AQUEOUS COATING COMPOSITIONS

Field

The present invention relates to compositions and aqueous coating compositions, and to methods for improving the freeze/thaw stability of aqueous coating compositions.

Introduction

Manufacturers of paints and coatings are developing new latex binders that do not require the use of volatile solvents and coalescing agents in response to environmental regulations that limit the use of volatile organic compounds (VOC). One of the primary challenges in eliminating solvents from a paint or coating formulation is associated with freeze-thaw stability of the formulation.

Paints and coatings are often subjected to freezing and thawing cycles during storage and shipping due to a lack of temperature control. Under such conditions, the colloidal stability of latex resin particles is compromised, and can result in changes in the consistency of the paint or coating due to drastic changes in formulation viscosity. This can cause the paint or coating to be unusable in many instances.

Solvents such as glycols have been historically used to protect paints and coatings from freeze-thaw stability problems. However, glycol solvents typically have high levels of VOCs.

It would be desirable to have new additives for improving the freeze-thaw stability of paints and other coatings but with reduced levels of VOCs.

Summary

The present invention provides additives for paints and other coatings that can improve the freeze-thaw stability of the paints/coatings. In some embodiments, such additives can provide good coalescence and freeze-thaw protection to the paints/coatings.

In some embodiments, such additives have low to near zero- VOC content.

In one aspect, the present invention provides a method for improving the freeze/thaw stability of an aqueous coating composition comprising an aqueous polymeric dispersion, the method comprising adding the compound of Formula 1 to the aqueous coating composition: (Formula 1) wherein n = 3 to 10. The aqueous coating composition can be a paint or coating, in some embodiments.

In another aspect, the present invention provides an aqueous coating composition, such as a paint, that comprises an aqueous polymeric dispersion and the compound of Formula 1:

(Formula 1) wherein n = 3 to 10 and wherein the coating composition comprises 5 to 10 percent by weight of Formula 1 based on the weight of the polymeric dispersion solids.

In another aspect, the present invention provides a composition that comprises the compound of

(Formula 1) wherein n = 3 to 10; and

(Formula 2) wherein the composition comprises 30 to 70 percent by weight of Formula 1 and 30 to 70 percent by weight of Formula 2

These and other embodiments are described in more detail in the Detailed Description. Detailed Description

As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. The terms "comprises," "includes," and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Thus, for example, an aqueous composition that includes particles of "a" hydrophobic polymer can be interpreted to mean that the composition includes particles of "one or more" hydrophobic polymers.

Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed in that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). For the purposes of the invention, it is to be understood, consistent with what one of ordinary skill in the art would understand, that a numerical range is intended to include and support all possible subranges that are included in that range. For example, the range from 1 to 100 is intended to convey from 1.01 to 100, from 1 to 99.99, from 1.01 to 99.99, from 40 to 60, from 1 to 55, etc. Also herein, the recitations of numerical ranges and/or numerical values, including such recitations in the claims, can be read to include the term "about." In such instances the term "about" refers to numerical ranges and/or numerical values that are substantially the same as those recited herein.

Some embodiments of the present invention relate to methods for improving the freeze/thaw stability of an aqueous coating composition comprising an aqueous polymeric dispersion, such as paint or a coating. In some embodiments, the method comprises adding the compou sition:

(Formula 1) wherein n = 3 to 10. In some embodiments, n = 5 to 10, while n = 6 to 8 in other embodiments and n = 8 in still other embodiments.

In some embodiments, 5 to 10 percent by weight of Formula 1 is added to the aqueous coating composition, based on the weight of the polymeric dispersion solids. 6 to 8 percent by weight of Formula 1 is added to the aqueous coating composition, based on the weight of the polymeric dispersion solids, in some embodiments. In some embodiments, methods of the present invention further comprise adding at least one coalescent to the aqueous coating composition. Such a coalescent, in some emb (Formula 2).

