Fast drying aqueous amine free coating composition(s)

Abstract

Coating compositions and methods providing a high build, fast drying, fast hardening non-amine containing aqueous latex binders are provided, wherein the coating composition is applied to a substrate at a wet film thickness to about 15 mils that ensure drying times of less than 10 minutes. The binder requires the use of at least one specific coalescent solvent with both anionic and non-anionic surfactants.

Claims

1. An amine free aqueous coating composition comprising: an amine free latex binder; and only one coalescing solvent, wherein the amine free latex binder comprises at least one anionic surfactant, a non-ionic surfactant, and a polymer prepared from at least one hard monomer, at least one soft monomer, and at least one acid functional monomer, the amounts of the monomers and the anionic surfactant being: (i) 35 to 65% by weight of the at least one hard monomer, based on a total weight of said latex binder; (ii) 25 to 55% by weight of the at least one soft monomer, based on the total weight of said latex binder weight; (iii) 0.5 to 15% by weight of the at least one acid functional monomer, based on the total weight of said latex binder weight; and (iv) 0.1% to 4% by weight of the at least one anionic surfactant, based on the total weight of said latex binder weight; wherein said latex binder has a glass transition temperature less than 45 degrees Centigrade, and wherein said latex binder is amine free, ammonia free, and ammonium hydroxide free, and has an average particle size diameter consisting of between 210 nanometers and 290 nanometers, and wherein said coating composition exhibits a drying time of less than 10 minutes as measured by ASTM test method D711-2010.

2. The composition of claim 1, wherein the glass transition temperature of the latex binder is between 23 degrees Centigrade and 36 degrees Centigrade.

3. The composition of claim 1, wherein said composition is operable to be dried at ambient temperature when the composition is applied to a surface at or above 15 mils film thickness.

4. The composition of claim 1, wherein the coalescing solvent is selected from the group consisting of: propyl glycol n-propyl ether, propylene glycol methyl ether, dipropyl glycol methyl ether, ethylene glycol monopropyl ether, dipropylene glycol monobutyl ether, propylene glycol, diethylene glycol monobutyl ether, trimethyl pentanediol monoisobutyrate, and methanol.

5. The coating composition of claim 1, wherein said hard monomer comprises a methacrylic monomer.

6. The coating composition of claim 1, wherein said soft monomer comprises butyl acrylate.

7. The composition of claim 1, wherein the at least one acid functional monomer is present in an amount between 2.5 and 3.1 weight percent, based on the total weight of said latex binder weight, and the latex binder has an acid number of 17.

8. The composition of claim 1, wherein said latex binder has an average particle size diameter consisting of between 250 nanometers and 290 nanometers.

9. An amine free aqueous coating composition comprising: only one coalescing solvent; and an amine free latex binder comprising a surfactant and a polymer prepared from at least one hard monomer, at least one soft monomer, and at least one acid functional monomer, the amounts of the monomers and the surfactant being: (i) 35 to 65% by weight of the at least one hard monomer, based on a total weight of said latex binder; (ii) 25 to 55% by weight of the at least one soft monomer, based on the total weight of said latex binder; (iii) 0.5 to 15% by weight of the at least one acid functional monomer, based on the total weight of said latex binder; (iv) 1 to 10% by active weight of the surfactant, based on the total weight of said latex binder, wherein the surfactant comprises at least one non-ionic surfactant and at least one anionic surfactant; wherein the coating composition is substantially free of amine, ammonia, and ammonium hydroxide, and wherein the coating composition has a drying time of less than 10 minutes as measured by ASTM test method D711-2010.

10. The composition of claim 9, wherein the latex binder has a glass transition temperature less than 45 degrees Centigrade.

11. The composition of claim 9, wherein the latex binder has a glass transition temperature of between 23 degrees Centigrade and 36 degrees Centigrade.

12. The composition of claim 9, wherein the coating composition comprises particles having an average particle size diameter of between 210 nanometers and 290 nanometers.

13. The composition of claim 9, wherein at least one acid functional monomer is present in an amount between 2.5 and 3.1 weight percent, based on the total weight of latex binder.

14. The composition of claim 9, wherein said coating composition is operable to be dried at ambient temperature when the composition is applied to a surface at or above 15 mils film thickness.

