Additives to Improve Open-Time and Freeze-Thaw Characteristics of Water-Based Paints and Coatings

Abstract

Waterborne coatings are described having an acceptable balance of properties both during the storage of coating, application and drying. The period in which irregularities in a freshly applied coating can be repaired without resulting in brush marks is referred to as the open time. Aqueous coatings generally employ dispersed high molecular weight polymers as binders. These binders often provide short open times when the coating is dried since the dispersed polymer particles tend to be immobilized quickly in the edge region of an applied coating. As a result, the viscosity of the coating increases rapidly, which leads to a limited window of workability. The instant invention provides additives that are not volatile but that will extend the time that the film is malleable after it is applied without interfering with other attributes, such as the resistance of the coating to freezing while in the can prior to application.

Claims

1-9. (canceled)

10. A coating composition comprising: at least one latex polymer; water; and at least one additive selected from the group consisting of: ##STR00006## wherein: x is 5-40; y=0-10; W is selected from the group consisting of H, SO.sub.3.sup.M.sup.+, PO.sub.3H.sup.M.sup.+, and OCH.sub.2COO.sup.M.sup.+; and M.sup.+ is selected from the group consisting of Na.sup.+, K.sup.+, NH.sup.4+ and triethanolamine.

11. The coating composition of claim 10 wherein said x is 10.

12. The coating composition of claim 10 wherein said y is 0.

13. The coating composition of claim 10 wherein said effective amount is 0.5 to 5.0 wt %.

14. The coating composition of claim 10 having a pH of 7 to 10.

15. The coating composition of claim 10 further comprising a pigment.

16. The coating composition of claim 10 wherein said latex polymer is selected from the group consisting of styrene acrylic, vinyl acrylic and acrylated ethylene vinyl acetate copolymer.

17. The coating composition of claim 10 wherein said latex polymer comprises at least one monomer selected from the group consisting of acrylic acid, acrylic acid ester, methacrylic acid and methacrylic acid ester.

18. The coating composition of claim 10 wherein said additive is: ##STR00007##

Description

DESCRIPTION

[0020] The instant invention is directed to a coating composition comprising: (a) at least one latex polymer; (b) water; and (c) at least one open time and freeze-thaw additive in an amount effective to increase the open time and freeze thaw properties of the coating composition the additive having the structural formula I:

##STR00003##

where n=2, x=10-12, y=0-10, z=0-10 and t=0-10, BO denotes a moiety derived from butylene oxide and SO denotes a moiety derived from styrene oxide and R is hydrogen or a C.sub.1-C.sub.22 alkyl group and wherein the additive is present in an amount greater than about 0.5% by weight of the polymer.

[0021] The invention is further directed to a coating composition comprising: (a) at least one latex polymer; (b) water; and (c) at least one open time and freeze-thaw additive in an amount effective to increase the open time and freeze thaw properties of the coating composition the additive having the structural formula II:

##STR00004##

where n=1-3, x=1-5, y=0-10, z=5-40, W is selected from the group consisting of hydrogen and Z.sup.M.sup.+ where Z is selected from the group consisting of SO.sub.3.sup. and PO.sub.3.sup.2, and M.sup.+ is selected from the group consisting of Na.sup.+, K.sup.+, NH.sub.4.sup.+, or an alkanolamine; and wherein the additive is present in an amount greater than about 0.5% by weight of the polymer. Preferably, x=1-3 and more preferably x=1-2.

[0022] This compounds of formula I and II provide improvements in water-based latex paints. More specifically, the improvements are (1) the increase of the open time of water based latex paints and (2) the increase in the number of times that the paint can be frozen and then thawed before it loses it integrity as a uniform dispersion.

[0023] Additional compounds which are useful in providing improved properties to the coating compositions of the invention are selected from the group consisting of:

##STR00005##

where x=5-40 preferably is x=10; y=0-10, preferably is y=0; W is selected from the group consisting of H, sulfate (SO.sub.3.sup.M.sup.+), phosphate (PO.sub.3H.sup.(M)) and carboxylate (OCH.sub.2COO.sup.M.sup.+) where M.sup.+ is selected from the group consisting of Na.sup.+, K.sup.+, NH.sub.4.sup.+ and triethanolamine.

