A COATING COMPOSITION COMPRISING A POWDER DISPERSED IN A LIQUID CARRIER

Abstract

A metal substrate being coated on at least a portion thereof with a liquid coating composition comprising a powder component dispersed in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier is less than 15 microns (m); wherein the powder component comprises a thermoset resin; wherein the thermoset resin comprises an acid functional polyester material; and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

Claims

1. A metal substrate being coated on at least a portion thereof with a liquid coating composition comprising a powder component dispersed in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier is less than 15 microns (m); wherein the powder component comprises a thermoset resin; wherein the thermoset resin comprises an acid functional polyester material; and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

2. A metal substrate according to claim 1, wherein the acid functional polyester material comprises the reaction product of a polyacid and a polyol.

3. A metal substrate according to claim 2, wherein the acid functional polyester is formed from a polyacid comprising succinic acid, glutaric acid, adipic acid, heptanoic acid, dodecanedioic acid or combinations thereof.

4. A metal substrate according to any of claims 1 to 3, wherein the acid functional polyester material has an acid number (AN) of at least 25 mg KOH/g.

5. A metal substrate according to any of claims 1 to 4, wherein the acid functional polyester material has a Tg from 20 C. to 150 C.

6. A metal substrate according to any preceding claim, wherein the powder component further comprises a thermoplastic resin.

7. A metal substrate according to claim 6, wherein the thermoplastic resin comprises a polyolefin resin, an acrylic resins or a combination thereof.

8. A metal substrate according to any preceding claim, wherein the powder component further comprises a crosslinker material.

9. A metal substrate according to claim 8, wherein the crosslinker comprises a hydroxyalkylamide material and/or a hydroxy functional alkyl polyurea material and/or a carbodiimide resin.

10. A metal substrate according to any preceding claim, wherein the liquid carrier comprises water, an organic solvent, a mixture of water and one or more organic solvent(s) or a mixture of organic solvents.

11. A metal substrate according to claim 9, wherein the liquid carrier comprises water.

12. A method for producing a liquid coating composition comprising a powder component dispersed in a liquid component, comprising the steps of: a) providing a powder having an average particle size of at least 20 microns (m), and b) dispersing the powder of step a) in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier of step (b) is less than 15 microns (m) and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

13. Food and/or beverage packaging being coated on at least a portion thereof with a liquid coating composition comprising a powder component dispersed in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier is less than 15 microns (m); wherein the powder component comprises a thermoset resin; wherein the thermoset resin comprises an acid functional polyester material; and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

14. A monobloc aerosol can and/or tube being coated on at least a portion thereof with a liquid coating composition comprising a powder component dispersed in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier is less than 15 microns (m); wherein the powder component comprises a thermoset resin; wherein the thermoset resin comprises an acid functional polyester material; and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

15. Food and/or beverage packaging liquid coating composition, the liquid coating composition comprising a powder component dispersed in a liquid carrier, wherein the average particle size of the powder dispersed in the liquid carrier is less than 15 microns (m); wherein the powder component comprises a thermoset resin; wherein the thermoset resin comprises an acid functional polyester material; and wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

Description

EXAMPLES

Powder Example 1

[0253] Powder example 1 was prepared according to the formulation in Table 1 and by the following method. All amounts are given in parts by weight (pbw) unless otherwise specified.

[0254] The powder was prepared by pre-mixing the ingredients in a three-blade mixer rotating at 3,500 rpm. The pre-mix was then extruded in a 19 mm dual screw extruder operating at a temperature of 100 C. The extrudate was rapidly cooled and pressed into chip. The chip was micronised to an average particle size of 25 microns (m) using a Hosokawa Air-Classifying Mill (ACM).

TABLE-US-00001 TABLE 1 Formulation of powder example 1 Component Amount Polyester Resin .sup.1 94.2 (acid value of 35) Primid QM-1260 .sup.2 5.8 Total 100 .sup.1 acid functional polyester commercially available from PPG having an acid value of 35 and 100% solid .sup.2 -hydroxyalkylamide crosslinker available from EMS

Liquid Coating Example 2

[0255] Liquid coating example 2 was prepared according to the formulation in Table 2 and by the following method. All amounts are given in parts by weight (pbw) unless otherwise specified.

[0256] The liquid coating was prepared by combining all of the materials. This mixture was then milled with a Lau 200 Disperser for 8 hours and demonstrated a Hegman value of greater than 7.5, as determined by ASTM D1210-05. This corresponds to a particle size of less than 5 microns (m).

TABLE-US-00002 TABLE 2 Formulation of liquid coating example 2 Component Amount Deionised water 85.0 BYK-011 .sup.1 0.43 Triton GR-5 .sup.2 0.71 Disperbyk 190 .sup.3 4.38 Powder example 1 47.1 Bentone EW .sup.4 0.6 Total 138.21 .sup.1 Defoamer available from BYK .sup.2 Surfactant available from Dow .sup.3 Dispersing agent available from BYK .sup.4 Anti-settle agent available from Elementis

[0257] The properties of the coatings were tested via the following methods. Results are shown in Table 3.

