Anti-Fingerprint Coating Composition, Products Therefrom, Method for Forming the Same, And Use Thereof

Abstract

The present invention is directed to anti-fingerprint coating compositions, the coating layers and coated articles formed therefrom, the preparation methods therefor, and the uses thereof. The coating compositions and methods according to the present invention are capable of forming a coating layer with anti-fingerprint performance. The coating layer according to the present invention comprises a stationary phase impregnated with a mobile phase that can diffuse and fade fingerprints, in addition to optionally having a strong liquid repellency that minimizes the deposition of fingerprints and eases the cleaning of the coated articles.

Claims

1. A composition for forming a coating on top of a substrate, wherein the composition comprises: 100 parts by weight of a binder; and 10 to 50 parts by weight of a liquid comprising one or more surfactants with an HLB value greater than 6.f

2. The composition according to claim 1, wherein said liquid is a hydrophilic liquid comprising one or more surfactants with an HLB value of 10 or greater.

3. The composition according to claim 2, wherein the composition further comprises 10 to 40 parts by weight of one or more surfactants with an HLB value of greater than 6 to 10.

4. The composition according to claim 1, wherein the composition further comprises a low surface energy fluorine-containing additive.

5. The composition according to any claim 1, wherein the composition further comprises a dispersion of inorganic particles with a size ranging from 1 nm to 100 m, and wherein the inorganic particles are silica particles, alumina particles, zirconia particles, titania particles, vanadia particles, chromia particles, ceria particles, tin oxide particles, or a mixture thereof.

6. The composition according to claim 1, wherein said binder is a monomer, oligomer or polymer selected from the group of resins comprising acrylates, acrylics, alkyds, amines, amides, aminos, isocyanates, polyurethanes, epoxies, acrylic/epoxy hybrids, epoxy esters, polyesters, polyethers, polyvinyl alcohols, phenolics, polyvinyl acetates, styrenes, styrene-butadiene copolymers, silicone, polyvinyl butyrals, hydrocarbon resins, and mixtures thereof.

7. The composition according to claim 1, wherein said liquid is selected from alcohol ethoxylates, alcohol alkoxylates, phenol ethoxylates, nonyl phenol ethoxylates, amine ethoxylates, amide ethoxylates, alkylpolyglucosides, polyalcohols, polyoxylated alcohols, fatty acid esters, amine and amide derivatives, ethylene oxide/propylene oxide copolymers, silicone surfactants, and mixtures thereof.

8. A coating layer, which comprises: a stationary phase formed with a binder; a mobile phase prepared from a liquid comprising one or more surfactants with an HLB value greater than 6; wherein the mobile phase is impregnated within the stationary phase.

9. The coating layer according to claim 8, wherein said mobile phase is a hydrophilic liquid comprising one or more surfactants with an HLB value of 10 or greater.

10. The coating layer according to claim 9, wherein said mobile phase further comprises one or more surfactants with an HLB value of greater than 6 to 10.

11. The coating layer according to claim 8, wherein said stationary phase further comprises a low surface energy compound selected from fluorine-containing additives.

12. The coating layer according to claim 8, wherein said stationary phase further comprises inorganic particles with a size ranging from 1 nm to 100 m, and wherein the inorganic particles are silica particles, alumina particles, zirconia particles, titania particles, vanadia particles, chromia particles, ceria particles, tin oxide particles, or a mixture thereof.

13. The coating layer according to claim 8, wherein said binder is a monomer, oligomer or polymer selected from the group of resins comprising acrylates, acrylics, alkyds, amines, amides, aminos, isocyanates, polyurethanes, epoxies, acrylic/epoxy hybrids, epoxy esters, polyesters, polyethers, polyvinyl alcohols, phenolics, polyvinyl acetates, styrenes, styrene-butadiene copolymers, silicone, polyvinyl butyrals, hydrocarbon resins, and mixtures thereof.

14. The coating layer according to claim 8, wherein said liquid is selected from alcohol ethoxylates, alcohol alkoxylates, phenol ethoxylates, nonyl phenol ethoxylates, amine ethoxylates, amide ethoxylates, alkylpolyglucosides, polyalcohols, polyoxylated alcohols, fatty acid esters, amine and amide derivatives, ethylene oxide/propylene oxide copolymers, silicone surfactants, and mixtures thereof.

15. A method for forming an anti-fingerprint coating on top of a substrate, comprising: (a) preparing a composition according to claim 1; (b) applying the composition on top of a substrate; and (c) curing or drying the composition to form a coating layer on top of the substrate.

