WO2011075550A2 - D1417 bt radiation curable coatings for aerospace applications - Google Patents

Abstract

Urethane (meth)acrylate radiation curable coating compositions for coating the exterior surfaces of an aircraft are described and claimed. Certain of these compositions can be cured by exposure to light from ultraviolet mercury lamps. Others of these compositions can be cured by exposure to light for LEDs. The liquid radiation curable coatings have a viscosity between about 100 mPa-s and about 2500 mPa-s; and a cured film of the radiation curable coating has a tensile Modulus or Equilibrium Modulus of between about 100 MPa and about 650 MPa; an Elongation at break of between about 10% and about 30%; and a Pencil Hardness of between about B and F.

Description

D1417 BT Radiation Curable Coatings for Aerospace Applications

D 1417 BT Radiation Curable Coatings for Aerospace Applications

Cross-Reference to Related Patent Application

[0001] This patent application claims priority to U.S. Provisional Patent Application No. 61/287,538 filed on December 17, 2009, which is incorporated by reference in its entirety.

Field of the Invention

[0002] The present invention relates to radiation curable compositions for coating the external surfaces of aircraft and methods of formulating these compositions.

Background of the Invention

[0003] For purpose of this patent application the term "aerospace" is equivalent to the term "aircraft". Aircraft refers to airplanes and helicopters capable of terrestrial flight as opposed to spacecraft flight. Protective Coatings for Aircraft are well known in the art. See "Aerospace Coatings: A Survey of Aircraft Manufacturers and Coating Suppliers" by Cynthia Challener, JCT CoatingsTech, Contributing Writer, JCT CoatingsTech, October 2009, pages 40-43. In this article, it is stated, on page 40, "...the airline industry (commercial and military) has challenged aircraft

manufacturers to provide aircrafts protected with environmentally friendly, high performing durable coatings. Aircraft manufacturers then look to coatings suppliers for products that enable them to satisfy the airline companies' needs."

[0004] Aircraft use a protective coating system that is applied to the aircraft to minimize metal corrosion and maximize resistance of the exterior surface to a variety of aggressive environments and agents such as jet fuels, lubricating fluids, rain and salt water and sun exposure at low and high altitude. The coating system is also used to provide the desired color, infrared properties, impact resistance, and gloss to the exterior surface. Current protective coating systems often consist of multiple layers, two of which include a primer and a separate topcoat film, both individually applied to the aircraft. Primer coatings that meet current military specifications typically are epoxy resins pigmented with strontium chromate for corrosion protection. Topcoats that meet current military specifications typically are polyurethane resins with appropriate pigmentation to provide color, infrared properties, and suitable gloss. However, the current protective coating systems suffer from several distinct drawbacks. Chief amongst these is the inordinate amount of time it takes the coating to dry after application. This time consuming process makes it impossible to speed up the process of initial manufacture of an airplane and it also slows down repair and recoating of existing aircraft,

[0005] Accordingly there exists a need to develop coatings for aircraft that cure instantly while providing cured coatings with the desired combination of physical properties. It is desirable to provide a protective coating for military and commercial aircraft that can be applied and cured quickly, wherein the cured coatings have the desired combination of physical properties. It is also desirable to provide a method for painting an aircraft with such a protective coating system [0006] United States Published Patent Application 200801 18659, published on May 22, 2008 and is entitled "CORROSION-RESISTANT, CHROMIUM-FREE, SELF-PRIMING COATINGS CURABLE BY ULTRAVIOLET LIGHT ". The patent application describes and claims Corrosion-resistant, self-priming coatings that are curable by ultraviolet energy and methods for coating surfaces using such coatings have been provided. In an exemplary embodiment, a method for coating a surface includes formulating a chromium-free, self-priming coating, applying the chromium- free, self-priming coating to the surface, and curing the chromium-free, self-priming coating with ultraviolet light.

[0007] PCT Published Patent Application WO 2005/103121, entitled "Method for photocuring of Resin Compositions", assigned to DSM IP Assets B.V., describes and claims Methods for Light Emitting Diode (LED) curing of a curable resin

composition containing a photoinitiating system, characterized in that the highest wavelength at which absorption maximum of the photoinitiating system occurs (λ_Max PIS) is at least 20 nm below, and at most 100 nm below, the wavelength at which the emission maximum of the LED occurs (λ_LED). The invention in this PCT patent application relates to the use of LED curing in structural applications, in particular in applications for the lining or relining of objects, and to objects containing a cured resin composition obtained by LED curing. This invention provides a simple, environmentally safe and readily controllable method for (re)lining pipes, tanks and vessels, especially for such pipes and equipment having a large diameter, in particular more than 15 cm.

[0008] The foregoing shows that there is an unmet need to provide radiation curable coating compositions for aircraft to provide processes for coating aircraft with such coating compositions, and to provide coated aircraft comprising coatings prepared from such coating compositions. Summary Of The Invention

[0009] The first aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft, wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode (LED) having a wavelength from 100 nm to 900 nm, to provide a cured coating on the exterior surfaces of the aircraft, said cured coating having a top surface, said cured coating having a % Reacted Acrylate Unsaturation (%RAU) of 60 % or greater.

[0010] The second aspect of the instant claimed invention is a radiation curable aircraft coating composition of the first aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength of

from 100 nm to 300 nm;

from 300 nm to 475 nm; or

from 475 nm to 900 nm.

[0011] The third aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft, wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light generated using ultraviolet mercury lamps,

wherein the radiation curable coatings have a liquid viscosity between 100 mPa-s and 2500 mPa-s; and

a cured film of the radiation curable coating has

a tensile Modulus or equilibrium Modulus of between 100 MPa and 650 MPa; an Elongation at break of between 10 % and 30 %;

a Pencil Hardness (PR) of between B and F:

a Water Adhesion of at least 95 %;

a Water Resistance (APR) of from 0 to -2;

a Hydrocarbon T3 Resistance (APR) of between -2 to -4; and

a Skydrol LD4 resistance (APR) of between -4 to - 1.

[0012] The fourth aspect of the instant claimed invention is a radiation curable coating composition according to any one of claims 1-3, said composition comprising: at least one urethane (meth) acrylate oligomer; at least one reactive diluent monomer; and

at least one photoinitiator.

[0013] The fifth aspect of the instant claimed invention is a radiation curable coating composition of the fourth aspect of the instant claimed invention, wherein the photoinitiator is a Type I photoinitiator.

