono- or multi-layer anti-reflective coating or abrasion and / or scratch resistant coating (hard coating), preferably an abrasion and / or scratch resistant coating (hard coating).

[0019] According to the invention, a method is provided for depositing an anti-fouling top coating on the outermost coating layer of a coated optical article, preferably ophthalmic lenses, by vapor deposition of a coating material, preferably a liquid, which comprises the steps of treating said outermost layer with energetic particles, but also said liquid coating material prior to the vacuum deposition step.

[0020] Although the lens base can be made of mineral glass or organic glass, it is preferably made of organic glass. Organic glasses can be either bases based on thermoplastic materials, such as polycarbonates and thermoplastic polyurethanes, or thermosetting (cross-linked) materials, such as diethylene glycol bis (allyl carbonate) polymers and copolymers (in particular CR39^® from PPG Industries), thermosetting polyurethanes, polythiourethanes, polyepoxides, polypisulfides, poly (meth) acrylates and copolymers such as bases containing polymers and (meth) acrylic copolymers derived from bisphenol-A, polythio (meth) acrylates, and their copolymers and their blends. Preferred lens base materials are polycarbonates and copolymers of diethylene glycol bis (allyl carbonate), in particular bases made of polycarbonate.

[0021] The coated optical article, the outermost layer of which is coated by the method of the invention, may contain conventional functional coatings, such as one or more coatings selected from: anti-reflective coating (AR coating), wear and / or scratch resistant coating, coating suitable impact resistance, polarizing coating, photochromic coating, colored coating.

[0022] Preferably, the functional coatings used in the present invention are selected from the group consisting of an impact resistant coating, an abrasion and / or scratch resistant coating, and an anti-reflective coating. Most preferably, the optical article used herein is coated with these coatings in the order in which they are listed, starting from the surface of the optical article.

EP1952183B1 [0023] The coating providing impact resistance may be any coating used to improve the impact resistance of the finished optical article. This coating also generally increases the adhesion of the scratch resistant coating to the base of the finished optical article. By definition, a primer coating that provides impact resistance is a coating that improves the impact resistance of a finished optical article compared to the same optical article, but without a primer coating that provides impact resistance.

[0024] Typical primers that provide impact resistance are (meth) acrylic polymer based coatings and polyurethane based coatings. Impact coatings based on (meth) acrylic polymers are inter alia disclosed in US Patent Nos. 5,015,523 and 6,503,631, while coatings based on thermoplastic and cross-linked polyurethane resins are disclosed, among others, in Japanese Patent Nos. 63-141001 and 63-87223, European No. 0404111 and US Patent No. 5,316,791.

[0025] In particular, the primer coating providing impact resistance according to the invention may be made of a latex composition such as poly (meth) acrylic latex, polyurethane latex or polyester latex.

[0026] Among the preferred primer coating compositions based on (meth) acrylate, mention may be made of compositions based on polyethylene glycol (meth) acrylate, such as, for example, tetraethylene glycol diacrylate, polyethylene glycol diacrylate (200), polyethylene glycol diacrylate (400), glycol diacrylate polyethylene (600), and urethane (meth) acrylates and mixtures thereof.

[0027] Preferably, the primer coating that provides impact resistance has a glass transition temperature (Tg) below 30 ° C. Preferred primer coating compositions include acrylic latex sold under the name Akrylic latex A-639 by Zeneca and polyurethane latex sold under the names W-240 and W-234 by Baxenden.

[0028] In a preferred embodiment, the primer coating that provides impact resistance may also contain a coupling agent to promote the adhesion of the primer coating to the optical base and / or scratch resistant coating. The same coupling agents, in the same amounts as for scratch-resistant coating compositions, can be used in coating compositions that provide impact resistance.

[0029] The coating composition imparting impact resistance may be applied to the lens base using any classical method, such as centrifugation, immersion, or flow coating.

[0030] The coating composition imparting impact resistance may simply be dried or optionally pre-crosslinked before the formed lens bases. Depending on the type of scratch resistant primer coating composition, thermal crosslinking, UV crosslinking or a combination of both methods can be used.

[0031] The thickness of the primer coating giving impact resistance after crosslinking is typically in the range of 0.05 to 30 μm, preferably 0.5 to 20 μm and more particularly 0.6 to 15 μm, and even better 0.6 to 5 μm.

[0032] Any known abrasion and / or scratch resistant coating compositions can be used to form the abrasion and / or scratch resistant coating. Thus, the abrasion and / or scratch resistant coating compositions may be UV and / or thermally curable compositions.

[0033] By definition, an abrasion and / or scratch resistant coating is a coating that improves the abrasion and / or scratch resistance of a finished optical article compared to the same optical article but without an abrasion and / or scratch resistant coating. Preferred coating compositions are (meth) acrylate based coatings. The term (meth) acrylate means albomethacrylate or acrylate.