[0024] The compounds of the invention can be used in a number of ways for improving open time characteristics, freeze-thaw cycles, as well as drying time characteristics, of latex binders, paints, inks and other coatings. The present invention may optionally employ polymerizable reactive alkoxylated monomers as a reactant during emulsion polymerization to form the latex polymer. The present invention may employ one or more surface active alkoxylated compounds of the formula I or II as a surfactant (e.g., emulsifier) during emulsion polymerization to form the latex polymer. The present invention also uses compounds of the formula I or II as an additive to latex polymer-containing formulations such as coatings, including but not limited to paints; as well as an additive for adhesives, including but not limited to pressure sensitive adhesives; glues; resins; sealants; inks, including but not limited to UV inks, conventional inks, hybrid inks, and water-based inks; and the like.

[0025] The invention also provides a latex paint composition which is freeze-thaw stable with improved open time, wet edge time and drying time characteristics.

[0026] In an alternate embodiment, the latex coating composition contains an open time additive in an amount effective to lengthen the open time of the composition to greater than 4 minutes, typically greater than 6 minutes. In one embodiment, improved open time characteristics means that the open time of a coating or adhesive is made greater than 4 minutes. In another embodiment, improved open time characteristics means that the open time of a coating or adhesive is made greater than 6 minutes. In a further embodiment, improved open time characteristics means that the open time of a coating or adhesive is made greater than 8 minutes. In another embodiment, improved open time characteristics means that the open time of a coating or adhesive is made greater than 10 minutes. In alternate embodiment, improved open time characteristics means that the open time of a coating or adhesive is made greater than 12 minutes.

[0027] The coating compositions of the invention can optionally contain additives such as one or more film-forming aids or coalescing agents. Suitable firm-forming aids or coalescing agents include plasticizers and drying retarders such as high boiling point polar solvents. Other conventional coating additives such as, for example, dispersants, additional surfactants (i.e. wetting agents), rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants such as colored pigments and dyes, waxes, perfumes, co-solvents, and the like, can also be used in accordance with the invention.

[0028] The aqueous coating compositions of the invention can be subjected to freeze-thaw cycles using ASTM method D2243-82 or ASTM D2243-95 without coagulation.

[0029] In one preferred embodiment of the invention, the aqueous coating composition is a latex paint composition comprising at least one latex polymer derived from at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters and at least one compound of the formula I or II; at least one pigment and water. As mentioned above, the at least one latex polymer can be a pure acrylic, a styrene acrylic, a vinyl acrylic or an acrylated ethylene vinyl acetate copolymer.

[0030] The present invention further includes a method of preparing an aqueous coating composition by mixing together at least one latex polymer derived from at least one monomer and mixed with a compound of the formula I or II and at least one pigment. Typically, the latex polymer is in the form of a latex polymer dispersion. The additives discussed above can be added in any suitable order to the latex polymer, the pigment, or combinations thereof, to provide these additives in the aqueous coating composition. In the case of paint formulations, the aqueous coating composition typically has a pH of from 7 to 10.

[0031] In this particular invention, the additives were added to the paint after it was formulated and were mixed in at levels of 0.05%-5.0% using non-aggressive blade mixing.

[0032] The most preferred compounds were found to be (see the introduction to the example table for the key to the abbreviations)

POE(16)DSP reacted with one mole of AGE
POE(16)DSP reacted with two moles of AGE
POE(10)TSP reacted with one mole of AGE
POE(10)TSP reacted with one mole of AGE and then sulfated
POE(10)TSP reacted with two moles of AGE
POE(10)TSP reacted with two moles of AGE and then sulfated
POE(10) beta naphthol
DDBSA formulated with TEA, water and a water soluble reverse block copolymer.

[0033] Where the abbreviations stand for: F/T=Freeze/thaw, O/T=Open time, DSP=distyrenated phenol, TSP=tristyrenated phenol, POE=polyoxyethylene polymer chain, AGE=allyl-glycidyl ether and TCDAM=tricyclodecane monomethanol

EXAMPLES

[0034] Terms and Abbreviations [0035] F/T=Freeze/thaw [0036] O/T=Open time [0037] DSP=distyrenated phenol [0038] TSP=tristyrenated phenol [0039] POE=polyoxyethylene polymer chain [0040] AGE=allyl glycidyl ether [0041] TCDAM=tricyclodecane monomethanol

Test Procedure Descriptions

Open-Time Determination

[0042] Two stocks of water-based semi gloss latex paints were provided by Behr Paints of California. One was formulated with a standard additive to improve its open time and the other was formulated without it. The version with the additive was tested as the control for the open-time evaluations. Comparisons of the test agents were made by post-adding the agents at various percentages to aliquots of the version of the paint that was formulated without additive and then determining the open times. The post-additions were made by simple ambient mixing using an overhead mixer with a two-inch blade turning at 180 rpm.

