FIELD OF THE INVENTION

[001] The present invention relates to packaging coating compositions, especially food and beverage packaging coating compositions. The packaging coating compositions comprise a solvent borne alkyd resin, and a crosslinker, wherein the solvent borne alkyd resin comprises an aromatic dicarboxlic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.

BACKGROUND OF THE INVENTION

[002] In modern life, a variety of coatings are applied on the surface of food and beverage packages to form a protective coating. For example, coil coating and/or sheet coating are usually used to apply the coating on the metal container or the material from which the container will be fabricated. The coil coating and/or sheet coating refer to a process for coating coil or sheet substrates including stainless steel, tin plated steel, or aluminum substrates with an appropriate composition. Then, the coated substrate can be manufactured into can body, bottom, lid, and/or cover. In addition, the coating composition also can be applied onto an already formed can body, bottom, lid and/or cover such as by spray coating and/or dip coating the part, and then curing. The coating for food and beverage packages usually can be applied on the substrate at high speed, while also providing necessary performance to meet the needs of end users, for example, the formed coating layer should be safe for contacting with food and beverage, and/or have excellent adhesion to the substrate.

[003] Solvent borne polyester coating is commonly used for packaging coatings because of its excellent mechanical properties, stain resistance and outdoor durability performance. However, the solvent borne polyester coating has a disadvantage in its high VOC content. The solvent evaporation during can coating not only causes great energy consumption, but also may be unfriendly to the environment. Therefore, high solid content polyester coatings, which are more environmentally friendly because of their low solvent content, are highly desired.

SUMMARY OF THE INVENTION

[004] The present invention provide a solvent borne alkyd resin, comprising the reaction product of a mixture comprising an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.

[005] In certain embodiments the present invention provides methods for preparing such a solvent borne alkyd resin comprising: mixing an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid, bis(hydroxyalkyl) bisphenol A, and optional solvent, with rapid stirring, and heating the mixture to at least 150°C; heating under reflux, and gradually raising the temperature to at least 240°C, until the reaction mixture becomes transparent; cooling to at least 140°C; and filtering the solid product.

[006] In other embodiments the present invention provides a solvent borne coating composition, comprising the solvent borne alkyd resin of the present invention, and a crosslinker.

[007] In other embodiments the present invention provides a package coated with the solvent borne coating composition of the present invention, and a process for coating a package at least in part with the solvent borne coating composition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[008] The present invention provides a solvent borne alkyd resin, which comprises the reaction product of a mixture comprising an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid and bis(hydroxyalkyl) bisphenol A.

The present invention also provides a coating composition, which comprises: the solvent borne alkyd resin of the present invention and a crosslinker.

[009] The aromatic dicarboxylic acid refers to aromatic compounds containing 8-16 carbon atoms and two carboxylic acid functional groups, wherein the aromatic moieties include, but are not limited to, an aromatic moiety derived from benzene, naphthalene, anthracene, and/or xenene. In embodiments, the aromatic dicarboxylic acids comprise phthalic acid, isophthalic acid and/or terephthalic acid. Embodiments wherein the aromatic dicarboxylic acids comprise isophthalic acid and/or terephthalic acid are particularly suitable.

[0010] The aliphatic diol refers to aliphatic compounds containing 2-10 carbon atoms and two hydroxyl functional group. In embodiments, the aliphatic diol comprises propyl glycol, butyl glycol, pentyl glycol, neopentyl glycol and/or hexyl glycol. In particularly suitable embodiments, the aliphatic diol comprises propyl glycol, butyl glycol, pentyl glycol and/or neopentyl glycol, such as butyl glycol and/or neopentyl glycol. [0011] The fatty acid refers to saturated or unsaturated aliphatic compounds containing 6-20 carbon atoms with a terminal carboxy group. In embodiments, the fatty acid can be a mixture of several acid compounds with different length of carbon chains. In embodiments, the fatty acid comprises soyabean fatty acid, coconut fatty acid, and/or lauric acid. In particular suitable embodiments, the fatty acid comprises soyabean fatty acid.