[0258] Test panel preparation: Coated panels were obtained by drawing paints over zirconium treated 5182-H481 aluminum panels using a wire wound rod to obtain dry coating weights of 7.0 mg/square inch (msi). The coated panels were immediately placed into a one-zone, gas-fired, conveyor oven for 10 seconds and baked to a peak metal temperature of 232 C. The baked panels were immediately quenched in water upon exit from the oven. They were then dried and cut into smaller test panels.

Test Methods

[0259] MEK Double Rubs: The number of reciprocating rubs required to remove the coating was measured using a rag soaked in methyl ethyl ketone (MEK).

[0260] Wedge Bend Test: The flexibility of the coatings was evaluated with a wedge bend test. For this test, coated panels were cut into 2 inch by 4.5 inch pieces, with the substrate grain running perpendicular to the long length of the cut panel. They were then bent over a 0.25 inch metal dowel along the long length of the panel with the coated side facing out. The bent panels were then placed onto a block of metal where a wedge was pre-cut out of it with a taper of 0 to 0.25 inch along a 4.5 inch length. Once placed in the wedge, each bent panel was struck with a block of metal which weighed 2.1 kilograms from a height of 11 inches to form a wedge where one end of the coated metal impinged upon itself and a 0.25 inch space remained on the opposite end. The wedge bent panels were then placed into an aqueous solution of copper sulphate and hydrochloric acid for two minutes to purposely etch the aluminum panel in areas where the coatings failed and cracked. The etched wedge bent panels were then examined through a microscope at 10 power to determine how far the coating had cracked from the impinged end along the bent radii. Results are reported as the percentage of cracked area versus total length of the wedge bent panel.

[0261] Boiling Water Tests: The coatings were also evaluated for their ability to adhere to the aluminum panels and to resist blushing in four aqueous solutions as follows:

[0262] a) Dowfax Detergent Test: This test is designed to measure the resistance of a coating to a boiling detergent solution. The solution is prepared by mixing 5 grams of DOWFAX 2A1 (available from Dow Chemical) into 3,000 grams of deionized water. Coated strips are immersed into the boiling Dowfax solution for 15 minutes. The strips are then rinsed and cooled in deionized water, dried, and immediately rated for blush as described below.

[0263] b) Joy Detergent Test: This test is designed to measure the resistance of a coating to a hot 82 C. Joy detergent solution. The solution is prepared by mixing 30 grams of Ultra Joy Dishwashing Liquid (available from Procter & Gamble) into 3,000 grams of deionized water. Coated strips are immersed into the 82 C. Joy solution for 15 minutes. The strips are then rinsed and cooled in deionized water, dried, and immediately rated for blush as described below.

[0264] c) Acetic Acid Test: This test is designed to measure the resistance of a coating to a boiling 3% acetic acid solution. The solution is prepared by mixing 90 grams of glacial acetic acid (available from Fisher Scientific) into 3,000 grams of deionized water. Coated strips are immersed into the boiling acetic acid solution for 30 minutes. The strips are then rinsed and cooled in deionized water, dried, and immediately rated for blush as described below.

[0265] d) Deionized Water Retort Test: This test is designed to measure the resistance of a coating to deionized water. Coated strips are immersed into the deionized water and placed in a steam retort for 30 minutes at 121 C. The strips are then cooled in deionized water, dried, and immediately rated for blush as described below.

[0266] Blush Resistance: Blush resistance measures the ability of a coating to resist attack by the various testing solutions described above. When the coated film absorbs the test solution, it generally becomes cloudy or looks white. Blush is measured visually using a scale of 1-10 where a rating of 10 indicates no blush and a rating of 0 indicates complete whitening of the film. Blush ratings of at least 6 are typically desired for commercially viable coatings. The coated panel tested was 510 cm and the testing solution covered half of the panel being tested such that a comparison between the blush of the exposed portion to the unexposed portion of the panel could be made.

[0267] Adhesion: Adhesion testing was performed to assess whether the coating adhered to the substrate. The adhesion test is performed according to ASTM D 3359 Test Method B, using Scotch 610 tape, available from 3M Company of Saint Paul, Minn. Adhesion was assessed visually and was rated on a scale of 1-10 where a rating of 10 indicates no adhesion failure, a rating of 9 indicates 90% of the coating remains adhered, a rating of 8 indicates 80% of the coating remains adhered, and so on.

TABLE-US-00003 TABLE 3 Test Results Liquid coating example 2 MEK Double Rubs 17 Wedge Bend (average % Spotty Failure) 12% a) Dowfax Blush 6 Adhesion 10 b) Joy Blush 6 Adhesion 10 c) Acetic acid Blush 4 Adhesion 10 d) Water Retort Blush 4 Adhesion 10

[0268] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0269] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0270] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0271] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.