AMINE COMPOUND, REACTIVE COALESCING AGENT, COATING COMPOSITION, COATING LAYER AND RELATED METHODS

Abstract

There is provided a reactive coalescing agent for a coating formulation that is substantially free from volatile organic compounds (VOCs), the coalescing agent comprising one or more amine compounds represented by general formula (I). Also provided are a coating composition, a coating layer, a method of preparing said reactive coalescing agent and a method of preparing said coating layer.

##STR00001##

Claims

1. A coalescing agent for a coating formulation that is substantially free from volatile organic compounds (VOCs), the coalescing agent comprising one or more amine compounds represented by general formula (I): ##STR00024## wherein X is selected from O and NH; R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from H, alkyl and alkenyl; R.sup.5, R.sup.6 and R.sup.7 are H; R.sup.8 is selected from alkyl, alkenyl, cycloalkyl, cycloalkenyl, alkylhydroxy, hydroxyalkyl, oxy, alkyloxyalkyl, (alkyloxy).sub.nalkyl where n≥1, alkylacrylate, alkyl(meth)acrylate, alkylacrylamide, alkylamine or (alkyloxy).sub.malkyl-O—C(═O)-alkylamine where m≥0 and wherein one or more of the H atoms is/are optionally replaced by hydroxy, alkoxy, hydroxyalkyl, halogen, haloalkyl, cyano, cyanoalkyl and nitro.

2. (canceled)

3. The coalescing agent of claim 1, wherein the amine compound has a boiling point that is more than about 250° C.

4. The coalescing agent of claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H, linear or branched (C.sub.1-C.sub.10)-alkyl and linear or branched (C.sub.1-C.sub.10)-alkenyl.

5. The coalescing agent of claim 1, wherein R.sup.8 is selected from linear or branched (C.sub.1-C.sub.30)-alkyl, linear or branched (C.sub.2-C.sub.30)-alkenyl, (C.sub.3-C.sub.30)-cycloalkyl, (C.sub.3-C.sub.30)-cycloalkenyl, linear or branched (C.sub.1-C.sub.30)-alkylhydroxy, linear or branched hydroxy-(C.sub.1-C.sub.30)-alkyl, linear or branched (C.sub.1-C.sub.30)-alkyl-oxy-(C.sub.1-C.sub.30)-alkyl, linear or branched [(C.sub.1-C.sub.30)-alkyl-oxy].sub.n-(C.sub.1-C.sub.30)-alkyl where n≥1, (C.sub.1-C.sub.30)-alkyl-acrylate, (C.sub.1-C.sub.30)-alkyl-(meth)acrylate, (C.sub.1-C.sub.30)-alkyl-acrylamide, linear or branched (C.sub.1-C.sub.30)-alkylamine, or [(C.sub.1-C.sub.30)-alkyl-oxy).sub.m-(C.sub.1-C.sub.30)-alkyl-O—C(═O)—(C.sub.1-C.sub.30)-alkylamine where m≥0.

6. (canceled)

7. The coalescing agent of claim 1, wherein R.sup.8 is selected from one of the following: —R.sup.9—OH; —R.sup.10; —(R.sup.11—O).sub.n—R.sup.12; —R.sup.13—O—C(═O)—C(CH.sub.3)═CH.sub.2; —R.sup.14(OH)—R.sup.15—O—C(═O)—C(CH.sub.3)═CH.sub.2; —R.sup.16—NR.sup.xR.sup.y; or —(R.sup.17—O).sub.m—R.sup.18—O—C(═O)—R.sup.19—NR.sup.xR.sup.y, where n≥1, m≥0, R.sup.9 to R.sup.19 are each alkyl, and where R.sup.x and R.sup.y are each independently selected from H, alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl and alkylaryl.

8. (canceled)

9. The coalescing agent of claim 1, wherein R.sup.8 is (i) hydroxyalkyl selected from the group consisting of hydroxymethyl, hydroxyethyl, 2-hydroxyethyl hydroxypropyl, 2-hydroxypropyl, hydroxybutyl, hydroxypentyl and hydroxyhexyl; (ii) (alkyloxy).sub.nalkyl selected from the group consisting of methoxymethyl, methoxyethyl, methoxypropyl, methoxybutyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, propoxymethyl, propoxyethyl, propoxypropyl, propoxybutyl, methoxymethoxymethyl, methoxymethoxyethyl, methoxymethoxypropyl, methoxymethoxybutyl, ethoxyethoxymethyl, ethoxyethoxyethyl, ethoxyethoxypropyl, ethoxyethoxybutyl, propoxypropoxymethyl, propoxypropoxyethyl, propoxypropoxypropyl, propoxypropoxybutyl, methoxymethoxymethoxymethyl, methoxymethoxymethoxyethyl, methoxymethoxymethoxypropyl, methoxymethoxymethoxybutyl, ethoxyethoxyethoxymethyl, ethoxyethoxyethoxyethyl, ethoxyethoxyethoxypropyl, ethoxyethoxyethoxybutyl, propoxypropoxypropoxymethyl, propoxypropoxypropoxyethyl, propoxypropoxypropoxypropyl and propoxypropoxypropoxybutyl; (iii) alkyl(meth)acrylate selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 3-methylbutyl (meth)acrylate, amyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, ethylhexyl (meth)acrylate and decyl (meth)acrylate; or (iv) alkyl(meth)acrylate substituted with hydroxy that is selected from the group consisting of hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate.