EP1952183B1 [0034] The main component of the (meth) acrylate coating compositions may be selected from monofunctional (meth) acrylates and multifunctional (meth) acrylates such as difunctional (meth) acrylates; trifunctional (meth) acrylates; tetrafunctional (meth) acrylates; pentafunctional (meth) acrylates; hexafunctional (meth) acrylates.

[0035] Examples of monomers that can be used as the main components of (meth) acrylate coating compositions are:

· Monofunctional (meth) acrylates: allyl methacrylate, 2-ethoxyethyl acrylate, ethoxyethyl 2-methacrylate, caprolactone acrylate, isobornyl methacrylate, lauryl methacrylate, polypropylene glycol monomethacrylate.

· Difunctional (meth) acrylates: 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxylated bisphenol glycol diacrylate diacrylate, neopentyl glycol diacrylate, 1,4-butanediol dimethacrylate, tetraethylene glycol dimethacrylate, diethylene glycol diacrylate.

Trifunctional (meth) acrylates: trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate.

· Tetra- to hexafunctional (meth) acrylates: dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaacrylate esters.

[0036] Other preferred abrasion and / or scratch resistant coatings are those made by crosslinking the precursor composition containing epoxyalkoxysilanes or their hydrolyzate, optionally colloidal mineral fillers, and a crosslinking catalyst. Examples of such compositions are disclosed in US 4,211,823, WO 94/10230, US5,015,523, EP614957.

[0037] Particularly preferred abrasion and / or scratch resistant coating compositions based on epoxyalkoxysilane are compositions containing as the principal component epoxyalkoxysilane such as, for example, γ-glycidoxypropyl trimethoxysilane (GLYMO) and dialkyldialkoxysilane such as, for example, dimethyl diethoxysilane (DMD), silica a colloidal and catalytic amount of a crosslinking catalyst such as aluminum acetylacetonate or its hydrolyzate, and the remainder of the compositions are essentially the solvents typically used for formulating these compositions.

[0038] To improve the adhesion of the abrasion and / or scratch resistant coating to the primer coating that provides impact resistance, an effective amount of at least one coupling agent can be added to the abrasion and / or scratch resistant coating composition. A preferred coupling agent is a pre-condensed solution of epoxyalkoxysilane and unsaturated alkoxysilane, preferably containing a terminal ethylene double bond.

[0039] Examples of epoxyalkoxysilanes are GLYMO, γ-glycidoxypropyl-pentamethyldisiloxane, γ-glycidoxypropyl-methyl-diisopropenoxysilane, γ-glycidoxypropyl-methyl-diethoxysilane, γ-glycidoxy-propyl-dimethyl-ethoxysiloxysiloxy methylsilane. The preferred epoxyalkoxysilane is GLYMO.

[0040] The unsaturated alkoxysilane may be vinyl silane, allyl silane, acrylic silane or methacrylic silane.

[0041] Examples of vinyl silanes are vinyl tris (2-methoxyethoxy) silane, vinyl trisisobutoxysilane, vinyl tri-tert-butoxysilane, vinyl triphenoxysilane, vinyl trimethoxysilane, vinyl tri triis

EP1952183B1 propoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinylmethyldiethoxysilane, vinylmethyl diacetoxysilane, vinyl bis (trimethylsiloxy) silane and vinyl dimethoxyethoxysilane.

[0042] Examples of allylsilanes are allyltrimethoxysilane, allyltriethoxysilane and allylotris (trimethylsiloxy) silane.

[0043] Examples of acrylosilanes are 3-acryloxypropyltris (trimethylsiloxy) silane, 3-acryloxypropyltrimethoxysilane, acryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethylbis (trimethylsiloxy) silane, 3-acryloxypropyl dimethylmethoxysilane, N-3-hydroxy-ethoxy

[0044] Examples of methacrylosilanes are 3-methacryloxypropyltris (vinyl dimethoxysiloxy) silane, 3-methacryloxypropyltris (trimethylsiloxy) silane, 3-methacryloxypropyltris (methoxyethoxy) silane, 3-methacryloxy-propyltrimethoxysilane, 3-methacryloxy-methacryloxy methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyl dimethylmethoxysilane, 3-methacryloxypropyl dimethylethoxysilane, 3-methacryloxy-propenyl-trimethoxy-silane and 3-methacryloxypropylbis (trimethylsiloxy) methylsilane.

[0045] A preferred silane is acryloxypropyl trimethoxysilane.

[0046] Preferably, the amounts of epoxyalkoxysilane (s) and unsaturated alkoxysilane (s) used to form the coupling agent are such that the weight ratio:

weight of epoxyalkoxysilane

R = the weight of the unsaturated alkoxysilane satisfies the condition 0.8 <R <1.2.

