A post repair coating composition

Abstract

A post repair coating composition for a food or beverage package, such as a food or beverage can, the coating composition comprising: a) an acrylic material comprising acid-functionality, wherein the acrylic material having has an acid value below 50 mg KOH / g; and b) a crosslinker material, the crosslinker material being formed from reactants that are substantially free of formaldehyde.

Description

A Post Repair Coating CompositionField of the Invention

[0001] The present invention relates to a post repair coating composition, in particular to a post repair coating comprising an acrylic material comprising acid-functionality, wherein the acrylic material has an acid value below 50 mg KOH / g, and a crosslinker material, wherein the crosslinker material is formed from reactants that are substantially free of formaldehyde. The present invention further relates to a food or beverage can comprising a surface having a coating on at least a portion thereof, the coating being derived from the post repair coating composition. The present invention further relates to a method of repairing a score line on a food or beverage can, the method comprising applying to the score line the post repair coating composition.Background of the Invention

[0002] Metal containers are being equipped more and more with so-called easy open ends (EOEs) in which a user accesses the interior of the container by piercing the container in a predetermined manner, without the need for a separate opening device. Such easy open ends are routinely used in food and beverage cans.

[0003] The principle of easy opening is obtained by reducing the thickness of the metal to thereby provide a score line which is weaker and susceptible to opening. During the scoring operation, which is often achieved by stamping with a punch, any external varnish layers present on the surface are cut and therefore the corrosion resistance of the metal substrate is compromised. This is particularly problematic in a context where: i) the metal has been stressed and therefore its resistance to corrosion is weakened; ii) the tin layer of the tinplate (where this is the substrate) is also cut; ill) the next treatment step of the packaging is sterilisation, where the presence of heat and high humidity will create high corrosion conditions; and / or iv) the container is at the beginning of its life cycle which has a minimum of two years.

[0004] The corrosion resistance of the metal substrate may be restored by the application of a repair coating to the score line. This coating is often applied by spraying and in particular by an airless spray process.

[0005] Current repair formulations are generally based on a crosslinkable resin, such as an epoxy resin or acrylic resin. These compositions are characterised by high volatile organic compounds (VOC), a low cross-linkage speed and a limited pot life (from a few hours to a week), as well as high levels of side product being produced.

[0006] It is desired to provide coatings with reduced levels of volatile organic content (VOC) when compared to the current compositions.

[0007] In addition, epoxy-based coatings are prepared from monomers such as bisphenol A and bisphenol A diglycidyl ether (“BADGE”). BPA is perceived as being harmful to human health andit is therefore desirable to eliminate it from coatings. Derivatives of BPA such as diglycidyl ethers of bisphenol A (BADGE), epoxy novolak resins and polyols prepared from BPA and bisphenol F (BPF) are also perceived to be problematic. Government authorities, particularly in Europe, are becoming even more restrictive on the amount of free BADGE or its by-products that are acceptable.

[0008] It is an object of embodiments of the present invention to provide a solution to one or more of the above mentioned or other problems.Summary of the Invention

[0009] According to a first aspect of the present invention there is provided a post repair coating composition for a food or beverage package, the coating composition comprising: a) an acrylic material comprising acid-functionality, wherein the acrylic material has an acid value below 50 mg KOH / g; and b) a crosslinker material, wherein the crosslinker material is formed from reactants that are substantially free of formaldehyde.

[0010] The food or beverage package may be a food or beverage can. Thus, the post repair coating composition may be for a food or beverage can.

[0011] There is also provided a food or beverage package, such as a food or beverage can, comprising a surface having a coating on at least a portion thereof, the coating being derived from a post repair coating composition comprising: a) an acrylic material comprising acid-functionality, wherein the acrylic material has an acid value below 50 mg KOH / g; and b) a crosslinker material, wherein the crosslinker material is formed from reactants that are substantially free of formaldehyde.

[0012] There is also provided a method of repairing a score line on a food or beverage package, such as a food or beverage can, the method comprising applying to the score line a post repair coating composition comprising: a) an acrylic material comprising acid-functionality, wherein the acrylic material has an acid value below 50 mg KOH / g; and b) a crosslinker material, wherein the crosslinker material is formed from reactants that are substantially free of formaldehyde.

[0013] The post repair coating composition may comprise a liquid carrier. The liquid carrier may comprise water.

[0014] The post repair coating composition may be a two-component system, wherein the two- component system comprises a first component comprising the acrylic material (a) and a second component comprising the crosslinker material (b).Detailed Description of the Invention

[0015] The post repair coating composition of the present invention comprises an acrylic material comprising acid-functionality. The post repair coating composition may comprise any suitable acrylic material. The acrylic material may typically be formed from a reaction mixture, the reaction mixture may comprise one or more acrylic monomer(s), for example selected from alkyl (alk)acrylate, alkyl (meth)acrylate, and / or (alk)acrylic acid.

[0016] The acrylic material comprises acid-functionality. By this, it is meant that the acrylic material comprises pendant acid groups, such as pendant carboxylic acid groups, for example. This may be achieved, by way of example, by including an acid functional acrylic monomer, such as acrylic acid or methacrylic acid, for example, in the preparation of the acrylic material.

[0017] Suitable acrylic monomers will be well known to a person skilled in the art. The acrylic material may be formed from more than one acrylic monomer. Suitable acrylic monomers include, but are not limited to, alkyl (alk)acrylate, such as Ci to Ge alkyl (Ci to Ge alk)acrylate, for example, Ci to Co alkyl (meth)acrylate, and (alk)acrylic acid, such as (Ci to Ge alk)acrylic acid.

[0018] As used herein, “(alk)acrylate”, "(meth)acrylate" and like terms are used conventionally and herein to refer to both alkacrylate and acrylate, such as methacrylate and acrylate.

[0019] Examples of suitable acrylic monomers include, but are not limited to, acrylic acid, methacrylic acid, methyl acrylate; methyl methacrylate; ethyl acrylate; ethyl methacrylate; propyl acrylate; propyl methacrylate; isopropyl methacrylate, butyl acrylate, including n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate and tert-butyl acrylate; butyl methacrylate, including n-butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate and tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, decyl acrylate, decyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, octyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, isobornyl acrylate, isobornyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, phenoxy ethyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate; the reaction product of (meth)acrylic acid reacted with an epoxy, such as the reaction product of (meth)acrylic acid reacted with Cardura (RTM) E10P glycidyl ester; ethylene glycol diacrylate; ethylene glycol dimethacrylate; 1 ,6-hexanediol diacrylate; 1 ,6-hexanediol dimethacrylate; 4-hydroxybutyl acrylate; 4-hydroxybutyl methacrylate; allyl methacrylate; benzyl acrylate; benzyl methacrylate; phosphate esters of 2-hydroxyethyl methacrylate; those sold under the trade name SIPOMER commercially available from Solvay) such as, for example SIPOMER PAM-100, SIPOMER PAM-200 and SIPOMER PAM-300 (phosphate esters of polypropylene glycol monoacrylate); and SIPOMER WAM, SIMPOMER WAM II and SIPOMER WAM E W50 (methacrylic monomer based on 46-50% methacrylamidoethyl ethylene urea), ureido (meth)acrylate (commercially available from BASF), rosin (meth)acrylate, cardanyl (meth)acrylate, cardanol (meth)acrylate, acrylamides such as, for example, acrylamide methacrylamide, N,N-dimethylacrylamide, N-ethylacrylamide, N-hydroxyethyl acrylamide,diacetone acrylamide, N,N-diethylacrylamide, N-isopropylacrylamide and N- isopropylmethacrylamide; 2-acrylamido-2-methyl-1 -propanesulfonic acid; silane-functional (alk)acrylic acids and / or (alk)acrylates such as, for example, 3-(trimethoxysilyl)propyl methacrylate (also known as silane A174, commercially available from Sigma Aldrich) and 3- (trimethoxysilyl)propyl acrylate (commercially available from Sigma Aldrich); and combinations thereof. Any other acrylic monomers known to those skilled in the art could also be used.

[0020] At least one of the acrylic monomers may comprise a functional group, such as a hydroxy group. The acrylic monomer may comprise a hydroxyl functional acrylic monomer. The acrylic monomer may comprise a hydroxyl functional alkyl(alk)acrylate, for example, hydroxyl functional Ci to Cs alkyl (Ci to Cs alk)acrylate, such as hydroxyl functional Ci to Cs alkyl (meth)acrylate or hydroxyl functional Ci to Ce alkyl (Ci to Ce alk)acrylate. Examples of suitable hydroxyl functional acrylic monomer(s) include, but are not limited to, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxymethyl acrylate, hydroxymethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypentyl acrylate, hydroxypentyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, methyl 2-(hydroxymethyl)acrylate ethyl 2-(hydroxymethyl)acrylate, polyethylene glycol methacrylate and / or polypropylene glycol methacrylate. The hydroxyl functional acrylic monomer may comprise hydroxyethyl acrylate, hydroxyethyl methacrylate, the reaction product of (meth)acrylic acid reacted with an epoxy, such as the reaction product of (meth)acrylic acid with Cardura (RTM) E10P glycidyl ester, polyethylene glycol methacrylate and / or polypropylene glycol methacrylate.

[0021] At least one acrylic monomer may comprise two or more ethylenically unsaturated groups, i.e., may be a multi-ethylenically unsaturated monomer. Examples of suitable multi- ethylenically unsaturated monomers include, but are not limited to, multi-ethylenically unsaturated (alk)acrylates, such as multi-ethylenically unsaturated (meth)acrylates, alkenyl (alk)acrylates, alkynyl (alk)acrylates, and combinations thereof. Examples of suitable multi- ethylenically unsaturated (alk)acrylates include, for example, polyhydric alcohol esters of acrylic acid or methacrylic acid. For example, the acrylic monomer may comprise two, three, four or more acrylate groups. For the avoidance of doubt, by “acrylate group”, and like terms as used herein, is meant salts and esters of acrylic acid, i.e. monomers having the structure R- C=CCOO-R1, wherein R represents hydrogen, alkyl, alkenyl alkynyl, aralkyl or aryl and R1represents hydrogen, alkyl, alkenyl alkynyl, aralkyl or aryl. The acrylic monomer may comprise a di(alk)acrylate. Suitable di(alk)acrylates will be known to a person skilled in the art. Examples of suitable di(alk)acrylates include, but are not limited to, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1 ,2-propanediol diacrylate, 1 ,3-propanediol diacrylate, 1 ,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,2-petanediol diacrylate, 1 ,3-petanediol diacrylate, 1 ,5-petanediol diacrylate, 1 ,2-hexanediol diacrylate, 1 ,3-hexanediol diacrylate, 1 ,4-hexanediol diacrylate, 1,6- hexanediol diacrylate, 1 ,2-propanediol dimethacrylate, 1 ,3-propanediol dimethacrylate, 1,3- butanediol dimethacrylate, 1 ,4-butanediol dimethacrylate, 1 ,2-petanediol dimethacrylate, 1,3-petanediol dimethacrylate, 1 ,5-petanediol dimethacrylate, 1 ,2-hexanediol dimethacrylate, 1,3- hexanediol dimethacrylate, 1 ,4-hexanediol dimethacrylate, 1,6-hexanediol dimethacrylate and combinations thereof. The acrylic monomer may comprise a tri(alk)acrylate. Suitable tri(alk)acrylates will be known to a person skilled in the art. Examples of suitable tri(alk)acrylates include, but are not limited to, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and combinations thereof.

[0022] Examples of suitable alkenyl (alk)acrylates include, for example, allyl acrylate, allyl methacrylate, and combinations thereof.

