COMPOSITION, FILM, KIT, COATED SUBSTRATE, AND RELATED METHODS THEREOF

Abstract

There is provided a composition comprising: (i) a polymer; (ii) inorganic particles; and (iii) aqueous medium, wherein the inorganic particles are adapted to interact with the polymer to cause an increase in glass transition temperature (Tg) during film formation of the composition. Also provided are a film, a method of preparing said film, a kit and a coated substrate.

Claims

1. A composition comprising: (i) a polymer; (ii) inorganic particles; and (iii) aqueous medium, wherein the inorganic particles are adapted to interact with the polymer to cause an increase in glass transition temperature (Tg) during film formation of the composition.

2. The composition of claim 1, wherein the increase in Tg during film formation of the composition is due to a nanoconfinement effect.

3. The composition of claim 1, wherein the increase in Tg from Tg of the polymer to Tg of the film comprises a temperature increase in an amount of at least 10° C.

4. The composition of claim 1, wherein the interactions involving the inorganic particles and the polymer in the aqueous medium comprise non-covalent interactions.

5. The composition of claim 1, wherein the composition is substantially devoid of a plasticizer.

6. The composition of claim 1, wherein the composition is substantially devoid of small organic compounds (SOC) and/or volatile organic compounds (VOC).

7. The composition of claim 1, wherein the inorganic particles comprise inorganic nanoparticles having an average size that is no more than 200 nm.

8. The composition of claim 7, wherein the inorganic nanoparticles are selected from the group consisting of silicon dioxide, titanium dioxide, clay, nanocrystalline cellulose and lignin powders.

9. The composition of claim 1, wherein the polymer comprises one or more types of monomers selected from styrene; acrylic acid; methacrylic acid; maleic acid; itaconic acid; acrylonitrile; methacrylonitrile; butadiene; vinylidene chloride; vinyl acetate; and derivatives thereof.

10. The composition of claim 9, wherein the acrylic acid derivative thereof is selected from methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate (2EHA) and N,N,dimethylacrylamide (NNDMA); and the methacrylic acid derivative thereof is selected from methyl methacrylate (MMA) and (hydroxyethyl) methacrylate (HEMA).

11. The composition of claim 1, wherein the aqueous medium is in an amount of from 30 wt % to 60 wt % of the composition.

12. The composition of claim 1, wherein the inorganic particles are in the amount of from 0.05 wt % to 5.0 wt % of the composition.

13. The composition of claim 1, wherein the polymer is in an amount of from 10 wt % to 40 wt % of the composition.

14. The composition of claim 1, wherein the composition is a paint composition and further comprises one or more of the following: pigment, filler, wetting agent, thickening agent, base, anti-foaming agent and dispersing agent.

15-20. (canceled)

21. A coated substrate comprising: a film disposed on/over a surface of the substrate, the film formed by curing the composition of claim 1 on/over the surface of the substrate, wherein the inorganic particles are adapted to interact with the polymer in the composition to cause an increase in glass transition temperature (Tg) during film formation.

22. The coated substrate according to claim 21, wherein the film has one or more of the following properties: odourless, non-tacky, non-sticky, excellent resistance to scrub, excellent resistance to abrasion, excellent resistance to washing, low or zero wetting, low water vapour transmission rate under dry conditions, chemically and/or physically stable, excellent resistance towards natural exposure/weathering.

23. The coated substrate according to claim 21, wherein the film has a glass transition temperature in the range of from 15.0° C. to 40.0° C.

24. The method of preparing a coated substrate, the method comprising: applying the composition of claim 1 on/over a substrate; and curing the composition to form a film on/over the substrate, wherein the inorganic particles are adapted to interact with the polymer to cause an increase in glass transition temperature (Tg) during film formation of the composition.

25. The method according to claim 24, wherein prior to the applying step, the method comprises: mixing inorganic particles, aqueous medium and optionally one or more of pigment, filler, wetting agent, thickening agent, base, anti-foaming agent, and dispersing agent, to form a mill base; and mixing said mill base with a polymer to form the composition.

26. The method according to claim 25, wherein the step of mixing to form a mill base comprises stirring the mixture until the particle size is less than 50 μm as determined by a Hegman gauge.

Description

BRIEF DESCRIPTION OF FIGURES

[0100] FIG. 1 is a graph showing changes in the glass transition temperature (Tg) with time for a plasticizer-based system in a conventional approach, where a plasticizer is working as a solvent.

[0101] FIG. 2 is a graph showing changes in the glass transition temperature (Tg) with time for a plasticizer-free system designed in accordance with various embodiments disclosed herein.

[0102] FIG. 3A is a graph showing the particle size (d) in nm of exemplary latex particles designed in accordance with various embodiments disclosed herein, as measured by dynamic light scattering (DLS). Em3-80deg is the sample name of the latex used in the experiment. 4, 5 and 6 represents three runs of the DLS experiments.

[0103] FIG. 3B is a graph showing the zeta potential measurement in mV of exemplary latex particles designed in accordance with various embodiments disclosed herein, as measured by dynamic light scattering (DLS). Emulsions 11, 12 and 13 represent repetition of zeta potential measurements of the latex sample named Em3-80deg.

[0104] FIG. 4A and FIG. 4B show cryo-transmission electron microscopic (Cryo-TEM) images of exemplary latex particles designed in accordance with various embodiments disclosed herein. The scale bar represents 0.2 μm. FIG. 4C shows a scanning electron microscopic (SEM) image of exemplary latex particles designed in accordance with various embodiments disclosed herein. The scale bar represents 100 nm.

[0105] FIG. 5A is a graph showing the glass transition temperature (Tg) of no. 1 latex and nanocomposites loaded with varying wt % of SiO.sub.2. The average size of the fumed silica used is 7 nm.

