Claims:We Claim:
1. Elastomeric pigmented architectural coating formulation facilitating early washout resistance, crack bridging ability and faster drying in humid conditions comprising
water insoluble anionic latex polymer having Tg less than 15 deg C;
and cationic amine modified polymer latexes;
wherein the ratio of the anionic and cationic polymer latex in the paint formulation is from 15:1 to 8:1 particularly suitable for exterior usage on concrete and masonry surfaces however can also be used in both high PVC and low PVC systems.

2. The Elastomeric pigmented architectural coating formulation as claimed in claim 1 that is free of methanol to reduce the toxic VOC content of the formulation and is fast drying, wherein the content of the amines functionality in the final paint is between 0.2% to 0.32% and backbone of the said anionic latex is crosslinked with selective dose of crosslinker (0.1-to 0.5 %) to impart dirt pick up resistance and both improved hydrophobic and wash-off properties.

3. The Elastomeric pigmented architectural coating formulation as claimed in claim 1-2 containing said water insoluble anionic latex polymer and cationic amine modified polymer latexes wherein
said water insoluble anionic latex includes acrylic or styrene acrylic latexes obtained of anionic surfactants; and
said amine functionalized latexes includes 3- dimethylaminopropyl methacrylamide modified latexes.

4. The Elastomeric pigmented architectural coating formulation as claimed in claim 1-3 having early shower resistance similar or superior than commercial paints under both lab condition and humidity chamber condition, lesser touch dry time and significantly higher crack bridging ability 0.1-0.5mm preferably more than 0.24 mm) @ 150 microns curing for 14 days.

5. The Elastomeric pigmented architectural coating formulation as claimed in claim 1-3 wherein
said water insoluble anionic latex includes acrylic or styrene acrylic latexes, obtained of emulsion polymerization by involving anionic surfactants; and
said amine functionalized latexes including 3-dimethylaminopropyl methacrylamide modified latexes are obtained of addition polymerization of ethylenically unsaturated monomers containing amine-functionality; polymerization of monomers which readily generate amines by hydrolysis; reactions of aziridines with carboxyl-containing polymers; reactions of polymers containing an enolic carbonyl group, e.g., acetoacetoxyethyl methacrylate ("AAEM"), and diamines; reactions of amines with epoxy-containing polymers; and reactions of amine with polymers of vinyl benzyl chloride particularly emulsion polymerization.

6. A method of preparing elastomeric pigmented architectural coating formulation as claimed in claims 1-5 comprising the steps of
Providing water insoluble anionic latex polymer having Tg less than 15 deg C;
Providing cationic amine modified polymer latexes in the ratio of 15:1 to 8:1; and
Mixing in mill base by involving balance ingredients of a paint formulation including 4% of ammonia to obtain said elastomeric paint formulations thereof.

7. The method of preparing elastomeric pigmented architectural coating formulation as claimed in claim 6 wherein providing water insoluble anionic latex polymer having Tg less than 15 deg C comprises the steps of
(i) Charging the reactor with surfactant and water to make a surfactant solution including Dowfax 2A1 in water;
(ii) Providing Pre-emulsion by dissolving Dowfax 2A1 (45% solution) (0.6-1.0%) and Atpol 5731non-ionic surfactant (0.1-0.5%), in water and adding methyl methacrylate (20-25%), butyl acrylate (23-28%), hydroxyl ethyl methacrylate (1-4%), optifilm enhancer 300 (0.8-2%), di-acetone acrylamide (0.1-0.5%), vinyl trimethoxysilane (0.2-0.4%), and methacrylic acid (0.5-1%)

(iii) Heating the reactor to 80 ?C followed by adding 5% of the pre-emulsion to initiate the seeding including adding potassium per sulfate and sodium bi carbonate solutions followed by adding the rest of the pre-emulsion after time gap of 15 mins which addition is done for a time period of 2 hr to 8 hrpreferably 4 hrs at 80 ?C;
(iv) post complete addition of pre-emulsion digestion catalyst is added and digestion continued for 45 minutes followed by cooling the reaction mass and adding additives at 45 ?C favouring water insoluble anionic latex polymer Latex B with Tg <15 OC and a minimum film forming temperature of >4 OC.

8. The method of preparing elastomeric pigmented architectural coating formulation as claimed in claims 6 or 7 wherein providing amine functionalized latexes comprises the steps of
(i) Charging the reactor with water, 2-amino-2-methyl-1-propanol (0.02-0.1%), Dowfax A 45 (0.1-0.5%) and non-ionic surfactant Tergitol 15-S-40 (0.5-2%).

(ii) providing pre-emulsion by emulsifying monomers including methyl methacrylate (14-18%), butyl acrylate (14-18%) and 2-(dimethyl amino) propyl methacrylamide (6-10%) in water in presence of tergitol 15-S-40 surfactant (1.5-3.5%) and 2-amino-2-methyl-1-propanol (0.1-0.2%) and involving ethylene glycol dimethacrylate (0.05-0.2%) as the crosslinking agent;
(iii) Heating the reactor to 65?C and adding 5% pre-emulsion to generate seed based on initiation of polymerization reaction by including tertiary butyl hydro peroxide/sodium formaldehyde sulfoxylate;
(iii) Adding redox couple as a parallel stream to reactor charge together with rest of the pre-emulsion addition for a period of 1 to 4 hr preferably 3.5 hrs;
(iv) Digesting the reaction for about 45 mins, cooling and adding defoamer, biocide and neutralizer affording cationic amine modified polymer latex A.

9. The method of preparing elastomeric pigmented architectural coating formulation as claimed in claims 6-8 wherein said step of mixing in mill base comprises the steps of
(i) Providing anionic emulsion to the mill base post addition of ultra E and defoamer to provide for an intermediate;
(ii) Adding 4% of ammonia to raise the pH of the intermediate to 9.5 followed by adding cationic amine modified latex in the concentration range of 1-5%;
(iii) Mixing for 15 mins affording said paint formulation with ~30% of PVC and amine containing monomer contentbetween 0.2 to 0.32%in the final paint formulation.

