Intumescent coating composition

Abstract

An intumescent coating composition that includes an epoxy resin binder, an epoxy reactive diluent, a curing agent and an acid catalyst. The curing agent includes a mixture of polyimide, polyetheramine, and an amine functional monomer, wherein the amine multifunctional monomer is different from the polyetheramine. The acid catalyst is effective to form a phosphoric acid on thermal decomposition. The coating composition has a viscosity of between 20,000 and 140,000 mPa/s at 20 C. and shear rate 1.5 s.sup.1 when measured within 1 minute of mixing the components. The invention also includes a coated substrate having the intumescent coating composition coated on at least a portion thereof.

Claims

1. An intumescent coating composition comprising: an epoxy resin binder, an epoxy reactive diluent, a curing agent, and an acid catalyst, wherein the curing agent is comprised of a mixture of polyamide, polyetheramine, and an amine multifunctional monomer, wherein the amine multifunctional monomer is different from the polyetheramine, and wherein the acid catalyst is effective to form a phosphoric acid on thermal decomposition, and wherein the coating composition has a viscosity of between 20,000 and 140,000 mPa/s at 20 C. and shear rate 1.5 s.sup.1 when measured within 1 minute of initial mixing.

2. An intumescent coating composition according to claim 1, wherein the epoxy resin binder comprises a Bisphenol diglycidyl ether epoxide resin.

3. An intumescent coating composition according to claim 1, wherein the epoxy reactive diluent comprises a diglycidyl ether of an aliphatic alcohol.

4. An intumescent coating composition according to claim 1, wherein the polyamide of the curing agent comprises a polyamidoimidazoline.

5. An intumescent coating composition according to claim 1, wherein the polyetheramine of the curing agent comprises a polyether backbone selected from polypropylene glycol and/or polyethylene glycol.

6. An intumescent coating composition according to claim 1, wherein the amine multifunctional monomer of the curing agent comprises a polyamine.

7. An intumescent coating composition according to claim 1, wherein the coating composition comprises from 1 to 60 wt % of the epoxy resin binder based on the total solid weight of the coating composition.

8. An intumescent coating composition according to claim 1, wherein the coating composition comprises from 1 to 30 wt % of the epoxy reactive diluent based on the total solid weight of the coating composition.

9. An intumescent coating composition according to claim 1, wherein the coating composition comprises from 1 to 15 wt % of polyamide based on the total solid weight of the composition.

10. An intumescent coating composition according to claim 1, wherein the coating composition comprises from 0.1 to 10 wt % of polyetheramine based on the total solid weight of the coating composition.

11. An intumescent coating composition according to claim 1, wherein the coating composition comprises from about 0.1 to 10 wt % of amine multifunctional monomer based on the total solid weight of the coating composition.

12. An intumescent coating composition according to claim 1, wherein the coating composition is formed from two component compositions, wherein the first component composition comprises the epoxy resin binder and the second component composition comprises the curing agent.

13. A coated substrate, coated on at least a portion thereof with an intumescent coating composition, the intumescent coating composition comprising: an epoxy resin binder, an epoxy reactive diluent, a curing agent, and an acid catalyst, wherein the curing agent is comprised of a mixture of polyamide, polyetheramine and an amine multifunctional monomer, wherein the amine multifunctional monomer is different from the polyetheramine, and wherein the acid catalyst is effective to form a phosphoric acid on thermal decomposition, and wherein the coating composition has a viscosity of between 20,000 and 140,000 mPa/s at 20 C. and shear rate 1.5 s.sup.1 when measured within 1 minute of initial mixing.

14. A steel or concrete substrate coated on at least a portion thereof with an intumescent coating composition, the intumescent coating composition comprising: an epoxy resin binder, an epoxy reactive diluent, a curing agent, and an acid catalyst, wherein the curing agent is comprised of a mixture of polyamide, polyetheramine and an amine multifunctional monomer, wherein the amine multifunctional monomer is different from the polyetheramine, and wherein the acid catalyst is effective to form a phosphoric acid on thermal decomposition, and wherein the coating composition has a viscosity of between 20,000 and 140,000 mPa/s at 20 C. and shear rate 1.5 s.sup.1 when measured within 1 minute of initial mixing.

15. A method of increasing the passive fire protection of a substrate, comprising applying an intumescent coating composition thereto, the intumescent coating composition comprising: an epoxy resin binder, an epoxy reactive diluent, a curing agent, and an acid catalyst, wherein the curing agent is comprised of a mixture of polyamide, polyetheramine and an amine multifunctional monomer, wherein the amine multifunctional monomer is different from the polyetheramine, and wherein the acid catalyst is effective to form a phosphoric acid on thermal decomposition, and wherein the coating composition has a viscosity of between 20,000 and 140,000 mPa/s at 20 C. and shear rate 1.5 s.sup.1 when measured within 1 minute of initial mixing.

