DESC:Field of Invention:
The present advancement provides for anti-fogging room temperature curable hydrophilic coating formulation/composition having two component system which preferably provides for transparent anti-fog coating with selectively balanced hydrophilicity and having permanent anti fogging property on transparent plastic like substrates, glass or glass like substrates, and polymer composites attained thereof including said glass and/ or plastic like substrates.
Background Art:
Glass and plastics materials used for Helmets, Vehicle headlight, windows, mirrors, lenses, goggles, and facial masks or shields become foggy when they are exposed to high humidity and temperature, or used at interfacial boundaries with a large difference in temperature or humidity. Fog is caused by the condensation of moisture on the surface of plastic substrates or glass. Generally two fundamental approaches are there to combat hazy water condensation. Controlling the temperature and humidity is one of the approacheswherein if the device is heated enough or purged with dry air,the moisture cannot condense on the surface. Inspite of being effective these approaches consume energy and are expensive and have limited applicability for common glass and glass like substrate and plastic and plastic like substrates. The other approach is to use anti-fog coatings. Anti-fog coatings can absorb, spread and release moisture simultaneously preventing hazy watercondensation maintaining the optical clarity. Obviously, this is a better approach, because anti-fogcoatings are cheaper and consume no energy to operate and could be utilized universally. A coating which is transparent can absorb, spread and release moisture and provide an anti-fog property under a variety of environmental conditions when applied on transparent plastic and glass substrates is of great importance in the present scenario.

Different material approaches are known for permanent hydrophilization of surfaces. One such approach is the use of hydrophilic polymers and copolymers as a coating material for plastic surfaces and glass (e.g. ski goggles). Transparent anti-fog coatings for polycarbonate surfaces, based on polyurethanes, are known. Polyurethanes can be provided with relatively high surface energies, by means of polar structures. This results in relativelyhigh water absorption of the polymer, which leads to adsorbed water layers on the surface, i.e. hydrophilic behaviour. But the high water absorption of hydrophilic polymers frequently results in loosening of the adhesion of the layers, in long-term.
Adhesion promotion agents based on silanes are used to improve the adhesion of hydrophilic coating materials. For example, a coating material based on acrylic acid, polyethylene glycol monomethyl acrylate, sorbitolpolyglycide ether with silane coupling reagents is known from JP 62129367 A1, as an anti-fog coating material for plastics and glass. The transparent layers demonstrate clear swelling, i.e. softening of the material, after being stored in water at 60 ºC. A hydroxyethyl acrylate/hydroxyethyl methacrylate/vinyl pyrrolidone copolymer, using silane adhesion-promoting agents (amino alkyl-functionalized, methacryl-functionalized, vinyl-functionalized, and mercapto-functionalized alkoxy silanes) are described in JP 54119599 A1, for the production of hydrophilic plastic surfaces. Comparable materials having hydrophilic polyoxyethylene structures in a methacrylate/hydroxyethyl methacrylate matrix having methacryl-modified trialkoxy silanes as adhesion-promoting agents are described in JP 2169651 (US20040237833A1) as hydrophilic coating materials for plastic films, for applications in the agricultural sector. Mechanical properties, such as, scratch resistance and friction wear resistance of the silicone based films are not discussed there.
Another fundamental approach to the hydrophilization of surfaces is building ionic or non-ionic surfactants into coating materials having polar structure elements. On one hand, ionic surfactants, in particular, can be chemically bonded to appropriate polymers, and produce additional highly polar i.e. hydrophilic centres, by means of the "hydrophilic head"; on the other hand, non-ionic surfactants can be built in, which accumulate on the interface with the air, because of thermodynamic equilibria, whereby extremely high concentrations of hydrophilic end groups of the surfactants are concentrated at the surfacelayer and thereby a high level of hydrophilia is achieved (DE2068494A1). When using non-ionic surfactants, these components possess a diffusion capacity, so that when contact with water occurs, the surfactants are dissolved out of the surface, whereby hydrophobic particles that are adsorbed on the surface are washed away with the surfactants. By means of diffusion, diffusible surfactant molecules are re-supplied to the surface, so that a "self-renewing" hydrophilic surface is formed as a result, until the reservoir of diffusible surfactant molecules in the bulk material has been used up. Coating materials made of dysfunctional aliphatic isocyanates (e.g. 1, 6-hexa-methylene diisocyanate, 2, 4-trimethyl-1, 6-hexamethylene diisocyanate, 3-isocyanatomethyl-3, 5, 5-trimethyl cyclohexyl isocyanate, etc.), as well as polyfunctional polyalcohols (polyester polyalcohols, polyether polyalcohols, etc.), and ionic or non-ionic surfactants (ethoxylated fatty alcohols) are described in DE2068494A1, whereby non-anionic surfactants are preferred because of their diffusibility. Such mixtures are particularly applied to transparent plastics, using usual coating techniques, and subsequently polymerized thermally. In addition, there is the possibility of applying and curing the polymer layers without dissolved surfactants, and finally diffusing the surfactants in, in aqueous solution, at elevated temperature (approximately 90 ºC.), whereby this can be accelerated by means of external pressure. The layers based on polyurethane that are produced demonstrate anti-fog properties (DIN 4646, Part 8) and have improved scratch resistance and friction wear resistance of the surface, as compared with usual transparent layers (scattered light approximately 4% after 100 cycles Taber Abrader); this is attributable to a "self-healing effect" (viscous flow under load) of the elastic polymer.
