Polymer dispersions, method of manufacturing same, and coating compositions including such polymer dispersions

Abstract

A polymer dispersion including a first-formed soft stage and a second-formed hard stage. The first-formed soft stage includes a first polymer having a Tg of -50˚C to 20˚C, a weight average molecular weight of about 40,000 g / mol to about 130,000 g / mol and an acid number between about 35 mg KOH / g to about 70 mg KOH / g. The second-formed hard stage includes a second polymer having a Tg of about 21˚C to about 100˚C. A weight ratio of the first polymer to the total of the first and second polymers is about 10% to about 90%, and a weight ratio of the second polymer to the total of the first and second polymers is about 90% to about 10%. A coating composition including such a polymer dispersion, and the coating composition may be a decorative coating composition.

Description

POLYMER DISPERSIONS, METHOD OF MANUFACTURING SAME, AND COATING COMPOSITIONS INCLUDING SUCH POLYMER DISPERSIONS

[0001] FIELD OF THE INVENTION

[0002] The invention relates to polymer dispersions with improved surfactant leaching resistance, block resistance and body lotion resistance, and coating compositions including such polymer dispersions. The invention also relates to manufacturing processes for such polymer dispersions and coating compositions.

[0003] BACKGROUND OF THE INVENTION

[0004] Acrylic latex has many applications, including coatings, adhesives, home care, personal care, construction, paper, inks, and the like. Acrylic latexes are manufactured via emulsion polymerization of acrylic monomers. During the emulsion polymerization process, surfactants are often used to stabilize the latex particles. When latex is used in pigmented coating systems, larger amounts of surfactants (along with other hydrophilic materials such as dispersing agents) are added to stabilize the pigment and colorant. Once the latex-based product has been applied to a surface as part of a protective or decorative coating, the surfactant is no longer needed. In fact, the presence of surfactants (and other hydrophilic materials) in the paint film negatively affects the desired properties, such as adhesion and moisture resistance, of the coating. These surfactants may also leach out from the paint surface during the drying process, leaving a water mark on the surface. It is typically understood that this negative effect is largely due to the mobility of the surfactant. For example, a locally high concentration of surfactant can form in the coating from the coalescence of the surfactant-coated micelle particles. When the coatingis exposed to water or high humidity conditions, these surfactant molecules can migrate to the coating surface and create an undesirable water mark.

[0005] Protective or decorative coating compositions also have to meet a challenging set of performance criteria to be effective and successful. These performance criteria include excellent adhesion to unprimed surfaces, excellent weatherability, ability to resist corrosion of the surfaces to which they are applied, good block resistance and low content of volatile organic compounds (VOC).

[0006] Permissible VOC levels in coating compositions continues to decrease because of increasingly stringent environmental regulations and increasing consumer awareness. However, a major source of the VOC components in waterborne coating compositions are coalescing agents. A typical solution to minimize the amount of coalescing agents, while maintaining good coalescence, is to reduce the glass transition temperature (Tg) of the polymer particles in the coating compositions. However, polymers having a low Tg tend to reduce block resistance of the coating. Therefore, a key challenge for low VOC containing waterborne coating systems is achieving good block resistance while concurrently achieving sufficient coalescence, both of which are key performance requirements for many coating applications.

[0007] Two-stage polymer-based latexes (such as core-shell structured latex) are often used to increase the block resistance properties while still meeting strict low VOC requirements. However, such two-staged polymer-based latexes often have poor film formation compared to single-staged latex due to the incompatible hard and soft phases, which in turn leads to poor surfactant leaching properties.

[0008] Historically, the properties needed for good block resistance and a rapid and complete coalescing of the coating composition have been at odds, i.e., low VOC coating compositions having a good blocking property tend to be slow to coalesce, and vice versa because low-VOC coalescing agents (or simply using less coalescing agent) tend to reduce block resistance. The problem the inventors are seeking to solve is to improve the coating block resistance and surfactant leaching resistance properties while still maintaining a low VOC level, as well as other improved properties described herein.

[0009] There is also a growing interest in preparation of coating compositions that can withstand damage from personal care products, such as body lotions and other skin care products For example, body lotions are topical products that are typically used to moisturize and soften skin. Such topical products are usually applied after bathing or showering to hydrate the skin, prevent dryness, and provide a smooth, soft texture. Body lotions often contain a combination of water, oils, humectants (which help retain moisture), emollients (which soften the skin), and may also include fragrances or additional skincare ingredients like vitamins or antioxidants. Most such humectants and / or emollients, which are often oily or greasy, have plasticizer functionality, which can plasticize a coating film, and soften the film hardness. This can result in discoloration, softening, or removal of a coating when exposed to such substances. " Body lotion resistance" refers to a coating's ability to withstand the staining or degradation effects caused by contact with body lotions or similar personal care products.

[0010] US 2020 / 354603 describes a coating composition comprising one or more latex polymers, at least one alkali-soluble resin, and at least one pigment.

[0011] US 2022 / 0235272 A1 describes suppressing surfactant leaching by using reactive surfactants, or “polymerizable surfactants,” during an emulsion polymerization to prevent free forms of the surfactant in the product or intermediary product.

[0012] US 8,013,050 describes a waterborne curable multistage polymer dispersion including a first stage polymer and a second stage polymer, where the first stage polymer is partially neutralized with a base before feeding the second stage monomer into the system.

[0013] US 8,530,362 describes a composition comprising acrylic oligomers and aqueous carboxylic acid group containing acrylic polymers.

[0014] US 9,951,169 describes an aqueous coating composition that combines a highly acid-containing, alkali-soluble oligomer with an emulsion polymer.

[0015] US 10,538,675 B2 describes a polymeric paint additive that increases the open time and the flow and leveling of paint compositions.

[0016] US 11,299,574 describes an architectural paint comprising one or more latex polymers.

[0017] US 11,685,800 B2 describes multi-stage, “core-shell” type polymers that includes a hard phase polymer as the core and a soft phase polymer as the shell.

[0018] CN 112143323 B describes a waterproof, exterior wall coating material that can avoid rain mark generation and includes an acrylic acid-based reactive emulsifier, an unsaturated silicon-based chlorinated straw material, a pigment, and a filler.

[0019] EP 0 338486 describes a process for producing a stabilized latex characterized by the first-stage polymer being water-soluble upon pH adjustment.

[0020] EP 0 758 347 describes a process to produce an organic solvent-free aqueous crosslinkable polymer composition, which includes an acid-functional oligomer that becomes water-soluble upon neutralization.

[0021] JP 6031248 B2 describes a coating material composition that includes a synthetic resin emulsion as a binding material and includes a filler, a thickener, and a pigment, and the coating material does not generate a watermark with water after coating.

[0022] WO 19 / 060614 A1 describes an aqueous coating composition with reduced surface leaching that includes a carbosiloxane dendrimer-grafted vinyl copolymer emulsion composition.

[0023] WO 21 / 022534 A1 describes an aqueous dispersion based on ethylene-vinyl ester copolymers that features good long-term storage stability and weakens the watermark phenomenon on the coating film when it is used in waterborne architectural coatings.

[0024] None of these referenced documents discloses the multi-stage polymeric particles described herein that have the effective combination of good block resistance, good body lotion resistance, low surfactant leaching properties and low VOC content.

[0025] SUM MARY OF THE INVENTION

[0026] The invention relates to a polymer dispersion including multi-stage polymeric particles having a first-formed soft stage and a second-formed hard stage. The invention also provides for methods to form these particles as well as coating compositions that include a polymer dispersion of such particles.

[0027] An exemplary embodiment is directed to a polymer dispersion including a first-formed soft stage and a second-formed hard stage, where the first-formed soft stage includes a first polymer having a Tg of -50°C to 20°C, a weight average molecular weightof 40,000 grams per mole (g / mol) to 130,000 g / mol and an acid number between 35 mg KOH / g to 70 mg KOH / g, the second-formed hard stage comprises a second polymer having a Tg of 21°C to 100°C, a weight ratio of the first polymer to the total of the first and second polymers is 10% to 90%, and a weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

[0028] Another exemplary embodiment is directed to a method for forming polymeric particles, where the method comprises the steps of: feeding a first monomer mixture to a reactor vessel; initiating a free radical polymerization, at a pH of from 2 to 9, of the first monomer mixture to form a first stage of the polymeric particles, the first-formed stage including a first polymer comprising the first monomer mixture as polymerized units; feeding a second monomer mixture to the reactor vessel; polymerizing, at a pH of from 2 to 9, the second monomer mixture in the presence of the first-formed stage to form a second stage of the polymeric particles, the second stage including a second polymer including the second monomer mixture as polymerized units; where the polymeric particles includes the first polymer and the second polymer; the first polymer has a Tg of -50°C to 20°C, a weight average molecular weight of 40,000 g / mol to 130,000 g / mol and an acid number between 35 mg KOH / g to 70 mg KOH / g; the second polymer has a Tg of 21°C to 100°C; a weight ratio of the first polymer to the total of the first and second polymers is 10% to 90%; and a weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

[0029] Another exemplary embodiment is directed to a coating composition that includes a coalescing agent; and a waterborne emulsion comprising polymeric particles described herein, where the coating composition has a volatile organic compound content of lessthan 100 grams per liter of the coating composition and the coating composition has a minimum film forming temperature of less 15°C.

