DESC:Field of Invention:
The present invention provides an anti-fog coating formulation as at least a two part formulation preferably adapted to provide a transparent coating on substrates including transparent plastic like substrates, glass or glass like substrates with permanent anti fogging property.
Background Art:
Glass and plastics materials are used for Helmets, Vehicle headlight, windows, mirrors, lenses, goggles, eyeglasses, ski goggles, binoculars, analytical and medical instruments (infrared microscopes) 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 and reduces the optical transmission / visibility of transparent surfaces. Generally two fundamental approaches are there to combat hazy water condensation. Controlling the temperature and humidity is one of the approaches wherein if the device is heated enough or purged with air, the moisture cannot condense on the surface. In spite of being effective these approaches consume energy and are expensive and have limited applicability for common glass like plastic substrates or glass. The other approach is to use anti-fog coatings. Anti-fog coatings can absorb, spread and release moisture simultaneously preventing hazy water condensation by spreading water droplets to thin water membrane maintaining the optical clarity. Obviously, this is a better approach, because anti-fog coatings 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 and glass surface(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 relatively high 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, sorbitol polyglycide 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 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 surface layer and thereby a high level of hydrophilicity 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, EP0444864A2 describes ultraviolet curing and anti-fogging amide based polymeric agent, U.S. Pat. No. 5,116,442 describes a polyethylene oxide system, US5116442A describes transparent polyurethane film with energy-absorbing and antifogging properties, 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, US4590117A describes a transparent material having an antireflective coating comprising at least two layers, an inner layer containing a compound of Ti, Al or Zi, and an outer layer containing an organic silicon compound also including a surfactant to provide for antifogging properties, U.S. Pat. No. 4,478,909 describes a poly(vinyl alcohol)-silica system, US5134021A teaches anti-fogging film having a multilayer structure comprised of at least two layers of a cured film formed on a substrate which cured film contains as main components polyvinyl alcohol and colloidal silica, 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, EP 3208319A1 discloses amphiphilic copolymers with mixed functionalities comprising: a. repeating monomeric units comprising a pendant zwitterionic moiety; b) repeating monomeric units comprising a pendant group comprising a fluorine-containing group and at least one heteroatom; and c) optionally, secondary repeating monomeric units comprising a pendant group comprising a functional group selected from the group consisting of phosphate groups, phosphonate groups, sulfonate groups, alkoxysilane groups, carboxylate groups etc.
WO2017018146A1 prepared curable composition containing at least one multifunctional (meth)acrylamide compound and multifunctional monomeric compound and at least one betaine monomer wherein heat (40-120 oC) or light (low, medium, or high pressure mercury lamp, metal halide lamp, deep ultraviolet light etc.) is essential for complete curing and providing anti-fogging property.
Metwally Ezzat et al. have reported (Issue 66, 2016, RSC Advances) Zwitterionic polymer brush coatings with excellent anti-fog and anti-frost properties involving poly(sulfobetaine methacrylate) which was prepared by surface initiated atom transfer radical polymerization. However, the application methods for these coatings involve multiple steps and pre-treatment of the substrate is necessary, to activate the surface and only applicable for ceramic substrate.
Although the above mentioned 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 designs have 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 designs also have inefficient fabrication processes, e.g., a long coat curing time etc.
Reference is made to co-pending application no. 201821032749 dt. 31.08.2018 providing for two-component transparent hydrophilic coating formulation comprising select components of sulfo-group-containing acrylic hydrophilic copolymer and as the second component either silane reagents bearing reactive groups (for glass) or hydrophilic aliphatic polyisocyanates (for glass or plastic) favouring permanent anti fogging property that is also curable at room temperature.
While the above co-pending application tends to address the longstanding issues in the art there is still a need to explore for further formulations that would provide for the anti-fogging benefit and at the same time would favour good film formation property, water washout resistance property coupled with the provision of easy application.

Objectives of the invention:
It is thus the basic object of the present advancement to provide for anti-fog coatings and formulation thereof which would be useful for various commercial applications and thus such anti-fog coating should possess high clarity, be able to absorb and release moisture simultaneously and be able to resist water condensation in variety of surrounding environmental conditions.
Another objective of the present advancement is to provide a coating formulation at least in two parts/ packs that would be transparent and hydrophilic favouring coating or compositions thereof with permanent anti fogging property on transparent plastic like substrates and glass or glass like substrates.
Yet another objective of the present advancement is to provide for at least a two-pack transparent hydrophilic coating formulation curable both at room temperature and at elevated temperature having permanent anti fogging property on substrates including glass or glass like substrates, transparent plastic like substrates wherein said formulation would provide for a good film formation property.