[0014] The sixth aspect of the instant claimed invention is a radiation curable coating composition of the fourth aspect of the instant claimed invention, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

[0015] The seventh aspect of the instant claimed invention is a radiation curable coating composition of any one of the first aspect through the sixth aspect of the instant claimed invention, in which at least 15 % of the ingredients in the coating are bio-based, rather than petroleum based, preferably at least 20 % of the ingredients, more preferably at least 25 % of the ingredients.

[0016] The eighth aspect of the instant claimed i nvention is a process for coating an aircraft comprising:

providing an aircraft, said aircraft possessing exterior surfaces in need of being coated;

coating said exterior surfaces of said aircraft with at least one coating composition, preferably a radiation curable coating composition according to any one of the first aspect through the seventh aspect of the instant claimed invention, and wherein said at least one coating composition comprises:

at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface of an aircraft, and

curing said uncured coated exterior surface of an aircraft by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode(LED) having a wavelength from 100 nm to 900 nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of 60 % or greater.

[0017] The ninth aspect of the instant claimed invention is the process of the eighth aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength of from 100 nm to 300 nm;

from 300 nm to 475 nm; or

from 475 nm to 900 nm.

[0018] The tenth aspect of the instant claimed invention is the process of eighth or ninth aspects of the instant claimed invention, wherein the photoinitiator is a Type I photoinitiator.

[0019] The eleventh aspect of the instant claimed invention is the process of the eighth or ninth aspects of the instant claimed invention, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

[0020] The twelfth aspect of the instant claimed invention is a coated aircraft obtainable by the process of any one of the eighth aspect through the eleventh aspect of the instant claimed invention.

[0021] The thirteenth aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft comprising:

at least one urethane (meth) acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light generated using ultraviolet mercury lamps wherein the radiation curable coatings have a

liquid viscosity between about 100 mPa s and about 2500 mPa-s; and

a cured film of the radiation curable coating has

a tensile Modulus or equilibrium Modulus of between about 100 MPa and about 650 MPa;

an Elongation at break of between about 10% and about 30%; a Pencil Hardness (PR) of between about B and F;

a Water Adhesion of at least about 95%;

a Water Resistance (APR) of from about 0 to -2;

a Hydrocarbon T3 Resistance (APR) of between about -2 to about -4; and a Skydrol LD4 resistance (APR) of between about -4 to about -1. The fourteenth aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft comprising:

at least one urethane (meth) acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode (LED) having a wavelength from about 100 nm to about 900nm, to provide a cured coating on the exterior surfaces of the aircraft, said cured coating having a top surface, said cured coating having a % Reacted Acrylate

Unsaturation (%RAU) of about 60% or greater.

The fifthteenth aspect of the instant claimed invention is a coated aircraft comprising an aircraft and at least one coating, wherein said at least one coating is produced by coating the exterior surface of said aircraft with at least one coating composition comprising:

at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface, and curing said uncured coated exterior surface of an aircraft by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode (LED) having a wavelength from about 100 nm to about 900nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of about 60% or greater. The sixteenth aspect of the instant claimed invention is a process for coating an aircraft comprising:

providing an aircraft, said aircraft possessing exterior surfaces in need of being coated;

coating said exterior surfaces of said aircraft with at least one coating composition, wherein said at least one coating composition comprises: at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface of an aircraft, and

curing said uncured coated exterior surface of an aircraft by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode(LED) having a wavelength from about 100 run to about 900nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of about 60% or greater.

[0022] The seventeenth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention wherein the light emitting diode (LED) has a wavelength from about 100 nm to about 300nm.

[0023] The eighteenth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength from about 300 nm to about 475 nm.

[0024] The nineteenth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength from about 475 nm to about 900nm.

[0025] The twentieth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type I photoinitiator.

[0026] The twenty-first aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor [0027] The twenty-second aspect of the instant claimed invention is a radiation curable aircraft coating composition of the thirteenth aspect of the instant claimed invention, wherein in which at least about 15% of the ingredients in the coating are bio-based, rather than petroleum based.

[0028] The twenty-third aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein in which at least about 15% of the ingredients in the coating are bio-based, rather than petroleum based.

[0029] The twenty-fourth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the thirteenth aspect of the instant claimed invention, wherein in which at least about 20% of the ingredients in the coating are bio-based, rather than petroleum based.

[0030] The twenty-fifth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein in which at least about 20% of the ingredients in the coating are bio-based, rather than petroleum based.

[0031] The twenty-sixth aspect of the instant claimed invention is a radiation curable aircraft coating composition of the thirteenth aspect of the instant claimed invention, wherein in which at least about 25% of the ingredients in the coating are bio-based, rather than petroleum based.

[0032] The twenty-seventh aspect of the instant claimed i nvention is a radiation curable aircraft coating composition of the fourteenth aspect of the instant claimed invention, wherein in which at least about 25% of the ingredients in the coating are bio-based, rather than petroleum based.

[0033] The twenty-eighth aspect of the instant claimed invention is a coated aircraft of the fifthteenth aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength from about 100 nm to about 300nm.

[0034] The twenty-ninth aspect of the instant claimed invention is a coated aircraft of the fifthteenth aspect of the instant claimed invention, wherein the light emitting diode (LED) has a wavelength from about 300 nm to about 475nm.

[0035] The thirtieth aspect of the instant claimed invention is a coated aircraft of the fifthteenth aspect of the instant claimed invention, wherein the light emi tting diode (LED) has a wavelength from about 475 nm to about 900nm. [0036] The thirty- first aspect of the instant claimed invention is a coated aircraft of the fifthteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type I photoinitiator.

[0037] The thirty-second aspect of the instant claimed invention is a coated aircraft of the fifthteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

[0038] The thirty-third aspect of the instant claimed invention is a process of the sixteenth aspect of the instant claimed invention, wherein the light emitting diode

(LED) has a wavelength from about 100 nm to about 300nm.

[0039] The thirty- fourth aspect of the instant claimed invention is a process of the sixteenth aspect of the instant claimed in vention, wherein the light emitting diode

(LED) has a wavelength from about 300 nm to about 475nm.

[0040] The thirty-fifth aspect of the instant claimed invention is a process of the sixteenth aspect of the instant claimed invention, wherein the light emitting diode

(LED) has a wavelength from about 475 nm to about 900nm.