10. The coalescing agent of claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are all H atoms.

11. The coalescing agent of claim 1, wherein the amine compound comprises more than twelve carbon atoms per basic nitrogen atom.

12. The coalescing agent of claim 1, wherein the coalescing agent is configured to spontaneously react with a polymer in a coating composition during/upon drying to form a coating layer.

13. The coalescing agent of claim 12, wherein the coalescing agent is configured to form a chemical interaction with the polymer during/upon drying, wherein the chemical interaction is at least one of an ionic interaction or a covalent interaction.

14. The coalescing agent of claim 1, wherein the amine compound is selected from the following compounds (1) to (12): ##STR00025## ##STR00026##

15. (canceled)

16. A coating composition comprising one or more coalescing agent(s) of claim 1 and one or more polymer(s) configured to spontaneously react with the coalescing agent(s) during/upon drying of the coating composition to form a coating layer.

17. The coating composition of claim 16, wherein the polymer comprises one or more acid group(s) and/or salts thereof selected from carboxylic acids (—C(═O)OH)), sulfonic acids (—S(═O).sub.2OH), phosphonic acids (—P(═O)(OH).sub.2), amine neutralized carboxylic acids, amine neutralized sulfonic acids, amine neutralized phosphonic acids, carboxylic acid-amine salts, sulfonic acid-amine salts and phosphonic acid-amine salts.

18. The coating composition of claim 17, wherein the carboxylic acids and derivatives thereof comprises acrylic acid and derivatives thereof; methacrylic acid and derivatives thereof; maleic acid and derivatives thereof; itaconic acid and derivatives thereof and combinations thereof.

19. The coating composition of claim 16, wherein the amount of the coalescing agent in the composition is from about 0.2 wt % to about 20.0 wt % of the composition.

20. The coating composition of claim 16, wherein the coating composition is substantially devoid of volatile organic compounds (VOCs).

21. The coating composition of claim 16, wherein the coating composition is a water-based coating composition.

22. The coating composition of claim 16, wherein the coating composition is a water-based paint coating composition.

23. A coating layer comprising one or more coalescing agent(s) of claim 1 chemically coupled to one or more polymer(s) via at least one of an ionic interaction or a covalent interaction.

24. The coating layer of claim 23, wherein the layer has one or more of the following properties: odourless, non-tacky, non-sticky, substantially colourless in solution, substantially insoluble in water, substantially do not blister in water, substantially do not delaminate in water, chemically and/or physically stable, excellent resistance towards natural exposure/weathering and substantially inert towards ultraviolet (UV) light.

Description

BRIEF DESCRIPTION OF FIGURES

[0147] FIG. 1 is a schematic diagram 100 for illustrating the operation and interactions of amine based coalescing agents designed in accordance with various embodiments disclosed herein with a polymer during/upon drying at a molecular level.

[0148] FIG. 2 is a schematic diagram 200 for illustrating the operation and interactions of amine based coalescing agents designed in accordance with various embodiments disclosed herein with a polymer during/upon drying at a material/coatings level.

[0149] FIG. 3 is a schematic diagram 300 for illustrating the operation and interactions of amine based coalescing agents (having dual functionality) with a polymer containing —COOH group(s) on aging at a molecular level in accordance with various embodiments disclosed herein.

[0150] FIG. 4A is a graph showing the boiling points of ACA4, ACA5, ACA6 and ACA7 prepared in accordance with various embodiments disclosed herein, relative to butyl carbitol (BC) and texanol ester alcohol which were used as comparison/control.

[0151] FIG. 4B is a graph showing the volatility (% wt loss when heated at 110±5° C. for 1 hour as per USA EPA 24 method) of ACA4, ACA5, ACA6 and ACA7 prepared in accordance with various embodiments disclosed herein, relative to butyl carbitol (BC) and texanol ester alcohol which were used as comparison/control.

[0152] FIG. 5A is a graph showing the minimum film formation temperature (MFFT) of commercial waterborne latex 1 (L) mixed respectively with ACA4, ACA5, ACA6 and ACA7 (2 wt % of coalescing agents were used). Controls used were butyl carbitol (BC) and texanol ester alcohol. As shown, there is a reduction in the MFFT by using ACAs designed in accordance with various embodiments disclosed herein. Commercial latex 1 used as a comparative example is BASF 538A.