[0047] The coupling agent preferably contains at least 50% by weight solid material of epoxyalkoxysilane (s) and unsaturated alkoxysilane (s), and more preferably at least 60% by weight. The coupling agent preferably contains less than 40% by weight of liquid water and / or organic solvent, more preferably less than 35% by weight.

[0048] The expression "weight of solid material from epoxyalkoxysilanes and unsaturated alkoxysilanes" means that the theoretical dry weight of these silanes is the calculated weight of the unit QkSiO (4-k) / 2, where Q is an organic group that has an epoxy or unsaturated group and QkSiO (4-k) / 2 comes from QkSiR'O (4-k), where Si-R 'reacts during hydrolysis to form SiOH.

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

R 'is preferably an alkoxy group such as OCH3.

[0049] The water and organic solvents mentioned above are derived from those which were initially added in the coupling agent composition and the water and alcohol resulting from the hydrolysis and condensation of alkoxysilanes present in the coupling agent composition. [0050] Preferred methods for producing the coupling agent include:

1) mixing alkoxysilanes

2) hydrolysis of alkoxysilanes, preferably by the addition of an acid such as hydrochloric acid

3) mixing the mixture

4) optional addition of an organic solvent

5) addition of one or more catalysts such as aluminum acetylacetonate

6) mixing (typical time: overnight).

[0051] Typically, the amount of coupling agent incorporated into the scratch-resistant coating composition is 0.1 to 15% by weight of the total weight of the composition, preferably 1 to 10% by weight.

[0052] The abrasion and / or scratch resistant coating composition may be applied to a primer coating providing impact resistance using any classical method, such as centrifugation, immersion, or flow coating.

[0053] The abrasion and / or scratch resistant coating composition may simply be dried or optionally pre-crosslinked prior to applying the subsequent anti-reflective coating. Depending on the type of abrasion and / or scratch resistant coating composition, thermal crosslinking, UV crosslinking or a combination of both methods can be used.

[0054] The thickness of the abrasion and / or scratch resistant coating after crosslinking is usually in the range from 1 to 15 μm, preferably from 2 to 6 μm, preferably from 3 to 5 microns.

[0055] If an anti-reflective coating is applied to the abrasion and / or scratch resistant coating, it is possible to subject the surface of the abrasion resistant and / or scratch coating to corona discharge or plasma-vacuum treatment to increase adhesion.

[0056] Anti-reflective coatings and methods for their preparation are well known in the art. Anti-reflective can be any layer or stack of layers that improves the anti-reflective properties of the finished optical article. The anti-reflective coating can be mono- or multilayer, and preferably consists of a monolayer or multilayer film of dielectric materials, such as SiO, SiO2, Si3N4, TiO2, ZrO2, Al2O3, MgF2 or Ta2O5, or mixtures thereof.

[0057] The anti-reflective coating can be applied in particular by vacuum deposition according to one of the following techniques:

1) - by evaporation, possibly supported by ion beam;

2) - by spraying using an ion beam,

3) - by cathodic sputtering; or

4) - by plasma-assisted chemical vapor deposition.

[0058] The anti-reflective coating can also be applied by applying liquid solutions, preferably by means of a coating process, preferably by means of a spincoating process.

[0059] In the case where the anti-reflective coating contains a single layer, its optical thickness must be λ / 4, where λ is a wavelength of 450 to 650 nm. Preferably, the anti-reflective coating is a multilayer film comprising three or more layers of dielectric material with alternatingly high low refractive indexes.

[0060] A preferred anti-reflective coating may comprise a pile of four layers formed by vapor deposition, for example a first SiO2 layer having an optical thickness of about 100 to 160 nm, a second ZrO2 layer having an optical thickness of about 120 to 190 nm, a third layer SiO2 having a thickness about 20 to 40 nm optical and a fourth ZrO2 layer having an optical thickness of about 35 to 75 nm.

[0061] According to the method of the invention, the outermost layer of the optical article to be coated with an anti-fouling coating must have been previously treated with energetic particles for a certain period of time, resulting in a physical attack on the surface and / or chemical modification. The liquid coating material to be deposited on the outermost layer of the optical article must also be

EP1952183B1 treated with energetic particles prior to the vacuum deposition step, according to the same or different energetic treatment.

[0062] By energetic particles is meant particles with energy in the range from 1 to 150 eV, preferably from 10 to 150 eV, and more preferably from 40 to 150 eV. Energy particles can be chemical particles, such as ions, radicals, or particles such as photons or electrons.

[0063] The treatment with energetic particles of the outermost layer of the optical article and / or the liquid coating solution can be carried out at any pressure, vacuum or atmospheric pressure. When it is conducted under vacuum, the pressure is generally lower than 70 Pa, preferably lower than 40 Pa, although a pressure higher than 10 Pa is preferred.

In order to avoid excessive manipulation of the materials, the coating material to be deposited according to the invention and the outermost layer of the optical article to be coated can be simultaneously treated with the same energetic particles, which means that they are treated in this same vacuum chamber under the same pressure. Indeed, the presence of the coating material in the vacuum chamber does not affect the surface treatment of the optical article.