Another objective of the present advancement is to provide for said coating formulation in at least two parts/pack as transparent hydrophilic coating formulation that would be curable both at room temperature and elevated temperatures favouring permanent anti fogging property on substrates including glass or glass like substrates, transparent plastic like substrates wherein said composition would favour good film formation property, water washout resistance property and would also favour easy application including through spray, flow, roller.
According to further objective of the present advancement is to provide for said coating formulation in at least in two parts which when applied on glass or glass like substrates would be highly transparent with good film formation ability and water washout resistance property and would be also stable in hot and cold weather conditions.
According to still further objective of the present advancement is to provide for a coating formulation in at least two parts/packs curable both at room temperature and also at elevated temperature having permanent anti fogging property on substrates including glass or glass like substrates and transparent plastic and plastic like substrates and comprising copolymer including hydrophilic functional groups like –OH, -NR2 and –CO2R’.
Summary of the Invention:
Thus according to the basic aspect of the present invention there is provided an anti-fog coating formulation comprising zwitterionic polymers of cyclic ester and -NR2 functional group based acrylate copolymer, said acrylate copolymer being a copolymer of hydrophobic, hydrophilic, and active -NR2 functional group based monomer/s.
Preferably said anti-fog coating formulation as a solvent based formulation in parts s provided comprising
said acrylate copolymer being thermoplastic polymer comprises both hydrophobic and hydrophilic functional group based monomers and includes –OH, -NR2 and –CO2R’;
said cyclic ester/ lactone;
adapted to provide improved transparent coats/films on substrates with improved film forming property together having permanent anti-fogging effect that absorbs and releases moisture simultaneously and are able to resist water condensation in variety of surrounding environmental conditions.
More preferably said anti-fog coating formulation is provided comprising
Said -NMe2 group based acrylate copolymer in amounts of 5-25 wt.% preferably 10 wt.%
Said cyclic ester in amounts of 0.6-5 wt.% preferably 2 wt.%;
Said Solvent in amounts of 40-90 wt.% preferably 88 wt.%.
According to another preferred aspect of the present invention there is provided said anti-fog coating formulation wherein said zwitterionic polymer being a reaction product of lactone and -NR2 group based acrylate copolymer is obtained of free radical copolymerization of –CO2R’,–OH, and -NR2 based methacrylate monomers in mole proportion range of 0.14-0.18, 0.18-0.25, 0.08-0.1 and further reacted with cyclic ester/lactone; and
wherein for said –NR2 group based monomers R=alkyl including C=1-5 preferably C=1-3 methyl, ethyl, propyl, wherein for said –CO2R’ group based monomers R’=alkyl including C=1-5 preferably methyl, ethyl, propyl more preferably methyl, ethyl.
Preferably said anti-fog coating formulation is provided wherein said zwitterionic polymers being a reaction product of lactone and -NMe2 group based methacrylate copolymer is obtained of free radical copolymerization of preferably 24-31 wt.% methyl methacrylate (MMA), 41-55 wt.% 2-hydroxyethyl methacrylate (HEMA), 20-28 wt.% 2-(dimethylamino) ethyl methacrylate (DMAEMA), and further reacted with cyclic lactone, and has molecular weight ranging from 6000 to 2000 preferably in the range of 8000 to 10500 and polydispersity in the range of 3.5 to 10.5 preferably 4.5-8.4.

According to yet another preferred aspect of the present invention there is provided said anti-fog coating formulation wherein said cyclic ester/ lactone includes 1, 3 propane sultone, 3-Hydroxyl-1-propane sulfonic acid sulfone, 1,4-Butanesultone, 1,8-Naphthosultone, a-acetolactone, ß-propiolactone, caprolactone, ?-butyrolactone, and d-valerolactone or mixtures thereof.
Preferably said anti-fog coating formulation is provided wherein said acrylate monomers include hydrophobic and hydrophilic functional group based polymerizable monomers and includes 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritol caprolactone hexa acrylate, ethoxylated trimethyl propane triacrylate, ethoxylated (4) pentaerythritol tetra acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate ethoxylated trimethylol propane trisacrylate, 4-tert-butyl cyclohexyl acrylate, glycidyl vinyl benzyl ether, N,N-diglycidyl aniline, methyl methacrylate, ethyl methacrylate, bis (4-glycidyloxyphenyl) methane, 2-(sulfoxy) ethyl methacrylate ammonium salt, 2-(acryloyloxy) ethyltrimethyl ammonium chloride.