Many designs have been proposed for this application. For example, U.S. Pat. No. 5,244,935 describes a UV curable amide polymer, U.S. Pat. No. 5,116,442 describes a polyethylene oxide system, U.S. Pat. No. 4,609,688 describes a crosslinked polyurethane system, U.S. Pat. No. 5,075,133 describes a crosslinked poly(vinyl alcohol) coating, U.S. Pat. No. 4,478,909 describes a poly(vinyl alcohol)-silica system, U.S. Pat. No. 4,127,682 describes a crosslinked poly(vinyl alcohol) coating, U.S. Pat. No. 4,467,073 describes a poly(vinyl pyrrolidone) based system, U.S. Pat. No. 3,933,407 describes an acrylic siloxane system, and U.S. Pat. No. 3,865,619 describes a crosslinked carboxylic acid-acrylic acid ester system.
Reference is invited to US 4,080,476teaching surface of optical substrate being coated with a polymerized monomer of the formula:

wherein R is selected from the group consisting ofstraight and branched alkane or alkylene of up to 10 carbon atoms, R is selected from the group consisting of hydrogen and lower alkyl, and R'’ is a monovalent cation. The polymer may be linear, an interpolymer, or a cross linked polymer. The polymeric coating is capable of permitting steam, fog, water vapor, etc. to permeate its matrix and render the coated optical substrate anti-fog when subjected to such conditions. Further teaches employing aminopropyltriethoxy silane as a separate coat to be applied on glass slides enabling non-fogging coatings. This prior art teaches insitu polymerization techniques on the transparent surface involving one monomer that makes insitu polymerization easier and does not teach any control on the molecular weight and Tg of the synthesized polymer before application as the antifog polymers and does not teach any adhesion characteristicson glass or plastic surfaces.
EP2522702A1 provides an anti-fog coating composition that rarely suffers from blushing when applied and dried even under high-humidity conditions and that can be heat-cured even at low temperature in a short time and form a coating film that exhibits excellent tight adhesion to a substrate and excellent heat resistance and anti-fog properties. The anti-fog coating composition comprises (A) a copolymer prepared from a monomer mixture of a monomer (A1), a monomer (A2) and a monomer (A3); (B) a basic compound such as amines; and (C) a surfactant such as anionic surfactants. The monomer (A1) is a vinyl monomer that has an N-methylol group or an N-alkoxymethylol group. The monomer (A2) is a vinyl monomer that has a sulfonic acid group. The monomer (A3) is an alkyl(meth)acrylate monomer. This prior art teaches incorporation of surfactants and the combination of monomers and organic bases and are distinct in also not involving silanes.
Progress in Organic Coatings 2014, 77, 4, 785-789DOI:10.1016/j.porgcoat.2014.01.001 teaches a series of UV curable hydrophilic acrylate polymers containing sulfonic acid group prepared via free radical copolymerization using 2-acrylamido-2-methyl propane sulfonic acid (AMPS) as hydrophilic monomer, which were used as prepolymers for anti-fog coatings. These UV-curable acrylate polymers were then mixed with reactive diluents and photoinitiator to form coating formulas. Various substrates were coated with these formulas and cured under UV exposure to obtain transparent coatings with good adhesion and hardness. The anti-fog properties of UV-cured coating were measured by contact angle test and anti-fog test. The results showed that the AMPS content in prepolymer had a great influence on the anti-fog properties of UV-cured coating but lacks the ease of application for applying on any sized or shaped glass or plastic surfaces. Not only the above, this prior art is also not directed to a copolymer that would not give hydrophilic property of the backbone chain, and, is also not directed to a combination of monomers directed to impart hydrophilic property, good filming property, water washout resistance property and at the same time reacting through bridging or itself to the surface to be coated and also does not teach a room temperature curable material that is advantageous to use over UV curable system.
Journal of Coatings Technology and Research January 2018, Volume 15, Issue 1, pp 149–158 teaches a dual-cure hydrophilic acrylate polymer was synthesized via radical polymerization with acrylic acid (AA), isophorone diisocyanate (IPDI), 2-acrylamide-2-methylpropane sulfonic acid (AMPS), hydroxyethyl acrylate (HEA), and 3-(trimethoxysilyl)propyl-2-methyl-2-methacrylate (MPS) as monomers, then used as prepolymer for antifog coating with tetraethylorthosilicate (TEOS) as a crosslinker. The prepolymer was mixed with crosslinking agent and photoinitiator to form coating formulas. With an increasing TEOS amount, the hardness, adhesion, water resistance, impact resistance, and thermal stability of the films were improved, at the expense of transparency; with increasing dosage of AMPS, the hydrophilicity of the film increased at the expense of water resistance. Optimum coating properties could be obtained when the amount of AMPS was 7% and that of TEOS was 5.5%. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed that some SiO2 microspheres were formed and microphase separation occurred between the macromolecular segments, yielding the excellent coating properties. This prior art is not directed to a select combination of monomers together with sulfonic acid based monomers to have a polymer backbone that is not too hydrophilic to resist wash away during the fogging condition and enables curing at room temperature for usefulness from application point of view by which the antifog copolymer could be entrapped so that it cannot be washed away by the accumulated water. Moreover, in this prior art reference, distinctively siloxane containing MPS monomer in the co-polymer backbone is incorporated, additionally, polymers were not neutralized implying that the -COOH and –SO3H groups mostly remains dissociated before the reaction with TEOS thereby increasing the chance of making the coating more hazy/cloudy by unwanted side reactions and minimizing the chances of obtaining good, clear and transparent coating on the glass or plastic like substances.

