Aqueous coating compositions based on polyesters containing DMPOA

Abstract

A novel curable polyester comprising the reaction product of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) and dimethylolpropionic acid is disclosed. The curable polyester is particularly useful in waterborne coating compositions. Such waterborne coating compositions provide a good balance of desirable coating properties for metal packaging applications.

Description

Technical Field

[0001] This invention relates to polyester compositions comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) and dimethylolpropionic acid (2,2-bis(hydroxymethyl)propionic acid) (DMPOA) as internal stabilizers in aqueous formulations. Aqueous coating compositions prepared from such polyesters provide a desirable balance of coating properties for metal packaging applications. Background of the Invention

[0003] Metal containers are commonly used for food and beverage packaging. Containers are typically made of steel or aluminum. Prolonged contact between the metal and the filled product can lead to corrosion of the container. To prevent direct contact between the filled product and the metal, a coating is usually applied to the inside of food and beverage cans. For effectiveness, such coatings must possess certain properties required to protect the integrity of both the packaged product and the metal container, such as adhesion, corrosion resistance, chemical resistance, flexibility, stain resistance, and hydrolytic stability. Furthermore, the coating must be able to withstand the processing conditions during can manufacturing and food sterilization. Coatings based on a combination of epoxy and phenolic resins are known to provide a good balance of the required properties and are the most widely used. Some industrial sectors are moving away from food contact polymers made from bisphenol A (BPA) (the basic structural unit of epoxy resin). Therefore, there is a need for BPA-free coatings for the inner can coatings.

[0004] Polyester resins (due to their comparable properties, such as flexibility and adhesion) are of particular interest in the coating industry as alternatives to epoxy resins. 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (TMCD) is an alicyclic compound that can be used as a diol component in the manufacture of polyesters. Thermoplastics based on TMCD polyesters exhibit improved impact resistance due to the unique structure of TMCD. TMCD can also provide improved hydrolytic stability to polyesters due to the functionality of its secondary hydroxyl groups. Both of these properties are highly desirable in thermosetting coatings.

[0005] There is interest in using TMCD polyester-based coatings as an alternative to epoxy resins for internal tank coating applications. Previous efforts have involved coating systems based on high-Tg, medium-molecular-weight TMCD polyesters with slight crosslinking to withstand the processing conditions during tank manufacturing. However, such systems have been found to be insufficient in some desired properties, such as corrosion resistance, boiling resistance, and resistance to microcracks (crazing). Higher crosslinking can lead to improved coating properties, such as corrosion resistance, acid resistance, stain resistance, and boiling resistance. However, such coatings tend to have lower flexibility, which can adversely affect resistance to microcracks and bending ability during processing.

[0006] Therefore, it is desirable to create a coating system that provides a good balance of properties required for the intended application. These improvements are particularly desirable for waterborne polyester systems.

[0007] The object of this invention is to provide a polyester composition for waterborne coating applications. Specifically, this invention provides a polyester composition wherein the polyester comprises TMCD as a diol component and dimethylolpropionic acid (2,2-bis(hydroxymethyl)propionic acid) (DMPOA) as an internal stabilizer for waterborne formulations. DMPOA would be an ideal candidate as a functional monomer for introducing additional acid functionality into resin systems, eliminating the need for conventional acrylic modification; however, producing high molecular weight resins without producing gels or undesirable high dispersion is challenging. Unexpectedly, we have developed a resin containing high levels of DMPOA and a high molecular weight, exhibiting a desirable dispersion index.

[0008] This type of coating system is unique in that the polyester portion can simultaneously provide high molecular weight, effective hydroxyl functionality for crosslinking, and sufficient carboxyl groups for water dispersibility. By utilizing this unique characteristic, the aqueous compositions of the present invention can be easily tuned to obtain desirable coating properties that are otherwise unattainable. For example, polyesters used for metal packaging coatings are typically designed to have hydroxyl values ​​below 30 KOH / mg and acid values ​​below 5 mg KOH / g to obtain the high molecular weight required for can manufacturing. However, the lack of sufficient carboxyl end groups for neutralization to provide water dispersibility poses an obstacle to aqueous formulations. To overcome this obstacle, a high level of acrylic acid is required to provide water dispersibility. However, the overall performance of the coating is thus affected. Therefore, a technological breakthrough is highly anticipated to break this deadlock. Invention Overview

[0010] In one embodiment, the present invention provides an aqueous coating composition comprising:

[0011] a. Polyesters, which are the products of the following reaction:

[0012] i. 30 to 60 mol% of 2,2,4,4-tetramethyl,1,3-cyclobutanediol (TMCD) based on the total moles of i-iv.

[0013] ii. 20 to 69 mol% of diols other than TMCD, based on the total molar number of i-iv.

[0014] iii. Triols in amounts of 0 to 8 mol% based on the total moles of i-iv.

[0015] iv. 15 to 30 mol% of dimethylolpropionic acid (DMPOA) based on the total moles of i-iv.

[0016] v. 0 to 20 mol% of an α,β-unsaturated diacid or anhydride based on the total number of moles of v-vii.

[0017] vi. 60 to 97 mol% of aromatic diacids based on the total molar number of v-vii, and

[0018] vii. Aliphatic diacids in amounts of 0 to 20 mol% based on the total moles of v-vii, and

[0019] b. Crosslinking agent,

[0020] The polyester has an acid value of 30 to 100 mg KOH / g, a hydroxyl value of 6 to 30 mg KOH / g, a number-average molecular weight of 4,000 to 25,000 g / mole, and a weight-average molecular weight of 13,000 to 200,000 g / mole.

[0021] Detailed description

[0022] definition

[0023] In this specification and the appended claims, reference will be made to many terms, which should be defined as having the following meanings.

[0024] "Alkyl" refers to an aliphatic hydrocarbon. Alkyl groups can specify the number of carbon atoms, for example (C... 1-5 Alkyl groups. Unless otherwise stated, alkyl groups may be unbranched or branched. In one embodiment, the alkyl group is branched. In another embodiment, the alkyl group is unbranched. Non-limiting examples of alkanes include methane, ethane, propane, isopropyl (i.e., branched propyl), butyl, etc.

[0025] "Alcohol" refers to a chemical substance containing one or more hydroxyl groups.

[0026] "Aldehyde" refers to a chemical substance containing one or more -C(O)H groups.

[0027] A value may be expressed as “approximately” or “roughly” for a given number. Similarly, a range may be expressed herein as “approximately” for a particular value and / or to “approximately” for another particular value. When expressing such a range, the other side includes from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the prior term “approximately,” it is to be understood that the particular value forms the other side.

[0028] The terms “a species”, “a kind”, and “the” used in this article refer to one or more species.

[0029] 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 may be used on its own, or may be used in any combination of two or more of the listed items. For example, if a composition is described as containing components A, B and / or C, the composition may contain A alone; B alone; C alone; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B and C.

[0030] The terms “contains,” “includes,” and “include” used in this document are open transitional terms used to transition from a subject listed before the term to one or more elements listed after the term, wherein the one or more elements listed after the transitional term are not necessarily the only elements constituting the subject.

[0031] The terms “having,” “possessing,” and “include” as used in this document have the same open-ended meaning as “containing,” “include,” and “include” provided above.

