Pull Tabs for Food and/or Beverage Cans

Abstract

A pull tab for a food and/or beverage can coated on at least a portion thereof with a coating composition comprising: (a) a binder comprising a polyester material, (b) a phenolic crosslinker, and (c) an amino crosslinker, 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 pull tab for a food and/or beverage can coated on at least a portion thereof with a coating composition comprising: (a) a binder comprising a polyester material, (b) a phenolic crosslinker, and (c) an amino crosslinker, 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 pull tab according to claim 1, wherein the binder comprising a polyester material (a) is present in an amount of between 30 to 80 wt %.

3. A pull tab according to claim 1, wherein the phenolic crosslinker (b) is present in an amount of between 5 to 20 wt %.

4. A pull tab according to claim 1, wherein the amino crosslinker (c) is present in an amount of between 5 to 40 wt %.

5. A pull tab according to claim 1, wherein the coating composition further comprises a catalyst.

6. A pull tab according to claim 1, wherein the catalyst is present in an amount of between 0.1 to 2 wt %.

7. A pull tab according to claim 1, wherein the coating composition is substantially free of dialkyl tin compounds including oxides or other derivatives thereof.

8. A pull tab according to claim 1, wherein the dry film thickness of the coating composition is between 1 m to 1 mm.

9. A food and/or beverage can comprising a pull tab according to claim 1.

10. (canceled)

11. A method for coating a pull tab on at least a portion thereof, the method comprising the step of coating the pull tab on at least a portion thereof with a coating composition comprising: (a) a binder comprising a polyester material, (b) a phenolic crosslinker, and (c) an amino crosslinker, 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).

12. A pull tab coating composition, the coating composition comprising: (a) a binder comprising a polyester material, (b) a phenolic crosslinker, and (c) an amino crosslinker, 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

Coating Example 1

[0113] A coating composition was prepared according to the formulation in Table 1. All amounts are given in parts by weight.

[0114] Briefly, the coating composition was prepared in a vessel equipped with stirring at ambient temperature. The dispersing or mixing blade of the vessel was approximately one third () of the diameter of the vessel itself. Item 1 was first added to the vessel and then item 2 was added under slow agitation. The stirring speed was then increased to approximately 2,000 rpm until a complete blend was achieved. After this, items 3, 4, 5, 6 were added to the vessel followed by items 7, 8, 9 and 10 under stirring at 1,500 rpm. The viscosity was finally adjusted with items 11 and 12.

TABLE-US-00001 TABLE 1 Formulation of coating example 1 Item No. Ingredient Amount/pbw 1 URALAC SH978 .sup.1 53.0 2 PHENODUR PR897 .sup.2 9.7 3 BAKELITE 6535 .sup.3 2.0 4 LUWIPAL 017 .sup.4 7.0 5 CYMEL 325 .sup.5 0.5 6 CYCAT 600 .sup.6 0.03 7 Lanco Wax 1780 .sup.7 0.1 8 TEGO Glide 4415 .sup.8 1.0 9 BYK 310 .sup.9 0.02 10 Xylene .sup.10 7.65 11 Butyl diglycol acetate (ABDG) .sup.11 10.0 12 SOLVESSO 150ND .sup.12 9.0 Total 100.0 .sup.1 polyester resin from DSM .sup.2 phenolic resin from Cytec Industries Inc. .sup.3 from Hexion Speciality Chemicals .sup.4 phenolic resin from Hexion Speciality Chemicals .sup.5 methylated melamine-formaldehyde resin from Allnex .sup.6 organic acid catalyst from Allnex .sup.7 PTFE-modified polyethylene wax from Lubrizol .sup.8 wetting agent from Evonik .sup.9 additive from BYK-Chemie .sup.10 solvent .sup.11 solvent .sup.12 solvent

[0115] Coating example 1 was applied to each of tinplate, tin-free steel (TFS) and electro-zinced metal panels. The coating was applied with either a roller coater or a bar coater. The applied film weight was between 4 and 6 grams per square metre (gsm) died coating weight. A single coat was applied. After application, the coating was dried for 16 to 20 seconds in a fan assisted oven at a temperature of 240-300 C.

Comparative Coating Example 1

[0116] The commercially available product PPG3975-601/A, a BPA epoxy cross linked coating, was applied to each of tinplate, tin-free steel (TFS) and electro-zinced metal panels. The coating was applied with either a roller coater or a bar coater. The applied film weight was between 4 and 6 grams per square metre (gsm) died coating weight. A single coat was applied. After application, the coating was dried for 16 to 20 seconds in a fan assisted oven at a temperature of 240-300 C.

[0117] Properties of coating example 1 and comparative coating example 1 were tested via the following methods. Results are shown in Table 2.

Test Methods

Blush Test in Water:

[0118] The coated panels were cut into 10 cm5 cm panels and then placed in a can containing water such that half of the panel was submerged in the water. The can was then placed in an autoclave and processed at 121 C. for 90 minutes. After this time, the panels were examined visually for blushing (i.e. whitening of the coating), blistering, discolouration and adhesion loss

Blush Test in Detergent:

[0119] The procedure as described above for the blush in water test was carried with the exception that detergent was added to the water to make a one percent solution. The detergent used was Teepol.

Wedge Bend:

[0120] A 10 cm4 cm coated panel was bent on a 6 mm steel rod to form a U-shaped strip 10 cm long and 2 cm wide. The U-shaped strip was then placed onto a metal block with a built in tapered recess. A 2 kg weight was dropped onto the recessed block containing the U-shaped strip from a height of 57 cm in order to from a wedge. The test piece was then immersed in a copper sulphate (CuSO.sub.4) solution acidified with hydrochloric acid (HCl) for 2 minutes, followed by rinsing with tap water. The sample was then carefully dried by blotting any residual water with tissue paper. The length of coating without any fracture was measured. The result was quoted in mm passed. The wedge bends were tested in triplicate and the average value was quoted.

Mobility Test:

[0121] Surface mobility (or lubricity) was measured using an ALTEK Model 9505 mobility/lubricity tester. The sample was mounted in the machine and a test sequence was initiated according to the manufacturer's instructions. The coefficient of friction, as determined from the test sequence, was quoted from the reading of the electronic analogue meter.

T-Bend:

[0122] This test was carried out according to ISO 17132:2007 (Paints and varnishesT-bend test). Briefly, a coated panel was bent, i.e. folded, over itself and then a 2 kg weight in the form of a hammer was dropped onto the panel from a height of 57 cm. The process was then repeated. The minimum number of times that the panel could be bent without cracking or loss of adhesion, i.e. flaking, of the coating occurring was quoted.

Blocking Test:

[0123] The coated panels were cut into a series of 10 cm10 cm and were piled one on top of the other with a weight appropriate to simulate the pressure applied on the material during real usage and storage. The weight used was 1 ton. The weight was applied for 16 hours at 40 C. After this time, the degree of difficulty required to separate the coated panels was evaluated visually.

TABLE-US-00002 TABLE 2 Test results of coating example 1 and comparative coating example 1 Coating example 1 Comparative coating example 1 Tinplate TFS Electrozinced Tinplate TFS Electrozinced Blush test in Pass Pass Pass Pass Pass Pass water Blush test in Pass Pass Pass Pass Pass Pass detergent Wedge Bend 80 86 70 77 80 65 Mobility Test 0.065 0.065 0.065 0.06 0.06 0.06 T-bend 3T 3T 3T 3T 3T 3T Blocking test Pass Pass Pass Pass Pass Pass

[0124] The results show that the coating compositions according to the present invention are an alternative, or represent an improvement, over those of the comparative examples.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.