[0030] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0031] BRIEF DESCRIPTION OF THE DRAWING

[0032] Drawings are provided herewith for better understanding of the invention, and illustrate the principles and features of the invention. The Drawings are not necessarily to scale and are not meant to limit the invention. In the Drawings, like numerals are used to indicate like parts throughout the various views.

[0033] The Figure is a graphical representation of Body Lotion Resistance of a coating including the polymer dispersion of Example 1 compared to the Body Lotion Resistance of commercial paint samples.

[0034] DETAILED DESCRIPTION OF THE INVENTION

[0035] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses.

[0036] Unless indicated otherwise, each individual feature, aspect, or embodiment described herein is combinable with any other individual feature(s), aspect(s) or embodiment(s) that is / are described herein, without limitation. Such combinations are specifically contemplated as being within the scope of the present invention, regardless of whether they are explicitly described as a combination herein

[0037] Any compositions described herein are intended to encompass compositions which consist of, consist essentially of, as well as comprise, the various constituents identified herein, unless explicitly indicated to the contrary.

[0038] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Additionally, the use of “or” is intended to include “and / or”, unless the context clearly indicates otherwise.

[0039] As used herein, the recitation of a numerical range for a variable is intended to convey that the variable can be equal to any value(s) within that range, any and all subranges encompassed by the broader range, including any integer value(s) within that range as well as the upper and lower limits unless explicitly indicated to the contrary.

[0040] As used herein, "about" is a term of approximation that would be understood by one of skill in the art, and is intended to include minor variations such as, for example, standard deviations associated with techniques commonly used to measure the amounts of the constituent elements or components of an alloy or composite material, or other properties and characteristics. All of the values characterized by the above-described modifier "about," are also intended to include the exact numerical values disclosed herein. Moreover, all ranges include the upper and lower limits.

[0041] As used herein, the terms “polymer dispersion” and “polymer particles” may be considered to be interchangeable.

[0042] As used herein, the term “theoretical Fox Equation glass transition temperature” or “theoretical Fox equation Tg” or “Tg” may be considered to be interchangeable, and refers to the estimated Tg of a polymer or copolymer calculated using the Fox equation. The Fox equation can be used to estimate the glass transition temperature of a randompolymer or copolymer. The theoretical glass transition temperature Tg of a copolymer derived from monomers 1, 2,..., i can be calculated according to Equation (I):

[0043] ^ = (I), where wi is the weight fraction of monomer i in thecopolymer.

[0044] Unless otherwise indicated, all percentages herein are weight percentages.

[0045] The terms “layer” and “shell” and “stage” as used herein may be considered to be interchangeable.

[0046] The terms “paint” and “coating” as used herein may be considered to be interchangeable.

[0047] Technical and scientific terms used herein have the meaning commonly understood by one of skill in the art to which the present description pertains, unless otherwise defined.

[0048] Described herein is a polymer dispersion comprising multi-stage polymeric particles that have the effective combination of good block resistance, good body lotion resistance, low surfactant leaching properties and low VOC content, a method of preparing such particles, and a coating composition including such polymer dispersions.

[0049] The polymeric dispersion include a) a first-formed soft stage including a first polymer and b) a second-formed hard stage including a second polymer.

[0050] The first (soft stage) polymer may have a theoretical Fox equation Tg of from about 20°C to about -50°C, or from about 20°C to about -40°C, or from about 20°C to about -30°C, or from about 20°C to about -20°C, or from about 20°C to about -10°C, or from about 15°C to about -40°C, or from about 10°C to about -30°C, or from about 10°C to about -50°C, or from about 10°C to about -40°C, or from about 10°C to about -30°C, or from about10°C to about -20°C, or from about 10°C to about -10°C, or from about 5°C to about -50°C, or from about 5°C to about -40°C, or from 5°C to about -30°C, or from about 5°C to about -20°C, or from about 0°C to about -45°C, or from about 0°C to about -20°C, or from about -5°C to about -40°C, or from about -5°C to about -30°C, or from about -5°C to about -20°C, or from about -10°C to about -40°C, or from about -10°C to about -20°C, or from about -10°C to about -30°C, or from about -10°C to about -40°C, or from about -15°C to about -45°C, or from about -15°C to about -35°C, or from about -15°C to about -25°C, or from about -20°C to about -50°C, or from about -20°C to about -40°C, or from about -20°C to about -30°C, about 20°C, about 15°C, about 10°C, about 12.5°C, about 5°C, about 2.5°C, about 0°C, about -2.5°C, about -5°C, about -10°C, about -12.5°C, about -15°C, about -30°C, about -40°C, about -50°C, and the like. The Tg of the first (soft stage) polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0051] The second (hard stage) polymer may have a theoretical Fox equation Tg of from about 21°C to about 100°C, or from about 10°C to about 75°C, or from about 10°C to about 50°C, or from about 10°C to about 25°C, or from about 20°C to about 100°C, or from about 20°C to about 75°C, or from about 20°C to about 50°C, or from about 30°C to about 100°C, or from about 30°C to about 75°C, or from about 30°C to about 50°C, or from about 35°C to about 100°C, or from 35°C to 90°C, or from about 35°C to about 75°C, or from about 35°C to about 50°C, or from about 40°C to about 100°C, or from about 40°C to about 80°C, or from about 50°C to about 60°C, or from about 45°C to about 100°C, or from about 45°C to 70°C, or from about 45°C to about 60°C, or from 50°C to about 100°C, or from about 50°C to about 80°C, or from about 50°C to about 60°C, about 10°C, about12.5°C, about 15°C, about 17.5°C, about 20°C, about 25°C, about 30°C, about 35°C, about 37.5°C, about 40°C, about 42.5°C, about 45°C, about 47.5°C, about 50°C, about 51°C, about 52°C, about 53°C, about 54°C, about 55°C, about 56°C, about 57°C, about 58°C, about 59°C, about 60°C, about 70°C, about 80°C, about 90°C, about 100°C, and the like. The Tg of the second (hard stage) polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0052] Adjusting the amount of different monomers in a copolymer can be used to tailor the Tg value of the copolymer. The various monomers described herein can be included in the first- and second-stage polymer, respectively, to achieve a theoretical Fox equation Tg of from about 20°C to about -50°C of the first-stage polymer and a theoretical Fox equation Tg of from about 21°C to about 100°C of the second-stage polymer.

[0053] The soft and hard stage polymer may have two different Tg values as measured by modulated differential scanning calorimetry methods. The difference in Tg values between the soft and hard stage polymers may be at least about 10°C, at least about 20°C, at least about 30°C, at least about 40°C, at least about 50°C, at least about 60°C, and the like, and such difference is not more than 150°C. The different in Tg between the soft and hard stage polymers can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0054] The first (soft stage) polymer may have a weight average molecular weight, as measured by Gel Permeation Chromatography (GPC) according to the method described herein, ranging from about 40,000 g / mol to about 130,000 g / mol, or from about 40,000 g / mol to about 110,000 g / mol, or from about 40,000 g / mol to about 90,000 g / mol, or from about 40,000 g / mol to about 70,000 g / mol, or from about 50,000 g / mol to about 130,000g / mol, or from about 50,000 g / mol to about 110,000 g / mol, or from about 50,000 g / mol to about 90,000 g / mol, or from about 50,000 g / mol to about 70,000 g / mol, or from about 60,000 g / mol to about 130,000 g / mol, or from about 60,000 g / mol to about 110,000 g / mol, or from about 60,000 g / mol to about 90,000 g / mol, or from about 70,000 g / mol to about 130,000 g / mol, or from about 70,000 g / mol to about 90,000, g / mol or about 40,000 g / mol, or about 45,000 g / mol, or about 46,000 g / mol, or about 47,000 g / mol, or about 48,000 g / mol, or about 49,000 g / mol, or about 50,000 g / mol, or about 55,000 g / mol, or about 60,000 g / mol, or about 65,000 g / mol, or about 70,000 g / mol, or about 75,000 g / mol, or about 80,000 g / mol, or about 85,000 g / mol, or about 90,000 g / mol, or about 95,000 g / mol, or about 96,000 g / mol, or about 97,000 g / mol, or about 98,000 g / mol, or about 99,000 g / mol, or about 100,000 g / mol, or about 105,000 g / mol, or about 110,000 g / mol, or about 115,000 g / mol, or about 120,000 g / mol, or about 125,000 g / mol, or about 130,000 g / mol, and the like. The weight average molecular weight of the first polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0055] The molecular weight of the second (hard stage) polymer is not limited, and any suitable hard stage polymer may be used. In a preferred embodiment, the weight average molecular weight of the second stage polymer is higher than the molecular weight of the first stage polymer.