[0032] The terms “including,” “comprising,” and “including” as used in this document have the same open-ended meaning as “containing,” “including,” and “included” provided above.

[0033] The word “selected from” as used in this article may be used with “or” or “and”. For example, “Y selected from A, B and C” means that Y can be A, B or C alone. Or, “Y selected from A, B or C” means that Y can be A, B or C alone; or a combination of A and B, A and C, B and C, or A, B and C.

[0034] An unexpected finding is disclosed herein: aqueous coating compositions based on polyesters comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) as a diol component and dimethylolpropionic acid (DMPOA) as an internal stabilizer can provide desirable coating properties for a variety of applications, particularly in metal packaging. Unexpectedly, the resins disclosed herein contain high levels of DMPOA and a high molecular weight, exhibiting a desirable dispersion index.

[0035] In one embodiment, the present invention provides an aqueous coating composition comprising:

[0036] a. Polyesters, which are the products of the following reaction:

[0037] i. 30 to 60 mol% of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) based on the total moles of i-iv.

[0038] ii. 20 to 69 mol% of diols other than TMCD, based on the total molar number of i-iv.

[0039] iii. Triols in amounts of 0 to 8 mol% based on the total moles of i-iv.

[0040] iv. 15 to 30 mol% of dimethylolpropionic acid (DMPOA) based on the total moles of i-iv.

[0041] v. 0 to 20 mol% of an α,β-unsaturated diacid or anhydride based on the total number of moles of v-vii.

[0042] vi. 60 to 97 mol% of aromatic diacids based on the total molar number of v-vii, and

[0043] vii. Aliphatic diacids in amounts of 0 to 20 mol% based on the total moles of v-vii, and

[0044] b. Crosslinking agent,

[0045] The polyester has an acid value of 30 to 100 mg KOH / g, a hydroxyl value of 6 to 30 mg KOH / g, a number-average molecular weight of 4,000 to 25,000 g / mole, and a weight-average molecular weight of 13,000 to 200,000 g / mole.

[0046] In some embodiments of the present invention, the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) (i) is 35-55 mol%, the amount of diol (ii) other than TMCD is 30 to 62 mol%, the amount of triol (iii) is 0 to 5 mol%, the amount of DMPOA (iv) is 15-25 mol%, the amount of α,β-unsaturated diacid or anhydride (v) is 0 to 18 mol%, the amount of aromatic diacid (vi) is 67 to 95 mol%, and the amount of aliphatic diacid (vii) is 0 to 15 mol.

[0047] In other embodiments, the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) (i) is 40-50 mol%, the amount of diol (ii) other than TMCD is 40 to 55 mol%, the amount of triol (iii) is 0 to 3 mol%, the amount of DMPOA (iv) is 15-20 mol%, the amount of α,β-unsaturated diacid or anhydride (v) is 0 to 15 mol%, the amount of aromatic diacid (vi) is 5 to 93 mol%, and the amount of aliphatic diacid (vii) is 0 to 10 mol.

[0048] In other respects, the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) is 30-60, 32-58, 35-55, 37-53, 40-50, or 42-48 mol, based on the total number of moles of i-iii.

[0049] In other respects, based on the total number of moles of i-iv, the amount of the diol other than TMCD is 20-69, 25-67, 30-62, 35-60, or 40-55 moles.

[0050] In other respects, based on the total number of moles of i-iv, the amount of the triol is 0-8, 0-7, 0-6, 0-5, 0-4, 0-3, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8 mol%.

[0051] In other respects, the amount of DMPOA is 15-30, 15-25, 15-20, 20-25, 20-30, or 25-30 moles, based on the total number of moles of i-iv.

[0052] In other respects, based on the total number of moles of v-vii, the amount of the α,β-unsaturated diacid or anhydride is 1-20, 2-19, 3-18, 4-17, 5-15, 6-15, 7-15, 8-15, 9-15, 10-15, 1-3, 1-5, 1-8, 1-10, 2-5, 3-7, or 5-10 mol%.

[0053] In other respects, the amount of the aromatic diacid is 60-97, 64-96, 67-95, or 75-93 mol, based on the total number of moles of v-vii.

[0054] In other respects, based on the total number of moles of v-vii, the amount of the aliphatic diacid is 0-20, 0-18, 0-15, 0-10, 0-5, 5-25, 5-20, 5-15, 5-10, 10-20, 10-15, or 5-20 moles.

[0055] Examples of diols (ii) other than TMCD include 1,4-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,2-cyclohexanediethanol, 1,6-hexanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypentanoyl hydroxypentyl ester, 2-butyl-2-ethyl-1,3-propanediol, and mixtures thereof. In some embodiments, the diol (ii) is selected from 1,4-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,6-hexanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, and mixtures thereof.

[0056] It should be noted that dimethylolpropionic acid (DMPOA) is not included in this description as a diol, despite having two hydroxyl groups.

[0057] Examples of triols include 1,1,1-trimethylolpropane, 1,1,1-trimethylolethane, glycerol, and mixtures thereof. Preferably, the triol is 1,1,1-trimethylolpropane.

[0058] Examples of α,β-unsaturated diacids or anhydrides (v) include maleic acid or its anhydride, crotonic acid or its anhydride, itaconic acid or its anhydride, citraconic acid or its anhydride, mesoconic acid, phenylmaleic acid or its anhydride, tert-butylmaleic acid or its anhydride, and mixtures thereof. Preferably, the α,β-unsaturated diacid or anhydride (iv) is selected from one or more of maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, and itaconic acid. It should be noted that the aforementioned diacids include their monoesters and diesters, such as dimethyl maleate and dimethyl fumarate.

[0059] Examples of the aromatic diacids (vi) include isophthalic acid and its esters, such as dimethyl isophthalate, and terephthalic acid and its esters, such as dimethyl terephthalate.

[0060] The aliphatic diacid (vii) includes C 4- C 12 Dicarboxylic acids and their esters. These aliphatic diacids (vii) do not include α,β-unsaturated diacids or anhydrides specified above as (v). Examples of aliphatic diacids include succinic acid, adipic acid, sebacic acid, dodecanoic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their methyl esters; and (hydrogenated) dimer acids (C... 36 Desiredly, when using longer-chain diacids (>C) 10 When these ratios are small, such as 1-5, 1-4, 1-3, or 1-2 mol%, respectively, the aliphatic diacid is selected from one or more of succinic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid. Preferably, the aliphatic diacid is sebacic acid, adipic acid, or a mixture thereof.

[0061] The polyester has a glass transition temperature (Tg) of 40-110°C, 40-100°C, 40-90°C, 40-80°C, 45-100°C, 50-100°C, 55-100°C, 60-100°C, 65-100°C, 45-90°C, 50-90°C, 55-90°C, 60-90°C, 65-90°C, 50-80°C, 55-80°C, or 60-80°C.

[0062] The polyester has an acid value of 30-100, 40-90, or 50-80 mg KOH / g.

[0063] The polyester has a hydroxyl value of 6-30, 6-28, 6-25, 8-25, 10-25, 12-25, 14-25, 8-23, 10-23, 12-23, 14-23, 10-20, 12-20, 14-20, 16-20, 10-18, 12-18, 14-18, 10-16, or 12-16 mgKOH / g.