According to yet another preferred aspect of the present invention there is provided said anti-fog coating formulation wherein said solvents include isopropyl alcohol, tetrahydrofuran, diacetone alcohol, n-butanol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Ethanol, Dimethyl formamide, methyl ethyl ketone, ethyl acetate and normal butyl acetate, and is preferably isopropyl alcohol, n-butanol, toluene, ethyl cellusolve, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate.
According to another aspect of the present invention there is provided a process to manufacture said anti-fog coating formulation providing both hydrophilic and hydrophobic group based acrylate monomers including –OH, -NR2 and –CO2R’ in solvent and polymerizing in the presence of thermal-polymerization initiator;
Providing cyclic ester/lactone and obtaining zwitterionic polymer based formulation therefrom.
Preferably in said process to manufacture said anti-fog coating formulation wherein polymerizing is done in the 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.
More preferably in said process to manufacture said anti-fog coating formulation comprises providing
i. solvent solution preferably IPA solution of -NMe2 group based acrylate copolymer in 5-25 wt%;
ii. 0.6-5 wt% cyclic ester and stirring adding balance solvent and applying on glass or glass like polymeric substrates to yield permanent anti-fog coating with good film formation on said substrates.
Another aspect of the present advancement is to provide for anti-fog coating formulation involving polymer comprising of hydrophilic functional groups like –OH, -NR2 and –CO2R’ preferably obtained of via free radical copolymerization of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA).
The select monomers of the present advancement comprises hydrophobic methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), that thereby would generate a copolymer with good stability in water, having favourable interaction with the surface of PC/glass, and would be easily modifiable post polymerization to provide for the above discussed desired properties.

Detailed Description of the invention:
As discussed hereinbefore the present invention relates to a permanent anti-fog coating material using simple methacrylic copolymer. The copolymer comprises both hydrophobic, hydrophilic monomers and active -NR2 preferably -NMe2 group containing monomer important for post polymerization modification of the copolymer and at the same time with excellent film forming property. The preferred -NMe2 groups of the copolymer is further reactive with 1, 3 propane sultone (PS) which is a cyclic lactone type moiety and with –NMe2 yield zwitterionic copolymers, which exhibits excellent anti-fog property. The newly developed coating system is a thermoplastic polymer based stable and transparent coating. The hydrophilic property appears due to hydrophilic zwitterionic group and the anti-fog coating formulation attained thereof comprises of a formulation in at least in two parts/ packs, which provides for hydrophilic coating that is hydrophilic both at room temperature and elevated temperature and is curable to enable anti fogging effect both at high and low temperature with good film forming ability, excellent water wash out resistance property which is also stable in hot and cold weather conditions.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed that should not be construed to limit the scope of the present invention. The advancement according to the present invention is discussed in further detail in relation to the following non-limiting exemplary illustrations wherein:

BRIEF DESCRIPTION OF FIGURES:
Figure 1: Synthesis of random copolymer by free radical polymerization technique and in-situ post polymerization modification of the copolymer by PS.
Figure 2: 1H-NMR spectra of random copolymer (P1).
Figure 3: FT-IR spectra of random copolymer and PS modified copolymer.
Figure 4: Digital image of anti-fog property under hot fog condition.
Figure 5: Digital image of anti-fog property under cold fog condition (both for PC and glass).
The anti-fog coating of the present advancement according to an embodiment can be obtained following the steps as discussed hereunder:
Preparation of hydrophilic zwitterionic polymer for anti-fog formulation
An acrylic copolymer is prepared in the first step wherein reaction of different acrylic monomers containing hydrophilic and hydrophobic moieties results in enhanced stable film formation properties.
Step (a.):Preparation of acrylic copolymers
Polymers are synthesised by polymerizing hydrophilic monomers containing terminal or branched hydrophilic functional groups, such as, amine, hydroxyl 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 monomers include 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritol caprolactone hexa acrylate, ethoxylated trimethyl propane triacrylate, ethoxylated (4) pentaerythritol tetra acrylate, 2-(dimethylamino) ethyl methacrylate, 2-(diethylamino)ethyl methacrylate 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, 2-(acryloyloxy) ethyltrimethyl ammonium chloride 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 further stirring 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 (cyclohexane-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, tetrahydrofuran, diacetone alcohol, n-butanol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Ethanol, 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 copolymer obtained from step a) is mixed with cyclic esters moiety.