Dated this the 23rd day of March, 2022 Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199

, Description:Field of the Invention:
The present invention relates to emulsion formulations suitable for exterior architectural coating with crack bridging ability and resistance to early washout by precipitation. More specifically the invention provides for methanol free fast drying formulation comprising water insoluble anionic and amine modified polymer latexes. The coating is particularly suitable for exterior usage on concrete and masonry surfaces however can also be used in both high PVC and low PVC systems. The system provides the coating with crack bridging ability not known in the systems using amine modified polymers.

Background of the Invention

Concrete masonry unit (CMU) walls are often constructed with an elastomeric coating because they are so porous and usually lack a drainage system. Initial success of an elastomeric coating project is judged on aesthetics/ appearance and waterproofing effectiveness. Similarly, the coating’s durability would be judged by its ability to continue to serve these functions for many years—that is, whether its actual performance (i.e. service life) meets or exceeds the expected useful life (i.e. design life).
Durability of exterior coatings is usually considered as a function of weathering, but an elastomeric wall coating (EWC) may fail long before environmental exposure can cause deterioration. The service life can be cut short by cracks in the substrate telegraphing through the coating. Clearly, it would be a functional failure of an elastomeric coating if water penetrated through cracks—sealing is a fundamental property of these materials.
Elastomeric coatings, as the name implies, these products are selected for their ability to stretch, especially over a new cracks that form or existing ones that widen in the substrate. If the crack propagates through the coating, the system can fail during its first year of service. Crack-bridging ability is the primary distinction between conventional paint and high-performance elastomeric wall coatings (EWCs). Generally, EWCs are more elastic than paint and applied thicker; together, these characteristics allow an EWC to absorb the crack-opening energy within the coating body, preventing the crack from propagating through to the surface. Clear water-repellents are also related to paints and coatings, but generally have no crack-bridging ability.

On the above directions references are drawn to the following based of the publicly available state of the art.

WO 2018085238 A1 relates to a coating composition comprising: a coating base; and 0.1 - 10 wt% of an additive compound, based on the total solids wt. of the coating; where the additive compound is at least one of an alkali metal salt of poly(meth)acrylic acid or copolymer thereof, ammonium compound or amine salt of poly(meth)acrylic acid or copolymer thereof, silicone polyether, alkali metal salt of silicone polyether carboxylate, ammonium compound or amine salt of silicone polyether carboxylate, alkali metal salt of hydrolyzed a-olefin/maleic anhydride copolymer, ammonium compound or amine salt of hydrolyzed a-olefin/maleic anhydride copolymer, alkali metal salt of esterified a-olefin/maleic anhydride copolymer etc. or mixtures thereof; and where the coating base is an architectural paint, architectural stain, or architectural clear coating. Howeverthe advancementis based on the ammonium salt for the carboxylic acid not exactly amine polymers.

US5527853A discloses ashelf-stable fast-cure aqueous coating containing an anionically stabilized latex, a polyfunctional amine and a volatile base in an amount sufficient to deprotonate the conjugate acid of the amine. A shelf-stable fast-cure aqueous coating composition consisting essentially of:
(a) an anionically stabilized emulsion polymer having a Tg greater than about 0° C.;
(b) a water soluble polyfunctional amine polymer having from about 20% to about 100% of the monomer units by weight containing an amine group and having no acid groups other than trace amounts; and
(c) an amount of volatile base sufficient to raise the pH of the composition to a point where essentially all of the polyfunctional amine is in a non-ionic state.

US005922398Ateaches for aqueous coating compositions containing a latex having pendant amine-functional groups, wherein such latex has a Tg greater than about 0 ° C. and is capable of film formation at application temperatures, and an amount of base sufficient to raise the pH of the composition to a point where essentially all of the amine functional groups are in a non-ionic state. Methods for producing fast drying coatings on suitable substrates by application of such coatings, where such coatings develop early water-resistance.

US5824734A relates to an improved fast dry and extremely durable waterborne, coating composition particularly adapted for use as a traffic paint. The basic waterborne coating for traffic paint is comprised of an aqueous emulsion containing an acrylic film forming polymer, a stabilizing system for the emulsion which is pH sensitive, and mineral pigment. Incorporation of a hydrophobic acrylate containing polymer which incorporates from about 0.1 to 5% by weight of a secondary or tertiary amino acrylate and a cross-linkable hydrophobic acrylate monomer less than 5 weight percent as components of the hydrophobic polymer induces the improvement of properties of the coating. But there is no direction for crack bridging ability of the coating.
EP2333022B1 reveals fast dry binder compositions for traffic markings that comprise emulsion polymer binders having a anionically stabilized emulsion polymer having weight average particle size of 165 nm or less, one or more water soluble polyamine, one or more volatile base and one or more filler, extender and/or pigment in a composition %PVC of from 63 to 80.
AU200222985B2 teaches for a storage stable, fast drying aqueous coating composition, said composition comprising: an anionically stabilized binder polymer; a vinylamine polymer having from 20% to 100% by weight of amine functional units, based on total weight of said vinylamine polymer; and an amount of volatile base sufficient to raise the pH of said composition to a point where essentially all of the amine groups of said vinylamine polymer are in a non-ionic state.
WO2017054156A1 provides a shelf-stable aqueous binder composition, comprising: (a) an aqueous dispersion of an anionically stabilized polymer, (b) a water soluble polyfunctional amine polymer, and (c) a suspension or dispersion of a phyllosilicate in a volatile base; wherein the concentration of the phyllosilicate is from 1% to 18% by weight, based on the total weight of the suspension or dispersion, and wherein the volatile base is used in an amount such that the composition has a pH wherein substantially all the polyfunctional amine polymer is in a non-ionic state.