[0023] The reaction mixture from which the acrylic material is formed may further comprise one or more additional ethylenically unsaturated monomer(s). Suitable additional ethylenically unsaturated monomers will be known to a person skilled in the art. Examples of suitable additional ethylenically unsaturated monomers include, but are not limited to, aryl substituted ethylenically unsaturated monomers such as, for example, styrene, alpha-methyl styrene, 3,4- alpha-methyl styrene, 2-methyl styrene, 4-methyl styrene (vinyl toluene), 2,3-dimethyl styrene, 2-ethyl styrene, 4-tertbutylstyrene, 4-methoxystyrene, 4-phenylstyrene, 4-phenoxy styrene, 4- propyl styrene, 4-benzylstyrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 4-(phenyl butyl)styrene, 2-methyl-4-isopopyl styrene, 2-ethyl-4-benzyl styrene, 4-chlorostyrene, 2,5- dichlorostyrene, 3,4-dichlorostyrene, 2,6-dichlorostyrene, 4-fluorostyrene, divinylbenzene, isopropyl styrene, t-butyl styrene, trans-beta-styrene, chloromethylstyrene, 4-hydroxystyrene, diglycidyloxymethylstyrene, 2,4-diglycidyloxymethylstyrene, 2,5-diglycidyloxymethylstyrene, 2,6- diglycidyloxymethylstyrene, 2,3,4-triglycidyloxymethylstyrene, 2,3,5-triglycidyl oxime styrene, 2,3,6-triglycidyloxymethylstyrene and 3,4,5-triglycidyloxymethylstyrene, 2,4,6- triglycidyloxymethylstyrene, unsaturated carboxylic acids or diacids (or anhydrides) such as, for examples, maleic acid (or anhydride) and itaconic acid (or anhydride), ethylenically unsaturated nitriles such as, for example, acrylonitrile or methacrylonitrile, vinyl esters such as, for example, vinyl acetate and vinyl propionate, alkenes, such as C2 to Ge alkenes, for example, ethene, propene, 1 -butene, 2-butene, 1 -pentene, 2-pentene, 1 -hexene, 2-hexene, 3-hexene, 1 -hetpene, 2-heptene, 3-heptene, 1 -octene, 2-octene, 3-octene, 4-octene and isobutylene, vinyl chloride, butadiene, isoprene, chloroprene, N-vinyl monomers such as, for example, N-vinyl pyrrolidone, N-vinyl caprolactam and N-vinyl acetamide, unsaturated fatty acid ester; allyl glycidyl ether, allyl ethyl ether, vinyl ether monomers such as, for example, methyl vinyl ether, ethyl vinyl ether, n- propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, pentyl vinyl ether, cyclopentyl vinyl ether, hexyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 1 ,4-butanediol divinyl ether, diethyleneglycol divinyl ether, triethyleneglycol divinyl ether, 1 ,4-cyclohexanedimethanol divinyl ether, 2-(2-hydroxyethyl) ethyl vinyl ether, octyl vinyl ether, benzyl vinyl ether, phenyl vinyl ether, phenethyl vinyl ether and allyl vinyl ether, vinylphosphoric acid (commercially available from Sigma Aldrich) and combinations thereof. The additional ethylenically unsaturated monomer(s)may comprise monomers, oligomers and / or polymers of the aforementioned monomers. For example, butadiene may be in the form of a monomer or may be in the form of polybutadiene.

[0024] The additional ethylenically unsaturated monomer(s) may comprise terpene monomers or derivatives thereof, rosin monomers or derivatives thereof, cardanol monomers or derivatives thereof. Examples of suitable terpene monomers or derivatives thereof include, but are not limited to, monoterpenes such as, for example, a-pinene, p-pinene, camphene, sabinene, limonene and myrcene, sesquiterpenes such as, for example, bisabolene and nerolidol, and diterpenes. Examples of suitable rosin monomers or derivates thereof include, but are not limited to, rosin, rosin acids, abietic acid, neabietic acid, palustric acid, pimaric acid, levopimaric acid, maleopimaric acid, fumaropimaric acid, isopimaric acid, rosin-formaldehyde resin, rosin alcohol and rosin phenol. Examples of suitable cardanol monomers or derivatives thereof of include, but are not limited to cardanol, anacardic acid, cardanol glycidyl ether, cardanol- formaldehyde resin, cardanol epoxies, cardanol phenols and cardanol alcohols.

[0025] The additional ethylenically unsaturated monomer may comprise a hydroxyl functional ethylenically unsaturated monomer. The hydroxyl functional ethylenically unsaturated monomer may comprise N-hydroxyethyl acrylamide, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 2-(2-hydroxyethyl) ethyl vinyl ether, and / or hydroxystyrene. The hydroxyl functional ethylenically unsaturated monomer may comprise the reaction product of (meth)acrylic acid with an epoxy (such as Cardura E10) and / or the reaction product of glycidyl methacrylate with a carboxylic acid functional component (such as a benzoic acid and / or an aliphatic acid, such as aaliphatic acid, for example).

[0026] The one or more additional ethylenically unsaturated monomer(s) may comprise two or more ethylenically unsaturated groups, i.e., may be a multi-ethylenically unsaturated monomer. Examples of suitable multi-ethylenically unsaturated monomers (that are not (alk)acrylates) include, but are not limited to, diallyl phthalate, divinylbenzene, divinyltoluene, divinylnaphthalene, and combinations thereof.

[0027] The reaction mixture from which the acrylic material is formed may be substantially free, may be essentially free or may be completely free of styrene. It will be appreciated, therefore, that the acrylic material may be substantially free, may be essentially free or may be completely free of styrene. By “substantially” free in relation to styrene, is meant that the acrylic material is formed from monomers which comprise less than 5 wt% of styrene based on the total weight of the monomers from which the acrylic material is formed. By “essentially free” in relation to styrene, is meant that the acrylic material is formed from monomers which comprise less than 1 wt% of styrene based on the total weight of the monomers from which the acrylic material is formed. By “completely free” in relation to styrene, is meant that the acrylic material is formed from monomers which comprise less than 0.01 wt% of styrene based on the total weight of the monomers from which the acrylic material is formed.

[0028] The reaction mixture from which the acrylic material is formed may comprise no, i.e. 0 wt%, styrene based on the total solid weight of the monomers. The acrylic material, therefore,may be formed from monomers which comprise no, i.e. 0 wt%, styrene based on the total weight of the monomers from which the acrylic material is formed.

[0029] The acrylic material may be completely free of styrene.

[0030] The acrylic material may comprise any suitable amount of acrylic monomer. It will be appreciated that the acrylic material comprises, i.e., is formed from a reaction mixture comprising, at least one acrylic monomer. It will be appreciated that the acrylic material comprises, i.e., is formed from a reaction mixture comprising, at least one acrylic monomer having acid-functionality and / or at least one acrylic monomer having a group capable of reacting with another material to provide acid functionality. For example, the acrylic material may comprise, i.e., be formed from a reaction mixture comprising, at least one acrylic monomer having acid-functionality.

[0031] The acrylic material may comprise at least 10 wt%, such as at least 20 wt%, such as at least 30 wt%, such as at least 40 wt%, such as at least 50 wt%, such as at least 60 wt%, such as at least 70 wt%, such as at least 75 wt% acrylic monomer, such as at least 80 wt%, such as at least 85 wt%, such as at least 90 wt%, such as at least 95 wt%, such as at least 97 wt%, such as at least 98 wt%, such as at least 99 wt%, or even >99 wt%, for example, at least 99.1 wt%, at least 99.5 wt% or at least 99.9 wt% acrylic monomer based on the total solid weight of the monomers from which the acrylic material is formed. The acrylic material may comprise 100 wt% acrylic monomer based on the total solid weight of the monomers from which the acrylic material is formed.

[0032] The acrylic material may be formed from a reaction mixture comprising acrylic acid and / or methacrylic acid, for example acrylic acid.

[0033] The acrylic material may be formed from a reaction mixture comprising an acid-functional acrylic monomer, a hydroxy-functional acrylic monomer, a multi-ethylenically unsaturated monomer, an alkyl (alk)acrylate, and optionally styrene.

[0034] The acrylic material may be formed from a reaction mixture comprising acrylic acid, hydroxyethyl acrylate, allyl methacrylate, butyl methacrylate, methyl methacrylate, and optionally styrene.

[0035] The acrylic material has an acid value below 50 mg KOH / g. For example, the acrylic material may have an acid value up to 49, 48, 47, 46, or even 45 mg KOH / g.

[0036] The acrylic material may have an acid value at least 5 mg KOH / g. For example, the acrylic material may have an acid value of at least 10 mg KOH / g, such as at least 15 mg KOH / g, such as at least 20 mg KOH / g, such as at least 25 mg KOH / g, such as at least 30 mg KOH / g, such as at least 35 mg KOH / g, such as at least 40 mg KOH / g.

[0037] The acrylic material may have an acid value from 5 to less than 50 mg KOH / g, such as from 10 to less than 50 mg KOH / g, such as from 15 to less than 50 mg KOH / g, such as from 15 to less than 50 mg KOH / g, such as from 20 to less than 50 mg KOH / g, such as from 25 to less than 50 mg KOH / g, such as from 30 to less than 50 mg KOH / g, such as from 35 to less than 50 mg KOH / g. The acrylic material may have an acid value from 5 to 49 mg KOH / g, such as from10 to 49 mg KOH / g, such as from 15 to 49 mg KOH / g, such as from 15 to 49 mg KOH / g, such as from 20 to 49 mg KOH / g, such as from 25 to 49 mg KOH / g, such as from 30 to 49 mg KOH / g, such as from 35 to 49 mg KOH / g. The acrylic material may have an acid value from 5 to 48 mg KOH / g, such as from 10 to 48 mg KOH / g, such as from 15 to 48 mg KOH / g, such as from 15 to 48 mg KOH / g, such as from 20 to 48 mg KOH / g, such as from 25 to 48 mg KOH / g, such as from 30 to 48 mg KOH / g, such as from 35 to 48 mg KOH / g. The acrylic material may have an acid value from 5 to 47 mg KOH / g, such as from 10 to 47 mg KOH / g, such as from 15 to 47 mg KOH / g, such as from 15 to 47 mg KOH / g, such as from 20 to 47 mg KOH / g, such as from 25 to 47 mg KOH / g, such as from 30 to 47 mg KOH / g, such as from 35 to 47 mg KOH / g. The acrylic material may have an acid value from 5 to 46 mg KOH / g, such as from 10 to 46 mg KOH / g, such as from 15 to 46 mg KOH / g, such as from 15 to 46 mg KOH / g, such as from 20 to 46 mg KOH / g, such as from 25 to 46 mg KOH / g, such as from 30 to 46 mg KOH / g, such as from 35 to 46 mg KOH / g. The acrylic material may have an acid value from 5 to 45 mg KOH / g, such as from 10 to 45 mg KOH / g, such as from 15 to 45 mg KOH / g, such as from 15 to 45 mg KOH / g, such as from 20 to 45 mg KOH / g, such as from 25 to 45 mg KOH / g, such as from 30 to 45 mg KOH / g, such as from 35 to 45 mg KOH / g.

[0038] As reported herein, the acid value (AV) expressed on solids was determined by titration with 0.1 M methanolic potassium hydroxide (KOH) solution. A sample of solid polymer (0.1 to 3 g depending on acid number) was weighed accurately into a conical flask and is dissolved, using light heating and stirring as appropriate, in 25 ml of dimethyl formamide containing phenolphthalein indicator. The solution was then cooled to room temperature and titrated with the 0.1 M methanolic potassium hydroxide solution. The resulting acid number is expressed in units of mg KOH / g and is calculated using the following equation:Acid value = titre of KOH solution (ml) x molarity KOH solution (M) x 56.1 weight of solid sample (g)

[0039] All values for acid value reported herein were measured in this way unless specified otherwise.

[0040] The acrylic material may have pendant hydroxyl groups such that it is hydroxyl-functional.

[0041] The acrylic material may have any suitable hydroxyl value (OHV; also known as hydroxyl number or ‘OHN’).

[0042] The acrylic material may have a hydroxyl value from 0 to 200 mg KOH / g, such as from 5 to 150 mg KOH / g, from 10 to 100 mg KOH / g, such as from 10 to 50 mg KOH / g, such as from 10 to 40 mg KOH / g, such as from 10 to 30 mg KOH / g.

[0043] All values for hydroxyl value provided herein are expressed on solids unless specified otherwise. As reported herein, the hydroxyl number expressed on solids is the number of mg of KOH equivalent to the hydroxyl groups in 1 g of material. In such as method, a sample (typically, 0.1 to 3 g) was weighed accurately into a conical flask and is dissolved, using lightheating and stirring as appropriate, in 20 ml of tetrahydrofuran. 10 ml of 0.1 M 4- (dimethylamino)pyridine in tetrahydrofuran (catalyst solution) and 5 ml of a 9 vol% solution of acetic anhydride in tetrahydrofuran (i.e. 90 ml acetic anhydride in 910 ml tetrahydrofuran; acetylating solution) were then added to the mixture. After 5 minutes, 10 ml of an 80 vol% solution of tetrahydrofuran (i.e. 4 volume parts tetrahydrofuran to 1 part distilled water; hydrolysis solution) was added. After 15 minutes, 10 ml tetrahydrofuran was added and the solution is titrated with 0.5 M ethanolic potassium hydroxide (KOH). A blank sample was also run where the sample of solid polyester is omitted. The resulting hydroxyl number is expressed in units of mg KOH / g and is calculated using the following equation:Hydroxyl number = ((V2 - Vi) x molarity of KOH solution (M) x 56.1) / weight of solid sample (g) wherein Vi is the titre of KOH solution (ml) of the polyester sample and V2 is the titre of KOH solution (ml) of the blank sample.

