Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
  • C09D167/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
  • B32B15/09—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyesters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D25/00—Details of other kinds or types of rigid or semi-rigid containers
  • B65D25/14—Linings or internal coatings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D161/00—Coating compositions based on condensation polymers of aldehydes or ketones; Coating compositions based on derivatives of such polymers
  • C09D161/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/65—Additives macromolecular
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
  • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
  • C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
  • C08L61/04—Condensation polymers of aldehydes or ketones with phenols only
  • C08L61/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
  • C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
  • C08L61/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
  • C08L61/28—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds with melamine
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
  • Y10T428/1355—Elemental metal containing [e.g., substrate, foil, film, coating, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal
  • Y10T428/31681—Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Definitions

• the present invention relates to a polyester-based coating composition, and more specifically, a polyester-based coating composition having excellent resistance to embrittlement with time, workability, corrosion resistance, abrasion resistance, retort resistance, and blocking resistance, and the coating composition.
• the present invention relates to a coated metal plate, a metal lid, and a metal container formed by painting an object.
• the organic coating that protects the metal container or metal lid prevents the metal substrate from being corroded by the contents, etc., and the metal container is subjected to mechanical processing such as neck-in processing, bead processing, and lid tightening processing.
• a metal lid such as an easy open end (hereinafter sometimes referred to as “EOE”), it is subjected to severe processing such as score processing and rivet processing, so it is used for a metal container or metal lid
• EEE easy open end
• severe processing such as score processing and rivet processing
• Patent Document 1 proposes a coating composition in which a predetermined amount of a hydroxyl group-containing polyester resin, a specific phenol resin crosslinking agent, and an acid catalyst is blended. It is described that it is possible to form a coating film that is excellent in the balance of adhesiveness, adhesiveness, curability, hygiene and boiling water resistance.
• Patent Documents 2 and 3 listed below describe resin compositions for paints using a polyester resin containing a molecule in which a pendant carboxyl group is introduced into the molecular chain.
• the water-based resin composition described in Patent Document 2 In the product, it is excellent in curability, workability, retort resistance, hygiene, spray paintability, and water dispersibility, and in the coating resin composition described in Patent Document 3, the adhesion to the metal surface is improved. It is described that it is particularly excellent and can satisfy high workability and corrosion resistance.
• Patent Document 4 includes a polyester resin having a low Tg and a crosslinking agent having 2-methyl-1,3-propanediol, 1,4-butanediol and 1,4-cyclohexanedimethanol as polyalcohol components as essential components.
• a polyester resin composition is proposed that has processability, retort resistance, flavor properties, content resistance properties, feathering properties, and sulfur resistance, as well as high processability required as an internal paint for EOE, It is described that it has feathering properties and can suppress deterioration of workability over time.
• Patent Document 5 proposes a coating composition containing an appropriately vertically branched bivalent alcohol component while appropriately branching the polymer polyester resin, and the workability of the coating film does not decrease with time. It describes that it is excellent in the balance between adhesion to the material, hardness, and workability. Patent Document 4 describes that a polyester resin having a glass transition temperature (Tg) of 20 to 50 ° C. is preferred, but Patent Document 5 does not mention the glass transition temperature.
• Tg glass transition temperature
• an object of the present invention is to further improve the resistance to embrittlement with time, and to obtain a coating film excellent in all of the coating film performance such as workability, corrosion resistance, abrasion resistance, blocking resistance, and retort resistance. It is to provide a composition.
• a coating composition comprising a mixed polyester resin mixed with a polyester resin (B) at ⁇ 20 to 25 ° C. containing a crosslinking agent and a curing catalyst.
• the polyester resin (A) is a polyester resin which has been given the acid value of the resin by a ring-opening addition reaction of a compound having one or more carboxylic anhydride structures in the molecule; 2.
• Tgmix is the glass transition temperature (K) of the mixed polyester resin
• Tga is the glass transition temperature (K) of the polyester resin (A)
• Tgb is the glass transition temperature (K) of the polyester resin (B)
• Wa is the polyester resin.
• the weight fraction of (A) and Wb are the weight fraction of the polyester resin (B), respectively. 4).
• the crosslinking agent comprises a resol type phenol resin and / or an amino resin, and is blended in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the resin solids of the polyester resins (A) and (B); 5.
• the curing catalyst is blended in an amount of 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the total resin solids; Is preferred.
• coated the said coating composition is also provided.
• the coating composition is preferably formed by coil baking.
• the present invention further provides a metal container or a metal lid on which a coating film made of a coating composition is formed.
• the reason for the occurrence of the embrittlement phenomenon with time which is one of the problems to be solved by the coating composition of the present invention, has not yet been elucidated, but the present inventors presume as follows: Yes. That is, it is considered that the coating film immediately after curing undergoes molecular reorientation (transition to an equilibrium state) due to enthalpy relaxation over time, resulting in embrittlement of the coating film and decrease in workability.
