Zwitterion-doped hydrogels and anti-fog coatings containing same - Patent Application 20070229633

Abstract

Disclosed is an anti-fog material comprising a zwitterion-doped hydrogel composed of charged monomers, at least a portion of which comprises a zwitterionic monomer, a non-charged hydrophilic monomer, and at least one crosslinker. Also disclosed is a transparent, removable article comprising a composition for forming a hydrogel and an anti-fog material. The article, which can be in the form of a film or decal, can comprise an active layer adhered to a backing layer, the active layer comprising the anti-fog material described herein. Also disclosed is a method of applying the transparent, removable article to a surface of a substrate to make the surface less prone to fog.

Description

[Technical field]

[0001]

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 240,629, filed September 3, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002]

[0002] The present disclosure relates generally to anti-fog coatings and methods of making the same. Embodiments of the present disclosure also relate to compositions used to make such coatings, as well as films and decals comprising such compositions that can be applied to desired substrates that benefit from an optically clear anti-fog coating, such as automobile windshields, camera lenses, and freezer windows. [Background technology]

[0003]

[0003] Anti-fog coatings are commonly used to keep glass and other transparent substrates from fogging due to condensation. A fogging environment occurs when the temperature of a surface is lower than the dew point of the surroundings, causing water vapor to condense on the surface and form water droplets. The size and shape of these droplets can cause light scattering and reduce the optical transparency through the surface. Some prior inventions have focused on applying hydrophobic coatings, such as silicone, to the substrate. These materials may work for a short period of time, but can be overwhelmed by a fogging environment, resulting in many droplet nuclei forming on the surface. A more common strategy is to use a hydrophilic coating, which allows the water droplets to have a low contact angle with the coated substrate, thereby forming a transparent flat sheet of water.

[0004]

[0004] Hydrophilic coatings face a trade-off between effectiveness and durability. In cloudy environments where the surface temperature is lower than the ambient dew point, hydrophilic coatings remain transparent by interacting well with liquid water, resulting in a low contact angle and liquid water forming a flat film across the coating. However, the strong interaction of this coating with liquid water may make the coating easily wash off or prone to swelling and damage in the presence of liquid water or water vapor. Conversely, more mechanically durable coatings incorporate stronger intermolecular bonds within the coating, such as chemical crosslinks or hydrophobic interactions, which may reduce the hydrophilicity of the coating and reduce performance.

[0005]

[0005] Many hydrophilic coatings are "hydrogels" that swell when exposed to liquid water or water vapor. These gels can be adversely affected by several factors. The interaction of hydrogels with water molecules is known to be highly dependent on the exact environmental conditions; changing the temperature, pH, or salt concentration can change the strength of the gel's interaction with molecular water, thus affecting the degree of swelling by several orders of magnitude. As a result, both the mechanical and anti-fog properties of coatings made from these materials are often unreliable for many applications. In addition to these unpredictable properties, certain molecular groups that give rise to the hydrophilic nature of the gels are known to have poor mechanical properties. Many common anti-fog coatings require a significant portion of the material to consist of these active groups, which must therefore sacrifice the mechanical durability of the coating.

[0006] The disclosed anti-fog zwitterion-doped hydrogel compositions are directed to overcoming one or more of the problems discussed above and / or other problems of the prior art. In particular, the compositions disclosed herein have high resistance to fogging. In addition, when the compositions are made into coatings, they are mechanically durable and do not easily get scratched, damaged, or marred during use. Finally, in some embodiments, the compositions can be made into decals or films that can be easily applied and removed as needed. Summary of the Invention [Means for solving the problem]

[0007] In view of the foregoing, a composition for imparting anti-fogging properties is disclosed, comprising a hydrogel doped with zwitterions. In one embodiment, a composition for forming a hydrogel that imparts anti-fogging properties to the hydrogel is described, the composition comprising: a charged monomer, at least a portion of which comprises a zwitterionic monomer; and a non-charged hydrophilic monomer, the charged monomer and the non-charged hydrophilic monomer containing reactive groups, the reactive groups reacting together to form a hydrogel having anti-fogging properties.

[0008]

[0008] In another embodiment, an anti-fog material is described comprising a zwitterion-doped hydrogel, the zwitterion-doped hydrogel comprising charged monomer residues, at least a portion of which comprises zwitterionic monomer residues, uncharged hydrophilic monomer residues, and at least one crosslinker residue, the anti-fog material exhibiting a Δ haze value of less than 5% when exposed to fogging conditions.

[0009]

[0009] In yet another embodiment, a coated article is described comprising a substrate and an anti-fog coating, the anti-fog coating comprising a zwitterion-doped hydrogel comprising charged monomer residues, at least a portion of which are zwitterionic monomer residues, uncharged hydrophilic monomer residues, and at least one crosslinker residue.

[0010] In another embodiment, a method for reducing fogging on a surface of a substrate is disclosed, the method comprising applying to the surface of the substrate a zwitterion-doped hydrogel comprising charged monomer residues, at least a portion of which comprises a zwitterionic monomer residue, uncharged hydrophilic monomer residues, and at least one crosslinker residue.Non-limiting examples of articles and surfaces that may benefit from the anti-fog materials described herein include automobile or building windows, camera lenses, medical scope lenses, sensors, eyewear, mirrors, refrigerator doors, or building structures.

[0011]

[0011] As described in more detail below, various embodiments may include at least one additive that aids in the resulting properties of the composition, hydrogel, article or method, such as an additive that aids in adhesion, anti-freeze, crosslinking, film formation, mechanical properties or rheological properties.

[0012]

[0012] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Brief description of the drawings]

[0013] [Figure 1]

[0013] Figures 1A-1C show a coating of the present invention swelling and sheeting water in a hazy environment. Figure 1A shows a substrate 130 having a coating 120 of the present invention in a hazy environment 110 that is saturated with water vapor. Figure 1B shows the coating of the present invention in a swollen state 140 having absorbed water from the environment 110. Figure 1C shows water condensing into a thin transparent sheet 150 on the swollen coating 140 in a hazy environment. [Diagram 2]

[0014] FIG. 2 is a schematic diagram of a laminate of the present invention being applied to a target substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Definition:

[0015] As used herein, "Δ haze" refers to the difference between haze measurements before and after steam exposure, as performed according to ASTM D1003. The haze of samples equilibrated at 25°C was measured using ASTM D1003. The samples were then held over a beaker of boiling water for 30 seconds, and the haze of the samples was evaluated again using ASTM D1003. The first measurement subtracted from the second measurement is defined as "Δ haze". Substrates coated with the materials of the present invention exhibit Δ haze characteristics of less than 5%, such as less than 2% and in many cases less than 1%. In certain embodiments, substrates coated with the materials of the present invention, such as laminates produced according to the present disclosure, exhibit Δ haze in the range of 0.1% to less than 1%, such as 0.1% to 0.8%.