[0153] FIG. 5B is a graph showing the minimum film formation temperature (MFFT) of commercial waterborne latex 2 (L) mixed respectively with ACA4, ACA5, ACA6 and ACA7 (2 wt % of coalescing agents were used). Controls used were butyl carbitol (BC) and texanol ester alcohol. As shown, there is a reduction in the MFFT by using ACAs designed in accordance with various embodiments disclosed herein. Commercial latex 2 used as a comparative example is Nippon N-2398.

[0154] FIG. 5C is a graph showing the minimum film formation temperature (MFFT) of commercial waterborne latex 3 (L) mixed respectively with ACA4 and ACA5 (2 wt % of coalescing agents were used). Controls used were butyl carbitol (BC) and texanol ester alcohol. As shown, there is a reduction in the MFFT by using ACAs designed in accordance with various embodiments disclosed herein. Commercial latex 3 used as a comparative example is ECO338.

[0155] FIG. 6 is a schematic diagram for illustrating the method used for film formation from the amine based coalescing agents designed in accordance with various embodiments disclosed herein (using ACA4 as an example) and latex polymer (using acrylate latex e.g., IRS-129 as an example). After film formation, the film is air dried followed by accelerated evaporation at 110° C. Traditional coalescing agents like 1-Phenoxy-2-propanol (PPH) and Texanol were used as control.

[0156] FIG. 7A is a .sup.1H NMR spectrum of a latex polymer (namely poly(methyl methacrylate)/poly(butyl methacrylate)/poly(methacrylic acid) (PMMA/PBMA/PMAA)) in the absence of any coalescing agent.

[0157] FIG. 7B shows .sup.1H NMR spectra of a latex polymer (PMMA/PBMA/PMAA) in the presence of comparative example PPH (i) before heating; (ii) after drying/heating at 110° C. for 2 days; and (iii) after drying/heating at 110° C. for 4 days. PPH disappeared from coating film after heating.

[0158] FIG. 7C shows .sup.1H NMR spectra of a latex polymer (PMMA/PBMA/PMAA) in the presence of ACA4 (i) before heating; (ii) after drying/heating at 110° C. for 2 days; and (iii) after drying/heating at 110° C. for 4 days. ACA4 was still present and reacted (i.e. peak broadened) within the coating film even after heating.

[0159] FIG. 8 shows photographs of basic coating formulations C1 to C3 taken respectively after film formation on metal plates and after immersion in water. C1 is a basic coating formulation prepared with coalescing agent ACA4. C2 and C3 are controls. C2 is a control formulation prepared without any coalescing agent and C3 is a control formulation prepared using a commercial coalescing agent PPH. Latex (L): YS800AP (BASF); MFFT 27.2° C.; TiO.sub.2=˜ 5 wt % in wet film=˜10 wt % in dry film; PPH/ACA=2 wt % wet film; and TiO.sub.2 dispersion: SC50% using BYK154; 0.25 g of TiO.sub.2+5 g latex (SC 46.5%).

[0160] FIG. 9 shows photographs of microscopic glass slides coated with C1 formulation taken respectively (i) before UV exposure; and (ii) after 100 hours of UV exposure using Omnicure S2000. Irradiance=50 mW/m.sup.2; Exposure time=100 hrs which is equivalent to 563 hrs continuous sunlight exposure, equivalent to 56 days (10 hrs/day).

[0161] FIG. 10 shows .sup.13C NMR spectra of (i) ACA; (ii) a mixture of ACA4 and methacrylic acid (MAA); and (iii) methacrylic acid (MAA). Acid-amine interaction was clearly observed as seen by shift of peak positions.

[0162] FIG. 11 shows a photograph of the latex polymer (acrylate latex IRS-129) taken before heating. FIG. 11 also shows photographs of the latex polymer (acrylate latex IRS-129) taken after heating at 100° C. for 4 days (i); when mixed with ACA4 (ii); when mixed with PPH (iii); and when mixed with texanol ester alcohol (iv). ACA4 seemed to reduce oxidation and coloration of polymer.

EXAMPLES

[0163] Example embodiments of the disclosure will be better understood and readily apparent to one of ordinary skill in the art from the following examples, tables and if applicable, in conjunction with the figures. It should be appreciated that other modifications related to structural, and chemical changes may be made without deviating from the scope of the invention. Example embodiments are not necessarily mutually exclusive as some may be combined with one or more embodiments to form new example embodiments. The example embodiments should not be construed as limiting the scope of the disclosure.

Example 1: Features/Advantages of Amine Based Coalescing Agents

[0164]

Scheme 1. Technical features/advantages of amine based coalescing agents designed in accordance with various embodiments disclosed herein

[0165] In the following examples, the synthesis of novel amine based coalescing agents (ACAs) and their application as reactive coalescing agents (RCAs) for waterborne coatings are reported. Scheme 1 shows some of the technical features/advantages of amine based coalescing agents designed in accordance with various embodiments disclosed herein.