WO2017132089A1 Disclosed aqueous coating compositions containing an anionically stabilized polymer, one or more polyfunctional amines acting as crosslinking agents, and a volatile base. By incorporating one or more polyfunctional amines, such as those comprising recurring units derived from the reaction of one tri-glycidyl moiety and a single di-, or tri-functional amino monomer, or a combination of mono/bi, mono/tri, mono/tetra, bi/bi, bi/tri, bi/tetra, tri/tri, tri/tetra, and tetra/tetra functional amino monomers with a bi- or tri-glycidyl moiety, water wash-off resistance of the coating compositions which comprise paint formulations, can be increased.

WO2020068890A1 relates toCoating and ink formulations that are comprised of an anionically colloidally stabilized copolymer dispersion, a polyamine additive that can react with anionic groups, and a volatile base that can help shift the pH of the copolymer dispersion early in the drying process of films or coatings from the copolymer dispersion.
wherein 0.1 to 10 wt.% of a water dilutable polyamine additive comprising repeating units from the polymerization product of unsaturated monomers, whereinabout 30-90 wt.% of repeating units are from a free radically polymerizable tertiary amine monomer

US10584207B2reveals a latex product composition that includes an anionically-stabilized latex and one or more water solublepolymers or polymeric adducts that have a backbone with a plurality of amine functional groups and hydroxyl functional groups. The polymers or polymeric adducts may be an addition product formed from at least one multifunctional amine compound reacted with one or more polyfunctional epoxy compounds, one or more monofunctional epoxy compounds, or a combination thereof.

US3806485Ateaches fora stable liquid dispersion of a water soluble anionic vinyl addition polymer and a water soluble cationic polymer and novel gel-like structures prepared from these dispersions. The weight ratio of anionic polymer to cationic polymer being within the range of 1:10 to 10:1 and the total amount of anionic and cationic polymer present within said dispersion being within the range of from 0.001% to 75% by weight, both of said polymers being present in the aqueous phase.
EP0409459BDiscloses an aqueous coating composition including an anionically stabilized emulsion polymer having Tg no lower than 0° C, a polyamine functional polymer, and a volatile base in an amount such that the composition has a pH where substantially all of the polyamine functional polymer is in a non-ionic state, and wherein more than 50% by weight of the polyamine functional polymer will be soluble at pH values of 5 to 7 on evaporation of the volatile base. In the non-ionic state (i.e., deprotonated), polyamine interaction with the anionically stabilized emulsion and any other anionic ingredients which may be present in the composition is eliminated. In the absence of the volatile base, the protonated amine moieties interact with the anionic ingredients to destabilize the coating composition.

EP0794018describes an aqueous coating composition having a dispersion of acrylic polymers with acid and amine- functional groups wherein the amine functional groups are in a non-ionic state due to the pH level of such dispersion. The amine and acid functional polymer is prepared in a single polymerization step and the level of amine and acid monomers in the polymer are low; the amine monomer content in the examples is not higher than 7 wt% and the amount of acid monomers in the examples is not higher than 2 wt%.

CN109749001Arelates to anionic acrylic lotions of a cationic monomer and preparation method thereof, on the basis of the lotion dry weight, it is made by the monomer for including following components: acrylic ester monomer 80-99wt%, function monomer acid 0.1-10wt%, cationic monomer 0.1-10wt%, emulsifier 0.1-5wt%.Using the emulsion polymerization of substrate , first it polymerize the pre-emulsion of the acid containing function monomer, then it is neutralized with neutralizer, then polymerize the pre-emulsion of cationic monomer again, this preparation method can carry out in the production equipment of normal anionic acrylic lotion without additional equipment.

EP0290777A2relates to anionic acrylic latices and more specifically a method of preparing anionic acrylic latex compositions containing amino groups. In an improved process for preparing an anionic acrylic latex composition by copolymerizing ethylenically unsaturated monomers which contain an acid group and an amino group under conditions of free-radical initiated addition polymerization in an aqueous medium in the presence of an anionic emulsifier, wherein the acid group containing monomer is an acrylic acid or methacrylic acid. And wherein the amino group containing monomer is a water-soluble or a water-insoluble amino group containing monomer selected from the group consisting of tertiary-butylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate.

WO2016118221A1discloses polyfunctional amine structures exhibiting at least one hydrophobic moiety selected from the group consisting of; hydrophobic epoxides, hydrophobic glycidyl ethers and hydrophobic (meth)acrylates which provide crosslinking capabilities for latex polymer compositions. These crosslinkers not only exhibit latent crosslinking properties but also improved hydrophobicity when compared with existing latex formulations. Latent crosslinking provides advantages associated with fast interactions between the anionic latex charge and the cationic charge associated with these hydrophobically modified polyfunctional amine crosslinkers. Once the latex is coated onto a substrate, the volatile base evaporates and the groups react to form a crosslinked coating with both improved hydrophobic and wash-off properties.
Water based acrylic/styrene acrylic emulsion polymer based pigmented paints cure by the mechanism of coalescence of the polymer particles post evaporation of the solvent. The first step of the evaporation of the solvent, water in this case becomes a function of the environmental conditions, like temperature, humidity, wind speed and Tg of the polymer.

Alternate mechanism of drying of the paint film is the flocculation mechanism triggered by the pH change in the wet film. The paint consists of a weak cationic polyelectrolyte which is in neutral state at high pH and becomes positively charged in the low pH range. The amine functionalised polymer is added in the paint formulation containing an anionic polymer. The loss of neutraliser upon the film application, initiates the flocculation by the ionomer formation of the negatively charges latex particles and the newly formed positively charged latexes by evaporation of the neutralizer. The flocculation mechanism doesn’t drive the water fast out of the film, but sets fast and is able to withstand the showers even in the wet stage. The fast setting tendency of the film even in wet state, gives the superior flow and levelling.

Traversal of the prior art above clearly indicates that early shower resistance property is widely harnessed in road marking paints where it is achieved by interaction of pH responsive amine functionalized water soluble polymer with the anionic emulsion polymers. The formulations use methanol for fast evaporation of the solvent which contributes to VOC of the paints. Often additional drying aids/water absorbents like porous hygroscopic silica and inorganic acids or acidic coagulants are used in during application as multiple coats.