[0064] The polyester has a number average molecular weight of 4,000-25,000, 5,000-25,000, 5,000-20,000, 5,000-15,000, 5,000-13,000, 5,000-10,000, 6,000-15,000, 7,000-15,000, 7,000-13,000, or 7,000-10,000 g / mole; and a number average molecular weight of 13,000-200,000, 14,000 g / mole. Weight-average molecular weights of 0-150,000, 15,000-150,000, 20,000-140,000, 25,000-130,000, 30,000-110,000, 23,000-140,000, 28,000-120,000, 15,000-20,000, 15,000-30,000, 15,000-40,000, or 15,000-50,000 g / mole.

[0065] The polyester is synthesized in the presence of a catalyst. Examples of suitable catalysts include those based on titanium, tin, gallium, zinc, antimony, cobalt, manganese, germanium, alkali metals (especially lithium and sodium), alkaline earth metal compounds, aluminum compounds, combinations of aluminum compounds with lithium hydroxide or sodium hydroxide, and mixtures thereof. In one embodiment, the catalyst is based on titanium or tin.

[0066] Examples of suitable titanium compounds include 2-ethylhexyl titanium oxide (IV) (e.g.) TOT), (triethanolamine) isopropoxide titanium (IV) (e.g.) TE), tetraisopropyl titanate, bis(acetylacetonyl)diisopropyl titanate and tetrabutyl titanate (e.g.) Examples of suitable tin compounds include butyltin tri-2-ethylhexanoate, butylstannic acid, stannous oxalate, and dibutyltin oxide.

[0067] In a further embodiment, the present invention provides an aqueous dispersion comprising:

[0068] a) The polyester of the present invention,

[0069] b) Neutralizing agent, and

[0070] c) Water.

[0071] Neutralizing agents can be amines or inorganic bases. Typical amines include ammonia, trimethylamine, diethylamine, monoethanolamine, monoisopropanolamine, morpholine, ethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N-methyldiethanolamine, etc.

[0072] Typical inorganic bases include bases derived from alkali metals and alkaline earth metals such as sodium, potassium, magnesium, and calcium, and other alkaline metal compounds. Suitable bases from the first class of bases that can be used in this invention include, but are not limited to, sodium oxide, potassium oxide, magnesium oxide, calcium oxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, calcium carbonate, magnesium bicarbonate, alkali metal borate compounds and their hydrates, sodium phosphate, potassium dihydrogen phosphate, and sodium pyrophosphate.

[0073] The aqueous dispersion of the present invention may further comprise an organic co-solvent. Suitable co-solvents include ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diacetone alcohol, and other water-miscible solvents.

[0074] The aqueous dispersion of polyester is preferably stable. Stability is defined as the absence of polymer flocculation or phase separation (15 to 80% by weight of solids) in the aqueous dispersion after shelf storage at 20 to 30°C for at least three months.

[0075] Specific polyesters can be isolated purely; however, for typical material handling purposes, it is desirable to prepare dispersions or solutions of the polyesters. Such dispersions or solutions comprise 10 to 50% by weight of liquid, which contains 0 to 90% by weight of water and 0 to 100% by weight of a suitable oxygen-containing organic solvent such as alcohols, ketones, esters, and ethers, preferably low molecular weight alcohols such as C1 to C2 alcohols. 10 Alcohols, such as ethanol, n-propanol, isopropanol, and isobutanol. Such dispersions can be used as coating compositions or as pre-dispersions to prepare coating compositions.

[0076] The coating composition of the present invention comprises (A) about 50 to 90% by weight of the aforementioned polyester based on the total weight of the polyester and crosslinking agent, (B) about 30 to 70% by weight of water based on the total weight of the coating composition, (C) about 0 to 10% by weight of a suitable organic solvent based on the total weight of the coating composition, and (D) about 10 to 50% by weight of a crosslinking agent based on the total weight of the polyester and crosslinking agent. As understood in the art, the exact components and properties of the components required for any given coating application can vary, and therefore, routine experiments may be necessary to determine the optional components and their proportions for a given application and desired properties.

[0077] In another embodiment, based on the total weight of (a) and (b), the coating composition of the present invention comprises 50-90% by weight of the polyester (a) and 10-50% by weight of the crosslinking agent (b). In some embodiments, based on the total weight of (a) and (b), the polyester polyol (a) is 55-85, 60-80, 65-85, 65-80, 65-75, 70-90, 70-85, 70-80, 75-85, 80-90, or 80-85% by weight; and the crosslinking agent (b) is 15-45, 20-40, 15-35, 20-35, 25-35, 10-30, 15-30, 20-30, 15-25, 10-20, or 15-20% by weight.

[0078] The crosslinking agent (b) is one or more crosslinking agents selected from isocyanates, amino resins, and phenolic resins, or mixtures thereof. Preferably, the crosslinking agent is an isocyanate, an amino resin, or a mixture thereof.

[0079] The isocyanate crosslinking agent suitable for this invention can be a capped or uncapped isocyanate type. Examples of suitable isocyanate crosslinking agents include, but are not limited to, 1,6-hexamethylene diisocyanate, methylene bis(4-cyclohexyl isocyanate), and isophorone diisocyanate. Preferably, the isocyanate crosslinking agent is isophorone diisocyanate (IPDI) or can be used as... BL 2078 / 2 is an IPDI from COVESTRO. Available from COVESTRO. 3100 is a hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI); it is particularly suitable for aqueous formulations.

[0080] In addition to isocyanates, the crosslinking agent (b) can also be an amino resin. The amino resin crosslinking agent (or crosslinking reagent) can be a melamine-formaldehyde type crosslinking agent or a benzoguanamine-formaldehyde type crosslinking agent, i.e., a crosslinking agent having multiple -N(CH2OR3)2 functional groups, wherein R... 3 It is a C1-C4 alkyl group, preferably methyl.

[0081] In yet another embodiment, based on the total weight of the crosslinking agent, the crosslinking agent (b) is a mixture of 20-80% by weight of an amino resin and 80-20% by weight of an isocyanate.

[0082] Typically, the amino crosslinking agent can be selected from compounds of the following formula, where R 3 Independently C1-C4 alkyl:

[0083]

[0084] Amino-containing crosslinking agents are preferably hexamethoxymethyl melamine, hexabutoxymethyl melamine, tetramethoxymethyl benzoguanamine, tetrabutoxymethyl benzoguanamine, tetramethoxymethylurea, and mixed butoxy / methoxy substituted melamines. Suitable commercially available amino resins include Maprenal BF 987 (a butylated benzoguanamine-formaldehyde resin available from Ineos), Cymel 1123 (a highly methylated / ethylated benzoguanamine-formaldehyde resin available from Allnex), Cymel 1158 (an amino-functionalized butylated melamine-formaldehyde resin available from Allnex), Cymel 325 (a methylated, highly iminoized melamine resin available from Allnex), and other benzoguanamine-formaldehyde and melamine-formaldehyde resins.

[0085] In one embodiment, the crosslinking agent (b) is a mixture of Maprenal BF 987 and Cymel 325.

[0086] In addition to isocyanates and amino crosslinking agents, the crosslinking agent (b) may also be a phenolic resin; preferably, the phenolic resin is a methyl phenolic resin.

