Description:FIELD OF INVENTION:
The present invention relates to acrylic emulsion polymer and architectural coating formulations thereof with excellent anti-efflorescence, water resistance as well as solvent resistance particularly mineral turpentine oil (MTO) resistance. Particularly, the present invention relates to the synthesis of styrene-acrylic/acrylic latex for architectural coating including at least one hydrophilic chelating monomer.
BACKGROUND ART:
Styrene-acrylic emulsions are a versatile class of polymers which find applications in architectural coating, protective coating, wood coating, paper coating, adhesive, sealant, etc. One of the main requirements of polymeric coating material is their capability to confer water resistance to substrates. Since the polymer is a major part of coating composition, hydrophobicity of polymer becomes need for the same. Incorporation of hydrophobic moiety is the well-known route to achieve better water resistance. According to the prior art, styrene, VeoVa 10, VeoVa 9, n-butyl methacrylate, etc. are most commonly used monomers to improve water resistance due to their higher hydrocarbon content.
In few regions, solvent (MTO) based wall putty/post plaster putty is used to get better finish of wall in optimum cost. The solvent is evaporating slowly and shows adverse impact on the hydrophobic coating. It is mainly due to high percentage of hydrophobic monomers which are chemically similar with/ mimic of mineral turpentine oil and other solvents. In such scenario, polymeric latex with excellent water & solvent (MTO) resistance is the emerging need for the architectural coatings.
Dashtizadeh et al. in Applied Surface Science, Volume 257, Pages 2118–2125, Journal 2011 reports the synthesis of acrylic latex with improved hardness, solvent resistance and glossiness by using silica nanocomposites. The improvement in solvent resistance observes with increasing silica content. It is because of decreasing the organic raw materials content of latexes.
US005191029A discloses polymer composition based on phosphorus moiety and water-soluble polyvalent metal compounds. The phosphorus groups are incorporated as pendent and/or terminal and water-soluble polyvalent metals are selected from Co+2, Zn+2, Ni+2 and Zr+2. The resulting polymer composition shows improvement in solvent, chemical, and print resistance properties. However, does not relate to about water resistance & stability of polymer in presence of polyvalent metals.
US 9,499,679 B2 discloses the process for synthesis of formaldehyde free acrylic emulsion polymers containing acid functional monomers in the range of 30-100 % & other hydrophilic monomers up to 5% based on total monomer concentration. Resulting polymer composition shows improvement in the solvent resistance. However, does not provide any information about the water resistance of synthesized polymer.
US6465563B1 discloses polymer coating composition for automotive coating which adheres well to poly (phenylene oxide)-based materials along with improved chemical resistance particularly oil and grease. The coating composition is made by using about 30-35% of styrene acrylic polymer, 30-35% of acrylic polymer & 30-40% of acrylic-urethane hybrid polymer.
Recently, Jumrus et al. in Materials Letters. Volume 304, Page 130618, Journal 2021 has reported a transparent and water-resistant superhydrophobic acrylic surface material by using tetrahydrofuran/isopropyl alcohol (THF/IPA) etching assisted SiO2 nanoparticles (NPs).
US20040225051A1 explains about water-in-water multicoloured paint composition based on carboxylate polymer admixed with film-forming, crosslinkable, hydrophobic polyisocyanate. It claims improved solvent & water resistance after drying. This prior coating composition is based on isocyanate chemistry.
WO2017095881A1 explains the polymer composition with use of two acid functional monomers for improved hydrophobic and hydrophilic stains. Teaches about two acid functional monomers out of which one selected from phosphorous based, sulphur based or mixture of them. However, does not relate to the attainment of solvent and water resistance.
WO2021016559A claims coating composition for improved stain resistance using mixture of two polymeric systems. Out of which one synthesized from monomer having acid or amine group. However, it does not explain about coating composition with single polymeric system having acid functionality for both water and solvent resistance.

CA1268294A teaches coatings, optionally containing no emulsifiers, are prepared from copolymers of polymerizable, surface-active alkyl phosphates. A copolymer was prepared by emulsion polymerization of styrene 75, Butyl acrylate (BA) 82, acrylic acid 0.3, and hexapropylene glycol methacrylate phosphate (1:1) 2.7 g. A coating of this emulsion on cold-rolled steel showed only light rusting in the flash rusting test and salt spray corrosion (300 h) 0 and 2.4 mm unscribed and scribed, respectively. This prior patent teaches the inclusion of optional anionic and non-ionic surfactant. Does not teach administration of the coating on cementitious substrate.
Boosting protective properties of latex binders, May 2011; Polymers Paint Colour Journal 201(4560):29-30 teaches Croda's Maxemul range of reactive surfactants or non-migratory surfactants for emulsion polymerization are found to improve water repellency and barrier properties, thus increasing protective properties of latex binders. However, does not relate to the attainment of solvent resistance along with water resistance.
Adhesion enhancement in waterborne acrylic latex binders synthesized with phosphate methacrylate monomers; January 2008; Progress in Organic Coatings 61(1):38-44 teaches latexes synthesized using a delayed addition of the phosphate monomer that showed better performance than latexes prepared following a conventional addition strategy. The latexes synthesized during the investigation were evaluated as binders in a primer formulation. A primer with good adhesive and corrosion resistance properties was achieved using a 5 wt.% of the phosphated monomer.

