DESC:Field of the Invention
The present invention relates to development of a pigment dispersion formulation preferably universal carbon black based dispersion/ colorant formulation comprising organometallic compound as an additive together with ethoxylated surfactant that allows incorporation of both economic carbon black and specialty carbon black in water based paint and enamel paints without any drop in tinting strength of paints thereby conferring age/storage stabilityin terms of tinting strength of paints, particularly in solvent based alkyd paint.
Background of the Invention
Since the early civilizationcarbon black enjoys close association with human as acolour and pigment.The techniques for initial application of carbon black in colour ink have been transformed for the modern application in paints and coatings. Specifically with colors, it is very important to reach the exact shade of black.In many applications carbon black is used as a black pigment, to achieve a colour spectrum ranging from gray to deep black. Owing to the variation of shape and size, carbon black can exhibit a range of color properties. Important color properties include jetness, mass tone, and tinting strength. The delicate interaction between primary particle size, surface area, and aggregate size determines the ultimate color. The structure influences the dispersibility of carbon black and thus determines the level of color achievable in the host matrix. By the modification of different carbon black properties it is possible to reach required properties for the final product like tinting strength, viscosity, shade, UV-resistance and dispersibility. Presently surface-modified specialty carbon black grades overcome few of these difficulties with or without pretreatment.
The dispersing of carbon blacks and fillers in organic and aqueous media, that is, the destruction of the agglomerates formed from the primary pigment and filler particles, is a work operation required in the production of paints and other pigmented coating agents, which constitutes a considerable cost factor owing to the necessary expenditure of time and energy. This dispersing operation is performed mechanically by means of various machines such as kneaders, cylinder mills and ball mills. In order to shorten this working operation, the pigments or fillers are treated with organic compounds which are intended to decrease the interfacial tension between the pigment or filler granule and the organic or aqueous medium and thus facilitate the dispersion of the pigment or filler. As far as possible, the action of these organic compounds should be limited only to improving dispersibility without attendant negative phenomena.
Several dispersants have been used for dispersing carbon black including cationicsurfactants, anionic surfactants, and non-ionic surfactants.Cationic surfactants like cetyltrimethylammoniumbromide (CTAB) andcetyltrimethylammonium chloride (CTAC) have been reported to efficiently disperse carbonblack particles. The colloidal stability of the carbon black particles in presence ofCTAB has been attributed to the monolayer adsorption of CTAB, which provides stabilityagainst aggregation through a combination of electrostatic repulsion and steric hindrance. Incorporation of a minor amount of soap of a stable amine-a guanidine (US 1,848,213) is also reported as an aid to disperse carbon black in lacquers, paints and enamels.

In the case of non-ionic surfactants, thehydrophobic groups adsorb strongly on the surface of carbon black, while thesteric stabilization is provided by hydrophilic ethylene oxide (EO) groups. With an increase in number of EO groups in the non-ionic surfactant carbon black colloidal stability increases. In case of nonylphenol ethoxylates with 10 moles of EO per surfactant molecule showed the bestperformance and was attributed to the superior wetting ability of NPE molecule withintermediate number of EO groups grafted.Carbon black dispersions stabilizedwith high molecular weight surfactant resulted in dispersions with higher viscosity thanthose stabilized with low molecular weight surfactant.
Among the anionic surfactants, sodium dodecylbenzene sulfonate (SDBS) is known to be more effective in dispersing carbon black than sodium dodecyl sulfate (SDS) due tobetter wetting nature of SDBS.

Few other prior arts related to the present invention are summarized as follows:

US10577512B2 relates to solvent borne alkyd paint composition containing a universal colorant (TEGO ® Dispers 653-Dispersant- modified polyether, TEGO ® Defoamer 810, can act as preservative along with pigment and water) of organic pigment or inorganic pigment, a solvent borne alkyd base paint and a fatty acid amidoamine, where the fatty acid amidoamine is the condensation product of a fatty acid or their corresponding ester or fatty oil and a polyamine, the polyamine is an aliphatic polyamine having an amine functionality of at least 2, and the polyamine contains at least one primary amine group and at least one tertiary amine group.

