Patent Application
20210190995
The present invention relates generally to the field of optical lens coatings. More specifically, the present invention relates to the field of antifog coating for optical lenses.
Ophthalmic lenses are commonly coated with one or more functional coatings in order to increase at mechanical durability of the lens, optical performance of the lens and the like. Some commonly used coatings are, impact-resistant coating (impact-resistant primer), an abrasion- and/or scratch-resistant coating (hard coat), and an anti-fouling top coating. Other optional coatings include: a polarized coating, a photochromic or a dyeing coating and an anti-reflection (AR) coating. AR is one of the most commonly used coatings and is defined as a coating which improves the anti-reflective properties of an optical article when deposited at any of its surfaces. AR coatings can reduce reflection of light at the interface article-air over a relatively wide band of the visible spectrum.
An additional desired coating is the antifog coating. Antifog properties on the back and front surfaces of ophthalmic lenses in spectacles prevent condensation of water in the form of tiny droplets on the surface eyeglass lenses when the lenses are significantly cooler than the surrounding air temperature. This is commonly referred to as misting or fogging. This effect is common, for example, when corning inside from the cold. Lenses that minimize the fog are advantageous since misting of lenses impairs vision, is not aesthetic, and can cause fouling of the surface of the lenses. Preventing fog in lenses can be critical for vocations such as first responders in emergency situations, in military uses, for athletes, and workers in extreme environment conditions and the like.
The Antifog effect can be created by adjusting certain surface properties of the lens while not degrading any of the other desirable properties required of ophthalmic lenses, such as, clarity, durability, scratch resistance and the like. A preferred antifog coating will have long-lasting effect on the ophthalmic lenses. The current long-lasting solutions include forming long lasting hydrophilic coating that has low wetting/contact angle (i.e. <10 degrees) that causes the moisture from the air to spread in an even film over the surface of the lens without forming droplets.
Known in the art antifog coatings include micron size layer composed of a polymer matrix (e.g., polyurethane (PUR)) reinforced with different nanoparticles (e.g., silica-based nanoparticles), Some examples for commercially used antifog coatings include: Visguard (FSI), SAF-100 (NEI), Scotchguard (3M) and Akita SpektraShield™.
However, these known in the art antifog coatings are designed in a way that leads to a surface that is vulnerable to abrasion. Since part of the hulk polymer matrix of these antifog coatings serves as a deposit for migratory chemicals used to increase the wetting of the surface, the bulk mechanical properties and robustness of the polymer coating are compromised to some extent. These properties tend to lead to shorter lifetime due to low abrasion resistance and surface fouling, disregarding the performance of the antifogging properties.
Some attempts were made to improve the durably and cleanability of the hydrophilic coating by adding a hydrophobic layer on top of the hydrophilic coating, by dip coating, to form an antifog coating. The dip coating method results in forming the antifog coating on both the back and front sides of the lens. Accordingly, applying an additional coating, such as AR coating, on the front side of the lens is challenging. The AR coating process generates a “haze” over the accepted norm in the industry <1% since the evaporated materials interact with the antifog polymer. Furthermore, the chemical bonding formed between the hydrophilic coating and the hydrophobic layer, formed in dip coating, is limited due to (a) the nature of the chemical formulation utilized for a solvent based coating to avoid agglomeration of the active component (b) steric interference with the delivery agent, i.e. solvent chemistry, which has to be removed from the surface prior to chemical bonding of the active component.
Accordingly, there is a need for an improved antifog coating which has both good optical antifogging performance and mechanical durability. Such a coating may be applied only to one side to the lens, leaving the other side to be coated by any of the other coating disclosed herein above.
Some aspects of the invention may be related to an antifog coating having improved properties and methods of forming such a coating. In some embodiments, the improvement of the overall performance of the permanent polymer matrix in the hydrophilic coating may include surface attachment of hydrophobic moieties allowing access to the active antifogging reservoir while repelling unwanted surface contamination and improving overall abrasion performance. A method according to some embodiments of the invention may allow coating only one side of the lens (e.g., the back side) with an antifog coating while leaving the other side (e.g., the front side) to be coated by any additional coating, such as AR coating, hard coating and the like.
A lens with an antifog coating according to some embodiments of the invention may include: a lens composed of a transparent optical material; a hydrophilic layer applied only on a first surface of the lens; and a hydrophobic nanolayer applied on top of the hydrophilic layer, In some embodiments, the hydrophobic nanolayer may be applied only on top of the hydrophilic layer applied on the first surface of the lens.
In some embodiments, the lens may further include a transparent coating applied on a second surface of the lens, the transparent coating may include at least one of: a hard coating and an antireflective coating, in some embodiments, the lens may further include a hydrophobic nanolayer applied also on top of the transparent coating.
