Acrylic emulsions having polymer particles of more than one micron size

Abstract

Disclosed herein are acrylic emulsions having polymeric particles of more than one micron size, as well as methods of synthesizing and using these emulsion compositions.

Description

Technical Field

[0001] The present disclosure relates generally to acrylic emulsions, and more particularly to acrylic emulsions having polymer particles of more than one micron size, and methods of synthesizing and using these emulsion compositions. Background Art

[0002] Water-based coatings, such as latex or emulsion polymer coatings, constitute a significant portion of all coatings used today. Water-based coatings present advantages over conventional oil-based coatings, as they contain fewer undesirable volatile organic solvents and are therefore more environmentally friendly. These polymer products are dispersed in an aqueous medium and are stable under such conditions, but can form a continuous coating film after the water is removed. Summary of the invention

[0003] Disclosed herein are aqueous dispersions of acrylic polymers comprising particles of acrylic polymers dispersed in an aqueous medium, wherein the particles of acrylic polymers have a measured d(0.1) value of 1 μm or greater. In another aspect, provided herein are methods for making aqueous dispersions of acrylic polymers described herein. In some embodiments, the aqueous polymer dispersions are prepared using a free radical emulsion polymerization process. In some embodiments, the free radical emulsion polymerization process is carried out in a dual feed reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0005] Figure 1 A schematic diagram of a dual-feed polymerization reactor used in the synthesis of the acrylic emulsions of the present disclosure is provided. DETAILED DESCRIPTION

[0006] As used herein, the terms "comprising" and variations thereof are used synonymously with the terms "including" and variations thereof, and are open-ended, non-limiting terms. Although the terms "comprising" and "including" are used herein to describe various embodiments, the terms "consisting essentially of" and "consisting of" may be used in place of "comprising" and "including" to provide more specific embodiments, and these terms are also disclosed. As used in this disclosure and the appended claims, the singular forms "a / an", "the" include plural referents unless the context clearly dictates otherwise. Disclosure of percentage ranges and other ranges herein includes disclosure of the endpoints of the range and any integers provided within the range.

[0007] I. Acrylic emulsions having more than one micron-sized polymer particle

[0008] The present disclosure provides acrylic emulsions having polymer particles of more than one micron size, and methods for synthesizing these emulsions. The resulting emulsion polymers exhibit high shelf life stability, which translates to use as standalone polymers or by blending with other co-binders in many coating or adhesive formulations.

[0009] Typical formulations of the emulsions disclosed herein may include copolymers, chain transfer agents, and surfactants. Other ingredients may be added to harden or soften the product. Colorants may also be added. Defoamers may be added.

[0010] The acrylic emulsion of the present invention can be acrylic or styrene-acrylic copolymer. Suitable monomers used in the preparation of the emulsion include, but are not limited to, acrylic acid in an amount of about 0%-2.0% by weight, methacrylic acid in an amount of about 0%-2.0% by weight, styrene in an amount of about 0%-55% by weight, hydroxyethyl methacrylate in an amount of about 0%-5% by weight, butyl acrylate in an amount of about 0%-48% by weight, butyl methacrylate in an amount of about 0%-25% by weight, and styrene in an amount of about 0%-55% by weight, based on the total weight of the composition. %-5% by weight of methyl methacrylate, diacetone acrylamide in an amount of about 0%-5% by weight, methacrylate in an amount of about 0%-15% by weight, ethyl acrylate in an amount of about 0%-15% by weight, glycidyl methacrylate in an amount of about 0%-5% by weight, 2-ethylhexyl acrylate in an amount of about 0%-40% by weight, isobutyl acrylate in an amount of about 0%-10% by weight, and isobutyl methacrylate in an amount of about 0%-10% by weight.

[0011] In certain embodiments, copolymer can be carboxylic acid functional resin.In certain embodiments, carboxylic acid functional resin can be alkali soluble resin.In other words, carboxylic acid functional resin can react with alkaline material to form ionic salt at the carboxylate group of polymer, thereby enhancing the water solubility characteristics of resin.Suitable monomer for preparing carboxylic acid functional resin and low molecular weight copolymer includes monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, acrylic anhydride, methacrylic anhydride, itaconic anhydride, maleic anhydride, fumaric anhydride, crotonic anhydride, styrene, methyl styrene, α-methyl styrene, ethyl styrene, isopropyl styrene, tert-butyl styrene, ethyl methacrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, vinyl acetate, methyl acrylate, open chain conjugated diene, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxymethyl acrylamide, glycidyl acrylate, glycidyl methacrylate, vinyl ester, vinyl chloride, or any two or more mixtures of such monomers. In some embodiments, the carboxylic acid functional carrier resin includes one or more of the following polymerized monomers: ethyl methacrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, vinyl acetate, methyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, or any mixture of two or more such monomers. In one embodiment, the carboxylic acid functional resin includes one or more of the following polymerized monomers: acrylic acid, ethyl methacrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, ethyl acrylate, vinyl acetate, methyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, styrene, methyl styrene, α-methyl styrene, diacetone acrylamide, urea methacrylate, or any mixture of two or more such monomers. In some embodiments, the carboxylic acid functional resin may include a copolymer comprising two or more of styrene, methyl methacrylate, and acrylic acid. In some embodiments, the carboxylic acid functional carrier resin may include a copolymer of acrylic acid and styrene.

