SURFACTANT STABILIZED VAM-VEOVA10 TERPOLYMER BASED EMULSION WITH GOOD FREEZE THAW STABILITY AND A PROCESS THEREOF

Abstract

A surfactant stabilized vinyl acetate ter-polymer based emulsion is provided comprising surfactant combination based freeze thaw stabilized vinyl acetate ter-polymer emulsion wherein said surfactant combination comprises non-ionic surfactant in combination with at least two polymerizable anionic reactive surfactants. A process of manufacturing the said emulsion is also provided, which process in comprising of selective sequence based steps and upon employing selective amounts of ingredients provides for said freeze thaw stable emulsion that is freeze thaw stable upto at least 5 cycles of freezing and thawing and yet maintains a particle size of 130-150 nm.

Claims

1-10. (canceled)

11. Surfactant stabilized vinyl acetate ter-polymer based emulsion comprising surfactant combination based freeze thaw stabilized vinyl acetate ter-polymer emulsion wherein said surfactant combination comprises non-ionic surfactant in combination with at least two polymerizable anionic reactive surfactants, said emulsion being freeze thaw stable and also having a particle size of 130-150 nm.

12. The emulsion according to 11 that is freeze thaw stable up to at least 5 cycles of freezing and thawing.

13. The emulsion according to claim 11 wherein said polymerizable anionic reactive surfactants are selected to be polymerizable and react with monomers to be covalently bonded with the monomers and are preferably selected from acrylamide derivative of 2-acrylamido 2-methyl-propan sulphonic acid-sodium salt (AMPSS) and surfactant of Formula (I) below ##STR00006## Where R is alkyl group, X is SO.sub.3NH.sub.4, SO.sub.3Na, n=10;

14. The emulsion according to claim 11 comprising non-ionic surfactant in the levels of 0.2 to 0.5 wt % which is non-ionic fatty alcohol having ethylene oxide content of 19-20 moles.

15. The emulsion according to claim 11 wherein said vinyl acetate based emulsions comprises Vinyl acetate-VeoVa10-Butyl acrylate ter-polymers, Vinyl acetate-VeoVa10 copolymers.

16. The emulsion according to claim 11 obtained of reacting monomers of Vinyl acetate, VeoVa10, Butyl acrylate and at least two polymerizable anionic reactive surfactants including 2-acrylamido 2-methylpropan sulphonic acid-sodium salt (AMPSS) and a surfactant of formula (I) in a pre-emulsion medium comprising non-ionic surfactant whereby 2-acrylamido 2-methylpropane sulphonic acid-sodium salt (AMPSS) is added into AMPSS free pre-emulsion seed to favour AMPSS reaction with said monomers and avoiding homo polymerization.

17. A process for the preparation of the surfactant stabilized vinyl acetate ter-polymer based emulsion of claim 11 comprising a freeze thaw characteristic imparting surfactant combination of at least two reactive polymerizable anionic surfactants including surfactant of Formula (I) below ##STR00007## Where R is alkyl group, X is SO.sub.3NH.sub.4, SO.sub.3Na, n=10; an acrylamide derivative of 2-acrylamido 2-methylpropan sulphonic acid-sodium salt (AMPSS) and a non-ionic surfactant and wherein said surfactants of said surfactant combination are reacted selectively in a 2-acrylamido 2-methylpropan sulphonic acid-sodium salt (AMPSS) free seed pre-emulsion of monomers comprising Vinyl acetate-VeoVa10-Butyl acrylate or Vinyl acetate-VeoVa10, along with methacrylic acid preferably about 5% by wt. of the pre-emulsion having the surfactant of Formula (I) along with said non-ionic surfactant followed by subsequent addition of said 2-acrylamido 2-methylpropan sulphonic acid-sodium salt (AMPSS) to favour freeze thaw stability of the emulsion without affecting the reaction rate of the monomers in said emulsion and facilitating reaction of AMPSS with monomers in said pre-emulsion by avoiding unwanted homo-polymerization reactions.