The same concept has been extended to the architectural coatings wherein amine derivatised polymers are either water soluble polymer like polyvinylamines, lupasol- both linear and dendritic forms or amine functional latexes are used with the acid functionalised latexes. In addition the polyamine based fast drying aids are available in the market to be used as on the spot mix aids during application in rains for early shower resistance property. e.g. Quick trigger by BASF.But a shelf stable single component paint combining the quick setting property along with the crack bridging ability for the exterior application is not yet known in the prior art. Thus there exists a scope for exploration of emulsion latexes including pH responsive amine functionalized polymer with the anionic emulsion polymers as a decorative coating suitable for concrete and masonry surfaces.

Objectives of the invention

It is thus the primary objective of the present invention is to providefor emulsion coating formulationsor suspensions having crack bridging ability not known in the elastomeric systems by involving amine modified polymers.

Another objective of the present invention is to provide said emulsion formulation or suspensions which would render the pigmented coating crack bridging ability with early shower resistance and faster drying in high humidity.

Another objective of the present invention is to provide said emulsion formulation or suspensions which would exhibit dirt pick up resistance.

Another objective of the present invention is to provide said emulsion formulation which would not require water absorbents or acidic coagulants during application as multiple coats.

Yet another objective of the present invention is to provide said emulsion formulation which would enable to provide a shelf stable, low VOC, single pack architectural exterior coating.

Another objective of the present invention is to provide said formulation of suspensions which would comprise ofwater insoluble anionic and amine functionalized cationic polymer in a select ratio that would enable crack bridging ability as elastomeric systems.

Another objective of the present invention is to provide said formulation of suspensions which would be free of methanol to reduce the toxic VOC content of the formulation but still would be fast drying.

Another objective of the present invention is to provide said suspension system which would be suitable for exterior usage on concrete and masonry surfaces and also including both high PVC and low PVC systems showing crack bridging ability as well as early shower resistance by precipitation.

Summary of the Invention

Primary embodiment of the present invention is directed to provide an elastomeric pigmented architectural coating formulation facilitating early washout resistance, crack bridging ability and faster drying in humid conditions comprising
water insoluble anionic latex polymer having Tg less than 15 deg C;
and amine modified polymer latexes;
wherein the ratio of the anionic and cationic polymer latex in the paint formulation is from 15:1 to 8:1 particularly suitable for exterior usage on concrete and masonry surfaces however can also be used in both high PVC and low PVC systems.

Another embodiment of the present invention is directed to provide said Elastomeric pigmented architectural coating formulation that is free of methanol to reduce the toxic VOC content of the formulation and is fast drying, wherein the amines containing monomer content in the final paint is between 0.2-0.32% and backbone of the said anionic latex is crosslinked with selective dose of crosslinker (0.1-to 0.5 %) to impart dirt pick up resistance and both improved hydrophobic and wash-off properties.

Yet another embodiment of the present invention is directed to provide said elastomeric pigmented architectural coating formulation containing said water insoluble anionic latex polymer and amine modified polymer latexes wherein
said water insoluble anionic latex includes acrylic or styrene acrylic latexes obtained of anionic surfactants; and
said amine functionalized latexes includes 3- dimethylaminopropyl methacrylamide modified latexes.

Yet another aspect of the present invention is directed to provide said elastomeric pigmented architectural coating formulation having early shower resistance similar or superior than commercial paints under both lab condition and humidity chamber condition, lesser touch dry time and significantly higher crack bridging ability 0.1-0.5mm preferably more than 0.24 mm) @ 150 microns curing for 14 days.

Further aspect of the present invention is directed to provide said elastomeric pigmented architectural coating formulation wherein
said water insoluble anionic latex includes acrylic or styrene acrylic latexes, obtained of emulsion polymerization by involving anionic surfactants; and
said amine functionalized latexes including 3-dimethylaminopropyl methacrylamide modified latexes are obtained of addition polymerization of ethylenically unsaturated monomers containing amine-functionality; polymerization of monomers which readily generate amines by hydrolysis; reactions of aziridines with carboxyl-containing polymers; reactions of polymers containing an enolic carbonyl group, e.g., acetoacetoxyethyl methacrylate ("AAEM"), and diamines; reactions of amines with epoxy-containing polymers; and reactions of amine with polymers of vinyl benzyl chloride particularly emulsion polymerization.

Another aspect of the present invention is directed to provide amethod of preparing elastomeric pigmented architectural coating formulation comprising the steps of
Providing water insoluble anionic latex polymer having Tg less than 15 deg C;
Providing amine modified polymer latexes in the ratio of 15:1 to 8:1; and
Mixing in mill base by involving balance ingredients of a paint formulation including 4% of ammonia to obtain said elastomeric paint formulations thereof.

Further aspect of the present invention is directed to provide said method of preparing elastomeric pigmented architectural coating formulation wherein providing water insoluble anionic latex polymer having Tg less than 15 deg C comprises the steps of
(i) Charging the reactor with surfactant and water to make a surfactant solution including Dowfax 2A1 in water;
(ii) Providing Pre-emulsion by dissolving Dowfax 2A1 (45% solution) (0.6-1.0%) and Atpol 5731non-ionic surfactant (0.1-0.5%), in water and adding methyl methacrylate (20-25%), butyl acrylate (23-28%), hydroxyl ethyl methacrylate (1-4%), optifilm enhancer 300 (0.8-2%), di-acetone acrylamide (0.1-0.5%), vinyl trimethoxysilane (0.2-0.4%), and methacrylic acid (0.5-1%);

(iii) Heating the reactor to 80 ?C followed by adding 5% of the pre-emulsion to initiate the seeding including adding potassium per sulfate and sodium bi carbonate solutions followed by adding the rest of the pre-emulsion after time gap of 15 mins which addition is done for a time period of 2 hr to 8 hrpreferably 4 hrs at 80 ?C;
(iv) post complete addition of pre-emulsion, digestion catalyst is added and digestion continued for 45 minutes followed by cooling the reaction mass and adding additives at 45 ?C favouring water insoluble anionic latex polymer Latex B with Tg <15 OC and a minimum film forming temperature of >4 OC.