[0041] The thirty-sixth aspect of the instant claimed invention is a process of the sixteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type

I photoinitiator.

[0042] The thirty-seventh aspect of the instant claimed invention is a process of the sixteenth aspect of the instant claimed invention, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

Detailed Description of the Invention

[0043] Throughout this patent application, the following terms have the indicated meaning: UVA radiation is radiation with a wavelength between about 320 and about 400nm. UVB radiation is radiation with a wavelength between about 280 and about 320nm. UVC radiation is radiation with a wavelength between about 100 and about 280nm.

[0044] As used herein, the term "renewable resource material" is defined as a starting material that is not derived from petroleum but as a starting material derived from a plant including the fruits, nuts and/or seeds of plants. These plant derived materials are environmentally friendly and biologically based materials. Thus, these starting materials are also frequently called "bio-based" materials or "natural oil" materials.

[0045] Further to the understood definition of "bio-based" , according to the FRSIA(Farm Security and Rural Investment Act), "biobased products" are products determined by the U.S. Secretary of Agriculture to be "commercial or industrial goods (other than food or feed) composed in whole or in significant part of biological products, forestry materials, or renewable domestic agricultural materials, including plant, animal or marine materials.

[0046] Biobased content may be determined by testing to ASTM Method D6866- 10, STANDARD TEST METHODS FOR DETERMINING THE BIOBASED CONTENT OF SOLID, LIQUID, AND GASEOUS SAMPLES USING

RADIOCARBON ANALYSIS. This method, similar to radiocarbon dating, compares how much of a decaying carbon isotope remains in a sample to how much would be in the same sample if it were made of entirely recently grown materials. The percentage is called the product's biobased content.

[0047] Persons of ordinary skill in the art of radiation curable coatings are aware of how to select ingredients and understand whether the ingredient is bio-based or petroleum based. What is different now is the sheer abundance of bio-based raw materials suitable for use in radiation curable coatings. For example, bio-based raw materials can be found in polyols and other ingredients.

[0048] The thirteenth aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft comprising:

at least one urethane (meth) acrylate oligomer;

at least one reactive diluent monomer; and at least one photoinitiator;

wherein tlie composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light generated using ultraviolet mercury lamps wherein the radiation curable coatings have a

liquid viscosity between about 100 mPa s and about 2500 mPa-s; and

a cured film of the radiation curable coating has

a Modulus of between about 100 MPa and about 650 MPa;

an Elongation at break of between about 10% and about 30%; a Pencil Hardness (PR) of between about B and F;

a Water Adhesion of at least about 95%;

a Water Resistance (APR) of from about 0 to -2;

a Hydrocarbon T3 Resistance (APR) of between about -2 to about -4; and a Skydrol LD4 resistance (APR) of between about -4 to about -1.

[0049] Urethane (meth)acrylate oligomers are well known in the art of radiation curable coatings for many substrates, including aircraft. See pages 3-36 of the reference text, MODERN COATING TECHNOLOGY, Edited by J.C. Colbert, copyright 1982 by Noyes Data Corporation, editor : J.C. Colbert where an article entitled "Radiation-Curable Urethane-Acrylate Coating Resins" is present.

[0050] Photoinitiators and Stabilizers are described in this article on pages 29-34. see also, "Effect of Structure on the Thermal Stability of Photocurable Urethane Acrylate Formulations", Shama and Tortorello, Journal of Applied Polymer Science, vol. 43, 699-707 (1991).

[0051] Urethane (meth)acrylate oligomers are based on stoichiometric combinations of di-isocyanates (DICs), polyols and some type of hydroxy- functional terminating species containing a UV -reactive terminus. Depending on the properties desired, different types of polyols are chosen. These polyols include, but are not limited to, polyether-polypropylene glycols(PPG) and polyether-polytetramethylene glycols (PTMG).

[0052] Petroleum-derived components such as polyester and polyether polyols pose several disadvantages. Use of such polyester or polyether polyols contributes to the depletion of petroleum-derived oil, which is a non-renewable resource. Also, the production of a polyol requires the investment of a great deal of energy because the oil needed to make the polyol must be drilled, extracted and transported to a refinery where it is refined and processed to purified hydrocarbons that are subsequently converted to alkoxides and finally to the finished polyols. As the consuming public becomes increasingly aware of the environmental impact of this production chain, consumer demand for "greener" products will continue to grow. To help reduce the depletion of petroleum-derived oil whilst satisfying this increasing consumer demand, it would be advantageous to partially or wholly replace petroleum-derived polyester or polyether polyols used in the production of urethane (meth)acrylate oligomers with renewable and more environmentally responsible components.

[0053] Further to the discussion of Bio-based products according to Plastics

Today: as published on this website:

http://www.plasticstoday.com/articles/com-based-isosorbide-could-serve-bpa- replacement on December 8th, 2010 : Agricultural processing giant Archer Daniels Midland Company has begun marketing isosorbide as part of its Evolution Chemicals product range. Isosorbide, derived from corn, is a potential alternative to the petroleum-based chemical Bisphenol A in plastics, epoxy resin and other applications.

[0054] Reactive Diluent Monomers are well known in the art of radiation curable coatings for optical fiber and many of the Reactive Diluent Monomers that are present in radiation curable coatings for optical fiber are also used in radiation curable coatings for aerospace applications. See pages 105 of the article entitled "Optical

Fiber Coatings" by Steven R. Schmid and Anthony F. Toussaint, DSM Desotech,

Elgin, Illinois, Chapter 4 of Specialty Optical Fibers Handbook, edited by Alexis

Mendez and T.F. Morse, ©2007 by Elsevier Inc., for a succinct summary of these types of reactive diluent monomers. See also, "Reactive Diluents and Properties of

Ultraviolet-Cured Polycarbonate Urethane Acrylates", Krongauz and Tortorello,

Journal of Applied Polymer Science, vol. 57, 1627-1636 (1995).

[0055] The composition of the present invention includes a free radical photoinitiator as urethane (meth)acrylate oligomers require a free radical

photoinitiator.

[0056] Typically, free radical photoinitiators are divided into those that form radicals by cleavage, known as "Norrish Type I" and those that form radicals by hydrogen abstraction, known as "Norrish type II". The "Norrish type II"

photoinitiators require a hydrogen donor, which serves as the free radical source. See pages 3-36 of the reference text, MODERN COATING TECHNOLOGY, Edited by J.C. Colbert, copyright 1982 by Noyes Data Corporation, editor : J.C. Colbert where an article entitled "Radiation-Curable Urethane-Acrylate Coating Resins" is present. Photoinitiators and Stabilizers are described in this article on pages 29-34.