• the crosslink density of the cured coating film is increased and molecular motion is suppressed to suppress enthalpy relaxation, or the molecular motion is continuously maintained even at the storage temperature with time (non-equilibrium state).
• the cured coating film does not have sufficient workability from the beginning, and in the latter method, even though the embrittlement phenomenon with time of the cured coating film can be suppressed, the corrosion resistance of the contents, during the molding process It was found that the abrasion resistance of the coated metal plate, the blocking resistance of the coated metal plate, and the retort resistance during the sterilization treatment were not sufficient, and in any of the methods, sufficient coating performance in practical use could not be obtained.
• the polyester resin (A) capable of suppressing molecular motion to prevent enthalpy relaxation, which is a cause of embrittlement with time
• a cured coating film that increases the crosslinking density By using a combination of a polyester resin (B) having a low Tg, which can maintain molecular motion even at a storage temperature of a long time, embrittlement resistance over time, workability, corrosion resistance, abrasion resistance, blocking resistance, It came to invention of the coating composition which can form the coating film which was excellent in all coating-film performances, such as retort resistance.
• the coated metal plate formed by applying the coating composition of the present invention has the above-described excellent coating film performance, and can be suitably used for a metal container or a metal lid. Furthermore, the metal container and the metal lid of the present invention have excellent corrosion resistance and retort resistance.
• the coated metal plate and the metal lid using the coating composition of the present invention are excellent in workability both in the initial stage and after the lapse of time, and all of corrosion resistance, retort resistance, blocking resistance, and abrasion resistance.
• the metal lid is evaluated only for the metal lid, which is formed by processing a painted metal plate, while the painted metal container is generally formed after the container is molded. Since the coating film on the coated metal lid has a higher degree of processing, if a good evaluation can be obtained with a can lid, naturally a good evaluation can also be obtained with a metal container. Evaluation is conducted only in
• polyester resin (A) used in the coating composition of the present invention has an acid value in the range of 2 to 50 mgKOH / g, particularly 5 to 30 mgKOH / g, and a glass transition temperature (Tg) of 35 to 100 ° C., particularly 50 to As long as it is in the range of 90 ° C., polyester resins composed of various carboxylic acid components and alcohol components can be used. In the present invention, it is important that the acid value of the polyester resin (A) is in the above range, thereby improving the adhesion to the metal substrate and contributing to the improvement of workability.
• the adhesion to the substrate when the adhesion to the substrate is increased, it becomes difficult for corrosion-inducing substances (salts and acids) to reach the metal, and excellent corrosion resistance can be exhibited. Moreover, it contributes to increasing the crosslink density and suppressing the embrittlement of the coating film due to the enthalpy relaxation over time of the cured coating film. If the acid value is smaller than the above range, sufficient adhesion to the substrate may not be obtained, and it may be difficult to achieve both workability and corrosion resistance. The effect of suppressing embrittlement may not be sufficiently obtained. When the acid value is larger than the above range, the water resistance of the coating film may decrease. Moreover, when the glass transition temperature (Tg) of a polyester resin (A) is smaller than the said range, blocking resistance may be inferior. Moreover, when Tg is higher than the said range, the solubility to the solvent of a coating composition may be inferior.
• Tg glass transition temperature
• carboxylic acid component used in the polyester resin (A) examples include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, Aliphatic dicarboxylic acids such as dodecanedioic acid and dimer acid, unsaturated dicarboxylic acids such as (anhydrous) maleic acid, fumaric acid, dodecenyl succinic anhydride, terpene-maleic acid adduct, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthal Acid, hexahydroisophthalic acid, alicyclic dicarboxylic acid such as 1,2-cyclohexene dicarboxylic acid, trihydric or higher carboxylic acid such as (anhydrous) trimellitic acid, (anhydrous) pyrom
• Examples of the alcohol component used in the polyester resin (A) include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, , 3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl- 2-butyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1-methyl-1,8-octanediol, 3-methyl-1,6-hexanediol, 4-methyl- 1,7-heptanediol, 4-methyl-1,8-octanediol, 4-propyl-1,8-oc
• a carboxyl group is present in the middle of a molecular chain from the viewpoint of increasing the crosslinking density of the coating film and suppressing molecular motion to prevent enthalpy relaxation, which is a cause of embrittlement over time. It is particularly preferred to include molecules introduced in pendant form.
• a method for obtaining such a polyester is not limited to this. For example, a ring-opening addition reaction of a compound having one or more carboxylic acid anhydride groups in the molecule described in JP-A No. 2003-213201 is performed. Can be mentioned.
• the polyester resin (A) given the resin acid value by the ring-opening addition reaction of the compound having one or more carboxylic acid anhydride structures in the molecule is the total carboxylic acid used in the ring-opening addition reaction.