[0015]

[0016] As used herein, "aids adhesion" means to increase the strength of the bond between the coating and the substrate being coated. A standard method for measuring adhesive strength is the ASTM D3359 tape test or crosshatch test.

[0016]

[0017] As used herein, "aiding cross-linking" means increasing the extent or density of cross-links.

[0017]

[0018] As used herein, "aiding film formation" means enhancing the ability of a coating to form a smooth, continuous layer with minimal pinholes or defects.

[0018]

[0019] As used herein, "aiding in frost prevention" means reducing the temperature required to form frost on a material, increasing the time required to form frost on a material, or both.

[0019]

[0020] As used herein, "aiding the mechanical properties" means increasing the scratch resistance, abrasion resistance, hardness, Young's modulus, flexibility, shear modulus, or bend radius of the coating.

[0020]

[0021] As used herein, "aiding the rheological properties" means increasing or decreasing the viscosity of a coating solution to facilitate the process of applying the coating to a substrate.

[0021]

[0022] As used herein, "monomer" refers to a chemical entity having one or more reactive chemical groups configured for polymerization. For example, methacrylate is a monomer having a reactive alkene configured for polymerization.

[0022]

[0023] As used herein, "monomer residue" refers to a chemical fragment that is incorporated into a polymer. For example, polymerization of a methacrylate monomer incorporates a methacrylic residue into a poly(methacrylic) polymer.

[0023]

[0024] A hydrophilic anti-fog coating is disclosed that has excellent fog resistance and durability. The hydrophilic coating provides anti-fog protection by forming a low equilibrium contact angle of less than 30° with a water droplet on the coated surface. This property allows the water droplet to form a flat sheet on the surface, thus preventing optical distortion. An effective anti-fog coating maintains high optical clarity in a foggy environment. This can be quantitatively evaluated by visual observation or by measuring the haze of the film in a foggy environment according to ASTM D1003, or by measuring the degree of distortion of an image viewed through the anti-fog film according to a modification of standard EN-168. The technique includes the steps of preparing a humidity chamber according to the conditions specified in EN-168. On one side of the chamber, a Siemens Star was installed as a visual target, facing the opening of the chamber. The sample was placed over the opening, with the anti-fog coating facing the interior of the humidity chamber. Images were taken every minute and the module transfer functions were calculated using the NIH ImageJ image processing program and compared to the calculated module transfer functions of images taken under non-cloudy conditions.

[0024]

[0025] The mechanisms by which the disclosed coatings may function are illustrated in the figures. For example, Figures 1A-1C show how the coatings of the present invention provide anti-fog properties when placed on a substrate in a humid environment. Figure 1A shows the coating 120 of the present invention on a substrate 130 in a foggy environment 110 filled with water vapor. As shown in Figure 1A, the coating 120 of the present invention, which is below the ambient dew point, is exposed to the environment 110 filled with water vapor, and water molecules from the environment can be absorbed into the coating. As further shown in Figure 1B, the absorption of water vapor causes the coating 140 to swell, slowing the formation of liquid water droplets due to condensation on the surface that can distort transparency through the coating. Figure 1C further shows that after the coating 140 of the present invention begins to swell, additional water vapor can condense and spread on the swollen coating 140, forming a flat transparent sheet 150 on the swollen coating 140.

[0025]

[0026] FIG. 2 illustrates an embodiment of the present invention 200 showing a coating 210 applied to a target substrate 240. In this embodiment, the active coating 210 is applied to the target substrate 240 using a suitable optional transparent substrate 220, and optionally backed with a transparent adhesive 230. The optional transparent substrate and transparent adhesive allow coatings produced according to the present disclosure to be easily applied to a wide variety of surfaces that would benefit from such coatings. The checkboxes 250 surrounding layers 210, 220, and 230 reflect the composite that constitutes a laminate according to one embodiment of the present disclosure, without including the substrate. Non-limiting examples of such surfaces that may form the substrate include automobile windows, camera lenses, sensors such as lidar, radar, microwave, optical sensors, eyewear such as glasses, visors, masks, goggles, shields, and sunglasses, freezer windows, and mirrors such as bathroom mirrors.

[0026]

[0027] In embodiments of the invention where the coating is applied as a laminate decal, processing and application issues can be handled during manufacture. As a result, the coating can be highly crosslinked, textured, applied at an optimal thickness, or engineered into a multi-layer structure when applied to the film. When the user receives the product, they simply need to adhere it to the desired substrate. As a result, the performance and durability of the coating can be fully optimized ex situ while simultaneously enhancing ease of application.

[0027]

[0028] Additionally, in embodiments of the present invention where the coating is applied as a laminate decal, if the coating becomes damaged during operation of the target substrate, it may be easily removed and replaced by peeling the decal off the target substrate, allowing for easy maintenance since no solvents are required to remove the coating from the substrate and no highly specialized equipment is required to reapply.

[0028]

[0029] The anti-fog coating includes a charged monomer, an uncharged monomer, and a crosslinker. The charged monomer includes a hydrophilic portion that results in the excellent anti-fog properties of the coating. At least some of the charged monomers are zwitterionic monomers, such as phosphorylcholine, carboxybetaine, sulfobetaine such as N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (also known as DMAPS), 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, or carboxybetaine methacrylate. Zwitterionic molecules have both positive and negative portions, so the charge is balanced even in the absence of a counterion. These zwitterionic materials tend to be very hydrophilic and retain good hydrophilicity over a wide range of pH and salt concentrations.

[0029]

[0030] In one embodiment, the charged monomers can also include monomers that carry acidic functionality, basic functionality, or neutralized acidic or basic entities, such as monovalently charged monomers that contain carboxylic acids, such as acrylic acid or methacrylic acid, sulfonic acids, such as 2-acrylamido-2-methylpropanesulfonic acid (AMPS), quaternary amines, or other similar moieties.

[0030]

[0031] The remainder of the polymer may be formed from one or more monomers, such as vinylpyrrolidone, acrylamide, acrylates or methacrylates including polyethylene glycol, hydroxyethyl methacrylate, maleic anhydride, vinyl alcohol, vinyl acetate, vinylpyridine, diethylaminoethyl methacrylate (DEAMA), cellulosic polymers, or other similar monomers, or monomers containing any of the functional groups thereof.