[0012] The one or more polymers used in the emulsion may have a glass transition temperature (Tg) of -60°C to 130°C for the individual polymers, or any sub-range or value within the range. For example, any given polymer in the emulsion may have a glass transition temperature (Tg) of -60°C to 100°C, -60°C to 75°C, -60°C to 50°C, -15°C to 50°C, -15°C to 45°C, -15°C to 40°C, -15°C to 35°C, -15°C to 30°C, -15°C to 25°C, -15°C to 20°C, -15°C to 15°C, -15°C to 10°C, -15°C to 5°C, -15°C to 5°C, -15°C to 5°C, -15°C to 60°C, -15°C to 75°C, -15°C to 80°C, -15°C to 90°C, -15°C to 100°C, -15°C to 15 ... 0°C, 0°C to 50°C, 0°C to 45°C, 0°C to 40°C, 0°C to 35°C, 0°C to 30°C, 0°C to 20°C, 0°C to 15°C, 0°C to 10°C, 10°C to 50°C, 10°C to 45°C, 10°C to 40°C, 10°C to 35°C, 10°C to 30°C, 10°C to 25°C, 10°C to 20°C, or any range of Tg including any two of these values ​​as endpoints.

[0013] The emulsion or combination of polymers can have a glass transition temperature (Tg) of -60°C to 130°C for the individual polymers, or any sub-range or value within the range. For example, any given polymer within the emulsion can have a glass transition temperature (Tg) of -60°C to 100°C, -60°C to 75°C, -60°C to 50°C, -15°C to 50°C, -15°C to 45°C, -15°C to 40°C, -15°C to 35°C, -15°C to 30°C, -15°C to 25°C, -15°C to 20°C, -15°C to 15°C, -15°C to 10°C, -15°C to 5°C, -15°C to 5°C, -15°C to 60°C, -15°C to 75°C, -15°C to 80°C, -15°C to 90°C, -15°C to 100°C, -15°C to 15 ... 0°C, 0°C to 50°C, 0°C to 45°C, 0°C to 40°C, 0°C to 35°C, 0°C to 30°C, 0°C to 20°C, 0°C to 15°C, 0°C to 10°C, 10°C to 50°C, 10°C to 45°C, 10°C to 40°C, 10°C to 35°C, 10°C to 30°C, 10°C to 25°C, 10°C to 20°C, or any range of Tg including any two of these values ​​as endpoints.

[0014] These polymers can be formed from emulsion polymerizable monomers. Emulsion polymerizable monomers are known in the art, see, for example, U.S. Patent Nos. 4,820,762; 7,253,218; 7,893,149; and U.S. Patent Publication No. 2015 / 0166803. Emulsion polymerizable monomers can include ethylenically unsaturated monomers. In some embodiments, emulsion polymerizable monomers can include at least one ethylenically unsaturated nonionic monomer. "Nonionic monomer" herein means that the comonomer residue does not carry an ionic charge between pH 1 and 14. Suitable ethylenically unsaturated nonionic monomers include, but are not limited to, (meth)acrylate monomers, including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; (meth)acrylonitrile; (meth)acrylamide; urea-functional monomers; monomers with acetoacetate functionality; styrene and substituted styrenes; butadiene; ethylene, propylene, α-olefins such as 1-decene; vinyl acetate, vinyl butyrate and other vinyl esters; and vinyl monomers such as vinyl chloride and vinylidene chloride.

[0015] The emulsion-polymerizable monomer may include an acrylate monomer, a methacrylate monomer, a styrene monomer, or a mixture of any two or more thereof. In some embodiments, the emulsion-polymerizable monomer does not include a styrene monomer.

[0016] In some embodiments, at least one emulsion polymerizable monomer may be a C1-C4 acrylate, a C1-C4 (meth)acrylate, or a mixture of any two or more thereof. In some embodiments, the emulsion polymerizable monomer may be n-butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, methyl methacrylate, styrene, ethyl acrylate, or a mixture of any two or more thereof.