[0065] The energy treatments in the present invention are first of all aimed at improving the adhesive ("bonding") properties between the anti-fouling top coat and the outermost layer of the optical article. Good adhesion requires strong interaction forces through chemical compatibility and / or chemical bonding. Treatments such as plasma can also assist in the formation of chemically active functional groups such as amino, carbonyl, hydroxyl and carboxyl groups, which improves adhesion in the area of ​​interaction. For example, the use of oxygen gas plasma can produce hydroxyl functional groups, and thus increase the wettability of the surface.

[0066] In this case, it is believed that treatment with energetic particles activates the surface of the outermost layer of the optical article by changing the chemical composition of several of the outermost molecular layers.

[0067] Without being bound by theory, the inventors speculate that the liquid coating material also undergoes chemical modifications during energy treatment, and thus becomes susceptible to sticking to the outermost layer of the optical article. However, the energy treatment should be selected so as not to seriously change the properties of the liquid coating material to be deposited, for example hydrophobic and / or oleophobic properties.

[0068] The energy treatment according to the present invention is also used to control the surface energy of the outermost layer of the optical article. It is preferred that the energy treatment gives the outermost layer of the optical article a surface energy of at least 60 mJ / m², preferably at least 72 mJ / m². The processing time, which depends on the type of optical article, can be varied to achieve such surface energy.

[0069] The energy treatment according to the present invention can also carry out surface cleaning, which is a safe and environmentally friendly alternative to traditional cleaning methods. For example, plasma-gas treatment can remove organic surface contaminants from the materials used. Active energy particles undergo chemical reactions with impurities, which results in their volatilization and removal from the vacuum chamber.

[0070] Finally, if the surface to be treated is of the polymeric type, the energy treatments according to the invention can produce a higher crosslinking density within

EP1952183B1 material, to a depth of several thousand angstroms. Surface crosslinking can increase certain performance such as hardness and chemical resistance.

[0071] Examples of treatments with energetic particles are, but are not limited to: vacuum plasma treatment, plasma treatment at atmospheric pressure, discharge plasma treatment, corona discharge treatment, ion beam bombardment, in particular with ionic (especially rare gases, oxygen, nitrogen, air) or mixtures thereof), or electron beam bombardment.

[0072] According to the invention, the preferred energetic particle treatment is plasma treatment, more preferably vacuum plasma treatment. Plasma can be defined as partially (low temperature plasma) or fully (high temperature plasma) ionized gas having approximately the same number of positively and negatively charged particles.

[0073] Plasma can be generated by subjecting a gas to a high voltage or high temperature arc (discharge). The source of electricity that will stimulate the gas and ionize the atoms and molecules can be DC or AC current, radio frequency or microwaves. The sources are connected to the electrodes between which the samples are placed.

[0074] Energy particles in gas plasma include ions, electrons, radicals, metastable particles and photons in the short-wave ultraviolet (UV) range. Materials in contact with gas plasma are bombarded with these energetic particles, and their energy is transferred from the plasma to these materials. These energy transfers are dispersed inside materials through various chemical and physical processes (functionalization, grafting, digestion, crosslinking, etc.), resulting in a unique type of modification. In the case of surface treatment, the properties of the material in its mass do not change.

[0075] A wide range of process parameters can be varied to affect the physical characteristics of the plasma used here and then affect the chemical composition of the surface obtained by plasma modification. These parameters are, for example, the power used for machining, the machining time and the working pressure. This wide range of parameters offers greater control over the plasma process than offered by most high energy radiation processes.

[0076] Practically, the machining time and power used for the machining required for the successful implementation of the method according to the invention can be easily determined by a person skilled in the art.

[0077] When both the outermost layer of the optical article and the liquid coating solution for the anti-fouling top coat have been energetically treated and put together in a vacuum chamber equipped with an evaporation device, a vaporization step can be performed.

[0078] An anti-fouling top coat is used here to improve the resistance to dirty stains of the finished optical article, in particular an abrasion and / or scratch resistant coating or an anti-reflective coating.

[0079] As is known in the art, the surface anti-fouling coating is a layer for which the stationary contact angle for deionized water is at least 75 °, preferably at least 90 °, and more preferably more than 100 °. The stationary contact angle is determined according to the liquid drop method in which a drop of water having a diameter of less than 2 mm is formed on the optical article and the contact angle is measured. It corresponds to the angle at which the surface of the water drop meets the surface of the optical article.

[0080] Anti-fouling top coats, preferably used in this invention are those that reduce the surface energy of the optical article to less than 14 mJ / m². The invention is particularly useful when anti-fouling top coatings have a surface energy of less than 13 mJ / m²and even better less than 12 mJ / m².