[0012] The bis(hydroxyalkyl) bisphenol A is a bisphenol A derivative obtained by substituting both of the hydrogen atoms on the hydroxyl groups of bisphenol A with two hydroxyalkyls having 1-6 carbon atoms. The two hydroxyalkyl substitutions can be the same or different. In embodiments, the two hydroxyalkyls substitutions are the same. In embodiments, the bis(hydroxyalkyl) bisphenol A comprises bis(hydroxyethyl) bisphenol A, bis(hydroxypropyl) bisphenol and/or bis(hydroxybutyl) bisphenol A. In particularly suitable embodiments, the bis(hydroxyalkyl) bisphenol A comprises bis(hydroxyethyl) bisphenol A, and/or bis(hydroxypropyl) bisphenol, such as bis(hydroxyethyl) bisphenol A.

[0013] In embodiments, the solvent borne alkyd resin, based on its total weight, comprises 10-60 wt%, such as 15-50 wt%, or 20-40 wt% of an aromatic dicarboxylic acid.

[0014] In embodiments, the solvent borne alkyd resin, based on its total weight, comprises 1-40 wt%, such as 3-30 wt%, or 5-20% of an aliphatic diol.

[0015] In embodiments, the solvent borne alkyd resin, based on its total weight, comprises 5-55 wt%, such as 5-45 wt%, 5-35 wt%, or 10-20 wt% of bis(hydroxyalkyl) bisphenol A.

[0016] The solvent borne alkyd resin further comprises a solvent. In embodiments, the solvent comprises aromatic hydrocarbons. In particularly suitable embodiments, the solvent comprises high boiling point aromatic hydrocarbons. In embodiments, the solvent borne alkyd resin, based on its total weight, comprises 1-30 wt%, such as 5-25 wt%, 10-20 wt%, or 10-15 wt% of solvent.

[0017] The solvent borne alkyd resin may, in certain embodiments, further comprise a catalyst, which can be any suitable catalyst, such as an organotin compound. In embodiments, the solvent borne alkyd resin, based on its total weight, comprises 0-1 wt%, such as 0-0.5 wt%, 0.1-0.3 wt%, or 0.1 wt% of the catalyst.

[0018] The alkyd resin can be prepared in accordance with the following steps:

a. mixing an aromatic dicarboxylic acid, an aliphatic diol, a fatty acid, bis(hydroxyalkyl) bisphenol A, and optional solvent, at a stirring speed of 200-400 rep/min, and heating the mixture to at least 150 ^° C ;

b. heating under reflux, and gradually raising the temperature to at least 240 ^° C , until the reaction mixture becomes transparent;

c. cooling to at least 140 ^° C ; and

d. filtering the solid product.

[0019] The present invention provides a solvent borne coating composition, which comprises a solvent borne alkyd resin of the present invention and a crosslinker.

[0020] The crosslinker can be any crosslinker that reacts with the alkyd. In certain embodiments, the crosslinker comprises an amino resin and/or a blocked isocyanate. The amino resin used may be a complex mixture containing different functional groups and molecule types obtained by the condensation between formaldehyde and an amine, and followed by alkylation of the obtained hydroxymethyl with alcohol. In embodiments, the amino resin can be butylated amino resin such as cymel 1156, and/or butylated benzene substituted amino resin such as cymel 659.

[0021] The blocked isocyanate is a polyurethane obtained by reacting terminal isocyanate groups with a compound having an active hydrogen atom, and then blocking the -NCO reactive functionality of the product that wil become unblocked during cure. In embodiments, the blocked isocyanate can be for example blocked isocyanate Desmodur BL4265.

[0022] The solvent borne coating compositions of present invention, based on their total weight, can comprise 20-80 wt%, such as 30-70 wt%, or 40-60 wt% of the solvent borne alkyd of the present invention.

[0023] The solvent borne coating composition of the present invention may, in certain embodiments, further comprise a polyester resin. In certain embodiments, the additional polyester may be crosslinked by the same crosslinker as the solvent borne alkyd, while in other embodiments an additional crosslinker may be used; such crosslinker can be selected by one skilled in the art based on the polyester being used.