Water contact angle obtained is within the range of 10-40 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:
Example-I
Synthesis of active -NMe2-group-containing acrylic hydrophilic random copolymer (polymer-1):
The hydrophilic copolymer (polymer-1) was synthesized via free radical polymerization of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The monomers were used according to the following ratio; 24 wt% MMA, 55wt% HEMA, 20wt% 2-(dimethylamino) ethyl methacrylate. N-Butanol 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 random copolymers, the functional groups available for hydrophilic properties were –OH and –NMe2. The number average molecular weight (Mn) of the synthesized polymer was around 12000.
The –NR2 group based monomers tested were from the group of R=alkyl including C=1-5 preferably C=1-3 methyl, ethyl, propyl, wherein for said -CO2R’ group based monomers tested R’=alkyl including C=1-5 preferably methyl, ethyl, propyl more preferably methyl, ethyl, that provided for positive results. Same for Polymer-2 below.
Example-II
Synthesis of active -NMe2-group-containing acrylic hydrophilic copolymer (polymer-2):
The 2nd -NMe2-group-containing acrylic hydrophilic copolymer (polymer-2) were synthesized via free radical polymerization of 31wt% MMA, 41wt% HEMA, 28wt% 2-(dimethylamino) ethyl methacrylate. N-Butanol used as solvent. Di-tert-butyl peroxide was used as the radical initiator. The polymerization reaction was performed under reflux and stirring conditions. In this random copolymer, the functional groups available for hydrophilic properties were –OH and -NMe2. The number average molecular weight (Mn) of the synthesized polymer was around 10000.
If anyone of the required functional groups are absent in the copolymer the anti-fog property, surface adhesion and coating stability in presence of water would not be reached up to desired level.
Table 1: Synthesis of random copolymers (P1 and P2) with number average molecular weight (Mn) and PDI calculated by GPC
Entry MMA
(mol) HEMA
(mol) DMAEMA
(mol) Mn
GPC PDI
Polymer 1 (P1) 0.14 0.25 0.08 8000 8.4
Polymer 2 (P2) 0.18 0.18 0.1 10500 4.5

Preferably the mole proportions of three monomers (MMA, HEMA and DMAEMA) is also very important to achieve the desired anti-fog, surface adhesion and coating stability in water. Otherwise, the anti-fog property, surface adhesion and coating stability would not be reached up to the desired level.
Application of the polymers:
Example-III (formulation for glass and transparent plastic substrate)
The synthesized polymers (polymer-1, and/or polymer-2) are formulated for the application on the glass. In the final formulation, 5-25 wt% including either or both the synthesized polymers, 0.6-5 wt% cyclic ester, such as, 3-Hydroxyl-1-propane sulfonic acid sulfone, 1,4-Butanesultone, 1,8-Naphthosultone, a-acetolactone, ß-propiolactone, caprolactone, ?-butyrolactone, and d-valerolactoneor mixtures thereof 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). The –NMe2 groups of the copolymer can react with cyclic ester and produces zwitterionic copolymer, which exhibits excellent hydrophilicity.
Table-I
Polymer Amnt.
(%) 1,3-Propane sultone (%) Solvent IPA (%) Contact angle Antifog Pencil Hardness Adhesion test Peel test (glass)
Polymer-1 10 2 88 = 20 yes H No Peeling
Polymer-2 10 2 88 = 20 yes H No peeling
Polymer-3 (comparative) 10 0.5 89.5 = 40 Low H Peel off

Considering said -NMe2 group based acrylate copolymer (polymer 1) & polymer (2) is in amounts of 5-25 wt.% preferably 10 wt.%
Said cyclic ester in amounts of 0.6-5 wt.% preferably 2 wt.%;
Said Solvent in amounts of 40-90 wt.% preferably 88 wt.%.
It is thus possible by way of the present advancement to provide for anti-fog coating formulation at least in two parts/ packs that is hydrophilic both at room temperature and elevated temperature and is curable to favour coatings with anti-fogging benefits both at high and low temperature with excellent water wash out resistance property.
,CLAIMS:We Claim
1. Anti-fog coating formulation comprising zwitterionic polymers of cyclic ester and-NR2 functional group based acrylate copolymer, said acrylate copolymer being a copolymer of hydrophobic, hydrophilic, and active -NR2 functional group based monomer/s.
2. Anti-fog coating formulation as claimed in claim 1 as a solvent based formulation in parts comprising
said acrylate copolymer being thermoplastic polymer comprises both hydrophobic and hydrophilic functional group based monomers and includes –OH, -NR2 and –CO2R’;
said cyclic ester/ lactone;
adapted to provide improved transparent coats/films on substrates with improved film forming property together having permanent anti-fogging effect that absorbs and releases moisture simultaneously and are able to resist water condensation in variety of surrounding environmental conditions.