[0166] Advantageously, these ACAs compound designed in accordance with various embodiments disclosed herein are easy to synthesize via Michael addition reaction. These molecules also possess all the necessary/required characteristics/properties of conventional coalescing agents (CAs).

[0167] Embodiments of these compounds have boiling points >250° C. and are therefore termed as “no-VOC” (according to European and Canadian regulations, e.g., European Union directive 2014/42/EC). Volatility of these amine based coalescing agents are lower than commercial coalescing agents (CAs) in the art, therefore showing their potential for use in producing low/no-VOC waterborne coating formulations.

[0168] These amine based coalescing agents are reactive (therefore regarded as reactive coalescing agents (RCAs)) towards acid functionality, which is an important component of most waterborne coatings. Due to its Lewis basicity, the amine based coalescing agents interact with —COOH groups present within (almost all) latex binder polymer after drying and do not get released into the environment. As will be shown in the following examples, the ACA/—COOH interaction and no-release characteristics were confirmed by NMR spectroscopy.

[0169] There is no or substantially no coloration when formulated in waterborne coatings even though the coalescing agents designed in accordance with various embodiments disclosed herein are amine based compounds. As will be appreciated by a person skilled in the art, amine based compounds are typically colored.

[0170] Novel dual reactive coalescing agents were also successfully designed and synthesized via incorporation of reactive vinyl group(s) to these structures.

[0171] Even more advantageously, the amine based coalescing agents designed in accordance with various embodiments disclosed herein can be easily and readily used/adopted in industrial applications via an “additive based” approach. The ACAs can be added directly to the formulation of commercial coatings. There is no need to change the core formulation (such as latex type or pigments etc). Coating formulations can be prepared by simply adding the amine based coalescing agents in replacement of commercial/traditional coalescing agents. In summary, the amine based coalescing agents designed in accordance with various embodiments disclosed herein are no-VOC amine based coalescing agents that can be used in the formulation of no/low-VOC (preferentially waterborne) coatings by simply replacing currently used coalescing agents (and without changing major coating components).

Example 2: Operation and Interactions of Amine Based Coalescing Agents

[0172] FIG. 1 is a schematic diagram 100 for illustrating the operation and interactions of amine based coalescing agents designed in accordance with various embodiments disclosed herein with a polymer during/upon drying at a molecular level.

[0173] As shown in the schematic diagram 100, amine based coalescing agent 102 is mixed with a polymer containing —COOH group(s), for e.g., latex polymer 104. At step 106, during/upon drying, the amine based coalescing agent 102 reacts with the latex polymer 104 via acid-amine ionic interaction. The reaction is a triggerless one, i.e. the reaction proceeds in the absence of a separate/external chemical/physical trigger or stimulus (for e.g. metal catalyst and/or oxygen and/or UV light and/or initiator). Once the drying process is completed, a coating layer (not shown in FIG. 1) is formed which comprises amine based coalescing agent 102 chemically coupled to latex polymer 104 and becoming an integral and permanent part of the coating. It will be appreciated that the reactive amine based coalescing agents possess the characteristics as conventional coalescing agents (and also behave/act as conventional coalescing agents) until the coating formulation is dried to form a coating layer.

[0174] FIG. 2 is a schematic diagram 200 for illustrating the operation and interactions of amine based coalescing agents designed in accordance with various embodiments disclosed herein with a polymer during/upon drying at a material/coatings level.

[0175] As shown in the schematic diagram 200, at step 202, amine based coalescing agents 204a are added to a polymer in water, for e.g., latex particles 206a to form a dispersion 208. The dispersion 208 comprises amine based coalescing agents 204b dispersed with/in latex particles 206b. At step 210, once the drying process is completed, a dried coating layer 212 comprising the amine based coalescing agents 204c chemically coupled to latex polymer 206c is formed on a substrate 214.

[0176] The amine based coalescing agents designed in accordance with various embodiments disclosed herein may also comprise dual functionality.

[0177] FIG. 3 is a schematic diagram 300 for illustrating the operation and interactions of amine based coalescing agents (having dual functionality) with a polymer containing —COOH group(s) on aging at a molecular level in accordance with various embodiments disclosed herein.

[0178] As shown in the schematic diagram 300, the amine based coalescing agent 302 comprises dual functionality/reactivity and is capable of interacting/coupling with a polymer via at least one of an ionic interaction/coupling or a covalent interaction/coupling (e.g., polymerization such as free radical addition polymerization). Dual functional amine based coalescing agent 302 comprises a first functional group (i.e. amine group (—NR.sub.2)) 302a and a second functional group (e.g., vinyl group (C═C)) 302b.

[0179] FIG. 3 shows a coating layer 306 which comprises the amine group (—NR.sub.2) 302a of the coalescing agent chemically coupled to the carboxylic acid group (—COOH) 304a of a polymer 304 via acid-amine ionic interaction. At step 308, on aging of the coating layer, free radical(s) 304b and 304c are produced and the vinyl group (C═C)) 302b of the coalescing agent undergoes free radical reaction or addition polymerization step 310, thereby forming a network wherein the amine based coalescing agent 302 is buried permanently.

