Use of a coating on a chromium-free tinplate substrate

Abstract

Use of a coating composition on a chromium free tinplate substrate, the coating composition comprising: a polyester material, and benzoguanamine or a derivative thereof, 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 coating system on a chromium free tinplate substrate the coating system comprising: an undercoat coating composition comprising a polyester material, and a crosslinking material comprising benzoguanamine or a derivative thereof, wherein the crosslinking material further comprises a phenolic resin and an isocyanate resin; and an overcoat coating composition comprising a powder composition comprising a further polyester material, wherein the undercoat coating composition is substantially free of bisphenol A (BPA), bis phenol F (BPF), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

2. The coating system of claim 1, wherein the undercoat coating composition comprises at least 4.5 wt. % of the benzoguanamine or a derivative thereof based on the total solid weight of the undercoat coating composition.

3. The coating system of claim 1, wherein the powder coating composition is a thermoplastic coating composition.

4. A food or beverage can at least partially formed from a chromium free tinplate material, wherein the chromium free tinplate material is coated on at least a portion thereof with the coating system of claim 1.

5. The food or beverage can of claim 4, wherein the coating system is applied to a seam line or weld along the body of the food or beverage can.

6. The coating system of claim 1, when cured, has a flexibility of at least 20 mm as measured according to the draw and re-draw test method with processing in 1% salt (NaCl) solution in tap water at 130° C. for 60 minutes and a scratch resistance of at least 700 g as measured according to ISO Standard 1518-1:2011.

Description

EXAMPLES

(1) Coating Compositions

(2) Coating Composition 1

(3) Coating composition 1, containing a polyester material and benzoguanamine, was prepared according to the formulation in Table 1. All amounts are given in parts by weight (pbw) unless otherwise specified.

(4) Items 1 to 9 were loaded into a vessel equipped with a stirring system and mixed at a speed of 1,500 rpm. Items 10 and 11 were mixed separately and then added to the vessel under stirring. Finally, items 12 and 13 were added and the contents of the vessel were mixed thoroughly by stirring.

(5) The dry weight of benzoguanamine in coating composition example 1 is 5.65 wt % based on the total solid weight of coating composition example 1.

(6) TABLE-US-00001 TABLE 1 Formulation of Coating Composition 1 Coating Composition 1 1 Polyester resin .sup.1 57.16 2 Benzoguanamine 1 .sup.2 1.55 3 Benzoguanamine   2 .sup.3 2.95 4 Phenolic crosslinker 1 .sup.4 0.90 5 Phenolic crosslinker 2 .sup.5 8.97 6 Isocyanate crosslinker .sup.6 7.17 7 Solvent 1 .sup.7 10.36 8 Additive .sup.8 0.20 9 Wax .sup.9 2.66 10 Catalyst .sup.10 0.01 11 Solvent 1 .sup.7 0.09 12 Solvent 3 .sup.11 6.18 13 Solvent 4 .sup.12 1.80 Total 100 .sup.1 a linear polyester made from ethylene glycol, 2-methyl 1,3 propanediol, terephthalic acid and isophthalic acid and having an Mn of approx. 10,000 g/mol and a Tg of 56° C. .sup.2 MAPRENAL (RTM) BF891 available from INEOS .sup.3 CYMEL (RTM) 1123 available from available from Allnex .sup.4 DUREZ (RTM) 33356 available from Sumitomo .sup.5 CURAPHEN (RTM) 40-852 available from Bitrez .sup.6 VESTANAT (RTM) EP-B 1186A available from Evonik .sup.7 Xylene .sup.8 BYK088 available from BYK-Chemie .sup.9 Lanolin wax (15 wt % solution) .sup.10 NACURE (RTM) 5925, a blocked acid catalyst available from King Industries Inc. .sup.11 2-butoxyethylacetate .sup.12 Butyl acetate
Coating Composition 2

(7) Coating composition 2 is a commercial BPA NI powder side stripe available as PPG 5290-002/A from PPG.

(8) Coating Composition 3

(9) Coating composition 3 is a commercial BPA NI powder side stripe available as PPG 5290-003/A from PPG.

(10) Comparative Coating Composition 1

(11) Comparative coating composition 1 is a commercial BPA NI powder side stripe available as VECODUR (registered trade mark) VP1091 from Valspar.