15. The composition of claim 9, wherein the latex binder has an acid number of 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The high build fast hardening coating compositions of this invention as applied to a substrate at a wet film thickness of about 15 mils, have very rapid dry times, lower film formation temperatures, higher moisture resistance, higher crack resistance, and high solids content and hardness in the applied dried paints. One of the aspects to obtaining the excellent characteristics lies in the combination of the aqueous latex binder of this invention with the proper coalescing solvent(s) as well as the proper use of both anionic and non-anionic surfactants with appropriate characteristics and in proper concentrations. Heretofore, it has not been possible to employ 15 mil films with drying times of less 10 minutes at 20 C or above without the use of amines in the binder formulation.

(2) In accordance with this invention, the coating composition comprises a latex binder comprising at least one hard monomer, at least one soft monomer, and an acid functional monomer. The latex binder comprises about 35 to about 65 weight percent hard monomer, about 25 to about 55 weight percent soft monomer, about 0.5 to about 12 weight percent acid functional monomer, and about 1.0 to about 10.0 active weight percent of the total combination of the non-anionic and anionic surfactant, all based on the total weight percent of the latex binder.

(3) With respect to the hard monomer, the term “hard monomer” generally means a monomer whose homopolymer has a glass transition temperature (Tg) of greater than 30° C. and includes, but is not limited to non-functional methacrylic monomers such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, and mixtures thereof and alkenyl aromatic monomers such as styrene, p-methyl styrene, methyl styrene, o-methyl styrene, o,p-dimethyl styrene, o,p-diethyl styrene, p-chlorostyrene, o-methyl-p-isopropyl styrene, o,p-dichlorostyrene, isopropyl styrene, t-butyl styrene, and mixtures thereof.

(4) The preferred hard monomer is methyl methacrylate.

(5) The term “soft monomer” generally means a monomer whose homopolymer has a Tg of less than about −20° C., and includes nonfunctional acrylic monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, ethyl hexyl acrylate, isodecyl methacrylate, lauryl methacrylate, tridecylmethacrylate, and mixtures thereof. The preferred soft monomer is butyl acrylate.

(6) The polymerization of these monomers can optionally include other ethylenically unsaturated copolymerizable comonomers. Also, optionally, the polymerization may be in the presence of other crosslinking monomers.

(7) Surfactants useful in the present invention are both anionic surfactants and non-ionic surfactants. Anionic surfactants include, but are not limited to, alkylphenolethoxylate sulfates and sulfonates, alkysulfates and sulfonates, such as ammonium lauryl ether sulfate, alkali alkylether sulfates such as sodium lauryl ether sulfate, octyl phenol ethoxylates, sodium lauryl sulfate, phosphate esters, and mixtures thereof. Non-anionic surfactants include for example; octyl phenol ethoxylate, alkyl ethylene oxide/propylene oxide copolymers. Generally, the emulsion comprises weight percent anionic surfactant and 0.5 to 1.5 active weight percent of the non- about 0.5 to 2.5 active anionic surfactant based on the weight of the monomer. Preferably, the range of the total non-anionic and anionic surfactant is between 4 and 17 weight percent. As used herein, the “weight percent surfactant” is defined as the total dry weight of the surfactant(s) used in making the polymer emulsion divided by the total weight of the monomers used in making the polymer.

(8) The latex binder of the invention has a Tg of less than 45° C. and an average particle size of between 210 nanometers to 290 nanometers. The solids content of the latex binder is generally at least about 40 weight percent, preferably within the range of about 45 to about 60 weight percent, and more preferably within the range of 45 to about 55 weight percent.

(9) At least one coalescing solvent is added to the latex binder. Aqueous latex paints cure by a process known as coalescence where first the water, and then the trace, or coalescing, solvent, evaporate and draw together and soften the binder particles and fuse them together into irreversibly bound networked structures, so that the paint will not redissolve in the solvent/water that originally carried it. The solvent can be selected by one skilled in the art based on desired minimum film formation temperature, dry time and desired water resistance, or other desired characteristics of the final paint composition. Some examples of coalescing solvents include alkyl alcohol ethoxylates such as propyl glycol n-propyl ether (PnP), propylene glycol methyl ether (PM), dipropylene glycol methyl ether (DPM), ethylene glycol monopropyl ether (EP), dipropylene glycol monobutyl ether (DPnB), propylene glycol (PG), diethylene glycol monobutyl ether (butyl carbitol), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (commercially available as Eastastripe from Eastman Chemical, Eastman, Tenn.), and methanol. Of the various coalescing solvents that can be used, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, which possesses a high film integrity at low levels, enhances a lower temperature of formation and scrub resistance and is not classified as a VOC, and has been found to provide low toxicity and the required solvent of choice for these formulations

(10) The emulsion polymers described are prepared in the form of aqueous dispersions in a conventional manner by emulsion polymerization in an aqueous medium in the presence of a free radical oxygen-containing initiator in which the monomers are mixed with the surfactants prior to being fed into the reaction vessel. The latex binders may also be prepared by other conventional methods such as simultaneous feed of the monomer mixture and surfactant mixture into the reactor and by the core/shell method.

