SULFONATE-FUNCTIONAL COATING COMPOSITIONS, METHODS OF MAKING THE SAME, AND ARTICLES THEREFROM
20210198494 · 2021-07-01
Inventors
Cpc classification
C09D4/00
CHEMISTRY; METALLURGY
International classification
Abstract
Described herein is a coating composition comprising: (a) a zwitterionic compound comprising (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (b) an acid-catalyzed hydrolysis product of an alkoxylsilane, wherein the acid-catalyzed hydrolysis product of an alkoxylsilane comprises at least one (i) (RO)(.sub.4-a)Si(OH).sub.a where R is a monovalent hydrocarbon group and a is an integer from 1 to 4; or (ii) an alkanol silicate acid oligomer; (c) a water-miscible organic solvent; and (d) water, along with articles thereof and methods of making the same.
Claims
1. A coating composition comprising (a) a zwitterionic compound comprising (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (b) an acid-catalyzed hydrolysis product of an alkoxylsilane, wherein the acid-catalyzed hydrolysis product of an alkoxylsilane comprises at least one (i) (RO).sub.(4-a)Si(OH).sub.a where R is a monovalent hydrocarbon group and a is an integer from 1 to 4; or (ii) an alkanol silicate acid oligomer; (c) a water-miscible organic solvent; and (d) water.
2. The coating composition of claim 1, wherein the zwitterionic compound is of Formula (I)
(R.sup.1O).sub.p—Si(Q.sup.1).sub.q—X—N.sup.+(Y.sup.1Y.sup.2)—(Z)—SO.sub.3.sup.− (I) Wherein each R.sup.1 is independently a hydrogen, methyl group, or ethyl group; each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms; p is 1, 2, or 3; q is 0, 1, or 2; p+=3; X is a divalent alkylene group comprising at least 2, and no more than 12 carbon atoms and optionally comprising at least one ether linkage, at least one carbamate linkage, and/or at least one urea linkage; Y.sup.1 and Y.sup.2 are each independently a monovalent alkyl group; and Z is a divalent alkylene group comprising at least 2 and no more than 12 carbon atoms and optionally comprising a pendent hydroxyl group.
3. The coating composition of claim 1, wherein the zwitterionic compound is of Formula (III)
(R.sup.1O).sub.p—Si(Q.sup.1).sub.q—CH.sub.2CH.sub.2CH.sub.2—N.sup.+(CH.sub.3).sub.2—(CH.sub.2).sub.m—SO.sub.3.sup.− (III) wherein: each R.sup.1 is independently a hydrogen, methyl group, or ethyl group; each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms; p and m are integers of 1 to 4; q is 0 or 1; and p+q=3.
4. The coating composition of claim 1, wherein the zwitterionic compound is of Formula (II)
(R.sup.1O).sub.p—Si(Q.sup.1).sub.q—(X).sub.r—(pyradinyl)-(Z)—SO.sub.3.sup.− (II) Wherein each R.sup.1 is independently a hydrogen, methyl group, or ethyl group; each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms; p is 1, 2, or 3; q is 0, 1, or 2; p+q=3; r is 0 or 1; X is a divalent alkylene group comprising at least 2, and no more than 12 carbon atoms and optionally comprising at least one ether linkage, at least one carbamate linkage, and/or at least one urea linkage; pyridinyl is a divalent pyridine group; and Z is a divalent alkylene group comprising at least 2 and no more than 12 carbon atoms and optionally comprising a pendent hydroxyl group.
5. The coating composition of claim 1, wherein the zwitterionic compound is selected from at least one of: ##STR00004##
6. The coating composition of claim 1, wherein the acid-catalyzed hydrolysis product of an alkoxysilane comprises (RO).sub.(4-a)Si(OH).sub.a and R is a monovalent hydrocarbon group comprising 1 or 2 carbon atoms and a is an integer from 1 to 4.
7. The coating composition of claim lany one of the previous claims, wherein the alkanol silicate acid oligomer comprises a C1 to C2 alkanol.
8. The coating composition of claim 1, wherein the alkanol silicate acid oligomer has a molecular weight of less than 1,000 daltons.
