Patent Description:
Rheology modifiers are known to control a viscosity of a formulation over a wide shear rate range. In particular, the rheology modifier provides a large thickening effect at low cost and can be used for a wide range of applications including coatings, paints, lacquers, etc. In order to obtain an efficient thickening effect, specifically with the use of water-soluble rheology modifier, it is desirable to design the rheology modifier which has a suitable molecular weight and water compatibility. Most rheology modifiers are produced from petrochemical feedstocks, and there is a demand for environmentally friendly rheology modifiers.

A rosin is a natural, abundant, cheap, and non-toxic raw material which can be easily modified to obtain a number of useful products. Desired reactive functional groups can be introduced into the rosin to improve many thermal, physical, mechanical, and functional properties of final materials. A rosin-based rheology modifier can be obtained by incorporating suitable functional groups into the rosin. The performance of a composition for example, waterborne paints can be improved through the addition of known rheological modifiers. Some of the rheology modifiers such as inorganic clays and high molecular weight polymers improve the viscosity during application but fails at leveling of the paint which results in unsightly brush and roller marks after the paint dries. An associative rheology modifier having a low molecular weight and a desired water solubility, improves the overall performance of the composition.

<CIT> discloses a composition comprising at least one silicone modified polymer or at least one isocyanate-terminated polybutadiene prepolymer comprising polybutadiene and isocyanate, and at least one coated alkaline-earth metal filler provided with a coating composition comprising at least one coating compound selected from the group consisting of rosin acids, organic sulfonic acids; alkylsulfates; the esters, the salts or mixtures thereof optionally at least one additive, and optionally at least one catalyst.

<CIT> relates to a paint containing a liquid light stabilizer composed of a liquid ultraviolet absorber and a liquid sterically hindered amine-based light stabilizer.

<CIT> describes an oligoester composition which is a reaction product of a reactant mixture comprising: one or more rosins, at least <NUM>% by weight of one or more monocarboxylic acids and one or more polyhydric alcohols.

Therefore, there is a need for a rheology modifier that can provide better shear thinning effect when added to the composition. Particularly, high shear thinning effect at low shear rates and said shear thinning effect is unaffected by other additives added to the composition.

The present invention relates to an associative rheology modifier according to claim <NUM>. More specifically, the associative rheology modifier is obtainable by a process comprising reacting a rosin acid with a polyether at a mole ratio of the rosin acid to the polyether of > <NUM>:<NUM>, at a temperature from <NUM> - <NUM> and in the presence of an acid catalyst. The polyether has a molecular weight of <NUM> - <NUM>,<NUM>/mol and the rheology modifier precursor has a water solubility of > <NUM> wt. % concentration at a temperature of <NUM>. The rheology modifier precursor is coupled with a coupling agent in an amount of <NUM> - <NUM> wt. %, based on total weight of the rheology modifier precursor, wherein the coupling agent is reactive to carbon-carbon double bonds in the rheology modifier precursor and is selected from sulfur-based agents, peroxide-based agents, acrylate-based agents, tellurium, selenium, polysulfide polymers, metallic oxides and di-isocyanates. The associative rheology modifier has a molecular weight (Mw) from <NUM>,<NUM> - <NUM>,<NUM>/mol, a water solubility of > <NUM> wt. % concentration at a temperature of <NUM>; and an apparent viscosity of <NUM>,<NUM>- <NUM>,<NUM> cP at a shear rate from <NUM> - <NUM>,<NUM>-<NUM> and an apparent viscosity of <NUM>,<NUM>-<NUM> cP at a shear rate from <NUM>,<NUM> - <NUM>,<NUM>-<NUM>, at a concentration of <NUM> wt. % in water and at a temperature of <NUM>.

Preferably, the polyether is selected from the group of polyether glycols, polyetheramine (i.e., Jeffamine), and mixtures thereof, and said polyether has at least one functional group selected from a hydroxyl group and an amine group.

Preferably, the rosin acid is reacted with a polyethylene glycol to obtain a polyethylene glycol end-capped rosin with an ester linkage.

