COATING COMPOSITIONS CONTAINING LOW VOC COMPOUNDS

Abstract

Coating compositions containing coalescents and a latex polymer, wherein the coalescent has a volatile organic content of less than about 50% and is dispersible in the coating composition.

Claims

1-20. (canceled)

21. A low-VOC paint, comprising: water; a latex polymer comprising a surfactant and polymer particles comprising a homopolymer or copolymer including at least one of an acrylate or a methacrylate; a pigment; and a coalescent having the formula:
R.sup.1(C(O)O)R.sup.2 wherein: R.sup.1 is an aromatic group having 3 to 24 carbon atoms:and R.sup.2 is a hydrocarbyl moiety having 3 to 24 carbon atoms; with the proviso that R.sup.1 and R.sup.2 together do not include any aliphatic unsaturated carbon-carbon bonds; wherein the coalescent has a volatile organic content of no greater than 50 wt-%; wherein the total VOC in the paint is no greater than 5 grams per 100 grams polymer solids; and wherein the paint contains sufficient TiO.sub.2 pigment to be substantially visually opaque when applied at a thickness of 3 mils (0.0762 mm) and dried.

22. The paint of claim 21 wherein the coalescent is nonreactive in the paint, and is dispersible in the paint to form a uniform mixture.

23. The paint of claim 21 wherein the paint forms a coalesced film at a temperature of about 4 C. to about 10 C.

24. The paint of claim 21 wherein the coalescent has a volatile organic content of no greater than about 30 wt-%.

25. The paint of claim 21 comprising a mixture of coalescents, wherein the mixture has a volatile organic content of no greater than about 50 wt-%, and wherein at least one of the coalescents is nonreactive in the paint, has a volatile organic content of no greater than 15 wt-%, is dispersible in the paint to form a uniform mixture, and has the recited formula; wherein the mixture of coalescents is selected to facilitate, and used in an amount that facilitates, the formation of a polymer film of the latex polymer at a temperature of less than about 25 C.

26. The paint of claim 21 wherein the coalescent is used in an amount less than 2 wt-%, based on polymer solids, but which facilitates the formation of a polymer film of the latex polymer at a temperature of less than about 25 C.

27. A low-VOC paint, comprising: water; a pigment; a latex polymer comprising a surfactant and polymer particles emulsified or suspended in an aqueous medium, wherein the polymer particles comprise a homopolymer or copolymer including at least one of an acrylate or a methacrylate; and a coalescent having the formula:
R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: R.sup.1 is an organic group having at least 3 and less than 100 carbon atoms: X is a divalent organic group; r is 0 or 1; n is 1 to 10; and R.sup.2 is hydrogen or an organic group having at least 3 and less than 100 carbon atoms; wherein the total VOC in the paint is no greater than 5 grams per 100 grams polymer solids; and wherein the paint contains sufficient TiO.sub.2 pigment to be substantially visually opaque when applied at a thickness of 3 mils (0.0762 mm) and dried.

28. The paint of claim 27 wherein the coalescent has a volatile organic content of no greater than 5 wt-%, is nonreactive in the paint, and is dispersible in the paint to form a uniform mixture.

29. The paint of claim 27 wherein the coalescent is selected to facilitate, and used in an amount that facilitates, the formation of a polymer film of the latex polymer at a temperature of less than 25 C.

30. The paint of claim 29 wherein the coalescent is selected to facilitate, and used in an amount that facilitates, the formation of a polymer film of the latex polymer at a temperature of 4 C. to 10 C.

31. The paint of claim 29 wherein the total VOC in the paint is no greater than 2 grams per 100 grams polymer solids.

32. The paint of claim 27 wherein the coalescent is used in an amount less than 2 wt-%, based on polymer solids, but which facilitates the formation of a polymer film of the latex polymer at a temperature of less than about 25 C.

33. A low-VOC paint, comprising: water; a pigment; a latex polymer comprising a surfactant and polymer particles emulsified or suspended in an aqueous medium, wherein the polymer particles comprise a homopolymer or copolymer including at least one of an acrylate or a methacrylate; and a mixture of coalescents, wherein the mixture has a volatile organic content of no greater than 15 wt-%, and wherein at least one of the coalescents is nonreactive in the paint, is dispersible in the paint to form a uniform mixture, and has the formula:
R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: R.sup.1 is an organic group having at least 3 and less than 100 carbon atoms, wherein the organic group is an aliphatic group, alicyclic group, heterocyclic group, or combinations thereof: X is a divalent organic group; r is 1; n is 1; and R.sup.2 is hydrogen or an organic group having at least 3 and less than 100 carbon atoms; with the proviso that R.sup.1 and R.sup.2 together do not include any aliphatic unsaturated carbon-carbon bonds; wherein the total VOC in the paint is no greater than 5 grams per 100 grams polymer solids; and wherein the paint contains sufficient TiO.sub.2 pigment to be substantially visually opaque when applied at a thickness of 3 mils (0.0762 mm) and dried.