[0031]

[0032] Importantly, zwitterionic materials suffer from the "anti-polyelectrolyte effect"; that is, they are poorly soluble and undergo low swelling in deionized water, but are capable of higher water uptake in the presence of salt. Conventional hydrogels based on singly charged monomers exhibit the opposite behavior, collapsing or even becoming hydrophobic in the presence of salt. By blending singly charged and zwitterionic monomers, a final polymer hydrogel can be obtained with more consistent swelling behavior over a range of salt concentrations and pH. The present disclosure utilizes this effect as a basis for developing durable anti-fog coatings. This strategy allows the use of lower amounts of expensive and mechanically weak zwitterionic materials while still achieving good fogging performance. These charged monomers react with non-charged hydrophilic monomers, such as hydroxyethyl methacrylate, in multiple formulations, imparting mechanical strength to the film without imparting hydrophobicity. Some of the monomers may be pre-polymerized to form oligomers or short polymers to aid in processing the coating.

[0032]

[0033] Additionally, a crosslinking agent is added to increase the degree of crosslinking, enhancing the mechanical properties of the film and making it less easily washed off in water. The crosslinking agent can contain multiple vinyl groups capable of undergoing free radical polymerization, such as multifunctional polyethylene glycol acrylates or hydrophilic urethane acrylates. Films prepared in this manner can incorporate photoinitiators that enable the crosslinking reaction. The photoinitiator is activated by ultraviolet light to harden or crosslink the film.

[0033]

[0034] Alternatively, the crosslinker can consist of thermally or pH-activated crosslinking groups, such as blocked or unblocked isocyanates, aziridines, melamines, epoxides, oxazolines, amines, hydrazides, glutaraldehyde, silanes, epoxies, or carbodiimides. These groups can react with non-zwitterionic monomers and crosslink the film when exposed to a sufficiently high temperature or a specific pH. Dynamic binding species such as borate ions, Zn 2+ or Fe 3+ Metal ions such as can be incorporated as well. Different crosslinking systems can be selected or combined to optimize the balance of anti-fog properties, mechanical properties, and ease of processing in preparing the film.

[0034]

[0035] The active layer may also include additives that aid in crosslinking, film formation, rheological properties, or other properties of the active layer. The active layer may also include additives such as nanoparticles, waxes, or other polymeric resins that affect the mechanical properties, rheological properties, film forming ability, or other properties of the active layer. The active layer may also include some surfactants or other types of additives to improve the film forming ability of the active material.

[0035]

[0036] The active layer can be formed from a precursor solution. The solution of the active layer precursor is applied to a substrate, which can be polyester, polycarbonate, polyacrylate, glass, cellulose acetate, cellulose triacetal, or other material. The substrate can be pretreated with chemical reagents, plasma, corona discharge, UV radiation, ozone, or other treatments to activate the surface and enhance adhesion between the active layer and the substrate.

[0036]

[0037] The molecular weight of the polymer applied to the substrate can range from 0.5 kDa to 100 MDa, or can be applied as a monomer, oligomer, or prepolymer and then polymerized.

[0037]

[0038] In one embodiment, one or more solvents can be used, non-limiting examples of which include water, alcohols such as methanol, ethanol, and isopropanol, amines such as ammonium hydroxide or triethylamine, ketones such as ethers, acetone, ethyl acetate, or methyl ethyl ketone, or others appropriate for the polymer in question.

[0038]

[0039] In one embodiment, one or more fillers can be used. Non-limiting examples of such fillers include silica particles, alumina particles, calcium carbonate particles, cellulose nanocrystals, particles of insoluble polymers, clays, etc. These particles can improve the mechanical properties of the coating or improve the heat transport properties to reach the temperature of the surrounding environment more quickly.

[0039]

[0040] In one embodiment, one or more additives can be used. Non-limiting examples of such additives include leveling additives, antifoam additives, surfactants, and surface tension control additives, which improve the coating's ability to resist dirt, form a film, and resist damage. Some additives, such as propylene glycol, ethylene glycol, other glycols, non-volatile alcohols, esters, and ketones, can be added to swell the polymer.

[0040]

[0041] In one embodiment, the additives can include inorganic salts, which can help the coating to resist the formation of ice or frost. Some additives include amine-containing molecules, such as polyethyleneimine, or thiol-containing molecules that improve crosslinking and adhesion to the substrate.

[0041]

[0042] In embodiments where the coating is applied as a laminate decal, the transparent substrate may be many different transparent media, including polyesters such as polycarbonate, PMMA, PET, polyurethane, vinyl polymers, cellulose acetate, triacetal cellulose, rubber, or any other suitable polymer. The transparent substrate may be used as received, or may be treated in a number of different ways to modify the adhesion of the active layer to the substrate, including micropatterning the surface using imprint lithography, roughening the surface to add texture, oxidizing the surface by exposing the surface to UV radiation, oxidizing the surface by exposing the surface to UV-ozone, treating the surface with plasma, treating the surface with corona discharge, treating the surface with a chemical primer such as a diamine, or applying a photoinitiator directly to the surface. Alternatively, the active layer may be cast onto a release material (such as PTFE) and the adhesive applied directly to the active layer. The laminate decal may be adhered to the target substrate by adhesive, electrostatic adhesion, friction, or other adhesion mechanisms.

[0042]

[0043] In a first embodiment, a composition for forming a hydrogel that imparts anti-fogging properties to the hydrogel is described, the composition comprising: a charged monomer, at least in part comprising a zwitterionic monomer; and a non-charged hydrophilic monomer, the charged monomer and the non-charged hydrophilic monomer containing reactive groups, which react with each other to form the hydrogel having anti-fogging properties.

[0043]

[0044] In a first embodiment, the zwitterionic monomer can include phosphorylcholine, carboxybetaine, and sulfobetaine. For example, the zwitterionic monomer can include N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, or carboxybetaine methacrylate.

[0044]

[0045] In a first embodiment, the concentration of zwitterionic monomer in the material is greater than 0% and less than 75% by weight, such as greater than 0% and less than 50% by weight, or even greater than 0% and less than 25% by weight.

[0045]

[0046] In a first embodiment, the charged monomer further comprises an acrylate or methacrylate containing a carboxylic acid, sulfonic acid, or quaternary amine functional group.

[0046]

[0047] The charged monomers are hydrophilic at pH 2 to 9 or 0 M to 1 M sodium chloride solutions. Thus, the charged monomers have acidic functionality, basic functionality, or are neutralized acid or base salts.

[0047]

[0048] In a first embodiment, the non-charged hydrophilic monomer can include vinyl pyrrolidone, acrylamide, ethylene glycol-containing acrylates or methacrylates, hydroxyethyl methacrylate, vinyl alcohol, vinyl acetate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or other acrylates or methacrylates that are hydrophilic but retain a non-charged portion.