[0087] The methyl phenolic resin contains unsubstituted phenolic and / or meta-substituted phenolic residues. These specific methyl phenolic resins exhibit good reactivity with the polyester polyol (a). Desiredly, the amount of methyl phenolic resin is at least 50% by weight, or greater than 60% by weight, or greater than 70% by weight, or greater than 80% by weight, or greater than 90% by weight, based on the total weight of all crosslinking agent compounds in the resin.

[0088] The methyl phenolic resin present in the crosslinking composition contains a hydroxymethyl group on the phenolic ring. Phenolic resins with hydroxymethyl functionality are referred to as methyl phenolic resins. As is known in the art, the hydroxymethyl group (-CH2OH) can be etherified with an alcohol and exist as -CH2OR, where R is a C1-C8 alkyl group, to improve resin properties such as storage stability and compatibility. For descriptive purposes, the term "hydroxymethyl" as used herein includes both -CH2OH and -CH2OR, and the unsubstituted hydroxymethyl group is CH2OH. The hydroxymethyl group (-CH2OH or -CH2OR) is an end group attached to the methyl phenolic resin. The hydroxymethyl group is formed during the synthesis of the methyl phenolic resin and can further react with another molecule to form an ether or methylene bond, thereby producing a macromolecule.

[0089] Phenolic resins contain residues of unsubstituted or meta-substituted phenols. When a primary phenolic resin is manufactured starting with a phenol or meta-substituted phenol, both para and ortho positions can be used for bridging reactions to form a branched network, wherein the final hydroxymethyl terminal group on the resin is para or ortho relative to the phenolic hydroxyl group. To manufacture a primary phenolic resin, a phenolic composition is used as the starting material. The phenolic composition contains unsubstituted and / or meta-substituted phenols. The amount of unsubstituted, meta-substituted, or a combination of both present in the phenolic composition used as a reactant to manufacture the primary phenolic resin is at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 98% by weight, based on the weight of the phenolic composition used as the starting material.

[0090] The phenolic composition reacts with a reactive compound such as an aldehyde in an aldehyde:phenol molar ratio greater than 1:1, or at least 1.05:1, or at least 1.1:1, or at least 1.2:1, or at least 1.25:1, or at least 1.3:1, or at least 1.35:1, or at least 1.4:1, or at least 1.45:1, or at least 1.5:1, or at least 1.55:1, or at least 1.6:1, or at least 1.65:1, or at least 1.7:1, or at least 1.75:1, or at least 1.8:1, or at least 1.85:1, or at least 1.9:1, or at least 1.95:1, or at least 2:1 (using aldehyde as an example). There is no upper limit to the amount of aldehyde, and it can be up to 30:1, but is typically at most 5:1, or at most 4:1, or at most 3:1, or at most 2.5:1. Typically, the aldehyde:phenol ratio is at least 1.2:1 or greater, or 1.4:1 or greater, or 1.5:1 or greater, and usually at most 3:1. These ratios also apply to the ratio of aldehyde to unsubstituted or meta-substituted phenols.

[0091] The methyl phenolic resin may contain an average of at least 0.3, or at least 0.4, or at least 0.45, or at least 0.5, or at least 0.6, or at least 0.8, or at least 0.9 hydroxymethyl groups per phenolic hydroxyl group, and "hydroxymethyl" includes -CH2OH and -CH2OR.

[0092] Through phenols and the general formula (RCHO) n Phenolic resins are obtained by the condensation of aldehydes, wherein R is hydrogen or a hydrocarbon group having 1 to 8 carbon atoms and n is 1, 2, or 3. Examples include formaldehyde, metaldehyde, acetaldehyde, glyoxal, propionaldehyde, furfural, or benzaldehyde. Preferably, phenolic resins are the reaction products of phenol and formaldehyde.

[0093] (b) At least a portion of the crosslinking agent comprises a first-order phenolic resin type phenolic resin prepared by reacting an unsubstituted phenol or a meta-substituted phenol, or a combination thereof, with an aldehyde. The unsubstituted phenol is phenol (C6H5OH). Examples of meta-substituted phenols include m-cresol, m-ethylphenol, m-propylphenol, m-butylphenol, m-octylphenol, m-alkylphenol, m-phenylphenol, m-alkoxyphenol, 3,5-xylenol, 3,5-diethylphenol, 3,5-dibutylphenol, 3,5-dialkylphenol, 3,5-dicyclohexylphenol, 3,5-dimethoxyphenol, 3-alkyl-5-alkoxyphenol, etc.

[0094] Although other substituted phenolic compounds may be used in combination with the unsubstituted or meta-substituted phenols to manufacture phenolic resins, it is desirable that at least 50%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 98%, or at least 100% of the phenolic compounds used to manufacture methyl phenolic resins are unsubstituted or meta-substituted phenols.

[0095] In one aspect, the methyl phenolic resin used in this invention comprises meta-substituted phenolic residues.

[0096] Examples of suitable commercially available phenolic resins include, but are not limited to, those available from Allnex. PR516 / 60B (based on cresol and formaldehyde), also available from Allnex PR 371 / 70B (based on unsubstituted phenol and formaldehyde) and CURAPHEN 40-856B60 (based on m-cresol, p-cresol and formaldehyde), available from Bitrez.

[0097] Phenolic resins are desirablely thermosetting. Phenolic resins are desirablely not manufactured by adding bisphenol A, F, or S (collectively referred to as "BPA").

[0098] Amorphous phenolic resins are desirablely alcohol-soluble. Amorphous phenolic resins can be liquid at 25°C. Amorphous phenolic resins can have a weight-average molecular weight of 200 to 2000, typically 300 to 1000, or 400 to 800, or 500 to 600.

[0099] In some embodiments, the crosslinking agent (b) is a mixture of CURAPHEN 40-856 B60, which is available from Bitrez, and end-capped isophorone diisocyanate (IPDI).

[0100] In another embodiment, based on the total weight of the crosslinking agent, the crosslinking agent (b) is a mixture of 10-90% by weight of a methyl phenolic resin and 90-10% by weight of an isocyanate.

[0101] Any thermosetting composition of the present invention may further comprise one or more crosslinking catalysts. Representative crosslinking catalysts include carboxylic acids, sulfonic acids, tertiary amines, tertiary phosphines, tin compounds, or combinations thereof. Some specific examples of crosslinking catalysts include p-toluenesulfonic acid, phosphoric acid, and NACURE, sold by King Industries. TM Catalysts 155, 5076, 1051 and XC-296B, BYK 450, 470, methyltoluenesulfonylimide, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid and dinonylnaphthalenedisulfonic acid, benzoic acid, triphenylphosphine, dibutyltin dilaurate and dibutyltin diacetate.

[0102] The crosslinking catalyst used in this invention may depend on the type of crosslinking agent used in the coating composition. For example, the crosslinking agent may comprise an amino crosslinking agent, and the crosslinking catalyst may comprise p-toluenesulfonic acid, phosphoric acid, uncapped and capped dodecylbenzenesulfonic acid (hereinafter abbreviated as "DDBSA"), dinonylnaphthalenesulfonic acid (hereinafter abbreviated as "DNNSA"), and dinonylnaphthalenedisulfonic acid (hereinafter abbreviated as "DNNDSA"). Some of these catalysts are commercially available, such as NACURE. TM 155, 5076, 1051, 5225 and XC-296B (available from King Industries), BYK-CATALYSTS TM (Available from BYK-Chemie USA) and CYCAT TM Catalyst (available from Cytec Surface Specialties). The coating compositions of this invention may contain one or more isocyanate crosslinking catalysts, such as FASCAT. TM 4202 (Dibutyltin dilaurate), FASCAT TM 4200 (dibutyltin diacetate, both available from Arkema), DABCO TM T-12 (available from Air Products) and K-KAT TM 348, 4205, 5218, XC-6212 TM Non-tin catalysts (available from King Industries) and tertiary amines.