Still further aspect of the present invention is directed to provide saidmethod of preparing elastomeric pigmented architectural coating formulation wherein providing amine functionalized latexes comprises the steps of
(i) Charging the reactor with water, 2-amino-2-methyl-1-propanol (0.02-0.1%), Dowfax A 45 (0.1-0.5%) and non-ionic surfactant Tergitol 15-S-40 (0.5-2%).

(ii) providing pre-emulsion by emulsifying monomers including methyl methacrylate (14-18%), butyl acrylate (14-18%) and 2-(dimethyl amino) propyl methacrylamide (6-10%) in water in presence of tergitol 15-S-40 surfactant (1.5-3.5%) and 2-amino-2-methyl-1-propanol (0.1-0.2%) and involving ethylene glycol dimethacrylate (0.05-0.2%) as the crosslinking agent;
(iii) Heating the reactor to 65?C and adding 5% pre-emulsion to generate seed based on initiation of polymerization reaction by including tertiary butyl hydro peroxide/sodium formaldehyde sulfoxylate;
(iii) Adding redox couple as a parallel stream to reactor charge together with rest of the pre-emulsion addition for a period of 1 to 4 hr preferably 3.5 hrs;
(iv) Digesting the reaction for about 45 mins, cooling and adding defoamer, biocide and neutralizer affording cationic amine modified polymer latex A.

Yet another aspect of the present invention is directed to provide said method of preparing elastomeric pigmented architectural coating formulation wherein said step of mixing in mill base comprises the steps of
(i) Providing anionic emulsion to the mill base post addition of ultra E and defoamer to provide for an intermediate;
(ii) Adding 4% of ammonia to raise the pH of the intermediate to 9.5 followed by adding amine modified latex in the concentration range of 1-5%;
(iii) Mixing for 15 mins affording said paint formulation with ~30% of PVC and amine containing monomer contentbetween 0.2 to 0.32%in the final paint formulation.

Detail Description of the Invention
As mentioned hereinbefore, present invention provides for methanol free fast drying elastomeric coating formulation comprising water insoluble anionic polymer and cationic amine modified polymer latexes. The system combines both early shower resistance and crack bridging ability to the paint formulation suitable for exterior architectural coating applications. The coating is particularly suitable for exterior usage on concrete and masonry surfaces however can also be used in both high PVC and low PVC systems.

The flocculation mechanism in combination with the smartly designed anionic latex in accordance to the present invention also provides the required elongation with the tensile strength.The Tg of said anionic latex in accordance to the present invention is kept less than 15 C preferably less than 12 C to manifest the required elongation. As the latex is used for the exterior application, the dirt pick up resistance is also renderedby the cross-linkers in the anionic backbone with the selective dosage of 0-0.4%. The ratio of the anionic and cationic polymer in the paint formulation is from 15:1 till 8:1. The content of the amine containing monomer in the final paint between 0.2 to 0.32%. Increasing the concentration of amine containing latexes beyond the select concentration destabilises the paint and leads to gelling in hot box study.

In the primary embodiment of the present invention the emulsion formulation is comprised of amine modified cationic emulsion latexes and water insoluble anionic latexes wherein the ratio of the anionic and cationic polymer in the paint formulation is from 15:1 to 8:1. The simultaneous existence of the crack bridging ability and early shower resistance of the formulation is a function of Tg of the anionic polymer and is found to be less than 15 deg C because more than 15deg C Tg, nolongershows elongation and the crack bridging ability cannot be achieved. Higher Tg latexes also show poor stability in the final paint formulation.

In another embodiment of the present advancementthe select content of the amines containing monomer in the final paint/ emulsion is found in the range of 0.2% to 0.32%to achieve the benefit of its crack bridging ability and resistance to early washout by precipitation together.Below thelevel of 3.4% of the amine latexes, the early shower resistance is not achieved and very interestingly when the concentration of the same (amine latex) is higher than 5% the paint doesn’t show the crack bridging ability and demonstrates poor heat ageing stabilityand leads to gelling in hot box study. Surprisingly the synergistic special coaction of the amine modified cationic emulsion latexes and anionic latexes in the very selective window of amine functionality concentration enables incorporation of both crack bridging ability and early shower resistance together in the formulation.

It is important to note that the amines used for the present invention are insoluble in water. When water soluble amines were tried vis-à-vis water insoluble amines- the former was required in much higher concentrations to achieve the same effect. Said higher concentration of the water soluble amines generated high viscosity resulting in poor stability of the system. Most importantly, the water soluble amines could not impart crack bridging ability in the system. Water soluble amines also showed poor weatherability on exterior exposure.

In another embodiment the amine-functionalized latexes of the advancement may be prepared in accordance with any of a number of methods, including but not limited to: addition polymerization of ethylenically unsaturated monomers containing amine-functionality; polymerization of monomers which readily generate amines by hydrolysis; reactions of aziridines with carboxyl-containing polymers; reactions of polymers containing an enolic carbonyl group, e.g., acetoacetoxyethyl methacrylate ("AAEM"), and diamines; reactions of amines with epoxy-containing polymers; and reactions of amine with polymers of vinyl benzyl chloride. Such polymerization reactions are known in the art. The amine functionalized latexes suitable for the present invention includes 3- dimethylaminopropyl methacrylamide modified latexes.
In another embodiment of the present advancement the anionic polymer includes Acrylic or styrene acrylic latexes prepared using anionic surfactants.