In some embodiments, 2 to 12 percent by weight of Formula 2 is added to the aqueous coating composition, based on the weight of the polymeric dispersion solids. The coalescent, in some embodiments, comprises at least one of propylene glycol phenyl ether, ethylene glycol phenyl ether, dipropylene glycol n-butyl ether, ethylene glycol n-butyl ether benzoate, tripropylene glycol n-butyl ether, 2,2,4-trimethyl-l,3-pentanediol

monoisobutyrate, and triethylene glycol bis-2-ethylhexanoate.

The aqueous polymeric dispersion comprises an acrylic polymer in some embodiments.

In some embodiments, methods of the present invention further comprise adding one or more polyalkoxylates to the aqueous coating composition.

Some embodiments of the present invention relate to aqueous coating compositions, such as paints or other coatings. Aqueous coating compositions, in some embodiments, comprise an aqueous polymeric dispersion and the compound of Formula 1 :

(Formula 1) wherein n = 3 to 10 and wherein the coating composition comprises 5 to 10 percent by weight of Formula 1 based on the weight of the polymeric dispersion solids. In some embodiments, n = 5 to 10, while n = 6 to 8 in other embodiments and n = 8 in still other embodiments. 6 to 8 percent by weight of Formula 1 is added to the aqueous coating composition, based on the weight of the polymeric dispersion solids, in some embodiments.

The aqueous polymeric dispersion comprises an acrylic polymer in some embodiments.

In some embodiments, aqueous coating compositions of the present invention further comprise at least one coalescent. Such a coalescent, in some embodiments, comprises the compound of Formula 2: (Formula 2).

In some embodiments, aqueous coating compositions of the present invention comprise 2 to 12 percent by weight of Formula 2, based on the weight of the polymeric dispersion solids. The coalescent, in some embodiments, comprises at least one of propylene glycol phenyl ether, ethylene glycol phenyl ether, dipropylene glycol n-butyl ether, ethylene glycol n- butyl ether benzoate, tripropylene glycol n-butyl ether, 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, and triethylene glycol bis-2-ethylhexanoate.

In some embodiments, aqueous coating compositions of the present invention further comprise one or more polyalkoxylates.

Some embodiments of the present invention relate to compositions that comprise the compou

(Formula 1) wherein n = 3 to 10; and

the compound of Formula 2: (Formula 2) wherein the composition comprises 30 to 70 percent by weight of Formula 1 and 30 to 70 percent by weight of Formula 2. In some embodiments, n = 5 to 10, while n = 6 to 8 in other embodiments and n = 8 in still other embodiments. Such compositions can be provided as additives to aqueous coating compositions, such as paints or other coatings, in some embodiments.

Compounds of Formula 1 to be used in various embodiments of the present invention can be obtained by reacting alcohols with ethylene oxide. Preferred

polyethoxylated alcohols are prepared by reacting the desired alcohol with ethylene oxide in the presence of a catalyst (e.g., BF3 etherate, dimethyl cyanide, alkali metals such as sodium hydroxide and potassium hydroxide or others) using techniques known to skill in the art.

For example, polyethoxylated 2,6,8-trimethyl-4-nonanol is prepared by reacting 2,6,8- trimethyl-4-nonanol with ethylene oxide in the presence of a catalyst. Any of several synthetic methods known to those skilled in the art can be used to prepare the

aforementioned polyethoxylated 2,6,8-trimethyl-4-nonanol. As the synthesis results in a distribution of polyethoxylated alcohol homologues, the relative amounts of alcohol and ethylene oxide can be selected to obtain the desired distribution of homologues. For example, the ratio of ethylene oxide to alcohol can be selected to provide a distribution of Formula 1 compounds wherein n is predominantly between 3 and 10 and/or wherein the average n value is between 5 and 6. Polyethoxylated alcohols obtained by any of the aforementioned methods can be purified according to methods known to those skilled in the art, such as by low pressure stripping.

The reaction can be carried out in a batch or continuous manner. As noted above, a catalyst can be used to enhance the reaction. It is possible to remove the catalyst from the reaction mixture so that the reaction mixture is substantially free of catalyst, and in one embodiment of the invention, the catalyst is removed from the reaction mixture. For example, catalysts can be removed from the reaction process by neutralization with an appropriate reagent.