[0057] To successfully formulate a radiation curable coating for aircraft, it is necessary to select the photoinitiator(s) present in the coating to match the light emitted from ultraviolet mercury lamps. Photoinitiators capable of being activated by light from ultraviolet mercury lamps are well known in the art of radiation curable coatings.

[0058] For light sources emitting in the 300 - 475nm wavelength range, especially those emitting about 365nm, about 390nm, or about 395nm, examples of suitable photoinitiators absorbing in this area include: benzoylphosphine oxides, such as, for example, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (Lucirin TPO from BASF) and 2,4,6-trimethylbenzoyl phenyl, ethoxy phosphine oxide (Lucirin TPO-L from BASF), bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropanone-l (Irgacure 907 from Ciba), 2-benzyl-2-(dimethylamino)-l-[4-(4-morphoIinyl) phenyl]-l- butanone (Irgacure 369 from Ciba), 2-dimethylamino-2-(4-methyl-benzyl)-l-(4- morpholin-4-yl-phenyl)-butan-l-one (Irgacure 379 from Ciba), 4-benzoyl-4'-methyl diphenyl sulphide (Chivacure BMS from Chitec), 4,4'- bis(diethyIamino)

benzophenone (Chivacure EMK from Chitec), and 4,4'-bis(N,N^,-dimethylamino) benzophenone (Michler's ketone). Also suitable are mixtures thereof.

[0059] Additionally, photosensitizers are useful in conjunction with

photoinitiators in effecting cure with light sources in this wavelength range.

Examples of suitable photosensitizers include: anthraquinones, such as 2- methylanthraquinone, 2-ethylanthraquinone, 2-tertbutylanthraquinone, 1 - chloroanthraquinone, and 2-amylanthraquinone, thioxanthones and xanthones, such as isopropyl thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and 1-chloro- 4-propoxythioxanthone, methyl benzoyl formate (Darocur MBF from Ciba), methyl- 2-benzoyl benzoate (Chivacure OMB from Chitec), 4-benzoyl-4'-methyl diphenyl sulphide (Chivacure BMS from Chitec), 4,4'- bis(diethylamino) benzophenone (Chivacure EMK from Chitec).

[0060] When photosensitizers are employed, other photoinitiators absorbing at shorter wavelengths can be used Examples of such photoinitiators include: benzophenones, such as benzophenone, 4-methyl benzophenone, 2,4,6-trimethyl benzophenone, and dimethoxybenzophenone, and , 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone, phenyl (l-hydroxyisopropyl)ketone, 2-hydroxy- l-[4-(2-hroxyethoxy) phenyl] -2-methyl-l -propanone, and 4-isopropylphenyl(l- hydroxyisopropyl)ketone, benzil dimethyl ketal, and oligo-[2-hydroxy-2-methyl-l-[4- (1 -methyl vinyl)phenyl] propanone] (Esacure KIP 150 from Lamberti).

[0061] For light sources emitting at wavelengths from between about 100 and about 300 nm, photoinitiators absorbing at the shorter wavelengths can be used. Examples of such photoinitiators include: benzophenones, such as benzophenone, 4- methyl benzophenone, 2,4,6-trimethyl benzophenone, and dimethoxybenzophenone, and , 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone, phenyl (1 -hydroxyisopropyl)ketone, 2-hydroxy-l -[4-(2-hroxyethoxy) phenyl] -2-methyl-l- propanone, and 4-isopropylphenyl(l-hydroxyisopropyI)ketone, benzil dimethyl ketal, and oligo-[2-hydroxy-2-methyl-l-[4-(l-methylvinyl)phenyl] propanone] (Esacure KIP 150 from Lamberti).

[0062] For light sources emitting light at wavelengths from about 475 nm to about 900nm, examples of suitable photoinitiators include: camphorquinone, 4,4'- bis(diethylamino) benzophenone (Chivacure EMK from Chitec), 4,4'-bis(N,N'- dimethylamino) benzophenone (Michler's ketone), bis(2,4,6-trimethylbenzoyi)- phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), metallocenes such as bis (eta 5-2-4-cyciopentadien-l-yl) bis [2,6-difluoro-3-(lH-pyrrol-l-yl) phenyl] titanium (Irgacure 784 from Ciba), and the visible light photoinitiators from Spectra Group Limited, Inc. such as H-Nu 470, H-Nu-535, H-Nu-635, H-Nu-Blue-640, and H-Nu- Blue-660.

[0063] In one embodiment of the first aspect of the instant claimed invention, the present composition comprises, relative to the total weight of the composition, from about 0.5 wt% to about 8 wt% of one or more free radical photoinitiators. In one embodiment, the present composition comprises, relative to the total weight of the composition, from about 1 wt% to about 6 wt% of one or more free radical photoinitiators, relative to the total weight of the composition. In another

embodiment, the present composition comprises, relative to the total weight of the composition, from about 2 wt% to about 5 wt% of one or more free radical photoinitiators. [0064] Normally, cationic photoinitiators are not required or desired in urethane (meth)acrylate oligomer based radiation curable coatings to function as

photoinitiators.

[0065] The following formulation is one embodiment of the instant claimed invention with a polyester urethane acrylate oligomer.

Formula with polyester urethane acrylate

oligomer

[0066] The measurement of the amount of curing a radiation curable urethane (meth)acrylate based coating has undergone is typically done by conducting a "Percent Reacted Acrylate Unsaturation" (abbreviate "%RAU") determination. For the coatings of the instant claimed invention, upon curing with light generated using ultraviolet mercury lamps , the %RAU at the top surface of the coating is about 60% or greater, preferably about 70% or greater, more preferably about 75% or greater, more highly preferably about 80% or greater, most preferably about 85% or greater, most highly preferably about 90% or greater, and highest preferably about 95% or greater. It is possible to achieve a %RAU of 100% using light generated using ultraviolet mercury lamps to cure the compositions of the instant claimed invention.