[0048]

[0049] In a first embodiment, the composition may further comprise at least one crosslinking agent. In one embodiment, the at least one crosslinking agent is found in the composition in an amount sufficient to form a crosslinked polymer, for example in an amount ranging from 2% to 35% by weight, for example from 4% to 25% by weight, or even from 5% to 20% by weight, which imparts anti-fog properties to the crosslinked polymer.

[0049]

[0050] In a first embodiment, the at least one crosslinker can include a molecule having a vinyl group capable of undergoing free radical polymerization. For example, the at least one crosslinker that includes a molecule having a vinyl group capable of undergoing free radical polymerization includes a multifunctional polyethylene glycol acrylate or a hydrophilic urethane acrylate. The at least one crosslinker can include a molecule that contains a moiety that can react with a carboxy group, an alcohol group, or an amine functional group. For example, the moiety can be selected to be capable of reacting with a carboxy group, an alcohol group, an epoxy group, a carbonyl group, or an amine functional group, and can include carbodiimide, isocyanate, azideline, oxazoline, amine, hydrazide, silane, epoxy, melamine, and other amino crosslinkers.

[0050]

[0051] In a first embodiment, the composition may further include at least one photoinitiator including a phosphine oxide, a phenone, an azo initiator, a peroxide, or a benzoyl. The phosphine oxide may include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the phenone may include 2-hydroxy-2-methylpropiophenone or benzophenone, azobisisobutyronitrile, the peroxide may include benzoyl peroxide, and the benzoyl may include 2,2-dimethoxy-1,2-diphenyl-ethan-1-one.

[0051]

[0052] In a first embodiment, the composition may further comprise at least one additive that aids in the adhesion, crosslinking, film formation, antifreeze, mechanical properties or rheological properties of the antifog material. For example, the at least one additive that aids in adhesion may comprise (3-aminopropyl)triethoxysilane or polyethyleneimine. The at least one additive that aids in antifreeze properties may comprise glycerol, ethylene glycol, propylene glycol, or polyethylene glycol. The at least one additive that aids in mechanical properties may comprise at least one nanoparticle or polymer resin. For example, the at least one nanoparticle may comprise silica nanoparticles, alumina nanoparticles, cellulose nanoparticles, or other inorganic fillers.

[0052]

[0053] The at least one polymeric resin may include polyurethane, polyacrylate, polymethacrylate, polystyrene, polyethylene, polypropylene, paraffin wax, natural wax, or combinations thereof.

[0053]

[0054] The at least one additive that aids in film formation can include Triton, Tween, sodium dodecyl sulfate, or cetyltrimethylammonium bromide surfactants, dispersants, styrene maleic acid copolymers, leveling agents, or silicone and / or polyether modified polyacrylates.

[0054]

[0055] In a first embodiment, the composition may further comprise a carrier solvent including water, volatile alcohols, volatile ketones, volatile ethers, and volatile amines.

[0055]

[0056] In a second embodiment, an anti-fog material is described that includes a zwitterion-doped hydrogel that includes charged monomer residues, at least in part including zwitterionic monomer residues, uncharged hydrophilic monomer residues, and at least one crosslinker residue, and the anti-fog material exhibits a delta haze value of less than 5% when exposed to fogging conditions.

[0056]

[0057] In a second embodiment, the zwitterionic monomer residue can include phosphorylcholine, carboxybetaine, and sulfobetaine. For example, the zwitterionic monomer residue can include residues of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, or carboxybetaine methacrylate.

[0057]

[0058] In a second embodiment, the concentration of zwitterionic monomer residues in the material can be greater than 0% and less than 75% by weight, such as greater than 0% and less than 50% by weight, or even greater than 0% and less than 25% by weight.

[0058]

[0059] In a second embodiment, the charged monomer residues can further include acrylates or methacrylates containing carboxylic acid, sulfonic acid, or quaternary amine functional groups.

[0059]

[0060] In a second embodiment, the charged monomer residues may be hydrophilic in sodium chloride solutions at pH 2 to 9 or 0 M to 1 M. Thus, the charged monomers have acidic functionality, basic functionality, or are neutralized acid or base salts.

[0060]

[0061] In a second embodiment, the non-charged hydrophilic monomer residue can include residues of vinylpyrrolidone, acrylamide, ethylene glycol-containing acrylates or methacrylates, hydroxyethyl methacrylate, vinyl alcohol, vinyl acetate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or other acrylates or methacrylates that are hydrophilic but retain a non-charged portion.

[0061]

[0062] In a second embodiment, the at least one crosslinker residue can include a residue of a molecule having a vinyl group capable of undergoing free radical polymerization. For example, the at least one crosslinker residue can include a residue of a molecule having a vinyl group capable of undergoing free radical polymerization, and can include a multifunctional polyethylene glycol acrylate, or a hydrophilic urethane acrylate.

[0062]

[0063] In a second embodiment, at least one crosslinker residue can include a residue of a molecule that contains a moiety capable of reacting with a carboxy, alcohol, epoxy, carbonyl, or amine functional group. For example, the moiety can be selected to be capable of reacting with a carboxy, alcohol, or amine functional group, and can include carbodiimides, isocyanates, azides, oxazolines, amines, hydrazides, silanes, epoxies, melamines, and other amino crosslinkers.

[0063]

[0064] The second embodiment may further include at least one photoinitiator including phosphine oxide, phenone, azobisisobutyronitrile, peroxide, or benzoyl. For example, the phosphine oxide may include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the phenone may include 2-hydroxy-2-methylpropiophenone or benzophenone, azobisisobutyronitrile, the peroxide may include benzoyl peroxide, and the benzoyl may include 2,2-dimethoxy-1,2-diphenyl-ethan-1-one.

[0064]

[0065] The second embodiment can further include at least one additive that aids in the adhesion, crosslinking, film formation, antifreeze, mechanical properties, or rheological properties of the antifog material. For example, the at least one additive that aids in adhesion can include (3-aminopropyl)triethoxysilane or polyethyleneimine. The at least one additive that aids in antifreeze properties can include glycerol, ethylene glycol, propylene glycol, or polyethylene glycol.

[0065] The at least one additive that aids in mechanical properties can include at least one of nanoparticles or polymeric resins.

[0066]

[0066] The at least one nanoparticle may include silica nanoparticles, alumina nanoparticles, cellulose nanoparticles, or other inorganic fillers. The at least one polymeric resin may include polyurethane, polyacrylate, polymethacrylate, polystyrene, polyethylene, polypropylene, paraffin wax, natural wax, or combinations thereof. The at least one additive that aids in film formation may include Triton, Tween, sodium dodecyl sulfate, or cetyltrimethylammonium bromide surfactants, dispersants, styrene maleic acid copolymers, leveling agents, or silicone and / or polyether modified polyacrylates.