18. A process according to claim 17 comprising the steps of (I) providing reactor charge of non-ionic surfactant together with potassium persulphate and water; (II) providing said pre-emulsion comprising (a) polymerizable anionic reactive surfactants including surfactant of Formula (I) below ##STR00008## Where R is alkyl group, X is SO.sub.3NH.sub.4, SO.sub.3Na, n=10; (b) non-ionic surfactant in the levels of 1 to 1.2 wt % which is a non-ionic fatty alcohol having ethylene oxide content of 19-20 mole; (c) monomers of Vinyl acetate, VeoVa10, Butyl Acrylate; (d) methacrylic acid and potassium persulphate; (e) 2-Acrylamid 2-Methylpropan Sulphonic Acid-Sodium (AMPSS) and adhesion promoter I; (f) adhesion promoter II and obtaining therefrom said vinyl acetate ter-polymer based emulsion composition.

19. A process according to claim 18 wherein providing ingredient (d) of methacrylic acid and potassium persulphate in the pre-emulsion is accomplished just prior to addition of 5% Pre-emulsion in the reaction vessel; providing ingredient (e) of 2-Acrylamido 2-Methylpropan Sulphonic Acid-Sodium (AMPSS) and adhesion promoter I in the pre-emulsion is effected post addition of 5% of the pre-emulsion free of AMPSS as seed in the reaction vessel to favour AMPSS reaction with said monomers by avoiding homo polymerization reactions; providing ingredient (f) of adhesion promoter II is carried out after completion 80% of addition of the remaining pre-emulsion in the reaction vessel.

20. A process according to claim 18 wherein the anionic reactive surfactant of Formula (I) is provided in the levels of 0.3 to 0.4 wt % on monomer solids and a non-ionic surfactant of alcohol ethoxylates with 19-20 mole ethoxylation is provided 1 to 1.2 wt % and 2-acrylamido propane sulfonic acid sodium salt (AMPSS) is provided at the levels of 0.8-1.2 wt % on monomer solids in said pre-emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0048] As discussed hereinbefore the present invention provides for a surfactant stabilized vinyl acetate ter-polymer based emulsion comprising surfactant combination based freeze thaw stabilized vinyl acetate ter-polymer emulsion wherein said surfactant combination comprises non-ionic surfactant in combination with at least two polymerizable anionic reactive surfactants. A process for manufacture of said emulsion is provided that is freeze thaw stable together with a particle size of 130-150 nm.

[0049] Usually anionic surfactants are predominantly used in the reactor in emulsion polymerization processes and use of non-ionic surfactants slows down the reaction rates of the monomers.

[0050] Importantly, it was found by way of the present invention that the non-ionic surfactant in combination with at least two reactive anionic surfactant is one of the key parameters to get freeze thaw stability which when present in amounts of 0.2 wt % offers freeze thaw stability without affecting the reaction rate of the monomers when present in combination with at least two reactive anionic surfactants.

[0051] According to an embodiment of the present invention following are the basic and optional process features:

Example 1

[0052] In the Reactor: (A) [0053] 1. Demineralized water—19-21 wt % [0054] 2. Non-ionic surfactant (alcohol ethoxylates with 19-20 mole ethoxylation—0.1-0.3 wt % [0055] 3. Potassium per sulphate—0.025-0.075 wt %

[0056] Pre-Emulsion: (B) [0057] 1. Demineralized water—21-23 wt % [0058] 2. Polymerizable anionic reactive surfactant *−0.3-0.4 wt % [0059] Polymerizable anionic reactive surfactant * has the following structure;