[0017] In certain embodiments, the polymer of emulsion polymerizable can include one or more ketone functional monomers. Examples of ketone functional monomers include diacetone acrylamide, diacetone methacrylamide, diacetone acrylate, diacetone methacrylate, (methyl) acetoacetoxymethyl acrylate, (methyl) 2-(acetoacetoxy)ethyl acrylate, (methyl) 2-acetoacetoxypropyl acrylate, butanediol-1,4-acrylate-acetoacetate, vinyl methyl ketone, vinyl ethyl ketone, and vinyl isobutyl ketone, allyl acetoacetate, vinyl acetoacetate, or vinyl acetoacetamide. In one embodiment, the polymer of emulsion polymerizable includes repeating units derived from diacetone acrylamide.

[0018] The emulsion can be formed by an emulsion polymerization reaction, which can involve at least one emulsion polymerizable monomer, a low molecular weight copolymer, and other ingredients and / or reagents (such as an initiator). In some embodiments, the emulsion polymerization occurs in a dual feed reactor.

[0019] Initiator can be a water-soluble compound that is easy to mix and blend with emulsion. Non-limiting examples of water-soluble initiators for emulsion polymerization include ammonium salts and alkali metal salts of peroxodisulfuric acid, such as sodium peroxodisulfate, hydrogen peroxide or organic peroxides, such as tert-butyl hydroperoxide. Initiator can be a thermal initiator. Suitable initiators include but are not limited to 2,2'-azobis(2-methylpropionamidine) dihydrochloride, ammonium persulfate, sodium persulfate and potassium persulfate. Also suitable is a reduction-oxidation (redox) initiator system. The redox initiator system is composed of at least one generally inorganic reducing agent and an organic or inorganic oxidizing agent. The oxidizing component includes, for example, the emulsion polymerization initiator determined above. The reducing component includes, for example, an alkali metal salt of sulfurous acid, such as sodium sulfite, sodium bisulfite, an alkali metal salt of disulfurous acid such as sodium bisulfite, a bisulfite addition compound with aliphatic aldehydes and ketones such as acetone bisulfite, or a reducing agent such as hydroxymethanesulfinic acid and its salt, or ascorbic acid. Redox initiator systems can be used with soluble metal compounds, the metal components of which can exist in multiple valence states. Typical redox initiator systems are, for example, ascorbic acid / iron sulfate (II) / sodium peroxodisulfate, tert-butyl hydroperoxide / sodium disulfite, tert-butyl hydroperoxide / hydroxymethanesulfinic acid Na. These individual components (e.g., reducing components) can also be mixtures, an example being a mixture of the sodium salt of hydroxymethanesulfinic acid and sodium disulfite. The compound is usually used in the form of an aqueous solution, wherein the lower limit concentration is determined by the amount of acceptable water in the dispersion, and the upper limit concentration is determined by the solubility of the corresponding compound in water. In general, the concentration is 0.1% to 30% by weight based on the solution, preferably 0.5% to 20% by weight, more preferably 1.0% to 10% by weight. The amount of initiator is usually 0.1% to 10% by weight based on the monomer to be polymerized, preferably 0.5% to 5% by weight. It is also possible to use two or more different initiators in emulsion polymerization.

[0020] In some embodiments, the initiator can be ammonium persulfate and the oxidant can be tert-butyl hydroperoxide. In this case, the weight ratio between ammonium persulfate and tert-butyl hydroperoxide can range from 40:1 to 2:1 or 30:1 to 4:1 or any sub-range or value within these ranges.

[0021] In certain embodiments, the emulsion comprises one or more chain transfer agents to control molecular weight, branching and / or gel formation.Exemplary chain transfer agents include but are not limited to isooctyl mercaptopropionate (IOMPA), butyl mercaptopropionate, 2-ethylhexyl mercaptopropionate, tert-dodecyl mercaptan, and thioglycerol.

[0022] Generally, the amount of chain transfer agent employed may vary from 0.01 to 1% by weight, based on the total amount of monomers to be polymerized.