[0067]

[0067] A third embodiment is directed to a coated article comprising a substrate and an anti-fog coating, the anti-fog coating comprising a zwitterion-doped hydrogel comprising charged monomer residues, at least a portion of which comprises zwitterionic monomer residues, uncharged hydrophilic monomer residues, and at least one crosslinker residue.

[0068] In a third embodiment, the zwitterionic monomer residue can include a residue of phosphorylcholine, carboxybetaine, or sulfobetaine. For example, the zwitterionic monomer residue can include a residue of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, or carboxybetaine methacrylate.

[0069]

[0069] In a third embodiment, the concentration of zwitterionic monomer residues in the material can be greater than 0% and less than 75% by weight, for example, greater than 0% and less than 50% by weight, or even greater than 0% and less than 25% by weight.

[0070] In a third embodiment, the charged monomer residues can further include residues of acrylates or methacrylates containing carboxylic acid, sulfonic acid, or quaternary amine functional groups.

[0071] In a third embodiment, the charged monomer residues may be hydrophilic in sodium chloride solutions at pH 2 to 9 and salt concentrations of 0 M to 1 M. As a result, the charged monomers may have acidic functionality, basic functionality, or are neutralized acid or base salts.

[0072]

[0072] In a third embodiment, the non-charged hydrophilic monomer residues may include residues of vinylpyrrolidone, acrylamide, ethylene glycol-containing acrylates or methacrylates, hydroxyethyl methacrylate, vinyl alcohol, vinyl acetate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or other acrylates or methacrylates that are hydrophilic but retain a non-charged portion.

[0073] In a third embodiment, the at least one crosslinker residue can include a molecule having a vinyl group capable of undergoing free radical polymerization. For example, the at least one crosslinker residue can include a residue of a molecule having a vinyl group capable of undergoing free radical polymerization and can include a multifunctional polyethylene glycol acrylate, or a hydrophilic urethane acrylate. The at least one crosslinker residue can include a residue of a molecule containing a moiety capable of reacting with a carboxy, alcohol, epoxy, carbonyl, or amine functional group. For example, the moiety can be selected to be capable of reacting with a carboxy, alcohol, or amine functional group and can include carbodiimides, isocyanates, azidelines, oxazolines, amines, hydrazides, silanes, epoxies, melamines, and other amino crosslinkers.

[0074] The third embodiment may further include at least one photoinitiator including a phosphine oxide, a phenone, an azobisisobutyronitrile, a peroxide, or a benzoyl.

[0075]

[0075] In a third embodiment, the phosphine oxide may include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the phenone may include 2-hydroxy-2-methylpropiophenone or benzophenone, azobisisobutyronitrile, the peroxide may include benzoyl peroxide, and the benzoyl may include 2,2-dimethoxy-1,2-diphenyl-ethan-1-one.

[0076]

[0076] The third embodiment may further include at least one additive that aids in the adhesion, crosslinking, film formation, anti-freeze, mechanical or rheological properties of the anti-fog material. The at least one additive that aids in adhesion may include (3-aminopropyl)triethoxysilane or polyethyleneimine. The at least one additive that aids in anti-freeze properties may include glycerol, ethylene glycol, propylene glycol, or polyethylene glycol. The at least one additive that aids in mechanical properties may include at least one nanoparticle or polymer resin.

[0077]

[0077] The at least one nanoparticle can include silica nanoparticles, alumina nanoparticles, cellulose nanoparticles, or other inorganic fillers. For example, the at least one polymeric resin can include polyurethane, polyacrylate, polymethacrylate, polystyrene, polyethylene, polypropylene, paraffin wax, natural wax, or combinations thereof. The at least one additive that aids in film formation can include Triton, Tween, sodium dodecyl sulfate, or cetyltrimethylammonium bromide surfactants, dispersants, styrene maleic acid copolymers, leveling agents, or silicone and / or polyether modified polyacrylates.

[0078]

[0078] The third embodiment may be in the form of a laminate, and the laminate may include a transparent substrate, a transparent adhesive, and a coating. For example, the adhesive may include an adhesive selected from an acrylic adhesive, a silicone adhesive, a urethane heat seal adhesive, a polyethylene heat seal adhesive, and combinations thereof. The transparent substrate may include polyethylene, polyethylene terephthalate, polycarbonate, cellulose acetate, triacetal cellulose, polyacrylate, or combinations thereof.

[0079]

[0079] The coated articles described herein and exemplified in the third embodiment may exhibit a delta haze value of less than 5% when exposed to foggy conditions. Non-limiting examples of articles encompassed by the third embodiment include an automobile or building window, a camera lens, a medical scope lens, a sensor, eyewear, a mirror, a refrigerator door, or a building structure.

[0080]

[0080] In a fourth embodiment, a method for producing a surface of a substrate that is resistant to fogging is disclosed, the method comprising the step of applying to the surface of the substrate a zwitterion-doped hydrogel comprising charged monomer residues, at least a portion of which include zwitterionic monomer residues, uncharged hydrophilic monomer residues, and at least one crosslinker residue.

[0081] In a fourth embodiment, the zwitterionic monomer residue can include phosphorylcholine, carboxybetaine, or sulfobetaine. For example, the zwitterionic monomer residue can include a residue of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, or carboxybetaine methacrylate.

[0082]

[0082] In a fourth embodiment, the concentration of zwitterionic monomer residues in the material may be greater than 0% and less than 75% by weight, for example, greater than 0% and less than 50% by weight, or even greater than 0% and less than 25% by weight.

[0083] In a fourth embodiment, the charged monomer residues can further include residues of acrylates or methacrylates containing carboxylic acid, sulfonic acid, or quaternary amine functional groups.

[0084] In a fourth embodiment, the charged monomer residues may be hydrophilic at a pH of 2 to 9 or 0 M to 1 M sodium chloride solution. As a result, the charged monomer residues may have acidic functionality, basic functionality, or are neutralized acid or base salts.

[0085]

[0085] In a fourth embodiment, the non-charged hydrophilic monomer residues may include residues of vinylpyrrolidone, acrylamide, ethylene glycol-containing acrylates or methacrylates, hydroxyethyl methacrylate, vinyl alcohol, vinyl acetate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or other acrylates or methacrylates that are hydrophilic but retain a non-charged portion.

[0086] In a fourth embodiment, the at least one crosslinker residue can include a residue of a molecule having a vinyl group capable of undergoing free radical polymerization. For example, the at least one crosslinker residue can include a residue of a molecule having a vinyl group capable of undergoing free radical polymerization and can include a multifunctional polyethylene glycol acrylate, or a hydrophilic urethane acrylate. The at least one crosslinker residue can include a residue of a molecule containing a moiety capable of reacting with a carboxy, alcohol, epoxy, carbonyl, or amine functional group. The moiety is selected to be capable of reacting with a carboxy, alcohol, or amine functional group and can include carbodiimides, isocyanates, azidelines, oxazolines, amines, hydrazides, silanes, epoxies, melamines, and other amino crosslinkers.