One example of a polyethoxylated 2,6,8-trimethyl-4-nonanonl of Formula 3 that can be used in some embodiments is TERGITOL™ TMN 6, which is commercially available from The Dow Chemical Company. TERGITOL™ TMN 6 comprises a blend of polyethoxylated nonanols of Formula 1 having an average of n = 5 - 6.

In one aspect, compounds of Formula 1 can be added to an aqueous coating composition to improve the freeze/thaw stability of the aqueous coating composition according to methods of the present invention. Paint is one example of such an aqueous coating composition.

In one aspect of the present invention, there is provided an aqueous coating composition comprising an aqueous polymeric dispersion and from 5 to 10% by weight, based on the weight of polymeric dispersion solids, of the compound of Formula 1 described herein. In some embodiments, the aqueous coating composition comprises from 6 to 8% by weight, based on the weight of polymeric dispersion solids, of the compound of Formula 1 described herein.

The aqueous coating composition can further comprise one or more coalescents in some embodiments. By "coalescent" is meant an ingredient that facilitates the film formation of an aqueous polymeric dispersion, particularly an aqueous coating composition that includes a dispersion of polymer in an aqueous medium such as, for example, a polymer prepared by emulsion polymerization techniques.

In some embodiments, an aqueous coating composition of the present invention comprises from 2 to 12% by weight, based on the weight of aqueous polymeric dispersion solids, of a coalescent. In some embodiments, an aqueous coating composition of the present invention comprises 6 to 8% by weight, based on the weight of aqueous polymeric dispersion solids, of a coalescent.

Formula 2: (Formula 2).

Compounds such as Formula 2 can be prepared as disclosed in U.S. Patent Publication No. 2012/0258249, which is hereby incorporated by reference. Other glycol ether ester- compounds disclosed in U.S. Patent Publication No. 2012/0258249 can also be used as a coalescent in to some embodiments.

The coalescent, in some embodiments, comprises at least one of propylene glycol phenyl ether, ethylene glycol phenyl ether, dipropylene glycol n-butyl ether, ethylene glycol n-butyl ether benzoate, tripropylene glycol n-butyl ether, 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, Methylene glycol bis-2-ethylhexanoate, tributyl citrate, and/or the compound of Formula 2. Such coalescents are commercially available from The Dow Chemical Company (e.g., UCAR™ Filmer IBT), Eastman Chemical Company (e.g., Eastman Optifilm Enhancer 400), and others.

In some embodiments, aqueous coating compositions of the present invention further comprise one or more polyalkoxylates. In an aqueous coating composition of the present invention, such polyalkoxylates can allow the coating composition to stay wetter longer (i.e., extend the drying time). The one or more polyalkoxylates can be represented by the formula I- [AO _n H]f wherein I is an organic active hydrogen containing compound, AO is an alkylene oxide that comprises ethylene oxide (EO) or EO combined with propylene oxide (PO) and/or butylene oxide (BO) in a random order or in an oligomer having blocks, preferably, at least one block of EO, n is the total number of AO groups and f is the total number of active hydrogen groups in I, which ranges from 2 to 15 or, preferably, from 3 to 10, or, more preferably, from 3 to 8. Suitable active hydrogen compounds I for making the polyalkoxylates of the present invention may be chosen from diols, such as glycols, phenols having 2 hydroxyl groups, such as cresols; and difunctional aminoalcohols like diethanol amine; polyols having 3 or more hydroxyl groups, such as glycerol, pentaerythritol, sugar alcohol like sorbitol, xylitol or mannitol; diamines, such as ethylenediamine; triamines, such as diethylenetriamine; polyamines, such as polylysine or polyethylene imines; phenolic resins having from 2 to 15 or, preferably, from 2 to 8 or, preferably, 3 or more, hydroxyl groups, such as hydroxyl functional phenol formaldehyde resins; epoxy adducts of glycidyl ether with polyols; epoxy adducts of glycidyl ethers with diamines or polyamines, such as disecondary

diamines. Preferably, the active hydrogen compounds are polyols having 3 or more hydroxyl groups, difunctional aminoalcohols, diamines, triamines, polyamines and phenolic resins having 3 to 8 hydroxyl groups.