Example 3: Synthesis and Characterization of Amine Based Coalescing Agents

[0180] Amine based reactive coalescing agents were synthesized via an atom efficient aza-Michael addition reaction of secondary amine to different acrylate/acrylamide monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, .sup.nbutyl acrylate, and N-hydroxyethyl acrylamide etc (Table 1 and Scheme 2). The reactions were carried out neat or in water (in some cases, in the presence of 10% ceric ammonium nitrate (CAN) catalyst) at room temperature (RT)-80° C. to yield 80% to 95% conversion. Finally, the ACAs were purified by column chromatography and characterized by .sup.1H-NMR and .sup.13C-NMR spectroscopy, and elemental microanalysis (as will be shown in Examples 3.1 to 3.5). Other characterizations include determination of boiling point, volatility (% wt loss when heated at 110±5° C. for 1 hour as per USA EPA 24 method), and plasticizing effect, i.e. reduction of minimum film formation temperature (MFFT) of commercial latices.

TABLE-US-00001 TABLE 1 General structure of different ACAs designed in accordance with various embodiments disclosed herein General Structure: [00009] ACA Water X R Example Solubility X = O R = —CH.sub.2—CH.sub.2—OH ACA4   <0.06% R = —CH.sub.2—CH(CH.sub.3)—OH ACA5  <0.012% R = —CH.sub.2—CH(C.sub.2H.sub.5)—(CH.sub.2).sub.3—CH.sub.3 ACA6  R = —(CH.sub.2).sub.3—CH.sub.3 ACA7  R = —(CH.sub.2—CH.sub.2—O).sub.2—CH.sub.2—CH.sub.3 ACA16 R = —CH.sub.2—CH.sub.2—OCO—C(CH.sub.3)═CH.sub.2 ACA15 R = —CH.sub.2—CH(OH)—CH.sub.2—OCO—C(CH.sub.3)═CH.sub.2 ACA13 X = NH R = —CH.sub.2—CH.sub.2—OH ACA8 

##STR00010##

3.1. Synthesis of ACA4, ACA5, ACA6 and ACA7

[0181] ##STR00011##

[0182] Dibenzylamine (2 mL, 10.4 mmol) was added to 50 mL single neck RB flask at atmospheric conditions followed by slow addition of 2-hydroxy ethyl acrylate (1.31 mL, 11.4 mmol) compound at RT. The reaction continued for 30 hours at 50° C. and .sup.1H-NMR shows monomer conversion of 88.2%. The reaction mixture was stirred in water for 30 min to remove any excess 2-hydroxy ethyl acrylate monomer and extracted with CHCl.sub.3 solvent followed by rotary evaporator and vacuum dried at RT yielding 78% of compound and further purified by column chromatography (just to ensure purity) yields light pale yellowish color viscous oil. .sup.1H NMR (400 MHz, Chloroform-d) δ 7.39-7.38 (d), 7.33-7.29 (t), 7.24-7.21 (t), 4.10-4.07 (t), 3.76-3.73 (t), 3.69-3.65 (t), 3.60 (s), 2.81-2.77 (dd), 2.56-2.52 (t); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 173.41, 141.15, 130.26, 129.64, 128.35, 67.22, 61.41, 59.30, 50.61, 33.79; b.p. 292-297° C.

[0183] ACA5, ACA6 and ACA7 were prepared in a similar way as ACA4. Characterization details of these compounds are given below.

[0184] ACA5: .sup.1H NMR (400 MHz, Chloroform-d) δ 7.40-7.38 (d), 7.33-7.29 (t), 7.24-7.21 (t), 3.94-3.88 (m), 3.77 (b), 3.60 (s), 2.82-2.77 (dd), 2.57-2.50 (m), 1.17-1.16 (d), 1.11-1.10 (d); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 173.27, 173.08, 141.12, 130.27, 129.65, 128.36, 72.90, 70.69, 66.38, 66.06, 59.28, 50.69, 50.60, 33.96, 33.76, 20.71, 17.33; Calcd: C, 73.37; H, 7.70; N, 4.28. Found: C, 73.18; H, 7.81; N, 4.34; b.p. 292-296° C.

[0185] ACA6: .sup.1H NMR (400 MHz, Chloroform-d) δ 7.40-7.38 (d), 7.30-7.33 (t), 7.21-7.25 (t), 3.96-3.94 (m), 3.60 (s), 2.87 (s), 2.84 (s), 2.81-2.77 (t), 2.55-2.51 (t), 1.52 (m), 1.28 (m), 0.89-0.85 (m); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 173.23, 140.92, 130.09, 129.50, 128.22, 67.37, 59.08, 50.45, 40.12, 33.66, 31.63, 24.94, 24.11, 14.82, 11.80; Calcd: C, 78.7; H, 9.25; N, 3.67). Found: C, 78.23; H, 9.20; N, 3.64; b.p. 354-364° C.