9. The coating composition of claim 1, wherein the water-miscible organic solvent is selected from at least one of methanol, ethanol, isopropanol, and 1-methoxy-2-propanol.
10. The coating composition of claim 1, wherein the coating composition comprises less than 2.5 wt % of an alkali or alkaline earth metal.
11. The coating composition of claim 1, wherein the coating composition is substantially free of inorganic particles.
12. The coating composition of claim 1, wherein the coating composition comprises a surfactant, optionally wherein the surfactant is selected from an alkyl sulfate, alkyl ether sulfate, alkyl ethoxylate, and combinations thereof.
13. An article comprising a substrate with a coating layer thereon, wherein the coating layer is preparable by combining the components comprising: (a) a zwitterionic compound comprising (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (b) an acid-catalyzed hydrolysis product of an alkoxylsilane, wherein the acid-catalyzed hydrolysis product of an alkoxylsilane comprises at least one (i) (RO).sub.(4-a)Si(OH).sub.a where R is a monovalent hydrocarbon group and a is an integer from 1 to 4; or (ii) an alkanol silicate acid oligomer; (c) a water-miscible organic solvent; and (d) water.
14. The article of claim 13, wherein the coating layer has a thickness of at least 100 nm.
15. The article of any one of claim 13, wherein the receding contact angle of the preparable coating layer on the substrate is less than 30 degrees.
16. The article of any one of claim 13, wherein the substrate is at least one of a corona-treated polyethylene terepthalate and nano-silica coated polyethylene terepthalate.
17. A method comprising: contacting (a) an acid-catalyzed hydrolysis product of an alkoxysilane with (b) a zwitterionic compound, wherein the zwitterionic compound comprises (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (c) a water-miscible organic solvent; and (d) water to form a coating composition.
18. The method of claim 17, wherein the acid--catalyzed hydrolysis product of an alkoxysilane is derived from an alkoxysilane and a weak acid, optionally, wherein the alkoxysilane is a tetraalkoxysilane comprising 1-4 carbon atoms per alkoxy group, and optionally, wherein the weak acid has a boiling point of less than 200° C. at ambient pressure.
19. The method of claim 18, wherein the weak acid is at least one of a carboxylic acid and a phosphonic acid.
20. The coating composition of claim 1, wherein the coating composition comprises at least 0.1 wt % of the zwitterionic compound.
Description
[0071] Exemplary embodiments of the present disclosure, include, but are not limited to the following:
[0072] Embodiment 1. A coating composition comprising (a) a zwitterionic compound comprising (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (b) an acid-catalyzed hydrolysis product of an alkoxylsilane, wherein the acid-catalyzed hydrolysis product of an alkoxylsilane comprises at least one (i) (RO).sub.(4-a)Si(OH).sub.a where R is a monovalent hydrocarbon group and a is an integer from 1 to 4; or (ii) an alkanol silicate acid oligomer;
[0073] (c) a water-miscible organic solvent; and (d) water.
[0074] Embodiment 2. The coating composition of embodiment 1, wherein the zwitterionic compound is of Formula (I)
(R.sup.1O).sub.p-Si(Q.sup.1).sub.q—X—N.sup.+(Y.sup.1Y.sup.2)—(Z)—SO.sub.3 (I)
[0075] wherein each R.sup.1 is independently a hydrogen, methyl group, or ethyl group;
[0076] each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms;
[0077] p is 1, 2, or 3;
[0078] q is 0, 1, or 2;
[0079] p+q=3;
[0080] X is a divalent alkylene group comprising at least 2, and no more than 12 carbon atoms and optionally comprising at least one ether linkage, at least one carbamate linkage, and/or at least one urea linkage; Y.sup.1 and Y.sup.2 are each independently a monovalent alkyl group; and Z is a divalent alkylene group comprising at least 2 and no more than 12 carbon atoms and optionally comprising a pendent hydroxyl group.
[0081] Embodiment 3. The coating composition of any one of the previous embodiments, wherein the zwitterionic compound is of Formula (III)
(R.sup.1O).sub.p—Si(Q.sup.1).sub.q—CH.sub.2CH.sub.2CH.sub.2—N.sup.+(CH.sub.3).sub.2—(CH.sub.2).sub.m—SO.sub.3— (III)
wherein:
each R.sup.1 is independently a hydrogen, methyl group, or ethyl group; each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms; p and m are integers of 1 to 4; q is 0 or 1; and p+q=3.