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:

As stated hereinbefore the emulsion formulations suitable for exterior architectural coating with crack bridging ability and resistance to early washout by precipitation in accordance to the present invention compriseswater insoluble anionic polymer and cationic amine modified polymer latexes. The detailed method of their preparation are discussed below:

Example-1
Synthesis of amine functionalized latexes:
Amine functionalized latex (Latex A)isprepared by conventional emulsion polymerization wherein the reactor is charged with water, 2-amino-2-methyl-1-propanol, Dowfax A 45 and non-ionic surfactant Tergitol 15-S-40 in specified quantities as mentioned in Table-1. The Pre-emulsion is made by emulsifying monomers- methyl methacrylate, butyl acrylate and 2-(dimethyl amino) propyl methacrylamidein water in presence of tergitol 15-S-40 surfactant and 2-amino-2-methyl-1-propanol. Ethylene glycol dimethacrylate is used as the crosslinking agent.

The reactor is heated to 65?C. 5% pre-emulsion is used to generate seed and tertiary butyl hydro peroxide/sodium formaldehyde sulfoxylate is used for initiating the reaction. A parallel stream of redox couple is added to the reactor charge to continue the reaction. Pre-emulsion addition is continued for 3 -5 hrs. After the completion of pre-emulsion addition, the polymer is digested using the redox couple for about 45 minutes. The reactor is cooled after digestion and later on added with defoamer, biocide and neutraliser.

Table 1: Reagents and solvent used for amine functionalized latex

Raw materials % W Range% of the ingredients
D M Water 18.00 15-20%
Dowfax A 45 0.20 0.1-0.5%
Tergitol ™ 15-S-40 1.0 0.5-2%
2-Amino-2-Methyl-1-Propanol 0.05 0.02-0.1%
D M Water 2.00 0.5-5%
Initiator For Seed
Tertiary Butyl Hyderoperoxide 0.15 0.04-0.4%
D M Water 0.90 0.2-1.5%
Sodium Formaldehyde Sulphoxlate 0.15 0.04-0.4%
D M Water 0.90 0.2-1.5%
PREEMULSION

D M Water 16.50 15-18%
Tergitol 15-S-40 2.50 1.5-3.5%
Butyl Acyrlate 16 14-18%
Methyl Methacrylate 16 14-18%
2-(Dimethyl Amino) Propyl Methacrylamide 8 6-10%
2-Amino-2-Methyl-1-Propanol 0.13 0.1-0.2%
Ethylene Glycol Dimethacyrlate 0.1 0.05-0.2%
D M water 2.0 1-3%
Flushing D M Water 2.00 1-3%
Parallel Shot Addition
Tertiary Butyl Hyderoperoxide 1.05 0.8-1.5%
D M Water 5.0 3-8%
Sodium Formaldehyde Sulphoxlate 1.05 0.8-1.5%
D M Water 5.0 3-8%
Additives
Biocide 0.16 0.1-2%
Defoamer 0.02 0.01-0.03%
D M Water 0.08 0.06-1%
Liquor Ammonia 0.50 0.4-0.6%
D M Water 0.56 0.3-0.7%
Total 100

Synthesis of anionic polymeric latex: Anionic latexes (Latex B) are synthesized by the conventional emulsion polymerization. In the reactor, surfactant is added with water to make a surfactant solution. Pre-emulsion is made by dissolving Dowfax 2A1 (45% solution) and Atpol 5731, non-ionic surfactant in water and adding methyl methacrylate, butyl acrylate, hydroxyl ethyl methacrylate, optifilm enhancer 300, di-acetone acrylamide, Dynasylan® vinyl trimethoxysilane, and methacrylic acid as per the composition given in the table 2. Reactor is charged with water and Dowfax 2A1 and is heated to 80C. The pre-emulsion is stirred well and 5% of the pre-emulsion is added to the reactor to initiate the seeding. Potassium per sulfate and sodium bi carbonate solutions were added to the reactor to initiate seeding. After 15 mins, the rest of the pre-emulsion is added for a period of 4 hrs at 80C. After pre-emulsion is completely added, the digestion catalyst is added. Digestion continued for about 45 minutes followed by cooling the reaction mass. AT 45, additives are added. Tg as measured by DSC for Latex B is 12 OC with a minimum film forming temperature of 4.6 OC.

Table 2: Reagents and solvent used for water insoluble anionic latex B

Reactor charge PBW Range % of the ingredients
D M Water 18.00 16-20%
Dowfax2A1(45% solution) 1.00 0.75-1.25%
Sodium bicarbonate 0.14 0.1-0.2%
D M Water 2.40 2-3%
Potassium per sulfate 0.14 0.1-0.2%
D M Water 2.90 2-4%
Seed (5 %)
Pre-emulsion
D M Water 15.50 13-17%
Dowfax2A1(45% solution) 0.80 0.6-1.0%
ATPOL 5731 0.30 0.1-0.5%
Methyl methacrylate 21.60 20-25%
Butyl acrylate 24.00 23-28%
Methacrylic acid 0.60 0.5-1%
Hydroxy ethyl methacrylate 2.00 1-4%
Potassium per sulfate 0.06 0.03-0.08%
D M Water 1.00 1-2%
Vinyl tri methoxy silane 0.25 0.2-0.4%
Optifilmenhancer 300 1.10 0.8-2%
Diacetone acrylamide 0.20 0.1-0.5%
Demineralised water 0.30 0.2-0.4%
FLUSHING Demineralised water 1.00 0.5-1.5%
DIGESTION
Sodium formladehyde sulfoxylate 0.02 0.01-0.03%
D M Water 1.00 0.5-1.5%
Tertiary butyl hydroperxide 0.02 0.01-0.03%
D M Water 1.00 0.5-1.5%
ADDITIVES
Biocide 0.20 0.1-0.3%
D M Water 0.10 0.05-0.15%
Adipic acid dihydrazide 0.10 0.05-0.25%
D M Water 3.00 2-5%
Liq NH3 0.60 0.3-0.9%
D M Water 0.30 0.1-0.5%
Defoamer 0.02 0.01-0.04%
D M Water 0.35 0.2-0.5%
Total 100.00

Anionic Latex C –Latex C is synthesized in similar fashion as Latex B and uses two pre-emulsion A and B. Pre-emulsion B is added immediately after pre-emulsion A is finishes. Tg for Latex C is 19.2 OC with a minimum film forming temperature of 8.8 OC.