The ethylene oxide (EO) content of the one or more polyalkoxylates may be anywhere from 20 to 70 wt%, or, preferably, from 20 to 50 wt.%, based on the total weight of solids in the polyalkoxylate. The EO content should be sufficiently large to make the polyalkoxylate water dispersible, and yet low enough that the polyalkoxylates are little enough to be compatible with binder.

The number average molecular weight or Mn of the one or more polyalkoxylates may range from 800 to 10,000 or, preferably, 5,000 or less. Too high an Mn may result in gelling and/or flocculation or an aqueous composition containing the

polyalkoxylate. Preferably, the Mn of the one or more polyalkoxylates ranges 800 to 5000.

Examples of polyalkoxylates may include, for example, diethoxylated propylene glycol, triethoxylated glycerine, pentaethoxylated Methylene pentamine, ethoxylated alkyl phenol formaldehyde resins, Ci to Ci ₈ alk(en)ylamine (poly)alkoxylates, such as ethoxylated cocamine or tallow amine, Ci to Ci ₈ alk(en)yl diamine (poly)alkoxylates, such as ethoxylated tallow aminopropylamine, a Ci to Ci ₈ alk(en)ylamine (poly)alkoxylates, such as NINOL™ 40-CO Cocamide DEA (Stepan Company, Northfield, IL), ethoxylated cocamines available as Ethomeen™ C/12 or Ethomeen™ C/15 available from Akzo Nobel Chemicals Inc., Arnhem, Netherlands, and castor oil ethoxylates or propoxylates.

The one or more polyalkoxylates can be made in a conventional fashion by reacting the active hydrogen compound with ethylene oxide or a combination of ethylene oxide as well as propylene oxide and/or butylene oxide. The reaction of the active hydrogen compound with ethylene oxide to make the one or more polyalkoxylates can be carried out in a pressure reactor or autoclave at from 50 to 200 °C, or, preferably, from 90 to 150 °C at a pressure of from 100 to 2000 kPa . A basic catalyst may be used, such as sodium methanolate, an alkal metal hydroxide like NaOH or KOH.

As described below, the compound of Formula 1 and one or more coalescents can be provided as part of an aqueous coating composition. However, in some embodiments, a composition comprising the compound of Formula 1, wherein n = 3 to 10 (or 5 to 10, or 6 to 8, or 8), and one or more coalescents can be prepared as a composition, and such compositions can be provided to third parties. Such third parties might be, for example, manufacturers of aqueous coating compositions that can incorporate the composition comprising the Formula 1 compound and the coalescent(s) into their coating compositions. Thus, some embodiments of the present invention relate to compositions comprising the compound of Formula 1, wherein n = 3 to 10 (or 5 to 10, or 6 to 8, or 8), and the compound of Formula 2, wherein the composition comprises 30 to 70 percent by weight of Formula 1 and 30 to 70 percent by weight of Formula 2.

With regard to aqueous polymeric dispersions that can be included in aqueous coating compositions of the present invention, the aqueous polymeric dispersion may be a dispersion comprising a polymer, oligomer, prepolymer, or a combination thereof in an aqueous medium. In some embodiments, the aqueous polymeric dispersion forms a film upon evaporation of water and is not reactive. By "aqueous medium" is meant herein a medium including at least 50%, by weight based on the weight of the medium, water. The polymer, oligomer, prepolymer, or combination in the aqueous polymeric dispersion is often referred to as a binder. The choice of binder is not particularly critical, and the binder can be selected from all type of binders known in the art including, for example, styrene- acrylic, all acrylic, vinyl acrylic, and vinyl acetate polymeric binders, and hybrids of these and other chemistries. In one embodiment of the invention, the binder is a binder that is suitable for use for interior wall paint.