[0043] All open-times were determined using the method outlined in ASTM method D 7488-10 and the associated method D-5608. Open-time is the length of time that flaws in a paint film can be smoothed over with a paint brush after the first coat has been applied. The test method consists of drawing down a film of paint at a certain thickness onto a Leneta contrast sheet and scratching X marks in the film at various points along its length. This is followed by conditioning the film and then attempting to smooth out the X marks at various times using a paint brush that has been presoaked in the paint. The length of time that the X marks can be painted smooth is noted for each additive (this is the open-time) and the longer the time, the better. As an additional check, the length of time that the raised edge of the original paint strip can the smoothed is also noted as an open time.

Freeze-Thaw Determinations:

[0044] Commercially available Martha Stewart Living White/Base 1 interior acrylic latex semi-gloss MSL3011 and Martha Stewart Living White/Base 1 interior acrylic latex semi-gloss MSL3011N paints (both having 50 g/L VOC) were found to have no freeze-thaw resistance under the conditions of ASTM method D2243-95. These paints were used interchangeably as a substrate to which the various test additives were post-added at various percentages. The freeze-thaw test consists of placing a container of several ml of the test paint mixture in a chamber at 18 C for 17 hours followed by allowing it to thaw under ambient conditions for 7 hours. A sample was deemed to pass a cycle if after freezing solid it thawed back to its original uniformity and flow characteristics. If the sample passed, the test was repeated up to a maximum of five freeze-thaw cycles.

[0045] The post-addition blends were made by adding the additives to 100 g aliquots of paint and blending the mixtures using an overhead metal blade mixer with a 2-inch blade turning at about 180 rpm under ambient conditions.

[0046] The control additive for the Freeze-Thaw tests was Rhodoline FT-100 (Rhodia) which is a commercially available agent sold as a freeze-thaw improver. The FT-100 is reported to be a tristyrenated phenol with about 10 moles of ethylene oxide reacted to it.

Synthesis of Additives to be Evaluated.

Additives 3-10 (See Table of Compositions, Below.)

[0047] The hydrophobes were added to a stainless steel autoclave at the levels shown in the table below, along with potassium hydroxide at catalytic levels (2-3 grams) and the autoclave sealed and heated to 105 C. Ethylene oxide was then added, at the levels indicated on the table, over the course of several hours. After all of the EO was consumed, the reaction mass was cooled and the catalyst neutralized with the addition of a small amount of acid.

Additives 12-17

[0048] Step one: The hydrophobes, TSP or DSP, are added at the levels shown in the table below to a stainless steel autoclave, along with allyl glycidyl ether (AGE) (also at the levels shown) and a catalytic amount of potassium hydroxide (2-3 grams) and the mix heated to 105 C. When all of the AGE was consumed, the reaction mass was cooled, and the product discharged.

[0049] Step 2: The styrenated phenol/AGE adducts from step 1 were then added to another autoclave and heated to 105 C. Ethylene oxide, at the level shown in the table below, was then added over the course of several hours. After all the EO was consumed, the reaction mass was cooled and the catalyst neutralized with the addition of a small amount of acid.

[0050] Step 3 (for Examples 15 and 17): Selected surfactants from steps 1 and 2 were sulfated with sulfamic acid and a trace amount of dicyandiamide catalyst in a glass reactor equipped with a stirrer, thermometer, and reflux condenser by heating to 120 C until the % sulfate was >90%. The products were then isolated as the ammonium salt.