[0106] FIG. 5B is a graph showing the glass transition temperature (Tg) of no. 1 latex and nanocomposites loaded with varying wt % of SiO.sub.2. The average size of the fumed silica used is 200 nm.

[0107] FIG. 6 is a graph showing the glass transition temperature (Tg) as a function of SiO.sub.2 loading for a fumed silica:poly(vinyl acetate) (PVA) system, as measured with differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA).

[0108] FIG. 7 is a graph showing the extent of hydrogen bonding as a function of SiO.sub.2 loading for a fumed silica:PVA system.

[0109] FIG. 8 shows photographs of surface coatings that have undergone wet abrasion scrub resistance tests. FIG. 8A shows surfaces coated with paint formulation F7H and F11H. FIG. 8B shows surfaces coated with paint formulation F7L and F11L.

[0110] FIG. 9 show photographs of paint film (A) containing F7L and paint film (B) containing F11L after a water droplet was put onto both films. After wiping off the water after 15 minutes, there was no water mark observed for both paint film (C) containing F7L and paint film (D) containing F11L

[0111] FIG. 10 show photographs obtained from print resistance test of paint formulations. FIG. 10A shows ASTM standard cotton. FIG. 10B shows ASTM standard cotton imprinted on F11L. FIG. 10C shows ASTM standard cotton imprinted on F11H. FIG. 10D shows the cotton being removed after the test, FIG. 10E and FIG. 10F show that no impression is found on F11L and F11H respectively.

[0112] FIG. 11 is a schematic flowchart 100 for illustrating the experiment set-up for testing the permeability of the paint coatings designed in accordance with various embodiments disclosed herein.

[0113] FIG. 12 is a graph showing mass against time for 10 cm.sup.2 Nippon Weatherbond and 25 cm.sup.2 Nippon Roofguard permeability films.

[0114] FIG. 13 is a graph showing mass against time for 10 cm.sup.2 Nippon Aqua Bodelac and 25 cm.sup.2 Nippon Weatherbond permeability films.

[0115] FIG. 14 is a graph showing mass against time for Formulation F11L permeability film.

[0116] FIG. 15 is a photograph of weather/exposure racks set up at an experimental site in Nanyang Technological University (NTU) used for testing natural exposure.

[0117] FIG. 16 shows photographs obtained from the weathering tests performed on formulations designed in accordance with various embodiments disclosed herein.

[0118] FIG. 17 shows an experimental set up 200 for performing emulsion polymerisation 202 during latex synthesis.

[0119] FIG. 18 shows a schematic diagram 300 for illustrating emulsion polymerisation.

[0120] FIG. 19 shows a transmission electron microscopic (TEM) image of silica used in the method designed in accordance with various embodiments disclosed herein. The scale bar represents 20 nm.

[0121] FIG. 20 is a graph showing the glass transition temperature (Tg) of exemplary latex designed in accordance with various embodiments disclosed herein and nanocomposites loaded with varying wt % of SiO.sub.2 nanoparticles.

[0122] FIG. 21 shows a schematic diagram 400 for illustrating a method of preparing paint formulation designed in accordance with various embodiments disclosed herein.

[0123] FIG. 22 shows photographs of films formed by the paint formulations designed in accordance with various embodiments disclosed herein.

[0124] FIG. 23 shows photographs of surface coatings that have undergone wet abrasion scrub resistance tests. FIG. 23A shows surface coated with blank. FIG. 23B shows surface coated with an ICES plasticizer free paint formulation designed in accordance with various embodiments disclosed herein (hereinafter referred to as “iPF Paint”).

[0125] FIG. 24 shows photographs of paint films that have undergone 72 hours of QUV exposure test. FIG. 24A shows Nippon Aqua Bodelac paint film. FIG. 24B shows Dulux Gloss paint film.

[0126] FIG. 25 shows photographs of paint films before and after 72 hours of QUV exposure test. FIG. 25A shows blank. FIG. 25B shows ICES plasticizer free paint formulation designed in accordance with various embodiments disclosed herein (hereinafter referred to as “iPF Paint”). FIG. 25C shows ICES plasticizer free colour paint formulation designed in accordance with various embodiments disclosed herein (hereinafter referred to as “iPF Colour Paint”).

[0127] FIG. 26 shows photographs of paint films after 3 months of natural exposure/weathering. FIG. 26A shows Nippon Aqua Bodelac paint film. FIG. 26B shows Dulux Gloss paint film.

[0128] FIG. 27 shows photographs of paint films on concrete and metal substrates after 3 months of natural exposure/weathering. FIG. 27A shows blank. FIG. 27B shows ICES plasticizer free paint formulation designed in accordance with various embodiments disclosed herein (hereinafter referred to as “iPF Paint”).

[0129] FIG. 28 shows photographs obtained from the weathering tests performed on commercial formulations and formulations designed in accordance with various embodiments disclosed herein. FIG. 28A shows Dulux Gloss. FIG. 28B shows Aqua Bodelac. FIG. 28C and FIG. 28D shows F1 with and without primer respectively. FIG. 28E shows F2 with primer. The primer used was commercial primer Nippon Bodelac 9000 Undercoat. Normally, the makeup of these primers are 20-30% polymer, 60-80% water and 2-5% additive agents. It will be appreciated that latex dispersion may also be used as the primer.

EXAMPLES

[0130] 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.

[0131] In the following examples, the inventors show that embodiments of the presently disclosed method are capable of synthesizing small organic compounds (SOC) and/or plasticizer free formulations by using interaction between presently designed polymer binders in waterborne coating and commercially available nano-additives.

[0132] As will be shown in the following examples, formulations designed in accordance with various embodiments disclosed herein are designed and created using nanoconfinement effect. This concept is somewhat different from the evaporative effect used in plasticizer-based system of conventional methods which is illustrated in FIG. 1.