[0082] Embodiment 4. The coating composition of embodiment 1, wherein the zwitterionic compound is of Formula (II)
(R.sup.1O).sub.p—Si(Q.sup.1).sub.q—(X).sub.r—(pyradinyl)—(Z)—SO.sub.3— (II)
Wherein each R.sup.1 is independently a hydrogen, methyl group, or ethyl group; each Q.sup.1 is independently selected from hydroxyl, alkyl groups containing from 1 to 4 carbon atoms and alkoxy groups containing from 1 to 4 carbon atoms; p is 1, 2, or 3; q is 0, 1, or 2; p +q =3; r is 0 or 1; X is a divalent alkylene group comprising at least 2, and no more than 12 carbon atoms and optionally comprising at least one ether linkage, at least one carbamate linkage, and/or at least one urea linkage; pyridinyl is a divalent pyridine group; and Z is a divalent alkylene group comprising at least 2 and no more than 12 carbon atoms and optionally comprising a pendent hydroxyl group.
[0083] Embodiment 5. The coating composition of any one of the previous embodiments, wherein the zwitterionic compound is selected from at least one of:
##STR00002##
[0084] Embodiment 6. The coating composition of any one of the previous embodiments, wherein the acid-catalyzed hydrolysis product of an alkoxysilane comprises (RO).sub.(4-a)Si(OH).sub.a and R is a monovalent hydrocarbon group comprising 1 or 2 carbon atoms and a is an integer from 1 to 4.
[0085] Embodiment 7. The coating composition of any one of the previous embodiments, wherein the alkanol silicate acid oligomer comprises a C1 to C2 alkanol.
[0086] Embodiment 8. The coating composition of any one of the previous embodiments, wherein the alkanol silicate acid oligomer has a molecular weight of less than 1,000 daltons.
[0087] Embodiment 9. The coating composition of any one of the previous embodiments, wherein the water-miscible organic solvent is selected from at least one of methanol, ethanol, isopropanol, and 1-methoxy-2-propanol.
[0088] Embodiment 10. The coating composition of any one of the previous embodiments, wherein the coating composition comprises at least 0.1 wt % of the zwitterionic compound.
[0089] Embodiment 11. The coating composition of any one of the previous embodiments, wherein the coating composition comprises at least 0.1 wt % of the acid-catalyzed hydrolysis product of the alkoxysilane.
[0090] Embodiment 12. The coating composition of any one of the previous embodiments, wherein the coating composition comprises at least 75 wt % of the water.
[0091] Embodiment 13. The coating composition of any one of the previous embodiments, wherein the coating composition comprises at least 0.1% solids.
[0092] Embodiment 14. The coating composition of any one of the previous embodiments, wherein the coating composition comprises less than 2.5 wt % of an alkali or alkaline earth metal.
[0093] Embodiment 15. The coating composition of any one of the previous embodiments, wherein the coating composition is substantially free of inorganic particles.
[0094] Embodiment 16. The coating composition of any one of the previous embodiments, wherein the coating composition comprises a surfactant.
[0095] Embodiment 17. The coating composition of embodiment 16, wherein the surfactant is selected from an alkyl sulfate, alkyl ether sulfate, alkyl ethoxylate, and combinations thereof
[0096] Embodiment 18. An article comprising a substrate with a coating layer thereon, wherein the coating layer is preparable by combining the components comprising: (a) a zwitterionic compound comprising (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (b) an acid-catalyzed hydrolysis product of an alkoxylsilane, wherein the acid-catalyzed hydrolysis product of an alkoxylsilane comprises at least one (i) (RO).sub.(4-a)Si(OH).sub.a where R is a monovalent hydrocarbon group and a is an integer from 1 to 4; or (ii) an alkanol silicate acid oligomer; (c) a water-miscible organic solvent; and (d) water.
[0097] Embodiment 19. The article of embodiment 18, wherein the coating layer has a thickness of at least 100 nm.
[0098] Embodiment 20. The article of any one of embodiments 18-19, wherein the receding contact angle of the preparable coating layer on the substrate is less than 30 degrees.