CA2782404C teaches a crystalline colloidal array of particles is disclosed, which includes reactive surfactant covalently bound to the particle surfaces. During formation of the array, the bound surfactant remains in position on the particles resulting in reduced quantity of defects compared to arrays of particles produced with non-reactive surfactants.

In spite of the above known state of the art there is still a need in the art to provide for emulsion polymer and architectural coating formulations thereof based on styrene-acrylic/acrylic latex which would impart excellent anti-efflorescence, water resistance along with solvent resistance attributes, particularly MTO resistance and would also show good adhesion on dry as well as damped cementitious material.

OBJECTIVES OF THE INVENTION
It is thus the basic objective of the present invention to provide for a stable emulsion polymer and architectural coating formulation thereof that would have excellent anti-efflorescence, water resistance as well as solvent resistance particularly mineral turpentine oil (MTO) resistance.
Another objective of the present invention is to provide for a process of preparation of said stable emulsion polymer of styrene-acrylic/acrylic monomer combinations to enable said coating formulations.
Still another objective of the present invention is to provide for said coating formulations with excellent adhesion on dry and damp cementitious substrates.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided an acrylic emulsion polymer and architectural coating formulation thereof comprising (a) reactive/non-migratory surfactant and chelating monomer in the levels of at least 3.4 wt.% of the emulsion, OR, (a) (i) reactive/non-migratory surfactant and chelating monomer in the levels of at least 2.55 wt.% of the emulsion & (a) (ii) silane functional co-monomer in the levels of at least 0.4 wt.% of the emulsion;
(b) hydrophobic monomer/s in amounts of 30-50 wt.% of the emulsion;
(c) non-reactive surfactant including non-ionic surfactant in amounts of 1-2.5 wt.% of the emulsion;
adapted for stable emulsion polymer with anti-efflorescence, water and solvent resistance on dry and damped cementitious substrates.
According to a preferred aspect of the present invention there is provided said acrylic emulsion polymer formulation wherein said reactive/non-migratory surfactant of component (a) is present in the levels of 1.0 to 4.0 wt.% of the emulsion.
Preferably said acrylic emulsion polymer formulation is provided wherein said chelating monomer of component (a) is present in the levels of 1.0 to 2.5 wt.% of the emulsion.
According to a preferred aspect of the present invention there is provided said acrylic emulsion polymer formulation wherein said (a) (i) reactive/non-migratory surfactant and chelating monomer in the final emulsion are incorporated in the levels of 1.0 to 4.0 and 1.0 to 2.5 wt.% of the emulsion respectively & (a) (ii) silane functional co-monomer is present in the levels of in the levels of 0.40-0.60 wt.% of the emulsion.
Preferably in said acrylic emulsion polymer formulation said reactive and non-reactive surfactants include phosphorous/sulphur based non-migratory and/ or migratory surfactant/s;
said chelating monomer/s are selected from Methacrylic acid, acrylic acid, Itaconic acid, Maleic acid, phosphate functional monomer including Vinyl phosphonic acid, phosphate;
said hydrophobic monomers includes butyl acrylate (BA), 2-Ethylhexyl acrylate, Styrene, n-butyl methacrylate, cyclohexyl methacrylate, tertiary butyl methacrylate;
said silane functional co-monomers include vinyl trimethoxy silane, vinyl triethoxy silane methacryloxy propyl trimethoxy silane, vinyl dimethoxy methyl silane, methacryloxy propyl triethoxy silane.
More preferably said acrylic emulsion polymer formulation is provided wherein said emulsion polymer includes crosslinker monomer including di-functional crosslinker monomer/s Hexanediol diacrylate, Butanediol dimethacrylate, ethylene glycol dimethacrylate, allyl methacrylate, diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH).
Accordingly preferably said acrylic emulsion polymer formulation is provided wherein said reactive surfactant includes alkyl ether sulphonate having radical polymerizable group with 10 -20 EO (90% aqueous solution), allyl functional polyoxyethylene ether phosphate with 5-20 EO (20% aqueous solution).
According to a preferred aspect of the present invention there is provided said acrylic emulsion polymer formulation wherein said non-reactive surfactant include anionic non-reactive surfactants are Alkyldiphenyloxide Disulfonate sodium salt, Disodium ethoxylated alcohol (C10-C12) half ester of sulfosuccinic acid, Fatty alcohol polyglycol ether sulphate sodium salt, sodium lauryl sulphate, sodium dodecyl benzene sulphonate, and,
non-ionic surfactants of Alcohol Ethoxylate with 10-40 EO, alkyl phenol ethoxylate with 10-40 EO.
According to an embodiment of the present invention there is provided a process for manufacturing of acrylic emulsion polymer formulation comprising the steps of
(I) Providing in initial reactor charge the following ingredients stagewise: (a) reactive/non-migratory surfactant and chelating monomer for incorporation in the emulsion in levels of at least 3.4 wt.% of the emulsion, OR, (a) (i) reactive/non-migratory surfactant and chelating monomer in the levels of at least 2.55 wt.% of the emulsion & (a) (ii) silane functional co-monomer in the levels of at least 0.4 wt.% of the emulsion;
(b) hydrophobic monomer/s in amounts of 30-50 wt.% of the emulsion;
(c) non-reactive surfactant including non-ionic surfactant in amounts of 1-2.5 wt.% of the emulsion;