[0133] FIG. 1 shows a glass transition temperature (Tg) vs. time graph for a plasticizer-based system in conventional methods. In such conventional methods, the plasticizer is typically added which will reduce the Tg to promote coalescence. When film formation is over, the plasticizer will evaporate, leading to a Tg jump. It will be appreciated by a person skilled in the art that this conventional technology is almost like a modified form of solvent based paint where the plasticizer is working as solvent. Therefore, as can be seen, the use of SOCs or volatile organic compounds (VOCs) in the form of plasticizers remains necessary in current methods used to prepare coating formulations.

[0134] On the contrary, the concept/underlying principle of using the nanoconfinement effect for the formulations designed in accordance with various embodiments disclosed herein is explained in FIG. 2.

[0135] Referring to FIG. 2, Tg of the latex designed in accordance with various embodiments disclosed herein is low before film formation. Due to nanoconfinement effect, Tg increases upon film formation. For example, a low Tg binder may be used which can undergo coalescence on evaporation of water. Physical interaction(s) between binder and inorganics may cause the Tg jump to provide a non-tacky film. Importantly, the idea of the presently disclosed method is not based on any evaporative solvent. The presently disclosed method could, therefore, provide a breakthrough technology for designing SOC and/or plasticizer free water-based paints and/or polymer films.

Example 1: Latex Synthesis

1.1. Synthesis Procedure of Latex

[0136] The general procedure for synthesizing latex in accordance with various embodiments disclosed herein include: mixing a mixture containing two or more monomers with a surfactant, buffer and initiator.

[0137] Total emulsion to be made is 200 mL with solid content 30%. Total monomer required is 60 mL. Table 1 shows the composition and weight of the monomer mixture used for synthesis of latex.

TABLE-US-00001 TABLE 1 Composition and Weight of Monomer Mixture Components Weight (%) Weight (g) Styrene (Sty) 26 14.37 2-ethyl hexyl acrylate (2EHA) 38 21.01 Methyl methacrylate (MMA) 30 16.58 Methacrylic acid (MAA) 6 3.32

[0138] Density of composition mixture is:

0.26×0.906 (Sty)+0.38×0.885 (2EHA)+0.3×0.936 (MMA)+0.06×1.015 (MAA)=0.92136 g/mL

[0139] (60 mL=60×0.92136=55.2816 gram monomer mixture)

[0140] In this example, sodium dodecyl sulfate (SDS) is used as the surfactant, sodium bicarbonate is used as buffer and ammonium persulfate is used as the initiator for emulsion polymerisation. 4 wt % of surfactant and 2 wt % of sodium bicarbonate with respect to the monomer mixture is first added to argon-bubbled deionized water. The mixture is stirred and heated to 70-80° C. Then pre-dissolved ammonium persulfate (APS) of 1 wt % with respect to the monomer mixture is added to the mixture, followed by feeding the monomer mixture into the solution at 0.2 mL/min The reaction is allowed to stir for 24 h to consume all the monomers. The mixture is filtered after the reaction, the dispersion is stable. The total solid content of the latex system was measured to be 31.76%.

1.2. Characterization of Latex

[0141] The latex dispersion is then measured for particle size and zeta-potential by dynamic light scattering (DLS). The characterisation results are provided in FIG. 3A and FIG. 3B respectively. As shown, the size of the latex particle is 42.98 nm. Zeta potential of the dispersion is 28.2 mV.

[0142] In addition to these characterizations, cryo-transmission electron microscopic (TEM) and scanning electron microscopic images were also taken to confirm the particle size information that is obtained from DLS, as shown in FIG. 4A, FIG. 4B and FIG. 4C.

[0143] After characterization was completed, the system was scaled up to 1 litre and used in formulations of paint.

1.3. Latex Systems Synthesized in this Example

[0144] A variety of latex systems were prepared in accordance with the procedure described above for the study. A summary of the latex systems synthesized in this example is shown in Table 2.

TABLE-US-00002 TABLE 2 Summary of Synthesized Latex Systems Solid GPC (THF) Latex content Diameter Tg (° C.) Mol. Wt. No. Composition* (wt %) (nm) Fox eq. DSC (Mw) Mw/Mn 1 Sty (26%), 2EHA (38%), 30 42 28.7 19.89 78,807 3.9 MMA (30%), MAA (6%) 2 Sty (26%), 2EHA (38%), 50 235 28.7 28.35 58,326 2.2 MMA (30%), MAA (6%) 3 Sty (26%), 2EHA (38%), 50 97 28.7 33.9 — — MMA (30%), MAA (6%) 4 Sty (26%), 2EHA (48%), 30 41 11.3 4.42 — — MMA (20%), MAA (6%) 5 Sty (26%), 2EHA (38%), 25 42 22.1 23.28 166,904 7.0 MMA (30%), HEMA (6%) 6 Sty (26%), 2EHA (38%), 35 443 22.9 — 154,347 6.1 MMA (30%), NNDMA (6%) 7 Sty (26%), 2EHA (38%), 30 72 20.1 — 186,065 7.1 MMA (30%), VA (6%) 8 Sty (28%), 2EHA (40%), 30 55 20.1 — 346,186 12.4 MMA (32%), *Sty: styrene, 2EHA: 2-ethylhexyl acrylate, MMA: methyl methacrylate, MAA: methacrylic acid, HEMA: (hydroxyethyl) methacrylate, NNDMA: N,N,dimethyl acrylamide, VA: vinyl acetate

Example 2: Tg Jump/Increase Via Nanoconfinement Effect

2.1. Proof of Concept

[0145] Proof of concept showing Tg jump was demonstrated by dynamic mechanical analysis (DMA) of films prepared by using an aqueous dispersion of the latex and various amounts of silica nanoparticles in the composite films (average size of fumed silica is 7 nm and 200 nm respectively), as provided in FIG. 5A and FIG. 5B. In this example, latex no. 1 of Table 1 is used. In the case of 7 nm fumed silica, the Tg value increased from the value of the pure latex (37.7° C.) to 48.8° C. by loading just 0.4 wt % SiO.sub.2 (FIG. 5A). In the case of 200 nm fumed silica particles, the Tg increased in a similar fashion reaching a maximum of 46.2° C. at 1.6 wt % (FIG. 5B).