34. The paint of claim 33 wherein the coalescent is used in an amount less than 2 wt-%, based on polymer solids, but which facilitates the formation of a polymer film of the latex polymer at a temperature of less than about 25 C.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] The present invention is directed to coating compositions that include coalescents, which can optionally also function as plasticizers and/or solvents, and coatings prepared therefrom. Preferably, the coating compositions are in the form of paints. Preferably, such coating compositions include a polymer, preferably, a latex polymer, in addition to one or more coalescents. The coalescent is dispersible in the coating composition which is preferably stable over time (i.e., the coalescent does not phase separate from the coating composition upon standing at 49 C. for four weeks).

[0021] The coating compositions of the present invention are advantageous in that they have a relatively low volatile organic content without sacrificing the balance of properties desired for an applied (i.e., dry) coating, such as a paint. For example, the coating compositions of the present invention provide an applied coating having a preferred scrub resistance, as determined by the test set forth in the Examples Section herein below, of at least about that of TEXANOL, which is an alcohol/ester made from trimethylpentane diol and isobutyric acid ((H.sub.3C).sub.2CHC(O)OCH.sub.2C(CH.sub.3).sub.2CH.sub.2(OH)CH(CH.sub.3).sub.2).

[0022] Preferably, the coating compositions include a compound having a relatively low volatile organic content (VOC), and more preferably, a relatively low molecular weight. Typically, the volatile organic content, as determined by the test set forth in the Examples Section herein below, is no greater than about 50%, preferably, no greater than about 30%, more preferably, no greater than about 20%, and most preferably, no greater than about 15%, based on the original weight of the coalesent. Preferably, the number average molecular weight of such compounds is no greater than about 750, and more preferably, less than about 500.

[0023] Preferably, such compounds are good coalescents. That is, they preferably and advantageously provide good film forming properties for a latex polymer. More preferably, a particularly desirable group of compounds are those that provide good film forming properties at low temperatures (e.g., below room temperature), as determined by the test set forth in the Examples Section herein below. Preferably, such compounds facilitate the formation of polymer films of a latex polymer at a temperature of less than about 25 C. (more preferably, at a temperature of about 4 C. to about 10 C., and most preferably, at a temperature of about 4 C. to about 5 C.).

[0024] Preferably, such low VOC compounds are of the formula R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: n is 1 to 10; R.sup.1 is an organic group, preferably, having less than 100 carbon atoms, and more preferably, having 3 to 24 carbon atoms; R.sup.2 is hydrogen or an organic group, preferably, having less than 100 carbon atoms; and X is a divalent organic group, preferably, having 2 to 8 carbon atoms, and more preferably, 3 to 5 carbon atoms; and r is 0 to 1. Preferably, n is 1 to 5, more preferably, n is 1 to 3, and most preferably, n is 2 to 3.

[0025] Preferably, R.sup.1 is a hydrocarbyl moiety, although for certain preferred embodiments R.sup.1 is an organic group that includes substituents selected from the group of nonperoxidic oxygen atoms, carbonyl groups, hydroxyl groups, and combinations thereof, more preferably, substituents selected from the group of nonperoxidic oxygen atoms, hydroxyl groups, and combinations thereof, and most preferably, nonperoxidic oxygen atoms. For certain embodiments, R.sup.1 has the formula R.sup.3(CH.sub.2).sub.m(O(CH.sub.2).sub.p).sub.q wherein R.sup.3 is an alkyl or aryl group, m is 0 to 24, p is 1 to 4 (preferably, p is 1 to 2), and q is 0 to 50. In this preferred formulation for R.sup.1, m+pq is preferably less than about 23.

[0026] Preferably, X is a divalent hydrocarbyl moiety, although for certain preferred embodiments, X is an organic group that includes substituents selected from the group of nonperoxidic oxygen atoms, carbonyl groups, and combinations thereof, and more preferably, nonperoxidic oxygen atoms and carbonyl groups. For certain embodiments, X has the formula (CH.sub.2).sub.s wherein s is 2 to 8, and preferably, s is 3 to 5.

[0027] For certain embodiments, X includes unsaturation. Preferably, X includes at least one carbon-carbon double bond. A preferred example of such a compound is bis(2-ethylhexyl)maleate (i.e., dioctyl maleate), which is available from commercial sources such as Aldrich Chemical Co., Milwaukee, Wis.