CN107636092(A)discloses general no fat mill base comprised of dispersant and nanometer general color paste; preparation of dispersant involving hydrophobic monomer, hydrophilic monomer, functionalmonomer, initiator, environmentally friendly solvent and preparation method thereof. Nanometer general color paste isprepared using toner, dispersant, NMF, defoamer, anti-settling agent, bactericide,deionized water as raw material. The dispersant is applied to various water-based resin free color pastes, and stability of pigment paste is good, particle diameteris in nanoscale, has efficient scatter and antiflocculation, low viscosity and storage stability.

US 2017/0174924 A1 discloses a low VOC universal colorant composition for both solvent-based and water-based paintsand coatings showinggood stability with respect toviscosity, pH, and Hegman grind over time. The colorant composition is used to tint a basepaint formulation which, after tinting, shows a desirable rheological profile and optimalblock and tack resistance relative to base paints tinted using standard colorant lines. The universal colorant composition, comprisingless than about0.1 wt % alkylphenol ethoxylate surfactants;a universal surfactant package compatible with latex-based and alkyd-based compositionsand with compositions comprising polymeric material or alkoxy substituted polymeric material and preferably poly ether (PEG), polyhydric alcohol along with associative thickeners and other ingredients.

US6287377B1 revealed a universal tinting concentrate for both solvent- and water-based paints and coatings. Theuniversal tinting concentrate is a composition which includes a colorant component, suchas pigment, colorant, tinting agent and/or metal effect agent; a pigment dispersantcomprising an organic acid containing lesserthan 70 carbon atoms including cyclic di or multi acid or derivatives; and a pH-neutralizing agent.

CN105885324A teaches preparation ofblack masterbatch with maleic anhydride modified polypropylenecarrier resin and dispersion having a formula of R1-R2-R3 wherein said R1 is selected fromany one of polyethylene glycol, polyvinyl alcohol, and glycerine, said R2 is polyacrylate andR3 is any one of perfluorobutyl, perfluoropentyl, and perfluorohexyl.

PBA-b-PDMAEA and PEO-b-PAA block copolymer synthesized by Guo, Hongtao et al.[TuliaoGongye 2010, 40(2),22-26 and JingxiHuagong 2010, 27(1), 26-29, 56] respectively prepared by RAFT polymerization showed suitability for dispersion ofcarbon black, inorganic and organic pigments. EspeciallyPEO-b-PAA block polymer showed excellent dispersion of carbon black, inorganic and organic pigments and both of themare suitable to act as a universal dispersant. Belding, Sheila et al., [Surface Coatings Australia 2004, 41(6), 16-20]disclosed the liquid dispersant flow point method (LDFPM) tomaximize the pigment concentration of a color mill base by first determining the optimumdispersant concentration, and then minimizing the liquid concentration. Two dispersants,Troysperse 90W and Exptl.-02/C black, were compared to illustrate LDFPM, and a universaldispersant was introduced.

CN112341925A teaches anti-sagging solvent-free single-component polyurethane waterproof coating comprising of polyetherpolyol, diphenylmethane diisocyanate, plasticizer (diisononylphthalate, chlorinated paraffin wax, etc.), 40-45 parts of pigment and filler (calciumcarbonate, carbon black, etc.), defoaming agent and 0.51-1.02part of compound catalyst (di-Bu tin dilaurate, zinc 2-ethylhexanoate) and rheology aid (micronized polyamide wax, 1,3-bisaminomethylcyclohexane 12- hydroxystearic acid, etc.) and preparation method thereof.