16. A method for diffusing and fading fingerprints, comprising providing a coating layer according to claim 8 to contact the fingerprints.

17. A method for evaluating and improving the anti-fingerprint performance of a coating layer according to claim 8, comprising the steps of: (a) contacting fingerprints with the coating layer; (b) recording and calculating the decrease in the number of fingerprint droplets over time, and/or the decrease in the total area of fingerprints over time; and (c) evaluating and improving the performance of fingerprint fading according to the calculation results.

18. The method according to claim 16, wherein the number of fingerprint droplets decreases by more than 30% after 10 minutes, more than 52% after 1 hour, or more than 73% after 6 hours.

19. The method according to claim 16, wherein the total area of fingerprint droplets decreases by more than 1% after 10 minutes, more than 5% after 10 minutes, or more than 13% after 6 hours.

20. A method for evaluating and improving the anti-fingerprint performance of a coating layer according to claim 8, comprising (a) contacting water or oil with the coating layer to form a drop thereon; (b) recording and calculating the increase in the base diameter, the decrease in the height, and the decrease in the contact angle of the drop over time; and (c) evaluating and improving the performance of diffusion and fading according to the calculation results.

21. An article coated with a coating layer according to claim 8.

22. The article according to claim 21, wherein the article is selected from the group comprising consumer electronic devices including mobile phones, tablets, personal computers, laptop computers, electronic readers, music players, computer accessories, televisions, game consoles, global positioning system devices, wearable devices; as well as automotive parts; and home appliances.

Description

DESCRIPTION OF DRAWINGS

[0052] The above and other objectives, features, and advantages of the present invention will become more apparent to those of ordinary skill in the art by being described in embodiments thereof with reference to the accompanying drawings.

[0053] FIG. 1 is a cross-sectional schematic diagram of an exemplary coating layer applied on top of a substrate in accordance with an embodiment of the invention.

[0054] FIG. 2a shows a liquid drop that is about to be deposited onto an exemplary coating layer. FIG. 2b shows the drop sitting on top of an exemplary coating layer at the solid-liquid-air interface during the measurements of the drop height, base diameter, and contact angle.

[0055] FIGS. 3a-3c and 3d-3f show images of a water drop for Example 2 and Comparative Example 2 at times 0, 1, and 5 min, respectively. FIGS. 3g-3h show the normalized base diameter and normalized height of the water drop as a function of time for Example 2 and Comparative Example 2, respectively.

[0056] FIGS. 4a-4c and 4d-4f show images of a tetradecane (oil) drop for Example 2 and Comparative Example 2 at times 0, 1, and 5 min, respectively. FIGS. 3g-3h show the normalized base diameter and normalized height of the tetradecane drop as a function of time for Example 2 and Comparative Example 2, respectively.

[0057] FIGS. 5a-5c and 5d-5f show fingerprint images observed under optical microscope at a magnification of 5 at various times for Example 2 and Comparative Example 2, respectively.

[0058] FIGS. 6a and 6b show distribution of the fingerprint droplets at various times for Example 2 and Comparative example 2, respectively. FIGS. 6c and 6d show the number of fingerprint droplets and the total area of fingerprint droplets as a function of time for Example 2 and Comparative Example 2, respectively.

EXAMPLES

[0059] The following examples are offered to illustrate, but not to limit the claimed invention.

Preparation of Coating Compositions

Example 1

[0060] 146 g of a binder mixture (970-CJS-704, available from Akzo Nobel Coatings (Tianjin) Co. Ltd., comprising 100 g of binder, 40 g solvent, and 6 g of photoinitiator), 50 g of an ethoxylated alcohol with an HLB value of 10.5 (Berol 260, available from Akzo Nobel Surface Chemistry LLB), 50 g of a nanosilica dispersion (NanoBYK 3652, available from BYK-Chemie GmbH), 7 g of a fluorinated additive (Megaface RS-75, available from DIC Corporation), and 30 g of isopropyl alcohol were mixed and stirred for 10 minutes at room temperature. The resulting mixture was allowed to rest for 5 min.

Comparative Example 1

[0061] 146 g of a binder mixture coating solution (970-CJS-704, available from Akzo Nobel Coatings (Tianjin) Co. Ltd., comprising 100 g of binder, 40 g solvent, and 6 g of photoinitiator), 7 g of a fluorinated additive (Megaface RS-75, available from DIC Corporation), and 30 g of isopropyl alcohol were mixed and stirred for 10 minutes at room temperature. The resulting mixture was allowed to rest for 5 min.