Preferably, the rosin acid is reacted with a polyetheramine (i.e., Jeffamine), to obtain a polyetheramine end-capped rosin with an amide linkage.

The following terms used in the specification have the following meanings:.

"Rheology modifier" or viscosity modifier refers to a type of additive added in a formulation to achieve desired rheological characteristics for the application. Apart from getting desired viscosity, these additives also help in controlling shelf stability of the formulation, ease of application, open time / wet edge and sagging. "Open time" refers to
the period after application when a coating surface is sufficiently wet to allow flow, release of solvents and air, and touching up without leaving marks. Wet edge refers to distinct boundaries where wet and dry layers had overlapped producing lines of color density or gloss difference in coatings.

"Rosin acid" refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. In embodiments, the rosin acids have the same basic skeleton as three fused rings having the empirical formula C<NUM>H<NUM>COOH.

"Associative rheology modifier" refers to rheology modifiers that rely on non-specific interactions between the end-groups of a rheology modifier molecules and the surrounding formulation (as well as with themselves).

"Molecular weight" or Mw refers to the polystyrene equivalent molecular weight in g/mol of a polymer block or a block copolymer. Mw can be measured with gel permeation chromatography (GPC) using polystyrene calibration standards, such as is done according to ASTM <NUM>-<NUM>. The GPC detector can be an ultraviolet or refractive index detector or a combination thereof. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. Mw of polymers measured using GPC so calibrated are polystyrene equivalent molecular weights or apparent molecular weights. Mw expressed herein is measured at the peak of the GPC trace and are commonly referred to as polystyrene equivalent "peak molecular weights," designated as Mp.

The present disclosure is directed to an associative rheology modifier obtained by coupling of a rheology modifier precursor with a coupling agent. The rheology modifier precursor is formed by reacting a rosin acid with a polyether. The associative rheology modifier shows a high shear thinning effect at low shear rate.

Rosin acid: The rosin acid is selected from those natural rosin-based acids, such as those obtained from residues of distillation of natural oils. The rosin acid and its derivatives can be known derivatives of a carbonyl-containing compound known in Organic Chemistry Textbooks, such as "<NPL>.

In embodiments, rosin acids include those that are isolated from black liquor skimming, crude tall oil, tall oil pitch, and distilled tall oil. In addition, rosin acids can be those found in tall oil rosin, gum rosin and wood rosin. These naturally occurring rosins can be suitably mixtures and/or isomers of monocarboxylic tricyclic rosin acids usually containing about <NUM> carbon atoms. The tricyclic rosin acids differ in the position of the double bonds. The rosin acid can be at least one of levopimaric acid, neoabietic acid, palustric acid, abietic acid, dehydroabietic acid, secodehydroabietic acid, tetrahydroabietic acid, dihydroabietic acid, parinaric acid, palustric acid, and isopimaric acid, or mixtures, isomers, and/or derivatives thereof. The rosins derived from natural sources also include rosins, e.g., rosin mixtures, modified notably by polymerization, isomerization, disproportionation, and hydrogenation.

In embodiments, the rosin acid contains at least one saturated or unsaturated, monocarboxylic aliphatic hydrocarbon or derivative thereof having a linear, branched, and/or cyclic chain, a dimer thereof, a trimer thereof, or mixtures thereof. The saturated or unsaturated, monocarboxylic aliphatic hydrocarbon has number of carbon atoms, for example, from <NUM> to <NUM> carbon atoms, or <NUM> to <NUM>, or <NUM> to <NUM>, or > <NUM>, or < <NUM>.

In embodiments, the rosin acid can be subjected to one or more purification steps (e.g., distillation under reduced pressure, extraction, and/or crystallization), if desired, prior to its use as a rosin acid. Hydrogenated rosins and partially hydrogenated rosins can also be used as a rosin acid source.