(II) preparing pre-emulsion seed including initiator and buffer for adding to initial reactor charge;
(III) preparing pre-emulsion by including said hydrophobic monomers (b) in surfactants that is added stagewise in reactor during manufacturing by maintaining a temperature of 80°±2°C;
(IV) adding digestion catalysts for digestion of reaction towards obtaining said stable acrylic emulsion polymer adapted as a stable emulsion polymer with anti-efflorescence, water and solvent resistance on dry and damped cementitious substrates.

Preferably in said process for manufacturing of acrylic emulsion polymer formulation wherein said stage wise addition of ingredients (a)-(c) comprises stages of
(i) preparing initial reactor charge with de-mineralized water and non-polymerizable/non-reactive sulphonate based anionic surfactant and maintaining at temperature of 80°C;
(ii) adding 5% pre-emulsion seed including initiator, buffer, demineralized water to said reactor charge (i);
(iii) preparing pre-emulsion in a separate pre-emulsion flask as milky white pre-emulsion by including migratory/non-reactive, non-migratory/reactive surfactant, non-ionic surfactant dissolved in de-mineralized water, acrylic/vinyl functional monomers by stirring;
(iv) adding chelating monomer/s and potassium per sulfate initiator into the pre-emulsion of step (iii) to obtain resulting pre-emulsion 5% portion of which resulting pre-emulsion is immediately added into reactor charge (i);
(v) observing for exothermal reaction indicating start of reaction in reactor followed by adding upto 25% of said resulting pre-emulsion in portions for a period of 240 minutes at uniform rate, by maintaining temperature at 80°±2°C;
(vi) after 25% completion of addition of said resulting pre-emulsion into reactor, silane monomer and/ or di-functional cross-linker was added into said reactor;
(vii) continuing addition of remaining 75% of said resulting pre-emulsion in said reactor prior to digestion of said reaction mixture.

More preferably in said process for manufacturing of acrylic emulsion polymer formulation said step (IV) of digestion of the reaction mixture is carried for about 1 hr followed by bringing down temperature of the reaction mixture below 50°C for adding required additives including preservatives and maintaining pH by adding liquor ammonia to obtain therefrom said stable acrylic emulsion polymer.
According to a preferred aspect of the present invention there is provided a process for manufacturing of acrylic emulsion polymer formulation wherein said stagewise addition of ingredients (a)-(c) is done in stages (v)-(ix), alternative to said stages (v) - (vii), as per the following:
stage (v) observing for exothermal reaction indicating start of reaction in reactor is followed by adding upto 25% of said resulting pre-emulsion in portions for a period of 210 minutes at uniform rate, by maintaining temperature at 80°±2°C;
stage (vi) after 25% completion of addition of said resulting pre-emulsion into reactor silane monomer and/ or di-functional cross-linker and/ or portions of hydrophobic monomer are added into said reactor;
stage (vii) after 50% completion of addition of said resulting pre-emulsion into reactor, portions of silane functional monomer, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional chelating monomer were added into said reactor;
stage (viii) after 75% completion of addition of said resulting pre-emulsion into reactor, portions of silane functional crosslinker, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional chelating monomer were added into said reactor the pre-emulsion and addition was continued
stage (ix) continuing addition of remaining said resulting pre-emulsion in said reactor prior to digestion of said reaction mixture.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore, the present invention discloses emulsion polymer formulation of styrene-acrylic/acrylic latex in the presence of phosphorous and/or sulphur based surfactants and non-ionic surfactant in the presnece of chelating monomers showing excellent anti-efflorescence, water resistance along with solvent resistance, particularly MTO resistance attributes. The emulsion polymer based coating formulation also shows good adhesion on dry as well damped cementitious substrate.
According to an embodiment of the present invention is provided styrene-acrylic/acrylic latex formulations for architectural coating comprising at least one hydrophilic chelating monomer and non-migratory surfactant together with one or more hydrophobic monomers including BA, 2-Ethylhexyl acrylate, Styrene, n-butyl methacrylate, cyclohexyl methacrylate, tertiary butyl methacrylate.
Said styrene-acrylic/acrylic latex formulations is provided wherein said at least one hydrophilic chelating monomers includes Methacrylic acid, Acrylic acid, Itaconic acid, Maleic acid, Vinyl phosphonic acid.
Preferably said styrene-acrylic/acrylic latex formulations is stabilized by non- migratory, migratory anionic surfactant, non-ionic surfactant or mixtures thereof. Said styrene-acrylic/acrylic latex formulations is provided resulting in the attributes of excellent water and solvent resistance, particularly MTO resistance, and better adhesion on dry and damped cementitious substrate.
The tabulated results under Table 1 and Table 2 through Table 4 reveals the following:
phosphorous based non-migratory/reactive surfactant for pure-acrylic backbone of polymer as per Example 4 together with non-polymerizable non-ionic surfactant;
phosphorous based non-migratory/reactive surfactant for styrene-acrylic backbone as per Example 5 together with non-polymerizable non-ionic surfactant (vs. Comparative Example 7);
sulphonate based non-migratory/reactive surfactant for styrene-acrylic backbone as per Example 1 together with non-polymerizable non-ionic surfactant;
are all important for the pre-emulsion formulation providing acceptable stability to the pre-emulsion enabling respective effective polymers in presence of chelating monomer, & silane monomer giving excellent anti-efflorescence, water resistance along with solvent resistance, particularly MTO resistance.
However, for pure acrylic system under Examples 2 and 3 in the presence of phosphorous based non-migratory/reactive surfactant when taken together with non-polymerizable non-ionic surfactant and appropriate concentration of chelating monomers (inclduing acid functional monomer and reactive surfactants), but in the complete absence of silane monomer also provides desired anti-efflorescence, MTO resistance and water resistance.