EP1952183B1 [0081] The surface energy values ​​indicated above are calculated according to the Owens-Wendt method described in the following document: Owens, DK; Wendt, RG "Estimation of the surface force energy of polymers", J. Appl. Polym. Sci. 1969, 51, 1741-1747.

[0082] The anti-fouling top coat of the invention is preferably organic. By organic nature is meant a layer which at least 40% by weight, preferably at least 50% by weight, based on the total weight of the coating layer, consists of organic materials.

[0083] A preferred anti-fouling top coat is a hydrophobic and / or oleophobic top coat, and more preferably an anti-fouling top coat made of a liquid coating material containing at least one fluorinated compound.

[0084] Most often, the hydrophobic and / or oleophobic surface coatings contain silane-based compounds having fluorinated groups, in particular perfluorocarbon or perfluoropolyether groups. For example, silazane, polysilazane or silicone compounds containing one or more fluorine-containing groups such as those mentioned above should be mentioned. Such compounds are widely disclosed in the art, for example in US Patent publications 4410563, EP 0203730, EP 749021, EP 844265 and EP 933377.

[0085] A known method of forming the anti-fouling top coat is to deposit, on the anti-reflective coat, compounds having fluorinated groups and Si-R groups, where R is a -OH group or its precursor, such as -Cl, -NH2, -NH- or - O-alkyl, preferably alkoxy. Such compounds can carry out polymerization and / or crosslinking reactions with protruding reactive groups on the surface of the anti-reflective coating, directly or after hydrolysis.

[0086] Preferred fluorinated compounds are silanes and silazanes having at least one group selected from fluorinated hydrocarbons, perfluorocarbons, fluorinated polyethers such as F3C- (OC3F6) 24-O- (CF2) 2- (CH2) 2-O-CH2- Si (OCH3) 3 and perfluoropolyethers, in particular perfluoropolyethers.

[0087] Among the fluorosilanes that may be mentioned are compounds having the formulas:

OR

<img file="PL1952183T3_D0001.tif" />

OR where n = 5, 7, 9 or 11 and R is an alkyl group, typically a C1-C10 alkyl group such as methyl, ethyl propyl;

CF3CH2CH2SiCl3;

<img file="PL1952183T3_D0002.tif" />

EP1952183B1

<img file="PL1952183T3_D0003.tif" />

where n '= 7 or 9 aR is as defined above.

[0088] Compositions containing fluorinated compounds, also useful for the preparation of hydrophobic and / or oleophobic top coatings, are disclosed in US 6,183,872.

The silicon-containing organic fluoropolymer of US 6,183,872 is represented by the following general formula and has a number average molecular weight from 5 * 10² up to 1 * 10⁵.

<img file="PL1952183T3_D0004.tif" />

where RF represents a perfluoroalkyl group, Z represents a fluorine atom or trifluoromethyl group, a, b, c, d and e independently represent 0 or an integer equal to or greater than 1, provided that a + b + c + d + e is not less than 1 and the order of the repeat units in parentheses with subscripts a, b, c, and d appearing in the above formula is not limited to the order shown; Y represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; X represents a hydrogen, bromine or iodine atom; R¹ represents a hydroxyl group or a hydrolyzable substituent group; R²represents a hydrogen atom or a monovalent hydrocarbon group; And represents 0, or2; m represents 1, 2 or 3; and n "represents an integer equal to 1 or higher, preferably equal to 2 or higher.

[0089] Other preferred compositions for forming a hydrophobic and / or oleophobic coating are compositions containing compounds containing fluorinated polyether groups, in particular perfluoropolyether groups. A particularly preferred class of compositions containing fluorinated polyether groups is disclosed in US 6,277,485. The anti-fouling top coatings of US 6,277,485 are at least partially crosslinked coatings containing a fluorinated siloxane prepared by applying a coating composition (typically in the form of a solution) containing at least one fluorinated silane having the following formula:

<img file="PL1952183T3_D0005.tif" />

EP1952183B1 where RF is a monovalent or divalent fluorinated polyether group, R¹ is a divalent alkylene group; an arylene group, or combinations thereof, optionally containing one or more heteroatoms or functional groups, and optionally substituted with halogen atoms, and preferably containing 2 to 16 carbon atoms; R² is a lower alkyl group (i.e., a C1-C4 alkyl group); Y is a halogen atom, a lower alkoxy group (i.e. a C1-C4 alkoxy group, preferably a methoxy or ethoxy group), or a lower acyloxy group (i.e. a -OC (O) R group³where R³ is a C1-C4 alkyl group); x is 0 or 1; ay is 1 (RF is monovalent) or 2 (RF is bivalent). Suitable compounds typically have a molecular weight (number average) of at least about 1000. Preferably, Y is a lower group and RF is a fluorinated polyether group.