The average particle diameter of the polymer particles in the dispersion is not particularly critical, and advantageously is from 40 nm to 1000 nm, preferably from 40 nm to 300 nm. Particle diameters herein are those measured by dynamic light scattering on a Brookhaven BI-90 Plus particle size analyzer. In some embodiments, the invention includes an aqueous coating composition comprising: (a) a polymeric binder; (b) optionally, a pigment; (c) water; (d) the compound of Formula 1 as described hereinabove; and (e) at least one coalescent as described hereinabove. The coating composition can be employed in uses such as, for example, wall paints, floor coatings, ceiling paints, and window frame coatings.

The aqueous coating composition of the invention can be prepared by techniques which are well known in the coatings art. First, pigment(s), if any, are well dispersed in an aqueous medium under high shear, such as is afforded by a COWLES™ mixer, or predispersed colorant(s), or mixtures thereof are used. Then the aqueous polymeric dispersion is added under low shear stirring along with the compound of Formula 1 as described hereinabove, at least one coalescent, and other coatings adjuvants as desired. The aqueous coating composition may include, in addition to the aqueous polymeric dispersion and optional pigment(s), conventional coatings adjuvants such as, for example, extenders, emulsifiers, plasticizers, curing agents, buffers, neutralizers, rheology modifiers, humectants, biocides, antifoaming agents, UV absorbers, fluorescent brighteners, light and/or heat stabilizers, biocides, chelating agents, dispersants, colorants, waxes, and water- repellants.

The pigment can be selected from the wide range of materials known to those skilled in the art of coatings, including, for example, organic and inorganic colored pigments. Examples of suitable pigments and extenders include titanium dioxide such as anatase and rutile titanium dioxides; zinc oxide; antimony oxide; iron oxide; magnesium silicate;

calcium carbonate; aluminosilcates; silica; various clays such as kaolin and delaminated clay; and lead oxide. It is also contemplated that the aqueous coating composition may also contain opaque polymer particles, such as, for example, ROPAQUE™ Opaque Polymers (available from The Dow Chemical Company). Also contemplated are encapsulated or partially encapsulated opacifying pigment particles; and polymers or polymer emulsions adsorbing or bonding to the surface of pigments such as titanium dioxide such as, for example, EVOQUE™ polymers (available from The Dow Chemical Company); and hollow pigments, including pigments having one or more voids.

Titanium dioxide is the main pigment used to achieve hiding in architectural paints.

This pigment is expensive and in short supply. One way to achieve hiding while decreasing the amount of T1O2 is to include multistage emulsion polymers, commonly known as

"opaque polymers," that add opacity to the paint film. These polymers are water-filled emulsion polymer particles with a high T _g , such as particles polymerized using styrene as the predominant monomer. These particles fill with air during film formation and scatter light, thereby creating opacity.

The amounts of pigment and extender in the aqueous coating composition vary from a pigment volume concentration (PVC) of 0 to 85 and thereby encompass coatings otherwise described in the art, for example, as clear coatings, stains, flat coatings, satin coatings, semi-gloss coatings, gloss coatings, primers, textured coatings, and the like. The aqueous coating composition herein expressly includes architectural, maintenance, and industrial coatings, caulks, sealants, and adhesives. The pigment volume concentration is calculated by the following formula:

PVC (%) = (volume of pigment(s), + volume extender(s) x 100) / (total dry volume of paint).

The solids content of the aqueous coating composition may be from 10% to 70% by volume. The viscosity of the aqueous coating composition may be from 50 centipoises to 50,000 centipoises, as measured using a Brookfield viscometer; viscosities appropriate for different application methods vary considerably, as is known to those skilled in the art.

In use, the aqueous coating composition is typically applied to a substrate such as, for example, wood, metal, plastic, marine and civil engineering substrates, previously painted or primed surfaces, weathered surfaces, and cementitious substrates such as, for example, concrete, stucco, and mortar. The aqueous coating composition may be applied to a substrate using conventional coating application methods such as, for example, brush, roller, caulking applicator, roll coating, gravure roll, curtain coater and spraying methods such as, for example, air-atomized spray, air-assisted spray, airless spray, high volume low pressure spray, and air-assisted airless spray.