In embodiments, the rosin acid is reacted with an adduction agent to obtain a rosin acid adduct through a Diels-Alder reaction. The adduction agent is selected from the group consisting of unsaturated acids, anhydrides, and mixtures thereof. Example of adduction agent includes maleic anhydride, maleic acid, fumaric acid, and the like. The Diels-Alder reaction involves the reaction of an α, β-unsaturated carbonyl compound of the adduction agent with a conjugated double bond of the rosin acid. In embodiments, the rosin acid adduct is reacted with the polyether to form a rheology modifier precursor.

Polyether: The rosin acid is reacted with at least one polyether to obtain the rheology modifier precursor. In embodiments, the polyether has at least one functional group selected from a hydroxyl group and an amine group positioned at any place on the polyether polymer chain. In embodiments, the polyether has the functional group on at least one terminal end of the polyether polymer chain.

In embodiments, the polyether is selected from the group of poly glycols, polyetheramine (i.e., Jeffamine), and mixtures thereof. Non-limiting examples of poly glycols include a polyethylene glycol, a polypropylene glycol, a polybutylene glycol, a polytetrahydrofuran, a polytetramethylene glycol, a polytetramethylene ether glycol, and mixtures thereof.

In embodiments, the polyether is selected from polyetheramines having a polyether backbone typically based on ethylene oxide or propylene oxide units. For example, monoamines, diamines and triamines can be attached to the polyether polymer chain at one or more terminal ends, such as amine-terminated polyethers.

In accordance with the present invention, the polyether has a molecular weight (Mw) of <NUM> - <NUM>,<NUM>/mol and preferably of <NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or ≤ <NUM>,<NUM>/mol.

In embodiments, the polyether is a polyethylene glycol (PEG), having a molecular weight (Mw) of <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or ≤ <NUM>,<NUM>/mol.

In embodiments, the polyether is a polyetheramine having a molecular weight (Mw) of <NUM> - <NUM>,<NUM>/mol, or <NUM> - <NUM>,<NUM>/mol, or <NUM> - <NUM>,<NUM>/mol, or <NUM> - <NUM>,<NUM>/mol, or ≤ <NUM>,<NUM>/mol.

Rheology Modifier Precursor: To obtain the rheology modifier precursor, the rosin acid is reacted with the polyether at a mole ratio of > <NUM>:<NUM>, such as <NUM>:<NUM> - <NUM>:<NUM>, or <NUM>:<NUM> - <NUM>:<NUM>, or <NUM>:<NUM> - <NUM>:<NUM>. In embodiments, the rosin acid is present in an amount of <NUM> - <NUM> mol. %, or > <NUM> mol. %, or up to <NUM> mol. %, or up to <NUM> mol. %, excess compared to the amount of the polyether, based on the total mol.

In embodiments, with the polyether being a PEG, the reaction results in a PEG-end-capped rosin with an ester linkage. The PEG end-capped rosin is obtained by having a ratio of an acid number of rosin acid to a hydroxyl number of PEG of <NUM>:<NUM>. For embodiments with polyether being a polyetheramine end-capped rosin is obtained with an amide linkage, with a mole ratio of an acid number of rosin acid to an amine number of the polyetheramine is <NUM>:<NUM>.

In embodiments, the rheology modifier precursor is obtained by reacting a rosin dimer with at least one polyether at a mole ratio of the rosin dimer to the polyether of > <NUM>:<NUM>, such as <NUM>: <NUM> - <NUM>:<NUM> or > <NUM>:<NUM>.

In embodiments, the rosin acid is reacted with the polyether in an acidic condition, at atmospheric pressure and under non-active nitrogen containing gas environment. Examples of catalysts for promoting the reaction between the rosin acid and the polyether include Brønsted acids and Lewis acids. Examples of Brønsted acid include but are not limited to mineral acids, organic acids, heteropolyacids, zeolites, acid clays, sulfated zirconia, and mixtures thereof. Examples of catalysts forming the precursor include but are not limited to hydrochloric acid, nitric acid, phosphoric acid, hypophosphorous acid, sulfuric acid, boric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, toluenesulfonic acid, formic acid, acetic acid, oxalic acid, trifluoroacetic acid, calcium-bis(((<NUM>,<NUM>-bis(<NUM>,<NUM>-dimethylethyl)-<NUM>-hydroxyphenyl)methyl)-ethylphosphonate and the like.