In some embodiments, the hydrophobic nanolayer may include at least one of: fluorinated organic silicon, amino-modified silicon, mercapto-modified silicon and hydrocarbons. In some embodiments, the hydrophilic layer may include a polyurethane matrix and silica-based nanoparticles. In some embodiments, the silica-based nanoparticles are polyhedral oligomeric silsesquioxanes. In some embodiments, the hydrophilic layer has a thickness of 4-15 μm. In some embodiments, the hydrophobic nanolayer has a thickness of 2-15 nm. In some embodiments, the first surface is a back surface of the lens and the second surface is a front surface of the lens, when the lens is assembled in an optical device.
A method of forming an antifog coating of a lens according to some embodiments of the invention may include: applying a first hydrophilic layer, on a first surface of the lens; applying a plasma treatment to a free surface of the first hydrophilic layer; and applying a hydrophobic nanolayer on top of the plasma treated free surface of the first hydrophilic layer.
In some embodiments, the hydrophobic nanolayer may be composed of at least one of: fluorinated organic silicon, amino-modified silicon, mercapto-modified silicon and hydrocarbons. In some embodiments, the hydrophilic layer may include a polyurethane matrix. In some embodiments, applying the first hydrophilic layer is by spin coating. In some embodiments, the method may further include applying a second hydrophilic layer, on a second surface of the lens. In some embodiments, applying the first hydrophilic layer and the second hydrophilic layer is by dip coating. In some embodiments, the method may farther include applying a plasma treatment to a free surface of the second hydrophilic layer and applying a hydrophobic nanolayer on top of the plasma treated free surface of the second hydrophilic layer.
In some embodiments, the applied plasma treatment is at least one of: low pressure oxygen plasma treatment, a corona treatment and an atmospheric plasma oxidation treatment. In some embodiments, the hydrophobic nanolayer is applied by one of: physical vapor deposition, chemical vapor deposition and plasma assisted ionization. In some embodiments, the physical vapor deposition is conducted at: a pressure of 0.0015-0.003 Pa. In some embodiments, the plasma treatment is provided: at a pressure of no more than 3 Torr, for 1-5 minutes and the plasma is provided at capacity of 2-10 standard cubic centimeters per minute (seem) and a power of up to 400 W at 50 KHz.
In some embodiments, the method may further include edging the coated lens at least 30 minutes after the application of the hydrophobic nanolayer. In some embodiments, the method may farther include curing the first hydrophilic layer prior to the application of the plasma treatment. In some embodiments, the curing is conducted by one of: ultraviolet (UV) curing and thermal curing.
In some embodiments, the method may farther include applying an additional transparent coating on a second surface of the lens. In some embodiments, the transparent coating may include at least one of: a hard coating and an antireflective coating. In some embodiments, the method may further include applying a hydrophobic nanolayer on top of the transparent coating.
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components, have not been described in detail so as not to obscure the invention. Some features or elements described with respect to one embodiment may be combined with features or elements described with respect to other embodiments. For the sake of clarity, discussion of same or similar features or elements may not be repeated.
Some aspects of the invention may be related to an antifog coating having an improved performance and methods of forming such a coating. Such a coating may include a combination of a hydrophilic layer applied only on at least one surface of the lens and a hydrophobic nanolayer applied on top of the hydrophilic layer. Applying the antifog coating only on one side (e.g., the back side) of the lens may enable coating the the other (e.g., front side) of the lens with a different coating. Therefore, a lens according to embodiments of the invention may include an improved antifog coating on the back side of the lens and, for example, AR coating and/or hard coating on the front side of the lens, providing each side of the lens the specific required properties.
In some embodiments, the hydrophobic nanolayer may be applied by a combination of plasma treatment (e.g., low temperature low pressure oxygen plasma treatment) and evaporation (e.g., physical vapor deposition, chemical vapor deposition and plasma assisted ionization).
A hydrophilic layer according to sonic embodiments of the invention may include a polymeric matrix, for example, a commercial blend of a PUR and polysiloxane bridges. The formulation may further include surfactants in an encapsulated form. The surfactants may be fixated and homogenously distributed in the polymeric matrix by thermal curing. The matrix may be designed to enable the migration of surfactants to the surface based on the surface surfactant concentration (i.e., le Chatelier's principle). In some embodiments, the microstructure of the hydrophilic layer may include nanoparticles, for example, Polyhedral Oligomeric Silsesquioxane (POSS), embedded in a polymeric matrix having a PUR backbone. POSS are nanostructured silica-based chemicals. In some embodiments, the application of the hydrophobic nanolayer may increase the durability of the coating, covalent bonding is formed between at least one component of the hydrophilic layer and the hydrophobic layer. In some embodiments, in order to ensure the formation of the covalent bonding, a novel method was invented. Accordingly, the POSS particles embedded in the PUR matrix may form covalent linking of a siloxane based hydrophobic moieties directly with the polymeric matrix.