[0103] Based on the total weight of any of the aforementioned curable polyester resin and crosslinking agent compositions, the coating composition may contain an acid or base catalyst in an amount of 0.1 to 2% by weight.

[0104] As another embodiment, the present invention provides an aqueous coating composition comprising:

[0105] a) The polyester of the present invention,

[0106] b) Neutralizing agent,

[0107] c) Water, and

[0108] d) Crosslinking agents selected from amino resins, isocyanate resins and phenolic resins.

[0109] In another embodiment, the coating composition of the present invention further comprises one or more organic solvents. Suitable organic solvents include xylene, ketones (e.g., methylpentyl ketone), 2-butoxyethanol, ethyl 3-ethoxypropionate, toluene, butanol, cyclopentanone, cyclohexanone, ethyl acetate, butyl acetate, Aromatic 100, and Aromatic 150 (all available from ExxonMobil), and other volatile inert solvents commonly used in industrial baking (i.e., thermosetting) enamels, mineral oil, naphtha, toluene, acetone, methyl ethyl ketone, methyl isopentyl ketone, isobutyl acetate, tert-butyl acetate, n-propyl acetate, isopropyl acetate, methyl acetate, ethanol, n-propanol, isopropanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, trimethylpentanediol monoisobutyrate, ethylene glycol monooctyl ether, diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (available under the trademark TEXANOL) TM Purchased from Eastman Chemical Company), or a combination thereof.

[0110] After formulation, the coating composition can be applied to a substrate or article. Thus, another aspect of the invention is a molded or shaped article coated with the coating composition of the invention. The substrate can be any common substrate, such as aluminum, tin, steel, or galvanized sheet. The coating composition can be applied to the substrate using techniques known in the art, for example by spraying, drawing-down, rolling, etc., with a wet coating of about 0.1 to about 4 mils (1 mil = 25 μm), or 0.5 to 3, or 0.5 to 2, or 0.5 to 1 mil. The coating can be cured at a temperature of about 50°C to about 230°C for a period of about 5 seconds to about 90 minutes and then allowed to cool. Examples of coated articles include metal cans for food and beverages, the interior of which is coated with the coating composition of the invention.

[0111] Therefore, the present invention further provides an article having at least a portion coated with the coating composition of the present invention. Example

[0112] The invention can be further illustrated by the following embodiments, but it should be understood that, unless otherwise specifically stated, these embodiments are included for illustrative purposes only and are not intended to limit the scope of the invention.

[0113] Coating test methods:

[0114] Substrate, coating test plate preparation, film weight

[0115] Chromium (Cr) with a thickness of 0.125 mm 3+ Aluminum sheets treated with [treatment method] are used as the substrate. The substrate is coated by pouring a wet film using a winding bar, producing 10 to 11 grams per m. 2 The dry film weight was determined. The cast plates were cured horizontally one at a time in an oven. The Despatch forced-air oven was preheated to a set temperature of 350°C. The coated plates were placed in the oven for a 28-second baking cycle to allow the coating to bake at a peak metallographic temperature (PMT) of 240°C for 10 seconds. At the end of the baking cycle, the plates were removed from the oven and allowed to cool to ambient temperature. A Sencon SI9600 coating thickness gauge was used to determine the dry film weight of the applied coating.

[0116] Reverse impact test

[0117] Cut a 3″ wide x 8″ long measurement specimen from the coated plate. On the back (uncoated side) of the plate, draw three test squares evenly distributed in the center of the plate using a template. Mark the center point of each square to indicate where the impact point will be. Align the center point of the square below the 2lb dart and release the dart from a height of 11cm. After completing all the plates, apply a piece of tape vertically across the impact zone on the coated side of the plate. Packaging Tape 610 (ensure firm contact before timely and rapid removal). When removing the tape, adhere it to the back of a board near the impact area from which the tape was removed. Use a paper towel saturated with a 5% copper sulfate solution to smear the impact area to help highlight the location of adhesion loss and expose the substrate. Evaluate the adhesion loss of the boards using a rating of 1-5, with those showing a 5 indicating the best performance.

[0118] Methyl ethyl ketone (MEK) bi-friction

[0119] MEK solvent resistance was measured using a MEK abrasion tester (Gardco MEK abrasion tester AB-410103EN with a 1 kg specimen). This test is similar to ASTM D7835. The MEK solvent resistance report is the number of double abrasion cycles the coated plate can withstand before the coating removal process begins. For example, one reciprocating motion constitutes one double abrasion cycle. A maximum of 100 double abrasion cycles is set as the upper limit for each evaluation.

[0120] Sterilization resistance test

[0121] Coated specimens measuring 2.5″ wide x 4″ long were cut from the coating plate. The specimens were then placed in 16-ounce wide-mouth Le Parfait glass jars, half filled with food simulants, with one half of the specimen above the food simulant liquid and the other half submerged in it. Two different food simulants were evaluated:

[0122] • Ctric acid: 1% lactic acid, 99% deionized water

[0123] • Deionized (DI) water

[0124] The appropriately sealed jars were placed in a Priorclave Model PNA / QCS / EH150 autoclave at 121°C for 30 minutes. Once the cooking process was complete, the autoclave was depressurized to ambient conditions. After the sterilization cycle was completed, the glass jars containing the samples were removed from the autoclave. The samples were removed from the jars, washed in water, and blotted dry with paper towels. The cooking performance was rated on a scale of 0 (worst) to 5 (best) by visual inspection. For each food simulant, the cooking performance was rated by (1) blush in the gas phase, (2) blush in the liquid phase, (3) roughness in the gas phase, (4) roughness in the liquid phase, and (5) cross-cut adhesion in the liquid phase (following ASTM D 3359). The total cooking performance was reported as total cooking % calculated as follows:

[0125]

[0126] Each cooking rating in this experiment is the average rating from two repeated trials.

[0127] Example 1: Synthesis of DMPOA-containing polyesters (resins UM-5 and UM-15) using a DMPOA monomer segmentation method

[0128] The polyester synthesis process consists of two stages. In the first stage, monomers, except for maleic anhydride (MA) and DMPOA, are added and reacted. In the second stage, maleic anhydride (MA) and varying amounts of DMPOA monomer are added to achieve a final DMPOA molar content of 5% or 15% for the diol monomer.