[0024] The polyester resin used in the present invention can be any suitable polyester resin. In embodiments, the polyeseter resin comprises an aromatic dicarboxylic acid and/or anhydride thereof, an aliphatic alcohol, and optionally a catalyst, and/or a solvent. The aromatic dicarboxylic acid and/or anhydride thereof can comprise, for example, phthalic acid, isophthalic acid, terephthalic acid and/or anhydride thereof. In suitable embodiments, the aromatic dicarboxylic acid and/or anhydride thereof comprises phthalic anhydride. The aliphatic alcohol can comprise, for example, monobasic alcohols, diols and triols, such as isooctanol, isononanol, isodecanol, butyl glycol, pentyl glycol, neopentyl glycol, trimethylolpropane, and/or triethylolethane. The catalyst, if used, can be any suitable catalyst used in the preparation of a polyester, for example, organotin catalyst, such as FASCAT 4201 catalyst from Newtop Chemical Materials Co. Ltd, Shanghai. Any other polyester suitable for use in a packaging coating can also be used.

[0025] The solvent borne coating composition of the present invention may, in certain embodiments, further comprise an epoxy resin suitable for use in packaging coatings, such as those commercially available from Momentive, an example of which is EPON860. In certain embodiments, the epoxy may be crosslinked by the same crosslinker as the solvent borne alkyd, while in other embodiments an additional crosslinker may be used; such crosslinker can be selected by one skilled in the art based on the epoxy being used.

[0026] The solvent borne coating composition of the present invention may, in certain embodiments, further comprises optional ingredients. Typically, the coating compositions of the present invention comprise a solvent, such as an organic solvent, or a mixture of water and an organic solvent. Examples of suitable organic solvents include aliphatic hydrocarbons such as solvent oil and a high flash point VM & P Naphtha; aromatic hydrocarbons such as benzene, toluene, xylene, high boiling point aromatic hydrocarbons including S-100A, S-100B, S-100C, S-150, S-180, S-200 available from HUALUN Chemical Industry Co., Ltd, Solvesso™ 100, Solvesso™ 150, Solvesso™ 200 available from ExxonMobil Chemical; alcohols, such as ethanol, n-propanol, isopropanol, n-butanol and the like; ketones, such as acetone, cyclohexanone, methyl isobutyl ketone and the like; esters, such as ethyl acetate, butyl esters, and the like; glycols, such as ethylene glycol; glycol ethers, such as methoxy propanol and ethylene glycol monomethyl ether, ethylene glycol monobutyl ether. Mixtures of various organic solvents also can be used. In embodiments, the solvent borne coating composition of the present invention comprises aromatic hydrocarbons such as Solvesso™ 100, Solvesso™ 150, and/or alcohols such as propanol and butanol. The solvent used in the coatings of the present invention, based on total coating weight, comprises 5-30 wt%, such as 10-25 wt%, or 12-20 wt% of solvent.

[0027] Another optional ingredient is a catalyst to increase the curing or crosslinking rate of the coating composition. Generally an acid catalyst can be used. In embodiments, the solvent borne coating composition of the present invention, based on its total weight, comprises 0.05 to 1 wt%, such as 0.1 to 0.5 wt% of a catalyst. Examples of suitable catalysts include dodecylbenzenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, dinonyl naphthalene disulfonic acid and phenyl phosphonic acid.

[0028] Yet another useful optional ingredient is a leveling agent or surfactant. The leveling agent is added to a coating composition to decrease surface tension gradients, thereby improve the leveling property of the coating composition. Suitable surfactants include, but are not limited to, polydimethylsiloxane, polyether-polyester-modified organic silicone and alkyl-modified organosiloxane. In embodiments, the solvent borne coating composition of the present invention, based on its total weight, comprises 0.05 to 1 wt%, such as 0.1 to 0.5 wt% of a leveling agent. Examples of commercially available levelling agents useful in the solvent borne coating compositions of the present invention include BYK 358 leveling agent, and/or BYK 300 organosiloxane levelling agent.

[0029] The solvent borne coating composition of the present invention may also include additives commonly used in the coating industry, including, for example colorants, plasticizers, abrasion resistant particles, membrane strengthening particles, flow control agents, thixotropic agents, rheology modifiers, antioxidants, biocides, defoamers, wetting agents, dispersing agents, adhesion promoters, clay, hindered amine light stabilizers, UV light absorbing stabilizers, stabilizers, fillers, grinding vehicle agents and other common additives, or combinations thereof.