Preparation of Coating Layers

Example 2

[0062] The coating composition obtained in Example 1 was applied on top of a polycarbonate substrate by spray coating. The coating was baked at 60 C. for 5 min before being cured twice by UV radiation at a line speed of 10 m/min and a light intensity of 1,000 mJ/cm.sup.2. The cured coating layer has a film thickness of about 20 m.

Comparative Example 2

[0063] The procedure of Example 2 was repeated except for using the coating composition obtained in Comparative Example 1.

Evaluation of Properties of Coating Layers

[0064] The coating layers obtained from Example 2 and Comparative Example 2 were evaluated in accordance with the following methods.

(a) Easy-Clean Performance Using Contact Angle Measurements and Diffusion Performance by Drop Analysis

[0065] Contact angle measurements were performed on the coating layers using an optical contact angle instrument OCA 20 from DataPhysics equipped with a digital camera and the SCA 20 software. First, a 4 L drop of deionized water was applied to a fresh area on the coating layer, and images of the drop were recorded at a speed of 4 frames per second for 5 min by the software. The procedure was repeated for a 4 L drop of tetradecane.

[0066] The drop images were analyzed using the SCA 20 software to determine the drop parameters like height, base diameter, and contact angle, as illustrated in FIG. 2b. These parameters can be normalized by dividing the value at a given time by that at time 0.

[0067] FIGS. 3a-3c and 3d-3f compare images of a water drop between Example 2 and Comparative Example 2 at times 0, 1, and 5 min, respectively. FIGS. 3g-3h compare the normalized base diameter and normalized height of the water drop as a function of time between Example 2 and Comparative Example 2, respectively. The initial water contact angles for Example 2 and Comparative Example 2 were similar, 106 and 108, respectively. These values were quite high, indicating high hydrophobicity or water repellency. Minimal change in the drop shape was observed for Comparative Example 2 over time. By comparison, for Example 2, the water drop was found to diffuse quickly, as indicated by the sharp increase in the base diameter and the rapid decrease in both the height and contact angle with time.

[0068] FIGS. 4a-4c and 4d-4f compare images of a tetradecane (oil) drop between Example 2 and Comparative Example 2 at times 0, 1, and 5 min, respectively. FIGS. 4g-4h compare the normalized base diameter and normalized height of the tetradecane drop as a function of time between Example 2 and Comparative Example 2, respectively. The initial tetradecane contact angles for Example 2 and Comparative Example 2 were similar, 63 and 60, respectively. These values were quite high, indicating relatively high oleophobicity and a good easy-clean performance. No change in the drop shape was observed for Comparative Example 2 over time. By comparison, for Example 2, the tetradecane drop was found to diffuse slowly, as indicated by the slight increase in the base diameter and the small decrease in both the height and contact angle with time.

(b) Measurement of Fingerprint-Fading Performance

[0069] Fingerprints were deposited onto the coating layer, and images were recorded as a function of time under an optical microscope with a magnification of 5 using a digital camera. Comparison of the images in FIGS. 5a-5c and 5d-5f indicates shrinking and fading of some fingerprints over time in Example 2. By comparison, no change was observed for Comparative Example 2.

[0070] Analysis of the images was performed using the ImageJ 1.46r software from National Institute of Health. The number and the total area of the fingerprint droplets were measured and calculated using standard processing and particle measurement tools available in ImageJ. FIGS. 6a and 6b show the distribution of the fingerprint droplets at various times obtained from the calculation results for Example 2 and Comparative example 2, respectively. For Example 2, the fingerprint droplets were found to shrink, and small droplets were found to disappear with time. By comparison, little change was observed for Comparative Example 2 in FIG. 6b. FIGS. 6c and 6d compare the number of fingerprint droplets and the total area of fingerprint droplets as a function of time for Example 2 and Comparative Example 2, respectively. The fading performance can be quantitatively represented by both the ratio of the number of the fingerprint droplets at a given time to that at time 0 and the ratio of the total area of the fingerprint droplets at a given time to that at time 0. For Example 2, the number of fingerprint droplets was found to decrease by more than 30% (or to a ratio of 0.70), 52% (or to a ratio of 0.48), and 73% (or to a ratio of 0.27) after 10 min, 1 h, and 6 h, respectively, and the total area of fingerprint droplets was found to decrease by more than 1% (or to a ratio of 0.99), 5% (or to a ratio of 0.95), and 13% (or to a ratio of 0.87) after 10 min, 1 h, and 6 h, respectively. By comparison, minimal change was observed for Comparative Example 2 in FIGS. 6c and 6d.