CN108587319A disclosesa wood wax-based ink comprising of lacquer seed emulsion, lacquer seed nucleolus oil, water-solubleacrylic resin, Tung oil, inorganic pigment, 0.6-3 parts ofdesiccant, and 0.2-1 part of titanate coupling agent.Zinc 2-ethylhexanoate or mixture of metal salts is used as desiccant to a wood wax-based ink –yielding fast drying coating composition having, excellent rheology. However Zinc is used as a desiccant and does not indicate stability of tinting strength

JP2018123188Adivulged oil-based ink-jet ink capable of reducing wetting of a nozzle plate, increasing imagedensity, and reducing strikethrough wherein the oil-based ink-jet ink contains a pigment, a water-insoluble resin, a water-soluble resin containing an amino group, a monovalent ordivalent metal salt (preferably zinc) of an aliphatic monocarboxylic acid, and a non-aqueous solvent. However,Zinc salt of monocarboxylic acid is used to reduce wetting.

CN102634272Arelates to rapid-drying paint for car comprising a paint component and acuring agent component and its preparation method. The paint component includes resin (acrylic resin, saturatedpolyester resin, and/or polyurethane resin), pigment (high pigment carbon black,titanium dioxide, organic perylene red etc.) 5-35, auxiliary agent (zinc 2-ethylhexanoate, zirconium 2-ethylhexanoate, or dibutyltin dilaurate) 0.5-5, and solvent(Bu acetate, propylene glycol Me ether acetate, and/or cyclohexanone; andthe curing agent component includes Bu acetate, and trimer isocyanate.

DE2502282A1 teaches for metal salts of organic acids as driers used in surface-coating compositions that contain drying oils and other oxidizable vehicles to accelerate the drying process and to promote the polymerization of the unsaturated oils to dry, to give mechanically resistant coatings and does not relate to any tinting strength of carbon black dispersion.

US3645765Arelates to carbon black pelleting agent which acts as a pelleting agent to disperse the carbonblack in rubber comprising an aqueous solution of a polyethyoxylated fatty acid.The polyethyoxylated fatty acids of this advancement have the general formula R-CO-O- (CH2CH2O)x H in which x,the moles of ethylene oxide, varies upto 15. Such fatty acids usually havea molecular weight from about 500 to about 1,000, a specific gravity from about 0.9 toabout 1.1 and may be either solids or liquids. The alkyl radical, R, is generally derived fromstearic acid, oleic acid, or rosin fatty acids.

US5871706Adisclosed carbon black compositions produced byincorporating ethoxylated esters or polyethers onto fluffy carbon black in a pelletizingprocess to produce free flowing, low dust, attrition resistant carbon black pellets which areeasily dispersible in most polymeric systems.

WO2019193597A1 involves clear mixture of two non-ionic surfactant selected from the group consisting of alkoxylated poly ethers, alkoxylated esters, polyglycol ethers, alcohol alkoxylates or alkylphenol polyglycol ethers with at least one humectant selected from the group consisting of polyhydric alcohol or esters and ethers thereof in water for makinga slurry of carbon black. Although final form of the carbon is different (granules) but it iseasily dispersible.

US10287448B2 provides a universal pigment preparation including aflocculation-stabilizing medium including (a1) reaction products of di- or polycarboxylicacids or hydroxycarboxylic acids with di- or polyols, and (a2) reaction products of alkyleneoxides with alkoxylatable compounds wherein the reaction products (a2) are prepared by an alkoxylation reaction of alkoxylatable compounds, and at least one pigment.

US4398955Arelates to a dispersion of a particulate solid in a polar organic medium in the presence of a dispersingagent which is a tertiary amine or a salt thereof with a mineral acid or an aromaticcarboxylic or sulphonic acid, the amine containing at least one polymeric group which is apoly (lower alkylene oxy) chain or a poly(carbonyl lower alkylene oxy) chain and inks,paints and similar formulations made from such a dispersion.