In embodiments, the water solubility of the rheology modifier precursor is dependent on the molecular weight (Mw) of the polyether used, e.g., a PEG, to react with the rosin acid. In embodiments with PEG having a Mw of <NUM>,<NUM>/mol, the water solubility of a rheology modifier precursor is higher than the water solubility of a precursor made with a lower Mw PEG, e.g., < <NUM>,<NUM>/mol. In examples with PEG having a low Mw, e.g., < <NUM>/mol, the rheology modifier precursor does not have sufficient water solubility.

In embodiments, the rheology modifier precursor has a molecular weight (Mw) of <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or <NUM>,<NUM> - <NUM>,<NUM>/mol, or > <NUM>,<NUM>/mol, or < <NUM>,<NUM>/mol.

In embodiments, the rheology modifier precursor has a polydispersity index (PI) ranging from <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or > <NUM>, or < <NUM>.

In embodiments, the rheology modifier precursor has a viscosity of <NUM>,<NUM> - <NUM>,<NUM> cP, or <NUM>,<NUM> - <NUM>,<NUM> cP, or <NUM>,<NUM> - <NUM>,<NUM>, or <NUM>,<NUM> - <NUM>,<NUM> cP, or <NUM>,<NUM> - <NUM>,<NUM> cP, or < <NUM>,<NUM> cP, at 25wt. % concentration of the precursor in water measured at a temperature of <NUM>.

In embodiments, the rheology modifier precursor has an acid value of <NUM> - <NUM> KOH/g, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or < <NUM>, or < <NUM> KOH/g.

In embodiments, the rheology modifier precursor has a Hunter color value of <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or < <NUM>.

In accordance with the present invention, the rheology modifier precursor has a water solubility of > <NUM> wt. % concentration at a temperature of <NUM>, preferably of <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or > <NUM> wt. %, or ≤ <NUM> wt. %, or ≤ <NUM> wt. %, all at <NUM>, based on the total weight of the rheology modifier precursor and water.

Associative Rheology Modifier: The rheology modifier precursor has carbon-carbon double bonds that are reactive to a coupling agent, which allows formation of an associative rheology modifier. As the coupling agent, free radical initiators are especially desirable. They generate radicals at elevated temperature or under the triggering effect of UV or other energy sources. In accordance with the present invention, the coupling agent is selected from sulfur-based agents, peroxide-based agents, acrylate-based agents, tellurium, selenium, polysulfide polymers, metallic oxides, and di-isocyanates. Non-limiting examples of sulfur-based coupling agents include S<NUM>Cl<NUM>, elemental sulfur, and sulfur donor compounds that liberate sulfur under the coupling conditions. Some examples of sulfur donor compounds include tetramethyl thiuram disulfide, <NUM>,<NUM>'-dithiodimorpholine, dipentamethylene thiuram tetrasulfide, and thiocarbonyl sulfenamide, dibenzothiazole, N-cyclohexyl-<NUM>-benzothiazole, zinc dimethyl dithiocarbamate, thiourea, xanthates, and thiophosphates.

In embodiments, the coupling agent is an acrylate-based coupling agent, selected from multifunctional acrylates having > <NUM> acrylate groups, e.g., trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, <NUM>,<NUM>-bishexanedioldiacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, and the like.

Other coupling agents include divinylbenzene, <NUM>,<NUM>-diisopropenylbenzene, trimethylallyl isocyanurate, triallyl isocyanurate, <NUM>,<NUM>,<NUM>-triazine-<NUM>,<NUM>,<NUM>(<NUM>,<NUM>,SH)-trithione, pentaerythritol tetra(<NUM>-mercaptopropionate), tris[<NUM>-(<NUM>-mercaptopropionyloxy)ethyl] isocyanurate, <NUM>,<NUM>-ethanedithiol, <NUM>,<NUM>,<NUM>-triallyloxy-<NUM>,<NUM>,<NUM>-triazine, N,N-<NUM>,<NUM>-phenylenediamaleimide, and the like.