The radiation curable coatings of the instant claimed invention have a liquid viscosity between about 100 mPa-s and about 2500 mPa s; and a cured film of the radiation curable coating has

a Modulus of between about 100 MPa and about 650 MPa;

an Elongation at break of between about 10% and about 30%;

a Pencil Hardness of between about B and F;

a Water Adhesion of at least about 95%;

a Water Resistance (APR) of about 0;

a Hydrocarbon T3 Resistance (APR) of between about -2 to about -4; and a Skydrol LD4 resistance (APR) of between about -4 to about -1. In an embodiment the liquid viscosity is at least about 100 mPa-s.

In an embodiment the liquid viscosity is at least about 150 mPa-s.

In an embodiment the liquid viscosity is at least about 200 mPa-s.

In an embodiment the liquid viscosity is at least about 300 mPa-s.

In an embodiment the liquid viscosity is at least about 325 mPa-s.

In an embodiment the liquid viscosity is at least about 350 mPa-s.

In an embodiment the liquid viscosity is no more than about 2500 mPa-s. In an embodiment the liquid viscosity is no more than about 2400 mPa-s. In an embodiment the liquid viscosity is no more than about 2300 mPa-s. In an embodiment the liquid viscosity is no more than about 2200 mPa-s. In an embodiment the liquid viscosity is no more than about 2100 mPa-s. In an embodiment the liquid viscosity is no more than about 2000 mPa-s.

[0067] With careful selection of the ingredients chosen to synthesize the oligomer and the coating made with the oligomer it is possible to synthesize radiation curable coatings for aerospace applications wherein at least about 15% of the ingredients in the coating are bio-based, rather than petroleum based.

[0068] In an embodiment, the radiation curable aircraft coating composition of the instant claimed invention is such that at least about 15% of the ingredients in the coating are bio-based, rather than petroleum based.

[0069] In an embodiment, the radiation curable aircraft coating composition of the instant claimed invention is such that at least about 20% of the ingredients in the coating are bio-based, rather than petroleum based.

[0070] In an embodiment, the radiation curable aircraft coating composition of the instant claimed invention is such that at least about 25% of the ingredients in the coating are bio-based, rather than petroleum based. [0071] The fourteenth aspect of the instant claimed invention is a radiation curable coating composition for the exterior surfaces of an aircraft comprising:

at least one urethane (meth) acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light emitted from a light emitting diode (LED) having a wavelength from about 100 nm to about 900nm, to provide a cured coating on the exterior surfaces of the aircraft, said cured coating having a top surface, said cured coating having a % Reacted Acrylate Unsaturation (%RAU) of about 60% or greater.

[0072] Urethane (meth)acrylate oligomers and reactive diluent monomers are as previously described in this patent application.

[0073] To successfully formulate a radiation curable coating for aircraft, it is necessary to review the photoinitiator(s) present in the coating to determine if they will be activated by the LED light chosen to provide the curing light.

[0074] For LED light sources emitting in the 300 - 475nm wavelength range- especially those emitting at 365nm, 390nm, or 395nm, examples of suitable photoinitiators absorbing in this area include: benzoyiphosphine oxides, such as, for example, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (Lucirin TPO from BASF) and 2,4,6-trimethylbenzoyl phenyl, ethoxy phosphine oxide (Lucirin TPO-L from BASF), bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropanone-l (Irgacure 907 from Ciba), 2-benzyl-2-(dimethylamino)-l-[4-(4-morphoIinyl) phenyl]-l- butanone (Irgacure 369 from Ciba), 2-dimethylamino-2-(4-methyl-benzyl)-l-(4- morpholin-4-yl-phenyi)-butan-l-one (Irgacure 379 from Ciba), 4-benzoyl-4'-methyl diphenyl sulphide (Chivacure BMS from Chitec), 4,4'- bis(diethylamino)

benzophenone (Chivacure EMK from Chitec), and 4,4'-bis(N,N'-dimethylammo) benzophenone (Michler's ketone). Also suitable are mixtures thereof.

[0075] Additionally, photosensitizers are useful in conjunction with

photoinitiators in effecting cure with LED light sources emitting in this wavelength range. Examples of suitable photosensitizers include: anthraquinones, such as 2- methylanthraquinone 2-ethylanthraquinone 2-tertbutylanthraquinone 1- chloroanthraquinone, and 2-amylanthraquinone, thioxanthones and xanthones, such as isopropyl thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and 1-chloro- 4-propoxythioxanthone, methyl benzoyl formate (Darocur MBF from Ciba), methyl- 2-benzoyl benzoate (Chivacure OMB from Chitec), 4-benzoyl-4'-methyl diphenyl sulphide (Chivacure BMS from Chitec), 4,4'- bis(diethylamino) benzophenone (Chivacure EMK from Chitec).

[0076] When photosensitizers are employed, other photoinitiators absorbing at shorter wavelengths can be used. Examples of such photoinitiators include:

benzophenones, such as benzophenone, 4-methyl benzophenone, 2,4,6-trimethyl benzophenone, and dimethoxybenzophenone, and , 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl phenyl ketone, phenyl (l-hydroxyisopropyl)ketone, 2-hydroxy- l-[4-(2-hroxyethoxy) phenyl]-2-methyl-1 -propanone, and 4-isopropylphenyl(l- hydroxyisopropyl)ketone, benzil dimethyl ketal, and oligo-[2-hydroxy-2-methyl-l-[4- (1 -methylvinyl)phenyl] propanone] (Esacure KIP 150 from Lamberti).

[0077] The trend is for LED UV light sources to be designed to emit light at shorter wavelengths. For LED light sources emitting at wavelengths from between about 100 and about 300 nm, photoinitiators absorbing at the shorter wavelengths can be used. Examples of such photoinitiators include: benzophenones, such as benzophenone, 4-methyl benzophenone, 2,4,6-trimethyl benzophenone, and dimethoxybenzophenone, and , 1-hydroxyphenyl ketones, such as 1- hydroxycyclohexyl phenyl ketone, phenyl (l-hydroxyisopropyl)ketone, 2-hydroxy-l- [4-(2-hroxyethoxy) phenyl]-2 -methyl- 1 -propanone, and 4-isopropylphenyl(l- hydroxyisopropyl)ketone, benzil dimethyl ketal, and oligo-[2-hydroxy-2-methyl-l-[4- (l-methylvinyl)phenyl] propanone] (Esacure KIP 150 from Lamberti).