EXAMPLES:

In the synthesis of styrene-acrylic/acrylic latex, conventional hydrophobic monomers and higher concentration of chelating monomers were involved. Additionally, non-migratory surfactants were used for the stabilization of latex. The resulting composition shows excellent anti-efflorescence, water resistance, MTO resistance and adhesion on damp and dry cementitious substrates. Chelating monomers may contain Methacrylic acid, Acrylic acid, Itaconic acid, Maleic acid, Vinyl phosphonic acid, etc with minimum 3.5% based on total monomer content.

A. Common procedure for Examples 2, 3, 4, 6 & 8:
Anionic migratory and/or non-migratory surfactant and de-mineralized water were charged into a kettle fitted with a three necked lid and the assembly was heated to 80°C.
In a separate pre-emulsion flask filled with migratory and/or non-migratory surfactant, non-ionic surfactant dissolved in de-mineralized water, acrylic/vinyl functional monomers were weighed and stirred to form a milky white pre-emulsion (as per table 1). Methacrylic acid and potassium per sulphate were added into pre-emulsion, just prior to addition of 5% Pre emulsion into the reactor kettle. 5% of pre-emulsion was added into reactor followed by addition of buffer solution and potassium per sulphate solution into the reactor. Once, the exotherm is observed indicating the start of reaction, to this reaction mixture, the pre-emulsion was added for a period of 240 minutes, by maintaining the temperature at 80°±2°c. After 25% completion of pre-emulsion, silane monomer, di-functional crosslinker/di-acrylic crosslinker was added into the pre-emulsion and addition was continued. After the completion of pre-emulsion addition, 1 g de-mineralised water was used to flush the peristaltic pump used to pump the pre-emulsion mixture into the reactor. Upon completion of addition, 0.05g sodium formaldehyde sulphoxylate (SFS) in 0.5g de-mineralized water was added to the reaction mixture followed by the addition of mixture of 0.05g tert-butylhydroperoxide dissolved in 0.5g de-mineralized water. The digestion process was completed in one hour. Below 50°C temperature, in reactor vessel, 0.2g in-can preservative was added followed by the pH made alkaline by the addition of liquor ammonia
TABLE NO: 1
Sr. No. Chemical Example 2
Example 3
Example 4
Example 6
Example 8