[0030] The terms "solvent borne resin" and/or "solvent borne coating composition" refer to resin and/or coating composition which can be dissolved or dispersed in solvent prior to use to form a solution, a dispersion, an emulsion, a suspension and any other suitable forms, wherein the solvent can be an organic solvent and/or a mixture of water and an organic solvent, thereby dissolving or dispersing the resin and/or coating composition components. The solvent may be reactive, non-reactive or a mixture thereof. In some embodiments, the organic solvent is selected to be volatile enough to be substantially completely removed from the coating composition in the curing process by evaporation, for example, such as heating to 150-180 °C for 5-15 minutes.

[0031] In certain embodiments, the solvent borne alkyd resin and/or coating comprising the same may be substantially free, may be essentially free and/or may be completely free of bisphenol A and derivatives or residues thereof, including bisphenol A and bisphenol A diglycidyl ether ("BADGE"). A solvent borne alkyd resin and/or coating that is substantially bisphenol A free is sometimes referred to as "BPA non intent" because BPA, including derivatives or residues thereof, are not intentionally added but may be present in trace amounts such as because of impurities or unavoidable contamination from the environment. The solvent borne alkyd resin and/or coatings of the present invention can also be substantially free, essentially free and/or completely free of bisphenol F and derivatives or residues thereof, including bisphenol F and bisphenol F diglycidyl ether ("BPFDG"). The term "substantially free" as used in this context means the solvent borne alkyd resin and/or coating compositions contain less than 1000 parts per million (ppm), "essentially free" means less than 100 ppm and "completely free" means less than 20 parts per billion (ppb) of any of the above compounds or derivatives or residues thereof.

[0032] The solvent borne coating composition of the present invention may be applied to any of the substrates known in the art, for example, automotive substrates, industrial substrates, packaging substrate, floors and furniture. The substrate may be metallic or non-metallic. The metal substrates include, for example, steel, tin-plated steel, galvanized steel, aluminum, aluminum foil. Non-metallic substrates include polymers, plastics, polyester, polyolefm, polyamide, cellulose, polystyrene, polyacrylic acid, poly (ethylene naphthalate ester), polypropylene, polyethylene, nylon, EVOH, polylactic acid, poly (ethylene terephthalate) (PET), polycarbonate, polycarbonate, acrylonitrile butadiene styrene (PC/ABS), polyamide , wood, wood composite panels, cement, stone, glass, paper, cardboard, textiles, leather, including synthetic and natural leathers, as well as other non-metallic substrates. In embodiments, the solvent borne coating composition may be applied to steel, tin-plated steel, galvanized steel, aluminum substrates. In certain embodiments the solvent borne coating composition is applied to food and beverage packages. Accordingly, the present invention is further directed to a substrate coated at least in part with the coating of the present invention, wherein the substrate comprises a package or any part thereof, such as a crown cap.

[0033] The coating composition of the present invention, through any standard technique in the art for coating methods, such as electric coating, spraying, electrostatic spraying, dip coating, roll coating, brush coating methods. In embodiments, the coating has a dry film thickness of 2-10 μιη, such as 3-8um, or 4-6 um.

[0034] The coating composition of the present invention may be used alone or in combination with one or more other coating compositions. For example, the coating composition of the present invention may either contain a colorant or not, and can be used as a primer, base coat and/or topcoat.