[0078] LED light sources can also be designed to emit visible light, which can also be used to cure radiation curable coatings for aircraft. For LED light sources emitting light at wavelengths from about 475 nm to about 900nm, examples of suitable photoinitiators include: camphorquinone, 4,4'- bis(diethylamino)

benzophenone (Chivacure EMK from Chitec), 4,4'-bis(N,N'-dimethylamino) benzophenone (Michler's ketone), bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819 or BAPO from Ciba), metallocenes such as bis (eta 5-2-4- cyclopentadien-l-yl) bis [2,6-difluoro-3-(IH-pyrroI-l-yl) phenyl] titanium (Irgacure 784 from Ciba), and the visible light photoinitiators from Spectra Group Limited, Inc. such as H-Nu 470 H-Nu-535 H-Nu-635 H-Nu-Blue-640 and H-Nu-Blue-660. [0079] In one embodiment of the instant claimed invention, the light emitted by the LED is UVA radiation, which is radiation with a wavelength between about 320 and about 400nm.

[0080] In one embodiment of the instant claimed invention, the light emitted by the LED is UVB radiation, which is radiation with a wavelength between about 280 and about 320nm.

[0081] In one embodiment of the instant claimed invention, the light emitted by the LED is UVC radiation, which is radiation with a wavelength between about 100 and about 280nm.

[0082] In one embodiment of the instant claimed invention, the present composition comprises, relative to the total weight of the composition, from about 0.5 wt% to about 7 wt% of one or more free radical photoinitiators. In one embodiment, the present composition comprises, relative to the total weight of the composition, from about 1 wt% to about 6 wt% of one or more free radical photoinitiators, relative to the total weight of the composition. In another embodiment, the present composition comprises, relative to the total weight of the composition, from about 2 wt% to about 5 wt% of one or more free radical photoinitiators.

[0083] Normally, cationic photoinitiators are not required or desired in urethane (meth)acrylate oligomer based radiation curable coatings to function as

photoinitiators.

[0084] The measurement of the amount of curing a radiation curable urethane (meth)acrylate based coating has undergone is typically done by conducting a "Percent Reacted Acrylate Unsaturation" (abbreviate "%RAU") determination. For the coatings of the instant claimed invention, upon curing with an LED light having a wavelength of from about 100 nm to about 900nm, the %RAU at the top surface of the coating is about 60% or greater, preferably about 70% or greater, more preferably about 75% or greater, more highly preferably about 80% or greater, most preferably about 85% or greater, most highly preferably about 90% or greater, and highest preferably about 95% or greater. It is possible to achieve a %RAU of 100% using LED's to cure the compositions of the instant claimed invention.

[0085] The fifthteenth aspect of the instant claimed invention is a coated aircraft comprising an aircraft and at least one coating, wherein said at least one coating is produced by coating the exterior surface of said aircraft with at least one coating composition comprising: at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface, and curing said uncured coated exterior surface of an aircraft by irradiating with light emitted from a light emitting diode (LED) having a wavelength from about 100 nm to about 900nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of about 60% or greater.

[0086] The sixteenth aspect of the instant claimed invention is a process for coating an aircraft comprising:

providing an aircraft, said aircraft possessing exterior surfaces in need of being coated;

coating said exterior surfaces of said aircraft with at least one coating composition, wherein said at least one coating composition comprises:

at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface of an aircraft, and

curing said uncured coated exterior surface of an aircraft by irradiating with light emitted from a light emitting diode (LED) having a wavelength from about 100 nm to about 900nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of about 60% or greater.

[0087] The change of E' (storage modulus) from glass state to rubbery state is gradual (slope of downward facing transition is much less "vertical" than with other radiation curable coatings. This gradual slope allows for the coating to exhibit the desired flexibility from low (-60 °C to -80°C) temperatures to high (>60 °C) temperatures. It is believed, without intending to be bound thereby, that this desired flexibility is critical for the operation of aircraft that must function well in all sorts of temperatures.

[0088] The specific examples herein disclosed are to be considered as being primarily illustrative. Various changes beyond those described, will, no doubt, occur to those skilled in the art; and such changes are to be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.

EXAMPLES

[0089] The present invention is further illustrated with a number of examples, which should not be regarded as limiting the scope of the present invention. The components listed in these Examples have the following commercial names, are available from the listed source and have the indicated chemical composition.

Test Methods:

[0090] Viscosity measurements are run on the Physica MC-10 viscometer 4 at 25°C using the Z3 system and a shear rate of 50 sec^-1.

[0091] Coatings for mechanical property testing are applied on glass supported Mylar using a Headway Research Spinner, 3-mil Bird bar.

[0092] Films for mechanical property testing are cured using Fusion Systems 300 W/in D lamp at 1.0 J/cm², in air, with the lamp raised out of focus resulting in a measured irradiance of about 700 mW-cm^-2 unless otherwise noted.

[0093] Coatings for panel testing are applied onto topcoated and activated aluminum panels using a HVLP air spraygun. The coatings are applied at room temperature or the coatings can be preheated to 60°C to facilitate spray application depending upon viscosity of the coating.

[0094] Coated panels are cured as above.

TEST METHODS

A.1 Tensile Strength, Elongation, and Modulus Test Method for Cured Film

Samples using the Instron

[0095] The tensile properties (tensile strength, percent elongation at break, and modulus) of cured samples are determined using an Instron model 4201 universal testing instrument. Samples are prepared for testing by curing a 75-μιη film of the material using a Fusion UV processor. Samples are cured at 1.0 J/cm in a nitrogen atmosphere. Test specimens having a width of 0.5 inches and a length of 5 inches are cut from the film. The exact thickness of each specimen is measured with a micrometer.

For soft coatings (e.g., those with a modulus of less than about 10 MPa), the coating is drawn down and cured on a glass plate and the individual specimens cut from the glass plate with a scalpel. A 2-lb load cell is used in the Instron and modulus is calculated at 2.5% elongation with a least squares fit of the stress-strain plot. Cured films are conditioned at 23 ± 1°C and 50 ± 5% relative humidity for a minimum of one hour prior to testing.

[0096] For harder coatings, the coating is drawn down on a Mylar film and specimens are cut with a Thwing Albert 0.5-inch precision sample cutter. A 20-lb load cell is used in the Instron and modulus is calculated at 2.5% elongation from the secant at that point. Cured films are conditioned at 23 ± 1 °C and 50 ± 5% relative humidity for sixteen hours prior to testing.