[0090] Commercial compositions for the production of anti-fouling top coatings are compositions KY130 and KP 801 M, sold by the company Shin-Etsu Chemical, and the composition OPTOOL DSX (fluorine resin, containing perfluoropropylene moieties), sold by the company Daikin Industries. OPTOOL DSX is the most preferred coating material for anti-fouling top coatings.

[0091] The liquid coating material for forming the anti-fouling top coat according to the invention, generally referred to as "liquid coating material", may contain one or more of the abovementioned compounds. Preferably, such compounds or mixtures of compounds are liquid or can be converted into liquid by heating, thus being in a state suitable for evaporation. Such a liquid coating material is applied to the outermost layer of the gas phase optical article by means of an evaporation device.

[0092] It is preferred to use the vacuum deposition method because the anti-reflective layers are generally deposited by vapor deposition in the vacuum chambers, and it is desirable to deposit the anti-fouling layer by the same method, which allows all operations to be carried out sequentially, without overly manipulating the lenses between stages.

[0093] Various vaporization devices may be used in the method of the invention, such as devices based on an ion or electron beam heating method, devices based on a high frequency heating method, devices based on an optical heating method (e.g. devices containing a tungsten lamp), devices based on the Joule effect or resistance heating devices, and more generally any heating device that provides enough heat to evaporate the liquid coating material. These devices are well known in the art. In a preferred embodiment, the vaporization device is an electron gun or device based on the Joule effect, most preferably a device based on the Joule effect.

[0094] In one embodiment of the invention, said device based on the Joule effect is an electrical circuit connected to a steel wool element on which a liquid coating material is deposited on the anti-fouling top coat. When electric current (AC or DC) passes through steel wool, the liquid coating material is evaporated. The power and time required to evaporate the liquid coating material depends on the type of liquid coating material used. When a steel wool element is used, the required power and time also depend on the type of steel wool element.

[0095] In another embodiment of the invention, the liquid coating material is poured into a capsule, such as a copper capsule, which is in turn placed in a Joule effect carrier, such as tantalum or molybdenum crucible, which can be heated at a temperature of about 400 ° C to allow evaporation . Alternatively, the liquid coating material may be heated by an electron beam directed towards the carrier.

EP1952183B1 [0096] Evaporation must be started after treatment of the outermost layer of the optical article with energetic particles and after treatment of the liquid coating material with energetic particles. If the vacuum evaporation and treatment with energetic particles of said outermost layer and said liquid coating material starts at the same time in the same vacuum chamber, adhesion problems may be encountered.

[0097] If the liquid coating material is vacuum evaporated without prior treatment with energetic particles, adhesion problems may be encountered, especially if the evaporation is carried out at a pressure higher than 10 Pa.

[0098] When both energy treatments are carried out in the same vacuum chamber, the evaporation step can be started immediately after such treatments. In a preferred embodiment, no energetic particle treatment is performed during the vacuum evaporation step, which means that such treatment is stopped when it is reached, for example after satisfactory surface energy has been obtained, and then evaporation can be started. However, the treatment with energetic particles of the outermost layer of the optical article and / or the liquid coating solution can be continued throughout the entire vapor deposition stage or only part thereof without changing the deposition process.

[0099] It is also possible to apply additional energetic treatments during the vacuum evaporation step. Ion bombardment directed toward the surface of the optical article may be referred to to improve mechanical properties, in particular to compact the deposited layer. This process is typical and known as "ion assisted deposition" or IAD.

[0100] Vacuum vaporization is generally carried out here at a pressure lower than 70 Pa, preferably lower than 40 Pa and more preferably lower than 30 Pa. In one embodiment of the invention, the evaporation is carried out at a pressure higher than 10 Pa, which does not lead to problems with adhesion. This means that the pressure requirements of the method according to the invention are particularly unrestricted compared to the pressure requirements of the prior art methods. Consequently, vacuum chambers that are not capable of providing advanced vacuum can now be used for such anti-fouling coating method. Of course, the method of the invention can also be carried out at a lower pressure, for example at a pressure in the range of 10^-3 up to 10^-1 Pa. The operating pressure may be as low as is technically allowed for the vacuum chamber used.

[0101] The process according to the invention is carried out more easily if the same pressure is applied during the energy treatment and vacuum evaporation steps.

[0102] In practice, since energy treatments do not have to be carried out by vacuum, when this feature is a requirement for the evaporation stage, the vacuum must be withdrawn from the vacuum chamber so that the evaporation can begin, preferably at the end of the energy treatments, unless the energy treatments were carried out under a vacuum suitable for the next evaporation stage, which can be carried out without pressure modification.

[0103] It is worth noting that when energetic treatments are carried out under vacuum, the vacuum can be released and the vacuum chamber open at the end of such treatments for a certain period of time before performing the vacuum evaporation step, without consequences for the adhesion of the anti-fouling top coat. Consequently, the energetic treatments of the surface of the optical article and the liquid coating material need not be carried out simultaneously in the same vacuum chamber.