[0023] The polymer emulsions described herein may also contain surfactants. In some embodiments, the surfactant is anionic or nonionic. In some embodiments, the surfactant contains one or more fatty alcohol alkoxylates. In other embodiments, one or more fatty alcohol alkoxylates are fatty alcohol ethoxylates, fatty alcohol propoxylates, or any combination thereof. In some embodiments, the surfactant contains one or more ethylene oxide / propylene oxide block copolymers. In some embodiments, the surfactant contains one or more fatty alcohol ethoxylates. In some embodiments, the surfactant contains one or more alkyl sulfosuccinate ethoxylates. In some embodiments, the surfactant contains one or more fatty alcohols (having an alkyl chain length of about 12 to about 18 carbons; and a degree of ethoxylation of about 10 to about 80 moles of ethylene oxide units). In some embodiments, the surfactant includes a nonionic surfactant. In some embodiments, the surfactant includes an anionic surfactant. In some embodiments, the anionic surfactant includes one or more alkyl sulfonates, alkylbenzene sulfonates, alkyl sulfates, alkylbenzene sulfates, phosphates, phosphinates, fatty carboxylates, or any combination of two or more thereof.

[0024] Typically, the amount of surfactant employed may vary from 0.3 to 1% by weight, based on the total amount of monomers to be polymerized.

[0025] The polymer compositions described herein may contain other materials such as, but not limited to, other aqueous resin solutions, rheology modifiers, wetting agents, defoamers, thickeners, stabilizers, buffers, salts, preservatives, flame retardants, biocides, corrosion inhibitors, crosslinking agents, lubricants, colorants, dyes, waxes, fragrances, and fillers.

[0026] As described herein, the acrylic or styrene-acrylic latex dispersion particles can have d(0.1) of 0.1 μm or greater, 0.5 μm or greater, or 1 μm or greater. Large and multimodal particle size distributions are aided by the lack of micelles caused by injecting monomer and seed polymer into the reactor during the initial stages of polymerization. Additionally, ramp-up and ramp-down power feeding of surfactant and monomer promotes large and multimodal particle sizes.

[0027] II. Method for producing emulsion

[0028] The emulsions disclosed herein can be formed by emulsion polymerization, which relies on the use of small molecule surfactants containing polar / hydrophilic groups and non-polar / hydrophobic groups. The amphiphilic nature of these materials allows them to effectively stabilize heterogeneous solutions (i.e., polymer particles in water). The emulsion polymerization reactions disclosed herein can be carried out in dual feed reactors (e.g., Figure 1 The reactor can be equipped with a water bath, a mechanical stirrer, a temperature control probe, a feed tube for monomer addition, a feed tube for initiator addition, and a reflux condenser. Typically, each tank is filled with the following contents listed in Table 1.

[0029] Table 1. Figure 1 The charging of the different vessels in the dual-feed reactor is depicted in .

[0030]

[0031] Initially, DI water was charged to the reactor 14, which was then heated to 85°C. Acid monomer at 80°C was added to the reactor 14 in one shot, followed by the addition of an initial initiator shot from tank 10 pumped into the reactor 14 via pump 20. Then, a pre-emulsion feed containing DI water, surfactant, monomer A, and optionally a chain transfer agent in tank 12 was pumped by pump 18 to feed into the reactor 14. At the same time, a pure monomer feed containing monomer A in tank 16 was pumped into the reactor 14 by pump 22. After 15 minutes of pre-emulsion, a second charge of the initiator feed from tank 10 was pumped into the reactor 14. The total feed time was three hours. At the end of the pre-emulsion, the pure monomer feed and the initiator feed kept the reactor at 85°C for 30 minutes, and then rinse water was added to reduce the temperature to 70°C. After the chemical stripping process was completed, the reactor 14 was cooled to room temperature, and then the polymer finished polymer was filtered into a storage container.

[0032] As described herein, the free radical initiator can be a water-soluble initiator. Examples of such water-soluble initiators can include, but are not limited to, persulfates such as sodium persulfate (Na2S2O8) and potassium persulfate; peroxides such as hydrogen peroxide and tert-butyl hydroperoxide (t-BHP); and azo compounds such as VAZO commercially available from Chemours Company. TM Initiators. They can be used alone or in combination with one or more reducing agents or activators (e.g., bisulfite, metabisulfite, ascorbic acid, isoascorbic acid, sodium formaldehyde sulfoxylate, ferrous sulfate, ammonium ferrous sulfate, and ethylenediaminetetraacetic acid iron).

[0033] Typically, the amount of free radical initiator employed may vary from 0.1 to 1% by weight, based on the total amount of monomers to be polymerized.

[0034] The coating formulations described herein can be used to prepare products including coatings, adhesives, and the like.

[0035] The following examples are intended to further illustrate certain aspects of the methods and compositions described herein and are not intended to limit the scope of the claims.

[0036] Examples

[0037] The following examples are presented to provide a person of ordinary skill in the art with a complete disclosure and description of how to make and evaluate the compositions and / or methods claimed herein, and are intended to be exemplary only and are not intended to limit the scope of the present disclosure. Unless otherwise indicated, parts are parts by weight, temperatures are in ° C. or at ambient temperature, and pressures are equal to or close to atmospheric pressure.