[0186] ACA7: .sup.1H NMR (400 MHz, Chloroform-d) δ 7.38-7.36 (d), 7.32-7.29 (t), 7.24-7.20 (t), 3.99 (t), 3.58 (s), 2.86 (s), 2.83 (s), 2.77 (t), 2.51 (t), 1.56-1.49 (m), 1.38-1.28 (m), 0.91-0.87 (t); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 173.16, 140.97, 130.09, 129.48, 128.20, 64.94, 59.09, 50.46, 33.68, 31.93, 20.27, 14.48; Calcd: C, 77.50; H, 8.36; N, 4.30. Found: C, 77.80; H, 8.32; N, 4.31; b.p. 342-350° C.

3.2. Synthesis of ACA13

[0187] ##STR00012##

[0188] To dibenzylamine (6 g, 30.41 mmol) and 3-(Acryloyloxy)-2-hydroxypropyl methacrylate (5.21 g, 24.3 mmol) dissolved in 50 mL of ACN:H.sub.2O (9:1) was added ceric ammonium nitrite (0.5 g, 0.9 mmol) and stirred at ambient for 16 hours. The reaction mixture was diluted with diethyl ether and washed with water and ether layer was concentrated. Product purified in 20% EtOAC/Pet-ether to give the desired product as a light brown viscous oil in 40% yield; .sup.1H NMR (400 MHz, Chloroform-d) δ 7.31 (m, 10H), 6.16 (t, J=1.2 Hz, 1H), 5.64 (t, J=1.6 Hz, 1H), 4.39-3.95 (m, 5H), 3.61 (s, 4H), 2.84 (t, J=7.0 Hz, 2H), 2.57 (t, J=7.0 Hz, 2H), 2.24-1.84 (m, 3H). .sup.13C NMR (101 MHz, CDCl.sub.3) δ 172.50, 167.32, 139.03, 135.81, 128.88, 128.24, 127.04, 126.30, 68.22, 65.28, 58.17, 49.17, 32.77, 18.29; b.p. 290-300° C. (gel point).

3.3. Synthesis of ACA15

[0189] ##STR00013##

[0190] To ACA4 (2.8 g, 8.93 mmol) and methacrylic anhydride (1.45 g, 9.38 mmol) in dichloromethane (DCM) was added trimethylamine (0.9 g, 9.83 mmol) and 4-dimethylaminopyridine (DMAP) (0.06 g, 0.5 mmol), and the reaction mixture was stirred at ambient for 4 hours. The reaction mixture was diluted with DCM and washed with water. DCM layer was concentrated and reaction mixture was purified by flash chromatography in 30% EtOAC/Pet-ether to give the desired product as light brown semi solid in 82% yield. .sup.1H NMR (400 MHz, Chloroform-d) δ 7.36-7.11 (m, 10H), 6.02 (dd, J=1.6, 1.0 Hz, 1H), 5.62-5.39 (m, 1H), 4.21 (s, 4H), 3.52 (s, 4H), 2.76 (t, J=7.2 Hz, 2H), 2.46 (t, J=7.2 Hz, 2H), 1.86 (dd, J=1.6, 1.0 Hz, 3H); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 172.26, 167.08, 135.90, 128.77, 128.20, 126.97, 126.00, 62.37, 62.01, 58.09, 49.14, 32.69, 18.24. m.p. 50° C., b.p. 251-254° C.

3.4. Synthesis of ACA16

[0191] ##STR00014##

[0192] Dibenzylamine (4.764 g, 24.15 mmol) and di(ethylene glycol) ethyl ether acrylate (5.0 g, 26.56 mmol) were mixed in a 50 mL single neck RB flask at atmospheric conditions. The mixture was then heated at 80° C. for 4 days to have 90% conversion with respect to (wrt) vinyl group. The product mixture was then stirred with water (2×50 mL), centrifuged and dried in a vacuum oven at 50° C. to yield light brown liquid. Yield 5.82 g, 62.5% (un-optimized). .sup.1H NMR (400 MHz, Chloroform-d) δ 7.36-7.5 (m), 4.36 (t), 3.64-3.74 (m), 2.97 (t), 2.69 (t), 1.36 (t); .sup.13C NMR (101 MHz, CDCl.sub.3) δ 172.5, 139.3, 128.7, 128.1, 126.9, 70.6, 69.7, 69.0, 66.7, 58.0, 49.1, 32.7, 15.2; b.p. 348-355° C.

3.5. Characterization of ACA4 to ACA8, ACA13, ACA15 and ACA16

[0193] Characterization studies were performed on the ACA examples to determine their boiling points and volatility (% wt loss when heated at 110±5° C. for 1 hour as per USA EPA 24 method). The results obtained are shown in Table 2.