[0035] The coating composition of the present invention is suitable for package coatings, especially food and beverage package coatings. For example, the coating can be applied on metal substrates to delay or prevent corrosion, to provide decorative coatings, and/or to make the metal substrate easier to handle during the manufacturing process. The coating can be applied to the inside of the package to prevent the contents of the package from coming into contact with the metal. The contact of metal substrate with food or beverages may cause corrosion of the metal subtrate, thereby contaminating the food or beverage, especially when the food or beverage is acidic. The coating may also be applied on the outside of the package. The solvent borne coating composition of the present invention is suitable for metal sheet material, for example, the metal sheet material for the manufacture of cans, can end, including the can lid, cap and/or bottom. The coating is generally applied on the metal substrate before cutting and punching, therefore it generally has good flexibility and scalability. For example, the metal substrate is coated with the coating composition on both sides, and then then stamped and formed cans, can lids, bottoms or caps. However, the coating also can be applied after the cans, can lids, bottoms and caps are formed. The coating may be resistant to borehole, corrosion, haze and/or blistering. Certain coatings of the present invention are particularly applicable for use with coiled metal stock, such as the coiled metal stock from which the ends of cans are made ("can end stock"), and end caps and closures are made ("cap/closure stock"). Since coatings designed for use on can end stock and cap/closure stock are typically applied prior to the piece being cut and stamped out of the coiled metal stock, they are typically flexible and extensible. For example, such stock is typically coated on both sides. Thereafter, the coated metal stock is punched. For can ends, the metal is then scored for the "pop-top" opening and the pop-top ring is then attached with a pin that is separately fabricated. The end is then attached to the can body by an edge rolling process. A similar procedure is done for "easy open" can ends. For easy open can ends, a score substantially around the perimeter of the lid allows for easy opening or removing of the lid from the can, typically by means of a pull tab. For caps and closures, the cap/closure stock is typically coated, such as by roll coating, and the cap or closure stamped out of the stock; it is possible, however, to coat the cap/closure after formation. Coatings for cans subjected to relatively stringent temperature and/or pressure requirements should also be resistant to cracking, popping, corrosion, blushing and/or blistering. [0036] The present invention also relates to a package, wherein at least a portion of the package is coated with the solvent borne coating composition of the present invention. In some embodiments, the package is a metal can. The term "metal can" includes any type of cans and containers which can accommodate contents. Examples of metal cans include food cans and beverage cans. The food cans and/or beverage cans refer to any type of cans and containers accommodating food and/or beverage. The metal cans also specifically include a metal can cover, for examples caps including crown caps, and lids including screw down lids. In addition to food and beverage, the metal can may also be used to accommodate other items, including, but not limited to personal care products, insect sprays, paint, and any other suitable packing contents. The term "metal cans" also specifically includes metal caps and/or closures such as bottle caps, screw top caps and lids of any size, lug caps, and the like. The metal cans can be used to hold other items as well, including, but not limited to, personal care products, bug spray, spray paint, and any other compound suitable for packaging in an aerosol can. The cans can include "two-piece cans" and "three-piece cans" as well as drawn and ironed one-piece cans; such one-piece cans often find application with aerosol products. Packages coated according to the present invention can also include plastic bottles, plastic tubes, laminates and flexible packaging, such as those made from PE, PP, PET and the like. Such packaging could hold, for example, food, toothpaste, personal care products and the like.

[0037] The solvent borne coating composition of the present invention may be applied to interior and/or exterior of the package. In some embodiments, the coating is applied by rolling on sheet or coil substrate, then cured and punched to obtain can end including lid, or cap. In some embodiments, the solvent borne coating composition of the present invention may be applied on the ink, varnish and/or color decoration layer pre-formed on the can body, top, bottom, lid and/or cap. In some embodiments, the solvent borne coating composition of the present invention may be wet-on-wet applied on the ink, varnish and/or color decoration layer.

[0038] It has bee surprisely discovered that the alkyd resin and coating comprising the same as described herein, may offer physical properties desirable for packaging coatings, for example low viscosity and/or good levelling, hardness, abrasion resistance and/or flexibility. The coating compositions of the present invention also have a lower curing temperature than many packaging coatings used in the art. In embodiments, the coating compositions of the present invention cure at a temperature of 150-180°C, such as 155-175°C, such as 160-170°C. Furthermore, the ability of the coating compositions of the present invention to be wet-on-wet applied on an ink layer simplifies the coating procedure and saves cost.