WO1994007966A1discloses low viscosity acrylic hot melt adhesives involving low viscosity hot melt acrylicpressure sensitive adhesive polymer formed by bulk polymerization of at least one alkylacrylate monomer containing from about 4 to 8 carbon atoms in the alkyl group, and monomers of an amide, acarboxylic acid, and anhydride. Said polymer have long, stable shelf lives at ambient and elevated temperatures alone, and when combined with organometallic compounds, such as carboxylates and resinates of metals having a valence of from 2 to 4 form thermally reversible cross-links which increase viscosity up to about 100 Pa.s or more at 150°C with dramatically higher viscosities at end use temperatures. Zinc octoate is the preferred organometallic compound.

CN107903716A provides a mill base/ pigment concentrate which comprises a lightstabilizer that can shield or absorb the energy of ultraviolet to prevent destructions of color. The mill base is comprised of water, solvent, 21 to 32 parts of surfactant, light stabilizer, pH adjuster, bactericide, defoamer, and 18 to 22 parts of pigments; wherein, the surface active agent includes 2 to 5 parts of wetting agent and 19 to 27 parts of dispersant wherein the solvent includes at least one of acetone, ethanol, propylene glycol, polypropylene glycol, and isopropanol. In order to better disperse the pigments in the paint, addition of a small amount of surfactants and zinc naphthenate during the manufacturing process is also recommended.

Although numerous methods are reported for dispersion of carbon blacks in the coating system- still there exists a need in the art for the development of an additive, addition of which would enable the pigment dispersion formulation preferably universal carbon black pigment dispersion formulation comprising either engineered or economic carbon black, equally suitable for application in coating systems and to attain pigment stabilization in dispersions which is not possibleusing conventional wetting and dispersing agents and that would furtheraid in arresting tinting strength drop after accelerated stability and over shelf life of the paint.

Objectives of the Invention

It is thus the primary objective of the present invention to develop a universal pigment dispersion/formulation capable of incorporating economic carbon black pigmentin coating systems that would be long term storage stable without any drop in tinting strength.
Another preferred objective of the present invention is to develop said universal pigment dispersion formulationby involving additives comprising select transition metal salt in combination with alkyl ethoxide surfactants.
Another objective of the present invention is to develop said universal pigment dispersion formulationwhich would provide improved and stable tinting strength over its shelf life and would arrest drop in tinting strengths particularly in solvent based alkyd paints.
Yet another objective of the present invention is to develop said universal pigment dispersion formulationwhich would be cost effective, and having easy processing steps.
Another objective of the present invention is to develop said universal pigment dispersion formulationwhich would help to provide the same/similar finished product without compromising on quality but ensuring lower raw material cost.
Another objective of the present invention is to develop said universal pigment dispersion formulationwhich would facilitate adding new formulations to the existing product portfolio.

Summary of the Invention
In the primary embodiment present invention is directed to providea pigment dispersion formulation comprising
(a) 11.5 to 14.5wt.% ethoxylated surfactant of hydroxy fatty acid ethoxylate having HLB values in the range of 12-14;
(b)1 to 2 wt. % a transition metal based organometallic compound including Zinc based organometallic compound.

Another embodiment of the present invention is directed to provide said pigment dispersion formulation adapted as universal pigment dispersion formulation for dispersing pigments including specialty carbon black, economic carbon black or combinations thereof in both water based paint and enamel based paint conferring tinting strength shelf life to said paints particularly solvent based alkyd paints.

Another embodiment of the present invention is directed to provide said pigment dispersion formulation wherein said formulation allows incorporation of 7.3 to 9 wt.% pigment preferably carbon black including specialty carbon black or economic grade carbon blackor combinations thereof in said pigment dispersion formulation or paint formulations when the ratio of said (a): (b) is in the range of 8 to 12 allowing shelf life of tinting strength free of any drop in tinting strength in said paints even after accelerated stability tests.