In embodiments, enough coupling agent is used for the rheology modifier precursor to be effectively coupled. If the amount of coupling agent is low, the associative rheology modifier may not have desired properties and an undesired gel formation occurs in case of use of higher amount of the coupling agent.

In accordance with the present invention, the coupling agent is used in an amount from <NUM> - <NUM> wt. %, and preferably in an amount of <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, based on the total weight of the rheology modifier precursor.

Preparation of Associative Rheology Modifier: The associative rheology modifier is prepared in accordance with the present invention by mixing the rheology modifier precursor and the coupling agent, at a temperature of <NUM> - <NUM>, preferably <NUM> - <NUM> for <NUM> to <NUM> minutes to provide the associative rheology modifier.

In embodiments, a radical inhibitor is added into the coupling reaction system to prevent the coupling agent from homopolymerization. The radical inhibitors are phenol, thio-based, amine-based, or quinone-based, e.g., p-phenylenediamines, hydroxylamines like diethyl hydroxylamine, phenothiazine <NUM>-tert-butyl catechol, <NUM>-methoxyphenol or tetrahydroquinone or butylated hydroxytoluene and mixtures thereof. in embodiments, the radical inhibitor is added into the coupling reaction in an amount of <NUM> - <NUM> ppm, based on the total weight of the coupling agent.

Coupling efficiency depends on a number of factors such as the amount of the coupling agent, temperatures and other physical conditions used. The coupling efficiency can vary, for example, from > <NUM>%, or > <NUM>%, or > <NUM>%, or > <NUM>%, or > <NUM>%.

Properties of Associative Rheology Modifier: In accordance with the present invention, the associative rheology modifier has an apparent viscosity of <NUM>,<NUM> - <NUM>,<NUM> cP at a low shear rate from <NUM>,<NUM> - <NUM>,<NUM>-<NUM> and an apparent viscosity of <NUM>,<NUM>-<NUM> cP at a high shear rate from <NUM>,<NUM> - <NUM>,<NUM>-<NUM>.

In accordance with the present invention, the associative rheology modifier has a water solubility of > <NUM> wt. % concentration at a temperature of <NUM>, preferably of <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or <NUM> - <NUM> wt. %, or > <NUM> wt. %, or ≤ <NUM> wt. %, or ≤ <NUM> wt. %, based on the total weight of the associative rheology modifier and water.

In accordance with the present invention, the associative rheology modifier has a linear or a branched structure, with a molecular weight of <NUM>,<NUM> - <NUM>,<NUM>/mol, such as of <NUM>,<NUM> - <NUM>,<NUM>/mol, or of <NUM>,<NUM> - <NUM>,<NUM>/mol.

In embodiments, the associative rheology modifier has density of > <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or <NUM> - <NUM>, or < <NUM>.

Applications: The associative rheology modifier can be supplied as a pourable and pumpable liquid for a number of applications, including but is not limited to oil field chemicals, coatings, paint applications, cleaning agents, cosmetics, aqueous pigment pastes, automotive finishes, industrial coatings, printing inks, lubricating greases, plaster paints and wall paints, textile coatings, filler dispersions, adhesives, detergents, wax dispersions, polishes, auxiliaries for tertiary mineral oil production, food industries, paper industries etc..

In applications, the associative rheology modifier functions to modify the rheological behavior of end-use compositions such that, on the one hand, in a state of low shear, the composition has a high viscosity. Therefore, in use when the composition is coated or is applied to a vertical surface, there is minimal running (curtaining). On the other hand, the mechanical stress in a state of high shear, lowers the viscosity (shear-thinning). In use, the composition becomes highly mobile, and can be conveyed through a narrow nozzle as applied by spray gun. The associative rheology modifier improves sag resistance by a rapid but controlled viscosity increase after application, also reliably prevent sedimentation of additives such as pigments during transport and storage of the composition.