[0104] The evaporation step of the liquid coating material results in the deposition of the evaporated coating material on the treated outermost layer of the optical article. When the desired thickness is achieved, evaporation of the coating material stops. In general, anti-fouling thus obtained

The surface coating has a physical thickness lower than 30 nm, preferably in the range from 1 to 20 nm, more preferably in the range from 1 to 10 nm, and even better from 1 to 5 nm. The embedded thickness check can be carried out using a quartz balance.

[0105] As previously indicated, optical articles that can be treated by the method of the invention have two main sides, at least one of which is coated with the outermost layer. The method of the invention is preferably used for the production of ophthalmic lenses coated on their concave side (back side). If desired, the coating can also be made only on the convex main surface or on both sides.

[0106] The lenses to be treated according to the method of the invention are lens blanks (eyepieces), which can be semi-finished or finished lenses. Finished lenses are lenses obtained in their final shape, having both of their main face sides covered with a surface or cast to the required geometry. Semi-finished lenses are lenses that, after molding, have only one of their main face sides covered with the surface or cast to the required geometry, and in which preferably one side of the lens, preferably the front side, has previously been treated with a suitable coating (anti-reflective, hardness coating) , a primer coating for impact resistance, etc.). Its other facing side, preferably the back facing side, must then be coated and surface treated as required. The lenses may also be polarized or photochromic.

[0107] Successful implemented methods of the invention can be easily checked, for example by measuring the contact angle on finished optical articles, which value must be as defined above. The contact angle should not decrease after the finished optical article has been subjected to hydrolytic treatment.

As a result of the anti-fouling layer of the invention being deposited on the outermost layer of the optical article, a finished article is obtained having two main facing sides, at least one of which has a coating layer coated with a top coating having anti-fouling properties and adhering to the surface of said coating layer. In a preferred embodiment, both main faces of the optical article are coated with an anti-fouling top coat.

[0109] The method of the invention may be carried out in a vacuum treatment machine as described hereinafter.

[0110] The pump of such a machine is a normal pump, used for medium vacuum. The pump comes from Hanning Elektro-werke. This is the VDE 0530 model. These pumps are used when a medium vacuum is needed.

[0111] The method of the invention may be carried out using the machine described above as follows.

[0112] The vacuum chamber is a cylinder in which the cylinder front is an opening and the rear is where the vacuum is drawn. The lenses are placed flat in the chamber. Machining is carried out simultaneously on both sides. The anti-fouling coating is placed from the front of the cylinder.

[0113] The present invention will now be described in more detail with reference to the following examples. These examples are provided to illustrate the invention only and should not be construed as limiting the scope and spirit of the present invention.

Examples

Manufacture of lenses with the outermost abrasion resistant layer [0114] Organic glass lenses having an abrasion resistant coating were produced.

EP1952183B1 [0115] The coatings were deposited on bases, which are: -2.00 polycarbonate ophthalmic lenses, round with a diameter of 65 mm, having on both sides an abrasion resistant coating. The lenses were industrial lenses sold under the name Airwear ™.

[0116] A PDG-32G lens processing machine from Harrick Plasma with a VDE 0530 pump from Hanning Elektro-Werke was used. The evaporation device of the machine consisted of an elongated element of steel wool connected to both sides with an electric circuit.

Example 1 [0117] The purpose of this experiment is to evaluate the plasma power and processing time required to treat the anti-fouling liquid coating material so as to successfully deposit the top anti-fouling top coat on the abrasion resistant coating of already energetically treated ophthalmic lenses.

[0118] The energetic particle treatment was a vacuum plasma treatment. Plasma PDC-32G plasma was used. A current of 1.2 A was used for evaporation (treatment time: 5 min).

[0119] The anti-soiling liquid coating material was the OPTOOL DSX coating solution, sold by the company DAIKIN Industries.

[0120] Contact angles were measured on the finished optical articles according to the liquid drop method by depositing a distilled water droplet with a diameter less than 2 mm on the coated surface of said optical article.

[0121] Lenses as defined above were placed in a vacuum chamber containing an evaporation device without OPTOOL DSX mounted on a steel wool element. The chamber was sealed and vacuum removed (200 mTorr, «27 Pa). Plasma treatment was started after obtaining the proper vacuum. At the end of the treatment time (20 s, 720 V DC, 25 mA DC, 18 W) the plasma was stopped, the vacuum removed and the vacuum chamber opened.

[0122] Next, 1 ml of OPTOOL DSX was deposited on the steel wool element contained in the evaporation apparatus. Then the vacuum was again drawn (200 mTorr, 2727 Pa) and plasma treatment was again started at low, medium or high power (see table below) for 10, 20 or 30 seconds.