[0044] All values for acid value reported herein were measured in this way unless specified otherwise.

[0045] The acrylic material may have any suitable number average molecular weight (Mn). The acrylic material may have an Mn of at least 500 Daltons (Da = g / mole), such as at least 1,000 Da, such as at least 2,000 Da, such as at least 3,000 Da, such as at least 4,000 Da, such as at least 5,000 Da. The acrylic material may have an Mn up to 250,000 Da, such as up to 200,000 Da, such as up to 150,000 Da, such as up to 100,000 Da, such as up to 50,000 Da, such as up to 25,000 Da, such as up to 20,000 Da, such as up to 15,000 Da, such as up to 10,000 Da, such as up to 9,000 Da, such as up to 8,000 Da, such as up to 7,000 Da, such as up to 6,000 Da. The acrylic material may have an Mn from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 250,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 200,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 1500,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 100,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 50,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 25,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 20,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 15,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 10,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 9,000 Da, such as from such as from 500, 1,000, 2,000, 3,000, 4,000 or 5,000 to 8,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 7,000 Da, such as from 500, 1 ,000, 2,000, 3,000, 4,000 or 5,000 to 6,000 Da.

[0046] As reported herein, the Mn was determined by gel permeation chromatography using a polystyrene standard according to ASTM D6579-11 (“Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size Exclusion Chromatography”. Rl detector, solvent: unstabilised THF, retention time marker:toluene, sample concentration: 10mg / ml). All values for Mn reported herein were measured in this way unless specified otherwise.

[0047] The acrylic material may have any suitable weight-average molecular weight (Mw).

[0048] The acrylic material may have an Mw of at least 500 Daltons (Da= g / mole), such as at least 1 ,000 Da, such as at least 2,000 Da, such as at least 5,000 Da, such as at least 6,000 Da, such as at least 7,000 Da, such as at least 8,000 Da, such as at least 9.000 Da, such as at least 10,000 Da, such as at least 20,000 Da, such as at least 30,000 Da, such as at least 40,000 Da, such as at least 50,000 Da, such as at least 60,000 Da, such as least 70,000 Da, such as at least 80,000 Da, such as at least 90,000 Da, such as at least 100,000 Da.

[0049] As reported herein, the Mw was determined by gel permeation chromatography using a polystyrene standard according to ASTM D6579-11 (“Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size Exclusion Chromatography”. Rl detector, solvent: unstabilised THF, retention time marker: toluene, sample concentration: 10 mg / ml).

[0050] All values for Mw reported herein were measured in this way.

[0051] The acrylic material may have any suitable polydispersity index (PDI), i.e. the ratio of Mw / Mn. The acrylic material may have a polydispersity index of at least 4, such as at least 5, such as at least 6, such as at least 7, such as at least 8, such as at least 9, such as at least 10.

[0052] A person skilled in the art will appreciate that techniques to measure the number-average molecular weight may also be applied to measure the weight-average molecular weight.

[0053] The acrylic material may have any suitable glass transition temperature (Tg).

[0054] The acrylic material may have a Tg from -10 to 100°C, such as from -5 to 50°C, such as from 0 to 40°C, such as from 10 to 40°C, such as from 10 to 30°C, such as from 10 to 20°C.

[0055] As reported herein, the Tg was measured according to ASTM D6604-00(2013) (“Standard Practice for Glass Transition Temperatures of Hydrocarbon Resins by Differential Scanning Calorimetry”. Heat-flux differential scanning calorimetry (DSC), sample pans: aluminium, reference: blank, calibration: indium and mercury, sample weight: 10 mg, heating rate: 20°C / min).

[0056] All values for Tg reported herein were measured in this way.

[0057] The acrylic material may comprise one acrylic polymer or may comprise a blend of two or more acrylic polymers. For example, the acrylic material may comprise a blend of two acrylic polymers. The acrylic material may comprise a blend of an acrylic polymer formed from a reaction mixture containing styrene and an acrylic polymer formed from a reaction mixture substantially free of styrene (or a “styrene-free acrylic polymer” and a “styrene-containing acrylic polymer”). The ratio of styrene-containing acrylic polymer to styrene-free acrylic polymer may be from 5:1 to 1 :5, such as from 4:1 to 1 :4, such as from 3:1 to 1 :3, such as from 2:1 to 1 :2. The ratio of styrene-containing acrylic polymer to styrene-free acrylic polymer may be 1 :1.

[0058] The post repair coating composition may comprise any suitable amount of the acrylic material. The post repair coating composition may comprise at least 50 wt%, such as at least60 wt%, such as at least 70 wt%, such as at least 75 wt%, such at least 80 wt% of the acrylic material based on the total solid weight of the composition.

[0059] The post repair coating composition may comprise up to 99.9 wt%, suitably up to 99 wt%, such as up to 98 wt%, such as up to 97 wt%, such as up to 96 wt%, such as up to 95 wt%, such as up to 92 wt%, such as up to 90 wt% of the acrylic material based on the total solid weight of the composition.

[0060] The post repair coating composition may comprise from 50 to 99.9 wt%, such as from 70 to 99.9 wt%, such as from 75 to 99.9 wt%, such as from 80 to 99.9 wt%, such as from 85 to 99.9 wt%, such as from 90 to 99.9 wt% of the acrylic material based on the total solid weight of the composition. The post repair coating composition may comprise from 50, 60, 70, 75 or 80 wt% to 99.9 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 99 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 98 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 97 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 96 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 95 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 92 wt% of the acrylic material based on the total solid weight of the composition, such as from 50, 60, 70, 75 or 80 wt% to 90 wt% of the acrylic material based on the total solid weight of the composition.

[0061] The acrylic material may comprise a solution polymerised acrylic material and / or an emulsion polymerised acrylic material. As used herein, “solution polymerised” means a polymer that is formed by a polymerisation method whereby a monomer is substantially dissolved in a solvent and polymerised. Once said monomer has been polymerised, the resultant solution polymerised acrylic material is suitably substantially soluble in said solvent.

[0062] The acrylic material may be formed by a solution polymerisation method. Suitable solution polymerisation methods will be well to a person skilled in the art. The solution polymerisation method comprises a plurality of components, which may be referred to as a solution polymerisation reaction mixture.

[0063] The solution polymerisation reaction mixture may comprise a monomer component. The monomer component may comprise one or more acrylic monomer(s) as described above. The monomer component may optionally comprise one or more additional ethylenically unsaturated monomer(s) as described above.

[0064] The solution polymerisation reaction mixture may further comprise an initiator. The initiator may be a free radical initiator. Examples of suitable initiators include, but are not limited to, tertiary butyl perbenzoate; tert butyl peroxy 3,5,5 trimethylhexanoate; tertiary butyl peroxy 2- ethyl hexanoate; T-amyl peroxy 2-ethyl hexanoate; di tertiary butyl peroxide; tertiary butyl peracetate; tertiary butyl peroctoate; azo type initiators such as, for example, 2,2’-azobis(isobutyronitrile), 2,2'-Azobis(2-methylbutyronitrile), 2,2'-Azobis(2.4-dimethyl valeronitrile) and 2,2'-Azobis(4-methoxy-2.4-dimethyl valeronitrile); persulphate initiators such as, for example, ammonium persulphate, sodium persulphate or potassium persulphate; and combinations thereof. The initiator may comprise 2,2'-Azobis(2-methylbutyronitrile). The initiator may be soluble in the solution polymerisation reaction mixture. The initiator may be soluble in the monomer component.

[0065] The solution polymerisation reaction mixture may comprise a solvent or mixture of solvents. Suitable solvents will be well known to a person skilled in the art. Examples of suitable solvents include, but are not limited to, aliphatic hydrocarbons such as mineral spirits and high flash point naphtha; 2,2-dimethoxypropane (DMP); Rhodiasolv (RTM) RPDE commercially available from Solvay; methyl ethyl ketone; methyl isobutyl ketone; cyclohexanone; aromatic hydrocarbons such as benzene; toluene; xylene; solvent naphtha 100, 150, 150ND, 200 and / or 200ND; those sold under the tradename SOLVESSO (RTM) commercially available from Exxon-Mobil Chemical Company; alcohols such as, for example, propanol, isopropanol, n- butanol, pentanol, hexanol or diacetone alcohol; glycols such as, for example, butyl glycol; glycol ethers such as, for example, 2-butoxy ethanol, 1 -methoxy propan-2-ol; esters such as, for example, ethyl acetate, butyl acetate, n-hexyl acetate, dibasic ester commercially available from Sigma Aldrich, propylene glycol methyl ether acetate, butyl glycol acetate and butyl diglycol acetate; glycols such as butyl glycol and dibutyl glycol; glycol ethers such as methoxypropanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol methyl ether and dipropylene glycol mono methyl ether; and combinations thereof. The solvent may comprise a mixture of solvents, such as n-butanol and butyl glycol, for example. It will be appreciated by a person skilled in the art that the solvent or mixture of solvents may be chosen such that the monomer component is substantially soluble in said solvent or mixture of solvents.

[0066] The solution polymerisation reaction mixture may be substantially free, may be essentially free or may be completely free of alcohol solvents. By “substantially free’’ we mean to refer to reaction mixtures comprising less than 10 vol% alcohol solvents based on the total volume of solvent present. By “essentially free” we mean to refer to reaction mixtures comprising less than 5 vol% alcohol solvents based on the total volume of solvent present. By “completely free” we mean to refer to reaction mixtures comprising less than 1 vol% alcohol solvents based on the total volume of solvent present. The solution polymerisation reaction mixture may comprise 0 vol% alcohol solvent based on the total volume of solvent present. By using 0 wt% alcohol solvent in the solution polymerisation reaction mixture, the initiation of lactone and / or lactide polymerisation may be reduced or eliminated.

[0067] The monomer component is caused to undergo polymerisation in the solvent or mixture of solvents to form the acrylic material. The solution polymerisation of the monomer component may be carried out as a free radical initiated solution polymerisation in a solvent or mixture of solvents.

[0068] Solution polymerisation may be carried out in a suitable reaction vessel. The monomer component, initiator and / or solvent or mixture of solvents may be added to the reaction vessel in any suitable order. For example, the solvent or mixture of solvents may be added to the reaction vessel before the monomer component and / or initiator are added to the reaction vessel. The monomer component and initiator may be added to the reaction vessel at the same time. The monomer component and / or initiator may be added to the reaction vessel over any suitable period of time. The monomer component and / or initiator may be added to the reaction vessel over a time period of 0 to 12 hours, such as 30 minutes to 8 hours, such as 1 hour to 6 hours, or even 2 hours to 4 hours. For the avoidance of doubt, when the monomer component and / or initiator are added over a time period of 0 hours, all of the monomer component and / or initiator are added at the same time (i.e. in one single addition).

[0069] Solution polymerisation may be carried out at any suitable temperature. Solution polymerisation may be carried out at an elevated temperature. Solution polymerisation may be carried out at a temperature from 80°C to 200°C, such as from 80°C to 180°C, such as from 80°C to 160°C, such as from 80°C to 150°C, such as from 80°C to 140°C, such as from 80°C to 130°C, such as from 80°C to 120°C, such as 80°C to 110°C, or even from 90°C to 110°C. Solution polymerisation may be carried out at a temperature from 90°C to 110°C. Solution polymerisation may be carried out at reflux. Solution polymerisation may be carried out at a temperature of 80°C or above, such as 100°C or above, such as 120°C or above, such as 130°C or above, or even 135°C or above. Solution polymerisation may be carried out at a temperature of 250°C or below, such as 200°C or below, such as 180°C or below, such as 160°C or lower, such as 150°C or lower, or even 145°C or lower.

[0070] The acid-functional acrylic material may be prepared by emulsion polymerisation. Suitable emulsion polymerisation methods will be well known to a person skilled in the art. The emulsion polymerisation method may comprise a plurality of components, which may be referred to as an emulsion polymerisation reaction mixture.

[0071] The acrylic material may be formed by a two-stage solution polymerisation process. The two-stage process may comprise the formation of a hydroxy functional acrylic material in the first stage and an acid-functional acrylic material in the second stage.

[0072] The second stage of the two-stage process may comprise reacting the hydroxy functional acrylic material with a mixture of acrylic monomers including an acrylic monomer containing carboxylic acid groups. Examples of suitable acrylic monomers are listed above.