US20170233601 teaches anti-fog coating compositions, such as transparent polymeric materials, methods for forming coated transparent polymeric materials, and coated transparent polymeric materials and more particularly relates to epoxy-acrylate hybrid coating compositions to impart long-lasting anti-fog performance for transparent polymeric materials, methods for forming coated transparent polymeric materials using such coating compositions, and coated transparent polymeric materials with long-lasting anti-fog performance. However, epoxy-containing monomers for cationic polymerization and acrylates for radical polymerization and mixing both of them to get the epoxy-acrylate hybrid was employed wherein the hydrophilic nature of the coating was imparted with the help of surfactants which can be washed out easily and does not teach hydrophilicity to be imparted by the hydrophilic polymers which have more durability and film forming properties.

CN102924662A teaches anti-fog type ultraviolet light curing polyacrylate copolymer preparation of anti-fog type and involves2-acrylamide-2-methylpropanesulfonic acid, hydroxy acrylate and other monomers being subjected to solution free radical polymerization to obtain a sulfonic group-containing hydroxy acrylate copolymer (A1); then polyisocyanate reacts with monohydroxy acrylate to prepare unsaturated group-containing monoisocyanate (A2); and finally the unsaturated group-containing monoisocyanate (A2) is grafted to the sulfonic group-containing hydroxy acrylate copolymer (A1) to prepare the anti-fog type ultraviolet light curing polyacrylate copolymer. The copolymer while has excellent hydrophilic anti-fog performance, has the disadvantage of being UV curable with not much ease of application.

CN106752623Bis directed toa method for preparing a thermosetting polyacrylate anti-fog coating wherein a silane coupling agent based on modified acrylic resin, polyethylene glycols introduce hydrophilic monomer, a sulfonic acid group-containing hydrophilic monomer is a double bond, TEOS being curing agent formulation, the hydrolysis of the silane coupling agent with the hydroxyl group are condensed to form Si-O-Si bond curing, crosslinking although the majority of hydroxyl groups in the process dehydrated Si-O-Si, but still a large number of hydroxyl groups bonded failed to silanol the presence of (Si-OH) form. And because Si-O-Si segments of a low surface energy, shift to a process of curing the coating film surface Gan, micro phase separation structure is formed, also carries the non-bonded silanols migrate to the surface of the coating, further increasing the coating film hydrophilic. Given the limited because of the single film hardness after curing the tetraethyl orthosilicate, recycling the amine curing agent and the main chain of the epoxy groups of the reaction, further increasing the crosslinking density, enhances the hardness, water resistance and anti-scratch properties, anti-fogging hydrophilic resins prepared having good water resistance. While this prior art involves GMA as a monomer which contains an epoxy group within the copolymer it is very difficult to control the crosslinking density which is very import for stability as well as antifog property. It is important to mention that if crosslinking density is very high antifog property will be low. As it is a free radical polymerization the epoxy containing GMA monomer along with hydroxyl or sulphonic acid group containing monomer imparts gelling of the copolymerwhich is not useful for industrial purposes(US6552144BI; EP 2985301A1). Also this prior art incorporates siloxane containing MPS monomer and epoxy containing monomer in the acrylic co-polymer backbone which is tricky for the attributes required for suitable anti-fog coating and have not neutralized the –SO3H groups. This prior art has further reacted the synthesized polymer either with TEOS and triethylenetetramine mixture or with IPDI for the preparation of the final coating materials that increases the chance of making the coating more hazy/cloudy.

Although the above mentionedcompositions/designs have addressed some of the problems in the field, none provides a total solution to the anti-fog application. For example, most of the compositions/formulationshave low moisture absorptivity, long moisture release time, poor water and solvent resistance and cannot be used repeatedly due to poor water and low abrasion resistance possessed thereby. Further some of the compositions/formualtionsalso have inefficient fabrication processes, e.g., a long coat curing time etc.Hence a need in the art to provide for anti-fog coatings and formulations/compositions comprising the same that would take care of the above mentioned problems.
Objectives of the invention:
It is thus the basic object of the present invention to provide for anti-fog formulations/ compositions and coatings thereof that would be useful for variety of commercial applications in having high clarity, would be able to absorb and release moisture simultaneously and be able to resist water and conventional organic solvents, such as alcohols, alkylbenzenes (e.g., toluene), glycolethers (e.g., propyleneglycol monomethyl ether), and alkyl ketones (e.g., methyl ethyl ketone) etc.
Another object of the present invention is to provide for anti-fog formulations/compositions and coatings thereof that would be curable at room temperature and not require any UV curing and would have permanent anti-fogging property.