[0123] The following plasma powers were tested:

<td>Low power</td><td>680 V DC</td><td>10 mA DC</td><td>6.8 watts</td>

<td>Average power</td><td>700 V DC</td><td>15 mA DC</td><td>10.5 watts</td>

<td>High power</td><td>720 V DC</td><td>25 mA DC</td><td>18 watts</td>

[0124] The plasma was then stopped and vacuum evaporation started by switching on the current for a period of 5 minutes. The current was stopped and the vacuum was released.

[0125] Contact angles measured for finished optical articles are summarized in the following table:

EP1952183B1

<td rowspan="2">Processing time with liquid coating material (s)</td><td colspan="3">Contact angle with deionized water</td>

<td>Low power</td><td>Average power</td><td>High power</td>

<td> 10</td><td> 59,19°</td><td> 98,92°</td><td> 103,75°</td>

<td> 20</td><td> 56,12°</td><td> 100,20°</td><td> 104,95°</td>

<td> 30</td><td> 97,18°</td><td> 100,85°</td><td> 100,99°</td>

[0126] Better results were obtained with a processing time of 20 seconds and high plasma power (18 W, 720 V DC, 25 mA DC). Such settings were used in examples 2-6.

Examples 2-6 [0127] Energetic particle treatment was a vacuum plasma treatment that allowed the simultaneous treatment of the outermost layer of an optical article and a liquid coating material. Plasma cleaners PDC-32G was used as the plasma with 18 W plasma power (720 V DC, 25 mA DC) and a processing time of 20 seconds.

[0128] A current of 1.2 A was used for evaporation (treatment time: 5 min).

[0129] The liquid coating material was the OPTOOL DSX coating solution, sold by DAIKIN Industries or the KP 801 M coating solution, sold by Shin-Etsu Chemical.

Example 2 [0130] Lenses with an abrasion resistant coating as described above were placed in a vacuum chamber containing an evaporation device with 1 ml OPTOOL DSX mounted on a steel wool element. The chamber was closed and the vacuum removed (200 mTorr, 2727 Pa). Plasma treatment was started after obtaining the proper vacuum. Plasma treatment was carried out simultaneously on the surface of abrasion resistant coating and a steel wool element on which OPTOOL DSX was mounted. At the end of the treatment time (20 s after the plasma was switched on in the chamber) the plasma was turned off and vacuum evaporation and deposition of OPTOOL DSX on the surface of the abrasion resistant coating started by turning on the current for 5 minutes. The electricity was turned off and the vacuum removed.

Example 3 [0131] The same procedure was carried out as in Example 2, except that no current was turned on in the evaporation device. Instead, the vacuum was left for 5 minutes.

Example 4 [0132] The same procedure was carried out as in Example 2, except that after the plasma was stopped, the vacuum was released and the vacuum chamber was opened. Then vacuum was again drawn (200 mtorr, «27 Pa) and evaporation was carried out as in Example 2.

Example 5 [0133] The lenses (prepared as described above) were placed in a vacuum chamber containing an evaporation device without OPTOOL DSX mounted on a steel wool element. The chamber was sealed and vacuum removed (200 mTorr, «27 Pa). Plasma treatment was started after obtaining the correct pressure. At the end of the treatment time (20 s after switching on the plasma in the chamber) the plasma power was turned off, the vacuum was removed and the chamber was opened. imprisoned

EP1952183B1 ml OPTOOL DSX on a steel wool element placed in an evaporation device.

Then the vacuum was again drawn (200 mTorr, ,27 Pa) and the evaporation started by switching on the current for 5 minutes. The electricity was turned off and the vacuum removed.

Example 6 [0134] The same procedure as in Example 2 was carried out using KP 801 M instead of OPTOOL DSX.

[0135] Contact angles measured for optical articles manufactured according to the procedures of Examples 2-6 are given in the table below:

<td></td><td>Example 2</td><td>Example 3 (comparative)</td><td>Example 4</td><td>Example 5 (comparative)</td><td>Example 6</td>

<td>Contact angle with deionized water</td><td> 105°</td><td> 39°</td><td> 103°</td><td> 50°</td><td> 95°</td>

[0136] Examples 2, 4 and 6 are examples of coating methods according to the invention. The contact angles obtained show that the deposition of the anti-fouling top coat on the outermost surface of the optical article was successful. The resulting lenses showed excellent cleanability after soiling.

[0137] As expected, Example 3 shows that an electric current is needed for the transition to evaporation. Example 4 shows that the opening of the plasma chamber at the end of the plasma treatment has no effect on the subsequent vacuum evaporation step because adhesion of the anti-fouling top coat is still achieved. In light of Example 4, Example 5 shows that if the energetic treatment of the liquid coating material is omitted, deposition of the anti-fouling top coat is unsuccessful.

[0138] Although preferred embodiments of this invention have been disclosed for illustrative purposes, it will be apparent to those skilled in the art that various modifications, additions and substitutions are possible without departing from the scope and spirit of the invention disclosed in the accompanying claims.