A COATING COMPOSITION COMPRISING A THERMOSET RESIN AND A THERMOPLASTIC RESIN

Abstract

A powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a crosslinker material, wherein the coating composition is substantially free of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidylether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

Claims

1. A powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a crosslinker material, 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 powder coating composition according to claim 1, wherein the acid functional polyester material comprises the reaction product of a polyacid and a polyol.

3. A powder coating composition according to claim 2, wherein the polyacid comprises at least 50 mol % terephthalic acid and/or isophthalic acid based on the total number of moles of polyacid.

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

5. A powder coating composition according to claim 2 or 3, wherein the polyol comprises at least 10 mol % of neopentyl glycol based on the total number of moles of polyol.

6. A powder coating composition according to any preceding claim, wherein the acid functional polyester material has an acid number (AN) of at least 25 mg KOH/g.

7. A powder coating composition according to any preceding claim, wherein the thermoplastic resin comprises epoxy resin, polyester resin, polyolefin resin, polyurethane resin, polysiloxane resin, acrylic resin, hydrocarbon resin or combinations thereof.

8. A powder coating composition according to claim 7, wherein the thermoplastic resin comprises polyolefin resin, acrylic resin or a combination thereof.

9. A powder coating composition according to claim 7 or 8, wherein the thermoplastic resin is provided in the form of a powder or in the form of a dispersion in a liquid carrier.

10. A powder coating composition according to any preceding claim, wherein the liquid carrier comprises water.

11. A powder coating composition according to any preceding claim, wherein the crosslinker comprises a hydroxyalkylamide material and/or a hydroxy functional alkyl polyurea material and/or a carbodiimide resin.

12. A method for producing a powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a crosslinker material, the method comprising the steps of: i) dispersing components (a), (b) and (c) in a liquid carrier, ii) drying the dispersion of step (i) to form a powder, and iii) grinding the powder of step (ii) to a particle size of 5 to 300 micron (m), 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. A metal substrate coated on at least a portion thereof with a thermoset powder coating composition, the powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a 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).

14. Food and/or beverage packaging coated on at least a portion thereof with a thermoset powder coating composition, the powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a 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).

15. A monobloc aerosol can and/or tube coated on at least a portion thereof with a thermoset powder coating composition, the powder coating composition comprising: a) a thermoset resin comprising an acid functional polyester material, b) a thermoplastic resin and c) a 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

[0232] Coating Composition 1

[0233] Coating composition 1, containing a thermosetting resin and two thermoplastic resins, was prepared according to the formulation in Table 1 and dried using an appropriate method. All amounts in Table 1 are given in parts by weight (pbw).

TABLE-US-00001 TABLE 1 Coating Composition 1 Coating Composition 1 Thermoplastic resin 1 .sup.1 24.57 Thermoplastic resin 2 .sup.2 49.14 Thermoset resin .sup.3 11.60 Crosslinker .sup.4 4.25 Pigment 1 .sup.5 2.46 Pigment 2 .sup.6 0.01 Filler .sup.7 4.80 Additive 1 .sup.8 0.24 Additive 2 .sup.9 0.09 Additive 3 .sup.10 2.83 Total 100.00 .sup.1 Acrylic dispersion (Acrylic dispersion with acid number 30, Mw of 10 k to 30 k; 30% solid dispersed in 70% water) .sup.2 Polyolefin dispersion (Polymeric dispersion from Michelman Products, ME 310) .sup.3 Acid functional polyester available from PPG Industries, 35 acid value, 100% solids polyester resin .sup.4 PRIMID XL552 available from Ems .sup.5 Titanium dioxide .sup.6 Aluminium dioxide available from Aerox .sup.7 BaSO.sub.4 available from CIMBAR .sup.8 Resiflow PL 200 a flow agent available from Estron Chemical .sup.9 Benzoin available from Sigma Aldrich .sup.10 Licowax C available from Clariant

[0234] Comparative Coating Composition 1

[0235] Comparative coating composition 1 is a polyester-based composition containing a thermoset resin (acid functional polyester available from PPG Industries, 35 acid value, 100% solids polyester resin), a crosslinker that reacts with acid groups, extender pigments and flow aids. Accordingly, comparative coating composition 1 contains thermoset resins only. The components were extruded via standard powder manufacturing methods and ground by standard methods.

[0236] The properties of the coatings were tested via the following methods. Results are shown in Table 2.

[0237] Test Methods

[0238] MEK rub test: The number of reciprocating rubs required to remove the coating was measured using a ball of cotton wool soaked in methyl ethyl ketone (MEK).

[0239] Blush test: Resistance to blush, which is white colouration of the film caused by water penetration and entrapment was measured by the following method. The coated panels were sterilised in an autoclave for 1 hour at 130 C. in a 1% solution of arylsulphosuccinate detergent in water and then the film was then observed visually.

[0240] Enamel rator: A 1 kg weight was dropped onto a coated panel from a 1 meter height to strike an indentation. The test was repeated two times under the same conditions on two individual cans. The integrity of the coating was measured using a WACO Enamel Rater Instrument and a 1% NaCl solution and reported in milliohms (mOhm).

[0241] Direct impact: Both tests use a Paul N Garnder Co. falling dart test on metal panels and references ASTM D 2794-93 test procedure. After the coating is impacted either directly or reverse impacted it is further subjected to Enamel Rator testing.

TABLE-US-00002 TABLE 2 Test Results Comparative Coating Coating Composition 1 Composition 1 MEK double rubs 100 >100 Blush Passno blush Passno blush Enamel rater <3 mOhms <3 mOhms Direct impact >40 lbs >40 lbs Reverse impact >40 lbs >40 lbs Adhesion 5 B 5 B

[0242] The results show that the coating compositions according to the present invention perform as well, or better, than the coatings of the comparative examples.

[0243] 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.

[0244] 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.

[0245] 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.

[0246] 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.