Description

EXAMPLES

Coating Compositions

(1) Coating compositions 1 and 2 and comparative coating composition 1 were prepared from two component compositions. Both component compositions were produced using a dispermat-type high speed dissolver. The solid materials were introduced into the liquid materials whilst stirring at low speed and subsequently grinded at high speed at 45 C. until the fineness of the ground pigment was below 120 m (microns). Grind fineness was measured using a Hegmann-type grindometer. Prior to application, the two component compositions were mixed until homogeneous.

(2) Coating compositions 1 and 2 and comparative coating composition 1 were prepared according to the formulations in Table 1. All amounts are given in parts by weight (pbw).

(3) TABLE-US-00001 TABLE 1 Formulations of Coating Compositions Comparative Coating Coating Coating Composition Composition Composition 1 2 1 FIRST COMPONENT COMPOSITION Bisphenol A-type 18.29 16.25 23.04 Epoxy resin binder diglycidyl ether 1,6-Hexanediol 7.17 Epoxy reactive diglycidyl ether diluent Neopentyl glycol 7.04 Epoxy reactive diglycidyl ether diluent Micronised amide wax 0.34 0.27 0.29 Rheology modifier Castor oil derivative 0.17 0.13 0.14 Rheology modifier Titanium dioxide 10.55 13.54 10.15 Pigment Pentaerythritol 9.63 10.02 6.18 Carbon donor Ammonium 29.88 28.16 28.75 Acid catalyst polyphosphate Benzyl alcohol 5.15 5.65 5.52 Plasticiser SECOND COMPONENT COMPOSITION Polyamide AEW 95 4.70 5.99 11.29 Curing agent Polyetheramine AEW 57 2.02 2.71 Curing agent Isophoronediamine 2.43 1.02 Curing agent Fumed silica 0.19 0.37 0.10 Rheology modifier Bentonite clay 0.02 0.05 0.01 Rheology modifier Melamine 9.46 8.80 9.20 Blowing agent Pentaerythritol 3.87 Carbon donor Benzyl alcohol 1.46 Plasticiser

(4) The properties of the coating compositions were tested via the following methods. Results are shown in Table 2.

(5) Preparation of Test Substrates:

(6) Coatings were applied to 150753 mm steel panels at 8 mm dry film thickness and cured for 1 week at ambient conditions and a further week at 40 C. The samples were burnt with a propane torch for 3 minutes from a distance of 15 cm.

(7) The coating compositions were tested for char density, char cracking, char shrinking and char adhesion. Viscosity, gel-time and expansion factor of the coating compositions were also measured according to the procedures below.

(8) Viscosity:

(9) Viscosity was evaluated according to ASTM D2196-10 using Brookfield RV spindles s7 at 6 rpm and shear rate 1.5 s.sup.1. Viscosity was measured within 1 minute of initial mixing of the components at 20 C.

(10) Gel-Time:

(11) Gel-time refers to the time taken for the initial viscosity to increase by 100%. Gel-time was evaluated according to ASTM D2196-10 using Brookfield RV spindles s7 at 6 rpm and shear rate 1.5 s.sup.1.

(12) Expansion Factor:

(13) The expansion factor of the coating compositions was calculated using the following formula:

(14) $\frac{\mathrm{Char}\mathrm{height}\mathrm{after}\mathrm{torch}\mathrm{test}}{\mathrm{Initial}\mathrm{dry}\mathrm{film}\mathrm{thickness}}$

(15) Char Density:

(16) Char density was evaluated according to the quantity and size of air pockets throughout the char and using a rating of 1 to 5, with 5 being the best.

(17) Char Cracking:

(18) Char cracking was evaluated according to the quantity and extent of cracking to appear on the surface of the coating and using a rating of 1 to 5, with 5 being the best.

(19) Char Shrinking:

(20) Char shrinking was evaluated according to the level of shrinking of the char from the edges of the panel in the horizontal plane and using a rating of 1 to 5, with 5 being the best.

(21) Char Adhesion:

(22) The char adhesion of the coating composition was evaluated according to the level of peeling from the panel and using a rating of 1 to 5, with 5 being the best.

(23) The results are shown in Table 2, below.

(24) TABLE-US-00002 TABLE 2 Test Results Comparative Coating Coating Coating Composition 1 Composition 2 Composition 1 Viscosity (mPa/s) 67,000 31,000 >150,000 Gel-time (min) 110 77 280 Expansion factor 13 17 9 Char density 5 4 4 Char cracking 4 3 3 Char Shrinking 4 3 2 Char Adhesion 4 3 3

(25) The results demonstrate that the intumescent coating compositions according to the present invention have lower viscosity, shorter gel times allowing for faster drying and improved char expansion factor and physical properties than coatings known in the art.

(26) 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.

(27) 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, expect combinations where at least some of such features and/or steps are mutually exclusive.

(28) 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.

(29) 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.