TABLE-US-00002 TABLE 2 Structure of ACAs, boiling point (b.p.) and volatility results b.p. Volatility, % wt No. Code Structure (° C.) loss@110° C., 1 h 1 ACA4  [00015] 293 3.6 2 ACA5  [00016] 294 1.6 3 ACA6  [00017] 358 3.0 4 ACA7  [00018] 346 0.1 5 ACA8  [00019] 267 8.9 6 ACA16 [00020] 350 9.8 7 ACA15 [00021] 254 9.5 8 ACA13 [00022] 298 9.7

[0194] In Table 1, ACA15 and ACA13 have dual functionality and/or are dual reactive molecules. The boiling points of ACA4, ACA5, ACA6 and ACA7 are shown in FIG. 4A alongside with butyl carbitol (BC) and texanol which were used as comparison/control. The volatility of ACA4, ACA5, ACA6 and ACA7 are shown in FIG. 4B alongside with butyl carbitol (BC) and texanol which were used as comparison/control.

Example 4: Formulation and Evaluation of Amine Based Coalescing Agents

[0195] 4.1. Minimum Film Formation Temperature (MFFT) of Commercial Latices Mixed with Amine Based Coalescing Agents

[0196] ACAs were mixed (2 wt %) with three different commercial waterborne latices (BASF 538A, Nippon N-2398 and ECO338) and minimum film formation temperature (MFFT) of these lattices were determined using MFFT recorder (MFFT-90-MFFT Bar) according to ASTM D2354. The results are presented in FIG. 5A (using BASF 538A as latex (L)), FIG. 5B (using Nippon N-2398 as latex (L)) and FIG. 5C (using ECO338 as latex (L) respectively.

[0197] As shown in FIG. 5A to 5C, the MFFT of the commercial latices were reduced by using ACAs (2 wt %). It is therefore shown that the ACAs designed in accordance with various embodiments disclosed herein have similar or sometimes even better efficiency as compared with the commercial controls (namely butyl carbitol (BC) and Texanol ester alcohol). MFFT is the lowest temperature at which a latex will uniformly coalesce when laid on a substrate as a thin film and produce smooth homogeneous crack free coating film. An accurate MFFT value allows formulation of coatings that cure correctly under a specified application conditions or environment.

4.2. Mixing of ACA4 with —COOH Containing Latex for Reactivity Study Evaluated with NMR Spectroscopy

[0198] Using ACA4 as an example, amine based coalescing agents designed in accordance with various embodiments disclosed herein were mixed with —COOH containing latex for reactivity study and evaluated with NMR spectroscopy.

4.2.1. Synthesis of Latex (IRS-129)

[0199] In a 250 mL jacketed reactor was charged with 125 g of distilled water, 2.0 g of sodium dodecyl sulphate, 885 mg of ammonium persulfate, and 650 mg of NaHCO.sub.3 and purged with argon for 30 min at room temperature before the reaction. The monomer mixture (Butyl methacrylate (.sup.nBMA) 46.26 g, methyl methacrylate (MMA) 26.04 g, and methacrylic acid (MAA) 2.66 g) was degassed for 30 min at room temperature and added slowly for 3 hrs (=27 mL/hr). The glass reactor was connected to Lauda water heater and the reaction was continued for 6 hrs at 65° C. Finally, the reaction mixture was heated to 80° C. for 1 hr to complete the polymerization reaction. After the reaction, the latex sample pH was adjusted to (≈10.0) using the NH.sub.3(aq). The latex particle size was measured using Malvern DLS instrument (Z.sub.ave=63.0 nm, PDI=0.075) (Total solid content=39.0 wt %). Expected copolymer structure is Poly(BMA.sub.52.8-co-MMA.sub.42.2-co-MAA.sub.5).

4.2.2. Blending ACA4 with Latex IRS-129, Film Formation and Accelerated Release Study

[0200] FIG. 6 is a schematic diagram for illustrating the method used for film formation from the amine based coalescing agents designed in accordance with various embodiments disclosed herein (using ACA4 as an example) and latex polymer (using acrylate latex e.g., IRS-129 as an example). Traditional coalescing agents like 1-Phenoxy-2-propanol (PPH) and Texanol were used as control.

[0201] At first, ACA4 (2 wt % with respect to latex) was first blended with IRS-129 latex (containing —COOH groups) using dispermat (LC75-E) and the mixture was allowed to dry at room temperature for 2 days. Then, the polymer film was grounded to make powder and then heated at 110° C. in a convection oven, i.e. accelerated evaporation (as illustrated in FIG. 6). Accelerated evaporation was used in this study instead as natural release is time consuming and gas analysis is difficult.

[0202] Samples were collected time to time, dissolved in NMR solvent and analyzed by .sup.1H NMR spectroscopy (with 25 mg of sample, 0.8 mL of CDCl.sub.3, and 25 μL of DMF/CDCl.sub.3 as internal standard). High boiling commercial coalescing agent, 1-Phenoxy-2-propanol (PPH) (b.p. 243° C.) was used as control.