[0099] Embodiment 21. The article of any one of embodiments 18-20, wherein the substrate is at least one of a corona-treated polyethylene terepthalate and nano-silica coated polyethylene terepthalate.
[0100] Embodiment 22. The article of any one of embodiments 18-21, wherein the article is a sensor.
[0101] Embodiment 23. A method comprising:
[0102] contacting (a) an acid-catalyzed hydrolysis product of an alkoxysilane with (b) a zwitterionic compound, wherein the zwitterionic compound comprises (i) sulfonate-functional groups and (ii) alkoxysilane groups and/or silanol-functional groups; (c) a water-miscible organic solvent; and (d) water to form a coating composition.
[0103] Embodiment 24. The method of embodiment 23, wherein the acid-catalyzed hydrolysis product of an alkoxysilane is derived from an alkoxysilane and a weak acid.
[0104] Embodiment 25. The method of embodiment 24, wherein the alkoxysilane is a tetraalkoxysilane comprising 1-4 carbon atoms per alkoxy group.
[0105] Embodiment 26. The method of any one of embodiments 24-25, wherein the weak acid has a boiling point of less than 200° C. at ambient pressure.
[0106] Embodiment 27. The method of any one of embodiments 24-26, wherein the weak acid is at least one of a carboxylic acid and a phosphonic acid.
[0107] Embodiment 28. The method of any one of embodiments 23-27, further comprising contacting the coating composition to a substrate surface.
[0108] Embodiment 29. The method of embodiment 28, wherein the receding contact angle of the coating composition disclosed herein on an embodied substrate is less than 30 degrees.
[0109] Embodiment 30. The method of any one of embodiments 28-29 wherein the substrate is a polyethylene terephthalate.
[0110] Embodiment 31. The method of embodiment 30, wherein the surface of the polyethylene terephthalate is corona-treated, comprises a silica layer, or comprises a primer.
[0111] Embodiment 32. The method of any one of embodiments 28-31, further comprising at least partial removal of the water-miscible organic solvent and water to form a layer.
[0112] Embodiment 33. The method of embodiment 32, wherein the layer has a thickness of at least 100 nm.
EXAMPLES
[0113] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight (wt), and all reagents used in the examples were obtained, or are available, from general chemical suppliers such as, for example, Sigma-Aldrich Company, Saint Louis, Mo., or may be synthesized by conventional methods.
[0114] These abbreviations are used in the following examples: cm=centimeter, g=grams, ° C.=degrees Celsius, mL=milliliter, and nm=nanometer.
TABLE-US-00001 Material designation Description TEOS Tetraethoxysilane was obtained from Alfa Aesar (Tewksbury, MA). Surfactant Sodium lauryl ether sulfate, sold under trade designation “POLYSTEP B-430S,” available from Stepan, Inc. (Northfield, IL). Zwitterionic silane
[0115] Test Methods
[0116] %Haze:
[0117] Haze measurements were made using a BYK Haze-Gard Plus, Model No. 4725 (BYK-Gardner USA, Columbia, Md.), an integrating sphere instrument having 0°/diffuse geometry and CIE standard illuminant C. Samples were placed directly at the haze port for measurement of haze. Reported values are an average of three measurements. Error values are reported as one standard deviation.
[0118] Wet Abrasion Resistance:
[0119] Coated samples were first soaked in deionized water overnight and allowed to air dry for at least 1 hour prior to testing to eliminate residual coating surfactant that might affect the test.
[0120] In a 1000 mL covered beaker, 400 mL of water was heated to 60° C. The lid contained a circular cut opening of 4 cm diameter, which was covered with a metal plate. The plate was removed, and the coated sample was immediately placed over the opening with the coated side facing the inside of the beaker and left there for 60 seconds. Immediately after removing from the water vapor, the sample was rubbed 5 times with a low lint wiper available under trade designation “KIMTECH” (Kimberly-Clark, Roswell, Ga.) using moderate pressure. Damage to the coating was graded visually as follows: P=pass (the coating is unaffected), VSF=very slight fail (a few light scratches are visible), SF=slight fail (significant scratching is visible), F=fail (the coating is heavily scratched or mostly removed), or BF=big fail (the coating is completely wiped away).