Yet another object of the present invention is to provide for said two-component transparent hydrophilic coating formulation/composition that would be curable at room temperature having permanent anti fogging property on glass or glass like substrates including plastics and would at the same time would not only have good film formation property but also good water washout resistance property and would be stable in both hot and cold weather conditions, together with providing for polymer composites including substrates coated with said coating.
Summary of the Invention:
Thus according to a basic aspect of the present invention there is provided anti-fogging room temperature curable hydrophilic coating formulation having two component system comprising
(a) 10-30 wt.% neutralized branched copolymers of Hydrophilic monomers comprising terminal or branched hydrophilic functional groups including amine, -OH, -SO3H, -COOH, &, Non-hydrophilic monomers;
(b) curing component comprising a mixture of 10-20 wt% epoxy silanes and 11-25 wt% aminosilanes OR about 4-30 wt% aliphatic and/or aromatic polyisocyanates.
Preferably in said anti-fogging room temperature curable hydrophilic coating formulation said neutralized branched copolymers comprises monomers methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acids in the range of 4-8 wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10 wt% AMPS, 1-4 wt% acrylic acid.
More preferably, in said anti-fogging room temperature curable hydrophilic coating formulation said neutralized branched copolymers has acid number in the range of 0-10 mg KOH/gm post neutralization, preferably 0 mg KOH/gm, and are attained of free radical polymerization of said monomers in solvent or mixtures thereof an is base neutralized; wherein said copolymer of average molecular weight (Mw) of said copolymer is in the range of 2,000 to 10,000 when attained of DMF solvent; and wherein said copolymer has weight average molecular weight (Mw) in the range of 10,000 to 30,000 when attained of DMF/Butanol in the ratio of 1: 10.
According to another preferred aspect of the present invention there is provided said anti-fogging room temperature curable hydrophilic coating formulation wherein said neutralized branched copolymers make available for hydrophilic properties functional groups including –OH, -COOH and –SO3H.
Preferably, said anti-fogging room temperature curable hydrophilic coating formulation is provided coatable on substrates including glass, glass like, plastic substrates and polymer composites attained thereof.

According to another aspect a process for preparing anti-fogging room temperature curable hydrophilic coating formulation is provided comprising the steps of
(a)(i). Providing Hydrophilic monomers containing terminal or branched hydrophilic functional groups including amine, hydroxyl, -SO3H, -COOH, & Non-hydrophilic monomers in solvents;
(a)(ii). subjecting the monomer mixture of step (i) to free radical polymerization by radical initiator preferably Di-tert-butyl peroxide and refluxing;
(a)(iii). neutralization of acidic groups of the resultant copolymer preferably with KOH or organic bases like 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene to obtain said copolymer therefrom; and formulating with
(b) curing component comprising a mixture of 10-20 wt% epoxy silanes and 11-25 wt% aminosilanes OR about4-30 wt% aliphatic and/ or aromatic polyisocyanates adapted for application on substrates to provide for anti-fogging effect.
Preferably, a process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation is provided wherein
Said step (a)(ii) comprises polymerizing said monomers in the presence of a thermal-polymerization initiator at a temperature ranging from 80°C to 140 °C over a time-period ranging from 10 to 120 min with stirring, and further stirring for a period ranging from 4 to 10 hrs.
According to yet another preferred aspect of the process for preparing of anti-fogging room temperature curable hydrophilic coating formulationwherein polymerizable organic monomers include 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritol caprolactone hexa acrylate, ethoxylated trimethylol propane triacrylate, ethoxylated (4) pentaerythritol tetraacrylate, ethoxylated trimethylol propane trisacrylate, 4-tert-butyl cyclohexyl acrylate, glycidyl vinyl benzyl ether, N,N-diglycidyl aniline, methyl methacrylate, ehthyl methacrylate, bis(4-glycidyloxyphenyl)methane, 2-(sulfoxy)ethyl methacrylate ammonium salt.
Preferably is said process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation said solvents include DMF, BuOH, isopropyl alcohol, diacetone alcohol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Dimethyl formamide, methyl ethyl ketone, ethyl acetate and normal butyl acetate, among which preferred are isopropyl alcohol, n-butanol, toluene, ethyl cellusolve, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate, more preferably DMF or BuOH or mixtures thereof, employed in amounts ranging from 40 to 90% by weight based on a total amount of the reactants.
According to yet another preferred aspect of the process said thermal-polymerization initiator, includes diallyl hexahydrophthalate, triallyl trimellitate or triallyl 1,2,4-benzenetricarboxylate, 2-cyano-2-propylazoformamide, 1,1’-azobis(cyclo- hexane-l-carbonitrile), 2,2'-azobis(2-amidino-propane)dihydrochloride,2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutylonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 4-methoxy(2,4-dimethylvaleronitrile), 2,2'azobis-(2-methylpropanenitrile) and a mixture thereof. Said thermal-polymerization initiator may be used in an amount ranging from 0.01 to 2% by weight based on the total amount of the reactants.