[0028] Preferably, R.sup.2 is hydrogen, although for certain preferred embodiments R.sup.2 is R.sup.1 as defined above. For certain embodiments, r is one, preferably when R.sup.2 is hydrogen.

[0029] For certain embodiments, R.sup.1 includes at least three carbon atoms when X is not (CH.sub.2).sub.s wherein s is 2 to 8; and R.sup.1 and R.sup.2 together (i.e., the coating composition) include less than two aliphatic unsaturated carbon-carbon bonds when r is zero, preferably, R.sup.1 and R.sup.2 together (i.e., the coating composition) do not include any aliphatic unsaturated carbon-carbon bonds when r is zero, and more preferably, R.sup.1 and R.sup.2 together (i.e., the coating composition) do not include any aliphatic unsaturated carbon-carbon bonds.

[0030] For certain embodiments, R.sup.1 is an organic group having 3 to 24 carbon atoms and substituents selected from the group of oxygen atoms, carbonyl groups, hydroxyl groups, and combinations thereof; and R.sup.2 is hydrogen.

[0031] A preferred group of such compounds have the formula: R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: R.sup.1 is an organic group; X is a divalent organic group; r is 0 to 1; n is 1 to 10; and R.sup.2 is hydrogen or an organic group; with the proviso that R.sup.1 includes at least three carbon atoms when X is not (CH.sub.2).sub.s wherein s is 2 to 8; with the proviso that the coalescent has less than two aliphatic unsaturated carbon-carbon bonds when r is zero. Such compounds can be made from caprolactone and an alcohol, for example.

[0032] Another preferred group of such compounds have the formula: R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: R.sup.1 is an organic group; X is a divalent organic group; r is 0 to 1; n is 1 to 10; and R.sup.2 is hydrogen or an organic group; with the proviso that R.sup.1 includes at least three carbon atoms when X is not (CH.sub.2).sub.s wherein s is 2 to 8; with the proviso that the coalescent does not include aliphatic unsaturated carbon-carbon bonds; with the proviso that r is one when R.sup.2 is hydrogen.

[0033] Another preferred group of such compounds have the formula: R.sup.1(C(O)X.sub.rO).sub.nR.sup.2 wherein: R.sup.1 has the formula R.sup.3(CH.sub.2).sub.m(O(CH.sub.2).sub.p).sub.q wherein R.sup.3 is an alkyl or aryl group, m is 0 to 24, p is 1 to 4, and q is 0 to 50; X has the formula -(CH.sub.2).sub.s-, wherein s is 2 to 8; r is 0 to 1; n is 1 to 10; and R.sup.2 is hydrogen or R.sup.1.

[0034] Another preferred group of such compounds have the formula: R.sup.1(C(O)XO).sub.nH wherein: R.sup.1 is a hydrocarbyl moiety or an organic group containing substituents selected from the group of nonperoxidic oxygen atoms, hydroxyl groups, and combinations thereof; X is a divalent hydrocarbyl moiety or an organic group containing nonperoxidic oxygen atoms and carbonyl groups; and n is 1 to 10. Such compounds can be made from a glycidyl ester of neodecanoic acid (e.g. CARDURA E10) and a carboxylic acid, for example. Another preferred group of such compounds have the formula: R.sup.1(C(O)XO).sub.nH wherein: R.sup.1 is a hydrocarbyl moiety or an organic group containing substituents selected from the group of nonperoxidic oxygen atoms, hydroxyl groups, and combinations thereof; X has the formula (CH.sub.2).sub.s, wherein s is 2 to 8; and n is 1 to 10.

[0035] Another preferred group of such compounds have the formula: R.sup.1(C(O)XO).sub.nH wherein: R.sup.1 is a hydrocarbyl moiety or an organic group containing nonperoxidic oxygens; X is an organic group containing nonperoxidic oxygens and carbonyl groups; and n is 1 to 10.

[0036] These compounds can be formed using standard organic synthesis techniques, which are well known to one of skill in the art. Specific syntheses are set forth in the Examples Section herein below.

[0037] The preferred polymers of the coating compositions of the present invention include latex polymers (i.e., latices). These are well known in the paint art and are typically particles emulsified or suspended in an aqueous medium. They include, for example, the polymerization products of ethylenically unsaturated monomers, such as alkyl and alkoxy acrylates or methacrylates, vinyl esters of saturated carboxylic acids, monoolefins, conjugated dienes, optionally with one or more monomers, such as, for example, styrene, methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, acrylonitrile, and vinyl chloride. The latex polymers can have a wide range of glass transition temperatures, depending on the desired properties of the resultant coating.