1 Reactor charge-I (80 deg C)
De-mineralised water 18.00 18.00 18.00 18.00 19.00
Non-polymerizable sulphonate based anionic surfactant 0.20 0.20 0.60 0.60 0.25
2 5% pre-emulsion seed
Buffer 0.12 0.12 0.15 0.15 0.15
De-mineralised water 3.00 3.00 2.30 2.30 2.30
Initiator 0.11 0.11 0.15 0.15 0.15
De-mineralised water 3.00 3.00 2.50 2.50 2.50
3 Pre-emulsion
De-mineralised water 22.00 22.00 21.13 21.13 20.00
Phosphorus based non-migratory Surfactant 1.40 1.40 1.25 1.25 -
Phosphorus based migratory Surfactant - - - - 0.50
Non-polymerizable sulphonate based anionic surfactant 0.40 0.40 - - 0.20
Non-polymerizable non-ionic surfactant 0.50 0.50 0.50 0.50 0.50
Methyl Methacrylate 26.00 26.00 27.50 28.00 17.00
2-Ethyl hexyl acrylate 18.50 18.50 18.50 18.00 16.00
Styrene - - - - 10.00
Methacrylic Acid 2.00 0.80 0.80 1.00
Itaconic Acid - 2.00 - - -
Phosphate functional monomer - - 0.50 0.50 -
Hydroxy Ethyl Methacrylate - - - - 1.50
Chain transfer agent 0.03 0.03 0.03 0.03 -
Coalescing solvent - - - - 1.00
Initiator 0.10 0.10 0.05 0.05 -
4 Pre-emulsion Addition stage (feed over 240 minutes at uniform rate)
5 After 25% pre-emulsion addition
Silane Monomer - - 0.40 - 1.00
di-functional crosslinker 0.20 0.20 - 0.20 -
De-mineralised water 0.20 0.20 0.20 0.20 0.40
6 De-mineralised water
For flushing 1.00 1.00 1.00 1.00 1.00
7 Digestion catalysts
Tertiary butyl hydroperoxide 0.05 0.05 0.05 0.05 0.05
De-mineralised water 0.50 0.50 0.50 0.50 0.50
Sodium formaldehyde Sulphoxylate 0.05 0.05 0.05 0.05 0.05
De-mineralised water 0.50 0.50 0.50 0.50 0.50
8 Additives
Biocide 0.20 0.20 0.20 0.20 0.20
Defoamer 0.02 0.02 0.02 0.02 0.02
Ammonia 1.00 1.00 0.50 0.50 0.70
De-mineralised water 0.92 0.92 3.12 3.32 3.68

B. Common procedure for Examples 1, 5, 7:
Anionic migratory surfactant and de-mineralized water were charged into a kettle fitted with a three necked lid and the assembly was heated to 80°C.
In a separate pre-emulsion flask filled with migratory and non-migratory surfactant (phosphate based and/or sulphonate based) and/or non-ionic surfactant dissolved in de-mineralized water, acrylate/vinyl functional monomers were weighed and stirred to form a milky white pre-emulsion (as per table 2). Methacrylic acid and potassium per sulfate were added into pre-emulsion, just prior to addition of 5% Pre emulsion into the reactor kettle. 5% of pre-emulsion was added into reactor followed by addition of sodium bicarbonate solution and potassium per sulphate solution into the reactor. Once, the exotherm is observed indicating the start of reaction, to this reaction mixture, the pre-emulsion was added for a period of 210 minutes, by maintaining the temperature at 80°±2°c. After 25% completion of pre-emulsion, silane functional crosslinker, and/or hydrophobic monomer, and/or di-functional crosslinker were added into the pre-emulsion and addition was continued. After 50% completion of pre-emulsion, silane functional monomer/ crosslinker, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional monomer were added into the pre-emulsion and addition was continued. 75% completion of pre-emulsion, silane functional crosslinker, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional monomer were added into the pre-emulsion and addition was continued. After the completion of pre-emulsion addition, 1 g de-mineralised water was used to flush the peristaltic pump used to pump the pre-emulsion mixture into the reactor. Upon completion of addition, 0.1g sodium formaldehyde sulphoxylate (SFS) in 0.8g de-mineralized water was added to the reaction mixture followed by the addition of mixture of 0.1g tert-butylhydroperoxide dissolved in 0.8g de-mineralized water. The digestion process was completed in one hour. Below 50°C temperature, in reactor vessel, 0.2g in-can preservative was added followed by the pH made alkaline by the addition of liquor ammonia.

TABLE NO: 2
Sr. No. Chemical Example 1
Example 5
Example 7

1 Reactor charge-I (80 deg C)
De-mineralised water 18.00 16.50 18.00
Non-polymerizable sulphonate based anionic surfactant 0.20 0.20 0.15
2 5% pre-emulsion seed
Buffer 0.12 0.12 0.12
De-mineralised water 3.00 3.00 3.00
Initiator 0.11 0.11 0.11
De-mineralised water 3.00 3.00 3.00
3 Pre-emulsion
De-mineralised water 16.21 14.77 18.78
Sulphonate based non-migratory Surfactant 0.34 - 0.34
Phosphorus based non-migratory surfactant - 1.40 -
Non-polymerizable sulphonate based anionic surfactant 0.30 0.30 0.30
Non-polymerizable non-ionic surfactant 0.50 0.50 -
Methyl Methacrylate 6.00 13.50 5.80
2-Ethyl hexyl acrylate 14.70 13.3 14.70
Styrene 11.60 11.50 13.30
n-Butyl Methacrylate 6.00 - 6.00
Methacrylic Acid 1.00 1.20 1.00
Coalescing solvent 0.30 0.50 -
Initiator 0.10 0.10 0.10
4 Pre-emulsion Addition stage (feed over 210 minutes at uniform rate)
5 After 25% pre-emulsion addition
Silane Monomer 0.60 - -
Styrene 2.00 - 2.00
N-Butyl Methacrylate - 2.00 -
De-mineralised water 0.50 0.20 -
6 After 50% pre-emulsion addition
Styrene 2.00 2.00
Silane monomer 0.40 0.60
Phosphate functional monomer 0.70 - -
N-Butyl Methacrylate - 2.00 -
Difunctional crosslinker - 0.22 -
De-mineralised water 1.50 1.50 0.20
7 After 75% pre-emulsion addition
Difunctional crosslinker 0.50 -
Phosphate functional monomer - 0.50 -
Styrene 2.00 - 2.00
N-Butyl Methacrylate - 2.00 -
De-mineralised water 0.50 1.70 -
6 De-mineralised water For flushing 1.00 0.90 1.00
7 Digestion catalysts
Tertiary butyl hydroperoxide 0.10 0.10 0.10
De-mineralised water 0.50 0.70 0.50
Sodium formaldehyde suphoxylate 0.10 0.10 0.10
De-mineralised water 1.50 0.70 1.50
8 Additives
Biocide 0.20 0.20 0.20
Defoamer 0.02 0.02 0.02
Ammonia 0.80 0.90 0.50
2-amino-2-methyl-1-propanol (95%) - - 0.70
De-mineralised water 4.00 6.00 4.00