[0073] The hydroxy functional acrylic material may be prepared using known free radical polymerizing methods carried out in organic solvent. Examples of suitable solvents are alcohols such as n-butanol, isopropanol and glycol monoalkyl ethers such as 2-butoxy ethanol, including mixtures thereof. Examples of free radical initiators include peroxides, peresters and azobiscarbonitriles. Specific examples are t-butyl peroxide, t-butyl peroctoate and 2,2'-azobis(2- methyl isobutyronitrile). Typically, a monomer mixture and initiator are added to the reaction vessel over a period of about 0.5 to 3 hours with a polymerization temperature of 80 to 150°C.

[0074] A mixture of acrylic monomers including an acid-functional acrylic monomer may be reacted with the hydroxy functional acrylic material. Examples of acid-functional acrylic monomers are as defined herein, such as (meth)acrylic acid, itaconic acid and cratonic acid. These monomers are typically used in amounts of 20 to 60 percent by weight based on total weight of the acrylic monomers present in the mixture of acrylic monomers. Other monomers are usually included in the mixture of acrylic monomers. Examples include vinyl aromatic monomers, such as styrene and vinyl toluene, and alkyl esters of (meth)acrylic acid containing from 1 to 12 carbon atoms in the alkyl group. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate and lauryl (meth)acrylate.

[0075] The reaction product of the hydroxy functional acrylic material with the acrylic monomers is typically done by adding the mixture of acrylic monomers with free radical initiator as described above to the hydroxy functional acrylic material dissolved or dispersed in organic solvent such as those mentioned above. The time and temperature of the reaction is generally as described above.

[0076] The relative amounts of hydroxy functional acrylic material and acrylic monomers may be within the range of 50 to 80 percent of hydroxy functional acrylic material and 20 to 50 percent of acrylic monomers, the percentages being by weight based on total weight of hydroxy functional acrylic material and acrylic monomers.

[0077] The emulsion polymerisation reaction mixture may comprise an emulsion polymerisation monomer component. The emulsion polymerisation monomer component comprises one or more acrylic monomer(s) as described above. The emulsion polymerisation monomer component may optionally comprise additional ethylenically unsaturated monomer(s) as described above.

[0078] The emulsion polymerisation reaction mixture may further comprise an initiator. Suitable initiators are as described above (in relation to solution polymerisation methods).

[0079] The emulsion polymerisation reaction mixture comprises water.

[0080] The monomer component of the emulsion polymerisation reaction mixture may be caused to undergo polymerisation in the water to form the acid-functional acrylic polymer particles. Thus, the polymerisation of the monomer component of the emulsion polymerisation reaction mixture is typically carried out as a free radical initiated emulsion polymerisation in water. The monomer component of the emulsion polymerisation reaction mixture may form an oil phase in the water.

[0081] The emulsion polymerisation reaction mixture may comprise a buffer. Suitable buffers will be well known to a person skilled in the art. The buffer may be operable to act as a hydrogen ion acceptor. Examples of suitable buffers include, but are not limited to, sodium bicarbonate.

[0082] The emulsion polymerisation reaction mixture may comprise a surfactant. The surfactant may be an anionic, cationic or non-ionic type stabilizer. Suitable examples of anionic surfactants include, but are not limited to, alkyl sulphates such as, for example, sodium dodecyl sulphate or sodium polyoxy ethylene alkyl ether sulphate; aryl sulphonates such as, for example, sodiumdodecylbenzene sulphonate; sulphosuccinates such as, for example, sodium diisobutyl sulpho succinate, sodium dioctyl sulpho succinate and sodium di cyclohexyl sulpho succinate; and combinations thereof. Suitable examples of nonionic emulsifiers include, but are not limited to, fatty alcohol ethoxylates such as, for example polyethylene glycol mono lauryl ether; fatty acid ethoxylates such as, for example, polyethylene glycol mono stearate or polyethylene glycol mono laurate; polyether block polymers such as, for example, polyethylene glycol / polypropylene glycol block polymers also known as pluronics, typical commercial products of this type include Tergitol XJ, XH or XD commercially available from Dow Chemical; and combinations thereof. Suitable examples of cationic emulsifiers include, but are not limited to, amine salts such as, for example, cetyl trimethyl ammonium chloride or benzyl dodecyl dimethyl ammonium bromide; and combinations thereof. It will be appreciated by a person skilled in the art that mixtures of anionic and cationic emulsifiers would typically not be desirable.

[0083] However, the emulsion polymerisation reaction mixture may be substantially free, may be essentially free or may be completely free of surfactant. By substantially free in relation to surfactants, is meant that the emulsion polymerisation reaction mixture comprises less than 5 wt% of surfactant based on the total weight of the emulsion polymerisation reaction mixture. By essentially free in relation to surfactants, is meant that the emulsion polymerisation reaction mixture comprises less than 1 wt% of surfactant based on the total weight of the emulsion polymerisation reaction mixture. By completely free in relation to surfactants, is meant that the emulsion polymerisation reaction mixture comprises less than 0.01 wt% of surfactant based on the total weight of the emulsion polymerisation reaction mixture. The emulsion polymerisation reaction mixture may comprise no, i.e., 0 wt%, surfactant.

[0084] The surfactant may be polymeric. The surfactant may be polymerisable with the emulsion polymerised acrylic latex material. For example, the surfactant may be polymerisable with the monomers that form the acid-functional acrylic polymer particles.

[0085] The emulsion polymerisation reaction mixture may comprise a neutraliser. Suitable neutralisers are as described above (in relation to solution polymerisation methods). A neutraliser may be added to at least of portion of the emulsion polymerisation monomer component. A neutraliser may be added to at least a portion of the emulsion polymerisation monomer component prior to the polymerisation reaction, i.e., prior to the emulsion polymerisation monomer component contacting the initiator.

[0086] Advantageously, when the acid-functional acrylic polymer particles are formed by an emulsion polymerisation method, the acid-functional acrylic polymer particles may be prepared in the absence of surfactants.

[0087] Emulsion polymerisation is typically carried out in a suitable reaction vessel. The emulsion polymerisation monomer component, initiator and / or water of the emulsion polymerisation reaction mixture may be added to the reaction vessel in any suitable order. For example, the water may be added to the reaction vessel before the emulsion polymerisation monomer component and / or initiator are added to the reaction vessel. The initiator may beadded to the reaction vessel before the emulsion polymerisation monomer component. The emulsion polymerisation monomer component and / or initiator may be added to the reaction vessel over any suitable period of time. The emulsion polymerisation monomer component and / or initiator may be added to the reaction vessel over a time period of from 0 to 24 hours, such as from 30 minutes to 12 hours, such as from 1 hour to 10 hours, such as from 2 hours to 10 hours, or even from 2 to 6 hours. For the avoidance of doubt, when the emulsion polymerisation monomer component and / or initiator are added over a time period of 0 hours, all of the emulsion polymerisation monomer component and / or initiator are added at the same time (i.e., in a single addition).

[0088] The emulsion polymerisation monomer component may be added at any suitable rate during the time period for addition of the emulsion polymerisation monomer component. The emulsion polymerisation monomer component may be added at a constant rate or the emulsion polymerisation monomer component may be added at a variable rate during the time period for addition of the emulsion polymerisation monomer component. The emulsion polymerisation monomer component may be added dropwise. By the term ‘dropwise' and like terms as used herein is meant, unless specified otherwise, that the emulsion polymerisation monomer component is added at a rate of from 0.05 to 1.0 wt% / minute over a period of time, T, based on the total solid weight of the monomers in the emulsion polymerisation monomer component. The emulsion polymerisation monomer component may be added at a rate which results in a low level of free monomer in the emulsion polymerisation reaction mixture. The emulsion polymerisation monomer component may be added at a rate which reduces or substantially prevents the monomers of the emulsion polymerisation monomer component from being insoluble in the emulsion polymerisation reaction mixture. In other words, the emulsion polymerisation monomer component may be added at a suitable rate such that the monomers of the emulsion polymerisation monomer component are and / or remain substantially dissolved in the emulsion polymerisation reaction mixture.

[0089] The monomer component may be added at a variable rate during the time period for addition of the monomer component. The monomer component may be added at a slower rate initially and then at an increasingly faster rate during the time period for addition of the monomer component.

[0090] Emulsion polymerisation may be carried out at any suitable temperature. Emulsion polymerisation may be carried out at a temperature from 20°C to 150°C, such as from 40°C to 120°C, such as from 50°C to 100°C, such as from 60°C to 95°C, or even from 70°C to 90°C. Emulsion polymerisation may be carried out at a temperature of 80°C. The temperature is typically held constant throughout the emulsion polymerisation process.

[0091] The acid-functional acrylic polymer particles may be in a core / shell arrangement.

[0092] The shell may be formed from a plurality of components, which may be referred to as a shell mixture. The shell mixture comprises one or more acrylic monomer(s) as described above.The emulsion polymerisation reaction mixture may optionally comprise one or more additional ethylenically unsaturated monomer(s) as described above.

[0093] The shell mixture may further comprise one or more initiator(s). Suitable initiators are as described above in relation to the acrylic material.

[0094] The shell mixture may be caused to undergo polymerisation to form a shell polymer. The polymerisation of the shell mixture may typically be carried out as a free radical initiated solution polymerisation in a solvent or mixture of solvents. The solvents which may be used in this process include, but are not limited to, alcohols such as n- butanol, pentanol or hexanol; or glycol ethers such as 2-butoxy ethanol, 1 -methoxy propan-2-ol or dipropylene glycol mono methyl ether. Polymerisation may be carried out at an elevated temperature. Typically, the polymerisation may be carried out in the range 80°C to 150°C. The polymerisation can be effectively carried out by adding the shell mixture, over a set time period, to the solvent mixture. The shell mixture may be caused to undergo polymerisation to form a shell polymer prior to contact with components of the core mixture.

[0095] Where the shell mixture comprises one or more a,p-ethylenically unsaturated carboxylic acid(s), the shell polymer will have pendant carboxylic acid functional groups. This may be referred to a carboxylic acid functional shell polymer.

[0096] The carboxylic acid functional shell polymer may be contacted with a base to form a water dispersible salt. The carboxylic acid functionality in the carboxylic acid functional shell polymer may be at least partly neutralised with the base. Typically, at least 10% of the available carboxylic acid groups are neutralised. Substantially all of the available carboxylic acid groups may be neutralised by the base. The base used for this neutralisation may comprise an amine functional material, or a mixture of amine functional materials. Examples of suitable amine functional materials include, but are not limited to, ammonia, triethylamine, diethylamine, trimethylamine and morphline or hydroxy amine materials such as ethanol amine, N-methyl ethanol amine and N,N-di methyl ethanolamine.

[0097] The shell polymer may be dispersed in aqueous medium. In this manner, an aqueous dispersion or solution of the shell polymer may be formed.

[0098] The shell mixture may be caused to undergo polymerisation to form a shell polymer by emulsion polymerisation in an aqueous medium, thereby forming an aqueous dispersion or solution of the shell polymer.

[0099] The core may be formed from plurality of components, which may be referred to as a core mixture. The core mixture may comprise one or more acrylic monomer(s) as described above. The emulsion polymerisation reaction mixture may optionally comprise one or more additional ethylenically unsaturated monomer(s) as described above.

[0100] The polymer formed from the shell mixture, such as an aqueous dispersion thereof, may serve as a dispersant for a subsequent polymerisation, which may be a polymerisation of an a, p-ethylenically unsaturated monomer mixture, such as the core mixture.

[0101] The core mixture may further comprise one or more one or more initiator(s). Suitable initiators are as described above (in relation to solution polymerisation methods).

[0102] The core mixture may be caused to undergo polymerisation at a temperature in the range from 30°C to 99°C, such as in the range from 50°C to 95°C, such as in the range from 80°C to 90°C. Polymerisation of the core mixture may occur in the presence of the polymer formed by polymerisation of the shell mixture to thereby form a core / shell polymer, typically by emulsion polymerisation. A typical polymerisation may be carried out by adding the core mixture, at a controlled rate over a period of time, to an aqueous dispersion of shell polymer. During the polymerisation the mixture may be mixed, such as by stirring and the temperature may be held generally constant.

[0103] Other methods to polymerise the core mixture include, but are not limited to, mixing all or part of the core ethylenically unsaturated substances with the aqueous dispersion of shell polymer and then adding the remaining core components, including initiator, to the resulting mixture over a set period of time. Suitable temperatures for this type of process are typically in the range 50°C to 95°C.