[0129] Isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), 1,4-cyclohexanediethanol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), and 0-10 wt% ShellSol A150ND (an aromatic solvent available from Shell Chemicals) were added to the reactor, which was then fully assembled. After assembling the reactor and blanketing the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using a set output controlled by an automated system. Once the reaction mixture had sufficient fluidity, stirring was initiated to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was raised to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour, and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for stage 1 was reached. The reaction mixture was held overnight at 150°C, and any additional A150ND required to reach the desired ~10 wt% was added at 150°C, followed by reheating to the reaction temperature. After reaching the target acid value for stage 1, the reaction mixture was cooled to 190°C, and 4-methoxyphenol (MeHQ, 1 wt% based on MA) was added and stirred for 15 minutes. Next, maleic anhydride (MA) was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C for 1 hour and then cooled to 190°C. DMPOA was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then maintained at 230°C, with the acid value monitored every 30–60 minutes until the desired acid value was reached. The reaction mixture was poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight percentage. The solution was filtered through a ~250 μm paint filter before use for formulation and application testing. It should be noted that for laboratory reactors, the glycol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The glycol:acid ratio was also manipulated to achieve the desired molecular weight, OHN, and AN. An example of a basic charge table is provided in Table 1 below.

[0130] Table 1

[0131]

[0132]

[0133] Table 2

[0134]

[0135] Table 3

[0136] Resin# Tg, ℃ Mn Mw PDI AN OHN UM-5 73 11192 35030 3.13 12 12 UM-15 73 5137 19501 3.80 38 25

[0137] Example 2: Synthesis of a DMPOA-containing saturated polyester (resin SM-20) using a DMPOA monomer-based staged method.

[0138] The saturated polyester synthesis process consists of two stages. In the first stage, monomers, except for DMPOA, are added and reacted. In the second stage, DMPOA monomer is added to achieve a final DMPOA molar content of 20% for the diol monomer.

[0139] Isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), 1,4-cyclohexanediethanol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPDiol), and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A1 50ND solvent was added to a Dean Stark separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using a set output controlled by an automated system. Once the reaction mixture had sufficient fluidity, stirring was initiated to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was increased to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for Stage 1 was reached. An overnight holding temperature of 150°C was used, and any additional A150ND required to reach the desired ~10 wt% was added at 150°C, followed by reheating to the reaction temperature. Once the target acid value for Stage 1 was reached, the reaction mixture was cooled to 190°C, and 4-methoxyphenol (MeHQ, 1 wt% based on MA) was added and stirred for 15 minutes. Next, maleic anhydride (MA) was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C for 1 hour and then cooled to 190°C. DMPOA was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C, and the acid value was monitored every 30–60 minutes until the final desired acid value was reached. The reaction mixture is poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight percentage. The solution is filtered through a ~250 μm varnish filter before use for formulation and application testing. It should be noted that for laboratory reactors, the glycol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The glycol:acid ratio is also manipulated to achieve the desired molecular weight, OHN, and AN. An example of a basic charge table is provided in Table 4 below.

[0140] Table 4

[0141]

[0142]

[0143] Table 5

[0144]

[0145] Table 6

[0146] Resin# Tg, ℃ Mn Mw PDI AN OHN SM-20 69 2911 9852 3.38 57 32

[0147] Example 3: Synthesis of DMPOA-containing polyesters (resins UO-2, UO-) using a staged method with DMPOA / CHDA oligomers. 5. UO-10 and UO-15)

[0148] The polyester synthesis process consists of two steps. In the first step, an oligomer of DMPOA / CHDA is produced. In the second step, stage 2, different amounts of DMPOA / CHDA oligomer are added to achieve a final DMPOA molar content of 2%, 5%, 10%, or 15% for the diol monomer.

[0149] In the first step, oligomers of DMPOA / CHDA were produced using a resin reactor apparatus controlled by automated control software. Resin was produced in a 3.5–4.5 molar scale using a 2-liter reactor with a top stirrer and a partial condenser topped with a full condenser and a Dean Stark separator. 2,2-bis(hydroxymethyl)propionic acid (DMPOA), 1,4-cyclohexanedicarboxylic acid (CHDA), and 0–10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMCorganometallix Inc.) was added via a sampling port. The temperature was raised to 200°C over a 2-hour period. Once the reaction mixture had sufficient fluidity, stirring was initiated to promote uniform heating of the mixture. The reaction was held at 200°C for 0.5 hours and then heated to 210°C. The reaction was held at 210°C for 0.5 hours and then heated to 220°C. The reaction was held at 220°C for 0.5 hours and then heated to 230°C. The reaction was held at 230°C for 0.5 hours. The reaction mixture was poured into a metal pan for crushing. An example of a basic charge table is provided in Table 7 below.

[0150] Table 7

[0151]

[0152]

[0153] In the second step, isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), 1,4-cyclohexanediethanol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark water separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using the set output controlled by the automated system. Once the reaction mixture had sufficient fluidity, stirring was started to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was raised to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for Stage 1 was reached. An overnight holding temperature of 150°C was used, and any additional A150ND required to reach the desired ~10 wt% was added at 150°C, followed by reheating to the reaction temperature. Once the target acid value for Stage 1 was reached, the reaction mixture was cooled to 190°C, and 4-methoxyphenol (MeHQ, 1 wt% based on MA) was added and stirred for 15 minutes. Next, maleic anhydride (MA) was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C for 1 hour and then cooled to 190°C. The oligomer of DMPOA / CHDA prepared in Step 1 was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then maintained at 230°C, with the acid value monitored every 30–60 minutes until the desired final acid value was reached. The reaction mixture was poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight percentage. The solution was filtered through a ~250 μm varnish filter before use for formulation and application testing. It should be noted that for laboratory reactors, the glycol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The glycol:acid ratio was also manipulated to achieve the desired molecular weight, OHN, and AN. The amount of DMPOA / CHDA oligomer to be added in the second step was calculated based on the final target resin composition in the second step and the oligomer composition and solids content in the first step. An example of a basic charge table is provided in Table 8 below.

[0154] Table 8

[0155]

[0156]

[0157] Table 9

[0158]

[0159] Table 10

[0160] Resin# Tg, ℃ Mn Mw PDI AN OHN UO-2 66 8560 34554 4.04 6 14 UO-5 63 8071 25798 3.20 15 14 UO-10 75 4007 11954 2.98 30 15 UO-15 78 4318 13959 3.23 45 20

[0161] Example 4: Synthesis of DMPOA-containing saturated polyester (resin SO-) using a staged method with DMPOA / CHDA oligomers 20)

[0162] The saturated polyester synthesis process consists of two steps. In the first step, an oligomer of DMPOA / CHDA is produced. In the second step, the DMPOA / CHDA oligomer is added to achieve a final DMPOA molar content of 20% for the diol monomer.

[0163] In the first step, the oligomer of DMPOA / CHDA was manufactured using the same procedure as that used in Example 3.

[0164] In the second step, isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), 1,4-cyclohexanediethanol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark water separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using the set output controlled by the automated system. Once the reaction mixture had sufficient fluidity, stirring was started to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was raised to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for Stage 1 was reached. An overnight holding temperature of 150°C was used, and any additional A150ND required to achieve the desired ~10% by weight was added at 150°C, followed by reheating to the reaction temperature. Once the target acid value for Stage 1 was reached, the reaction mixture was cooled to 190°C, and the oligomer of DMPOA / CHDA prepared in Step 1 was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C, and the acid value was monitored every 30–60 minutes until the final desired acid value was reached. The reaction mixture was poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight. Before use in formulation and application testing, the solution is filtered through a ~250 μm paint filter. It should be noted that for laboratory reactors, the diol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The diol:acid ratio is also manipulated to achieve the desired molecular weight, OHN, and AN. The amount of DMPOA / CHDA oligomer to be added in the second step is calculated based on the final target resin composition in the second step and the oligomer composition and solids content in the first step. An example of a basic charge table is provided in Table 11 below.