(11) It is preferred to add an initiator to the polymer emulsion composition. Exemplary initiators include, but are not limited to, t-butyl hydroperoxide, sodium persulfate, ammonium persulfate, hydrogen peroxide, and mixtures thereof. Particular suitability for preparing finely divided dispersions are alkali metal salts or ammonium salts such as sodium carbonate or ammonium persulfate, which in general is used in amounts of about 0.25 to 1% by weight based on the total weight of binder.

(12) A final coating paint formulation typically also comprises a dispersing aid, thickening aids, a biocide, pigments, extenders and fillers, and a defoamer as shown in Tables 5 and 6.

(13) A lower acid level is desirable for decreased water sensitivity of the final coating. While not intending to be bound to any theory, a lower acid number for the coating composition may help control the latex particle size, stability, water solubility and Tg. For traffic paints, in particular, a lower acid number can be advantageous on the heat age stability, freeze/thaw stability, dry time and scrub resistance. The high build aqueous coating compositions can be applied to surfaces of high traffic areas at high film thicknesses, normally 2 to 15 mils wet film thickness, and allowed to dry at ambient conditions. Typically, the dry film thickness of coatings of this invention is about 15 mils which represents a significant improvement over any previously known compositions in that that the drying time of these high build paints is reduced to below 10 minutes without the use of amines in the binder formulation and durability is not sacrificed. In the binder formulations of present invention there is no need for adjusting the pH using ammonia or ammonium hydroxide because there are no polyamine interactions with the anionic surfactants (that are used to stabilize the emulsion). Polyfunctional amines require full deprotonization to ensure no reaction with the anionically stabilized (binder) polymer emulsion and anionic ingredients in the final paint formulation. In the case of the present invention, because there are no functional amine groups added to the binder (latex emulstion), the requirements for deprotonization described above are unnecessary, however shelf life as well as fast dry times have not been compromised of the final paint (coating) formulations.

(14) The coating formulations of this invention have a fast dry time, fast hardening and early water resistance and produce crack-free coating films. The resulting coating has improved dirt resistance and release, and is highly suitable for use as a fast dry coating for floors and other high traffic hard surfaces such as concrete, masonry, stone, brick. In addition, the surfaces can be smooth, rough, and/or porous, and upon drying, the coating composition forms a smooth film. The novel latex paint and binder formulations described herein have coalescing solvent loading between 1.7% and 2.5%, and with Tg's between 23 and 36 degrees Centigrade for the dry latex.

EXAMPLES

(15) The following examples demonstrate the preparation of exemplary latex binders within the scope of the invention, as well as paint compositions formulated using these latex binders. Unless otherwise stated, “percent” means percent-by-weight.

(16) As used herein, the following abbreviations and terms have the following meanings

(17) IGEPAC CA407, octylphenenol ethoxylate, received from Rhodia.

(18) Stepan-Mild SL3-BA, disodium laureth sulfosuccinate, received from Stepan.

(19) Aerosol A102, disodium ethoxylated alcohol half ester of sulfosucnic acid, received from Cytec.

(20) SDS, sodium dodecyl sulfate, purchased from Aldrich.

(21) Tamol 901, Anionic polyelectrolyte/polyacid pigment dispersant, available from XXXX

(22) Surfynol CT-136, acetylenic diol anionic surfactant blend, available from Air Products Corp., Allentown, Pa.

(23) Drewplus L-493, contain methylated silica and silica colloidal amorphous (Ashland Chemical)

(24) Ti-Pure R-900, Titanium Dioxide (TiO2), available from DuPont

(25) Omyacarb-5, Calcium carbonate, available from Omya North America

(26) Natrosol 250HR (2% aqueous), a Water soluble cellulose, 2-hydroxyethylether, available from Ashland, Inc.

(27) Bayferrox 3950, an inorganic pigment, available from Bayferrox.