##STR00005##

[0060] Where R is alkyl group, X is SO.sub.3NH.sub.4, SO.sub.3Na, n=10 [0061] 3. Non-ionic surfactant (alcohol ethoxylates with 19-20 mole ethoxylation)-1 to 1.2 wt % [0062] 4. Sodium bi carbonate—0.1-0.3 wt % [0063] 5. Potassium per sulphate—0.1-0.2 wt % [0064] 6. Vinyl acetate—33-35 wt % [0065] 7. VeoVa10—8-10 wt % [0066] 8. Butyl acrylate—4-6 wt % [0067] 9. Glacial Methacrylic acid—0.1 to 0.2 wt % [0068] 10. 2-Acrylamido propane sulphonic acid-Sodium salt (anionic polymerizable surfactant) **−0.8 to 1.2 wt % in pre-emulsion. [0069] 11. Adhesion promoter I—0.05-0.1 wt % [0070] 12. Adhesion promoter II—0.3-0.5 wt %

[0071] Digestion C: [0072] 1. Tertiary butyl hydroperoxide—0.05-0.07 wt % [0073] 2. Sodium formaldehyde sulphoxylate—0.04 to 0.06 wt %

[0074] Additives: [0075] 1. Biocide—0.2 wt % [0076] 2. Water—Balance to get 50% solid

Example 2

[0077] Preparation of Reactor Charge (A)

[0078] Demineralised water was charged at room temperature and stirred. The temperature was raised to 40-50° C. Non-ionic surfactant (alcohol ethoxylates with 19-20 mole ethoxylation) was then charged and flushed with Demineralised water. Potassium PerSulfate was charged and flushed with water.

[0079] Preparation of Monomer Pre-Emulsion (B)—

[0080] Demineralised water was charged and stirring was started. Polymerizable anionic reactive surfactant * of the structure represented above was charged, first it was allowed for dissolution and then Non-ionic surfactant (alcohol ethoxylates with 19-20 mole ethoxylation) was added and flushed with Demineralised water Sodium bicarbonate was charged and flushed with Demineralised water. Charge Vinyl acetate Monomer, VeoVa10 Monomer, Butyl Acrylate Monomer and was flushed with Demineralised water. Glacial Methacrylic Acid was charged and flushed with Demineralised water, Potassium per sulphate solution was prepared in Demineralised water and charged.

[0081] Importantly apart from the selective surfactant combination that leads to the emulsion the process of the present invention to achieve the product emulsion is based on the selective sequence of addition of the ingredients wherein

[0082] i) Methacrylic Acid and Potassium PerSulphate solution are added in the pre-emulsion just prior to the addition of 5% pre-emulsion in the reactor; ii) Pre-emulsion that needs to be added (5%) in the reactor should not contain 2-acrylamido 2-methylpropan sulphonic acid-sodium and adhesion promoter I and the addition of 2-Acrylamido 2 Methylpropan sulphonic acid-sodium and adhesion promoter I is to be done into Pre Emulsion vessel after 5% Pre emulsion addition had been done into the reactor. iii) addition of adhesion promoter II and Demineralised water is carried out about 4 hrs after completion of addition of the remaining pre-emulsion in the reaction vessel.

[0083] The remaining steps are usual emulsion polymerization, conditions involving digestion of the synthesized polymer at 80° C. for 1 hour, followed by cooling, addition of biocide and filtration.

[0084] Surprisingly it was thus found that employing only polymerizable anionic reactive surfactant instead of the above selective combination of surfactants gives an unstable emulsion wherein the emulsion was also found to be unstable when the selective sequence of addition under the process was not followed even though (the selective surfactant combination is used.

[0085] It is thus possible by way of the present invention to provide for surfactant stabilized vinyl acetate ter-polymer based emulsion with superior binding power comprising surfactant combination based freeze thaw stabilized emulsion wherein said surfactant combination comprises non-ionic surfactant in combination with at least two polymerizable anionic reactive surfactants. More particularly, a process for manufacture of said emulsion is also provided comprising selective steps in a selective sequence by employing selective amounts of ingredients that provides said freeze thaw stable emulsion together with a particle size of 130-150 nm in said emulsion.