A Coating Composition

Abstract

An overcoatable primer coating composition comprising i) a solvent-borne epoxy functional acrylic binder formed from glycidyl methacrylate and at least one further ethylenically unsaturated monomer; and ii) a crosslinker comprising a polyamine. The invention extends to a coating system comprising the overcoatable primer coating composition and an overcoat coating composition.

Claims

1. An overcoatable primer coating composition comprising i) a solvent-borne epoxy functional acrylic binder formed from glycidyl methacrylate and at least one further ethylenically unsaturated monomer; and ii) a crosslinker comprising a polyamine.

2. A coating composition according to claim 1, wherein the glycidyl methacrylate and at least one further ethylenically unsaturated monomer represents at least 80% by weight of the monomers that form the solvent-borne epoxy functional acrylic binder.

3. A coating composition according to either of claim 1, wherein the at least one further ethylenically unsaturated monomer comprises styrene.

4. A coating composition according to claim 3, wherein the glycidyl methacrylate and styrene monomers represent at least 80% by weight of the monomers that form the solvent-borne epoxy functional acrylic binder.

5. A coating composition according to claim 1, which coating composition further comprises a corrosion inhibiting additive.

6. A coating composition according to claim 5, wherein the corrosion inhibiting additive comprises a compound of magnesium.

7. A coating composition according to claim 1, which coating composition further comprises an adhesion promoting additive.

8. A coating composition according to claim 7, wherein the adhesion promoting additive comprises an organo-functional silane material.

9. A coating composition according to claim 1, wherein the binder comprises 10 to 99.9% by weight of the solvent-borne epoxy functional acrylic binder and 90 to 0.1% by weight of a further binder.

10. A coating composition according to claim 9, wherein the further binder comprises an epoxy functional binder.

11. A coating composition according to claim 10, wherein the binder comprises 10 to 100% by weight of the solvent-borne epoxy functional acrylic binder and 90 to 0% by weight of the further binder comprising an epoxy functional binder.

12. (canceled)

13. A coating system comprising an overcoatable primer coating composition and an overcoat coating composition, the overcoatable primer coating composition comprising i) a solvent-borne epoxy functional acrylic binder formed from glycidyl methacrylate and at least one further ethylenically unsaturated monomer; and ii) a crosslinker comprising a polyamine.

14. A marine vessel or marine structure coated on at least a portion thereof with a coating system according to claim 13.

15. A coating system comprising an overcoatable primer coating composition and an overcoat coating composition, the overcoatable primer coating composition comprising i) a solvent-borne epoxy functional acrylic binder formed from glycidyl methacrylate and at least one further ethylenically unsaturated monomer; and ii) a crosslinker comprising a polyamine, wherein the overcoat coating composition is a marine paint composition.

16. An aircraft coated on at least a portion thereof with a coating system according to claim 13.

17. A coating system comprising an overcoatable primer coating composition and an overcoat coating composition, the overcoatable primer coating composition comprising i) a solvent-borne epoxy functional acrylic binder formed from glycidyl methacrylate and at least one further ethylenically unsaturated monomer; and ii) a crosslinker comprising a polyamine, wherein the overcoat coating composition is an aerospace paint composition.

Description

EXAMPLES

Example 1

Preparation of GMA/Acrylic Resin

[0102] An epoxy functional acrylic binder formed from glycidyl methacrylate and styrene was synthesised. The polymerisation was carried out in a 2 litre, 4-necked reaction flask equipped with heating, cooling, a thermocouple, stirring via a motor-driven steel stir blade and a cooled reflux condenser. A nitrogen flow was applied to the reaction flask at a rate of 0.2 standard cubic feet (scft)/minute to provide an inert atmosphere. 27.41 parts by weight A-100 and 0.2 parts by weight Dowanol PM glycol ether (available from The Dow Chemical Company) were charged added to the reaction flask and heated to 158 C. 4.09 parts by weight di-t-amyl peroxide and 6.13 parts by weight Dowanol PM glycol ether (available from The Dow Chemical Company) were then added to the reaction flasks over a period of 180 minutes, followed by 55.21 parts by weight styrene and 6.13 parts by weight glycidyl methacrylate over a period of 150 minutes. The reaction vessel was then held at a temperature of 158 C. for 30 minutes. Then 0.31 parts by weight di-t-amyl peroxide and 0.61 parts by weight Dowanol PM glycol ether (available from The Dow Chemical Company) were added to the reaction flask over a period of 30 minutes. The temperature of the reaction flask was held at 158 C. for an additional hour and then allowed to cool to <40 C. The resin was discharged from the reaction flask into unlined metal cans.

[0103] The resultant resin has a solids content of 68.4 wt %, a viscosity of 4,500 Centipoise as measured in accordance with ASTM method D-1545 using a bubble viscometer, an epoxy equivalent weight of 2,262 as measured in accordance with ASTM D1652 (Test method B) and a number-average molecular weight of 2,230 Da as measured using gel permeation chromatography (also known as size exclusion chromatography) according to ASTM D6579-11. A sample stored at a temperature of 48.8 C. for one month remained liquid.