More preferably, in said process said curing component involving epoxy silanes include ?-Glycidoxypropyltrimethoxysilane, ?-Glycidoxypropyltriethoxysilane, 2-(3,4-Epoxycyclohexyl)-ethyltrimethoxysilane and aminosilanes include 3-aminopropyltriethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyl-trimethoxysilane; aliphatic and/or aromatic polyisocyanates include hexamethylene diisocyanate, Isophorone diisocyanate, Dicyclohexylmethane-4, 4’-diisocyanate, aliphatic polyisocyanate (N-75), 2, 4-Toluene diisocyanate, 4. 4’-Methylene di(phenylisocyanate), 1, 5-Naphthalene diisocyanate etc.
According to an aspect of the presentadvancementthe same is directed to providea two-component transparent hydrophilic coating formulation having permanent anti fogging property on transparent plastic like substrates and glass or glass like substrates wherein component one comprise sulfo-group-containing acrylic hydrophilic copolymer synthesized via free radical copolymerization and component two comprise either silane reagents bearing reactive groups (for glass) or hydrophilic aliphatic polyisocyanates (for glass or plastic) curable at room temperature.
According to another aspect of the present advancement to the same is directed to provide a two-component transparent hydrophilic coating formulation/composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the said composition comprises good film formation property.
According to yet further aspect of the presentadvancementthe same is directed to provide a two-component transparent hydrophilic coatingformulation/composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the said composition comprises with good film formation and water washout resistance property.
According to further aspect of the presentadvancementthere is provided a two-component transparent hydrophilic coating formulation/composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the said composition when applied on glass or glass like substrates is transparent.
According to yet another aspect of the present advancement there is provided for atwo-component transparent hydrophilic coating formulation/ composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the said compositionwhen applied on transparent plastic like substrates is transparent.
According to yet another aspect of the present advancement there is provided a two-component transparent hydrophilic coating formulation/composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the said composition comprises with good film formation and water washout resistance property is stable in hot and cold weather condition.
According to a further aspect of the present advancement there is provided for a two-component transparent hydrophilic coating formulation/ composition curable at room temperature having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the synthesized copolymer comprises hydrophilic functional groups like –OH, -COOH and –SO3H.
According to still further aspect of the present advancement there is provided for an anti-fog coating formulation involving polymer comprising of hydrophilic functional groups like –OH, -COOH and –SO3H will be synthesized via free radical copolymerization of methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acids.
It is thus the surprising finding of the present invention providing for two-component transparent hydrophilic coating formulation/composition coatable on substrates including glass or plastic substrates, also thereby providing for polymer composites thereof involving said substrates and coating thereon, which said coating formulation in involving select components are curable at room temperature, hence provides ease of application, does not require any UV curing, has permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein said formulation/composition comprises good film formation property, good water wash out resistance properties, is transparent, and is also stable in hot and cold weather condition.
Said two component transparent hydrophilic coating formulation/composition though in involving hydrophilic functional groups like –OH, -COOH and –SO3H in the copolymer have been neutralized to balance the hydrophilicity of the copolymer on one hand, and on the other hand, care is taken such that the backbone of the polymer is such that it is not too hydrophilic such that it does not resist the wash away during the fogging condition. However, the hydrophilicity was imparted by hydrophilic polymers which have more durability and film forming properties and at the same time is completely free from surfactants.
Added to the above, epoxy and amino silane containing compounds were employed for curing at room temperature for usefulness of application in which the antifog copolymer could be entrapped so that it does not wash away by the accumulated water.Alsosiloxane containing MPS monomer in the co-polymer backbone is avoided which is tricky for the present invention to reach to the desired properties.
Additionally, GMA as a monomer having epoxy group within the copolymer, is avoided in the present invention as then it becomes very difficult to control the crosslinking density important for stability as well as antifog property. It is important to mention that if crosslinking density is very high antifog property will be low. As it is a free radical polymerization the epoxy containing GMA monomer along with hydroxyl or sulphonic acid group containing monomer imparts gelling of the copolymer which is not useful for industrial use.

Detailed Description of the invention:
As discussed hereinbefore, the present invention provides for two component/ pack hydrophilic room temperature curable coating formulation having anti fogging effect at high and low temperature with excellent water wash out property in involving selective balanced hydrophilic property.The anti-fog coating of the advancement according to an embodiment can be obtained following the steps as discussed hereunder:
Step (a.): Preparation of hydrophilic Polymer
An acryliccopolymer is prepared in the first step wherein reaction ofdifferent acrylic monomers containing hydrophilic moieties with acrylic monomers having non-hydrophilic moieties results in enhanced stable film formation properties.
Preparation of acrylic polymers
Polymersaresynthesised by polymerizing hydrophilic monomerscontaining terminal or branched hydrophilic functional groups, such as, amine, hydroxyl and/or thiol group and non-hydrophilic monomers, in the presence of a thermal-polymerization initiator at a temperature ranging from 110°C to 140°C.
Examples of the polymerizable organic monomersinclude 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritolcaprolactonehexa acrylate, ethoxylated trimethylol propane triacrylate, ethoxylated (4) pentaerythritol tetraacrylate, ethoxylated trimethylol propane trisacrylate, 4-tert-butyl cyclohexyl acrylate, glycidyl vinyl benzyl ether, N,N-diglycidyl aniline, methyl methacrylate, ehthylmethacrylate, bis(4-glycidyloxyphenyl)methane, 2-(sulfoxy)ethyl methacrylate ammonium salt and the like.