Reference is now made to
A lens 10 may be any lens, for example, an ophthalmic lens. The ophthalmic lens substrate is available in a vast variety of lens materials, e.g.: CR-39, Trivex, 1.56, SuperLite 1.60, SuperLite 1.67, Polycarbonate, and SuperLite 1.74, etc.
In some embodiments, hydrophilic layer 12 may include any antifog coating known in the art (e.g., any long-lasting commercial antifog coating, as disclosed herein above). For example, hydrophilic layer 12 may include a polyurethane matrix and silica-based nanoparticles (e.g., POSS).
In some embodiments, a second hydrophilic layer may also be applied on a second surface of the lens. In some embodiments, applying the first hydrophilic layer and the second hydrophilic layer is by dip coating. In some embodiments, the final thickness of the first hydrophilic layer and/or the second hydrophilic layer may be 4-15 μm.
In some embodiments, the first and/or second hydrophilic layers may be cured, using any known method, for example, ultraviolet (UV) curing, thermal curing and the like.
In step 120, a plasma treatment may be applied/provided to a free surface of the first hydrophilic layer. As used herein, a free surface of a layer is a surface that is not attached to a substance or another coating layer, and not yet coated with an additional layer. In some embodiments, the plasma treatment may be applied/provided also to a free surface of the second hydrophilic layer. In some embodiments, the plasma treatment may activate the surface of the hydrophilic layer. For example, a plasma treatment 14 (illustrated in
In step 130, a hydrophobic nanolayer may be applied on top of the plasma treated free surface of the first hydrophilic layer. In some embodiments, a hydrophobic nanolayer may also be applied on top of the plasma treated free surface of the second hydrophilic layer, In some embodiments, the hydrophobic nanolayer may be composed of at least one of: fluorinated organic silicon, amino-modified silicon, mercapto-modified silicon, hydrocarbons and the like. For example, a hydrophobic nanolayer 16 (illustrated in
In some embodiments, the coated lens may be edged at least 30 minutes after the application of the hydrophobic nanolayer(s).
In some embodiments, the method may further include applying an additional transparent coating on the second surface of the lens, either instead or in addition to the second hydrophilic layer. In some embodiments, the additional transparent coating can be any transparent coating known in the art of lens coating, for example, a hard coating and an antireflective coating. In some embodiments, a hydrophobic nanolayer may be applied on top of the transparent coating, according to any one of the methods disclosed herein above.
Reference is now made to
In some embodiments, hydrophilic layer 232 may include any hydrophilic coating known in the art, for example, the commercial coatings: Visguard (FSI), SAF-100 (NEI), Scotchguard (3M), Akita SpektraShield™ and the like. In some embodiments, hydrophilic layer 232 may include PUR matrix and silica-based nanoparticles. In some embodiments, the silica-based nanoparticles are Polyhedral Oligomeric Silsesquioxanes embedded in the PUR matrix. In some embodiments, the thickness of hydrophilic layer 232 may be 2-30 μm, for example, 4-15 μm.
In some embodiments, hydrophobic nanolayer 234 may include at least one of: fluorinated organic silicon, amino-modified silicon, mercapto-modified silicon and hydrocarbons. In some embodiments, the siloxane functionality of hydrophobic nanolayer 234 forms covalent bonds with the silica-based nanoparticles of hydrophilic layer 232, after the exposure of the silica-based nanoparticles during a plasma treatment, as disclosed herein above in step 120 of the method of
In some embodiments, an additional transparent coating may be applied on second surface 214, as illustrated and discussed in
In some embodiments, lens 300 may further include an additional transparent coating 320 applied on a second surface 314 of lens 310. In some embodiments, transparent coating 320 may include at least one of: a hard coating 322 and an anti-reflection coating 324. In some embodiments, transparent coating 320 may further include at least one of: a hydrophobic nanolayer 326 applied on top of anti-reflection coating 324. In some embodiments, a grip coating 328 may be applied on top of anti-reflection coating 324 or hydrophobic nanolayer 326 to protect lens 300 during gripping in the manufacturing process. In some embodiments, hard coating 322 and antireflecting coating 324 may include any suitable corresponding coating known in the art.
In some embodiments, first surfaces 212 and 312 may be a back surface of corresponding lenses 200 and 300 and second surfaces 214 and 314 may be a front surface of corresponding lenses 200 and 300 when lenses 200 and 300 are assembled in an optical device (e.g., glasses).
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Various embodiments have been presented. Each of these embodiments may of course include features from other embodiments presented, and embodiments not specifically described may include various features described herein.