[0087]

[0087] The fourth embodiment may further include at least one photoinitiator including a phosphine oxide, a phenone, an azobisisobutyronitrile, a peroxide, or a benzoyl. The phosphine oxide may include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the phenone may include 2-hydroxy-2-methylpropiophenone or benzophenone, an azobisisobutyronitrile, the peroxide may include benzoyl peroxide, and the benzoyl may include 2,2-dimethoxy-1,2-diphenyl-ethan-1-one.

[0088]

[0088] The fourth embodiment may further include at least one additive that aids in the adhesion, crosslinking, film formation, anti-freeze, mechanical properties, or rheological properties of the anti-fog material. For example, the at least one additive that aids in adhesion may include (3-aminopropyl)triethoxysilane or polyethyleneimine. The at least one additive that aids in anti-freeze properties may include glycerol, ethylene glycol, propylene glycol, or polyethylene glycol. The at least one additive that aids in mechanical properties may include at least one nanoparticle or polymer resin.

[0089] In a fourth embodiment, the at least one nanoparticle may comprise silica nanoparticles, alumina nanoparticles, cellulose nanoparticles, or other inorganic fillers. The at least one polymer resin may comprise polyurethane, polyacrylate, polymethacrylate, polystyrene, polyethylene, polypropylene, paraffin wax, natural wax, or a combination thereof.

[0090]

[0090] In a fourth embodiment, the at least one additive that assists in film formation may include Triton, Tween, sodium dodecyl sulfate, or cetyltrimethylammonium bromide surfactants, dispersants, styrene maleic acid copolymers, leveling agents, or silicone and / or polyether modified polyacrylates.

[0091] In a fourth embodiment, the substrate can be a laminate including a transparent substrate, a transparent adhesive, and a coating. The transparent substrate can be modified by plasma, UV, ozone, or other chemical surface modification techniques. The laminate can be in the form of a film or a decal.

[0092] The fourth embodiment may further include coating the zwitterionic hydrogel by at least one technique selected from roll-to-roll, blade coating, dipping, needle dispensing, or spraying. The method may include stepwise, sequential application of a subset of the components in the form of a laminate. The method may include applying a primer or adhesion promoter before applying the other components. It may also include reapplication of one or more components to enhance coating performance over time when a second application of the coating formulation is applied over the first. It is understood that some components of the formulation may be applied over the first application.

[0093] In one embodiment, the anti-freeze material can be applied over an existing coating by spraying, wiping, blade coating, or dipping.

[0094]

[0094] The substrates described herein can include glass, plastic, porcelain, metal, or combinations thereof. Similarly, the substrates can include automobile or building windows, camera lenses, medical scope lenses, sensors, eyewear, mirrors, refrigerator doors, or building structures.

[0095] In a fourth embodiment, the substrate can be treated prior to application of the coating material, such as by plasma, UV or ozone treatment, or other chemical surface modification techniques. The methods described herein can include in situ crosslinking of the zwitterionic hydrogel on the substrate after application. For example, crosslinking can be performed at ambient room temperature conditions or at elevated temperature and humidity conditions.

[0096]

[0096] The features and advantages of the present invention are more fully illustrated by the following examples, which are provided for illustrative purposes and are not to be construed as limiting the invention in any way. EXAMPLES

[0097] The following examples disclose methods of preparing anti-fog compositions and films containing zwitterion-doped hydrogels.

[0098] Example 1 This example provides a method of preparing a film comprising a prepolymer antifog composition and a zwitterion-doped hydrogel having improved performance characteristics in accordance with the present disclosure.

[0099]

[0099] A randomly polymerized prepolymer containing 8.8% by weight of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2.8% by weight of 2-acrylamido-2-methylpropanesulfonic acid, and 88.4% by weight of hydroxyethyl methacrylate was dissolved in the mixture to obtain a composition of 12.5% ​​by weight of prepolymer, 37.5% by weight of water, 36% by weight of ethanol, 7% by weight of polyethylene glycol diacrylate, 5% by weight of ethyl acetate, 1% by weight of photopolymerization initiator, and 1% by weight of leveling additive and surfactant.

[0100] A transparent substrate comprising an adhesive-backed polyethylene terephthalate sheet was treated with a corona discharge and a uniform film of the coating solution was applied with a blade coater. The solution was irradiated with UV light (approximately 365 nm) for 30 minutes and heated in an oven at 80° C. for 15 minutes. The laminate decal was then applied to a glass substrate using an adhesive.

[0101]

[0101] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment created by holding it over boiling water for at least 30 seconds. The sample remained clear for longer than 30 seconds. After holding it over boiling water for 30 seconds, the delta haze (difference in haze measurements before and after steam exposure, performed according to ASTM D1003) of the untreated glass slide is greater than 30%. The delta haze of the coated glass slide exposed to the same conditions was 0.8%.

[0102] Example 2

[0102] In this example, a randomly polymerized prepolymer containing 25.5% by weight of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 4.8% by weight of acrylic acid, and 69.7% by weight of hydroxyethyl methacrylate was dissolved in the mixture to obtain a composition of 8.7% by weight of prepolymer, 71.2% by weight of water, 20% by weight of ethanol, 0.025% by weight of antifoam additive, 0.25% by weight of leveling additive, 0.3% by weight of wax additive, and 0.25% by weight of surfactant.

[0103]

[0103] Before coating application, 1 part Carbodilite SV-02 was added to 20 parts of the coating solution. During coating, an adhesive-backed PET film was treated with a corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 125°C for 5 minutes. The laminate decal was then applied to a glass substrate using the adhesive.

[0104]

[0104] The anti-fog properties of this example were tested by exposing the coated substrate, formed in a manner similar to that of Example 1, to a high humidity environment, e.g., the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated glass was 0.1%.

[0105] Example 3

[0105] In this example, a randomly polymerized prepolymer containing 32.0 wt. % N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 7.2 wt. % acrylic acid, 58.4 wt. % hydroxyethyl methacrylate, and 2.4 wt. % methyl methacrylate was dissolved in the mixture to obtain a composition of 13 wt. % prepolymer, 64.8 wt. % water, 22 wt. % ethanol, and 0.2 wt. % leveling additive.

[0106]

[0106] Before coating application, 1 part of carbodiimide crosslinker (such as Carbodilite SV-02) is added to 20 parts of the coating solution. During coating, an adhesive-backed PET film was treated with corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 130°C for 5 minutes. The laminate decal was then applied to a glass substrate using the adhesive.