Further embodiment of the present invention is directed to provide said pigment dispersion formulation wherein
said hydroxy fatty acid ethoxylate having HLB value in the range of 12-14 includes castor oil ethoxylate soya oil ethoxylate, groundnut oil ethoxylate either individually or in combination;
saidZn based organometallic compound is salt of carboxylic acid having 2-14 carbon atoms including Zn octoate.

Yet another embodiment of the present invention is directed to provide said pigment dispersion formulation wherein
said hydroxy fatty acid ethoxylate with desired HLB value is castor oil ethoxylate having approximately 36 moles of ethylene oxide per mole of castor oil for attaining the desired HLB value; and
said carbon black is economic grade carbon black and includes engineered carbon black preferably economic grade carbon blacks including Carbon Black ISAF N220, Carbon Black HAF N330, Carbon Black FEF N550 and Carbon Black HFM N660.

Further embodiment of the present invention is directed to provide said pigment dispersion formulation that is compatible with other surfactants employable in said dispersion formulation and paints enabling robust formulation of existing colorantsthat is cost effective being free of said requirement of specialized carbon blacks.

Still further embodiment of the present invention is directed to provide said pigment dispersion formulation allowing incorporation of economic carbon black in said dispersion formulation or paints that displays similar characteristics when incorporated into freshly prepared water based paint and enamel based paint in respect of specialty carbon black whereas %TS remains the same before and after accelerated stability test for water based paint formulation for both the casesand % TS remains the same compared to ~15% reduction of the same for enamel paint involving specialty grade carbon formulation.

Another preferred embodiment of the present invention is directed to provide a process of manufacturing pigment dispersion formulation comprising the steps of
Providing (a) 11.5 to 14.5 wt.% ethoxylated surfactant of hydroxy fatty acid ethoxylate having HLB values in the range of 12-14; (b) 1 to 2 wt. % of a transition metal based organometallic compound including Zinc based organometallic compound;
Premixing, milling and thinningwherein addition of organometallic compound is done in thinning stage to obtain therefrom said pigment dispersion formulation.

Yet another embodiment of the present invention is directed to provide said process of manufacturing pigment dispersion formulation wherein when the organometallic compound is added at thinning stage the ratio of surfactant to organometallic compound is maintained at preferably 12.8:1.5.