[0104] For the core / shell latex composition the ratio of the core mixture (monomers and initiator) to shell mixture (monomers and initiator) may be from 20:80 to 90:10 by weight. The ratio of the core mixture to shell mixture may be from 60:40 to 80:20 by weight, the ratio of the core mixture to shell mixture components may be from 70:30 to 75:25.

[0105] The acid functionality of the acrylic material may be at least partially neutralised with a suitable neutraliser. Suitable neutralisers will be well known to a person skilled in the art. Examples of suitable neutralisers include, but are not limited to tertiary amines such as, for example, dimethylethanolamine (DMEA), trimethyl amine, methyl diethanol amine, ethyl methyl ethanol amine, dimethyl ethyl amine, dimethyl propyl amine, dimethyl 3-hydroxy-1 -propyl amine, dimeythylbenzyl amine, dimethyl 2-hydroxy-1 -propyl amine, diethyl methyl amine, dimethyl 1- hydroxy-2-propyl amine, triethyl amine, tributyl amine, N-methyl morpholine; ammonia; hydrazine; metallic aluminium; metallic zinc; water-soluble oxides of the elements Li, Na, K, Mg, Ca, Fe(ll) and Sn(ll); water-soluble hydroxides of the elements Li, Na, K, Mg, Ca, Fe(ll) and Sn(ll); water-soluble carbonates of the elements Li, Na, K, Mg, Ca, Fe(ll) and Sn(ll);and combinations thereof. The neutraliser may comprise a tertiary amine. The neutraliser may comprise dimethylethanolamine (DMEA).

[0106] The coating composition may comprise any suitable amount of neutraliser. The amount of neutraliser may be a suitable amount to neutralise the acid functionality such that the acrylic material disperses in water. The amount of neutraliser may be a suitable amount to neutralise at least 10%, suitably at least 20%, such as at least 30%, such as at least 40%, or even at least 50% of the acid functionality of the acrylic material. By, for example, ‘neutralise at least 20%' is meant that at least 20% of the available acid groups of the acrylic material are neutralised. A person skilled in the art will therefore appreciate that at least 30%, at least 40%, at least 50% neutralised etc. means that at least 30%, at least 40%, at least 50% of the available acid groupsof the acrylic material are neutralised. The acid functionality of the acrylic material may be 50% neutralised with the neutraliser. For example, at least 0.1 , at least 0.2, at least 0.3, such as at least 0.4, or even at least 0.5 equivalents of neutraliser may be added to the acrylic material per equivalent of acid groups.

[0107] The post repair coating composition of the present invention comprises a crosslinker material. The crosslinker material is formed from reactants that are substantially free of formaldehyde. The crosslinker material may be essentially free or may be completely free of formaldehyde. By “substantially free” we mean to refer to crosslinker materials formed from reactants that contain less than 1000 parts per million (ppm) of any of the compounds or derivatives thereof mentioned above. By “essentially free” we mean to refer to crosslinker materials formed from reactants that contain less than 100 ppm of any of the compounds or derivatives thereof mentioned above. By “completely free” we mean to refer to crosslinker materials formed from reactants that contain less than 20 parts per billion (ppb) of any of the compounds or derivatives thereof.

[0108] The crosslinker material may be formed from reactants that contain 0wt% of formaldehyde. Thus, the crosslinker material may be formed from reactants that do not include formaldehyde.

[0109] The crosslinker material may suitably be operable to crosslink acid functionality on the acrylic material. Suitable crosslinker materials operable to crosslink acid functionality on the acrylic material include, but are not limited to, the following: amino resins; epoxy resins; epoxymimic resins, such as those based on bisphenols and other bisphenol A (BPA) replacements; isocyanate resins, isocyanurate resins, such as triglycidylisocyanurate; hydroxy (alkyl) amide resins, such as p-hydroxy (alkyl) amide resins; hydroxy(alkyl) urea resins; carbodiimide resins, such as polycarbodiimide resins; oxazolines; and combinations thereof.

[0110] The crosslinker material may comprise a hydroxy (alkyl) amide material, such as a p- hydroxy (alkyl) amide material, a hydroxy(alkyl) urea material and / or a carbodiimide material.

[0111] The crosslinker material may comprise a carbodiimide material. The carbodiimide material may comprise any suitable carbodiimide material. The carbodiimide material may comprise a polycarbodiimide resin. The crosslinker material may be in the form of a carbodiimide resin. The crosslinker material may comprise a polycarbodiimide.

[0112] Suitable carbodiimide materials will be known to a person skilled in the art. For example, examples of suitable carbodiimide crosslinker materials are disclosed in WO2017 / 122171 , the entire contents of which are incorporated herein by reference, and in particular in paragraphs

[0005] ,

[0006] and

[0021] to

[0041] of WO2017 / 122171.

[0113] The carbodiimide material may be commercially available. Examples of suitable commercially available carbodiimide materials include, but are not limited to, those sold under the trade name Picassian (RTM) commercially available from Stahl Holdings B.V., such as Picassian XL-755, Picassian XL-76, Picassian XL-701 , Picassian XL-701 , Picassian XL-702,Picassian XL-721 , Picassian XL-725, Picassian XL-732, Picassian XL-752, Picassian XL-755, and Picassian XL-762.

[0114] Non limiting examples of isocyanate resins include, but are not limited to, isophorone diisocyanate (IPDI), such as those sold under the trade name DESMODUR (RTM) commercially available from Covestro, for example DESMODUR VP-LS 2078 / 2 or DESMODUR PL 340 or those sold under the trade name VESTANAT (RTM) commercially available from Evonik, for example VESTANANT B 1370, VESTANAT B 118 6A or VESTANAT B 1358 A; blocked aliphatic polyisocyanate based on hexamethylene diisocyanate (H DI), such as those sold under the trade name DESMODUR (RTM) commercially available from Covestro, for example DESMODUR BL3370 or DESMODUR BL 3175 SN, those sold under the trade name DURANATE (RTM) commercially available from Asahi KASEI, for example DURANATE MF- K60X, those sold under the trade name TOLONATE (RTM) commercially available from Perstorp, for example TOLONATE D2 or those sold under the trade name TRIXENE (RTM) commercially available from Baxenden, for example TRIXENE-BI-7984 or TRIXENE 7981 ; or combinations thereof.

[0115] The crosslinker material may contain nitrogen, which may be in the form of an amine or amide material. The crosslinker material may comprise a hydroxyl substituted amine or amide material. The crosslinker material may comprise a hydroxyalkylamide material, such as a p- hydroxyalkylamide material. Examples of suitable hydroxyalkylamide materials are disclosed in WO 2017 / 121879, the entire contents of which is incorporated herein by reference, and in particular from page 13, line 4 to page 14, line 11 of WO 2017 / 121879.

[0116] The hydroxyalkylamide crosslinker may comprise a polyhydroxyalkylamide material, such as a polyhydroxyalkylamide having the Formula (VI):Formula (VI) wherein, with reference to Formula (VI), Z represents a polymer or an alkylene, alkenylene, alkynylene or arylene group; Z' represents a bivalent organic linking group; m is 0 or 1 ; X represents a bivalent organic bridging group; R represents a hydroxyalkylamide group; and n is at least 2.

[0117] Examples of suitable polyhydroxyalkylamide materials are disclosed in W02020 / 123893, the entire contents of which are incorporated herein by reference.

[0118] The crosslinker material may be in the form of a urea material. The crosslinker material may comprise a hydroxyl substituted urea material.

[0119] The crosslinker material may comprise a hydroxy functional alkyl polyurea material.

[0120] The crosslinker material may contain a terminal chemical group as shown in Formula (VII).Formula (VII) wherein Y5and Y6each, independently, represent hydrogen, an alkyl or a hydroxy functional alkyl having two or more carbon atoms and at least one of Y5and Y6is a hydroxyl functional alkyl having two or more carbon atoms.

[0121] The Y5and Y6groups may exclude ether linkages.

[0122] The terminal chemical group of Formula (VII) may be connected to a further chemical structure, not shown. Additionally or alternatively, the chemical group of Formula (VII) may be suspended from a carrier substrate, such as a silica carrier substrate, for example.

[0123] The crosslinker material may contain a plurality of terminal chemical groups as shown in Formula (VII). For example, the crosslinker may contain 2 to 6 terminal chemical groups as shown in Formula (VII), such as 2, 3 or 4 terminal chemical groups as shown in Formula (VII).

[0124] Examples of suitable hydroxy functional alkyl polyureas are disclosed in WO2017 / 123955, the entire contents of which are incorporated herein by reference, and in particular from paragraph

[0005] to

[0030] of WO2017 / 123955.

[0125] The crosslinker material may comprise one or more crosslinker material(s). For example, the crosslinker material may comprise one or more crosslinker material(s) operable to crosslink acid-functionality on the acrylic material. For example, the crosslinker material may comprise a carbodiimide material and a hydroxy (alkyl) amide material and / or a hydroxy(alkyl) urea material.

[0126] The crosslinker material may comprise one or more crosslinker material(s) operable to crosslink acid functionality on the acrylic material and one or more further crosslinker material(s) operable to crosslink further functional groups on the acrylic material. For example, the one or more further crosslinker material(s) may be operable to crosslink hydroxy functionality, ethylenically unsaturated functionality, oxirane functionality, thiol functionality and / or amine functionality on the acrylic material. The further crosslinker material may be operable to crosslink hydroxy functionality on the acrylic material.

[0127] The post repair coating composition may comprise: a) a crosslinker material operable to crosslink acid functionality on the acrylic material selected from a carbodiimide material, a hydroxy (alkyl) amide material, such as a p-hydroxy (alkyl) amide material, and / or a hydroxy(alkyl) urea material; and b) a further crosslinker material operable to crosslinker further functional groups on the acrylic material, such as hydroxy functionality on the acrylic material.

[0128] The further crosslinker material may comprise the reaction product of a reaction mixture comprising:(i) a cyclic unsaturated acid anhydride and / or diacid derivative thereof;(ii) an ethylenically unsaturated monomer; and(iii) an alcohol, amine, thiol and / or water, wherein at least a portion of the cyclic unsaturated acid anhydride and / or diacid derivative thereof is reacted with the alcohol, amine, thiol and / or water; and wherein the crosslinker material has an acid number of at least 100 mg KOH / g. Examples of suitable crosslinkers of this type are disclosed in WO 2021 / 195440, the entire contents of which are incorporated herein by reference, and in particular in paragraphs

[0003] and

[0007] to

[0110] of WO 2021 / 195440.

[0129] The further crosslinker material may comprise the reaction product of a reaction mixture comprising:(i) s70% by weight of a cyclic unsaturated acid anhydride and / or diacid derivative thereof by total solid weight of the monomers from which the crosslinker material is formed;(ii) optionally, an ethylenically unsaturated monomer;(iii) and optionally, an alcohol, amine, thiol and / or water, wherein at least a portion of the cyclic unsaturated acid anhydride and / or diacid derivate thereof is reacted with the alcohol, amine, thiol and / or water, when present; and wherein the crosslinker material has an acid number of at least 100 mg KOH / g. Examples of suitable crosslinkers of this type are disclosed in WO 2021 / 195329, the entire contents of which are incorporated herein by reference, and in particular in paragraphs

[0003] and

[0009] to

[0104] of WO 2021 / 195329.

[0130] The post repair coating composition may comprise any suitable amount of the crosslinker material. The post repair coating composition may comprise at least 1 wt%, such as at least 2 wt%, such as at least 3 wt%, such as at least 4 wt%, such as at least 5 wt%, such as at least 6 wt%, such as at least 7 wt%, such as at least 8 wt%, such as at least 9 wt%, such as at least 10 wt% of the crosslinker material based on the total solid weight of the composition. The post repair coating composition may comprise up to 90 wt%, such as up to 80 wt%, such as up to 70 wt%, such as up to 50 wt%, such as up to 40 wt%, such as up to 30 wt%, such as up to 20 wt% of the crosslinker material based on the total solid weight of the composition.

[0131] The post repair coating composition may comprise from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 90 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 80 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 70 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 60 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 50 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 40 wt% of the crosslinker material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 30 wt% of the crosslinker materialbased on the total solid weight of the composition, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 20 wt% of the crosslinker material based on the total solid weight of the composition.

[0132] The post repair coating composition may comprise from 2 to 20 wt% of the crosslinker material based on the total solid weight of the composition.

[0133] The post repair coating composition may comprise from 5 to 15 wt% of the crosslinker material based on the total solid weight of the composition.

[0134] The post repair coating composition may comprise any suitable weight ratio of acrylic material to crosslinker material. The weight ratio of acrylic material to crosslinker material may be from 20:1 to 1 :1, such as from 10:1 to 2:1 , such as from 10:1 to 5:1.