[0056] The weight ratio of the first polymer to the total weight of the first and second polymers can be from about 10 wt% to 90 wt%, or from about 10 wt% to about 75 wt%, or from about 10 wt% or about 50 wt%, or from about 10 wt% to about 25 wt%, or from about 20 wt% to 80 wt%, or from about 20 wt% to about 60 wt%, or from about 20 wt% to about 40 wt%, from about 30 wt% to about 70 wt%, or from about 30 wt% to about 60wt%, from about 30 wt% to about 50 wt%, from about 30 wt% to about 40 wt%, from about 40 wt% to about 60 wt%, or from about 40 wt% to about 50 wt%, or from about 50 wt% to about 60 wt%, or from about 50 wt% to about 75 wt%, or from about 45 wt% to about 55 wt%, or about 15 wt%, or about 25 wt%, or about 30 wt%, or about 44.2 wt%, or about 44.4 wt%, or about 44.6 wt%, or about 44.8 wt%, or about 45 wt%, or about 60 wt%, or about 75 wt%, and the like. The weight ratio of the first polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0057] The weight ratio of the first polymer to the total weight of the first and second polymers can be from about 90 wt% to 10 wt%, or from about 90 wt% to about 25 wt%, or from about 90 wt% to about 50 wt%, or from about 90 wt% to about 75 wt%, or from about 80 wt% to about 10 wt%, or from about 80 wt% to about 20 wt%, or from about 80 wt% to about 30 wt%, or from about 80 wt% to about 50 wt%, or from about 70 wt% to about 10 wt%, or from about 70 wt% to about 20 wt%, or from about 70 wt% to about 30 wt%, or from about 70 wt% to about 40 wt%, or about 70 wt% to about 50 wt%, or from about 60 wt% to about 10 wt%, or from about 60 wt% to about 30 wt%, or from about 60 wt% to about 40 wt%, or from about 55 wt% to about 15 wt%, or from about 55 wt% to about 25 wt%, or from about 55 wt% to about 45 wt%, or about 85 wt%, or about 80 wt%, or about 75 wt%, or about 70 wt%, or about 65 wt%, or about 60 wt%, or about 55 wt%, or about 50 wt%, or about 45 wt%, or about 40 wt%, or about 35 wt%, or about 30 wt%, or about 25 wt%, or about 20 wt%, or about 15wt%, or about 10 wt%, and the like, of the second polymer. The weight ratio of the second polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0058] In one embodiment, the total of the weight % of the soft polymer phase and the weight % of the hard polymer phase is 100%.

[0059] A total solids content of the two-stage polymer may range from about 30 wt% to about 70 wt%, or from about 35 wt% to about 65 wt%, or from about 40 wt% to about 60 wt%, or from about 45 wt% to about 55 wt%, or about 32 wt%, or about 34 wt%, or about 36 wt%, or about 38 wt%, or about 42 wt%, or about 44 wt%, or about 46 wt%, or about 48 wt%, and the like. The total solids content can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0060] The first (soft stage) polymer may have an acid number as measured according to the method described herein from about 35 mg KOH / g to about 70 mg KOH / g, or from about 36 mg KOH / g to about 69 mg KOH / g, or from about 37 mg KOH / g to about 68 mg KOH / g, or from about 38 mg KOH / g to about 67 mg KOH / g, or from about 39 mg KOH / g to about 66 mg KOH / g, or from about 40 mg KOH / g to about 65 mg KOH / g, or from about 50 mg KOH / g to about 60 mg KOH / g, or about 35 mg KOH / g, or about 40 mg KOH / g, or about 41 mg KOH / g, or about 42 mg KOH / g, or about 43 mg KOH / g, or about 44 mg KOH / g, or about 45 mg KOH / g, or about 46 mg KOH / g, or about 47 mg KOH / g, or about 48 mg KOH / g, or about 49 mg KOH / g, or about 50 mg KOH / g, or about 55 mg KOH / g, or about 60 mg KOH / g, or about 65 mg KOH / g, or about 70 mg KOH / g, and the like. The acid number of the first polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0061] The D50 particle size of the polymer particles can vary. In various embodiments of the invention, the particles may have an average diameter of less than about 350 nm, or less than about 340 nm, or less than about 330 nm, or less than about 325 nm, or lessthan about 320 nm, or less than about 310 nm, or less than about 300 nm, or less than about 290 nm, or less than about 280 nm, or less than about 275 nm, or less than about 270 nm, or less than about 260 nm, or less than about 250 nm, or less than about 240 nm, or less than about 230 nm, or less than about 225 nm, or less than about 200 nm, or less than about 175 nm, or less than about 150 nm, or about 350 nm, or about 300 nm, or about 250 nm, or about 200 nm, or about 150 nm, or about 100 nm, or about 99 nm, or about 98 nm, or about 97 nm, or about 96 nm, or about 95 nm, or about 94 nm, or about 93 nm, or about 92 nm, or about 91 nm, or about 90 nm, or about 89 nm, or about 88 nm, or about 87 nm, or about 86 nm, or about 85 nm, or about 84 nm, or about 83 nm, or about 82 nm, or about 81 nm, or about 80 nm, and the like. In various desirable embodiments of the invention, the particles have an average diameter of more than about 50 nm, more than about 55 nm, more than about 60 nm, more than about 65 nm, more than about 70 nm, more than about 75 nm, more than about 80 nm, or about 50 nm, or about 52 nm, or about 54 nm, or about 56 nm, or about 58 nm, or about 62 nm, or about 64 nm, or about 66 nm, or about 68 nm, or about 72 nm, or about 74 nm, or about 76 nm, or about 78 nm, and the like. The size of the polymer particles can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges. The D50 particle size is a measure of the particle size distribution corresponding to the cumulative frequency 50%, i.e., the particle size at which 50% of the particles are larger and 50% are smaller than the D50 value.

[0062] Particle size and particle size distribution of the polymer dispersion may be analyzed using Nanotrac UPA 150 (from Microtrac Inc.) to provide volume-averaged particle sizes based on dynamic light scattering techniques. Typically, the multi-stageparticles may be approximately spherical in shape, although oblong, oval, teardrop or other shapes are also possible. In an embodiment of the invention, the soft polymer phase is an inner (core) phase within the polymer particles and the hard polymer phase is an outer (shell) phase of the polymer particles.

[0063] FREE RADICAL POLYMERIZABLE ETHYLENICALLY UNSATURATED MONOMERS i) AND iv):

[0064] The first-formed soft stage of the multi-stage polymer particles may comprise, as polymerized units based on the dry weight of the first polymer, i) one or more free radical polymerizable ethylenically unsaturated monomers. The second-formed hard stage of the multi-stage polymer particles may comprise, as polymerized units based on the dry weight of the second polymer, iv) one or more free radical polymerizable ethylenically unsaturated monomers.

[0065] Non-limiting examples of suitable polymerizable ethylenically unsaturated monomers i) and iv) that may be used to form the first-formed soft stage and the second-formed hard stage, respectively, of the multi-stage polymer particles include: branched and linear (C1 -C20) alkyl or (C3-C20) alkenyl esters of (meth)acrylic acid, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate and the like, vinyl aromatic monomers such as styrene, a-methyl styrene, p-methyl styrene, t-butyl styrene, or vinyltoluene, olefins such as ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, (meth)acrylonitrile, and (meth)acrylamide, for example. Preferred monomers are methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, styrene, butyl(meth)acrylate, ethyl (meth)acrylate, benzyl (meth)acrylate, glycidyl methacrylate, 3-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane and mixtures thereof. Most preferred monomers are styrene, methyl methacrylate, 2-ethylhexyl acrylate, butyl acrylate, and mixtures thereof.

[0066] Mixtures of any or all of the above free-radical polymerizable monomers may be included in either or both of the first and second polymers.

[0067] In one embodiment, the free radical polymerizable ethylenically unsaturated monomers i) and iv) of the first and second polymers, respectively, may be the same. In another embodiment, the second monomer mixture of the second polymer differs from the first monomer mixture of the first polymer in at least one of type or relative amount of the free radical polymerizable monomer.

[0068] The one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer may be selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof. The one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

[0069] According to some embodiments, preferred monomers are methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, styrene, butyl (meth)acrylate, ethyl (meth)acrylate, benzyl (meth)acrylate and mixtures thereof. According to some embodiments, most preferred monomers are styrene, methyl methacrylate, 2-ethylhexyl acrylate, butyl acrylate, butyl methacrylate and mixtures thereof.

[0070] In an embodiment, the free radical polymerizable ethylenically unsaturated monomer i) may be included in the first polymer in an amount of from about 70 wt% to about 99.99 wt%, or from about 75 wt% to about 95 wt%, or from about 80 wt% to about 90 wt%, or about 72 wt%, or about 74 wt%, or about 76 wt%, or about 78 wt%, or about 82 wt%, or about 84 wt%, or about 86 wt%, or about 88 wt%, or about 92 wt%, or about 94 wt%, or about 96 wt%, or about 98 wt%, and the like, based on the dry weight of the first polymer. The amount of the free radical polymerizable ethylenically unsaturated monomer (i) in the first polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0071] In an embodiment, the free radical polymerizable ethylenically unsaturated monomer iv) may be included in the second polymer in an amount of from about 80 wt% to about 100 wt%, or from about 85 wt% to about 95 wt%, or from about 92 wt% to about 98 wt%, or from about 94 wt% to about 96 wt%, or about 91 wt%, or about 93 wt%, or about 95 wt%, or about 97 wt%, or about 99 wt%, and the like, based on the dry weight of the second polymer. The amount of the free radical polymerizable ethylenically unsaturated monomer iv) of the second polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0072] ACID MONOMER

[0073] The first-formed soft stage of the multi-stage polymer particles may comprise, as polymerized units based on the dry weight of the first polymer, ii) one or more acid monomers.