Detailed Description of the Invention
As stated hereinbefore, the present invention relates to development of pigment dispersion formulation preferably universal carbon black based pigment dispersion formulation having stable tinting strength over its shelf life upon involving economic grade carbon blacks. Usual carbon black formulation comprises specialty carbon black- which is more expensive and availability of the same is an issue. Specialized carbon blacks are non-rubber grade. It is also named as engineered carbon black which is widely used in paints, coatings and inks to achieve the properties like increased tinting strength, improved jet-ness or blue undertone and improved dispersibility in the final product whereas the economic carbon black are rubber grade pigment.In case of solvent based alkyd paint, universal carbon black dispersion based on economic grade carbon black shows drop in tinting strength on ageing and hence is a problem in the art.Present invention is thus directed to overcome such problems and reduce vulnerability with respect to dependence on a single grade of specialty carbon blackso as to arrest drop in tinting strengths particularly in solvent based alkyd paints. Also, involvement of economic grade carbon black will ensure lower RMC (raw material cost).
In the primary embodiment, the present invention provides pigment dispersion formulation adapted as universal colourant formulation comprising select additives involving unique organometallic compound together with ethoxylated surfactantto confer age stability tosaid pigment dispersion formulation preferably carbon black dispersion more preferably economic grade carbon black based dispersion.
In another embodiment, the present invention provides for said age stable universal colorant dispersionwithout any drop in tinting strength in selectively involving said additive comprising organometallic compound of Zinc together with select alkyl ethoxylated surfactanthaving 12-14 HLB values including castor oil ethoxylate either individually or in combinationwith other ethoxylates including soya oil ethoxylate, groundnut oil ethoxylate.
In another embodiment, the present invention provides said additive wherein said castor oil ethoxylate, preferably iscastor oil based ethoxylated surfactant wherein castor oilis condensed with preferably 36 moles of ethylene oxide per mole of castor oilin combination with organometallic compound of Zincthat arrests drop in tinting strength even after accelerated stabilitytest is performed,which is not possible using conventional wetting and dispersing agents.
In another embodiment said organometallic compound additive includes divalent metal salts of carboxylic acid preferably divalent transition metal salts and more preferably zinc salt.
In another embodiment said organometallic compound additive includes said zinc salts of carboxylic acid wherein said carboxylic acid possess 2-14 carbon atom- more preferably 3-12 carbon atoms.
In another embodiment of the present invention said dispersion formulationis compatible with other surfactants such as fatty acid modified emulsifier in the system/resins to be coloured.
In another embodiment a process of the present invention is provided wherein said Zinc based compound which when specifically involved in milling stage contributes in better wetting and dispersion of pigments. Such process of the invention not only enables bringing in low viscosity and high solids in the dispersion/formulation, but also when select Zinc Octoate Compound together with select ethoxylated surfactant with select moles of ethylene oxide group in select ratio is employed for universalpigment dispersion comprising economic grade carbon black,aids in arresting tinting strength drop even after accelerated stability.For the present invention organometallic compound is added at thinning stagemaintaining theratio of surfactant to organometallic compound 12.8:1.5.
In another embodiment, the present invention provides said age stable universal colorant dispersion/ formulation comprising said Zinc Octoate together with said select ethoxylated surfactant in select ratiois particularly suitable for dispersion of economic grade carbon blacks.
In another embodiment of the present invention provides said age stable universal colorant dispersion/composition suitable for water based, solvent based and mixed water/solventbased paints.
In another embodiment, the present invention provides for said stable universal colorant dispersion/composition that is age stable without any drop in tinting strength when applied in various solvent borne resins particularly alkyd resins.
In another embodiment of the present invention provides universal carbon black based pigment dispersion having stable shelf life using economic grade carbon blacks and thus reduces vulnerability with respect to dependence on a single grade of specialty carbon black, and enables robust formulation of existing colorant with significant cost saving and satisfies wider customer compliance regarding quality of the formulation and also enables addition of new formulation to the list of existing formulation with a cheaper price.

Example-1
To develop a suitable additivefor pigment dispersion formulation/universal carbon black based pigment dispersion formulation capable of incorporating economic grade carbon blacksaid select castor oil ethoxylate surfactants, and transition metal based organometallic compounds were involved. The engineered and economical carbon black was selected from the List of economic carbon black including but not limited to Carbon Black ISAF N220, Carbon Black HAF N330, Carbon Black FEF N550 and Carbon Black HFM N660.

General method of preparation of said formulation comprises the steps of premixing, milling and thinning. Premixing include addition of water, glycols, wetting and dispersing agents, defoamer, in-can preservative and neutralizer at slow speed followed by addition of pigment and extenders in the milling stage. During milling, high speed is maintained to achieve grinding of pigment aggregates to get their individual particle size. Thinning is then continued at medium speed ensuring proper mixing of raw materials which includes water, glycols, dispersing agents & defoamer to get the stable pigment dispersion.

Table-1: % weight of surfactants and organometallic compound additive in formulation preferably involving workable carbon atom range based organometallic compound with 2-14 carbon atoms more preferably Zinc octoate.
Raw Material % Weight
STD Soya oil ethoxylate 15.8
EXPT Castor oil ethoxylate 8-12
18% Zn Octoatewith25% - 36% of Turpentine oil and other ingredients 1.5

Keeping the base formulation same- selective amount of different additives such as anionic polymeric dispersing agent, non-ionic dispersing agent, mixture of ionic and nonionic surface active agent, block copolymer with pigment affinic groups and zinc octoate were added into it to get acceptable formulations. A blank/control formulation was also prepared without adding any additives in the formulation (Table-2).