Characterization and Performance Properties of emulsion samples:
TABLE NO: 3
Sr. No. Test Description Ex 1 Ex 2
Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8
1 Initial viscosity g/cP 92/
322 73/
228 64/184 70/
213 90/
312 71/
218 71/
218 66/
194
2 Accelerated Stability Viscosity after 30 Days at 50 oC Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass

3 Electrolytic stability For 100g sample with 5% Al. Sulphate soln) 28 18 28 20 26 16 25 20
4 Initial pH 7.50 7.12 7.5 7.12 7.60 8.10 8.01 8.69
5 MFFT 21 34 22 31 30 22 22 26
6 Particle size (nm) 119 139 139 107 126 106 129 123
7 Zeta Potential -52.6 -55.1 -54.1 -46.1 -60.9 -51.5 -47.7 -62.3
8 Mechanical resistance 14000 RPM for 10 min (grit <1g in 100g) Pass Pass Pass Pass Pass Pass Pass Pass
9 Stability of an emulsion polymer (shelf life) 180 days 180 days 180 days 180 days 180 days 180 days 180 days 180 days

C. Preparation of coating composition:
Processed emulsions were used to prepare coating as a binder. General coating composition preparation was carried out by following steps like addition of non-reactive hydrophobic additives, addition of dispersing agent, pigment loading and dispersion followed by biocide & coalescing agent addition. This mill base slurry was used for final paint preparation by mixing emulsion in it. These coating compositions were used to check water resistance and solvent resistance performance on cementitious substrate. Coating compositions are named as CC-1 to CC-8 using emulsions from examples no. 1 to 8 respectively.
TABLE NO: 4
Sr. No Test Description CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 CC-7 CC-8
Emulsion used Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8
1 Hydrostatic Pressure on dry substrate (ASTM D 7088) 4.5 Bar 4.5 Bar 4.5 Bar 2.5 Bar 2 Bar 3.5 Bar 3.5 Bar 3.5 Bar
2 Negative capillary
On wet substrate (70% moisture content) (60 Days) Passes Passes Passes Passes Passes Passes Passes Fails
3 MTO tolerance ISO 2812 4 4 3.5 4 4 1 1 4

It was found by the present invention that polymerizable reactive non-migratory surfactant such as sulphonate and phosphorous based reactive and polymerizable non-migratory surfactant when involved for emulsion polymerization together with non-ionic surfactant based on a combination of select monomers with chelating groups such as methacrylic acid, itaconic acid together with select hydrophobic polymerizable monomers including monomers of BA, 2-Ethylhexyl acrylate, n-butyl methacrylate, cyclohexyl methacrylate, tertiary butyl methacrylate, with or without styrene as a monomer selectively provides for a emulsion polymer with dual attributes of solvent resistant (such as being MTO resistant), as well as water resistant along with anti-efflorescence when the chelating monomers including reactive surfactants are involved in select higher levels. Such afore mentioned monomers and reactive surfactants even while involving select lower levels of chelating monomers of itaconic acid, methacrylic acid when reacted together with silane monomer with or without styrene as monomer in combination could also still provide for excellent anti-efflorescence, water resistant and solvent resistant activities as per Example 4. Significantly and added to the above, the polymer of the present invention further provides good adhesion on both dry and damped cementitious substrates. The ASTM D 7088 test method is a test to judge a sample for water resistance withstanding the water pressure at certain level as in Table 4 above, correlatable to good adhesion, with the failure pattern indicated by peel off.
The chelating group such as phosphate and carboxylate present in the form of reactive surfactant or as chelating monomer forms co-ordinate bond with Ca2+ of cementatious substrates. Minimum concentration of chelating group required is found to be 3.4 % by wt. of the emulsion, when free of silane monomer to achieve all the desired properties, which in comparative Example 6 is only about 2.55% hence remaining unable to attain the desired properties.
These co-ordination linkage helps to improve anti-efflorescence, water and solvent resistance as well as adhesion towards cementatious substrates. The polymerizable surfactant containing chelating group and chelating monomers possibly act as a crosslinker between polymer and cementatious substrates.
Further to the above solvent resistance can also be achieved by using non-chelating hydrophilic monomers such as hydroxy ethyl methacrylate but such hydrophilic monomers deteriorate water resistance properties as seen in the Example 8.
Also smooth polymerization processing, higher yield (>99%), and emulsion stability was not achieved without use of non-polymerizable anionic and non-polymerizable non-ionic surfactant. Therefore, non-polymerizable anionic and non-polymerizable non-ionic surfactant appeared essential in the emulsion polymer of present coating composition.