[0074] Non-limiting examples of suitable acid monomers (ii) that may be used to form the first-formed soft stage include carboxylic acid monomers. In preferred embodiments, theacid monomer may be selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, linolenic acid, 3-butenoic acid, and the like. The second polymer is preferably free of acid monomer.

[0075] Mixtures of any or all of the above acid monomers may be included in the first polymer.

[0076] In an embodiment, the acid monomer (ii) may be included in the first polymer in an amount of from about 0.1 wt% to about 20 wt%, or from about 0.5 wt% to about 15 wt%, or from about 1 wt% to about 12 wt%, or from about 1.5 wt% to about 11 wt%, or from about 2 wt% to about 10.5 wt%, or from about 2.5 wt% to about 10 wt%, or from about 3 wt% to about 9.5 wt%, or from about 3.5 wt% to about 9 wt%, or from about 4 wt% to about 8.5 wt%, or from about 4.5 wt% to about 8 wt%, or from about 5 wt% to about 7.5 wt%, or about 0.75 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.75 wt%, or about 3.25 wt%, or about 3.75 wt%, or about 4.25 wt%, or about 4.75 wt%, or about 5.25 wt%, or about 5.5 wt%, or about 5.75 wt%, or about 6.25 wt%, or about 6.5 wt%, or about 6.75 wt%, or about 7.25 wt%, or about 7.75 wt%, or about 8.25 wt%, or about 8.5 wt%, or about 8.75 wt%, or about 9.25 wt%, or about 9.75 wt%, or about 10.5 wt%, and the like, based on the dry weight of the first polymer. The amount of the acid monomer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0077] FREE RADICAL POLYMERIZABLE MONOMER HAVING A BETA DICARBONYL FUNCTIONALITY:

[0078] The first-formed soft stage of the multi-stage polymer particles may comprise, as polymerized units based on the dry weight of the first polymer, iii) one or more monomershaving a beta dicarbonyl functionality. The second-formed hard stage of the multi-stage polymer particles may comprise, as polymerized units based on the dry weight of the second polymer, v) one or more monomers having a beta dicarbonyl functionality.

[0079] Non-limiting examples of suitable free radical polymerizable monomers iii) and v) having a beta dicarbonyl functionality that may be used to form the first-formed soft stage and the second-formed hard stage of the multi-stage polymer particles include: acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, diacetone acrylamide, and combinations thereof. A preferred free radical polymerizable monomer having a beta dicarbonyl functionality is diacetone acrylamide (DAAM).

[0080] Mixtures of any or all of the above free-radical polymerizable monomers may be included in either or both of the first and second polymers.

[0081] In one embodiment, the free radical polymerizable monomers iii) and v) of the first and second polymers, respectively, may be the same. In another embodiment, the second monomer mixture of the second polymer differs from the first monomer mixture of the first polymer in at least one of type or relative amount of the free radical polymerizable monomer having a beta dicarbonyl functionality.

[0082] In an embodiment, the free radical polymerizable monomer iii) having a beta dicarbonyl functionality may be included in the first polymer in an amount of from about 0 wt% to about 10 wt%, or from about 0 wt% to about 9 wt%, or from about 0 wt% to about8 wt%, or from about 0.01 wt% to about 7 wt%, or from about 0.01 wt% to about 6 wt%, or from about 0.01 wt% to about 5 wt%, or from about 0.01 wt% to about 4 wt%, or from about 0.05 wt% to about 4 wt%, or from about 0.1 wt% to about 4 wt%, or from about 0.15 wt% to about 3.5 wt%, or from about 0.2 wt% to about 3 wt%, or from about 0.3 wt% to about 2.5 wt%, or from about 0.4 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.175 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.5 wt%, or about 2.75 wt%, or about 3.25 wt%, or about 3.75 wt%, or about 4.5 wt%, or about 5.5 wt%, or about 6.5 wt%, or about 7.5 wt%, or about 8.5 wt%, or about 9.5 wt%, and the like, based on the dry weight of the respective first or second polymer. The amount of the free radical polymerizable monomer iii) having beta dicarbonyl functionality in the first polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0083] In an embodiment, the free radical polymerizable monomer v) having a beta dicarbonyl functionality may be included in the second polymer in an amount of from about 0 wt% to about 10 wt%, or from about 0 wt% to about 9 wt%, or from about 0 wt% to about 8 wt%, or from about 0.01 wt% to about 7 wt%, or from about 0.01 wt% to about 6 wt%, or from about 0.01 wt% to about 5 wt%, or from about 0.01 wt% to about 4 wt%, or from about 0.05 wt% to about 4 wt%, or from about 0.1 wt% to about 4 wt%, or from about 0.15 wt% to about 3.5 wt%, or from about 0.2 wt% to about 3 wt%, or from about 0.3 wt% to about 2.5 wt%, or from about 0.4 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.175 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.5 wt%, orabout 2.75 wt%, or about 3.25 wt%, or about 3.75 wt%, or about 4.5 wt%, or about 5.5 wt%, or about 6.5 wt%, or about 7.5 wt%, or about 8.5 wt%, or about 9.5 wt%, and the like, based on the dry weight of the respective first or second polymer. The amount of the free radical polymerizable monomer v) having the beta dicarbonyl functionality in the second polymer can be equal to any integer value(s) within any of these ranges, including the end-points of these ranges.

[0084] ADDITIONAL COMPONENTS:

[0085] Any suitable chain transfer agent may be used in the polymerization of the first and second polymers of the multi-stage emulsion polymer particles. Non-limiting examples of such chain transfer agents include isooctyl 3-mercaptopropionate (IOMP), dodecyl mercaptan (DDM), n-butyl mercaptan, tert-dodecyl mercaptan, 2-ethylhexyl mercaptan, methyl mercaptan, carbon tetrachloride, carbon tetrabromide, dibenzoyl peroxide, dithioesters, trithiocarbonates, dithiocarbamates, xanthates, 1,8-dimercapto-3,6-dioxaoctane (DMDO), pentaerythritol tetrakis(2-mercaptoacetate), and the like.

[0086] The amount of the chain transfer agent may be, for example, from about 0.01 wt% to about 5 wt%, or from about 0.05 wt% to about 4.5 wt%, or from about 0.1 wt% to about 4 wt%, or from about 0.2 wt% to about 3.5 wt%, or from about 0.3 wt% to about 3 wt%, or from about 0.35 wt% to about 2.5 wt%, or from about 0.4 wt% to about 2 wt%, or from about 0.45 wt% to about 1.75 wt%, or from about 0.5 wt% to about 1.5 wt%, or from about 0.5 wt% to about 1 wt%, or from about 0.5 wt% to about 0.75 wt%, and the like, based on the total amount of monomer. The amount of chain transfer agent can be equal to any integer value(s) within this range, including the end-points of these ranges. The type andamount of chain transfer agent may be the same or different in the various stages of the multi-stage polymerization.

[0087] The free radical initiators suitable for the polymerization of the monomers used to prepare the multi-stage emulsion polymer particles as described herein may be any water soluble initiator suitable for aqueous emulsion polymerization. Examples of free radical initiators suitable for the preparation of any of the shell layers of the multi-stage emulsion polymer particles of the present application include hydrogen peroxide, tert-butyl peroxide, alkali metal persulfates such as sodium, potassium and lithium persulfate, ammonium persulfate, and mixtures of such initiators with a reducing agent.

[0088] The amount of initiator may be, for example, from about 0.01 to about 3 percent by weight (wt%), or from about 0.05 wt% to about 2.5 wt%, or from about 0.1 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.15 wt%, or about 0.175 wt%, or about 0.15 wt%, or about 0.3 wt%, or about 0.7 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.75 wt%, and the like, based on the total amount of monomer. The amount of initiator can be equal to any integer value(s) within this range, including the end-points of these ranges.

[0089] The type and amount of initiator may be the same or different in the various stages of the multi-stage polymerization.

[0090] In some embodiments, a redox polymerization initiator system may be used. In a redox free radical initiation system, a reducing agent may be used in conjunction with an oxidant. Reducing agents suitable for the aqueous emulsion polymerization include sulfites (e.g., alkali metal metabisulfite, hydrosulfite, and hyposulfite). In someembodiments, sugars (such as ascorbic acid and isoascorbic acid or an alkali metal (iso)ascorbate salt) might also be a suitable reducing agent for the aqueous emulsion polymerization.

[0091] In a redox system, the amount of reducing agent may be, for example, from about 0.01 wt% to about 3 wt%, or from about 0.05 wt% to about 2.5 wt%, or from about 0.1 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.15 wt%, or about 0.175 wt%, or about 0.15 wt%, or about 0.3 wt%, or about 0.7 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.75 wt%, and the like, based on the total amount of monomer. The amount of the redox polymerization initiator system can be equal to any integer value(s) within this range, including the end-points of these ranges.

[0092] The type and amount of the redox polymerization initiator system may be the same or different in the various stages of the multi-stage polymerization.