Example A

Preparation of 35° C. Tg Latex Binder Formulation

(28) The monomer mixture of butyl acrylate (BA), methyl methacrylate (MMA), and methacrylic acid (MAA), as shown below in Table 1 was slowly added into a flask containing a stirring water solution of NaHCO.sub.3, Aerosol A-102, CA407, and deionized water to obtain a monomer pre-emulsion. An initiator solution was prepared by dissolving ammonium persulfate (3.52 g) in deionized water (160 g). The monomer pre-emulsion (128 g) and initiator solution (64.8 g) were charged into the reaction flask with NaHCO.sub.3 (0.5 g) and Aerosol A-102 (1.4 g). The contents were stirred for 0.5 h at 80° C. bath temperature to form seed latex particles. The remaining pre-emulsion mixture and initiator were concurrently added into the seed latex at a constant rate over a period of 3 h. The polymerization was maintained at 80° C. under nitrogen. After the addition of all ingredients, the contents were heated at 80° C. for an additional 2 h in order to digest all the residual monomers. The latex was then filtered through a 300 mesh screen to remove any residual coagulum.

(29) The glass transition temperature of the latex binder is 35° C. Tg. Based on the formulations, the high and low carboxyl functional latex have theoretical acid number around 17 and 5, respectively, and the carboxyl functional monomer percentage in all the monomers around 4.5% and 1.3%, respectively.

(30) TABLE-US-00001 TABLE 1 Components Function Weight, g BA Monomer 210 MMA Monomer 250 MAA Carboxyl monomer 23 NaHCO.sub.3 Buffer 0.5 Aerosol A-102, Surfactant 17 31% active IGEPAL CA-407, Surfactant 4.3 70% active Water Solvent 257

Example B

Preparation of 23° C. Tg Latex Binder Formulation

(31) The monomer mixture of BA, MMA, and MAA, as shown below in Table 2 was slowly added into a flask containing a stirring water solution of NaHCO.sub.3, Stepan SL3-BA, CA407, and deionized water to obtain a monomer pre-emulsion. An initiator solution was prepared by dissolving ammonium persulfate (3.52 g) in deionized water (160 g). The monomer pre-emulsion (128 g) and initiator solution (64.8 g) were charged into the reaction flask with NaHCO.sub.3 (0.5 g) and Stepan SL3-BA (1.4 g). The contents were stirred for 0.5 h at 80° C. bath temperature to form seed latex particles. The remaining pre-emulsion mixture and initiator were concurrently added into the seed latex at a constant rate over a period of 3 h. The polymerization was maintained at 80° C. under nitrogen. After the addition of all ingredients, the contents were heated at 80° C. for an additional 2 h in order to digest all the residual monomers. The latex was then filtered through a 300-mesh screen to remove any residual coagulum.

(32) TABLE-US-00002 TABLE 2 Components Function Weight, g BA Monomer 210 MMA Monomer 250 MAA Carboxyl monomer 23 NaHCO.sub.3 Buffer 0.5 Stepan SL3-BA, Surfactant 17 30% active IGEPAL CA-407, Surfactant 4.3 70% Water Solvent 257

Example C

Preparation of 29° C. Tg Latex Binder

(33) The monomer mixture of BA, MMA, and MAA, as shown below in Table 4 was slowly added into a flask containing a stirring water solution of NaHCO.sub.3, SDS, CA407, and deionized water to obtain a monomer pre-emulsion. An initiator solution was prepared by dissolving ammonium persulfate (3.52 g) in deionized water (160 g). The monomer pre-emulsion (128 g) and initiator solution (64.8 g) were charged into the reaction flask with NaHCO.sub.3 (0.8 g) and SDS (2.8 g). The contents were stirred for 0.5 h at 80° C. bath temperature to form seed latex particles. The remaining pre-emulsion mixture and initiator were concurrently added into the seed latex at a constant rate over a period of 3 h, and then 50 g water was added. The polymerization was maintained at 80° C. under nitrogen. After the addition of all ingredients, the contents were heated at 80° C. for an additional 2 h in order to digest all the residual monomers. The latex was then filtered through a 300-mesh screen to remove any residual coagulum.