To balance the hydrophilic-hydrophobic nature, phosphate functional monomer together with phosphorous based reactive surfactant only in pure acrylic backbone when further involved together with silane monomer could provide further improved good anti-efflorescence, water and solvent resistance as per Example 4 vs. Example 6 of Table 1 and as reflecting in Table 4.
Whereas sulphonate based reactive surfactant was involved with only styrene-acrylic polymer together with silane monomer to provide good anti-efflorescence, water resistance and good solvent resiatance properties as per Example 1 of Table 2 and as reflecting in Table 4. Both the reactive surfactants give acceptable pre-emulsion stability only in respective polymeric systems and in presence of essential non-polymerizable non-ionic and/ or anionic surfactants.
The appropriate concentration of these chelating polymerizable groups (either from surfactant or chelating monomer) is the uniqueness of the present invention without which select ranges stable emulsion polymer providing desired properties could not be attained.
Also, the ranges of the ingredients employed across the process are completely workable to provide for the desired emulsion except for the comparatives and also remain workable for all the variants of the ingredients mentioned including chelating monomers, hydrophobic monomers, silane functional monomers, crosslinkers, when employed in select wt.% ranges and when select process steps and parameters are followed.
It is thus possible for the present invention to provide for acrylic emulsion polymer and architectural coating formulations thereof that are fortified with excellent anti-efflorescence, water resistance as well as solvent resistance particularly mineral turpentine oil (MTO) resistance characteristics. Selectively improved synthetic methodology of styrene-acrylic/acrylic latex for architectural coating including at least one hydrophilic chelating monomer is also provided.
, Claims:We Claim:
1. An acrylic emulsion polymer and architectural coating formulation thereof comprising (a) reactive/non-migratory surfactant and chelating monomer in the levels of at least 3.4 wt.% of the emulsion, OR, (a) (i) reactive/non-migratory surfactant and chelating monomer in the levels of at least 2.55 wt.% of the emulsion & (a) (ii) silane functional co-monomer in the levels of at least 0.4 wt.% of the emulsion;
(b) hydrophobic monomer/s in amounts of 30-50 wt.% of the emulsion;
(c) non-reactive surfactant including non-ionic surfactant in amounts of 1-2.5 wt.% of the emulsion;
adapted for stable emulsion polymer with anti-efflorescence, water and solvent resistance on dry and damped cementitious substrates.
2. The acrylic emulsion polymer formulation as claimed in claim 1 wherein said reactive/non-migratory surfactant of component (a) is present in the levels of 1.0 to 4.0 wt.% of the emulsion.
3. The acrylic emulsion polymer formulation as claimed in claims 1 or 2 wherein said chelating monomer of component (a) is present in the levels of 1.0 to 2.5 wt.% of the emulsion.
4. The acrylic emulsion polymer formulation as claimed in claims 1-3 wherein said (a) (i) reactive/non-migratory surfactant and chelating monomer in the final emulsion are incorporated in the levels of 1.0 to 4.0 and 1.0 to 2.5 wt.% of the emulsion respectively & (a) (ii) silane functional co-monomer is present in the levels of in the levels of 0.40-0.60 wt.% of the emulsion.
5. The acrylic emulsion polymer formulation as claimed in claims 1-4 wherein said reactive and non-reactive surfactants include phosphorous/sulphur based non-migratory and/ or migratory surfactant/s;
said chelating monomer/s are selected from Methacrylic acid, acrylic acid, Itaconic acid, Maleic acid, phosphate functional monomer including Vinyl phosphonic acid, phosphate;
said hydrophobic monomers includes butyl acrylate (BA), 2-Ethylhexyl acrylate, Styrene, n-butyl methacrylate, cyclohexyl methacrylate, tertiary butyl methacrylate;

said silane functional co-monomers include vinyl trimethoxy silane, vinyl triethoxy silane methacryloxy propyl trimethoxy silane, vinyl dimethoxy methyl silane, methacryloxy propyl triethoxy silane.
6. The acrylic emulsion polymer formulation as claimed in claims 1-5 wherein said emulsion polymer includes crosslinker monomer including di-functional crosslinker monomer/s Hexanediol diacrylate, Butanediol dimethacrylate, ethylene glycol dimethacrylate, allyl methacrylate, diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH).
7. The acrylic emulsion polymer formulation as claimed in claims 1-6 wherein said reactive surfactant includes alkyl ether sulphonate having radical polymerizable group with 10-20 EO (90% aqueous solution), allyl functional polyoxyethylene ether phosphate with 5-20 EO (20% aqueous solution).