Table 2: Different formulations towards age-stable universal colorant dispersion involving economic grade carbon blacks and soya oil ethoxylate.

Experimental batches STD BTH-1 BTH-2 BTH-3 BTH-4 BTH-5
Batch Size 500 ml 500ml
Pigment Specialty carbon black Economic Carbon Black
Surfactant in recipe Soya oil ethoxylate Soya oil ethoxylate
Additional additive / Surfactants - - 2% blend of non-ionic and anionic surface active components 2% anionic, polymeric dispersing agent 2% High molecular weight non-ionic dispersing agent 2% Block copolymer with pigment affinic groups
Drop in T.S Passes Failed Failed Failed Failed Failed
5.58% 25.57% 10.05% 14.04% 10.38% 9.32%

While all the formulation with different additives and soya oil ethoxylate of Table-2 were failed toincorporate economic carbon black effectively,surprisingly – the formulation containing Zinc Octoate (1.5%)andalkyl ethoxylated surfactant including Castor oil ethoxylatewas successfulto arrest drop in T.S. criteria as per Table 3 below. Said castor oil ethoxylate, preferably is castor oil based ethoxylated surfactant wherein castor oil is condensed with preferably 36 moles of ethylene oxide per mole of castor oil and is having HLB value in the range of 12-14. Experimentationswith organometallic compound preferably Zinc Octoate showed robustness in recipe at 1.5% dosage. Thus keeping Zinc Octoate quantity constant, different levels of castor oil ethoxylate were tried and 1.5: 13.3 was found to be the best.

The successful universal carbon blackbased pigment dispersion involving economicgrade carbon blacks as above was incorporated into water based paint and enamel paint (both preferably alkyd based)formulation and were subjected at 55°C for one months to test for extended age stability and tinting strength. The characteristics of the said formulationsinvolving economic grade and similar formulation involving specialty grade carbon black were evaluated – both freshly prepared as well as post stability test and are presented in Table-3.

Table 3: Comparatives for Specialty carbon black based paint formulation vs. Economic carbon black based paint formulation (freshly prepared and post stability test)
SPECIALTY CARBON BLACK ECONOMIC CARBON BLACK
LAB PEL STD Recipe – BTH size 10 Ltr LAB PEL Experimental batch - Batch Size 10 Ltr
Surfactant package Soya oil ethoxylate Castor oil ethoxylate + Zinc Octoate
% TS in Water based paint 105.02% (Vs. Common Master sample) 102.24% (Vs. LAB PEL STD)
% TS in Enamel Paint 109.89% (Vs. Common Master sample) 101.65% (Vs. LAB PEL STD)
Dispersion in Water based paint Passes Passes
Dispersion in Enamel paint Passes Passes
1 Month acc. Stability
Viscosity on Stormer (Initial / after stability) 79.3 / 81.2 69.5 / 67.5
pH on pH meter (Initial / after stability) 7.99 / 7.31 7.54 / 7.30
% TS in Water based paint 101.63% (Vs. Self) 100.92% (Vs. LAB PEL STD)
% TS in Enamel Paint 87.54% (Vs. Self) 100.63% (Vs. LAB PEL STD)