[0093] Oxidizing agents include, for example, hydrogen peroxide and ammonium or alkali metal persulfates, perborates, peracetates, peroxides, and percarbonates and a water-insoluble oxidizing agent such as, for example, benzoyl peroxide, lauryl peroxide, t-butyl peroxide, t-butyl hydroperoxide, 2,2'-azobisisobutyronitrile, t-amyl hydroperoxide, t-butyl peroxyneodecanoate, and t-butyl peroxypivalate.

[0094] The amount of oxidizing agent may be, for example, from about 0.01 wt% to about 3 wt%, or from about 0.05 wt% to about 2.5 wt%, or from about 0.1 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.15 wt%, or about 0.175 wt%, or about 0.15 wt%, or about 0.3 wt%, or about 0.7 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, orabout 2.75 wt%, and the like based on the total amount of monomer. The amount of the oxidizing agent can be equal to any integer value(s) within this range, including the endpoints of these ranges.

[0095] The type and amount of the oxidizing agent may be the same or different in the various stages of the multi-stage polymerization.

[0096] The free radical polymerization temperature typically is in the range of about 10°C to about 100°C, or in the range of about 15°C to about 95°C, or in the range of about 20°C to about 90°C, or in the range of about 25°C to about 85°C, or in the range of about 30°C to about 80°C, or in the range of about 40°C to about 70°C, or about 12°C, or about 23°C, or about 34°C, or about 45°C, or about 56°C, or about 67°C, or about 78°C, or about 81 °C, or about 92°C, and the like.

[0097] In the case of the persulfate systems, the temperature may be in the range of about 60°C to about 100°C, or in the range of about 65°C to about 90°C, or in the range of about 70°C to about 80°C, or about 62°C, or about 64°C, or about 66°C, or about 68°C, or about 72°C, or about 74°C, or about 75°C, or about 77°C, or about 79°C, or about 81 °C, or about 85°C, or about 88°C, or about 92°C, or about 95°C, or about 98°C, and the like.

[0098] In the redox system, the temperature may be in the range of about 30°C to about 100°C, or in the range of about 30°C to about 90°C, or in the range of about 30°C to about 80°C, or in the range of about 30°C to about 70°C, or in the range of about 30°C to about 60°C, or in the range of about 30° C to about 45° C, or in the range of about 35°C or about 40°C, or about 45°C, or about 50°C, or about 55°C, or about 60°C, or about 65°C, or about 70°C, or about 75°C, or about 80°C, or about 85°C, or about 90°C, and the like. The polymerization temperature can be equal to any integer value(s) within this range,including the end-points of these ranges. The temperature may be the same or different in the various stages of the multi-stage polymerization.

[0099] The pH of the polymerization process ranges from about 2 to about 9, or from about 4.25 to about 8.75, or from about 4.5 to about 8.5, or from about 4.75 to about 8, or from about 5 to about 7.75, or from about 5.25 to about 7.5, or from about 5.5 to about 7, and the like. The pH can be equal to any integer value(s) within this range, including the end-points of these ranges. The pH may be the same or different in the various stages of the multi-stage polymerization.

[0100] One or more nonionic or ionic (e.g., cationic, anionic) emulsifiers, or surfactants, may be used, either alone or together, during either or preferably both polymerization of the first soft phase monomer mixture and polymerization second hard phase monomer mixture in order to emulsify the monomers and / or to keep the resulting polymer particles in dispersed or emulsified form.

[0101] Examples of suitable nonionic emulsifiers include tert-octylphenoxyethylpoly-ethoxyethanol, dodecyloxypolyethoxyethanol, nonylphenoxyethyl-polyethoxyethanol, polyethylene glycol 2000 monooleate, ethoxylated castor oil, fluorinated alkyl esters and alkoxylates, polyoxyethylene sorbitan monolaurate, sucrose monococoate, di(2-butyl)phenoxypolyethoxyethanol, hydroxyethylcellulosepolybutyl acrylate graft copolymer, dimethyl silicone polyalkylene oxide graft copolymer, poly(ethylene oxide)poly(butyl acrylate) block copolymer, block copolymers of propylene oxide and ethylene oxide, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated with 30 moles of ethylene oxide, N-polyoxyethylenelauramide, N lauryl-N-polyoxyethyleneamine and polyethylene glycol dodecyl thioether.

[0102] Examples of suitable ionic emulsifiers include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, potassium stearate, sodium dioctyl sulfosuccinate, sodium dodecyldiphenyloxide disulfonate, nonylphenoxyethylpolyethoxyethyl sulfate ammonium salt, sodium styrene sulfonate, sodium dodecyl allyl sulfosuccinate, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, mixtures of fatty acids (e.g., linseed oil fatty acid), sodium or ammonium salts of phosphate esters of ethoxylated nonylphenol, sodium octoxynol-3-sulfonate, sodium cocoyl sarcocinate, sodium 1-alkoxy-2-hydroxypropyl sulfonate, sodium a-olefin (C14-C16)sulfonate, sulfates of hydroxyalkanols, tetrasodium N-(1,2-dicarboxy ethyl)-N-octadecylsulfosuccinamate, disodium N-octadecylsulfosuccinamate, disodium alkylamido polyethoxy sulfosuccinate, disodium ethoxylated nonylphenol half ester of sulfosuccinic acid and the sodium salt of tert-octylphenoxyethoxypolyethoxyethyl sulfate.

[0103] The one or more emulsifiers or surfactants are generally used in an amount of from about 0.0 wt% to about 3 wt%, or from about 0.05 wt% to about 2.5 wt%, or from about 0.1 wt% to about 2 wt%, or from about 0.5 wt% to about 1.5 wt%, or about 0.025 wt%, or about 0.075 wt%, or about 0.125 wt%, or about 0.15 wt%, or about 0.175 wt%, or about 0.15 wt%, or about 0.3 wt%, or about 0.7 wt%, or about 1.25 wt%, or about 1.75 wt%, or about 2.25 wt%, or about 2.75 wt%, and the like, based on the total amount of monomer. The amount of the one or more emulsifiers or surfactants can be equal to any integer value(s) within this range, including the end-points of these ranges. The type and amount of the oxidizing agent may be the same or different in the various stages of the multistage polymerization. The one or more emulsifiers or surfactants can be added prior to the addition of any monomer charge, during the addition of a monomer charge or acombination thereof. The emulsion and / or at least one intermediate shell and / or at least one outer shell may include or comprise sodium dodecylbenzene sulfonate and optionally other surfactant(s).

[0104] COATING COMPOSITIONS, OTHER ADDITIVES:

[0105] The multi-stage polymeric particles described herein may be used in coating compositions. These coating compositions are especially suitable for decorative coatings. Such coating compositions may be paints, primers, base coats, clear coats and varnishes applied to exterior walls to protect the walls against daily wear and tear. The coating compositions may be topcoat or finish coats that are applied directly to wood, concrete and other common surfaces / substrates of exterior wall coatings. A topcoat or finish coat may be applied on top of the coating composition after the coating composition has been applied to the exterior wall surface / substrate. The topcoat / finish coat can be the same or different from the basecoat or primer.

[0106] These compositions can contain other additives such as are known and used in the art. Non-limiting examples of such additives are opacifiers, pigments, tints, emulsifiers, rheology control additives, driers, etc. The coating formulations, may be modified by the addition of one or more additives, including without limitation additional polymers, metal driers, pigments or colorants, fillers, dispersants or surfactants, plasticizers, defoamers, thickeners, biocides, solvents, rheology modifiers, wetting or spreading agents, leveling agents, conductive additives, thermal insulating filler, adhesion promoters, anti-blocking agents, anti-cratering agents or anti-crawling agents, corrosion inhibitors, anti-static agents, flame retardants, optical brighteners, UV absorbers or other light stabilizers, chelating agents, cross-linking agents, flattening agents, flocculants,humectants, insecticides, lubricants, odorants, oils, waxes or anti-slip aids, soil repellants, and stain resistant agents.

[0107] The coating compositions preferably are those known in the art as low-VOC coatings, i.e. coatings containing low levels of volatile organic components, such as those used to improve the coalescing properties of the coating compositions.

[0108] METHODS OF USING COATING COMPOSITIONS THAT COMPRISE THE MULTI-STAGE POLYMERIC PARTICLES:

[0109] The coating compositions may be applied by conventional techniques, such as dipping, brushing, flowing, or spraying to name a few, onto a variety of substrate surfaces. The substrates may include without limitation, wood, fabricated wood, paper, cardboard, textiles, synthetic resins, ceramics, ferrous metals, non-ferrous metals, stone, concrete, plaster, and the like.

[0110] The coating compositions may be used in an indoor or outdoor application. Outdoor applications may include, without limitation, exterior wall coating, rail car coating, agricultural machinery coating, automobile parts coating, wood coatings, log cabin coatings and deck stains. The polymer composition in the coating composition formed thereof may provide coatings for automotive, industrial, construction and residential housing applications, including for example, without limitation, wood stains, porch and deck stains, glossy top coats, traffic paints, general metal coatings, kitchen cabinetry coatings, automobile refinish, lawn and garden equipment coatings, bus and truck top coatings, gloss trim enamels, metal primers, light duty maintenance coatings, furniture coatings, stain blocking coatings, appliance coatings, dumpster coatings, heavy duty equipment coatings, industrial equipment coatings, paints, primers, base coats, clearcoats and varnishes, topcoat or finish coats, and sash and trim enamels. The coating compositions may also be useful for adhesive and ink applications.