[0146] Without being bound by theory, this increase in Tg values to a maximum can be attributed to the interaction of copolymer chains and the surface functionality of the SiO.sub.2 nanoparticles, which restricted the free movement of the copolymer chains. This is contrary to the common general knowledge of a technical person in the art. It is important to note that a normal practitioner in the field would be under the impression that by incorporating SiO.sub.2 nanoparticles into the latex, the free volume of the copolymer chains will be increased, therefore imparting a decrease in Tg of the composite materials. This is according to the Flory-Fox equation which shows that an increase in free volume (as represented by the empirical parameter K), for a constant molecular weight, will decrease the glass transition temperature of the composite. Hence, it is surprising that at lower wt % loadings however, this effect was not as potent due to the fact that the SiO.sub.2 nanoparticles were able to better accommodate themselves within the matrix. This ensured the maximum probability for interaction with the copolymer chains, which played a vital role in Tg increment of the nanocomposites. At further higher wt % loading of SiO.sub.2 nanoparticles, the increase in free volume of the polymer chains might be beginning to show up and restricting the interactions between the latex and SiO.sub.2 nanoparticles, which might be leading to the decreasing Tg from the maximum. As such, it can be concluded that SiO.sub.2 is able to enhance the Tg of the composite through interfacial physical interaction, allowing it to reach a maximum up to a certain extent, which vary based on the loading of nanoparticles incorporated. The Tg increase observed in the latex-silica system forms a critical part of the presently disclosed invention.

[0147] In the next example, this phenomenon was utilized to create small molecule free paint formulations.

2.2. Tg Increase in Composite Films and Hydrogen Bonding Interaction

[0148] Experiments were conducted to study the Tg increase in composite films obtained from polymer solution with dispersed silica.

[0149] FIG. 6 is a graph showing the glass transition temperature (Tg) as a function of SiO.sub.2loading for a fumed silica:poly(vinyl acetate) (PVA) system, as measured with differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA). It was observed that hydrogen bonding (H-bonding) interactions can create 10° C. to 15° C. Tg jump in different polymers.

[0150] FIG. 7 is a graph showing the extent of hydrogen bonding as a function of SiO.sub.2 loading for a fumed silica:PVA system.

[0151] It was found that hydrogen bonding interaction is the major factor influencing Tg increase.

Example 3: Paint Formulation

[0152] Paint formulations were prepared using the latex examples synthesized in Example 1. The recipe for paint formulations based on relatively high Tg latex (Examples F7H, F9H, F10H, F11H) and relatively low Tg latex (Examples F7L, F9L, F10L, F11L) is detailed in Tables 3 and 4 respectively.

[0153] In Tables 3 and 4 below, ICES Additives 1, 2 and 3 are nano silica additives, more specifically, positively charged nanosilica having an average size of 7 nm in diameter. Nouryon's Levasil CC301, which is the commercial equivalent of the nanosilica additives may also be used. Defoamer is BYK-014, thickener is RHEOBYK-7610, wetting agent is BYK-333 and dispersant is BYK-154.

TABLE-US-00003 TABLE 3 Paint Formulation using Latex No. 1 Weight (g) Components F7H F9H F10H F11H Mill base  1 Water 296 236 176 176  2 ICES Additive 1 0 0 0 50  3 ICES Additive 2 0 0.72 0 0  4 ICES Additive 3 0 0 2.1 0  5 Wetting agent 1 1 1 1  6 Thickener 0.6 0.6 0.6 0.6  7 Ammonia (25%) 2 drops 2 drops 2 drops 2 drops  8 Defoamer 0.5 0.5 0.5 0.5  9 Dispersant 2 2 2 2 10 TiO.sub.2 70 70 70 70 11 Cloisite Na.sup.+ 15 15 15 15 Let down 12 Latex No. 1 142 142 142 142

TABLE-US-00004 TABLE 4 Paint Formulation using Latex No. 4 Weight (g) Components F7L F9L F10L F11L Mill base  1 Water 296 236 176 176  2 ICES Additive 1 0 0 0 50  3 ICES Additive 2 0 0.72 0 0  4 ICES Additive 3 0 0 2.1 0  5 Wetting agent 1 1 1 1  6 Thickener 0.6 0.6 0.6 0.6  7 Ammonia (25%) 2 drops 2 drops 2 drops 2 drops  8 Defoamer 0.5 0.5 0.5 0.5  9 Dispersant 2 2 2 2 10 TiO.sub.2 70 70 70 70 11 Cloisite Na.sup.+ 15 15 15 15 Let down 12 Latex No. 4 142 142 142 142

3.1. Method of Preparing Paint Formulation

[0154] 60 mL water was added into an appropriate beaker and stirred at 400 rpm. Afterwards, wetting agent, thickener, ammonia, defoamer and dispersant were added consecutively to the water and the solution consistency changed and the mixture became slightly translucent. TiO.sub.2 pigment was slowly added to the mixture next, then clay (Cloisite Na.sup.+) was added slowly with water added in between clay addition. This is to prevent the mixture from caking due to layered structure of clay and hence longer time taken to dissolve the clay structure. The mill base mixture was stirred at 2000 rpm for 3-4 hours. The mixture was stirred until the Hegman gauge particle size is less than 30 μm. The let-down process was started by pouring the mill base mixture into the latex and stirred at 800 rpm for 3 hours.