The polymerization is conducted by dissolving acrylic monomers singularly or in combination in appropriate solvent, adding thereto a thermal-polymerization initiator dissolved in the same solvent and heating the resultant solution at a temperature ranging from 80°C to 140 °C over a time-period ranging from 10 to 120 min with stirring, and furtherstirring for a period ranging from 4 to 10 hrs.
As the thermal-polymerization initiator, any one of those known in the art may be used. Representative examples thereof include commercially available diallyl hexahydrophthalate, triallyl trimellitate or triallyl 1,2,4-benzenetricarboxylate, 2-cyano-2-propylazoformamide, 1,1’-azobis(cyclo- hexane-l-carbonitrile), 2,2'-azobis(2-amidino-propane)dihydrochloride,2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutylonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 4-methoxy(2,4-dimethylvaleronitrile),2,2'azobis-(2-methylpropanenitrile) and a mixture thereof. Said thermal-polymerization initiator may be used in an amount ranging from 0.01 to 2% by weight based on the total amount of the reactants.
The solvent which is used in the present invention may be any one of those known in the art, and representative examples thereof include isopropyl alcohol, diacetone alcohol, n-butanol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Dimethyl formamide, methyl ethyl ketone, ethyl acetate and normal butyl acetate, among which preferred are isopropyl alcohol, n-butanol, toluene, ethyl cellusolve, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate. Preferably, the solvent may be used in an amount ranging from 40 to 90% by weight based on a total amount of the reactants.
b)Preparation of coating substrate
The polymer obtained from step a) is mixed with isocyanate polymer precursor and other suitable curing catalyst.
Water contact angle obtained is within the range of 10-65 degree. The contact angles are further reduced after 1 minute of application.
The transparent surfaces which can be treated include glass surfaces such as automobile windows, e.g., the windshield, backlight and side windows, train windows, windows in buildings, e.g., apartments, homes, stores and office buildings, glass mirrors, eyeglasses including for example conventional eyeglasses, sunglasses, diving masks and ski glasses, camera lenses, microscope lenses, telescope lenses, binoculars and opera glasses, gun sights, drinking glasses (whereby the condensation occurring when iced drinks are placed therein is eliminated), transparent plastic surfaces including aeroplane windows, car and train windows, transparent films and containers used as coverings for packaged foods, e.g., meat packaged in a tray having a transparent top film of biaxially oriented irradiated polyethylene, reflecting metal surfaces such as chrome mirrors, etc.As used in the present specification and claims the term "automobile" is intended to cover cars, trucks, buses and all other automotive vehicles.
The transparent plastic having a fogging tendency can be PMMA and polycarbonate sheets as well as cellulose acetate, cellulose propionate, cellulose acetate-propionate, biaxially oriented polyethylene, biaxially oriented irradiated polyethylene (e.g., irradiated to 2-20 megarad), biaxially oriented polypropylene, biaxially oriented polystyrene, biaxially oriented styrene-acrylonitrile copolymer, biaxially oriented polyethylene terephthalate, biaxially oriented vinyl chloride, biaxially oriented vinylidene chloride polymers, e.g., vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, quench chilled polyethylene, quench chilled polypropylene and transparent fogging plastics made by other conventional techniques.
Examples of polymer synthesis:
General procedure for synthesis of polymers:
i. Different monomers with specific wt ratio (as mentioned in the examples) are taken into different solvents. (DMF or BuOH or a mixture of the two)
ii. Free radical polymerization with the aid of Di-tert-butyl peroxide as the radical initiator at refluxing with stirring condition for specified time
iii. The acidic groups of the resultant polymer were neutralized with either KOH or organic bases like 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene etc.
Example-I
Synthesis of sulfo-group-containing acrylic hydrophilic copolymer (copolymer-1):
The sulfo-group-containing acrylic hydrophilic copolymer (polymer-1) were synthesized via free radical copolymerization of methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acids. The monomers were used according to the following ratio; 4-8 wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10 wt% AMPS, 1-4 wt% acrylic acid. DMF was used as the solvent and Di-tert-butyl peroxide was used as the radical initiator. The polymerisation reaction was performed under refluxing and stirred conditions. In this branched copolymers, the functional groups available for hydrophilic properties were –OH, -COOH and –SO3H. The polymer was neutralized using organic and inorganic bases, such as, KOH, 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene etc. The weight average molecular weight (Mw) of the synthesized polymer was around 2,000 to 10,000.
Example-II
Synthesis of sulfo-group-containing acrylic hydrophilic copolymer (copolymer-2):
The 2nd sulfo-group-containing acrylic hydrophilic copolymer (polymer-2) were synthesized via free radical copolymerization of 4-8 wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10 wt% AMPS, 1-4 wt% acrylic acid. DMF and Butanol in the ratio of 1: 10 were used as solvent. Di-tert-butyl peroxide was used as the radical initiator. The polymerisation reaction was performed under reflux and stirring conditions. In this branched copolymers, the functional groups available for hydrophilic properties were –OH, -COOH and –SO3H. The polymer was neutralized using organic and inorganic bases, such as, KOH, 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene etc. The weight average molecular weight (Mw) of the synthesized polymer was around 10,000 to 30,000.