8. The acrylic emulsion polymer formulation as claimed in claims 1-7 wherein said non-reactive surfactant include anionic non-reactive surfactants are Alkyldiphenyloxide Disulfonate sodium salt, Disodium ethoxylated alcohol (C10-C12) half ester of sulfosuccinic acid, Fatty alcohol polyglycol ether sulphate sodium salt, sodium lauryl sulphate, sodium dodecyl benzene sulphonate, and,
non-ionic surfactants of Alcohol Ethoxylate with 10-40 EO, alkyl phenol ethoxylate with 10-40 EO.

9. A process for manufacturing of acrylic emulsion polymer formulation as claimed in claims 1-8 comprising the steps of
(I) Providing in initial reactor charge the following ingredients stagewise: (a) reactive/non-migratory surfactant and chelating monomer for incorporation in the emulsion in levels of at least 3.4 wt.% of the emulsion, OR, (a) (i) reactive/non-migratory surfactant and chelating monomer in the levels of at least 2.55 wt.% of the emulsion & (a) (ii) silane functional co-monomer in the levels of at least 0.4 wt.% of the emulsion;
(b) hydrophobic monomer/s in amounts of 30-50 wt.% of the emulsion;
(c) non-reactive surfactant including non-ionic surfactant in amounts of 1-2.5 wt.% of the emulsion;

(II) preparing pre-emulsion seed including initiator and buffer for adding to initial reactor charge;
(III) preparing pre-emulsion by including said hydrophobic monomers (b) in surfactants that is added stagewise in reactor during manufacturing by maintaining a temperature of 80°±2°C;
(IV) adding digestion catalysts for digestion of reaction towards obtaining said stable acrylic emulsion polymer adapted as a stable emulsion polymer with anti-efflorescence, water and solvent resistance on dry and damped cementitious substrates.
10. The process for manufacturing of acrylic emulsion polymer formulation as claimed in claim 9 wherein said stagewise addition of ingredients (a)-(c) comprises stages of
(i) preparing initial reactor charge with de-mineralized water and non-polymerizable/non-reactive sulphonate based anionic surfactant and maintaining at temperature of 80°C;
(ii) adding 5% pre-emulsion seed including initiator, buffer, demineralized water to said reactor charge (i);
(iii) preparing pre-emulsion in a separate pre-emulsion flask as milky white pre-emulsion by including migratory/non-reactive, non-migratory/reactive surfactant, non-ionic surfactant dissolved in de-mineralized water, acrylic/vinyl functional monomers by stirring;
(iv) adding chelating monomer/s and potassium per sulfate initiator into the pre-emulsion of step (iii) to obtain resulting pre-emulsion 5% portion of which resulting pre-emulsion is immediately added into reactor charge (i);
(v) observing for exothermal reaction indicating start of reaction in reactor followed by adding upto 25% of said resulting pre-emulsion in portions for a period of 240 minutes at uniform rate, by maintaining temperature at 80°±2°C;
(vi) after 25% completion of addition of said resulting pre-emulsion into reactor, silane monomer and/ or di-functional cross-linker was added into said reactor;
(vii) continuing addition of remaining 75% of said resulting pre-emulsion in said reactor prior to digestion of said reaction mixture.

11. The process for manufacturing of acrylic emulsion polymer formulation as claimed in claims 9 wherein said step (IV) of digestion of the reaction mixture is carried for about 1 hr followed by bringing down temperature of the reaction mixture below 50°C for adding required additives including preservatives and maintaining pH by adding liquor ammonia to obtain therefrom said stable acrylic emulsion polymer.

12. The process for manufacturing of acrylic emulsion polymer formulation as claimed in claims 9-11 wherein said stagewise addition of ingredients (a)-(c) is done in stages (v)-(ix), alternative to said stages (v) - (vii), as per the following:
stage (v) observing for exothermal reaction indicating start of reaction in reactor is followed by adding upto 25% of said resulting pre-emulsion in portions for a period of 210 minutes at uniform rate, by maintaining temperature at 80°±2°C;
stage (vi) after 25% completion of addition of said resulting pre-emulsion into reactor silane monomer and/ or di-functional cross-linker and/ or portions of hydrophobic monomer are added into said reactor;
stage (vii) after 50% completion of addition of said resulting pre-emulsion into reactor, portions of silane functional monomer, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional chelating monomer were added into said reactor;
stage (viii) after 75% completion of addition of said resulting pre-emulsion into reactor, portions of silane functional crosslinker, and/or hydrophobic monomer, and/or di-functional crosslinker, and/or phosphate functional chelating monomer were added into said reactor the pre-emulsion and addition was continued
stage (ix) continuing addition of remaining said resulting pre-emulsion in said reactor prior to digestion of said reaction mixture.

Dated this the 2nd day of May, 2023 Anjan Sen
Of Anjan Sen and Associates
Applicants Agent
IN/PA-199