[0121] Preparative Example 1 (PE-1): Acid-catalyzed hydrolysis product of TEOS
[0122] A jar was charged with 0.50 g of acetic acid, 24.0 g of ethanol, 15.5 g of water, and 10.0 g of TEOS. This solution was stirred for 4 hours. An additional 50.0 g of water was added, and the resulting solution was stirred overnight. The resulting hydrolyzed TEOS solution was used for coatings within 24 hours.
[0123] Comparative Examples 1-5 (CE 1-5)
[0124] Stock solutions were prepared by diluting lithium silicate and zwitterionic silane to 10 wt % solids in water. Surfactant was diluted to 1 w t% solids by weight. The coating solutions were then prepared by mixing stock solutions in the amounts shown in table 2 to form a clear and colorless solution. Each solution contained about 4 wt % solids.
TABLE-US-00002 TABLE 2 Ratio of 10% 1% zwitterion:lithium 10% lithium Sur- Example silicate zwitterion silicate factant water CE-1 2:1 800 mg 400 mg 30 mg 1.77 g CE-2 3:2 720 mg 480 mg 30 mg 1.77 g CE-3 1:1 600 mg 600 mg 30 mg 1.77 g CE-4 2:3 480 mg 720 mg 30 mg 1.77 g CE-5 1:2 400 mg 800 mg 30 mg 1.77 g
[0125] The solutions were coated on nanosilica-primed PET using a #12 wire-wound rod (BYK, inc., Wallingford, Conn.). The coatings were dried by blowing air over the films with a heat gun. The dried coatings were then cured in an oven held at 130° C. for 10 minutes.
[0126] Examples 1-5 (EX 1-5)
[0127] Stock solutions containing 10 wt % zwitterionic silane, 20 wt % zwitterionic silane, and 1 wt % Surfactant were prepared by diluting concentrated solutions with appropriate amounts of deionized water. The hydrolyzed TEOS solution described in PE-1 contained an estimated 2.88% solids. This assumes that upon curing TEOS condenses to SiO.sub.2. The stock solutions were mixed in the amounts shown in Table 3 to make clear and colorless coating solutions containing 4% solids.
TABLE-US-00003 TABLE 3 Ratio of 2.88% zwitterion:hydrolyzed 10% 20% hydrolyzed 1% Example TEOS zwitterion zwitterion TEOS Surfactant water EX-1 2:1 533 mg 0 925 mg 20 mg 522 mg EX-2 3:2 480 mg 0 1.11 g 20 mg 390 mg EX-3 1:1 400 mg 0 1.39 g 20 mg 190 mg EX-4 2:3 320 mg 0 1.66 g 20 mg 0 EX-5 1:2 0 133 mg 1.85 g 20 mg 0
[0128] The solutions were coated on nanosilica-primed PET using a #12 wire-wound rod available from BYK, Inc. (Wesel, Germany). The coatings were dried by blowing air over the films with a heat gun. The dried coatings were then cured in an oven held at 130° C. for 10 minutes.
[0129] Samples of coated films EX 1-5 and CE 1-5 were soaked in deionized water overnight, then allowed to air dry for one hour. The %haze was measured before and after soaking for each film following the % Haze test method and the percent change is haze is reported in Table 4. Samples of coated films EX 1-5 and CE 1-5 were also tested following the Wet Abrasion Resistance test method. The results are shown in Table 4.
TABLE-US-00004 TABLE 4 Change in Haze after Haze after Wet Initial haze soaking soaking abrasion Sample (%) (%) (%) test result CE-1 2.54 ± 0.09 5.71 ± 0.24 3.17 Big Fail CE-2 3.01 ± 0.49 9.32 ± 3.54 6.31 Big Fail CE-3 4.55 ± 0.76 10.30 ± 4.58 5.75 Big Fail CE-4 8.26 ± 1.17 24.0 ± 0.15 15.74 Fail CE-5 9.85 ± 1.17 20.8 ± 3.30 10.95 Big Fail EX-1 1.49 ± 0.05 1.98 ± 0.22 0.49 Very Slight Fail EX-2 2.27 ± 0.23 2.96 ± 0.41 0.69 Slight Fail EX-3 1.94 ± 0.04 2.75 ± 0.25 0.81 Pass EX-4 1.99 ± 0.04 2.25 ± 0.19 0.26 Very Slight Fail EX-5 10.60 ± 0.49 10.90 ± 1.95 0.30 Slight Fail
[0130] As shown in Table 4, the comparative examples had diminished water resistance, as shown by the increase in haze following soaking. The comparative examples also tended to have poorer performance in the wet abrasion test.