3.2. Testing

3.2.1. Comparison with Control Paint

3.2.1.1. Wet Abrasion Scrub Resistance (Cycles)

[0155] The technique often used to test scrub, abrasion and washability resistance of paint is through an accelerated method. It also provides idea for determining wear resistance of surface coatings, and also tests the performance of cleaning compounds. Paints containing low Tg binder (F7L and F11L) were tested in this method, alongside with paints containing high Tg binder (F7H and F11H) that were used as control paints. It was observed that F11L could resist more than twice wet scrub cycles compared to F7L (Table 5 and FIG. 8). In contrast, F11H does not show any considerable improvement in a similar testing compared to F7H. This result proves that ICES additive 1 is able to successfully enhance proper coalescing accompanied with Tg jump in F11L.

TABLE-US-00005 TABLE 5 Results of Wet Scrub Resistance (Cycles) Wet Scrub Resistance (Cycles) F7H F7L F11H F11L 81 94 90 193

3.2.1.2. Water Mark Test

[0156] As one important application of the present disclosure was on exterior coatings, it was also highly important to ensure that the formulated paint film would not leave any stains upon contact with water. Water mark tests were conducted on paint films containing formulations F7L and F11L (FIG. 9).

[0157] 1 ml of water was placed onto both samples (FIG. 9A and FIG. 9B) which were wiped off after 15 mins. No water marks were observed in both specimens (FIG. 9C and FIG. 9D). As such, it could be concluded that water soluble components of the formulation are not washed away nor had any wetting effect upon contact with water. This also helps to show that the physical interactions between the latex and inorganic particles were fully maximized as a result.

3.2.1.3. Print Resistance Test

[0158] The print resistance tests were performed following ASTM D2064-91(2016) which basically test the ability of a coating to resist accidental imprint on it due to applied pressure on the coated surface, especially at higher temperature. On the other hand, this test is also important to describe the ability of the paint to resist its surface smoothness particularly in contact with rough texture. Interestingly, it was observed that both low and high Tg formulations are free from such issues and does not show any impression of the standard cotton texture even at a temperature of 90° C. (FIG. 10).

3.2.2. Comparison with Commercial Paint (Permeability)

[0159] Permeability testing is useful in providing quantitative information on the performance of the paint coatings and its ability in allowing or preventing water vapour from passing through under different permeability cup conditions—namely wet cup i.e. high humidity (between 93% and 50%) and dry cup i.e. low humidity (50% and 3%). For this experiment, humidity was evaluated using different paint coatings. Saturated ammonium dihydrogen phosphate solution for the wet cup method and anhydrous calcium chloride was used for the dry cup method.

3.2.3. Method for Performing Permeability Test

[0160] FIG. 11 is a schematic flowchart 100 for illustrating the experiment set-up for permeability testing of the paint coatings designed in accordance with various embodiments disclosed herein. At steps 102 to 104, two layers of coating were applied onto a release paper (Form RP-1k) using a 120μ KBar applicator and left to dry in a freely circulating air at (23±2)° C. and (50±5)% relative humidity. At steps 106 to 108, after drying, paint film was carefully removed from the release paper and cut to shape, according to the individual cup dimensions—10 cm.sup.2 and 25 cm.sup.2 and its thickness measured. At steps 110, 112 to 114, the paint film was then secured onto the permeability cup with the following conditions; dry cup (anhydrous calcium chloride) or wet cup (saturated ammonium dihydrogen phosphate solution). At step 116, test assembly was placed in a test enclosure maintained at (23±2)° C. and (50±5)% relative humidity. At step 118, the cup was weighed at different intervals to determine the loss or gain in mass and returned to the test enclosure to continue testing after weighing. The test is considered complete when three or more points lie in a straight line. This method is accurate for water vapour transmission rates of 680 g/(m.sup.2.Math.d) and below.

3.3. Result

[0161] The following paint films were prepared for permeability testing:

[0162] 1. Nippon Weatherbond

[0163] 2. Nippon Roofguard

[0164] 3. Nippon Aqua Bodelac

[0165] 4. F11H Formulation

[0166] As wet cup permeability measures the loss of water vapour through the paint film, a general downward trend was observed. The inverse can be seen for dry cup permeability testing.

[0167] A best fit line was achieved based on the data collected from the experiment which passes through at least three points on the graph.

[0168] The water vapour transmission rate can be calculated as follows:

[00001]$\begin{array}{cc}V=24\times \left(\frac{p}{p_0}\right)\times \left(\frac{G}{A}\right)& \left(1\right)\end{array}$

[0169] G—Rate of flow of water vapour, in grams per hour, through the test piece (g/h)

[0170] A—Area of the test piece through which the water vapour flows (m.sup.2)

[0171] p—Atmospheric pressure at place of measurement (Pa)

[00002]$\begin{array}{cc}p=p_0-\left(\frac{h}{8.5}\right);\mathrm{where}{p}_0=101325\mathrm{Pa}& \left(2\right)\end{array}$

[0172] h=height of lab above sea level (15 m for Singapore) (m)

The results obtained are provided in Tables 6 to 8 and FIGS. 12 to 14 respectively.