[0165] Table 11

[0166]

[0167]

[0168] Table 12

[0169]

[0170] Table 13

[0171] Resin# Tg, ℃ Mn Mw PDI AN OHN SM-20 69 2911 9852 3.38 57 32

[0172] Comparative Example 5: Synthesis of DMPOA-containing polyesters (resins SC-15 and UC-) using DMPOA without a staged process 20)

[0173] The DMPOA monomer is added in advance along with other monomers.

[0174] Isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), 1,4-cyclohexanediethanol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), DMPOA, and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark water separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using the set output controlled by the automated system. Once the reaction mixture was sufficiently fluid, stirring was initiated to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was increased to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 230°C at a rate of 0.3°C / min. The reaction was then maintained at 230°C, and samples were taken every 1–2 hours after clarification until the desired acid value was reached. However, the reaction mixture gelled after heating at 230°C for approximately 3 hours. An example of a basic charge table is provided in Table 14 below.

[0175] Table 14

[0176]

[0177]

[0178] Table 15

[0179]

[0180] Table 16

[0181]

[0182] Example 6: Synthesis of DMPOA-containing polyester (resin UO-) using a staged method with DMPOA / adipic acid (AA) oligomers AA-5)

[0183] The polyester synthesis process consists of two steps. In the first step, an oligomer of DMPOA / AA is produced. In the second step, stage 2, a specific amount of DMPOA / AA oligomer is added to achieve a final DMPOA molar content of 5% for the diol monomer.

[0184] In the first step, oligomers of DMPOA / AA are produced using a resin reactor apparatus controlled by automated control software. Resin is produced in a 3.5–4.5 molar scale using a 2-liter reactor with a top stirrer and a partial condenser topped with a full condenser and a Dean Stark separator. 2,2-Bis(hydroxymethyl)propionic acid (DMPOA), adipic acid (AA), and 0–10 wt% A150ND are added to the reactor, which is then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMCorganometallix Inc.) is added via a sampling port. The temperature is raised to 200°C over a 2-hour period. Once the reaction mixture has sufficient fluidity, stirring is initiated to promote uniform heating of the mixture. The reaction is held at 200°C for 0.5 hours and then heated to 210°C. The reaction is held at 210°C for 0.5 hours and then heated to 220°C. The reaction was held at 220°C for 0.5 hours, and then heated to 230°C. The reaction was held at 230°C for 0.5 hours. The reaction mixture was poured into a metal pan for crushing. An example of a basic charge table is provided in Table 17 below.

[0185] Table 17

[0186]

[0187]

[0188] In the second step, isophthalic acid (IPA), adipic acid (AA), 1,4-cyclohexanediol (CHDM), 2,2,4,4-tetramethylcyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark water separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using the set output controlled by the automated system. Once the reaction mixture had sufficient fluidity, stirring was started to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was increased to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for Stage 1 was reached. An overnight holding temperature of 150°C was used, and any additional A150ND required to reach the desired ~10 wt% was added at 150°C, followed by reheating to the reaction temperature. Once the target acid value for Stage 1 was reached, the reaction mixture was cooled to 190°C, and 4-methoxyphenol (MeHQ, 1 wt% based on MA) was added and stirred for 15 minutes. Next, maleic anhydride (MA) was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C for 1 hour and then cooled to 190°C. The oligomer of DMPOA / AA prepared in Step 1 was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then maintained at 230°C, with the acid value monitored every 30–60 minutes until the desired final acid value was reached. The reaction mixture was poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight percentage. The solution was filtered through a ~250 μm varnish filter before use for formulation and application testing. It should be noted that for laboratory reactors, the glycol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The glycol:acid ratio was also manipulated to achieve the desired molecular weight, OHN, and AN. An example of a basic charge table is provided in Table 18 below.

[0189] Table 18

[0190]

[0191] Table 19

[0192]

[0193] Table 20

[0194] Resin# Tg, ℃ Mn Mw AN OHN UO-AA-5 41 7155 42672 11 17

[0195] Example 7: Staged synthesis of DMPOA-containing compounds using DMPOA / dimethyl terephthalate (DMT) oligomers Polyester (Resin UO-DMT-5)

[0196] The polyester synthesis process consists of two steps. In the first step, an oligomer of DMPOA / DMT is produced. In the second step, stage 2, a specific amount of DMPOA / DMT oligomer is added to achieve a final DMPOA molar content of 5% for the diol monomer.

[0197] In the first step, oligomers of DMPOA / DMT are produced using a resin reactor apparatus controlled by automated control software. Resin is produced in a 3.5–4.5 molar scale using a 2-liter reactor with a top stirrer and a partial condenser topped with a full condenser and a Dean Stark separator. 2,2-Bis(hydroxymethyl)propionic acid (DMPOA), dimethyl terephthalate (DMT), and 0–10 wt% A150ND are added to the reactor, which is then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMCorganometallix Inc.) is added via a sampling port. The temperature is raised to 200°C over a 2-hour period. Once the reaction mixture has sufficient fluidity, stirring is initiated to promote uniform heating of the mixture. The reaction is held at 200°C for 0.5 hours and then heated to 210°C. The reaction is held at 210°C for 0.5 hours and then heated to 220°C. The reaction was held at 220°C for 0.5 hours and then heated to 230°C. The reaction was held at 230°C for 0.5 hours. The reaction mixture was poured into a metal pan for crushing. An example of a basic charge table is provided in Table 21 below.

[0198] Table 21

[0199]

[0200] In the second step, isophthalic acid (IPA), dimethyl terephthalate (DMT), 1,4-cyclohexanediol (CHDM), 2,2,4,4-tetramethyl-cyclobutanediol (TMCD), 2-methyl-1,3-propanediol (MPdiol), and 0-10 wt% A150ND were added to the reactor, which was then fully assembled. After assembling the reactor and covering the reaction with nitrogen, Fascat 4102 (tris(2-ethylhexanoic acid) monobutyltin, available from PMC Organometallix Inc.) was added via a sampling port. Additional A150ND solvent was added to the Dean Stark water separator to maintain a solvent level of ~10 wt% in the reactor. The reaction mixture was heated from room temperature to 150°C without stirring using the set output controlled by the automated system. Once the reaction mixture had sufficient fluidity, stirring was started to promote uniform heating of the mixture. At 150°C, the heating control was switched to automatic control, and the temperature was increased to 200°C over a 3-hour period. The reaction was held at 200°C for 1 hour and then heated to 240°C at a rate of 0.3°C / min. The reaction was then held at 240°C, and samples were taken every 1–2 hours after clarification until the desired acid value for Stage 1 was reached. An overnight holding temperature of 150°C was used, and any additional A150ND required to reach the desired ~10 wt% was added at 150°C, followed by reheating to the reaction temperature. Once the target acid value for Stage 1 was reached, the reaction mixture was cooled to 190°C, and 4-methoxyphenol (MeHQ, 1 wt% based on MA) was added and stirred for 15 minutes. Next, maleic anhydride (MA) was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then held at 230°C for 1 hour and then cooled to 190°C. The oligomer of DMPOA / DMT prepared in Step 1 was added to the reaction mixture and heated to 230°C at 1.5°C / min. The reaction was then maintained at 230°C, with the acid value monitored every 30–60 minutes until the desired acid value was reached. The reaction mixture was poured into a metal pan for crushing or further diluted with Dowanol DPM glycol ether (DPM, available from Dow Inc.) to achieve the target 60% solids by weight percentage. The solution was filtered through a ~250 μm varnish filter before use for formulation and application testing. It should be noted that for laboratory reactors, the glycol excess is determined empirically and may vary depending on the partial condenser and reactor design used. The glycol:acid ratio was also manipulated to achieve the desired molecular weight, OHN, and AN. An example of a basic charge table is provided in Table 22 below.