[0038] The particle size distribution percentiles are represented by the letter "d" followed by the % value. Thus, d(0.1) or d10 = 1.107 uM, d(0.5) or d(50) = 3.79 uM and d(0.9) or d(90) = 7.094 uM means that 10% of the sample is less than 1.107 uM, 50% of the sample is less than 3.79 uM and 90% of the sample is less than 7.094 uM.

[0039] Example 1: Synthesis of acrylic emulsion

[0040] Initially, the polymerization reactor was charged with the required amount of DI water, about 25% of the total surfactant amount, and seed polymer. The reactor was heated to 85°C, and 80°C of acid monomer was added at once. Then the initial initiator injection amount (about 25% of the total initiator solution) was added immediately at 85°C. After the initiator injection amount, the pre-emulsion feed and the pure monomer feed were started at the same time. After 15 minutes of pre-emulsion feed and pure monomer feed, the second charge of the initiator feed was started. The total feed (pure monomer+pre-emulsion+initiator) time was 3 hours. At the end of the pre-emulsion, the pure monomer and initiator feeds maintained the reactor at 85°C for 30 minutes, and then rinse water was added to reduce the reactor temperature to 70°C. At 70°C, delayed oxidant and reductant feeds were started to reduce residual monomers. After the chemical stripping process was completed, the reaction was cooled to room temperature. Finally, the post-addition solution was added, and the reactor mixed contents for 15 minutes, and then the polymer was filtered in a storage container.

[0041] Table 2. List of acrylic emulsion formulations.

[0042]

[0043] Table 3. Malvern particle size distribution of formulations 1-14.

[0044]

Claims

1. A polymer emulsion composition comprising at least one block copolymer; At least one chain transfer agent At least one surfactant The particles of the acrylic polymer have a measured d(0.1) value of 1 μm or greater.

2. The polymer emulsion according to claim 1, wherein The emulsion composition has a glass transition temperature of -60°C to 130°C.

3. The polymer emulsion according to claim 1, wherein The copolymer is an acrylic or a styrene-acrylic copolymer.

4. The polymer emulsion composition according to claim 1, wherein The polymer contains the functional monomers acrylic acid, methacrylic acid, styrene, α-methylstyrene, hydroxyethyl methacrylate, esters of acrylic acid or methacrylic acid.

5. The polymer emulsion according to claim 1, wherein The chain transfer agent is present in an amount of 0.01 wt. % to 1 wt. % based on the total weight of the composition.

6. The polymer emulsion according to claim 1, wherein The chain transfer agent is selected from the group consisting of isooctyl mercaptopropionate (IOMPA), butyl mercaptopropionate, 2-ethylhexyl mercaptopropionate, tert-dodecyl mercaptan, and thioglycerol.

7. The polymer emulsion according to claim 1, wherein The surfactant is present in an amount of 0.3 wt. % to 1 wt. % based on the total weight of the composition.

8. The polymer emulsion according to claim 1, wherein The surfactant is selected from the group consisting of fatty alcohol alkoxylates, fatty alcohol ethoxylates, ethylene oxide block copolymers, propylene oxide block copolymers, alkyl sulfonates, alkyl benzene sulfonates, alkyl sulfates, alkyl benzene sulfates, phosphates, phosphinates, or fatty carboxylates.

9. The polymer emulsion according to claim 1, wherein The emulsion further comprises an aqueous resin solution, a rheology modifier, a wetting agent, a defoamer, a thickener, a stabilizer, a buffer, a salt, a preservative, a flame retardant, a biocide, a corrosion inhibitor, a crosslinking agent, a lubricant, a colorant, a dye, a wax, a fragrance, or a filler.

10. A method for producing the polymer emulsion according to claim 1 in a dual feed reactor, the method comprising (i) charging DI water, surfactant, and seed polymer into a polymerization reactor; (ii) adding an initiator to the reactor; (iii) feeding monomers from two separate tanks into the reactor to form a polymer composition; (iv) adding rinse water to the reactor; (v) chemically stripping the polymer composition; and (vi) filtering the polymer composition into a storage container.

11. The method of claim 10, wherein: The monomer feed was gradually increased and decreased.

12. The method of claim 10, wherein: The dual-power feed synthesis process produces gradient molecular weight polymer chains.

13. The method of claim 10, wherein: The dual power feed synthesis process produces a broad Tg of the resulting polymer dispersion.

14. The method of claim 10, wherein: The dual-power feed synthesis process produces a gradient Tg.

15. A substrate coated with the composition of claim 1.

16. An adhesive comprising the composition according to claim 1.

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