[0107] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment. As in the previous example, the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.1%.

[0108]

[0108] The mechanical properties of this example were tested by immersing the sample in deionized water for 5 minutes and then wiping the coating dry with a lint-free paper towel. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.5%.

[0109] Example 4

[0109] In this example, a randomly polymerized prepolymer containing 32.0 wt% N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 7.2 wt% acrylic acid, 58.4 wt% hydroxyethyl methacrylate, and 2.4 wt% methyl methacrylate was dissolved in the mixture to obtain a composition of 13 wt% prepolymer, 64.8 wt% water, 22 wt% ethanol, and 0.2 wt% leveling additive.

[0110]

[0110] Before coating application, 1 part Carbodilite V-02-L2 was added to 20 parts of the coating solution. During coating, a sheet of transparent polycarbonate was treated with a corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 130°C for 5 minutes.

[0111] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment. As in the previous example, the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated polycarbonate was 0.4%.

[0112] Example 5

[0112] In this example, a randomly polymerized prepolymer containing 33.0 wt% N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 5.0 wt% acrylic acid, 59.0 wt% hydroxyethyl methacrylate, and 3.0 wt% methyl methacrylate was dissolved in a mixture to obtain a composition of 12.1 wt% prepolymer, 57 wt% water, 23 wt% isopropanol, 0.20 wt% leveling additive, 0.8 wt% triethylamine, and 6.9 wt% Cymel 385.

[0113] During coating, an adhesive-backed PET film was treated with a corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 130° C. for 5 minutes. The laminate decal was then applied to a glass substrate using the adhesive.

[0114] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment. As in the previous example, the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.3%.

[0115]

[0115] The mechanical properties of this example were tested by immersing the sample in deionized water for 5 minutes and then wiping the coating dry with a lint-free paper towel. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 1.5%.

[0116] Example 6

[0116] In this example, 10% by weight of a prepolymer containing 32.0% by weight of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 7.2% by weight of acrylic acid, 58.4% by weight of hydroxyethyl methacrylate, and 2.4% by weight of methyl methacrylate was dissolved in the mixture to obtain a composition of 10% by weight of prepolymer, 65.2% by weight of water, 22% by weight of ethanol, 1.7% by weight of colloidal silica, 0.9% by weight of dispersant, and 0.2% by weight of leveling additive.

[0117] The cleaned substrate was treated with an adhesive such as a solution of 2% aminopropyltriethoxysilane in ethanol. After the solvent evaporated, the substrate was baked at 100°C for 2 minutes and then wiped clean with rubbing alcohol. 1 part Carbodilite SV-02 was added to 20 parts of the coating solution prior to coating application. The coating solution was applied to the treated glass substrate via a blade coater, dried, and cured by heating at 130°C for 5 minutes.

[0118] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment. As in the previous example, the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated glass was 0.1%.

[0119] Example 7

[0119] In this example, a randomly polymerized prepolymer containing 32.0 wt. % N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 7.2 wt. % acrylic acid, 58.4 wt. % hydroxyethyl methacrylate, and 2.4 wt. % methyl methacrylate was dissolved in the mixture to obtain a composition of 13 wt. % prepolymer, 59.4 wt. % water, 27.5 wt. % isopropanol, and 0.1 wt. % leveling additive.

[0120]

[0120] Before applying the coating, a solution containing 10% by weight of tetraethoxysilane, 10% by weight of (3-glycidoxypropyl)methyldiethoxysilane, and 80% by weight of isopropanol is prepared. 3 parts of the solution of silane in isopropanol and 2 parts of Carbodilite SV-02 are added to 32 parts of the coating solution. During coating, an adhesive-backed PET film is treated with a corona discharge and coated on its surface with a coating blade. The coating is dried and cured by heating at 130°C for 5 minutes. The laminate decal is then applied to a glass substrate using the adhesive.

[0121] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment. As in the previous example, the coated substrate was held over boiling water and remained transparent for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.2%.

[0122]

[0122] The mechanical properties of this example were tested by immersing the sample in deionized water for 5 minutes and then wiping the coating dry with a lint-free paper towel. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.8%.

[0123] Comparative Example 1

[0123] This comparative example does not include a zwitterionic monomer. A prepolymer containing 9 wt% acrylic acid, 88 wt% hydroxyethyl methacrylate, and 3 wt% methyl methacrylate was dissolved in the mixture to give a composition of 13% prepolymer, 64.8% water, 22% ethanol, and 0.2% leveling additive.

[0124]

[0124] Before coating application, 1 part of carbodiimide crosslinker Carbodilite SV-02 was added to 20 parts of the coating solution. During coating, an adhesive-backed PET film was treated with corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 130°C for 5 minutes. The laminate decal was then applied to a glass substrate using the adhesive.

[0125] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment as described above. As in the previous example, the coated substrate was held over boiling water and remained clear for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 19.6%.

[0126] Comparative Example 2

[0126] This comparative example does not contain a crosslinking agent. In this example, a randomly polymerized prepolymer containing 32.0% by weight of N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 7.2% by weight of acrylic acid, 58.4% by weight of hydroxyethyl methacrylate, and 2.4% by weight of methyl methacrylate was dissolved in the mixture to obtain a composition of 13% by weight of prepolymer, 59.4% by weight of water, 27.5% by weight of isopropanol, and 0.1% by weight of leveling additive.

[0127] During coating, an adhesive-backed PET film was treated with a corona discharge and coated on its surface with a coating blade. The coating was dried and cured by heating at 130° C. for 5 minutes. The laminate decal was then applied to a glass substrate using the adhesive.

[0128] The anti-fog properties of this example were tested by exposing the coated substrate to a high humidity environment as described above. As in the previous example, the coated substrate was held over boiling water and remained clear for more than 30 seconds. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 0.5%.

[0129]

[0129] The mechanical properties of this example were tested by immersing the sample in deionized water for 5 minutes, then wiping the coating off with a lint-free paper towel and drying. Visually, the coating appeared to have been wiped off with the towel. After being held over boiling water for 30 seconds, the delta haze of the coated laminate adhered to a glass slide was 67.8%. [Industrial Applicability]

[0130] The disclosed anti-fog coatings including zwitterion doped hydrogels and methods for making decals or films may be applicable to a variety of industrial or consumer applications where optical clarity is required and fogging is detrimental to the application. Non-limiting examples of such uses include automotive windows, camera lenses, sensors such as lidar, radar, microwave, optical sensors, eyewear such as glasses, visors, masks, goggles, shields, and sunglasses, freezer windows, and coatings on mirrors such as bathroom mirrors.