[0135] As mentioned above, the crosslinker material may comprise a carbodiimide material. The post repair coating composition may comprise any suitable amount of the carbodiimide material. The post repair coating composition may comprise at least 1 wt%, such as at least 2 wt%, such as at least 3 wt%, such as at least 4 wt%, such as at least 5 wt%, such as at least 6 wt%, such as at least 7 wt%, such as at least 8 wt%, such as at least 9 wt%, such as at least 10 wt% carbodiimide material based on the total solid weight of the composition. The post repair coating composition may comprise up to 90 wt%, such as up to 80 wt%, such as up to 70 wt%, such as up to 50 wt%, such as up to 40 wt%, such as up to 30 wt%, such as up to 20 wt% carbodiimide material based on the total solid weight of the composition.

[0136] The post repair coating composition may comprise from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 90 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 80 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 70 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 60 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 50 wt% carbodiimide material based on the total solid weight of the composition, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 40 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 30 wt% carbodiimide material based on the total solid weight of the composition, such as from 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt% to 20 wt% carbodiimide material based on the total solid weight of the composition.

[0137] The post repair coating composition may comprise from 2 to 20 wt% carbodiimide material based on the total solid weight of the composition.

[0138] The post repair coating composition may comprise from 5 to 15 wt%, of the carbodiimide material based on the total solid weight of the composition.

[0139] The post repair coating composition may comprise any suitable weight ratio of acrylic material to carbodiimide material. The weight ratio of acrylic material to carbodiimide material may be at least 1 :1 , such as at least 2:1, such as at least 3:1 , such as at least 4:1 , such as at least 5:1 , such as at least 6:1. The weight ratio of acrylic material to carbodiimide material may be from 50:1 to 1 :1 , such as from 50:1 to 2:1, such as from 50 to 5:1 , such as from 40:1 to 5:1 ,such as from 30:1 to 5:1 , such as from 25:1 to 5:1 , such as from 20:1 to 5:1 , such as from 20:1 to 5:1 , such as from 15:1 to 5:1 , such as from 10:1 to 5:1.

[0140] The post repair coating composition may comprise a liquid carrier. The liquid carrier may comprise water and / or one or more organic solvents.

[0141] The liquid carrier may comprise water. When the liquid carrier comprises water, the post repair coating composition may be described as aqueous or an aqueous-based coating composition. The liquid carrier may comprise any suitable amount of water. The liquid carrier may comprise at least 10 wt%, such as at least 15 wt%, such as at least 20 wt%, such as at least 25 wt%, such as at least 30 wt%, such as at least 35 wt%, such as at least 40 wt%, such as at least 45 wt%, such as at least 50 wt%, such as at least 55 wt%, such as at least 60 wt%, such as at least 65 wt%, such as at least 70 wt% water based on the total weight of the liquid carrier. The remainder of the liquid carrier may typically be made up from one or more organic solvent(s), for example.

[0142] The liquid carrier may comprise at least 40 wt% water based on the total weight of the liquid carrier. The remainder of the liquid carrier may typically be made up from one or more organic solvent(s), for example.

[0143] The liquid carrier may comprise a solvent. The liquid carrier may comprise a single solvent or a mixture of solvents.

[0144] The solvent suitably has sufficient volatility to essentially entirely evaporate from the coating composition during the curing process. As a non-limiting example, the curing process may be by heating to a peak metal temperature (PMT) of up to 150 °C.

[0145] Suitable organic solvents include, but are not limited to the following: aliphatic hydrocarbons such as mineral spirits and high flash point naphtha; aromatic hydrocarbons such as benzene; toluene; xylene; solvent naphtha 100, 150, 200; those available from Exxon-Mobil Chemical Company under the SOLVESSO (RTM) trade name; alcohols such as ethanol; n- propanol; isopropanol; and n-butanol; ketones such as acetone; cyclohexanone; methylisobutyl ketone; methyl ethyl ketone; esters such as ethyl acetate; butyl acetate; n-hexyl acetate; RHODIASOLV (RTM) RPDE (a blend of succinic and adipic esters commercially available from Rhodia); glycols such as butyl glycol; glycol ethers such as methoxypropanol; ethylene glycol monomethyl ether; ethylene glycol monobutyl ether and combinations thereof.

[0146] The liquid carrier may comprise any suitable amount of solvent. The liquid carrier may comprise up to 90 wt%, such as up to 85 wt%, such as up to 80 wt%, such as up to 75 wt%, such as up to 70 wt%, such as up to 65 wt%, such as up to 60 wt%, such as up to 55 wt%, such as up to 50 wt%, such as up to 45 wt%, such as up to 40 wt%, such as up to 35 wt%, such as up to 30 wt% solvent based on the total weight of the liquid carrier. The remainder of the liquid carrier may typically be made up from water, for example.

[0147] The liquid carrier may be used in the post repair coating composition in amounts from 5 to 95 wt%, such as from 10 to 90 wt%, such as from 20 to 90 wt%, such as from 30 to 90 wt%, such as from 40 to 90 wt%, such as from 50 to 90 wt%, such as from 60 to 85 wt%, such asfrom 65 to 85 wt%, such as from 65 to 80 wt% based on the total weight of the coating composition.

[0148] The post repair coating compositions may be substantially free of bisphenol A (BPA) and derivatives thereof. The post repair coating compositions may be essentially free or may be completely free of bisphenol A (BPA) and derivatives thereof. Derivatives of bisphenol A include, for example, bisphenol A diglycidyl ether (BADGE). The post repair coating compositions may also be substantially free of bisphenol F (BPF) and derivatives thereof. The post repair coating compositions may be essentially free or may be completely free of bisphenol F (BPF) and derivatives thereof. Derivatives of bisphenol F include, for example, bisphenol F diglycidyl ether (BPFGE). The post repair coating compositions may also be substantially free of bisphenol S (BPS) and derivatives thereof. The post repair coating compositions may be essentially free or may be completely free of bisphenol S (BPS) and derivatives thereof. Derivatives of bisphenol S include, for example, bisphenol S diglycidyl ether (BPSGE). The compounds or derivatives thereof mentioned above may not be added to the composition intentionally but may be present in trace amounts because of unavoidable contamination from the environment. By “substantially free” we mean to refer to compositions containing less than 1000 parts per million (ppm) of any of the compounds or derivatives thereof mentioned above. By “essentially free” we mean to refer to compositions containing less than 100 ppm of any of the compounds or derivatives thereof mentioned above. By “completely free” we mean to refer to compositions containing less than 20 parts per billion (ppb) of any of the compounds or derivatives thereof.

[0149] The post repair coating compositions may be substantially free, essentially free or may be completely free of tin, for example of dialkyltin compounds, including oxides or other derivatives thereof. Examples of dialkyltin compounds include, but are not limited to, dibutyltindilaurate (DBTDL); dioctyltindilaurate; dimethyltin oxide; diethyltin oxide; dipropyltin oxide; dibutyltin oxide (DBTO); dioctyltinoxide (DOTO) or combinations thereof. By “substantially free” we mean to refer to compositions containing less than 1000 parts per million (ppm) of any of the compounds or derivatives thereof mentioned above. By “essentially free” we mean to refer to compositions containing less than 100 ppm of any of the compounds or derivatives thereof mentioned above. By “completely free” we mean to refer to compositions containing less than 20 parts per billion (ppb) of any of the compounds or derivatives thereof.

[0150] The post repair coating compositions may be substantially free, may be essentially free or may be completely free of bromine. By “substantially free” we mean to refer to compositions containing less than 1000 parts per million (ppm) of bromine. By “essentially free” we mean to refer to compositions containing less than 100 ppm of bromine. By “completely free” we mean to refer to compositions containing less than 20 parts per billion (ppb) of bromine.

[0151] The post repair coating compositions may be substantially free, may be essentially free or may be completely free of formaldehyde. By “substantially free” we mean to refer to compositions containing less than 1000 parts per million (ppm) of formaldehyde. By “essentiallyfree” we mean to refer to compositions containing less than 100 ppm of formaldehyde. By “completely free” we mean to refer to compositions containing less than 20 parts per billion (ppb) of formaldehyde. The compositions may comprise 0 wt% of formaldehyde.

[0152] The post repair coating composition may comprise other optional materials well known in the art of formulating coatings, such as colorants, plasticizers, abrasion-resistant particles, antioxidants, hindered amine light stabilizers, UV light absorbers and stabilizers, surfactants, brighteners, defoamers, surface additives, flow control agents, thixotropic agents, fillers, reactive diluents, catalysts, grind vehicles, lubricants, waxes and other customary auxiliaries.

[0153] The post repair coating composition may comprise a colorant (or pigment, which terms may be used interchangeably herein). The colorant may be any suitable colorant.

[0154] As used herein, the term "colorant” means any substance that imparts colour and / or other opacity and / or other visual effect to the composition. The colorant can be added to the coating compositions in any suitable form, such as discrete particles, dispersions, solutions and / or flakes. A single colorant or a mixture of two or more colorants can be used in the coating compositions of the present invention. Suitable colorants are listed in U.S. Patent No. 8,614,286, column 7, line 2 through column 8, line 65, which is incorporated by reference herein. Examples for packaging coating compositions are those approved for food contact, such as titanium dioxide; iron oxides, such as black iron oxide; aluminium paste; aluminium powder such as aluminium flake; carbon black; ultramarine blue; phthalocyanines, such as phthalocyanine blue and phthalocyanine green; chromium oxides, such as chromium green oxide; graphite fibrils; ferried yellow; quindo red; and combinations thereof, and those listed in Article 178.3297 of the Code of Federal Regulations, which is incorporated by reference herein.

[0155] The colorant may comprise an anti-corrosion pigment.

[0156] The post repair coating compositions may be provided in any suitable form. The post repair coating composition may be a one component (“1 K”) or a multi-component composition, such as a two component (“2K”) composition. A 1 K composition will be understood as referring to a composition wherein all the components are maintained in the same container after manufacture, during storage, etc. A 1 K composition can be applied to a substrate and cured by any conventional means, such as by heating, forced air, radiation cure and the like. A 2K, or multi- component, composition will be understood as referring to a composition wherein various components are maintained separately until just prior to application.

[0157] The post repair coating composition may be a two component (“2K”) composition or a multi-component composition, such as a two component (“2K”) composition.

[0158] Thus, the post repair coating composition may be provided as a two-component composition comprising a first component and a second component. The first component may comprise the acrylic material, a liquid carrier and optionally one or more ingredients selected from catalysts, pigments, fillers and other customary auxiliaries (such as any of those defined herein). The second component may comprise the crosslinker material and a liquid carrier. For example, the second component may comprise a carbodiimide material and a liquid carrier.

[0159] When the composition is provided as a multi-part composition, such as a two- component composition, the components, such as first component and second component, are suitably mixed prior to application to a substrate. The components, such as first component and second component, may be mixed at any suitable time prior to application to the substrate, such as up to 1 hour, up to 30 minutes, up to 10 minutes, up to 5 minutes, up to 2 minutes, or up to 1 minute prior to application to a substrate. The components, such as first component and second component, may be mixed immediately prior to application to a substrate. The components, such as first component and second component, may be mixed by any suitable method. Suitable methods will be known to a person skilled in the art and include static and / or dynamic mixing.

[0160] For the avoidance of doubt, when the composition is provided as a multi-component composition, such as a two-component composition, suitable amounts of each material which may be present in the post repair coating composition as defined herein are based on the total composition, i.e., on the amounts present in the coating composition when the two (or more) components are combined to form one coating composition, unless specified otherwise.

[0161] The post repair coating compositions may have any suitable solids content. “Solids content” of a composition as used herein is defined as the total weight of solid materials present in a composition over the total weight of the composition and is defined as a percentage (i.e., solid content = [total solid wt] / [total weight]*100) . The post repair coating composition may have a solids content suitable to allow the composition to be spray applied to a substrate, i.e., to be sprayable. For example, the post repair coating composition may have a solids content from 10 to 30 wt%, such as from 12 to 25 wt%, such as from 15 to 22 wt% based on the total weight the coating composition.

[0162] The post repair coating compositions may be applied to any suitable substrate. The substrate may be formed of metal.

[0163] Suitable metals include, but are not limited to, the following: steel; tinplate; tinplate pretreated with an inorganic protective material, such as chromium (Cr(VI) and / or Cr(lll)), titanium, titanate, zirconium, and aluminium, and / or an organic protective material; tin-free steel (TFS); tin-free steel (TFS) pre-treated with an inorganic protective material, such as chromium (Cr(VI) and / or Cr(lll)), titanium, titanate, zirconium, and aluminium, and / or an organic protective material; galvanised steel, such as for example electro-galvanised steel; aluminium; aluminium alloy; and combinations thereof.