Table 3: Reagents and solvent used for water insoluble anionic latex C

Reactor Charge Rage of ingredients
D M Water 14.00 12-20%
Sodium Lauryl sulfate 0.10 0.05-0.3%
SODIUM BICARBONATE COMM/LR) 0.15 0.1-0.2%
D M Water 1.70 1-2.5%
POTASSIUM PERSULPHATE 0.14 0.1-0.2%
D M Water 1.70 1-2%

Monomer Pre-emulsion 1
D M Water 10.00 8-12%
Sodium Lauryl Sulfate 0.20 0.1-0.3%
D M Water 0.50 0.3-0.7%
Styrene Monomer 9.00 8-10%
Butyl Acrl-I 11.00 10-12%
Acrylic Acid 0.50 0.3-0.8%
D M Water 0.10 0.05-0.2%
Ethylene Glycol Dimethacrylate (Egdma). 0.10 0.05-0.2%
D M Water 0.10 0.05-0.2%
Potassium Persulphate 0.02 0.01-0.1%
D M Water 0.40 0.2-0.6%
Add VTMO To PE After PE Addition 25% (45 Mins ).
Flush With D M Water.
VTMO 0.33 0.2-0.5%
D M Water 0.20 0.1-0.3%
WATER For Flushing
D M Water 0.70 0.5-0.9%
Monomer Pre-Emulsion 2
D M Water 12.00 10-14%
Sodium Lauryl Sulfate 0.30 0.2-0.5%
D M Water 0.50 0.3-0.7%
Butyl Methacrylate 25.00 20-30%
Butyl Acrl-I 2.00 1-5%
Acrylic Acid 0.30 0.1-1%
D M Water 0.10 0.05-0.2%
Potassium Persulphate 0.02 0.01-0.03%
D M Water 0.20 0.1-0.3%
Add DAAM To PE After Monomer Pre-Emulsion 2 Addition 80% (120 Minutes)
Diacetone Acrylamide 0.40 0.2-0.6%
D M Water 0.40 0.2-0.6%
WATER For Flushing
D M Water 0.70 0.5-0.9%
Digestion
Tertiary Butyl Hyderoperoxide 0.040 0.02-0.06%
Sodium Lauryl Sulfate 0.100 0.05-0.2%
D M Water 1.900 0.7-2.1%
Sodium Formaldehyd Sulphoxlate 0.040 0.02-0.06%
D M Water 1.200 1-2%
Additives:
Biocide 0.200 0.1-0.4%
D M Water 0.100 0.05-0.5%
Adipic Dihydrazide 0.200 0.1-0.3%
Sodium Lauryl Sulfate 0.040 0.02-0.06%
D M Water 1.000 0.5-1.5%
Defoamer 0.020 0.01-0.05%
D M Water 0.100 0.05-0.2%
Liquor Ammonia 0.700 0.5%-1%
D M Water 0.200 0.1-0.4%
WATER For Flushing
D M Water 1.300 1-2%
Total 100.00

Experimental Paint- A typical paint formulation is obtained by adding anionic emulsion to the mill base after addition of ultra E and defoamer. 4% of ammonia is added to raise the pH of the intermediate to 9.5 and then the amine containing latex is added. The PVC (pigment volume concentration) of the system is about 30%. The experimental samples were made at three different levels of amine containing latexes of 1%, 3.4% and 5%. The anionic latex content is adjusted accordingly.

Compound PBW
Mill base 40.85
Defoamer 0.10
Ultra E 18
Anionic Emulsion (Latex B/C) 36.05/33.65/31.65
NH3 4
Amine modified latex(Latex A) 1/3.4/5
Total 100

At 3% of the amine functionalized latex, the paint is stableand it was observed that above 5% of the amine functionalized latex, the paint is not stable and undergoes gelling within a week.

Control sample- The same formulation as above without the amine modified latexes and substituting the same with anionic polymer to maintain equivalent polymer content.Same formulation protocol as above was followed to obtain thecontrol sample.
Compound PBW
Mill base 40.85
Defoamer 0.10
Ultra E 18
Anionic Emulsion(Latex B/C) 37.05
NH3 4
Total 100

Example-2
Early Washout resistance:
3 paint compositions paint 2, paint 3 and paint 4 having different concentration ofamine modified Latex A along with anionic Latex B were applied on glass plate in comparison with paint 1 having no Latex A (only latex B) in the paint formulation with film thickness of approximately 150 microns and evaluated for early washout resistance. Similarly, paints 6,7, and 8 comprising Latex C as anionic latex and Latex A as the amine modified latex in the specified ratios were prepared and applied on glass plate wherein control Paint 5 is having no Latex A (only Latex C). The glass panels were then placed in humidity chamber and in lab atmosphere. After specific drying time glass panels were taken out and placed under stream of water shower of area 15 square centimeter with water flow rate 3 gm/min to evaluate early shower resistance of the formulated paints.

Early shower resistance (for Latex B based)
Paint Experimental Paint Performance in lab conditions
Commercial Paint Paint 1 (control) Equivalent with std*
Commercial Paint Paint 2 (Latex A) (1%) Equivalent with std
Commercial Paint Paint 3 (Latex A) (3.4%) Slightly better than std
Commercial Paint Paint 4 (Latex A) (5%) better than std
*The commercial sample is mentioned as standard

Early shower resistance (for Latex C based)
Paint Experimental Paint Performance in lab conditions
Commercial Paint Paint 5 (control) Inferior than std
Commercial Paint Paint 6(Latex A) (1%) Equivalent with std
Commercial Paint Paint 7(Latex A) (3.4%) better than std
Commercial Paint Paint 8 (Latex A) (5%) better than std

Paint Early washout resistance (for Latex B based) after humidity chamber after 10 minutes of drying (60%RH @T:22 O C)
Paint 1 (control) Fail, film detaches
Paint 2(Latex A) (1%) Fail, film detaches
Paint 3 (Latex A) (3.4%) Pass
Paint 4 (Latex A) (5%) Pass
Commercial Sample Fail, film detaches

Paint Early washout resistance (Latex B based) after humidity chamber after 20 minutes of drying (85%RH @T:22 O C)
Paint 1 (control) Fail, film detaches
Paint 2(Latex A) (1%) Fail, film detaches
Paint 3 (Latex A) (3.4%) Pass
Paint 4 (Latex A) (5%) Pass
Commercial Sample Fail, film detaches

Paint formulations of both anionic latex B and C along with amine modified polymer 3.4 and 5% respectively show either similar or better early shower resistance than the control or commercial paint formulations. However incorporation of 1% amine containing latex in the paint formulation does not exhibit desired early shower resistance property.