For testing specimens, the gage length is 2-inches and the crosshead speed is 1.00 inches/minute. All testing is done at a temperature of 23 ± 1°C and a relative humidity of 50 ± 5%. All measurements are determined from the average of at least 6 test specimens.

A.2. DMA Test Method for Cured Film Samples: E', E". tan delta and

Equilibrium Modulus Eo [0097] Dynamic Mechanical Analysis (DMA) is carried out on the test samples, using an RS A-II or RSA-3 instrument manufactured by TA Instruments, A free film specimen (typically about 36 mm long, 12 mm wide, and 0.075 mm thick) is mounted in the grips of the instrument, and the temperature initially brought to 80°C and held there for about five minutes. During the latter soak period at 80°C, the sample is stretched by about 2.5% of its original length. Also during this time, information about the sample identity, its dimensions, and the specific test method is entered into the software (RSI Orchestrator) residing on the attached personal computer.

[0098] All tests are performed at a frequency of 1 ,0 radians, with the dynamic temperature step method having 2°C steps, a soak time of 5 to 10 seconds, an initial strain of about 0.001 (ΔL/L), and with autotension and autostrain options activated. The autotension is set to ensure that the sample remained under a tensile force throughout the run, and autostrain is set to allow the strain to be increased as the sample passed through the glass transition and became softer. After the 5 minute soak time, the temperature in the sample oven is reduced in 20°C steps until the starting temperature, typically -80°C or -60°C, is reached. The final temperature of the run is entered into the software before starting the run, such that the data for a sample would extend from the glassy region through the transition region and well into the rubbery region.

[0099] The run is started and allowed to proceed to completion. After completion of the run, a graph of E', E", and tan delta, all versus temperature, appeared on the computer screen. The data points on each curve are smoothed, using a program in the software. On this plot, three points representing the glass transition are identified: 1) The temperature at which E' = 1000 MPa; 2) The temperature at which E' = 100 MPa; 3) The temperature of the peak in the tan delta curve. If the tan delta curve contained more than one peak, the temperature of each peak is measured. One additional value obtained from the graph is the minimum value for E' in the rubbery region. This value is reported as the equilibrium modulus, E₀.

Viscosity

[00100] The viscosity is measured using a Physica MCIO Viscometer. The test samples are examined and if an excessive amount of bubbles is present, steps are taken to remove most of the bubbles. Not all bubbles need to be removed at this stage, because the act of sample loading introduces some bubbles. [00101] The instrument is set up for the conventional Z3 system, which is used. The samples are loaded into a disposable aluminum cup by using the syringe to measure out 17 cc. The sample in the cup is examined and if it contains an excessive amount of bubbles, they are removed by a direct means such as centrifugation, or enough time is allowed to elapse to let the bubbles escape from the bulk of the liquid. Bubbles at the top surface of the liquid are acceptable.

[00102] The bob is gently lowered into the liquid in the measuring cup, and the cup and bob are installed in the instrument. The sample temperature is allowed to equilibrate with the temperature of the circulating liquid by waiting five minutes. Then, the rotational speed is set to a desired value which will produce the desired shear rate. The desired value of the shear rate is easily determined by one of ordinary skill in the art from an expected viscosity range of the sample.

[00103] The instrument panel read out a viscosity value, and if the viscosity value varied only slightly (less than 2% relative variation) for 15 seconds, the measurement is complete. If not, it is possible that the temperature had not yet reached an equilibrium value, or that the material is changing due to shearing. If the latter case, further testing at different shear rates will be needed to define the sample's viscous properties. The results reported are the average viscosity values of three test samples.

[00104] Coatings for panel testing are applied onto topcoated and activated aluminum panels using a HVLP air spraygun.

[00105] The coatings are preheated to 60°C to facilitate spray application. Coated panels are cured as above.

[00106] Cross-hatch adhesion is tested according to the "Cross-Cut Method" as described in the following paragraphs:

[00107] The "Cross-Cut" adhesion method describes a procedure for assessing the adhesion of coating films to a substrate or to another coating by removing a pressure sensitive tape from a lattice pattern of perpendicular cuts through the coating. This test is not suitable for coatings with total thickness greater than 250 μm.

[00108] To begin with a cured film is made using standard curing techniques. After the film is cured, but before beginning this test blow off any dust particles from the surface of the film coating. Select an area free of blemishes or minor surface imperfections. Place the sample on a firm, flat, horizontal surface and make parallel cute. Space the cuts approximately 1 mm apart and make six parallel cuts. Make all cuts approximately 20 mm long. Cut through the film in one steady motion using just enough pressure to cut through the coating. When making successive single cuts with the aid of a guide, place the guide on the uncut area. For multi-coat systems, a sharp razor blade or scalpel should be used; apply just enough pressure to score the top layer. After making the necessary cuts, brush the film lightly with a soft brush.

[00109] Make the same number of cuts at 90° to the original cuts.

Remove a length of tape from the roll and discard. Then remove about 75 mm of tape at a steady rate. Cut the tape. Place the center of the tape over the grid and smooth in place by a finger. Rub the tape firmly with the eraser on the end of the pencil to ensure good contact. After 90 sec, remove the tape by pulling on the free end rapidly back at an angle as close to 180° as possible.

[00110] Examine the grid area for removal of coating in good lighting. Rotate the panel so that viewing and lighting are not confined to one direction. It is also useful to examine the tape for removed coating. Rate the adhesion in accordance with the following scale. See Table gamma.

5B The edges of the cuts are completely smooth; none of the squares of the lattice is detached - 100% adhesion

4B Small flakes of the coating are detached at intersections; less than 5% of the area is affected - > 95% adhesion

3B Small flakes of the coating are detached along edges and intersections of cuts; area affected is 5 to 15% of the lattice - 85 - 95% adhesion

2B The coating has flaked along the edges and on parts of the squares; area affected is 15 to 35% of the lattice - 65 - 85% adhesion

1B The coating has flaked along the edges of cuts in large ribbons and whole squares have detached; area affected is 35 to 65% of the lattice - 35 - 65% adhesion

OB Flaking and detachment worse than 1 - No adhesion

[00111] Repeat the cutting and taping steps on two other locations on the sample, making sure that the distance from each other and from the edge of the sample is not less than 5 mm. In reporting the results --report the scale where failure occurred. Results should be considered suspect if they differ by more than one scale unit. Results can be reported either by classification or percent adhesion. See Table Gamma

[00112] Pencil hardness is measured according to ASTM D3363, © 2005, using the mechanical pencils and no sled.