Example-III
Synthesis of sulfo-group-free acrylic hydrophilic copolymer (copolymer-3)
The sulfo-group-free acrylic hydrophilic copolymer (polymer-3) were synthesized via free radical copolymerization of 4-8 wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10wt% acrylic acid. N-butanol was used as solvent. Di-tert-butyl peroxide was used as the radical initiator. The polymerisation reaction was performed under refluxed and stirring conditions. In these branched copolymers, the functional groups available for hydrophilic properties were –OH, and –COOH.The polymer was neutralized using organic and inorganic bases, such as, KOH, 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene etc.The weight average molecular weight (Mw) of the synthesized polymer is around 60,000 to 90,000.
Example-IV
Synthesis of sulfo-group-containing acrylic hydrophilic copolymer (copolymer-4):
The sulfo-group-containing acrylic hydrophilic copolymer (polymer-4) were synthesized via free radical copolymerization of methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acids. The monomers were used according to the following ratio; 1-3wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10 wt% AMPS, 1-4 wt% acrylic acid. DMF was used as the solvent and Di-tert-butyl peroxide was used as the radical initiator. The polymerisation reaction was performed under refluxing and stirred conditions. In this branched copolymers, the functional groups available for hydrophilic properties were –OH, -COOH and –SO3H. The polymer was neutralized using organic and inorganic bases, such as, KOH, 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene etc.The weight average molecular weight (Mw) of the synthesized polymer was around 3,000 to 10,000.
All the synthesized co-polymers(PolymerI-IV) does not show or shows very little antifog properties when they are coated according to the coating formulationswithout being neutralized with the base. The observed contact angle in those cases are found to be in between 30-60.

Application of the polymers:
Example-V
Formulation for glass
The synthesized polymers (copolymer-1, copolymer-2,copolymer-3, copolymer-4, copolymer-5) wereformulated for the application on the glass. In the final formulation, 10-30 wt% synthesized polymers, 10-20 wt% epoxy silanes, such as, ?-Glycidoxypropyltrimethoxysilane, ?-Glycidoxypropyltriethoxysilane,2-(3,4-Epoxycyclohexyl)-ethyltrimethoxysilane and 11-25 wt% aminosilanes, such as, 3-aminopropyltriethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyl-trimethoxysilane were used. The final formulated materials were applied on the glass. Examples of formulations comprising each of the polymers with the related attributes are provided in Table(I).
Table-I
Polymer Amount(%) ?-Glycidoxy
propyl
Trimethoxy
silane (%) 3-amino
PropylTri
ethoxy
silane(%) Contact angle Antifog Pencil Hardness Cross cut adhesion
Polymer-1 20 12 11 = 20 yes H 5B
Polymer-2 20 12 11 = 20 yes H 5B
Polymer-3 20 12 11 = 20
Minimal H 5B
Polymer-4 20 12 11 = 20
Yes B 5B
Polymer-5 (without neutralisation of copolymers synthesised in Ex.I-IV 20 12 11 30-60 No H 5B

Example-VI
Formulation for glass and transparent polymer
The synthesized polymers were also formulated with the aliphatic polyisocyanate, such as the commercially available aliphatic or aromatic polyisocyanate such as, N75, Bayhydur XP 2547 etc. The final formulated materials were applied on the glass and transparent polymer sheets, such as, polycarbonate. Examples of formulations comprising each of the polymers with the related attributes are provided in Table(II).
Table-II
Polymer Amount(%) N75 Contact angle Antifog Pencil Hardness Cross Cut adhesion
Polymer-1 30 4 = 20 yes H 5B
Polymer-2 30 4 = 20 yes H 4B
Polymer-3 30 4 = 20 Minimal H 5B
Polymer-4 30 4 = 20 Yes B 5B
Polymer-5 (without neutralisation of copolymers synthesised in Ex.I-IV 30 4 60-70 No H 5B

Also aromatic isocyanates either alone or in combination with aliphatic isocyanates could provide the desired results when abided by the select wt.% range.
It was found that when wt.% of MMA in the co-polymer is less than 4% (as can be seen in the Example IV), the resultant film after coating formulation will be soft.
Added to the above, with incorporation of surfactants in the formulation lead to the formulation being washed out with time upon fogging and the antifog property kept decreasing over time.
The symbol’s H and B used in Pencil Hardness heading indicates the coating hardness according to ASTM D 3363 which indicates if the coating pass H rated pencil it is harder than which pass B. (H pass is more harder coating than B pass) and 5B used in Cross cut adhesion heading is according to ASTM D 3359 which indicates the adhesion between coating and the substrate.
It is thus possible by way of the present advancement to provide for a two-component transparent selectively balanced hydrophilic coating formulation/composition having permanent anti fogging property on glass or glass like substrates and transparent plastic like substrates wherein the component one comprise sulfo-group-containing acrylic hydrophilic copolymer synthesized via free radical copolymerization and component two comprise either silane reagents bearing reactive groups (for glass) or aliphatic and/or aromatic polyisocyanates (for glass and plastic) curable at room temperature.