[0039] For purposes of this description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing values, ranges, amounts or percentages, for example, quantities of ingredients, used in the specification and claims may be read as if prefaced and as being modified in all instances by the term "about," even if the term does not expressly appear. Also, it should be understood that any numerical range recited herein is intended to include the endpoints of those ranges and all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0040] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0041] As used in this specification and the appended claims, singular encompasses plural and vice versa, unless specifically stated otherwise. For example, although reference is made herein to the articles "a," "an," and "the," plural referents are included unless expressly and unequivocally limited to one referent. For example, although reference is made herein to "a" solvent borne alkyd resin, "an" aromatic dicarboxylic acid, "an" aliphatic diol, "a" fatty acid, "a" bis(hydroxyalkyl)bisphenol A, "a" crosslinker and the like, one or more of each of these components, and of any other components, can be used. In addition, in this application, the use of "or" means "and/or" unless specifically stated otherwise, even though "and/or" may be explicitly used in certain instances. "Including," "for example," "such as" and like terms means including, for example, such as, but not limited to.

[0042] The various embodiments and examples of the present invention as presented herein are each understood to be non-limiting with respect to the scope of the invention.

[0043] The invention will be further described by reference to the following examples. The following examples are merely illustrative of the invention and are not intended to be limiting.

EXAMPLES

[0044] The following examples are presented to demonstrate the general principles of the invention. The Examples describe the preparation of solvent borne alkyd resin and solvent borne coating composition according to embodiments of the present invention and methods of preparation. All amounts listed are described in parts by total weight, unless otherwise indicated. The invention should not be construed as limited to the specific examples presented.

[0045] Example 1 : Preparation of a solvent borne alkyd resin

[0046] The formulation is as below, based on the total weight of the solvent borne alkyd resin:

[0047] The alkyd resin was prepared in accordance with the following steps:

a. isophthalic acid, terephthalic acid, soyabean fatty acid, neopentylglycol, glycerol, hydroxyethyl bisphenol A, butyl glycol, organic tin catalyst, and Solvesso™ 100 were mixed with rapid stirring at 400rpm, and heated to at least 150°C;

b. the mixture was heated under reflux, and gradually the temperature was raised to at least 240°C, until the reaction mixture became transparent;

c. the mixture was then cooled to at least 140°C, and the solid product filtered off to obtain the alkyd resin (Referred to as alkyd resin SP0004 hereafter) of the present invention.

[0048] Example 2: Preparation of a polyester resin

[0049] The formulation is as below, based on the total weight of the polyester resin:

[0050] The polyester resin was prepared in accordance with the following steps: a. pthalic anhydride, isooctanol, trimethylolpropane, FC 4201 catalyst, xylene, Solvesso™ 150, and ethylene glycol butyl ether were mixed with rapid stirring at 400rpm, and heated to at least 150°C;

b. the mixture was heated under reflux, and gradually the temperature was raised to at least 240°C, until the reaction mixture became transparent;

c. the mixture was then cooled to at least 140°C, and the solid product filtered off to obtain the polyester resin referred to as polyester resin SP0001 hereafter.

[0051] Example 3: Preparation of an solvent borne coating composition

[0052] The formulation is as below, based on the total weight of the solvent borne coating composition:

Component Weight, %

Alkyd resin SP0004 50.0%

Polyester resin SP0001 10.0%

DIC EPON860 5.0%

Cymel 1156 10.0%

Cymel 659 3.0%

Blocked isocyanate BL4265 1.0%

BYK358 leveling agent 0.1%

BYK300 organosilicone leveling agent 0.01%

Lauryl benzenesulfonic acid 0.1%

Ethylene glycol butyl ether 6.0% Solvesso™ 100 6.0%

Solvesso™ 150 5.0%

Butanol 3.79%

[0053] The coating composition was prepared in accordance with the following steps:

a. the solvent borne alkyd resin SP0004, polyester resin SP0001 and DIC EPON860 were added to a mixing kettle, and stirred at a low speed of 400 rep/min; b. Cymel 1156, Cymel 659 and blocked isocyanate BL4265 were slowly added into the mixed resin while stirring;

c. the auxiliaries including BYK 358 levelling agent, BYK 300 organosilicone leveling agent, lauryl benzenesulfonic acid, and ethylene glycol butyl ether were pre-dissolved in a solvent mixture of Solvesso™ 100, Solvesso™ 150 and butanol; d. the pre-dissolved auxiliaries were added into the mixed resin while stirring; e. the speed was increased to 1000 rep/min, and the mixture stirred for 30 minutes;

f. the reaction product was filtered to obtain the coating composition of the present invention.