[0038] The amount of polymers and the low VOC compounds (e.g., coalescents) present in the coating compositions of the present invention include an amount that provides the desired result. Preferably, one or more relatively low VOC compounds, which preferably function as coalescents, are present in a coating composition in an amount of at least about 1 percent by weight (wt-%), more preferably, at least about 2 wt-%, and most preferably, at least about 5 wt-%, based on polymer solids. Preferably, one or more relatively low VOC compounds are present in a coating composition in an amount of no greater than about 50 wt-%, and more preferably, no greater than about 25 wt-%, based on polymer solids. When mixtures of such coalescents are used, the numerical values of the variables in the formulas described herein are averages.

[0039] Other components of the coating compositions of the present invention include those typically used in paint formulations, such as pigments, fillers, thickeners, biocides, mildewcides, surfactants, dispersants, defoamers, and the like. The coating compositions can be made using standard techniques known in the paint industry.

EXAMPLES

[0040] The following examples are offered to aid in understanding of the present invention and are not to be construed as limiting the scope thereof. Unless otherwise indicated, all parts and percentages are by weight.

VOC Testing:

[0041] Testing of coalescents were performed using ASTM method D2369-90. Approximately 0.5 gram (g) of coalescent was weighed into an aluminum weighing dish and placed in a forced air oven at 110 C. for 1 hour. The dish was then reweighed and the mass lost represents the percent (%) VOC of the coalescent.

Scrub Resistance:

[0042] The coating was drawn down on a black vinyl scrub test chart (available from the Leneta Company) with a standard 3-mil (0.0762 millimeter (mm)) Bird film applicator (available from Byk Gardner). The film was allowed to dry at room temperature for 7 days. Scrub resistance was measured with a Gardner Abrasion Tester (available from Byk Gardner) using 10 g of scrub media. The number of cycles until the coating film was first removed was recorded.

Low Temperature Coalescence (LTC):

[0043] The coating was drawn down on a Penopac paper chart (available from the Leneta Company) with a standard 3-mil Bird film applicator. The chart was then put in the refrigerator at 40 F. (4.4 C.) until dry. Coating films that did not exhibit any cracking were determined to pass. Any cracking of the film was considered a failure.

EXAMPLE 1

Preparation of Coalescent Compounds

Run 1. Preparation of Coalescent

[0044] Epsilon-caprolactone (2-oxepanone) (174 g), 1-dodecanol (173 g), and FASCAT 2003 (stannous octoate, available from Atofina Chemicals) (0.2 g) were charged to a 4-neck 500-mL round bottom flask fitted with mechanical stirring. The contents of the flask was heated to 150 C. and held until the free caprolactone level was below 0.5% as measured by GC (approximately four hours), then cooled to room temperature.

Runs 2-20. Preparation of Coalescents

[0045] A variety of coalescents were prepared following the procedure of Example 1, Run 1, with the exception that the 174 g caprolactone was varied according to the amount listed in Table 1A, and the 173 g of 1-dodecanol used in Example 1, Run 1 was replaced with the alcohol and amount listed in Table 1A.

TABLE-US-00001 TABLE 1A caprolactone (grams)/ Molar Ratio alcohol Caprolactone: % Run Alcohol (grams) Alcohol VOC 1 1-dodecanol 174/173 1.64:1 7.0% 2 1-dodecanol 200/163 2:1 6.0% 3 1-dodecanol 225/147 2.5:1 4.0% 4 1-dodecanol 240/130.5 3:1 3.0% 5 1-dodecanol 265/108 4:1 2.0% 6 benzyl alcohol 228/108 2:1 9.0% 7 2,2,4-trimethyl 1,3- 196/140 1.7:1 15% pentane diol (TMPD) 8 2-ethylhexanol, 157/200 1.5:1 10% 2 mol EO 9 2-amino-2-methyl-1- 228/71.2 2.5:1 3.0% propanol (AMP-95) 10 1-hexanol 228/81.8 2.5:1 5.0% 11 2-butoxyethanol 228/94.4 2.5:1 8.0% (butyl cellosolve) 12 1-butanol 228/74.1 2.5:1 7.0% 13 2(2-butoxyethoxy) 228/129.8 2.5:1 9.0% ethanol (butyl carbitol) 14 1-octanol 228/104.2 2.5:1 5.0% 15 2-propxyethanol 228/83.2 2.5:1 9.0% (propyl cellosolve) 16 1-propanol 228/48 2.5:1 11.0% 17 2-butyl-2ethy1-1,3 174/98 2.5:1 3.5% propanediol 18 1,3-butanediol 228/72 2.5:1 3.0% 19 2-methoxyethanol 228/60.8 2.5:1 7.0% (methyl cellosolve) 20 2-ethoxyethanol 228/72.1 2.5:1 7.5% (cellosolve) *TEXANOL is 99.5% VOC by this method