(34) TABLE-US-00003 TABLE 3 Components Function Weight, g BA Monomer 315.9 MMA Monomer 379 MAA Carboxyl monomer 9 NaHCO.sub.3 Buffer 0.8 SDS, 14% active Surfactant 102.4 CA-407, 70% Surfactant 12.8 active Deionized water Solvent 400

(35) Table 4 below summarizes the characteristics of the binder composition in use with the final waterborne coating formulation (paint). This also lists the coalescent solvent to be used for the coating. The dryer times are significantly lower than those of conventional binders and coatings that contain polyfunctional amines. The concentration for the surfactants in the examples provided (A-C in Tables 1, 2, and 3) varies from 14% (SDS) to 70% (CA407), and surfactant with same chemical structure can have different concentrations. For example, SDS generally has been commonly used in several concentrations, such as 22, 28, and 50%. To better define surfactant efficiency, “active” weight percentage is often used to define surfactant concentration.

(36) TABLE-US-00004 TABLE 4 Example A Example B Example C Tg of Emulsion 35.3° C. 23.3° C. 29° C. Total  Weight 927.22 g 927.22 g 1387.0 g Hard Monomer Wt % 27.0% 27.0% 27.3% Soft Monomer Wt % 22.6% 22.6% 22.8% Carboxyl Monomer 2.48% 2.48% 0.65% Wt % Anionic Surfactant  1.1%  1.1%    2.0 (active Wt % of monomer weight) Nonionic Surfactant  0.6%  0.6%  1.3% (active Wt % of monomer weight) Total active Surfactant  1.7%  1.7%  3.3% Wt % Particle Size (nm) 283 215 253 MFFT   16° C.   8° C. 15° C. Coalescent solvent Eastastripe Eastastripe Eastastripe Dry Time 6.5 min 7.5 min 9 min

Formulation of Coatings

(37) The latex binders of Examples A through C have been formulated into each of the waterborne fast dry coating compositions according to the paint formulas which are presented in Tables 5 and 6. The solvents for the use of these fast drying amine free compositions are subject to change as drying times required may also change over time. Tables 5 and 6 provide final finished white and yellow coating (paint) formulations using the amine free binder compositions of the present invention and themselves represent novel and unique coatings used primarily for road surfaces. The binder in the coatings (paint) formulation is only latex which is generated from monomers, initiator, buffer, surfactants, and water using the synthesis process as mentioned above, and eventually contains polymer, buffer, surfactant, and water. Anything other than latex adding during the paint formulation, like coalescing solvent and surfactant, are not directly part of the binder formulation. The high and low carboxyl functional latex formulations possess theoretical acid numbers around 17 and 5, respectively, and the carboxyl functional monomer weight percentage based on total weight is between 2.3 to 3.0% and 0.60 to 0.7%, respectively.

(38) TABLE-US-00005 TABLE 5 Fast-Dry White Traffic Paint Formulation Components Function Weight, pounds Order of Addition Latex, 45-60% solids Binder 460.1 Tamol 901 Dispersant 7.2 Surfynol CT-136 Surfactant 2.8 Drew L-493 Defoamer 2.0 Ti-Pure R-900 (TiO2) White pigment 100.0 Omyacarb-5 (Calcium carbonate) Filler 760.6 Mix the above at a sufficient speed for about 15 minutes, then add: Methanol Solvent 30.0 Eastastripe Coalescing solvent 23.0 Drew L-493 Defoamer 3.5 Natrosol 250HR (2% aqueous) Thickener 7.0 Water Solvent 11.6

(39) TABLE-US-00006 TABLE 6 Fast-Dry Yellow Traffic Paint Formulation Components Function Weight, pounds Order of Addition Latex, 45-60% solids Binder 470.8 Tamol 901 Dispersant 7.2 Surfynol CT-136 Surfactant 2.8 Drew L-493 Defoamer 2.0 Ti-Pure R-900 (TiO2) White pigment 20.0 Omyacarb-5 (Calcium carbonate) Filler 750.0 Hansa Yellow 11-2400 Yellow pigment 32.0 Bayferrox 3950 Yellow pigment 3.0 Mix the above at a sufficient speed for about 15 minutes, then add: Methanol solvent 30.0 Eastastripe Coalescing solvent 23.0 Drew L-493 Defoamer 3.5 Natrosol 250HR (2% aqueous) Thickener 6.0 Water Solvent 5.0

(40) Although the invention has been described in considerable detail with reference to certain preferred versions thereof; other versions are possible. For example, the coating compositions can include one or more ingredients that enhance other film properties such as gloss, durability. Therefore, the spirit and scope of the claims should not necessarily be limited to the description of the preferred embodiments contained herein.