In embodiments of paint applications, e.g., a waterborne paint composition, the paint composition comprises <NUM> - <NUM> wt. % of water, <NUM> - <NUM> wt. % of at least a pigment, <NUM> - <NUM> wt. % of at least a binder, <NUM> - <NUM> wt. % of the associative rheology modifier, and <NUM> - <NUM> wt. % of at least an additive, based on the total weight % of the waterborne paint composition. The paint can be prepared by dispersing water, pigments, and other additives in a grinder. A binder based on styrene-acrylic copolymer is added, then followed by the associative rheology modifier.

In embodiments, a water-borne paint composition prepared with the associative rheology modifier has a low shear viscosity (LSV) of <NUM> - <NUM>-<NUM>, medium shear viscosity (MSV) <NUM> - <NUM>-<NUM>, and high shear viscosity (HSV) <NUM><NUM> - <NUM><NUM> s-<NUM>. The LSV correlated to settling, sagging, and leveling of the waterborne paint composition. The MSV correlates to brush loading and rolling, whereas HSV correlates to spraying of the waterborne paint composition.

The thinning effect of the waterborne paint composition is measured by Rheometer TA, DHR-<NUM>, cone <NUM>, <NUM> rad at <NUM> shear ramp at shear rate of <NUM> - <NUM>-<NUM>. The stability of the waterborne paint composition can be confirmed by measuring the viscosity of the composition at various intervals, for example, measuring the viscosity immediately after preparation of the composition at <NUM>, after <NUM> days at <NUM>, after <NUM> days at <NUM>, after <NUM> days at <NUM>, after <NUM> days at <NUM>, after <NUM> days at <NUM>.

Examples: The following illustrative examples are intended to be non-limiting.

Materials: The following materials are used.

The PEG materials used in examples have different molecular weights, for example, PEG1 - <NUM>,<NUM>/mol, PEG2 - <NUM>,<NUM>/mol, PEG3 - <NUM>,<NUM>/mol, and PEG4 - <NUM>,<NUM>/mol.

SYLVAROS™ HYR: A tall oil resin with acid number <NUM> KOH/g and sulfur content <NUM> ppm commercially available from Kraton Corp.

Synthesis of rheology modifier precursors.

Example <NUM>: About <NUM> of a polyethylene glycol (PEG1) was charged in a round bottom flask. The round bottom flask was heated to a temperature of <NUM> under mechanical stirring at <NUM> rpm and under nitrogen flow to obtain a molten PEG. Into the molten PEG, about <NUM> of SYLVAROS™ HYR and about <NUM> of hypophosphorous acid <NUM>% aqueous solution were added slowly under continuous stirring at <NUM> rpm. The reaction mixture was then heated from <NUM> - <NUM> over a period of an hour. The acid value of the reaction content was monitored through the titration. The reaction was continued at <NUM> to obtain the acid value of ≤ <NUM> KOH/g of the reaction content. The reaction content was cooled down to a room temperature to obtain a rheology modifier precursor with an acid value of <NUM>, a Gardner color of <NUM>, a viscosity of <NUM>,<NUM> cP, a Mw of <NUM>,<NUM>/mol and a PI of <NUM>.

Example <NUM>: Example <NUM> was repeated, except that <NUM> wt. % of additional catalyst dibutyltin oxide (DBTO) with about <NUM> of hypophophorous acid <NUM>% (aqueous solution), about <NUM>,<NUM> of PEG1, and about <NUM> of SYLVAROS™ HYR were used in the synthesis of the precursor, giving a rheology modifier precursor with an acid value of <NUM>, a Gardner color value of <NUM>, a viscosity of <NUM>,<NUM> cP, a Mw of <NUM>,<NUM>/mol and a PI of <NUM>.

Example <NUM>: Example <NUM> was repeated, except that <NUM> of <NUM>% hypophophorous acid (aqueous solution), ~ <NUM>,<NUM> of PEG2, and ~ <NUM> of SYLVAROS™ HYR were used, giving a rheology modifier precursor with an acid value of <NUM>, a Gardner color value of <NUM>, a viscosity of <NUM>,<NUM> cP, a Mw of <NUM>/mol and a PI of <NUM>.