(12) The properties of the coatings were tested by the following methods. The results are shown in Tables 2 to 5.

(13) Test Methods

(14) Test Panel Preparation:

(15) Coated panels were prepared by coating 4 cm×15 cm strips of tinplate sheet which had been pre-treated with either TATA passivation 505 (batch 20161076C), Arcelor passivation 555 (batch ANM64), TKS passivation 555 (batch WA230126id537) or US Steel passivation 555 (batch 1730062100100) in accordance with Tables 2 to 5. Each of these pre-treatments is a chrome-free passivation method. The undercoat, when present, was cured at 200° C. for 12 minutes. The powder overcoat was cured at 270° C., 295° C. or 320° C. for 45 seconds (in accordance with Tables 2 to 5).

(16) Powder Side Stripe Adhesion:

(17) Adhesion of the powder side stripe was tested the day after the test panels has been prepared. Using scissors, a V-shaped cut was made from the outside of the panel to the inside of the panel (with the sharp edge of the ‘V’ being on the inside of the panel). The substrate was then bent a number of times in opposite directions until the metal was broken. Once the metal had been broken, the powder side stripe was peeled, if possible, so as to remove it from the substrate. The peel angle was as close to 140° as possible. Loss of adhesion was measured in mm as the amount of powder side stripe that was peeled from the substrate.

(18) TABLE-US-00002 TABLE 2 Results on tinplate treated with TATA passivation 505 Tinplate Undercoat Powder Overcoat Adhesion Overcoat cured at 270° C. for 45 seconds TATA None Comparative Complete loss passivation coating of adhesion 505 composition 1 None Coating 2 mm Composition 2 None Coating 1 mm Composition 3 Coating Comparative 3 mm composition 1 Coating composition 1 Coating Coating 1 mm composition 1 Composition 2 Coating Coating 1 mm composition 1 Composition 3 Overcoat cured at 295° C. for 45 seconds TATA None Comparative Complete loss passivation coating of adhesion 505 composition 1 None Coating 1 mm Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 1 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 320° C. for 45 seconds TATA None Comparative Complete loss passivation coating of adhesion 505 composition 1 None Coating 2 mm Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 2 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3

(19) TABLE-US-00003 TABLE 3 Results on tinplate treated with Arcelor passivation 555 Tinplate Undercoat Powder Overcoat Adhesion Overcoat cured at 270° C. for 45 seconds Arcelor None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 3 mm ANM64 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 295° C. for 45 seconds Arcelor None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 0 mm ANM64 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 320° C. for 45 seconds Arcelor None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 0 mm ANM64 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3

(20) TABLE-US-00004 TABLE 4 Results on tinplate treated with TKS passivation 555 Tinplate Undercoat Powder Overcoat Adhesion Overcoat cured at 270° C. for 45 seconds TKS None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 2 mm WA230126id537 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 1 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 295° C. for 45 seconds TKS None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 0 mm WA230126id537 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 320° C. for 45 seconds TKS None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 0 mm WA230126id537 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3

(21) TABLE-US-00005 TABLE 5 Results on tinplate treated with US Steel passivation 555 Tinplate Undercoat Powder Overcoat Adhesion Overcoat cured at 270° C. for 45 seconds US steel None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 2.75 mm 1730062100100 Composition 2 None Coating 1 mm Composition 3 Coating Comparative 3 mm composition 1 Coating composition 1 Coating Coating 2 mm composition 1 Composition 2 Coating Coating 1 mm composition 1 Composition 3 Overcoat cured at 295° C. for 45 seconds US steel None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 3 mm 1730062100100 Composition 2 None Coating 0 mm Composition 3 Coating Comparative Complete loss composition 1 Coating of adhesion composition 1 Coating Coating 0 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3 Overcoat cured at 320° C. for 45 seconds US steel None Comparative Complete loss passivation coating of adhesion 555 composition 1 Batch None Coating 7 mm 1730062100100 Composition 2 None Coating 0 mm Composition 3 Coating Comparative 2 mm composition 1 Coating composition 1 Coating Coating 2 mm composition 1 Composition 2 Coating Coating 0 mm composition 1 Composition 3

(22) The results show that the coating compositions and/or systems according to the present invention have improved adhesion to the substrate compared to the comparative examples.

(23) 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 the public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(24) 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.

(25) 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.

(26) 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 or drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.