[0111] One embodiment of the invention is directed to a polymer dispersion including a first-formed soft stage and a second-formed hard stage, where the first-formed soft stage comprises a first polymer having a Tg of -50°C to 20°C, a weight average molecular weight of 40,000 to 130,000 and an acid number between 35 mg KOH / g to 70 mg KOH / g, the second-formed hard stage comprises a second polymer having a Tg of 21°C to 100°C, a weight ratio of the first polymer to the total of the first and second polymers is 10% to 90%, and a weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

[0112] Another embodiment is directed to a method for forming a polymer dispersion, wherein the method includes the steps of: feeding a first monomer mixture to a reactor vessel; initiating a free radical polymerization, at a pH of from 2 to 9, of the first monomer mixture to form a first stage of the polymeric particles, the first-formed stage comprising a first polymer comprising the first monomer mixture as polymerized units; feeding a second monomer mixture to the reactor vessel; polymerizing, at a pH of from 2 to 9, the second monomer mixture in the presence of the first-formed stage to form a second stage of the polymeric particles, the second stage including a second polymer comprising the second monomer mixture as polymerized units; where the polymeric particles include the first polymer and the second polymer; the first polymer has a Tg of -50°C to 20°C, a weight average molecular weight of 40,000 to 130,000 and an acid number between 35 mg KOH / g to 70 mg KOH / g; the second polymer has a Tg of 21 °C to 100°C; a weight ratio ofthe first polymer to the total of the first and second polymers is 10% to 90%; and a weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

[0113] In another embodiment, the particles of the method of any of the other embodiments have two separate Tg values as measured by differential scanning calorimetry.

[0114] Another embodiment is directed to a coating composition including: a coalescing agent; and a waterborne emulsion comprising a polymer dispersion according to any of the embodiments described herein, and the coating composition has a volatile organic compound (VOC) content of less than 100 grams per liter of the coating composition and the coating composition has a minimum film forming temperature of less 15°C.

[0115] In another embodiment, the coating composition is a decorative coating composition.

[0116] The first polymer of any of the embodiments includes, as polymerized units based on the dry weight of the first polymer: i) one or more free radical polymerizable ethylenically unsaturated monomers; ii) one or more acid monomers, and iii) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

[0117] The second polymer of any of the embodiments includes, as polymerized units based on the dry weight of the second polymer: iv) one or more free radical polymerizable ethylenically unsaturated monomers, and v) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

[0118] In the polymer dispersions of any of the embodiments, the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are selected from one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

[0119] In the polymer dispersions of any of the embodiments, the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are present in an amount of from about 70 wt% to about 99.99 wt% based on a dry weight of the first polymer.

[0120] In the polymer dispersions of any of the embodiments, the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are present in an amount of from about 80 wt% to about 100 wt% based on a dry weight of the second polymer.

[0121] In the polymeric particles of any of the embodiments, the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are selected from one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

[0122] The polymeric particles of any of the embodiments, includes from Owt% to 10wt% of the iii) free radical polymerizable monomer having a beta dicarbonyl functionality in the first polymer selected from acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, and combinations thereof.

[0123] The polymeric particles of any of the embodiments, includes from 0 to 7 wt% of the v) free radical polymerizable monomer having a beta dicarbonyl functionality in the second polymer selected from acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl(meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, and combinations thereof.

[0124] The principles of the present invention, as well as certain exemplary features and embodiments thereof, will now be described by reference to the following non-limiting examples.

[0125] TEST METHODS:

[0126] GLASS TRANSITION TEMPERATURE:

[0127] The glass transition temperature (Tg) of the polymers are determined by differential scanning calorimetry (DSC) with TA Instruments DSC Q 2000.

[0128] Method: Modulated Standard Method

[0129] A small amount of latex is placed into a standard aluminum DSC pan. The pan is then left to dry at room temperature in a desiccator to remove excess moisture. Once dried, the sample is loaded into the DSC instrument for analysis. The sample is initially cooled to -80°C and held for 5 minutes at that temperature to ensure thermal equilibrium and to stabilize the baseline signal. After stabilization, the sample is heated from -80°C to 120°C without preheating using the following modulated DSC parameters:• Amplitude: ±3°C• Modulation Period: 60 seconds• Underlying Heating Rate: 3°C / min.Throughout the scan, heat flow is continuously recorded with the modulation allowing for the separation of reversible and non-reversible thermal transitions.

[0130] PARTICLE SIZE:

[0131] Particle size and particle size distribution are analyzed with dynamic light scattering using a Nanotrac UPA 150 Particle Size Analyzer and 0.463 µm polystyrene standards.

[0132] BLOCK RESISTANCE:

[0133] Block resistance measurement is recorded on a scale of 0 to 10, where 10 is the best.

[0134] Room Temperature (RT) Block Resistance: The test paints, which include the inventive and comparative polymer dispersions in combination with one or more pigments, are drawn down on a Leneta 3B Opacity chart (available from The Leneta Co., Mahwah, N. J.) using a 3 mil Bird drawdown bar. As used herein, a “mil” refers to one thousandth of an inch or 25.4 microns (pm). The films for room temperature (RT) block resistance are dried in a constant temperature, constant humidity (CT / CH) laboratory at 22°C and 40 to 60 percent relative humidity for 1 day and for 7 days. Two square paint strips of about 1.5 inches square (about 3.8 cm2) are placed together with paint film against paint film under 1 pound (454 grams) of weight in the CT / CH laboratory. After 24 hours, the strips are separated and evaluated according to the ASTM D-4946 (2017) ratings. The test is repeated three times, and the average value is reported.

[0135] Elevated Temperature (ET) Block Resistance: The paint strips are dried in a CT / CH laboratory for 1 day and for 7 days. The paint strips (film against film) are then placed into a 120 degree Fahrenheit (°F) (49°C) oven under 1 pound (454 grams) of weight for one hour for an elevated temperature (ET) block test. The films are allowed to cool at room temperature for 30 minutes before the film separation is recorded.

[0136] SURFACE LEACHING:

[0137] Surface leaching is measured according to ASTM D7190-15, and recorded on a scale of 0 to 5, where 5 is the best.

[0138] The test paints are drawn down on a sealed Leneta chart (available from The Leneta Co., Mahwah, N. J.) using a 3 mil Bird drawdown bar and dried in a constant temperature, constant humidity (CT / CH) laboratory at 22°C and 40-60% relative humidity for 4 days. As used herein, a “mil” refers to one thousandth of an inch, or 25.4 microns (pm).• Three droplets of water are applied to the paint film, and the droplets are allowed to rest for 10 minutes.• The panel is then lifted up vertically and the water droplets are allowed to run down the panel.• The panel is kept in a vertical position and the water marks after drying are rated.

[0139] AMOUNT OF VOC IN COATING COMPOSITIONS:

[0140] Volatile organic compound (VOC) is any volatile compound of carbon, excluding methane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonate, and exempt compounds according to the Environmental Protection Agency and under, for example, 40 Code of Federal Regulations) 51.100(s). The VOC content is measured based on the weight of the VOC per gallon of material without water according to Equation (II), and is reported, for example, as grams VOC per liter (g / L).

[0141] VOC Content=(( Ws-Ww-Wec)) / ((Vm-Vw-Vec)). (II)

[0142] In Equation (II):• VOC Content = grams of volatile organic compounds per liter of coating• Ws = weight of volatiles, in grams• Ww = weight of water, in grams• Wec = weight of exempt compounds, in grams• Vm = volume of coating, in liters• Vw = volume of water, in liters• Vec = volume of exempt compounds, in liters

[0143] MINIMUM FILM FORMING TEMPERATURE (MFFT):

[0144] MFFT was measured according to ASTM D2354-10. The minimum film formation temperature (MFFT) of latexes was analyzed on a rectangular temperature gradient bar. The MFFT was determined at the point where the latex formed a clear and uncracked dry film.

[0145] ADHESION:

[0146] Adhesion was recorded on a visual rating scale of 0-5, with 0 being complete film removal and 5 being 100% film adhesion. Accordingly, 5 is the best adhesion, and an adhesion rating of 4 is acceptable.

[0147] The adhesion of the coating compositions was tested according to ASTM D-3359 (2017), method B (crosshatch adhesion). The coating compositions were applied with a film applicator to unprimed substrate panels with a wet coating thickness of about 3.5 mils (90 microns), resulting in a dry film thickness (DFT) of 1.5 mil (38 microns) + / - 0.1 mil (2.5 microns). The films were dried in a climate-controlled room (50% Relative Humidity and 23°C) for 1 day and 7 days before testing adhesion. The films were scribed with a sharp razor knife in a square grid, with the scoring lines being spaced apart by 2 mm and beingcut through to the substrate. The dry adhesion was tested with the ASTM-specified tape, removing the tape in the manner described in the ASTM. Wet adhesion measurement was conducted by soaking the crosshatch area with a wet paper towel for 20 minutes, blotting the soaked crosshatch area until dry, then allowing recovery for 30 minutes, and then testing the film in the same manner as the dry adhesion test. The adhesion was then visually rated on a scale of 0 to 5.