[0131] Comparative Example 6 (CE-6)
[0132] To show the importance of hydrolyzing the alkoxysilane before contact with the zwitterionic compound, a coating composition using the same mass amounts of components as in EX-3 was prepared except that the alkoxysilane was not hydrolyzed prior to contact with the zwitterionic compound. The coating composition was made as follows: A vial was charged with 4.00 g of 10 wt % zwitterionic silane in water, 11.0 g of water, 200 mg of 1 wt % Surfactant in water, 70 mg of acetic acid, 3.34 g of ethanol, and 1.39 g of TEOS. The resulting dispersion was stirred overnight. After stirring overnight, a precipitate formed, and the solution could not be used for coating.
[0133] Comparative Examples 7-9 (CE 7-9)
[0134] Coating solutions were prepared by mixing the stock solutions in the amounts shown in the Table 5 to generate coating layers having various thickness. The solutions were coated on corona-treated PET using wire-wound rods available from BYK, Inc. (Wesel, Germany). The rods used were #28, #16, and #6 for CE-7, CE-8, and CE-9, respectively. The coatings were dried by blowing air over the films with a heat gun. The dried coatings were then cured in an oven held at 130° C. for 10 minutes. The target dried coating thicknesses were 2.5 microns, 900 nm, and 100 nm for CE-7, CE-8, and CE-9, respectively.
TABLE-US-00005 TABLE 5 Wt % solids of a 1:1 ratio of 10 wt % 1 wt % zwitterion:lithium 10 wt % lithium Sur- Example silicate zwitterion silicate factant water CE-7 5% solids 500 mg 500 mg 20 mg 980 mg CE-8 3.6% solids 360 mg 360 mg 20 mg 1.26 g CE-9 1% solids 100 mg 100 mg 20 mg 1.78 g
[0135] Examples 6-8 (EX 6-8)
[0136] Coating solutions were prepared by mixing the stock solutions in the amounts shown in table 6. The solutions were coated on corona-treated PET using wire-wound rods available from BYK, Inc. (Wesel, Germany). The rods used were #28, #16, and #6 for EX-6, EX-7, and EX-8, respectively. The coatings were dried by blowing air over the films with a heat gun. The dried coatings were then cured in an oven held at 130° C. for 10 minutes. The target coating thicknesses were 2.5 microns, 900 nm, and 100 nm for EX-6, EX-7, and EX-8, respectively.
TABLE-US-00006 TABLE 6 Wt % solids of a 1:1 ratio of 2.88% zwitterion:hydrolyzed 10% 20% hydrolyzed 1% Example TEOS zwitterion zwitterion TEOS Surfactant water EX-6 5% solids 0 245 mg 1.70 g 20 mg 0 EX-7 3.6% solids 577 mg 0 1.00 g 20 mg 0 EX-8 1% solids 577 mg 0 1.00 g 80 mg 4.12 g
[0137] Samples of coated films EX 6-8 and CE 7-9 were visually inspected for appearance and then tested following the Wet Abrasion Resistance test method. The results are shown in Table 7.
TABLE-US-00007 TABLE 7 Visual coating appearance Wet abrasion Sample before testing test result CE-7 Heavy cracking of the coating and Big Fail heavy film curling CE-8 Cracking of the coating and film Big Fail curling CE-9 No cracking or curling Big Fail EX-6 No cracking or curling Pass EX-7 No cracking or curling Very slight fail EX-8 No cracking or curling Pass
[0138] As shown in table 7, the comparative examples demonstrated cracking at thicker coating layers (900 nm and 2.5 micron) and all of the comparative examples tended to have poorer performance in the wet abrasion test.
[0139] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned or incorporated by reference herein, this specification as written will prevail.