Examples 2-5

[0104] Example primer coating formulations according to the present invention (Examples 2, 3, 4 and 5) and Comparative Examples 1 and 2 were prepared as displayed in Table 1, below. All amounts are given in parts by weight. The coatings were prepared as typical two component (2K) compositions. Two pre-mixed pigmented components, one containing the epoxy-functional acrylic binder and the other the crosslinker(s) were mixed together with a pneumatic air mixer at moderate speeds to homogenize the container for 1-2 minutes.

TABLE-US-00001 TABLE 1 Comparative Comparative Example 2 Example 3 Example 4 Example 5 Example 1 Example 2 Epoxy-functional 36.67 22.03 24.99 13.1 acrylic binder example 1.sup.1 Crosslinker.sup.2 7.12 8.54 9.71 10.19 10.69 10.69 Crosslinker.sup.3 4.72 5.67 6.45 6.75 7.10 7.10 Crosslinker.sup.4 0.65 0.65 0.65 0.65 0.65 0.65 Further Binder.sup.5 9.29 16.74 12.68 19.95 27.94 27.94 Further Binder.sup.6 3.025 3.63 4.13 4.32 4.54 4.54 Corrosion 17.51 17.51 17.51 17.51 26.07 17.51 Inhibiting additive.sup.7 Pigment.sup.8 9.46 9.44 9.44 9.44 9.44 9.44 Adhesion promoter.sup.9 0.82 0.82 0.82 0.82 0.82 0.82 Solvent.sup.10 25.84 25.84 25.84 25.84 25.84 25.84 Solvent.sup.11 4.86 4.86 4.86 4.86 4.86 4.86 Solvent.sup.12 33.41 33.41 33.41 33.41 33.41 33.41 .sup.168.4% solids .sup.2Ancamine 2569, 90% solids, available from Air Products and Chemicals, Inc. .sup.3Ancamine 2432, 100% solids, available from Air Products and Chemicals, Inc. .sup.4Ancamine K-54, 100% solids, available from Air Products and Chemicals, Inc. .sup.5Epon 828, available from Momentive Performance Materials Inc. .sup.6Epon TM 8111, available from Momentive Performance Materials Inc. .sup.7Magnesium oxide (MgO), 100% solids, with an average particle size of 20 nm and a surface area of 50 m.sup.2/g. .sup.8Ti-Pure R-706, 100% solids .sup.9Silquest* A-187, available from Momentive Performance Materials Inc. .sup.10Butyl alcohol .sup.11Amsco Solv 1420 .sup.12Oxsol 100

Test Methods

Test Panel Preparation:

[0105] The coating samples were applied onto one of three substrates: (A) a commercially available 2024-T3 bare aluminium panel abraded until surface oxidation was removed using EAC-8 (a metal conditioner available from PPG Aerospace Surface Solutions); (B) a commercially available 2024-T3 bare aluminium panel pre-treated with Alodine 1200S (a hexavalent chromium-containing conversion coating available from Henkel Corporation); or (C) a 7075-T6 clad aluminium panel abraded until surface oxidation was removed using EAC-8 and EAP-9 (metal conditioners available from PPG Aerospace Surface Solutions). The coatings were sprayed onto the substrates immediately following mixing using conventional air spray equipment.

Salt Spray Test:

[0106] Salt spray resistance was tested as described in ASTM B117. The coated panels were scribed with a knife to expose the bare metal substrate. The scribed panel was placed into a test chamber where an aqueous salt solution was continuously misted onto the panel. The chamber was maintained at a constant temperature of 33 to 36 C. The coated substrate was exposed to the salt spray environment for 500 to 1000 hours. After exposure, the coated panels were removed from the test chamber and evaluated for corrosion along the scribe.

Visual Blisters:

[0107] The panels were evaluated for face blistering in accordance with ASTM D714-87.

TABLE-US-00002 TABLE 2 % % No. No. Sub- Scribe Dark Scribe Face strate Corrosion Scribe Blisters Blisters Comments Exam- A 10 70 2.5 0 small ple 2 B 12.5 70 0 0 C 12.5 77.5 31 (1*, 1.sup.) 0 microblis- ter cluster Exam- A 15 80 12 0 tiny ple 3 B 15 80 0 0 C 12.5 85 31 (1*, 1.sup.) 0 microblis- ter cluster Exam- A 12.5 82.5 1 0 ple 4 B 10 85 0 0 C 10 82.5 31 (1*, 1.sup.) 7.5 microblis- ter cluster Exam- A 10 90 3 0 tiny ple 5 B 22.5 90 0 0 C 22.5 90 31 (1*, 1.sup.) 0 microblis- ter cluster Compar- A 10 95 1.5 0 tiny ative B 25 95 0.5 0 tiny Exam- C 25 95 31 (1*, 1.sup.) 0 pulled ple 1 1008 Compar- A 25 95 6.5 0 tiny ative B 25 95 2.5 0 tiny Exam- C 25 95 31 (1*, 1.sup.) 0 pulled ple 2 1008 A - Substrate = 2024 T3 Bare, Pre-treatment = EAC-8 Abrade B - Substrate = 2024 T3 Bare, Pre-treatment = Alodine 1200S C - Substrate = 7075 T6 Clad, Pre-treatment = EAC-8 Abrade/EAP-9 *Number of scribe blisters > 1/16 to < .sup.Number of scribe blisters >

[0108] The results show that the coating compositions according to the present invention (examples 2 to 5), which comprise an epoxy-functional acrylic binder, have greater resistance to corrosion compared to the comparative examples 1 and 2.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.