TABLE-US-00006 TABLE 6 Wet Cup Permeability Calculations for Nippon Weatherbond and Nippon Roofguard Nippon Nippon Parameter Weatherbond Roofguard Surface Area (cm.sup.2) 10 (0.001) 25 (0.0025) Rate of Flow of Water 0.0235 0.0595 Vapour (G) (g/h) Water Vapour Transmission 564 571 Rate (V) (g/m.sup.2 .Math. day)

TABLE-US-00007 TABLE 7 Dry Cup Permeability Calculations for Nippon Aqua Bodelac and Nippon Weatherbond Nippon Nippon Parameter Aqua Bodelac Weatherbond Surface Area (cm.sup.2) 10 (0.001) 25 (0.0025) Rate of Flow of Water 0.0034 0.0048 Vapour (G) (g/h) Water Vapour Transmission 82 46 Rate (V) (g/m.sup.2 .Math. day)

TABLE-US-00008 TABLE 8 Dry and Wet Cup Permeability Calculations for F1 Formulation F11H F11H Parameter Dry Cup Wet Cup Surface Area (cm.sup.2) 10 (0.001) 25 (0.0025) Rate of Flow of Water 0.0011 0.1149 Vapour (G) (g/h) Water Vapour Transmission 26 1123 (>680) Rate (V) (g/m.sup.2 .Math. day)

3.3.1 Discussion

[0173] Based on the calculated values above, it was observed that the F11L formulation gave a much lower water vapour transmission rate under dry cup conditions as compared to both benchmark paints—Nippon Aqua Bodelac and Nippon Weatherbond. This shows that F11L formulation would perform better for applications where high relative humidity are not anticipated as compared to the two commercially available paints in the market.

3.4. Comparison with Commercial Paint (Weathering)

[0174] For the natural exposure/weathering tests, the inventors have designed an exposure rack that can be set at different angles such as 0°, 45° and 90°. The exposure rack complies with ISO 2810 [EN ISO Standard 2810, 2004, “Paints and varnishes. Natural weathering of coatings. Exposure and assessment,” European Committee for Standardization (CEN), ISBN 0 580 44141 5, http://www.bsigroup.com].

[0175] A picture of the exposure rack is shown in FIG. 15. The exposure rack can hold a metal and a concrete substrate. The plan for the test was that for each paint sample, 4 specimens are prepared. The specimen size is about 10 cm*12 cm (L*B) and one specimen was tested after every 3 months for a time span of 1 year. After the weathering tests, different defects such as chalking, cracking, blistering etc. were found. The tests for these defects and other properties were finalized, which are shown in Table 9 and have to be performed after the exposure. The tests are common for Accelerated Weathering as well and are in accordance with the ASTM D4857 [ASTM Standard D4587, 2011, “Standard Practice for Fluorescent UV-Condensation Exposures of Paint and Related Coatings,” American Society for Testing and Material (ASTM) International, DOI: 10.1520/D4587-11, www.astm.org.]. The test for defects performed for both weathering process depend on the type or application of the paint. The tests for defects such as rusting, chalking, checking etc. are all based on comparing the specimen with a visual standard that is provided by ASTM. Specular gloss was measured at Institute of Chemical and Engineering Sciences (ICES).

TABLE-US-00009 TABLE 9 Tests after Accelerated/Natural Weathering (ASTM D4857) Defects/ Roof Exterior Metal Wood ASTM Property Coating Paint Coating Gloss Standard Specular gloss ✓ ✓ ✓ ✓ D523 Rusting ✓ D610 Chalking ✓ D4214 Checking ✓ ✓ ✓ ✓ D660 Erosion ✓ D662 Blistering ✓ ✓ ✓ D714

[0176] FIG. 16 shows photographs obtained from the weathering tests performed on formulations designed in accordance with various embodiments disclosed herein. Photographs were taken in December 2017, January 2018 and March 2018.

Example 4: Latex, Silica Nanoparticles and Formulation

4.1. Latex Systems

[0177] FIG. 17 shows an experimental set up 200 for performing emulsion polymerisation 202 to form latex: starved feeding of monomer to avoid composition drift. FIG. 18 shows a schematic diagram 300 for illustrating emulsion polymerisation. The emulsion is made up of emulsifier micelles 302 and monomer droplets 304. At step 306, as polymerisation continues, emulsifier micelles 302 grow by monomer droplets 304 addition and are converted into latex particles 308.

TABLE-US-00010 TABLE 10 Summary of Synthesized Latex Systems Solid Tg Mw Latex content Initiator Temp Surfactant Stir size (° C.) GPC Name Composition % % ° C. % rpm nm DMA (THF) PDI EM3 Sty (26%), 30 1 70 4 300 42 37.1 105 kD 4.290 2EHA (38%), MMA (30%), MAA (6%) EM20 Sty (26%), 30 1 70 4 300 41 15.0 58 kD 2.262 2EHA (48%), MMA (20%), MAA (6%) EM30 Sty (27.5%), 50 1 70 1 300 216 2.1 377 kD 4.792 2EHA (49.5%), MMA (21.5%), MAA (1.5%)

[0178] Details of 3 other latex systems prepared in accordance with the procedure described above are provided in Table 10. Sodium dodecyl sulfate (SDS) is used as the surfactant and ammonium persulfate is used as the initiator.

4.2. Silica Nanoparticles

[0179] FIG. 19 shows a transmission electron microscopic (TEM) image of silica used in the method designed in accordance with various embodiments disclosed herein. As shown, the particle size of SiO.sub.2 falls within the range of between 10.28 nm and 14.48 nm. FIG. 20 is a graph showing the glass transition temperature (Tg) of exemplary latex designed in accordance with various embodiments disclosed herein and nanocomposites loaded with varying wt % of SiO.sub.2nanoparticles.

4.3. SOC and/or Plasticizer Free Paint Formulation

[0180] FIG. 21 shows a schematic diagram 400 for illustrating a method of preparing paint formulation in accordance with various embodiments disclosed herein. At step 402, a mill base containing components including water, CaCO.sub.3, TiO.sub.2, cloisite Na.sup.+ are combined with a latex binder in a let-down process to form paint formulation.