[0164] The metal may be aluminium, aluminium alloy, or combinations thereof.

[0165] Examples of suitable metal substrates include, but are not limited to, food or beverage packaging, and components used to fabricate such packaging or monobloc aerosol cans and / or tubes.

[0166] The substrate may be a food or beverage package or component used to fabricate such packaging. Thus, there is also provided a food or beverage package comprising a surface having a coating on at least a portion thereof, the coating being derived from a post repaircoating composition according to the present invention. The food or beverage packaging may be a can. Examples of cans include, but are not limited to, two-piece cans, three-piece cans and the like. Suitable examples of monobloc aerosol cans and / or tubes include, but are not limited to, deodorant and hair spray containers. Monobloc aerosol cans and / or tubes may be aluminium monobloc aerosol cans and / or tubes.

[0167] The substrate may be a monobloc aerosol can and / or tube.

[0168] The application of various pre-treatments and coatings to packaging is well established. Such treatments and / or coatings, for example, can be used in the case of metal cans, wherein the treatment and / or coating is used to retard or inhibit corrosion, provide a decorative coating, provide ease of handling during the manufacturing process, and the like. Coatings can be applied to the interior of such cans to prevent the contents from contacting the metal of the container. Contact between the metal and a food or beverage, for example, can lead to corrosion of a metal container, which can then contaminate the food or beverage. This is particularly true when the contents of the can are acidic in nature. The coatings applied to the interior of metal cans also help prevent corrosion in the headspace of the cans, which is the area between the fill line of the product and the can lid; corrosion in the headspace is particularly problematic with food products having a high salt content. Coatings can also be applied to the exterior of metal cans.

[0169] The post repair coating compositions can be applied to the interior and / or the exterior of the package. The coating compositions could also be applied as a rim coat to the bottom of the can. The coating compositions can also be applied to caps and / or closures; such application can include, for example, a protective varnish that is applied after formation of the cap / closure, particularly those having a scored seam at the bottom of the cap.

[0170] Metal coils, having wide application in many industries, are also substrates that can be coated according to the present invention. Coil coatings also typically comprise a colorant.

[0171] The substrate may be a post-consumer recycled aluminum substrate.

[0172] The post repair coating composition is suitably applied as a post repair coating. The coating may suitably be applied as a post repair coating for component parts of food and beverage cans. For example, the post repair coating composition may be applied as a repair coating for an easy open end for beverage cans or a full aperture easy open end for food cans. These end components are repair coated, after fabrication, by airless spraying of the post repair coating composition on to the exterior of the score line. Other uses as repair coatings include the coating of seams and welds, such as side seams for which the post repair coating composition may be applied to the area by spraying (airless or air driven) or roller coating. Repair coatings can also include protection of vulnerable areas where corrosion may be likely due to damage, these areas include flanges, rims and bottom rims where the coating may be applied by spraying, roller coating flow or dip coating.

[0173] Thus, the post repair coating compositions may be applied to a score line, a seam, such as a side seam, a weld, a flange, a rim, a bottom rim, and / or any other vulnerable area wherecorrosion may be likely due to damage, of food or beverage packaging, such as a food or beverage can. The post repair coating compositions may be applied to at least a portion of an internal and / or external surface of said food and / or beverage can. For example, when the coating compositions are applied to a food and / or beverage can, the post repair coating compositions may be applied to at least a portion of an internal surface of said food and / or beverage can.

[0174] The post repair coating compositions may be applied to the substrate by any suitable method. Methods of applying the post repair coating compositions will be well known to a person skilled in the art. Suitable application methods include, but are not limited to the following: electrocoating such as electrodeposition; spraying; electrostatic spraying; dipping; rolling; brushing; and the like. The post repair coating compositions may be applied to the substrate by spraying. Thus, the post repair coating compositions may be spray compositions. For the avoidance of doubt, by the term ‘spray composition’ and like terms as used herein is meant, unless specified otherwise, that the coating composition is suitable to be applied to a substrate by spraying, i.e. is sprayable.

[0175] According to a third aspect of the present invention there is provided a method of repairing a score line on a food or beverage package, such as a food or beverage can, the method comprising applying to the score line a post repair coating composition according to the first aspect.

[0176] The method may further comprise the step of curing the post repair spray coating composition, such as by applying heat to a peak metal temperature (PMT) of up to 150°C.

[0177] The peak metal temperature (PMT) as used herein refers to the temperature of the substrate, i.e. the metal surface of a food or beverage package, such as a food or beverage can.

[0178] As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word "about", even if the term does not expressly appear. Also, the recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1 , 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges subsumed therein.

[0179] Singular encompasses plural and vice versa. For example, although reference is made herein to “a” crosslinking material, “a” carbodiimide material, “an” acrylic material, “an” acid group, “an” alcohol group, and the like, one or more of each of these and any other components can be used. As used herein, the term "polymer" refers to oligomers and both homopolymers and copolymers, and the prefix "poly" refers to two or more.

[0180] The terms "comprising", "comprises" and "comprised of” as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. Additionally, although the present invention has been described in terms of “comprising”, the coating compositions detailed herein may also be described as “consisting essentially of” or “consisting of”.

[0181] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

[0182] The term "alk” or “alkyl", as used herein unless otherwise defined, relates to saturated hydrocarbon radicals being straight, branched, cyclic or polycyclic moieties or combinations thereof and contain 1 to 20 carbon atoms, such as 1 to 10 carbon atoms, such as 1 to 8 carbon atoms, such as 1 to 6 carbon atoms, or even 1 to 4 carbon atoms. These radicals may be optionally substituted with a chloro, bromo, iodo, cyano, nitro, OR19, OC(O)R20, C(O)R21, C(O)OR22, NR23R24, C(O)NR25R26, SR27, C(O)SR27, C(S)NR25R26, aryl or Het, wherein R19to R27each independently represent hydrogen, aryl or alkyl, and / or be interrupted by oxygen or sulphur atoms, or by silano or dialkylsiloxane groups. Examples of such radicals may be independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tertbutyl, 2-methylbutyl, pentyl, iso-amyl, hexyl, cyclohexyl, 3-methylpentyl, octyl and the like. The term “alkylene”, as used herein, relates to a bivalent radical alkyl group as defined above. For example, an alkyl group such as methyl which would be represented as -CH3, becomes methylene, -CH2-, when represented as an alkylene. Other alkylene groups should be understood accordingly.

[0183] The term “alkenyl”, as used herein, relates to hydrocarbon radicals having, such as up to 4, double bonds, being straight, branched, cyclic or polycyclic moieties or combinations thereof and containing from 2 to 18 carbon atoms, such as 2 to 10 carbon atoms, such as from 2 to 8 carbon atoms, such as 2 to 6 carbon atoms, or even 2 to 4 carbon atoms. These radicals may be optionally substituted with a hydroxyl, chloro, bromo, iodo, cyano, nitro, OR19, OC(O)R20, C(O)R21, C(O)OR22, NR23R24, C(O)NR25R26, SR27, C(O)SR27, C(S)NR25R26, or aryl, wherein R19to R27each independently represent hydrogen, aryl or alkyl, and / or be interrupted by oxygen or sulphur atoms, or by silano or dialkylsiloxane groups. Examples of such radicals may be independently selected from alkenyl groups include vinyl, allyl, isopropenyl, pentenyl, hexenyl, heptenyl, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, 1 -propenyl, 2-butenyl, 2- methyl-2-butenyl, isoprenyl, farnesyl, geranyl, geranylgeranyl and the like. The term “alkenylene”, as used herein, relates to a bivalent radical alkenyl group as defined above. For example, an alkenyl group such as ethenyl which would be represented as -CH=CH2, becomes ethenylene, -CH=CH-, when represented as an alkenylene. Other alkenylene groups should be understood accordingly.

[0184] The term "alkynyl", as used herein, relates to hydrocarbon radicals having, such as up to 4, triple bonds, being straight, branched, cyclic or polycyclic moieties or combinations thereof and having from 2 to 18 carbon atoms, such as 2 to 10 carbon atoms, such as from 2 to 8 carbon atoms, such as from 2 to 6 carbon atoms, or even from 2 to 4 carbon atoms. These radicals may be optionally substituted with a hydroxy, chloro, bromo, iodo, cyano, nitro, OR19, OC(O)R20, C(O)R21, C(O)OR22, NR23R24, C(O)NR25R26, SR27, C(O)SR27, C(S)NR25R26, or aryl, wherein R19to R27each independently represent hydrogen, aryl or lower alkyl, and / or be interrupted by oxygen or sulphur atoms, or by silano or dialkylsiloxane groups. Examples of such radicals may be independently selected from alkynyl radicals include ethynyl, propynyl, propargyl, butynyl, pentynyl, hexynyl and the like. The term “alkynylene”, as used herein, relates to a bivalent radical alkynyl group as defined above. For example, an alkynyl group such as ethynyl which would be represented as -C=CH, becomes ethynylene, -C=C-, when represented as an alkynylene. Other alkynylene groups should be understood accordingly.

[0185] The term “aryl” as used herein, relates to an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes any monocyclic, bicyclic or polycyclic carbon ring of up to 7 members in each ring, wherein a ring is aromatic. These radicals may be optionally substituted with a hydroxy, chloro, bromo, iodo, cyano, nitro, OR19, OC(O)R20, C(O)R21, C(O)OR22, NR23R24, C(O)NR25R26, SR27, C(O)SR27, C(S)NR25R26, or aryl, wherein R19to R27each independently represent hydrogen, aryl or lower alkyl, and / or be interrupted by oxygen or sulphur atoms, or by silano or dialkylsilcon groups. Examples of such radicals may be independently selected from phenyl, p-tolyl, 4-methoxyphenyl, 4-(tert-butoxy)phenyl, 3- methyl-4-methoxyphenyl, 4-fluorophenyl, 4-chlorophenyl, 3-nitrophenyl, 3-aminophenyl, 3- acetamidophenyl, 4-acetamidophenyl, 2-methyl-3-acetamidophenyl, 2-methyl-3-aminophenyl, 3- methyl-4-aminophenyl, 2-amino-3-methylphenyl, 2,4-dimethyl-3-aminophenyl, 4-hydroxyphenyl, 3-methyl-4-hydroxyphenyl, 1 -naphthyl, 2-naphthyl, 3-amino-1 -naphthyl, 2-methyl-3-amino-1 - naphthyl, 6-amino-2-naphthyl, 4,6-dimethoxy-2-naphthyl, tetrahydronaphthyl, indanyl, biphenyl, phenanthryl, anthryl or acenaphthyl and the like. The term “arylene”, as used herein, relates to a bivalent radical aryl group as defined above. For example, an aryl group such as phenyl which would be represented as -Ph, becomes phenylene, -Ph-, when represented as an arylene. Other arylene groups should be understood accordingly.

[0186] For the avoidance of doubt, the reference to alkyl, alkenyl, alkynyl, aryl or aralkyl in composite groups herein should be interpreted accordingly, for example the reference to alkyl in aminoalkyl or alk in alkoxyl should be interpreted as alk or alkyl above etc.

[0187] All of the features contained herein may be combined with any of the above aspects in any combination.

[0188] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following examples.EXAMPLES

[0189] The following examples are intended to illustrate the invention and should not be construed as limiting the invention in any way.Acrylic Example 1

[0190] Acrylic example 1, which has an acid value below 50 mg KOH / g, was prepared according to the formulation in Table 1 and by the following process method. All amounts are given in parts by weight (pbw) unless otherwise specified.Table 1 - Formulation of Acrylic Example 1* = tert-Butyl peroxy-3,5,5-trimethylhexanoate** = the amine used to neutralize the polymerProcess Method

[0191] The polymerization was carried out using a reaction vessel equipped with heating, stirring, a reflux condenser, and a nitrogen blanket. Addition of monomers and free radical initiator were linked to the reaction vessel by pumps which could be used to control the addition rate. Item 1 was added to the reaction vessel and heated to reflux (115-118°C). Whilst the vessel was heating to reflux, item 3 components were mixed in the initiator tank and item 2 components were mixed in the monomer tank. With the contents of the reactor refluxing at a temperature of 115-118°C, the contents of the monomer tank and 18.98% of the contents of the initiator tank were simultaneously added to the reactor at a constant rate over a period of 90minutes. After the addition was completed, the contents of the reactor were held at reflux (118- 121 °C) for 30 minutes. Then item 5 was added to the reactor from the monomer tank as a line wash. Item 4 was added to the monomer tank and mixed in preparation for the second monomer feed. After holding the reactor contents at reflux for 30 minutes, the contents of the monomer tank and the remaining 81.02% of the contents of the initiator tank were added the reactor over 180 minutes. Once the second monomer I initiator feed was complete, the reactor was held at reflux (118-124°C) for 60 minutes. The monomer and initiator tanks were rinsed with items 6 and 7 respectfully. After the hold, the reactor temperature set point was reduced to 82°C. Item 8 was added when the reactor contents were cooled below 110°C. Item 9 was added over 30 minutes when the reactor mixture was cooled below 100°C.