Example <NUM>: Example <NUM> was repeated, except that about <NUM> of <NUM>% hypophophorous acid (aqueous solution), ~ <NUM>,<NUM> of PEG3, and ~ <NUM> of SYLVAROS™ HYR were used, giving a rheology modifier precursor with an acid value of <NUM>, a Gardner color value of <NUM>, a viscosity of <NUM>,<NUM> cP, a Mw of <NUM>,<NUM>/mol and a PI of <NUM>.

Synthesis of associative rheology modifiers.

Example <NUM>: In a reaction vessel, about <NUM> of the rheology modifier precursor obtained in Example <NUM> was mixed with about <NUM> of deionized water under stirring at <NUM> rpm, at room temperature (<NUM>) and under nitrogen atmosphere. About <NUM> of pentaerythritol tetra(<NUM>-mercaptopropionate) was added dropwise over <NUM>. into the reaction mixture. The color of the reaction mixture was changed from amber brown to a pale yellow with increased viscosity. About <NUM> of <NUM> wt. % of sodium persulfate stock solution in deionized water was added dropwise. A temperature drop was observed from room temperature (<NUM>) to <NUM>. The temperature was then increased up to <NUM> over <NUM>. Increase in viscosity was observed in the reaction vessel and to ensure complete reaction, heating was increased to <NUM> for refluxing. After refluxing for <NUM>. the reaction content was transferred into the glass jar to collect an associative rheology modifier with a Gardner color value of <NUM> and a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that there was no refluxing and the reaction was completed at a temperature of <NUM>, for an associative rheology modifier with Gardner color of <NUM> and a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that <NUM> wt. % of radical initiator as potassium persulfate was used instead of <NUM> of sodium persulfate. An associative rheology modifier with Gardner color of <NUM> and a viscosity of <NUM>,<NUM> cP.

Example <NUM>: In a reaction vessel, about <NUM> of the rheology modifier precursor obtained in Example <NUM> was mixed with about <NUM> of N,N'-<NUM>,<NUM>-phenylenedimaleimide (PMD) and the mixture was heated at <NUM> with continuous stirring at <NUM> rpm. The stirring speed was increased to <NUM>,<NUM> rpm and the temperature for heating was augmented to <NUM>. The reaction was continued at <NUM> for <NUM>. resulting in change in color from cloudy light brown-yellow to a clear yellow-orange with increase in viscosity. The reaction mixture was then cooled down to <NUM> to collect an associative rheology modifier with a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that about <NUM> of radical initiator <NUM>-<NUM>-dimethyl-<NUM>-<NUM>-di-tert-butylperoxy-hexane (DHBP) was added at <NUM> and amount of the rheology modifier precursor was about <NUM>. An associative rheology modifier has a viscosity of <NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that ~ <NUM> of the rheology modifier precursor obtained in Example <NUM> was mixed with about <NUM> of PMD, which was <NUM> wt. % of the coupling agent. An associative rheology modifier has a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that <NUM> of the rheology modifier precursor obtained in Example <NUM> was mixed with about <NUM> of PMD, which was <NUM> wt. % of the coupling agent. An associative rheology modifier has a viscosity of <NUM>,<NUM> cP.

Example <NUM>: In a reaction vessel, about <NUM> of the rheology modifier precursor obtained in Example <NUM> was mixed with <NUM> of trimethylolpropane trimethacryate (TMPTAM) and <NUM> of DHBP. Once molten, <NUM> (<NUM> ppm) of inhibitor phenothiazine was added slowly under low nitrogen protection. The reaction mixture was heated to <NUM> temperature with continuous stirring at <NUM> rpm. The viscosity of the reaction mixture was started to increase and then the temperature of the reaction mixture was increased to <NUM>. After <NUM>. , the color of the reaction mixture was changed from light yellow to clear pale yellow. The reaction was cooled down to room temperature to collect an associative rheology modifier with a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that about <NUM> of trimethylolpropane triacryate (TMPTA) coupling agent was used and the reaction was conducted in the absence of DHBP radical initiator, with <NUM> ppm of phenothiazine. An associative rheology modifier has a viscosity of <NUM>,<NUM> cP.