[0201] Table 22

[0202]

[0203]

[0204] Table 23

[0205]

[0206] Table 24

[0207] Resin# Tg, ℃ Mn Mw AN OHN UO-DMT-5 70 3252 13924 4 30

[0208] Example 8: Characterization of resin properties

[0209] The glass transition temperature (Tg) was determined using a Q2000 differential scanning calorimeter (DSC) from TA Instruments, New Castle, DE, US, at a scan rate of 20 °C / min. Number-average molecular weight (Mn) and weight-average molecular weight (Mw) were determined by gel permeation chromatography (GPC) using polystyrene equivalent molecular weight and THF or 95 / 5CH2Cl2 / HFIP solvent. Acid values ​​were measured using a procedure based on ASTM D7253-1, entitled “Standard Test Method for Polyurethane Raw Materials: Determination of Acidity as Acid Number for Polyether Polyols,” and hydroxyl values ​​were measured using a procedure based on ASTM E222-1, entitled “Standard Test Methods for Hydroxyl Groups Using Acetic Anhydride.”

[0210] Example 9: Preparation of aqueous dispersions of polyester

[0211] Each polyester prepared in Examples 1-7 was placed in a 500 mL three-necked round-bottom flask and heated to 80 °C. N,N-dimethylethanolamine (80-100% neutralized) was then added as a neutralizing agent. Water was gradually added until a homogeneous dispersion (30-50% solids content) was obtained. The mixture was allowed to cool to room temperature. The resulting dispersion was filtered and collected.

[0212] Example 10: Preparation of coating formulation

[0213] Solvent-based formulations were prepared and the properties of the cured films were tested, replacing aqueous formulations. The coating properties reported in this paper for reverse impact, MEK bifriction, and total boil-off are expected to be approximate simulations of the aqueous formulation. All polyester resins were diluted to 50% by weight solids in Shellsol A150 ND (an aromatic solvent available from Shell Chemicals) prior to formulation. Solvent blends were prepared from mixtures of xylene, butanol, and MAK, respectively, at 30%, 30%, and 40% by weight. Empty, capped glass jars were labeled and pre-weighed to record the tare weight. For each formulation, the tare weight was weighed separately. BF 987 (available from Ineos as n-butylated benzoguanamine-formaldehyde resin), Cymel 325 (available from Allnex as melamine-formaldehyde resin), and Lanco (available from Lubrizol) TM Glidd 4415Wax Dispersion 5076 (DDBSA acid catalyst available from King Industries) and a solvent blend were added sequentially to the resin solution. This was then followed by dispermat... TM The formulation was sheared at 1500 rpm for 10-15 minutes using a Cowles blade on a high-speed disperser. Once complete, the glass jars containing the formulation were then tumbled overnight under ambient conditions with gentle stirring. The resulting coated formulations are listed in Table 25.

[0214] Table 25. Coating Formulations

[0215]

[0216]

[0217] Example 11: Coating Preparation and Testing

[0218] The solvent-based formulation prepared in Example 10 was applied to a metallic substrate, such as chromium-treated aluminum. The plate was cured at an elevated temperature, for example, 350°C for 28 seconds. Subsequently, the properties of the resulting coating, such as reverse impact, MEK bi-friction, and total saturation, were tested according to the test methods described above. The results are listed in Table 26.

[0219] Table 26. Coating Properties

[0220]

[0221]

[0222] The present invention has been described in detail with reference to the embodiments disclosed herein, but it should be understood that changes and modifications can be made within the spirit and scope of the present invention.

Claims

1. An aqueous coating composition comprising: a. Polyesters, which are reaction products comprising the following monomers: i. 30 to 60 mol% of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, which is a TMCD, based on the total molar amount of i-iv. ii. 20 to 69 mol% of diols other than TMCD, based on the total molar number of i-iv. iii. Triols in amounts of 0 to 8 mol% based on the total moles of i-iv. iv. 15 to 30 mol% of dimethylolpropionic acid based on the total moles of i-iv. v. 0 to 20 mol% of α,β-unsaturated diacids or anhydrides based on the total number of moles of v-vii. vi. 80 to 100 mol% of aromatic diacids based on the total molar number of v-vii, and vii. Aliphatic diacids in quantities of 0 to 20 mol% based on the total moles of v-vii, and b. Crosslinking agent, The polyester has an acid value of 30 to 100 mgKOH / g, a hydroxyl value of 6 to 30 mgKOH / g, a number-average molecular weight of 4,000 to 25,000 g / mole, and a weight-average molecular weight of 13,000 to 200,000 g / mole.

2. The aqueous coating composition according to claim 1, wherein the diol (ii) other than TMCD is selected from one or more of 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, neopentyl glycol and 2,2,4-trimethyl-1,3-pentanediol.

3. The aqueous coating composition according to any one of claims 1-2, wherein the triol (iii) is trimethylolpropane.

4. The aqueous coating composition according to claim 1, wherein the α,β-unsaturated diacid or anhydride (v) is selected from one or more of maleic anhydride, maleic acid, fumaric acid, itaconic anhydride and itaconic acid.

5. The aqueous coating composition according to claim 1, wherein the aromatic diacid (vi) is selected from one or more of isophthalic acid and its esters, and terephthalic acid and its esters.

6. The aqueous coating composition according to claim 1, wherein the aliphatic diacid (vii) is selected from one or more of succinic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid.

7. The aqueous coating composition according to claim 1, wherein the aliphatic diacid (vi) is sebacic acid, adipic acid, or a mixture thereof.

8. The aqueous coating composition according to claim 1, wherein the polyester (a) has an acid value of 50-100 mgKOH / g.

9. The aqueous coating composition according to claim 1, wherein the polyester (a) has a Tg of 40-110°C.

10. The aqueous coating composition according to claim 1, wherein the polyester (a) is manufactured using a titanium catalyst.

11. The aqueous coating composition of claim 1, wherein the aqueous coating composition further comprises a neutralizing agent and water.

12. The aqueous coating composition according to claim 1, wherein the aqueous coating composition further comprises an organic co-solvent.

13. The aqueous coating composition according to claim 1, wherein the crosslinking agent is one or more selected from isocyanates, amino resins and phenolic resin crosslinking agents.

14. The aqueous coating composition according to claim 1, wherein the amount of polyester (a) is 50-90% by weight based on the total weight of (a) and (b), and the amount of crosslinking agent (b) is 10-50% by weight.

15. An article, at least a portion of which is coated with an aqueous coating composition according to any one of the preceding claims.

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