[0181] A blank and an ICES plasticizer free paint formulation designed in accordance with various embodiments disclosed herein (hereinafter referred to as “iPF Paint”) were prepared and details of the components present are provided in Table 11. Table 12 lists the glass transition temperature (Tg) of latex, blank and iPF Paint, as measured with dynamic mechanical analysis (DMA).

TABLE-US-00011 TABLE 11 Paint Formulation using Latex EM30 Components Blank (g) iPF Paint* (g) Mill base 1 Water 32.5 32.5 2 Defoamer (BYK014) 0.25 0.25 3 Ammonia 1 drop 1 drop 4 Dispersant (BYK154) 1 1 5 TiO.sub.2 (Tronox) 55 55 6 CaCO.sub.3 37.5 37.5 7 Thickener (clay) 0.375 0.375 8 Silica (additives) — 0.825 Let Down 9 Latex EM30 82.5 82.5 *iPF Paint = ICES Plasticizer free paint

TABLE-US-00012 TABLE 12 Tg of Latex Systems, Blank and iPF Paints Tg ° C. (From DMA) Latex Blank iPF Paint Latex EM30  2.1  8 20 Latex EM31 20.5 25 32 *iPF Paint = ICES Plasticizer free paint

[0182] Latex EM30=styrene (27.5%), 2-ethyl hexyl acrylate (49.5%), MMA (21.5%) and MAA (1.5%)

[0183] Latex EM31=EM31=(27.5%), 2-ethyl hexyl acrylate (44.5%), MMA (26.5%), MAA (1.5%).

[0184] Preliminary observations (FIG. 22): [0185] No cracks in the film [0186] No water marks [0187] No chalking

4.4. Performance Evaluation

4.4.1. Wet Scrub Resistance (Cycles)

[0188] Wet abrasion scrub resistance tests were performed on the blank and iPF Paint. Results are provided in FIG. 23 and Table 13.

TABLE-US-00013 TABLE 13 Results of Wet Scrub Resistance (Cycles) Wet Scrub Resistance (Cycles) Blank iPF Paint 90 193

4.4.2. Permeability (D1653)

[0189] Permeability tests were performed on iPF Paint and compared with commercial paints namely, Nippon Weatherbond and Nippon Aqua Bodelac. Results are provided in Table 14.

TABLE-US-00014 TABLE 14 Wet Cup and Dry Cup Permeability Calculations Rate of flow Permeance (WVP) Surface of water grams per m.sup.2 per 24 h Paint/ area, A vapour, G millimetre of mercury Thickness Parameter (m.sup.2) (g/h) (metric perms) (μm) Experimental results of wet cup permeability test Nippon 0.0025 0.0259  0.0050   35.9 Weatherbond (vapor impermeable) Nippon 0.001  0.004   0.0019   123.4 Aqua (vapor impermeable) Bodelac iPF Paint 0.0025 0.0699  0.0358   14.7 (vapor impermeable) Experimental results of dry cup permeability test Nippon 0.0025 0.0042  0.0020   144 Weatherbond (vapor impermeable) Nippon 0.001  0.0029  0.0034   144 Aqua (vapor impermeable) Bodelac iPF Paint 0.0025 0.00057 0.000218 13.1 (vapor impermeable) Four Classifications of Vapor Permeance* Classification Permeance Vapor impermeable 0.1 perm or less Vapor semi- 1.0 perm or less and impermeable greater than 0.1 perm Vapor semi- 10 perms or less and permeable greater than 1.0 perm Vapor permeable Greater than 10 perms *Source: Lstiburek, Joseph. 850-106: Understanding Vapor Barriers. Building Science Corporation. Apr. 15, 2011.

4.4.3. Q-Lab's Accelerated Weathering Tester (QUV) Exposure Test—ASTM D4587

[0190] QUV exposure testing involves a 1.sup.st step under UV light and a 2.sup.nd step in the dark. The conditions used in each step are detailed in Table 15.

TABLE-US-00015 TABLE 15 Steps and Conditions in QUV Exposure Testing 1.sup.st step: UV 2.sup.nd step: Dark To simulate sunlight- To simulate using UVA lamps condensation Duration: 4 h Duration: 4 h Irradiance: 0.89 W/m2 Irradiance: NA Temp: 60° C. Temp: 50° C.

[0191] FIG. 24 shows photographs of Nippon Aqua Bodelac and Dulux Gloss paint films after 72 hours of exposure. As shown, there was no physical changes after 72 hours. FIG. 25 shows photographs of paint films before and after 72 hours of QUV exposure test. FIG. 25A shows blank. FIG. 25B shows iPF Paint and FIG. 25C shows iPF Colour Paint.

4.4.5. Natural Exposure/Weathering Test

[0192] The formulations were tested in Nanyang Technological University (NTU) under natural outdoor weathering for 3 months.

[0193] FIG. 26 shows photographs of Nippon Aqua Bodelac and Dulux Gloss paint films after 3 months of natural exposure/weathering. FIG. 27 shows photographs of paint films on concrete and metal substrates after 3 months of natural exposure/weathering. FIG. 27A shows blank. FIG. 27B shows iPF Paint. As shown, the blank paint failed but iPF Paint was still as it was after 3 months of outdoor weathering test.

[0194] FIG. 28 shows photographs obtained from the weathering tests performed on commercial formulations and formulations designed in accordance with various embodiments disclosed herein. FIG. 28A shows Dulux Gloss. FIG. 28B shows Aqua Bodelac. FIG. 28C and FIG. 28D shows F1 with and without primer respectively. FIG. 28E shows F2 with primer.

CONCLUSION

[0195] The inventors have surprisingly found out that the concept of nanoconfinement effect may be applied to create water-based formulation that may be scaled up for industrial applications. Advantageously, by relying on this concept of a nanoconfinement effect to cause a Tg jump, aqueous polymer (e.g. latex) may be tuned with inorganic particles in the final complex formulation to achieve good film forming property and eventually allows a good quality film to be formed.