[0054] Example 4: Preparation of a solvent borne coating composition

[0055] The formulation is as below, based on the total weight of the solvent borne coating composition:

[0056] The coating composition was prepared in accordance with the procedure described in Example 2. [0057] Coating Example 1 : Application of a coating composition

[0058] The coating composition prepared in Example 3 was applied and cured in accordance with the following steps to form an coating layer:

Step 1. A solvent borne ink composition were applied on tin plated steel sheet substrates by roll coating;

Step 2. The coating composition prepared in Example 3 was wet-on- wet applied on the ink layer by roll coating in amounts of about 15 grams of the coating composition per square meter;

Step 3. The coated substrate was then placed in an oven at a temperature of about 170 degrees Celsius for 15 minutes, to obtain a dried coating layer of about 9 grams per square meters.

[0059] Coating Example 2: Application of a coating composition

[0060] The coating composition prepared in Example 4 was applied and cured in accordance with the steps described in Coating Example 1 except using the coating composition of Example 4 instead of the coating composition of Example 3 to form a coating layer.

[0061] Performance Test

[0062] The coating compositions prepared in Examples 3-4 were tested for their viscosity, and the coatings prepared in Coating Example 1 and 2 were testing for their processability, and abrasion resistance. The testing methods are described as below:

[0063] Viscosity Test: A Ford cup #4 was used to test the viscosity at a temperature of 25 degrees Celsius. The cup was filled the coating composition of the present invention, and measure the time required for emptying the cup. The viscosity of the coating composition is desirably in the range of about 60s to about 160s.

[0064] Processablity Test:

Materials: coated substrate plates prepared in Coating Examples 1 and 2, falling ball impact tester, 5% copper sulfate solution, and stopwatch;

Method: the falling ball impact tester was used to impact the coated substrate plates at a rate of lkg/50cm. After impact, the coated substrate plates were soaked in the copper sulphate solution soak for 2 minutes and then inspected for any corrosion areas.

[0065] Abrasion Resistance Test:

Materials: 75 coated substrate plates prepared as described in each of Coating Examples 1 and 2, abrasion tester, analytical balance, stopwatch, and soft brush;

Method: The 75 coated substrate plates were divided into three groups, 25 plates in each group. The mass of each plate was measured with an analytical balance to an accuracy of 0.1 mg, and the total mass of 25 plates in a group were calculated and recorded. Then, a group of 25 plates was placed in the abrasion tester at the same time, rotated at a speed of 20 rep/min for 50 min. The group of 25 plates were taken out and the surfaces were cleaned with a soft brush to remove crumbles. Then the mass of each plates were again measured and the total mass of 25 plates in a group were calculated and recorded. The difference between the total mass before and after the abrasion was the abrasion value. The other two groups of 25 plates were tested following the same procedure. The average abrasion value of the three groups of coated substrate plates was the abrasion value for the coating. An abrasion value of less than 16 mg is desired.

[0066] Appearance Test:

Material: 10 coated substrate plates prepared as described in each of Coating Examples 1 and 2.

Method: observe the appearance of each coated substrate with the naked eye.

[0067] Pasteurization Test:

Material: 10 coated substrate plates prepared as described in each of Coating Examples 1 and 2.

Method: the coated substrate plates were immersed in water at 80°C for 30 min, then taken out and observed with the naked eye to determine whether there is water stain or not.

[0068] Test Results:

Table 1

[0069] The results shows that the coating composition of the present invention has appropriate viscosity, and high solid content which is desired in food and beverage package coating process.

Table 2

Coating Example NO. Coating Example 2 Coating Example 3

Falling Ball Impact No cracks No cracks

Abrasion (25 plates total) (mg) 12 mg 11 mg No gloss loss No gloss loss

Appearance

No coating defeat No coating defeat

Pasteurization No water stain No water stain

[0070] The results shows that the coating composition of the present invention can be wet-on-wet applied on ink, and cured to form a coating layer with great anti-impact, abrasion resistance performance in addition to good appearance. Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications that are within the spirit and scope of the invention, as defined by the appended claims.