[0192] The resultant acrylic polymer had the following characteristics:Solids content 38.86% (400°F, 10 minutes, 0.5 g sample, 1 g diluent)Viscosity 4,256 centipoise (spindle #7, 20rpm @ 25°C)Acid Value (solids) 47.34Molecular weight (Mn) 5,397Molecular weight (Mw) 76,766Comparative Acrylic Example 1

[0193] Comparative acrylic example 1 , which has an acid value above 50 mg KOH / g, was prepared according to the formulation in Table 2 and by the following process method. All amounts are given in parts by weight (pbw) unless otherwise specified.Table 2 - Formulation of Comparative Acrylic Example 1Process Method

[0194] The polymerization was carried out using a reaction vessel equipped with heating, stirring, a reflux condenser, and a nitrogen blanket. Addition of monomers and free radical initiator were linked to the reaction vessel by pumps which could be used to control the addition rate. Item 1 was added to the reaction vessel and heated to reflux (129°C). Whilst the vessel was heating to reflux, item 3 components were mixed in the initiator tank and item 2 components were mixed in the monomer tank. With the contents of the reactor refluxing at a temperature of 129°C, the contents of the monomer tank and the initiator tank were simultaneously added to the reactor at a constant rate over a period of 240 minutes. After the addition was completed, the contents of the reactor were held at reflux (130-132°C) for 120 minutes. During the hold, the monomer and initiator tanks were rinsed with items 4 and 5 respectively. After the hold, the reactor contents were cooled.

[0195] The resultant acrylic polymer had the following characteristics:Solids content 70.89% (204°C, 10 minutes, 0.5 g sample, 1 g diluent)Viscosity 10,730 centipoise (spindle #7, 10 rpm @ 25°C)Acid Value (solids) 74.14 Molecular Weight (Mn) 5,839 Molecular Weight (Mw) 18,401Preparation of coating compositions

[0196] Coating compositions were prepared according to the formulations in Tables 3-. All amounts are given in parts by weight (pbw) unless otherwise specified. First, a solution of theacrylic materials was prepared according to the formulations in Table 3. Then, coating compositions were prepared as two-component compositions (comprise of Part A and Part B), which were stored separately as stable components, according to the formulations in Tables 4A and 4B. Part A was prepared by sequentially adding items 1 -7, as set out in Table 4A, to a vessel stirred with a high-speed mixer at 25°C. Mixing was continued for 10 minutes after the addition of all items was complete. Part B was prepared by sequentially adding items 1 -3, as set out in Table 4B, to a vessel stirred with a high-speed mixer at 25°C. Mixing was continued for 10 minutes after the addition of items was complete.

[0197] The two components, Parts A and B, were then mixed in in the amounts outlined below in Table 4C, and by the following method, prior to application of the coating compositions to the substrate. Part B to was added to Part A in a mixing vessel which was stirred with a high-speed mixing blade at 500-1000 rpm at a temperature around 25°C. Mixing was continued for 10 minutes after the addition of both parts was complete. After mixing, each of the coating compositions were stored at a temperature around 25°C. They remained in a usable state for around 10 hours.Table 3 - Formulation of Acrylic SolutionsTable 4A - Formulation of First Component of the Two-Part Compositions (Part A)Silicone wetting agent, commercially available from BYK-Chemie GmbH Tinopal NFW 10 Liq commercially available from BASFPolyether-based defoamer, commercially available from BYK-Chemie GmbHTable 4B - Formulation of Second Component of the Two-Part Compositions (Part B)4= Carbodiimide crosslinker, 100% solids, commercially available from Stahl Holdings B.V.5= Carbodiimide crosslinker, 50% solids, supplied in propylene glycol methyl ether acetate, commercially available from Stahl Holdings B.V.Table 4C - Formulation of Coating CompositionsCoating application and drying

[0198] The coating compositions were applied to pre-coated tinplate full aperture easy open ends (FAEOEs), having a score line, by brush coating or by spraying as follows.

[0199] Brush application: the coating compositions were applied to a tinplate full aperture easy open end (as routinely used as a component of food or beverage cans) pre-coated with clear, gold or white pigmented lacquer with print markings. The coating compositions were applied with a paint brush in a stripe of 10-20 mm as a preliminary procedure to cover the score line on the easy open end for the screening of dry film resistance. After application, the easy open ends were dried for 120 seconds in an oven at a temperature of 120°C to 150°C (to achieve a peak metal temperature (PMT) from 110°C to 140°C) as outlined in Tables 6 and 7 below, to produce a cured film.

[0200] Spray application: for a more in-depth investigation, and to align with industrial application, the coating compositions were applied to a tinplate full aperture easy open end precoated with clear, gold or white pigmented lacquer with print markings with an airless spray gun in a stripe 5 - 25 mm wide over the score line on the easy open end. After application, the easy open ends were dried for 120 seconds in an oven at a temperature of 120°C to 150°C (toachieve a peak metal temperature (PMT) from 110 °C and 140 °C) as outlined in Tables 6 and 7 below, to produce a cured film.Details of methods for testing coatings

[0201] The performance of the coatings as a repair / protective layer over the score line was evaluated using the following tests.

[0202] Corrosion resistance (brush coated FAEOEs): the industrial process for processing or sterilisation of cans containing various food fillings often uses water which is at higher pH (pH 9 -10). Corrosion resistance to a solution of NaaCOs in water is known to be an efficient method to test the ability of coatings to withstand such industrial processes.

[0203] The brush coated ends were sterilised in an autoclave for 90 minutes at 121 °C in i) water and ii) a 0.05% solution of NaaCOs in water. The ends were completely immersed in the liquid in each case. The score line was examined for defects under an optical microscope. The appearance of the score line was rated between 0 and 5. Grade 0 corresponds to perfect film appearance with no visible metal corrosion. Grade 5 corresponds to complete attack of the film across the whole of the score line.

[0204] Corrosion resistance (spray coated FAEOEs): industrial processing or sterilisation of cans containing various food fillings requires sufficient coating resistance against high pressure and high temperature conditions. Corrosion resistance to a CuSO4 solution is known to be an efficient method to test the ability of coatings to withstand such industrial processes.

[0205] The spray coated ends were fully or half immersed in a CuSO4 solution (10 % w / w CuSO4, 10% w / w HCI (37%), 80 % w / w deionized water) for five minutes. After 5 minutes, the ends were flushed with water and dried. The score line was examined for defects under an optical microscope. The appearance of the score line was rated between 0 and 5. Grade 0 corresponds to perfect film appearance with no visible corrosion or copper deposition. Grade 5 corresponds to complete attack of the film across the whole of the score line.

[0206] The spray coated ends were also tested for corrosion resistance against water and a 0.05% solution of Na2COs in water using the same method, and same evaluation method, as described above for the brush applied coatings. The ends were either fully immersed or half immersed in the solutions.

[0207] Liquid phase test results correspond to ends that were fully immersed in the relevant solution. Vapor phase test results correspond to ends that were half immersed in the relevant solution.

[0208] Results are shown in Tables 5, 6 and 7.ResultsTable 5 - Test results for brush applied coating compositionsTable 6 - Test results for spray applied coating compositions

[0209] The results show that the inventive coating, which includes an acrylic material having an acid value below 50 mg KOH / g, has improved corrosion resistance compared to those of the comparative examples, which include an acrylic material having an acid value above 50 mg KOH / g. The improvement is observed for both the brush applied and spray applied coating compositions, and in all tests.

[0210] Thus, it can be seen from the examples that a coating composition in accordance with the present invention provides a post repair coating that i) can be cured at a lower curing temperature than would typically be expected (180-220°C), ii) have a workable pot life of at least 8 hours (a pot life lower than this would typically be deemed unacceptable), Hi) can be applied using airless spray equipment, and iv) provides sufficient corrosion resistance to the exposed metal score line to which it has been applied (and improved corrosion resistance compared to the coatings of the comparative examples).

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

Claims

CLAIMS1. A post repair coating composition for a food or beverage package, such as a food or beverage can, the coating composition comprising: a) an acrylic material comprising acid-functionality, wherein the acrylic material has an acid value below 50 mg KOH / g; and b) a crosslinker material, the crosslinker material being formed from reactants that are substantially free of formaldehyde.

2. The post repair coating composition according to claim 1 , wherein the crosslinker material is formed from reactants that do not include formaldehyde.

3. The post repair coating composition according to any one of claims 1 or 2, wherein the crosslinker material comprises a hydroxy (alkyl) amide material, such as a p-hydroxy (alkyl) amide material, a hydroxy(alkyl) urea material and / or a carbodiimide material.

4. The post repair coating composition according to claim 3, wherein the crosslinker material comprises a carbodiimide material, for example a polycarbodiimide resin.

5. The post repair coating composition according to any one of claims 1 -4, wherein the coating composition comprises a liquid carrier comprising water6. The post repair coating composition according to any one of claims 1 -5, wherein the coating composition is a two-component system, wherein the two-component system comprises a first component comprising the acrylic material (a) and a second component comprising the crosslinker material (b), for example wherein the first component comprises the acrylic material and a liquid carrier and the second component comprises the crosslinker material and a liquid carrier.

7. The post repair coating composition according to any one of claims 1 -6, wherein the acrylic material comprises a solution polymerised acrylic material and / or an emulsion polymerised acrylic material.

8. The post repair coating composition according to any one of claims 1 -7, wherein the acrylic material has an acid value of at least 5 mg KOH / g.

9. The post repair coating composition according to any one of claims 1 -7, wherein the acrylic material has an acid value from 20 to 45 mg KOH / g, such as from 30 to 45 mg KOH / g, or even from 35 to 45 mg KOH / g.

10. The post repair coating composition according to any one of claims 1 -8, wherein the acrylic material is formed from a reaction mixture, the reaction mixture comprising one or more acrylic monomer(s), for example selected from alkyl (alk)acrylate, alkyl (meth)acrylate, and / or (alk)acrylic acid.

11. The post repair coating composition according to claim 10, wherein at least one of the acrylic monomers comprises a functional group, such as a hydroxy group; and / or wherein at least one of the acrylic monomers is a multi-ethylenically unsaturated monomer.

12. The post repair coating composition according to any one of claims 10 or 11 , wherein the reaction mixture is substantially free of styrene.

13. The post repair coating composition according to any one of claims 1-12, wherein the acid functionality of the acrylic material is at least partially neutralised with a suitable neutraliser.

14. The post repair coating composition according to any one of claims 1-13, wherein the coating composition comprises at least 50 wt%, such as at least 60 wt%, such as at least 70 wt%, such as at least 75 wt%, such as at least 80 wt% of the acrylic material based on the total solid weight of the composition.

15. The post repair coating composition according to any one of claims 1-14, wherein the coating composition comprises from 2 to 20 wt%, such as from 5 to 15 wt%, of the crosslinker material based on the total solid weight of the composition.

16. The post repair coating composition according to any one of claims 1-15, wherein the weight ratio of acrylic material to crosslinker material is from 20:1 to 1 :1 , such as from 10:1 to 2:1, such as from 10:1 to 5:1.

17. The post repair coating composition according to any one of claims 1-16, wherein the composition is substantially free of bisphenol A (BPA), bisphenol F (BPF) and derivatives thereof; and / or wherein the composition is substantially free of formaldehyde.

18. The post repair coating composition according to any one of claims 1-17, wherein the composition is a spray composition.

19. A food or beverage package, such as a food or beverage can, comprising a surface having a coating on at least a portion thereof, the coating being derived from a post repair coating composition according to any one of claims 1 -18.

20. A method of repairing a score line on a food or beverage package, such as a food or beverage can, the method comprising applying to the score line a post repair coating composition according to any one of claims 1-18.

21. The method according to claim 20, wherein the method further comprises the step of curing the post repair coating composition, such as by applying heat to a peak metal temperature (PMT) of up to 150°C.

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