The TMPTA coupling agent for coupling the rheology modifier precursor shows better viscosity in comparison with the TMPTAM coupling agent.

Example <NUM>: Example <NUM> was repeated, except that the rheology modifier precursor was used obtained from Example <NUM> and about <NUM> wt. % (<NUM>) of TMPTA as the coupling agent was used. An associative rheology modifier has a viscosity of <NUM>,<NUM> cP.

Example <NUM>: In a reaction vessel, about <NUM> of the rheology modifier precursor was used obtained from Example <NUM> and heated to a temperature of <NUM> with stirring at <NUM> rpm. After complete melting of the associative rheology modifier, about <NUM> of trimethylolpropane triacryate (TMPTA) and <NUM> of DHBP were slowly added to the reaction vessel under continuous stirring. Once molten <NUM>,<NUM> ppm of phenothiazine was added slowly under low nitrogen protection. The temperature of the reaction mixture was increased from <NUM> to about <NUM> over a period of an hour. The reaction was continued for <NUM>. at <NUM> temperature. The reaction was cooled down to a room temperature to collect an associative rheology modifier with a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that about <NUM> wt. % (<NUM>) of TMPTA as the coupling agent was used. An associative rheology modifier has a viscosity of <NUM>,<NUM> cP.

Example <NUM>: Example <NUM> was repeated, except that about <NUM> wt. % (<NUM>) of TMPTA as the coupling agent was used. An associative rheology modifier was gelled.

The associative rheology modifier obtained in Example <NUM> was slightly gelled due to the higher amount of the coupling agent (<NUM> wt. Whereas the sample obtained from Example <NUM> was completely gelled owing to higher amount of the coupling agent, which was about <NUM> wt.

Process of preparation of waterborne paint composition.

Example <NUM>: About <NUM> of water, <NUM> of TiO<NUM>, and desired number of additives were mixed in a pearl mill NETZSCH at <NUM>,<NUM> - <NUM>,<NUM> RPM for <NUM> - <NUM> minutes. To this mixture, about <NUM> of styrene-acrylic copolymer-based binder was added followed by dropwise addition of <NUM> of the associative rheology modifier. The addition of the associative rheology modifier is conducted by using dissolver IKA-WERKE at <NUM> - <NUM>,<NUM> RPM at room temperature (<NUM>). The waterborne paint composition was obtained after homogenous mixing of above components.

Claim 1:
An associative rheology modifier obtainable by a process comprising:
reacting a rosin acid with a polyether at a mole ratio of the rosin acid to the polyether of > <NUM>:<NUM>, at a temperature from <NUM> - <NUM> and in the presence of an acid catalyst to form a rheology modifier precursor,
wherein the polyether has a molecular weight (Mw) of <NUM> - <NUM>,<NUM>/mol; and
the rheology modifier precursor has a water solubility of > <NUM> wt.% concentration at a temperature of <NUM>;
coupling the rheology modifier precursor with a coupling agent in an amount of <NUM> - <NUM> wt.%, based on total weight of the rheology modifier precursor, wherein the coupling agent is reactive to carbon-carbon double bonds in the rheology modifier precursor and is selected from sulfur-based agents, peroxide-based agents, acrylate-based agents, tellurium, selenium, polysulfide polymers, metallic oxides and di-isocyanates;
wherein the associative rheology modifier has
a molecular weight (Mw) of <NUM>,<NUM> - <NUM>,<NUM>/mol; and
a water solubility of > <NUM> wt.% concentration at a temperature of <NUM>; and
an apparent viscosity of <NUM>,<NUM>- <NUM>,<NUM> cP at a shear rate from <NUM>,<NUM> - <NUM>,<NUM>-<NUM> and an apparent viscosity of <NUM>,<NUM>-<NUM> cP at a shear rate from <NUM>,<NUM> - <NUM>,<NUM>-<NUM>, at a concentration of <NUM> wt.% in water and at a temperature of <NUM>.