TABLE-US-00001 Table of compositions for Additives Sulfamic acid Hydrophobe AGE EO (equiv)/ (equiv.)/(% Additive (equiv.)/(% wgt) (equiv.)/(% wgt) (% wgt) agt) Terminal group (1) (Behr paint blank NA NA NA NA NA for O/T) (2) (Commercial NA NA NA NA NA paint with no F/T) (3) POE(10) TSP TSP NA (10)/(53.43%) NA OH (1)/(45.91%) (4) POE(11.5) DSP DSP NA (11.5)/(56.1%) NA OH (1)/(32.92%) (5) POE(20)DSP DSP NA (20)/(76.6%) OH (1)/(23.18%) (6) POE(10) Beta Beta naphthol NA (10)/(62.93%) NA OH Naphthol (1)(22.92%) (7) Cydecanol NA (10)/(74.43%) NA OH POE(10)cydecanol (1)/(25.35%) (8) TCDAM NA (10)/(72.33%) NA OH POE(10)TCDAM (1)/(27.27%) (9) 4-cumylphenol NA (10)/(67.36%) NA OH POE(10)4- (1)/(32.42%) cumylphenol (10) 4-tertamylphenol NA (10)/(72.56%) NA OH POE(10)4- (1)/(27.02%) tertamylphenol (11) POE(16)DSP-AGE DSP (1)/(16.96%) (16)/(61.91%) NA OH (1)/(27.6%) (12) POE(15)DSP- DSP (2)/(19.5%) (15)/(54.68%) NA OH AGE (2) (1)/(25.8%) (13) POE(10)TSP - TSP (1)/(11.6%) (10)/(47.09%) NA OH AGE (1)/(41.06%) (14) POE(10)TSP- TSP (1)/(10.55%) (10)/(42.8%) (1)/(8.98%) OSO3 AGE Sulfated (1)/(37.32%) not neutralized (15) TSP (2)/(20.84%) (10)/(41.96%) NA OH POE(10)TSP-AGE (2) (1)/(36.93%) (16) POE(10)TSP- TSP (2)/(19.13%) (10)/(38.52%) (1)/(8.08%) OSO3 AGE (2) Sulfated (1)/(33.90%) Not neutralized

TABLE-US-00002 Table of Open-Time and Freeze-Thaw Test Results % Additive actives % on Additive Blank for Gloss For Number of Additive Open Edge X 60 Freeze- cycles Additive Description time Time Time deg Thaw passed 1 Control paint for open time: ? 4 min.. 8 min. 55.8 NA NA Behr Semi gloss with standard additive (Control for open time) 2 Commercially available 0.5% 4 min. 6 min. 58.1 0.5% None Rhodaline FT-100 in Martha 1.0% 4 min. 8 min. 58.7 1.0% None Stewart paint 1.5% 1.5% None (Control for Freeze-Thaw) 2.0% 4 min. 8 min. 63.3 2.0% 5 2.5% 5 3.0% 5 3 POE(10) TSP 0.5% 0.5% None 1.0% 1.0% 5 1.5% 1.5% 5 2.0% 2.0% 5 2.5% 2.5% 5 3.0% 3.0% 5 4 POE(11.5) DSP 0.5% 6 min 8 min. 58.6 0.5% None 1.0% 6 min 12 min 56.5 1.0% None 1.5% 1.5% None 2.0% 10 min 14 min 60.7 2.0% 5 5 POE(20)DSP 0.5% 6 min 10 min. 58.6 0.5% None 1.0% 8 min 14 min 56.5 1.0% None 1.5% 1.5% None 2.0% 10 min 20 min 60.7 2.0% None 2.5% 2.5% None 6 POE(10) Beta Naphthol 0.5% 4 min. 8 min 0.5% None 1.0% 6 min. 10 min 59.6 1.0% 4 2.0% 10 min. 14 min 61.2 2.0% 5 7 POE(10)cydecanol 0.5% 4 min. 6 min. 57.2 0.5% None 1.0% 4 min. 8 min. 58.8 1.0% None 1.5% 1.5% None 2.0% 6 min. 12 min. 60.6 2.0% None 2.5% 2.5% None 8 POE(10)TCDAM 0.5% 4 min. 6 min. 53.4 0.5% None 1.0% 6 min. 6 min. 57.2 1.0% None 2.0% 6 min. 10 min 60.0 2.0% None 9 POE(10)4-cumylphenol 0.5% 4 min. 8 min. 56.6 0.5% None 1.0% 6 min. 12 min. 55.6 1.0% None 1.5% 1.5% None 2.0% 10 min. 18 min. 62.0 2.0% None 2.5% 2.5% None 10 POE(10)4-tertamylphenol 0.5% 0.5% None 1.0% 6 min 8 min. 56.9 1.0% None 1.5% 1.5% None 2.0% 8 min. 12 min 59.7 2.0% None 2.5% 2.5% None 11 POE(16)DSP AGE 0.5% 6 min 10 min 57.3 0.5% * 1.0% 6 min 14 min 59.2 1.0% None 1.5% 1.5% None 2.0% 6 min 12 min 57.0 2.0% None 12 POE(15) DSP AGE (2) 0.5% 6 min 8 min 58.4 0.5% * 1.0% 6 min 10 min 58.5 1.0% None 1.5% 1.5% None 2.0% 6 min 10 min 62.7 2.0% 1 13 POE(10) TSP AGE 0.5% 6 min 8 min 57.8 0.5% * 1.0% 4 min 6 min 59.7 1.0% None 1.5% 1.5% 5 (#5grainy) 2.0% 4 min 6 min 63.9 2.0% 5 14 POE(10) TSP AGE 0.5% 6 min 10 min 57.9 0.5% Sulfated 1.0% 6 min 10 min 58.7 1.0% None not neutralized 1.5% 1.5% 1 2.0% 4 min 12 min 60.5 2.0% 5 15 POE(10) TSP AGE (2) 0.5% 4 min 8 min 58.0 0.5% * 1.0% 4 min 5 min 62.2 1.0% None 1.5% 1.5% 5 (#5 grainy) 2.0% 4 min 6 min 65.4 2.0% 5 16 POE(10) TSP AGE (2) 0.5% 4 min 10 min 58.3 0.5% Sulfated 1.0% 6 min 10 min 60.1 1.0% None Not neutralized 1.5% 1.5% 2 2.0% 6 min 10 min 61.9 2.0% 5 ? Indicates that it is not known whether the commercial paint has additive or not but it is used as a control for comparison purposes.