,CLAIMS:We Claim:
1. Anti-fogging room temperature curable hydrophilic coating formulation having two component system comprising
(a) 10-30 wt.% neutralized branched copolymers of Hydrophilic monomers comprising terminal or branched hydrophilic functional groups including amine, -OH, -SO3H, -COOH, &,Non-hydrophilic monomers;
(b) curing component comprising a mixture of 10-20 wt% epoxy silanes and 11-25 wt% aminosilanes OR about 4-30 wt% aliphatic and/or aromatic polyisocyanates.
2. Anti-fogging room temperature curable hydrophilic coating formulation as claimed in claim 1 wherein said neutralized branched copolymers comprises monomers methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and acrylic acids in the range of 4-8 wt% MMA, 5-15 wt% HEMA, 6-11 wt% 2-EHA, 3-10 wt% AMPS, 1-4 wt% acrylic acid.
3. Anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 1 or 2 wherein said neutralized branched copolymers has acid number in the range of 0-10 mg KOH/gm post neutralization, preferably 0 mg KOH/gm, and are attained of free radical polymerization of said monomers in solvent or mixtures thereof an is base neutralized; wherein said copolymer of average molecular weight (Mw) of said copolymer is in the range of 2,000 to 10,000 when attained of DMF solvent; and wherein said copolymer has weight average molecular weight (Mw) in the range of 10,000 to 30,000 when attained of DMF/Butanol in the ratio of 1: 10.
4. Anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 1-3 wherein said neutralized branched copolymers providing for hydrophilic properties is based on functional groups including –OH, -COOH and –SO3H.
5. Anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 1-4 coatable on substrates including glass, glass like, plastic substrates and polymer composites attained thereof.
6. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 1-5 comprising the steps of
(a)(i). Providing Hydrophilic monomers containing terminal or branched hydrophilic functional groups including amine, hydroxyl, -SO3H, -COOH, & Non-hydrophilic monomers in solvents;
(a)(ii). subjecting the monomer mixture of step (i) to free radical polymerization by radical initiator preferably Di-tert-butyl peroxide and refluxing;
(a)(iii). neutralization of acidic groups of the resultant copolymer preferably with KOH or organic bases like 1,4-diazabicyclo[2.2.2]octane, 1,8-Diazabicyclo[5.4.0]undec-7-ene to obtain said copolymer therefrom; and formulating with
(b) curing component comprising a mixture of 10-20 wt% epoxy silanes and 11-25 wt% aminosilanes OR about 4-30 wt% aliphatic and/ or aromatic polyisocyanates adapted for application on substrates to provide for anti-fogging effect.
7. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claim 6 wherein
Said step (a)(ii) comprises polymerizing said monomers in the presence of a thermal-polymerization initiator at a temperature ranging from 80°C to 140 °C over a time-period ranging from 10 to 120 min with stirring, and further stirring for a period ranging from 4 to 10 hrs.
8. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 6 or 7 wherein polymerizable organic monomers include 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritol caprolactone hexa acrylate, ethoxylated trimethylol propane triacrylate, ethoxylated (4) pentaerythritol tetraacrylate, ethoxylated trimethylol propane trisacrylate, 4-tert-butyl cyclohexyl acrylate, glycidyl vinyl benzyl ether, N,N-diglycidyl aniline, methyl methacrylate, ehthyl methacrylate, bis(4-glycidyloxyphenyl)methane, 2-(sulfoxy)ethyl methacrylate ammonium salt.
9. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 6-8 wherein said solvents include DMF, BuOH, isopropyl alcohol, diacetone alcohol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Dimethyl formamide, methyl ethyl ketone, ethyl acetate and normal butyl acetate, among which preferred are isopropyl alcohol, n-butanol, toluene, ethyl cellusolve, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate, more preferably DMF or BuOH or mixtures thereof, employed in amounts ranging from 40 to 90% by weight based on a total amount of the reactants.
10. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 6-9 wherein said thermal-polymerization initiator, includes diallyl hexahydrophthalate, triallyl trimellitate or triallyl 1,2,4-benzenetricarboxylate, 2-cyano-2-propylazoformamide, 1,1’-azobis(cyclo- hexane-l-carbonitrile), 2,2'-azobis(2-amidino-propane)dihydrochloride,2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutylonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 4-methoxy(2,4-dimethylvaleronitrile), 2,2'azobis-(2-methylpropanenitrile) and a mixture thereof. Said thermal-polymerization initiator may be used in an amount ranging from 0.01 to 2% by weight based on the total amount of the reactants.
11. A process for the preparing of anti-fogging room temperature curable hydrophilic coating formulation as claimed in claims 6-10 wherein said curing component involving epoxy silanes include ?-Glycidoxypropyltrimethoxysilane, ?-Glycidoxypropyltriethoxysilane, 2-(3,4-Epoxycyclohexyl)-ethyltrimethoxysilane and aminosilanesinlcude 3-aminopropyltriethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyl-trimethoxysilane; aliphatic and/or aromatic polyisocyanates include hexamethylene diisocyanate, Isophorone diisocyanate, Dicyclohexylmethane-4, 4’-diisocyanate, aliphatic polyisocyanate (N-75), 2, 4-Toluene diisocyanate, 4. 4’-Methylene di(phenylisocyanate), 1, 5-Naphthalene diisocyanate.

Dated this the 30th day of August, 2019
Anjan Sen

Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199