[0131]

[0131] Additionally, architectural designs that may benefit from the use of the various embodiments disclosed herein include various glass and plastic products in different portions of a building, such as storefront displays and windows, greenhouses, cold storage food displays and freezer windows, shower doors, and glass enclosures around sporting events such as ice hockey rinks.

[0132]

[0132] The embodiments disclosed herein can be used to coat cameras attached to scopes used in a variety of medical applications. For example, endoscopes including gastroscopes, bronchoscopes, cystoscopes, ureteroscopes, arthroscopes, and colonoscopes can all benefit from the anti-fog properties associated with the disclosed invention.

[0133]

[0133] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope of the invention being indicated by the following claims.

Claims

1. 1. A composition for forming a hydrogel that imparts anti-fogging properties to said hydrogel, comprising: The composition comprises: charged monomers, at least a portion of which comprises zwitterionic monomers; and Uncharged hydrophilic monomers wherein the charged monomers and the uncharged hydrophilic monomers contain reactive groups, and the reactive groups react with each other to form the hydrogel having anti-fogging properties; The composition, wherein the hydrogel exhibits a delta haze value of less than 5% when exposed to hazy conditions.

2. 10. The composition of claim 1, wherein the zwitterionic monomer comprises phosphorylcholine, carboxybetaine, sulfobetaine, or a combination thereof.

3. 3. The composition of claim 2, wherein the zwitterionic monomer comprises N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine, 2-methacryloyloxyethyl phosphorylcholine, sulfobetaine acrylamide, carboxybetaine methacrylate, or a combination thereof.

4. 10. The composition of claim 1, wherein the concentration of zwitterionic monomer in the material is greater than 0% and less than 75% by weight.

5. 10. The composition of claim 1, wherein the concentration of zwitterionic monomer in the material is greater than 0% and less than 50% by weight.

6. 10. The composition of claim 1, wherein the concentration of zwitterionic monomer in the material is greater than 0% and less than 25% by weight.

7. The composition of claim 1 , wherein the charged monomer further comprises an acrylate or methacrylate containing a carboxylic acid, sulfonic acid, or quaternary amine functionality.

8. The composition of claim 1 , wherein the charged monomer is hydrophilic in a sodium chloride solution at a pH of 2 to 9 or 0 M to 1 M.

9. The composition of claim 1 , wherein the charged monomer has acid functionality, basic functionality, or is a neutralized acid or base salt.

10. 10. The composition of claim 1, wherein the uncharged hydrophilic monomer comprises vinyl pyrrolidone, acrylamide, ethylene glycol-containing acrylate or methacrylate, hydroxyethyl methacrylate, vinyl alcohol, vinyl acetate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, or other acrylates or methacrylates that are hydrophilic but retain an uncharged moiety.

11. The composition of claim 1 further comprising at least one crosslinking agent.

12. The composition of claim 11 , wherein the at least one crosslinker has a vinyl group capable of undergoing free radical polymerization.

13. The composition of claim 12, wherein the at least one crosslinking agent having a vinyl group capable of undergoing free radical polymerization comprises a multifunctional polyethylene glycol acrylate or a hydrophilic urethane acrylate.

14. 12. The composition of claim 11, wherein the at least one crosslinker has moieties capable of reacting with carboxy, alcohol, epoxy, carbonyl, or amine functional groups.

15. 15. The composition of claim 14, wherein the moieties capable of reacting with the carboxy, alcohol, epoxy, carbonyl, or amine functional groups include carbodiimides, isocyanates, azides, oxazolines, amines, hydrazides, silanes, epoxies, melamines, and other amino crosslinkers.

16. 10. The composition of claim 1 further comprising at least one photoinitiator comprising a phosphine oxide, a phenone, an azo initiator, a peroxide, or a benzoyl.

17. 17. The composition of claim 16, wherein the phosphine oxide comprises 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the phenone comprises 2-hydroxy-2-methylpropiophenone or benzophenone, azobisisobutyronitrile, the peroxide comprises benzoyl peroxide, and the benzoyl comprises 2,2-dimethoxy-1,2-diphenyl-ethan-1-one.

18. 10. The composition of claim 1, further comprising at least one additive that aids in the adhesion, crosslinking, film formation, anti-freeze, mechanical or rheological properties of the anti-fog material.

19. 19. The composition of claim 18, wherein the at least one additive that aids adhesion comprises (3-aminopropyl)triethoxysilane or polyethyleneimine.

20. 20. The composition of claim 18, wherein the at least one additive that aids in anti-freeze properties comprises glycerol, ethylene glycol, propylene glycol, or polyethylene glycol.

21. 20. The composition of claim 18, wherein the at least one additive that aids in mechanical properties comprises at least one of nanoparticles or polymeric resin.

22. 22. The composition of claim 21, wherein the at least one type of nanoparticle comprises silica nanoparticles, alumina nanoparticles, cellulose nanoparticles, or other inorganic fillers.

23. 22. The composition of claim 21, wherein the at least one polymeric resin comprises polyurethane, polyacrylate, polymethacrylate, polystyrene, polyethylene, polypropylene, paraffin wax, natural wax, or a combination thereof.

24. 20. The composition of claim 18, wherein the at least one additive that aids in film formation comprises a Triton, Tween, sodium dodecyl sulfate, or cetyltrimethylammonium bromide surfactant, a dispersant, a styrene maleic acid copolymer, a leveling agent, or a silicone and / or polyether modified polyacrylate.

25. The composition of claim 1 further comprising a carrier solvent comprising water, a volatile alcohol, a volatile ketone, a volatile ether, and a volatile amine.

26. 1. An anti-fogging material comprising a zwitterion-doped hydrogel, said zwitterion-doped hydrogel comprising: charged monomeric residues, at least a portion of which comprise zwitterionic monomeric residues; uncharged hydrophilic monomer residues; and at least one crosslinker residue Including, The anti-fog material exhibits a delta haze value of less than 5% when exposed to fog conditions.

27. A coated article comprising: a substrate and an anti-fog coating; The anti-fog coating comprises: a hydrogel doped with zwitterions; The zwitterion-doped hydrogel comprises: charged monomeric residues, at least a portion of which comprise zwitterionic monomeric residues; uncharged hydrophilic monomer residues; and at least one crosslinker residue Including, The coated article, when exposed to hazy conditions, exhibits a delta haze value of less than 5%.

28. 1. A method for making a surface of a substrate less prone to fogging, comprising: charged monomeric residues, at least in part comprising zwitterionic monomeric residues; uncharged hydrophilic monomer residues; and at least one crosslinker residue applying a zwitterion-doped hydrogel to the surface of the substrate, comprising: Including, The method, wherein the hydrogel exhibits a delta haze value of less than 5% when exposed to hazy conditions.

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