[0148] KONIG HARDNESS:

[0149] Konig pendulum hardness of coating films was measured following ASTM 4366 (2016). The paint films were prepared on 3 inch x 12 inch (7.6 cm x 30.5 cm) aluminum plates using a 10-mil (254 pm) drawdown bar and allowed to dry for 7 days. The dry film thickness was approximately 4 mils (100 pm). The Konig pendulum resting on the coating surface was set into oscillation (rocking) and the time in seconds for the swing amplitude of the pendulum to decrease from 6 inches (15.2 cm) to 3 inches (7.6 cm) was recorded.

[0150] The Konig hardness is measured in seconds. The results can be in the range of 0-150 second, and a higher number means higher hardness, which is desirable. A Konig hardness for low VOC applications may be in the range of 8-30 seconds.

[0151] GEL CONTENT AND MOLECULAR WEIGHT:

[0152] The dried latex sample was submerged in tetrahydrofuran (THF) for a minimum of 48 hours. The percentage of insoluble fraction was determined gravimetrically. The weight average molecular weight and molecular weight distribution were analyzed using gel permeation chromatography (GPC: Waters 717 Plus with an isocratic 510 pump). Mono-dispersed polystyrene standards with molecular weight ranging from 580 Dalton to 7,500,000 Dalton were used to generate the calibration curve.

[0153] BODY LOTION RESISTANCE

[0154] Latex resins were formulated into semi-gloss paint. The paint was then drawn down onto an aluminum panel with a 3-mil drawdown bar and dried at room temperature for seven days. Body lotion was applied to the dried paint surface using a 3-mil drawdown bar and allowed to sit for 18 hours. The lotion was then carefully removed with tissue paper, ensuring no damage to the paint surface. Konig hardness was measured immediately on both the body lotion-exposed surface and the fresh paint surface.

[0155] EXAMPLES:

[0156] General preparation of multi-stage particles according to the invention:

[0157] The following steps were performed as a multi-stage emulsion polymerization process.• Emulsifier mix was added to reactor and heated to 85°C.• Soft stage monomer mixture was prepared and mixed for 10 min.• Oxidizer / catalyst feed was prepared.• With reactor at 84-86°C, initial monomer feed of a portion of the soft stage monomer mixture was added, and within 5 min, initial oxidizer was added at a temperature of 81 °C-85°C.• After peak of exotherm at around 85°C, the soft stage monomer mixture feed was started.• The oxidizer / catalyst was fed over 240 min.• Simultaneously with the oxidizer / catalyst feeding, the soft stage monomer mixture was fed to the reactor over 76 min. The feed was then stopped for 45 min, and temperature was allowed to drop from 85°C to 80°C gradually during this hold.• Prepared hard stage monomer mixture during the hold period.• The hard stage monomer mixture was then fed over 104 min at a constant temperature of around 80°C.• The resulting polymer composition was cooled to 30°C, and the pH adjusted to 8.0.

[0158] Reaction Components:

[0159] Disponil® FES32 - sodium salts of fatty alcohol ethersulfates with ~4 degree of ethoxylation based on a native C₁₂C₁₄-fatty alcohol (BASF)

[0160] Rhodafac® RS610 - anionic surfactant (Syensqo)

[0161] Comparative Example 1:

[0162] The polymer dispersion of Comparative Example 1 was prepared by adding 2.90 grams of Disponil® FES32, 27.20 grams of Rhodafac® RS610, and 535 grams of water into a three-liter, jacketed-glass reactor equipped with dual impellers, reflux condensers, and stainless-steel feed lines. The reactor was then heated to 80°C. A first monomer mixture (MM1) containing 165 grams of water, 7.49 grams of Disponil® FES32, 8.50 grams of Rhodafac® RS610, 241.09 grams of butyl acrylate (BA), 125.56 grams of methyl methacrylate (MMA), 29.75 grams of diacetone acrylamide (DAAM), and 30.05 grams of methacrylic acid (MAA) was prepared under agitation. 50 grams of MM1 were then fed into the reactor, followed by 0.5 grams of ammonium persulfate and 33 grams of water. After the peak of the exotherm, the rest of MM1 was fed into the reactor within 85 minutes. Separately, 2.0 grams of ammonium persulfate and 134 grams of water were fed into the reactor in 220 minutes. After the MM1 feeding was completed, a second monomer mixture (MM2) (70.41 grams BA, 342.64 grams MMA, and 12.75 grams DAAM) was fedinto the reactor within 95 min. The weight ratio of the first and second polymers was kept at 50:50. After polymerization was complete, 12.50 grams of ammonium hydroxide (14%) were fed into the reactor, and then 21.25 grams of adipic dihydrazide and 108.70 grams of water were added. The emulsion polymer was then collected or stored as an aqueous dispersion or latex.

[0163] Comparative Example 2:

[0164] The polymer dispersion of Comparative Example 2 was prepared using the same procedure as Comparative Example 1, except that 1.06 grams of isooctyl 3-mercaptopropionate (IOMP) were added to MM1.

[0165] Comparative Example 3:

[0166] Comparative Example 3 was prepared using the same procedure as comparative sample 1, except 11.90 grams of IOMP were added to MM1.

[0167] Comparative Example 4:

[0168] Comparative Example 4 was prepared using the same procedure as test sample 4, except the methacrylic acid amount was decreased to 20 grams.

[0169] Comparative Example 5:

[0170] Comparative Example 5 was prepared using the same procedure as Comparative Example 1, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 45%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0171] Comparative Example 6:

[0172] Comparative Example 6 was prepared using the same procedure as Comparative Example 2, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 45%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0173] Comparative Example 7:

[0174] Comparative Example 7 was prepared using the same procedure as Comparative Example 1, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 40%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0175] Comparative Example 8:

[0176] Comparative Example 8 was prepared using the same procedure as Comparative Example 2, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 40%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0177] Example 1:

[0178] Example 1 was prepared using the same procedure as Comparative Example 1, except 2.13 grams of IOMP were added to MM1.

[0179] Example 2:

[0180] Example 2 was prepared using the same procedure as Comparative Example 1, except 4.25 grams of IOMP were added to MM1.

[0181] Example 3:

[0182] Example 3 was prepared using the same procedure as Example 1, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 45%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0183] Example 4:

[0184] Example 4 was prepared using the same procedure as Example 2, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 45%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0185] Example 5:

[0186] Example 5 was prepared using the same procedure as Example 1, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 40%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0187] Example 6:

[0188] Example 6 was prepared using the same procedure as Example 2, with the exception that the first stage polymer weight ratio based on the total weight of the first and second stage polymers was changed from 50% to 40%, and the amount of IOMP added was adjusted accordingly to achieve the weight ratio shown in Table 3.

[0189] The amounts of IOMP in Examples 1-2 and Comparative Examples 1-4 are listed in Table 1 as a weight percentage based on the weight of the first-stage monomer mixture.The total solids content associated with the emulsion polymers is also provided, along with the soft-phase polymer molecular weight and acid number.

[0190] TABLE 1Example Example Comp. Comp. Comp. Comp.1 2 Example Example Example Example 41 2 3IOMP (BOSM) 0.5 1.0 0 0.25 2.8 1.0 Total solids, (%) 45.18 45.28 45.01 45.35 45.27 45.34 Particle size Mv 0.091 0.095 0.087 0.091 0.085 0.106 (micron)Particle size Mn 0.070 0.071 0.068 0.071 0.069 0.086 (micron)Soft phase 98,372 49,606 183,000 177,148 18,648 50,892 molecularweight MwSoft phase acid 46 46 46 46 46 29.5 number (mgKOH / g)PH _ 8.41 8.28 8.13 8.19 8.14 8.00

[0123] The surfactant leaching resistance, block resistance, and scrub resistance properties of the polymer dispersions of Examples 1-2 and Comparative Examples 1-4 are listed in Table 2. The coating compositions of Examples 1-2 and Comparative Examples 1-4 have similar block resistance properties. When the weight average molecular weight of the soft phase polymer is greater than 130,000 g / mol (Comparative Examples 1 and 2), the surfactant leaching resistance rating is 2.5. On the other hand, when the weight average molecular weight of the soft phase polymer is less than 130,000 g / mol (Examples 1-2 and Comparative Example 3), the surfactant leaching resistance rating increased from 2.5 to 3.0 and 4.5, respectively.

[0124] The soft phase polymer acid number can also affect the surfactant leaching results. In Comparative Example 4, although the weight average molecular weight of the softphase polymer is less than 130,000, the surfactant leaching rating is lower than Examples 1 and 2 because the acid number of the soft phase polymer is lower than 35 mg KOH / g (Comparative Example 4). Furthermore, although Comparative Example 3 has good surfactant leaching resistance properties, its scrub resistance property is poor (scrub number <500) because of the high amount of IOMP included in polymer processing.

[0125] TABLE 2Comp. Comp. Comp. Comp. Ex. 1 Ex. 2Ex. 1 Ex. 2 Ex. 3 Ex. 4 4-daySurfactant 3.0 4.0 2.5 2.5 4.5 2.5 leaching1 day RT6.5 6.5 6.5 7.0 7.0 6.5 block7 -day RT8.0 8.0 8.0 8.0 9.5 8.0 block1 day50 °C 6.0 6.0 6.0 6.0 6.0 6.0 block7 day50 °C 7.0 6.5 7.0 7.0 6.0 6.5 blockScrub 1700 840 2988 2100 409 830

[0126] The first soft polymer weight ratio can also influence film formation, thereby affecting the surfactant leaching resistance properties. Decreasing the first soft polymer weight ratio impairs film formation, resulting in poorer surfactant leaching resistance, as shown in Table 3.