Example-3
Touch dry time:
3 paint compositions paint 2, paint 3 and paint 4 having different concentration ofamine modified Latex A along with anionic Latex B were applied on glass plate in comparison with paint 1 having no Latex A (only latex B) in the paint formulation with film thickness of approximately 150 microns and evaluated for touch dry time.
Touch dry time (for Latex B) in lab condition
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Commercial Paint 20 Paint 1 (control) 20
Commercial Paint 20 Paint 2(Latex A) (1%) 20
Commercial Paint 20 Paint 3(Latex A) (3.4%) 17
Commercial Paint 20 Paint 4(Latex A) (5%) 14

Touch dry time (for Latex B based) in humidity chamber (60%RH,T-22? C)
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Paint 1 (control) 11 Paint 2(Latex A) (1%) 11
Paint 1 (control) 11 Paint 3(Latex A) (3.4%) 8
Paint 1 (control) 11 Paint 4(Latex A) (5%) 7
Commercial sample 27

Touch dry time (for Latex B based) in humidity chamber (85%RH, T-22? C)
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Paint 1 (control) 17 Paint 2 (Latex A) (1%) 15
Paint 1 (control) 17 Paint 3(Latex A) (3.4%) 12
Paint 1 (control) 17 Paint 4(Latex A) (5%) 10
Commercial latex 35

Touch dry time (for Latex C based) in lab condition
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Commercial Paint 20 Paint 5 (control) 19
Commercial Paint 20 Paint 6 (Latex A) (1%) 17
Commercial Paint 20 Paint 7(Latex A) (3.4%) 15
Commercial Paint 20 Paint 8 (Latex A) (5%) 13

Touch dry time (for Latex C based) in humidity chamber (60%RH,T-22? C)
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Paint 5 (control) 9 Paint 6(Latex A) (1%) 9
Paint 5 (control) 9 Paint 7(Latex A) (3.4%) 7
Paint 5 (control) 9 Paint 8(Latex A) (5%) 6
Commercial Paint 27

Touch dry time (for Latex C based) in humidity chamber (85%RH,T-22? C)
Paint Touch dry time (min) Experimental Paint Touch dry time (min)
Paint 5 (control) 16 Paint 6(Latex A) (1%) 16
Paint 5 (control) 16 Paint 7(Latex A) (3.4%) 14
Paint 5(control) 16 Paint 8(Latex A) (5%) 13
Commercial Paint 35

The invented formulations showed either similar or better touch dry time with respect to the control sample and much improved performance than the commercial samples under all the drying condition tested.

Example-4
Evaluation of Crack –bridging ability

Coating system:Weight/ Litre= 1.2871 kg/litre

FOR150micron DFT: (3 Coats)

First coat: The product is diluted to 2.5 :1 by Volume (paint: water),applied by brush ensuring the deposition of 186.05 gm/m2 and allowed to dry for 4 to 6 hrs.

Second coat: The product is diluted to 2.5 :1 by Volume (paint: water), applied by brush ensuring the deposition of 186.05 gm/m2 and allowed to dry for 4 to 6 hrs.
Third coat: The product is diluted to 2.5 :1 by Volume (paint: water), applied by brush ensuring the deposition of 186.05 gm/m2and allowed to dry for 4 to 6 hrs.

Overall Deposition: Based on above description, overall deposition for AS14S for horizontal surfaces was 558.15 gm/m2 for total 3 coats.

Sr. No. Property Crack bridging ability @ 150 microns curing for 14 days
1 For Latex C based Paint system
Reading in Duplicate Avg.
a) Paint 1 (control) 0.15 mm 0.135 mm
0.12 mm
b) Paint 2 Latex A (1%) 0.07 mm 0.075 mm
0.08 mm
c) Paint 3 latex A (3.4%) 0.12 mm 0.11 mm
0.1 mm
d) Paint 4 Latex A (5%) 0.16 mm 0.17 mm
0.18 mm
2 For Latex B based Paint system
Reading in Duplicate Avg.
e) Paint 1 (control) 0.07 mm 0.06 mm
0.05 mm
f) Paint 2 Latex A (1%) 0.21 mm 0.205 mm
0.2 mm
g) Paint 3 Latex A (3.4%) 0.25 mm 0.245 mm
0.24 mm
h) Paint 4 Latex A (5%) 0.27 mm 0.275 mm
0.28 mm

Out of anionic latex B and C used for paint formulation along with different concentration of amine modified Latex A, only Latex B showed significant improvement of crack bridging capability.

Thus present invention enables successful incorporation of crack bridging ability and resistance to early washout by precipitation to emulsion formulations suitable to be used for exterior architectural coating. Selective ratio of the select water insolubleanionic polymer and select amine modified polymer including less than 15 deg CTg of the anionic polymer impart selectivelysimultaneous existence of the crack bridging ability and early shower resistance to the formulation.The ratio of the anionic and cationic polymer in the paint formulation is 15:1 to 8:1 wherein the concentration of the aminecontaining monomer is maintained between 0.2% to 0.32%.The present invention thus attains shelf stable, low VOC, fast drying, single pack architectural exterior coating formulation renderingboth crack bridging ability as well as early shower resistance.