[0203] The .sup.1H NMR results are presented in FIG. 7A to FIG. 7C. It can be clearly observed that PPH is completely evaporated out from the polymer after 2 days of heating (see FIG. 7B(ii)). However, ACA4 remain present even after 4 days of heating (see FIG. 7C(iii)) and is quantitative as polymer sample before heating (see FIG. 7C(i)). However, the most interesting result is the appearance of the aromatic peak belonging to ACA4, which became broader unlike the sharper appearance observed for the sample before heating. It is believed that the broader appearance of the ACA4 aromatic peaks signifies the stronger interaction in between ACA4 and polymer, which made the ACA4 as an integral part of the polymer. This confirmed the low volatility and reactivity of ACA4 and its application as reactive coalescing agents.

4.3. Formulation of Coating Using ACA4, TiO.SUB.2 .and a Commercial Latex, Film Formation and Film Evaluation

[0204] A basic coating formulation (see C1, FIG. 8) was developed using a commercial latex (YS800AP from BASF, MFFT 27.2° C.), TiO.sub.2 (rutile, Tronox CR-826) (5 wt % in wet film) and ACA4 (2 wt %) using dispermat (Dispermat LC75-E). Two control formulations, first one, without using any coalescing agent (C2) and, second one, using a commercial coalescing agent PPH (2 wt %) (C3) were also produced in exactly the similar procedure as for ACA4. These coatings were then coated on metal plates, air dried and film formation was observed.

The following observations were noted for formulation C1 after coating: [0205] No visible change of pH [0206] No coloration and nice film formation [0207] No stickiness

[0208] The formulation C2 cracked and did not make good film as expected (as MFFT is higher than RT), whereas formulation C1 produced uniform non tacky film similar to formulation C3. The coated films from C1 and C3 were then immersed in water for 2 days. Both the films did not show any evidence of delamination, dissolution, blistering and stickiness.

4.4. UV Exposure of C1 Formulation

[0209] A few microscopic glass slides were coated with C1 formulation (using ACA4) and dried at room temperature before exposing to high energy UV light (Omnicure S2000 with light guide, 250-450 nm, irradiance 50 mW/cm.sup.2) for 100 hrs (equivalent to 56 day outdoor exposure considering 10 hrs of sunlight available each day).

[0210] No sign of discoloration or color development was observed as can be seen in the photographs shown in FIG. 9(i) and FIG. 9(ii).

4.5. Study of ACA4-COOH Interactions

[0211] ACA4-COOH interactions were studied with .sup.1H NMR and .sup.13C NMR spectroscopy using small molecules. In this study, methacrylic acid (MAA) was used.

##STR00023##

[0212] .sup.13C NMR spectra obtained for ACA4, MAA and a mixture of ACA4 and MAA are shown respectively in FIG. 10. Acid-amine interaction was clearly observed as seen by shift of peak positions.

4.6. Stabilization of Polymer by ACA4

[0213] FIG. 11 shows a photograph of the latex polymer (acrylate latex IRS-129) taken before heating. FIG. 11 also shows photographs of the latex polymer (acrylate latex IRS-129) taken after heating at 100° C. for 4 days (i); when mixed with ACA4 (ii); when mixed with PPH (iii); and when mixed with texanol ester alcohol (iv).

[0214] As can be seen from the photographs obtained after heating, only photograph (iii) showed a stable sample, i.e. the same appearance as that of the original latex polymer captured prior to heating. Therefore, it can be concluded that ACA4 helps to stabilise or reduce oxidation/coloration of the polymer.

Example 5: Summary

[0215] The present disclosure provides coalescing agent for a coating formulation that is substantially free from volatile organic compounds (VOCs), a coating composition and a coating layer. Embodiments of the reactive coalescing agent, coating composition and coating layer disclosed herein possess one or more of the following properties/features: [0216] (1) Color: Although the amine based coalescing agents disclosed herein are light yellow/brown in color, there is no coloration when prepared in solution or when formulated in coating. [0217] (2) Basicity: As the amine content in the amine based coalescing agents disclosed herein is very low as compared to the overall size and molecular weight of the molecule, the amine based coalescing agents do not influence pH much. In fact, there is no change in pH when the amine based coalescing agents disclosed herein was formulated with the latex. It may be noted that waterborne latices have a basic pH of 8-9. [0218] (3) Odor: No odor [0219] (4) Thermal Stability: Amine based coalescing agents disclosed herein even reduce discolouration of latex polymer [0220] (5) UV stability: Did not show any discoloration on UV exposure

[0221] It will be appreciated by a person skilled in the art that other variations and/or modifications may be made to the embodiments disclosed herein without departing from the spirit or scope of the disclosure as broadly described. For example, in the description herein, features of different exemplary embodiments may be mixed, combined, interchanged, incorporated, adopted, modified, included etc. or the like across different exemplary embodiments. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.