[0127] TABLE 3FirstIOMP (% based polymer4-dayon the amount of weight ratiosurfactantthe first stage (% basedleachingpolymer) on totalweight offirst andsecondpolymers)Comp. Ex. 5 0 45 2.5Comp. Ex. 6 0.25 45 2Example 3 0.5 45 3Example 4 1 45 3Comp. Ex. 7 0 40 2Comp. Ex. 8 0.25 40 2Example 5 0.5 40 2.5Example 6 1 40 2.5

[0128] Table 4 shows the comparative Body Lotion Resistance values measured as described herein for coatings including the inventive polymer dispersion of Example 1 (EX) and eight commercially available off-the-shelf paint samples (C1 to C8). Four commercial paints (C4, C6, C7, and C8) exhibit higher Konig hardness values than the coating composition of EX; however, their hardness decreases significantly upon exposure to body lotion. Such a significant decrease in Konig hardness, i.e., change in their performance characteristics would have a detrimental effect on the intended use of these paints. The Konig hardness of three other commercial paints (C2, C3, and C5) does not decrease significantly even after exposure to body lotion because the films are already very soft, as shown by their lower starting Konig hardness values. Commercial paints C1 has similar initial Konig hardness (24 sec) as EX (25 sec), however after body lotion treatment, the Retain % for C1 is only 58% vs 68% for EX. As shown by the results in the Table 4, and represented graphically in the Figure, a coating composition including the polymer dispersion of Example 1 strikes an optimal balance between hardness and body lotion resistance, outperforming the commercial samples in overall performance.

[0129] TABLE 4EX C1 C2 C3 C4 C5 C6 C7 C8 Konig Hardness 25 24 14 16 35 18 32 33 29 (Ki) (untreated, insec.)Konig Hardness 17 14 10 11 19 12 17 12 18 (K2) (body lotiontreated, in sec.)Retain % (= K2 / K1 x 68 58 71 69 54 67 53 36 62100)

[0130] As various modifications could be made in the above methods and compositions and would be apparent to those skilled in the art without departing from the scope of the invention, the disclosures herein are intended to be interpreted as illustrative and not limiting. Any numbers expressing quantities of ingredients, constituents, reaction conditions, and so forth used in the specification are to be interpreted as encompassing the exact numerical values identified herein, as well as being modified in all instances by the term “about” used as a term of approximation, and intended to include minor variations in the literally stated values as understood in the art and subject to any standard deviations found in their respective measurement techniques. None of the features recited herein should be interpreted as invoking 35 U. S C. § 112, paragraph 6, unless the term “means" is explicitly used in reference to a function.

Claims

WE claim:

1. A polymer dispersion comprising a first-formed soft stage and a second-formed hard stage, wherein:the first-formed soft stage comprises a first polymer having a Tg of -50°C to 20°C, a weight average molecular weight of 40,000 to 130,000 and an acid number between 35 mg KOH / g to 70 mg KOH / g;the second-formed hard stage comprises a second polymer having a Tg of 21 °C to 100°C;a weight ratio of the first polymer to the total of the first and second polymers is 10% to 90%; anda weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

2. The polymer dispersion of claim 1, wherein the first polymer comprises, as polymerized units based on the dry weight of the first polymer:i) one or more free radical polymerizable ethylenically unsaturated monomers;ii) one or more acid monomers; andiii) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

3. The polymer dispersion of claim 1 or 2, wherein the second polymer comprises, as polymerized units based on the dry weight of the second polymer:iv) one or more free radical polymerizable ethylenically unsaturated monomers, andv) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

4. The polymeric dispersion of any one of claims 1 -3, wherein the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

5. The polymeric dispersion of any one of claims 1 -4, wherein the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are present in an amount of from about 70 wt% to about 99.99 wt% on a dry weight of the first polymer.

6. The polymeric dispersion of any one of claims 1 -5, wherein the ii) one or more acid monomers in the first polymer are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, linolenic acid, 3-butenoic acid.

7. The polymeric dispersion of any one of claims 1 -6, wherein the ii) one or more acid monomers in the first polymer are present in an amount of from about 0.1 wt% to 20 wt% based on a dry weight of the first polymer.

8. The polymeric dispersion of any one of claims 1 -7, wherein the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

9. The polymeric dispersion of any one of claims 1 -8, wherein the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are present in an amount of from about 80 wt% to about 100 wt% on a dry weight of the second polymer.

10. The polymeric dispersion of any one of claims 1 -9, comprising from about 20 wt% to about 80 wt% of the first polymer and from about 80 wt% to about 20 wt% of the second polymer on a dry weight basis.

11. The polymeric dispersion of any one of claims 1 -10, comprising from 0 to 10 wt% of the iii) free radical polymerizable monomer having a beta dicarbonyl functionality in the first polymer selected from the group consisting of acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, diacetone acrylamide, and combinations thereof.

12. The polymeric dispersion of any one of claims 1-11, comprising from 0 to 7 wt% of the v) free radical polymerizable monomer having a beta dicarbonyl functionality in the second polymer selected from the group consisting of acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, diacetone acrylamide, and combinations thereof.

13. A method for forming a polymeric dispersion, wherein the method comprises the steps of:feeding a first monomer mixture to a reactor vessel;initiating a free radical polymerization, at a pH of from 2 to 9, of the first monomer mixture to form a first stage of the polymeric particles, the first-formed stage comprising a first polymer comprising the first monomer mixture as polymerized units;feeding a second monomer mixture to the reactor vessel;polymerizing, at a pH of from 2 to 9, the second monomer mixture in the presence of the first-formed stage to form a second stage of the polymeric particles, the second stage comprising a second polymer comprising the second monomer mixture as polymerized units;wherein:the polymeric particles comprise the first polymer and the second polymer;the first polymer has a Tg of -50°C to 20°C, a weight average molecular weight of 40,000 to 130,000 and an acid number between 35 mg KOH / g to 70 mg KOH / g; the second polymer has a Tg of 21 °C to 100°C;a weight ratio of the first polymer to the total of the first and second polymers is 10% to 90%; anda weight ratio of the second polymer to the total of the first and second polymers is 90% to 10%.

14. The method of claim 13, wherein the first polymer comprises, as polymerized units based on the dry weight of the first polymer:i) one or more free radical polymerizable ethylenically unsaturated monomers; ii) one or more acid monomers; andiii) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

15. The method of claim 13 or 14, wherein the second polymer comprises, as polymerized units based on the dry weight of the second polymer:iv) one or more free radical polymerizable ethylenically unsaturated monomers, andv) optionally, a free radical polymerizable monomer having a beta dicarbonyl functionality.

16. The method of any one of claims 13-15, wherein the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

17. The method of any one of claims 13-16, wherein the i) one or more free radical polymerizable ethylenically unsaturated monomers in the first polymer are present in an amount of from about 70 wt% to about 99.9 wt% on a dry weight of the first polymer.

18. The method of any one of claims 13-17, wherein the ii) one or more acid monomers in the first polymer are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, linolenic acid, 3-butenoic acid.

19. The method of any one of claims 13-18, wherein the ii) one or more acid monomers in the first polymer are present in an amount of from about 0.1 wt% to 20 wt% based on a dry weight of the first polymer.

20. The method of any one of claims 13-19, wherein the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are selected from the group consisting of one or more alkyl(meth)acrylates, styrene, and mixtures thereof.

21. The method of any one of claims 13-20, wherein the iv) one or more free radical polymerizable ethylenically unsaturated monomers in the second polymer are present in an amount of from about 90 wt% to about 100 wt% on a dry weight of the second polymer.

22. The method of any one of claims 13-21, comprising from about 20 wt% to about 80 wt% of the first polymer and from about 80 wt% to about 20 wt% of the second polymer on a dry weight basis.

23. The method of any one of claims 13-22, comprising from 0 wt% to 10 wt% of the iii) free radical polymerizable monomer having a beta dicarbonyl functionality in the first polymer selected from the group consisting of acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, diacetone acrylamide, and combinations thereof.

24. The method of any one of claims 13-23, comprising from 0 to 7 wt% of the v) free radical polymerizable monomer having a beta dicarbonyl functionality in the second polymer selected from the group consisting of acetoacetoxyalkyl(meth)acrylate, 2-acetoacetoxyethyl (meth)acrylate, 3-acetoacetoxypropyl (meth)acrylate, 4-acetoacetoxybutyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, 3-cyanoacetoxypropyl (meth)acrylate, 4-cyanoacetoxybutyl (meth)acrylate, N-(2-acetoacetoxyethyl) (meth)acrylamide, allyl acetoacetate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetate, diacetone acrylamide, and combinations thereof.

25. A coating composition comprising:a coalescing agent; anda polymer dispersion according to any one of claims 1 -12, wherein the coating composition has a volatile organic compound content of less than 1000 grams per liter of the coating composition and the coating composition has a minimum film forming temperature of less 15°C.

26. The coating composition of claim 25, which is a decorative coating composition.

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