EXAMPLE 2

Preparation of Coalescent Compounds

[0046] Run 1. Preparation of Coalescent from Cardura E10

[0047] CARDURA E10 (glycidyl ester of neodecanoic acid, available from Shell Chemical) (228 g) was charged to a 4-neck 500-mL round bottom flask equipped with mechanical stirring. The flask was heated to 140 C. and 88 g isobutyric acid was fed into the flask over 90 minutes. The contents of the flask were held at 140 C. for 2 hours and cooled to room temperature.

Runs 2-3. Preparation of Coalescents

[0048] A variety of coalescents were prepared following the procedure of Example 2, Run 1, with the exception that the 88 g of isobutyric acid used in Example 2, Run 1 was replaced with the acid listed in Table 2A.

TABLE-US-00002 TABLE 2A Amount % Run Acid (Grams) VOC 1 Isobutyric acid 88 7.0% 2 Acetic acid 60 9.0% 3 Propionic acid 74 10.0%

EXAMPLE 3

Preparation of Coating Compositions

[0049] Various coating compositions were prepared by mixing the ingredients listed in Table 3A. For each composition the coalescent is as described in Examples 1 and 2.

TABLE-US-00003 TABLE 3A Material Description Grams Water 62.0 Ethylene glycol 35.0 AMP-95 Amine, Angus 1.0 TAMOL 731 Dispersant, Rohm&Haas 10.0 DEHYDRAN 1620 Defoamer, Cognis 1.0 RCL-535 TiO.sub.2, Millennium 245.0 KATHON LX 1.5% Biocide, Rohm&Haas 1.7 Emulsion polymer 453 Ammonium 2.0 hydroxide Coalescent 26.3 Ethylene glycol 20.9 SURFYNOL 504 Surfactant, Air Products 1.0 ACRYSOL RM- Thickener, Rohm&Haas 4.0 2020NPR ACRYSOL RM-6 Thickener, Rohm&Haas 31.0 FOAMASTER SA-3 Defoamer, Cognis 3.5 Water 156.0

TABLE-US-00004 TABLE 3B Molar Ratio Scrub Example 1, Caprolactone: (relative to Run Alcohol Alcohol TEXANOL) LTC 1 1-dodecanol 1.7:1 1.27 Pass 2 1-dodecanol 2:1 1.09 Pass 3 1-dodecanol 2.5:1 Pass 4 1-dodecanol 3:1 1.07 Pass 5 1-dodecanol 4:1 0.71 Pass 6 Benzyl alcohol 2:1 Pass 7 2,2,4-Trimethyl 1.7:1 0.81 Pass 1,3-pentanediol (TMPD) 8 2-ethylhexanol, 1.5:1 0.96 Pass 2 mol EO 9 2-amino-2-methyl- 2.5:1 Fail 1-propanol (AMP-95) 10 1-hexanol 2.5:1 1.10 Pass 11 2-butoxyethanol 2.5:1 1.35 Pass (butyl cellosolve) 12 1-butanol 2.5:1 1.27 Pass 13 2(2-butoxyethoxy) 2.5:1 Pass ethanol (butyl carbitol) 14 1-octanol 2.5:1 Pass 15 2-propxyethanol 2.5:1 Pass (propyl cellosolve) 16 1-propanol 2.5:1 Pass 17 2-butyl-2ethy1-1,3 2.5:1 Pass propanediol 18 1,3-butanediol 2.5:1 Fail 19 2-methoxyethanol 2.5:1 Pass (methyl cellosolve) 20 2-ethoxyethanol 2.5:1 Pass (cellosolve) TEXANOL LTC: Pass, Scrub = 1.0

TABLE-US-00005 TABLE 3C Example 2, Run Acid LTC 1 Isobutyric acid Pass 2 Acetic acid Pass 3 Propionic acid Pass

TABLE-US-00006 TABLE 3D Example 3, Compound VOC LTC Isodecyl benzoate 15% Pass Bis(2-ethylhexyl) 0.6% Pass adipate Bis(2-ethylhexyl) 3% Pass maleate

[0050] Having thus described the preferred embodiments of the present invention, those skilled in the art will readily appreciate that the teachings found herein may be applied to yet other embodiments within the scope of the claims hereto attached. The complete disclosure of all patents, patent documents, and publications are incorporated herein by reference as if individually incorporated.