Reverse impact is tested using ASTM D6905, © 2003, Reapproved 2008, and the Mandrel bend test is according to ASTM D522B, © 1993, Reapproved 2008. Fluid resistance is determined by room temperature immersion of a coated panel in the appropriate fluid for the required time period followed by immediate determination of the pencil hardness rating.

Resistance is measured by the change in the pencil hardness rating compared to the original rating.

The Film Appearance Test method is a visual examination of the surface appearance of the cured film.

[00113] The following LED lamp with the indicated settings is used for aerospace coating testing.

Model: Phoseon 75x50WC 395, RX FireFlex, water cooling LED, S/N: 585001 Speed: 27 ft/min

LED output:

By EIT Power Puck, S/N: 2692. UVB =UVC=0. UVA-0.499 w/cm² and 0.136 J/ cm².

The measurement for UW is saturation with current Power Puck.

UVV > 5.000 w/ cm² and > 01,584 J/ cm².

Example Two- Formulation Including Oligomer A

[00114] The indicated Oligomer is first synthesized separately and then the indicated formulations are made using that Oligomer.

Oligomer A

Example 5 Formulation Including Oligomer B

Oligomer B

[00115] The indicated Oligomer is first synthesized separately and then the indicated formulations are made using that Oligomer.

The following LED description is used for aerospace coating testing.

Model: Phoseon 75x50WC 395, RX FireFlex, water cooling LED, S/N: 585001 Speed: 27 ft/min

LED output:

By EIT Power Puck,

S/N: 2692. UVB =UVC=0. UVA-0.499 w/cm² and 0.136 J/ cm²

The measurement for UVV is saturation with current Power Puck.

UVV > 5.000 w/ cm² and > 01.584 J/ cm².

The following LED description is used for aerospace coating testing.

Model: Phoseon 75x50WC 395, RX FireFlex, water cooling LED, S/N: 585001 Speed: 27 ft/min

LED output:

By EIT Power Puck,

S/N: 2692. UVB =UVC=0. UVA=0.499 w/cm² and 0.136 J/ cm²

The measurement for UVV is saturation with current Power Puck.

UVV > 5 000 w/ cm² and > 01.584 J/ cm².

Example Ten - Formulation Including Oligomer E

[00116] The indicated Oligomer is first synthesized separately and then the indicated formulations are made using that Oligomer.

Example 10 Part 1, Oligomer E Synthesis

Example Twelve-Examples using Oligomer F and Oligomer G

[00117] The indicated Oligomer is first synthesized separately and then the indicated formulations are made using that Oligomer.

Oligomer F Formulation:

63

[00118] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference are individually and specifically indicated to be incorporated by reference and are set forth in its entirety herein.

[00119] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising,"

"having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it are individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[00120] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[00121] While the invention has been described in detail and with reference to specific embodiments thereof it will be apparent to one of ordinary skill in the art that various changes and modifications can be made therein without departing from the spirit and scope of the claimed invention.

[00122] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one of ordinary skill in the art that various changes and modifications can be made therein without departing from the spirit and scope of the claimed invention.

Claims

1. A radiation curable coating composition for the exterior surfaces of an aircraft, wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode (LED) having a wavelength from 100 nm to 900 nm, to provide a cured coating on the exterior surfaces of the aircraft, said cured coating having a top surface, said cured coating having a % Reacted Acrylate Unsaturation (%RAU) of 60 % or greater.

2. The radiation curable aircraft coating composition of claim 1, wherein the light emitting diode (LED) has a wavelength of

from 100 nm to 300 nm;

from 300 nm to 475 nm; or

from 475 nm to 900 nm.

3. A radiation curable coating composition for the exterior surfaces of an aircraft, wherein the composition is capable of undergoing photopolymerization when coated on an exterior surface of an aircraft and when cured by irradiating with light generated using ultraviolet mercury lamps,

wherein the radiation curable coatings have a liquid viscosity between 100 mPa-s and 2500 mPa-s; and

a cured film of the radiation curable coating has

a tensile Modulus or equilibrium Modulus of between 100 MPa and 650 MPa; an Elongation at break of between 10 % and 30 %;

a Pencil Hardness (PR) of between B and F;

a Water Adhesion of at least 95 %;

a Water Resistance (APR) of from 0 to -2;

a Hydrocarbon T3 Resistance (APR) of between -2 to -4; and

a Skydrol LD4 resistance (APR) of between -4 to -1.

4. A radiation curable coating composition according to any one of claims 1-3, said composition comprising:

at least one urethane (meth) acrylate oligomer;

at least one reactive diluent monomer; and at least one photoinitiator.

5. The radiation curable coating composition of claim 4, wherein the photoinitiator is a Type I photoinitiator.

6. The radiation curable coating composition of claim 4, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

7. The radiation curable coating composition of any one of claims 1-6, in which at least 15 % of the ingredients in the coating are bio-based, rather than petroleum based, preferably at least 20 % of the ingredients, more preferably at least 25 % of the ingredients.

8. A process for coating an aircraft comprising:

providing an aircraft, said aircraft possessing exterior surfaces in need of being coated;

coating said exterior surfaces of said aircraft with at least one coating composition, preferably a radiation curable coating composition according to any one of claims 1-7, and wherein said at least one coating composition comprises:

at least one urethane (meth)acrylate oligomer;

at least one reactive diluent monomer; and

at least one photoinitiator;

to obtain an uncured coated exterior surface of an aircraft, and

curing said uncured coated exterior surface of an aircraft by irradiating with light emitted either from an ultraviolet mercury lamp or from a light emitting diode(LED) having a wavelength from 100 nm to 900 nm, to obtain a cured coating having a top surface, wherein the cured coating has a % Reacted Acrylate Unsaturation (% RAU) of 60 % or greater.

9. The process of claim 8, wherein the light emitting diode (LED) has a wavelength of

from 100 nm to 300 nm; from 300 ran to 475 nm; or

from 475 nm to 900 nm.

10. The process of claim 8 or 9, wherein the photoinitiator is a Type I photoinitiator.

11. The process of claim 8 or 9, wherein the photoinitiator is a Type II photoinitiator and the composition includes a hydrogen donor.

12. A coated aircraft obtainable by the process of any one of claims 8-11.