[0196] It should be appreciated that the concept of using Tg jump caused by interactions between the waterborne polymers (e.g. latex) with designed chain structures and the nanoadditives, to bring about plasticizer-free formulations is a unique, one of its kind approach.

[0197] Such an approach in making plasticizer-free formulations is indeed surprising and cannot be easily expected. This is because, in the current paint industry, VOCs or SOCs (i.e. the harmful additives) are deliberately used (usually under the names of film forming agent, plasticizer, coalescing agent etc) as the general conventional wisdom is that they are essential and indispensable.

[0198] For example, in known coating formulations such as acrylate based latex paints, SOCs or VOCs are essential components of the formulations. This is because in currently known methods, proper film formation still requires the aid of such small molecules that can intercalate between the polymer chain in order to lower the latex glass transition temperature (Tg). The reduced Tg will then aid the film formation. Upon VOC/SOC/solvent evaporation, there will be a jump on the Tg and the polymer film reverts to its original glass transition temperature in order to produce protective films that are non-tacky with other desirable properties such as mechanical strength. This conventional technology is almost like a modified form of solvent based paint where the plasticizer is working as solvent. Therefore, the use of SOCs or volatile organic compounds (VOCs) in the form of plasticizers remains necessary in current methods used to prepare coating formulations.

[0199] Attempting to study the interactions between nano additives in polymer-nanoparticle composites prepared by conventional solvent based approaches with an aim of extrapolating any findings to a water based system is also extremely challenging and far from being straightforward.

[0200] In such conventional solvent based approaches, an increase or decrease in Tg depends on the nature of interaction between the inorganic particle and polymer chains; and such interactions in a solvent based approach cannot be easily extrapolated to a water based system, especially given that excessive interaction may take place between nanoparticle and groups in the polymer (e.g. latex) with water molecules through hydrogen bonding.

[0201] Indeed, due to the complexity of interactions that take place between nanoparticle and groups in the polymer (e.g. latex) with water molecules in a water-based system, such a system has never been studied in water-based composites. In addition, a water-based paint system of interest adds another level of complexity when a latex particle instead of a soluble particle is used. In this regard, prior to the inventors' findings, it is entirely unclear if the latex particle will undergo inter-diffusion to form a non-tacky film in the presence of interacting polymer and inorganic nanoparticle.

[0202] Furthermore, as the paint system usually contains a very large amount of inorganic solids (pigments and fillers), it is doubtful whether a nanoconfinement effect will be effective under such conditions, especially when Tg measurement is not practical in many cases.

[0203] Thus, successfully replicating this Tg jump effect by relying on nanoconfinement as a mode of plasticization of the polymer (e.g. latex) without the addition of VOC to create a paint film is a feat that is by no means trivial. Such a finding is even more surprising against the current backdrop of paint industries being inextricably reliant on VOCs for their paint formulations to date.

[0204] In summary, it should be appreciated that the presently disclosed concept of using inorganic particles in the composition as a plasticizer replacement is unique and unexpected in several ways and these include but are not limited to: [0205] the use of non-covalent interaction to induce Tg jump to remove plasticizer. [0206] the use of a particular and very small amount (e.g. 1-2 wt %) of inorganic nanoparticle (e.g. silica SiO.sub.2) as a substitute for conventionally used plasticizer in water based polymer (e.g. latex) paint formulation. (It is noted that inorganic nanoparticle is not working as plasticizer, and embodiments of the composition disclosed herein do not require any plasticizer and are thus unique). [0207] the unexpected result of non-covalent interaction of polymer (e.g. latex) with a particular inorganic nanoparticle (e.g. silica SiO.sub.2) that is present as a part of a complex mixture of different nanoparticles having different sizes, functionalities, and densities; and polymer binders having different molecular weights and end chain functionalities. [0208] the unexpected result that just a small amount (e.g. 1-2 wt %) of inorganic nanoparticle (e.g. SiO.sub.2) can function predominantly in a mixture of large amounts (e.g. 40-50 wt %) of other inorganic fillers/pigments in a paint to still achieve the desired effect. [0209] the surprising finding that the non-covalent interaction between inorganic nanoparticle and polymer binder can be directly measured for an unknown material and can be directly correlated with Tg.

[0210] In conclusion, the examples show that nanoconfinement effect can be used to create volatile organic compounds (VOC) free coating and/or small organic compound (SOC) free coating in various embodiments of the present disclosure. Accordingly, the examples also show that embodiments of composition/paint composition/coating formulation/film/kit/coated substrate can be substantially devoid of a plant dispersant which may act as a plasticizer. Similarly, embodiments of the composition/paint composition/coating formulation/film/kit/coated substrate disclosed herein can also be substantially devoid of high boiling small molecules that may be creating plasticizing effect (e.g. low volatile plasticizer).

[0211] Therefore, embodiments of the composition/paint composition/coating formulation/film/kit/coated substrate disclosed herein advantageously do not pose as an environmental hazard or pollute the environment. Advantageously, in various embodiments, the composition/paint composition/coating formulation/film/kit/coated substrate is environmentally benign/friendly as the composition is a water-based product design which do not contain harmful organic solvents or plasticizers.

[0212] Embodiments of the presently disclosed method also provide a commercially viable strategy to produce small organic compounds (SOC) and/or plasticizer free formulations as use of complicated processes was avoided and no significant changes to current running production plants may be required.

[0213] Embodiments of the formulations disclosed herein may also be produced at a lower price while showing advantageous properties in terms of various paint characteristics which include good results in scrub resistance stability and accelerated weathering experiments when compared to commercial formulations which contain VOC.

[0214] 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.