Example I

[0051] Literature teaches that ethoxylated TSP will offer improvements in the freeze-thaw performance of water-based coating formulations. Comparing additive 3 to additive 2, we see that the internally made POE(10) TSP is an improvement over the commercial material, being stable to 5 F/T cycles at 1.0% additive as opposed to 2%.

Example II

[0052] DSP, with an Appropriate Level of Ethoxylation is as Effective as TSP as a F/T Additive.

[0053] Additive 4 shows that 2% POE(11.5) DSP is as effective as the commercial TSP derivative control of additive 2 in that they both must be present at a minimum of 2%, at which level, they both pass five cycles. This example, further, shows that POE(11.5) DSP yields an O/T performance at 0.5% additive that is equal to that of the commercial standard.

Example III

The Level of Ethoxylation is Important Both to F/T and to O/T Performance of DSP Derivatives.

[0054] Comparing additive 5 to additive 4, it is evident that excessive ethoxylation damages the freeze-thaw performance while improving the O/T.

Example IV

[0055] Derivatives of DSP and TSP Other than the Original POE Offer F/T and/or OT Performances Equivalent to Those Shown in Control Tests 1 and 2.

[0056] Additives 11 and 12 indicate that POE(16)DSP reacted with one and two AGE groups yields an O/T equal to standard of Test 1.

[0057] Additives 13 and 15, which are POE(10)TSP reacted with 1 and 2 moles of AGE respectively, show open times that are equivalent to the O/T results of the standard in Test 1 together with F/T results that are extensions compared to the results of the standard in Test 2.

[0058] Additives 14 and 16 use the sulfated versions of additives 13 and 15, respectively and indicate that sulfation yields an extension in the OT performance but a slight drop in the F/T performance.

Example V

[0059] There are Additives Other than Either DSP or TSP Derivatives that Combine Acceptable F/T and O/T Capabilities.

[0060] Additive 6 compared to additives 1 and 2 indicates that POE(10) beta naphthol causes acceptable open-times and freeze-thaws.

Example VI

[0061] Additives 7, 8, 9, and 10, indicate that POE(10) cydecanol, POE(10)TCDAM, POE(10) 4-cumylphenol and POE(10) tert-amylphenol show reasonable 0/T performance, compared to the control tests 1 and 2 even though F/T performance was diminished. Again, these are non-DSP and non-TSP agents.

[0062] The contents of all references cited in the instant specifications and all cited references in each of those references are incorporated in their entirety by reference herein as if those references were denoted in the text.

[0063] While the many embodiments of the invention have been disclosed above and include presently preferred embodiments, many other embodiments and variations are possible within the scope of the present disclosure and in the appended claims that follow. Accordingly, the details of the preferred embodiments and examples provided are not to be construed as limiting. It is to be understood that the terms used herein are merely descriptive rather than limiting and that various changes, numerous equivalents may be made without departing from the spirit or scope of the claimed invention.