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 diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE).

Claims

1-15. (canceled)

16. A substrate coated on at least a portion thereof with a powder coating composition, the powder coating composition comprising: a thermoset resin comprising an acid functional polyester material; a thermoplastic resin; and 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).

17. The substrate of claim 16, wherein the acid functional polyester material comprises the reaction product of a polyacid and a polyol.

18. The substrate of claim 17, wherein the polyacid comprises at least 50 mol % terephthalic acid and/or isophthalic acid based on the total number of moles of polyacid.

19. The substrate of claim 17, wherein the polyol comprises at least 10 mol % of neopentyl glycol based on the total number of moles of polyol.

20. The substrate of claim 17, wherein the ratio of polyacid to polyol is from 20:1 to 1:20.

21. The substrate of claim 16, wherein the acid functional polyester material is formed from a polyacid comprising succinic acid, glutaric acid, adipic acid, heptanoic acid, dodecanedioic acid or combinations thereof.

22. The substrate of claim 16, wherein the coating composition is substantially free of formaldehyde or sources thereof.

23. The substrate of claim 16, wherein the thermoplastic resin comprises epoxy resin, polyester resin, polyolefin resin, polyamide resin, polyurethane resin, polysiloxane resin, acrylic resin, and/or hydrocarbon resin.

24. The substrate of claim 16, wherein the crosslinker comprises a hydroxyalkylamide material, a hydroxyl functional alkyl polyurea material, and/or a carbodiimide resin.

25. The substrate of claim 16, wherein the substrate comprises metal, plastic, and/or laminate.

26. The substrate of claim 16, wherein the acid functional polyester material has an acid number of at least 25 mg KOH/g.

27. The substrate of claim 16, wherein the acid functional polyester material has a Tg of 50° C. to 100° C.

28. The substrate of claim 16, wherein the acid functional polyester material has a number average molecular weight of 1,000 to 20,000 Da.

29. The substrate of claim 16, wherein the acid functional polyester material has a weight average molecular weight of 5,000 to 20,000 Da.

30. The substrate of claim 16, wherein the acid functional polyester material has a melt viscosity at 200° C. of 10 to 50 Poise.

31. The substrate of claim 16, wherein the thermoplastic resin has a Tg of 40° C. to 80° C.

32. The substrate of claim 16, wherein the substrate forms at least a portion of a metal can, a plastic bottle, a plastic tube, a laminate, and/or flexible packaging.

33. The substrate of claim 16, wherein the substrate forms at least a portion of a monobloc aerosol can and/or tube.

34. The substrate of claim 16, wherein the substrate forms at least a portion of a food and/or beverage packaging.

35. A packaging coated on at least a portion thereof with a powder coating composition, the powder coating composition comprising: a thermoset resin comprising an acid functional polyester material; a thermoplastic resin; and 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).

36. A method for producing a powder coating composition, the method comprising: extruding a polymer mixture comprising a thermoset resin comprising an acid functional polyester material, a thermoplastic resin, and a crosslinker to form a thermoset powder; and grinding the thermoset powder to an average particle size of 5 to 300 microns.

37. The method of claim 36, further comprising dry blending the polymer mixture before extruding.

Description

EXAMPLES

Coating Composition 1

[0239] 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

Comparative Coating Composition 1

[0240] 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.

[0241] The properties of the coatings were tested via the following methods. Results are shown in Table 2.

Test Methods

[0242] 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).

[0243] 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.

[0244] 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).

[0245] 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 Pass-no blush Pass-no blush Enamel rater <3 mOhms <3 mOhms Direct impact >40 lbs >40 lbs Reverse impact >40 lbs >40 lbs Adhesion 5B 5B

[0246] The results show that the coating compositions according to the present invention perform as well, or better, than the coatings of the comparative examples.

[0247] 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.

[0248] 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.

[0249] 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.

[0250] 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.