It is evidentfrom Table3that freshly prepared water based paint and enamel based paint involving specialty carbon black and economic carbon black display similar characteristics. After one month of accelerated stability test the viscosity of the specialty carbon formulation increases marginally whereas the same decreases marginally for economic grade carbon black formulation. The %TS remains the same before and after accelerated stability test for water based paint formulation for both the cases indicating there is no drop in tinting strength. However, for enamel paint %TS is reduced by ~15% in case of specialty grade carbon formulation after accelerated stability test whereas the same does not change for enamel paint involving theeconomic grade carbon black dispersion/ formulation in accordance to the present invention.
The universal pigment dispersion of the present inventionincorporating selective ethoxylated surfactant along with Zinc based organometallic compound as an additiveenables synergistic improvement in storage stability of alkyd based paints (water based and enamel) containing economic grade carbon black and arreststhe drop in tinting strength, especially foralkyd based enamel paint. The same formulation having special co-action can be equally used for engineered/specialty carbon blacks that retains the tinting strength in said paints.Thus the robust pigment dispersion formulation involving Zn octoate and ethoxylated surfactant of hydroxy fatty acidadditive is adapted for universal pigment dispersion formulationfor incorporation of pigments in paints including economic grade carbon black and specialty carbon black thereby opening up avenues for production of existing product with lower cost and new quality product following cheaper route.
,CLAIMS:We Claim:
1. A pigment dispersionformulation comprising
(a)11.5 to 14.5wt.% ethoxylated surfactant of hydroxy fatty acid ethoxylate having HLB values in the range of 12-14;
(b)1to 2wt. %a transition metal based organometallic compound including Zinc based organometallic compound.

2. The pigment dispersion formulation as claimed in claim 1 adapted as universal pigment dispersion formulation for dispersing pigments including specialty carbon black, economic grade carbon black or combinations thereof in both water based paint and enamel based paint conferring tinting strength shelf life to said paints particularly solvent based alkyd paints.

3. The pigment dispersion formulation as claimed in claims 1 or 2 wherein said formulation allows incorporation of 7.3to 9wt.%pigment preferably carbon blackincluding specialty carbon black or economic grade carbon blackor combinations thereof in said pigment dispersion formulation or paint formulations when the ratio of said (a): (b)is in the range of 8to12allowing shelf life of tinting strength free of any drop in tinting strength in said paints even after accelerated stability tests.

4. The pigment dispersion formulation as claimed in claims 1-3 wherein
said hydroxy fatty acid ethoxylate having HLB value in the range of 12-14 includes castor oil ethoxylate,soya oil ethoxylate, groundnut oil ethoxylate either individually or in combination;
saidZn based organometallic compound is salt of carboxylic acid having 2-14 carbon atoms including Zn octoate.

5. The pigment dispersion formulation as claimed in claims 1-4 wherein
said hydroxy fatty acid ethoxylate with desired HLB value is castor oil ethoxylate having approximately 36 moles of ethylene oxide per mole of castor oil for attaining the desired HLB value; and
saidcarbon black is economic grade carbon black and includes engineered carbon black preferablyeconomic grade carbon blacks including Carbon Black ISAF N220, Carbon Black HAF N330, Carbon Black FEF N550 and Carbon Black HFM N660.

6. The pigment dispersion formulation as claimed in claims 1-5 that is compatible with other surfactants employable in said dispersion formulation and paints enabling robust formulation of existing colorantsthat is cost effective being free of said requirement of specialized carbon blacks.

7. The pigment dispersion formulation as claimed in claims 1-6 allowing incorporation of economic grade carbon black in said dispersion formulation or paints that displays similar characteristics when incorporated into freshly prepared water based paint and enamel based paint in respect of specialty carbon black whereas %TS remains the same before and after accelerated stability test for water based paint formulation for both the casesand % TS remains the same compared to ~15% reduction of the same for enamel paint involving specialty grade carbon formulation.

8. A process of manufacturing pigment dispersion formulation as claimed in claims 1-7 comprising the steps of
Providing (a) 11.5 to 14.5 wt.% ethoxylated surfactant of hydroxy fatty acid ethoxylate having HLB values in the range of 12-14;(b) 1 to 2 wt. % a transition metal based organometallic compound including Zinc based organometallic compound;
Premixing, milling and thinningwherein addition of organometallic compound is done in thinning stage to obtain therefromsaid pigment dispersion formulation.

9. The process of manufacturing pigment dispersion formulation as claimed in claim 8wherein when the organometallic compound is added at thinning stage the ratio of surfactant to organometallic compound is maintained at preferably 12.8:1.5.

Dated this the 30th day of July, 2022 Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
IN/PA-199