Drying of the aqueous coating composition to provide a coating may be allowed to proceed under ambient conditions such as, for example, at 5°C to 35°C or the coating may be dried at elevated temperatures such as, for example, from greater than 35 °C to 50°C.

Some embodiments of the invention will now be described in detail in the following Examples.

Examples

The following examples are given to illustrate the invention and should not be construed as limiting its scope. All parts and percentages are by weight unless otherwise indicated. Example 1

A batch of two gallons of a base paint formulation containing solids of 34 weight percent and a coalescent level of 8 weight percent, based on the polymer content of the aqueous polymeric dispersion, is prepared as described in Table 1 :

Table 1 - Base Paint Formulation for 2 Gallon Sample

The functions of each additive are as follows: Ti-Pure R-746 (titanium dioxide slurry, used as pigment); TAMOL™ 165 A (dispersant); TRITON™ GR-7M (surfactant, used as emulsifier and dispersant); Drewplus L-475 (foam control agent); RHOPLEX SG-10AF™ (aqueous polymeric dispersion); ACRYSOL RM-2020NPR and ACRYSOL RM-8W (rheology modifiers).

The components are added to a mix container in the order shown in Table 1 and as described below, and stirred by a variable speed mixer with an impeller attached. The grind portion of the formulation (order of addition: Ti-Pure R-746 slurry, water, TAMOL™ 165 A, and TRITON™ GR-7M) is added to the container, and the mixture is allowed to stir for 5 minutes. Each of the components are first weighed into a separate container on a balance and then poured into the mix container. The Let Down portion is added to the container in the following order: DrewPlus™ 475 followed by RHOPLEX™ SG10AF. The water, ACRYSOL™ RM-2020 NPR, and ACRYSOL™ RM-8W are added according to Table 3 because the viscosity (measured in Krebs Units or KU) is measured as the rheolog modifiers are added to adjust the batch according to target viscosities of 100-105 KU.

Different examples are then prepared using this base paint formulation, a freeze- thaw additive, and a coalescent as shown in Table 2:

Table 2

Rhodoline FT 100 is an existing free-thaw additive for waterborne paints, commercially available from Solvay. UCAR™ Filmer IBT is a 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate coalescent commercially available from The Dow Chemical Company.

The Examples shown in Table 2 are prepared by adding the specified freeze-thaw additive and coalescent to a 500 gram sample of the base paint formulation from Table 1. Table 3 shows the amounts that are post added to the base paint formulation for the Examples with 6% freeze-thaw additive and for the Examples with 8% freeze-thaw additive. Water is also added to complete the required amount for the formulation after addition of coalescent and freeze-thaw additive.

Table 3

The actual resin solids for the 500 gram sample of the base paint formulation is 124.9 grams. The amount of coalescent and freeze-thaw additive added to the base paint formulation is added to achieve the target weight percentages based on the solids in the base paint formulation.

The paint formulations containing the coalescent and freeze-thaw additive are subjected to 5 cycles of freezing and thawing. The samples are incubated at -23 °C overnight, and then allowed to thaw for approximately 8 hours. The samples are hand sheared with a tongue depressor for 100 stirs and the viscosity (KU) is measured. The results of this test are shown in Table 4.

Table 4

The data obtained for the Inventive Compositions (Inv. Comp. 1-2) are compared to comparative formulations (Compar. Comp. A-C) containing propylene glycol or alkoxylated tristyrylphenol (TSP) (Rhodoline FT- 100) as freeze-thaw additives, and UCAR™ Filmer IBT as coalescents.

The paint formulation containing propylene glycol (Compar. Comp. A) failed the test after the first freezing and thawing cycle with a viscosity >150 KU that could not be measured. In contrast, the formulations prepared with the compound of Formula 1 passed the full 5 freeze-thaw cycles with only small increases in viscosity, and compared well with the formulations prepared with the TSP ethoxylate freeze-thaw additive (Compar. Comps. B-C). It should be noted that no effort was made to adjust the initial viscosity to a single value and instead just the net change on viscosity after freezing and thawing cycles is considered for comparison purposes.