3. Anti-fog coating formulation as claimed in claims 1-2 comprising
Said -NMe2 group based acrylate copolymer in amounts of 5-25 wt.% preferably 10 wt.%
Said cyclic ester in amounts of 0.6-5 wt.% preferably 2 wt.%;
Said Solvent in amounts of 40-90 wt.% preferably 88 wt.%.
4. Anti-fog coating formulation as claimed in claims 1-3 wherein said zwitterionic polymer being a reaction product of lactone and -NR2 group based acrylate copolymer is obtained of free radical copolymerization of –CO2R’,–OH, and -NR2 based methacrylate monomers in mole proportion range of 0.14-0.18, 0.18-0.25, 0.08-0.1 and further reacted with cyclic ester/lactone; and
wherein for said –NR2 group based monomers R=alkyl including C=1-5 preferably C=1-3 methyl, ethyl, propyl, wherein for said –CO2R’ group based monomers R’=alkyl including C=1-5 preferably methyl, ethyl, propyl more prferably methyl, ethyl.
5. Anti-fog coating formulation as claimed in claims 1-4 wherein said zwitterionic polymers being a reaction product of lactone and -NMe2 group based methacrylate copolymer is obtained of free radical copolymerization of preferably 24-31 wt.% methyl methacrylate (MMA), 41-55 wt.% 2-hydroxyethyl methacrylate (HEMA), 20-28 wt.% 2-(dimethylamino) ethyl methacrylate (DMAEMA), and further reacted with cyclic lactone, and has molecular weight ranging from 6000 to 2000 preferably in the range of 8000 to 10500 and polydispersity in the range of 3.5 to 10.5 preferably 4.5-8.4.
6. Anti-fog coating formulation as claimed in claims 1-5 wherein said cyclic ester/ lactone includes 1, 3 propane sultone, 3-Hydroxyl-1-propane sulfonic acid sulfone, 1, 4-Butanesultone, 1, 8-Naphthosultone, a-acetolactone, ß-propiolactone, caprolactone, ?-butyrolactone, and d-valerolactone or mixtures thereof.
7. Anti-fog coating formulation as claimed in claims 1-6 wherein said acrylate monomers include hydrophobic and hydrophilic functional group based polymerizable monomers and includes 2-hydroxyethylmethacrylate (2-HEMA), 2-hydroxypropylacrylate (2-HPA), dipentaerythritol caprolactone hexa acrylate, ethoxylated trimethyl propane triacrylate, ethoxylated (4) pentaerythritol tetra acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate ethoxylated trimethylol propane trisacrylate, 4-tert-butyl cyclohexyl acrylate, glycidyl vinyl benzyl ether, N,N-diglycidyl aniline, methyl methacrylate, ethyl methacrylate, bis(4-glycidyloxyphenyl)methane, 2-(sulfoxy)ethyl methacrylate ammonium salt, 2-(acryloyloxy) ethyltrimethyl ammonium chloride.
8. Anti-fog coating formulation as claimed in claims 1-7 wherein said solvents include isopropyl alcohol, tetrahydrofuran, diacetone alcohol, n-butanol, toluene, xylene, ethyl cellusolve, butyl cellusolve, methyl isobutyl ketone, Ethanol, Dimethyl formamide, methyl ethyl ketone, ethyl acetate and normal butyl acetate, and is preferably isopropyl alcohol, n-butanol, toluene, ethyl cellusolve, methyl isobutyl ketone, methyl ethyl ketone and ethyl acetate.
9. A process to manufacture said anti-fog coating formulation as claimed in claims 1-8 providing both hydrophilic and hydrophobic group based acrylate monomers including –OH, -NR2 and –CO2R’ in solvent and polymerizing in the presence of thermal-polymerization initiator;
Providing cyclic ester/lactone and obtaining zwitterionic polymer based formulation therefrom.
10. A process to manufacture said anti-fog coating formulation as claimed in claims 1-9 wherein polymerizing is done in the 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.
11. A process to manufacture said anti-fog coating formulation as claimed in claims 1-10 comprising providing
i. solvent solution preferably IPA solution of -NMe2 group based acrylate copolymer in 5-25 wt%;
ii. 0.6-5 wt% cyclic ester and stirring adding balance solvent and applying on glass or glass like polymeric substrates to yield permanent anti-fog coating with good film formation on said substrates.

Dated this the 5th Day of December, 2019 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/ PA-199