• the anhydride is 100 mol%
• 10 mol% or more of the carboxylic acid anhydride used is preferably a compound having two or more carboxylic anhydride groups in the molecule.
• a compound having two or more carboxylic anhydride groups in the molecule can modify not only the polyester resin terminal but also the carboxyl group in the resin molecule chain. By modifying the carboxyl group in the resin molecular chain, it becomes possible to impart an acid value without any limitation on the molecular weight.
• the adhesion between the base materials is further improved because of the low molecular weight between carboxyl groups, and a coating film with further excellent corrosion resistance can be obtained.
• the ring-opening addition reaction of a compound having one or more carboxylic acid anhydride structures in the molecule can be carried out by a known synthesis method.
• a method of adding (2) a method in which a carboxylic acid anhydride is added when the polyester resin is less than the target molecular weight (Mn ⁇ 3,000), and the molecular weight is increased to the target in a nitrogen atmosphere, and (3) an acid is added.
• Examples thereof include a method of kneading a polyester resin and a carboxylic acid anhydride that are not mixed with a melt extruder, and acid addition after melting in a batch.
• Examples of the compound having two or more carboxylic anhydride groups in the molecule include pyromellitic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentane. Tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, ethylene glycol bistrimellitic dianhydride, 2,3,2 ′, 3′-diphenyltetracarboxylic dianhydride, thiophene-2,3,4 , 5-tetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 5- (2,5-dioxo
• Examples of the carboxylic acid monoanhydride compound that can be used in combination with a compound having two or more carboxylic anhydride groups in the molecule include phthalic anhydride, maleic anhydride, succinic anhydride, maleic anhydride, trimellitic anhydride, anhydrous Examples thereof include monoanhydrides such as itaconic acid and citraconic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, and the like, and one or more of them can be selected and used. Of these, phthalic anhydride and trimellitic anhydride are preferred in view of versatility.
• the number average molecular weight of the polyester resin (A) used in the present invention is 3,000 to 100,000, preferably 8,000 to 50,000, more preferably 10,000 to 30,000. It is desirable. If the number average molecular weight is less than 3,000, the coating film becomes brittle and the processability may be inferior. If it exceeds 100,000, the coating workability may deteriorate.
• polyester resin (B) used in the coating composition of the present invention has an acid value in the range of 0 to 50 mgKOH / g, particularly 0 to 20 mgKOH / g, and a glass transition temperature (Tg) of ⁇ 20 to 25 ° C., particularly 0. As long as it is in the range of ⁇ 15 ° C., polyester resins comprising various carboxylic acid components and alcohol components can be used. It is important that the acid value is in the above range, and if it is larger than the above range, the water resistance of the coating film may be lowered. It is important that the glass transition temperature (Tg) is in the above range.
• the glass transition temperature (Tg) is larger than the above range, sufficient embrittlement resistance over time cannot be obtained. Moreover, when smaller than the said range, corrosion resistance, blocking resistance, and retort resistance may become inadequate.
• the carboxylic acid component and the alcohol component the carboxylic acid component and the alcohol component exemplified for the polyester resin (A) can be used.
• the polyester resin (B) preferably contains 2-methyl-1,3-propanediol, 1,4-butanediol and 1,4-cyclohexanedimethanol among the above alcohol components.
• the number average molecular weight of the polyester resin (B) used in the present invention is in the range of 3,000 to 100,000, preferably 8,000 to 50,000, more preferably, like the polyester resin (A). Is preferably in the range of 10,000 to 30,000. If the number average molecular weight of the polyester resin is less than 3,000, the coating film becomes brittle and the workability may be inferior. If it exceeds 100,000, the coating workability may be deteriorated.
• the polyester resin (B) can be appropriately selected from commercially available products.
• Byron 300 Toyobo, molecular weight (Mn) 23,000, acid value 2 or less, Tg 7 ° C.
• Byron 516 Toyobo, molecular weight (Mn) 30,000, acid value 2 or less, Tg ⁇ 17 ° C.
• Byron 560 Toyobo, molecular weight (Mn) 19,000, acid value 2 or less, Tg 7 ° C.
• Byron 630 Toyobo, molecular weight (Mn) 23,000, acid value 2 or less, Tg 7 ° C.
• Byron GK180 Toyobo, molecular weight (Mn) 10,000, acid value 5, Tg 0 ° C.
• Byron GK330 Toyobo, molecular weight (Mn) 17,000, acid value 2 or less, Tg 16 ° C.
• Elitel UE-3223 Unitika, molecular weight (Mn) 2
• a resol type phenol resin and / or an amino resin as a crosslinking agent.
• the resol type phenol resin include, as phenol monomers, o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, phenol, m-cresol, m -Ethylphenol, 3,5-xylenol, m-methoxyphenol, etc., which can be used singly or in combination, and these phenol monomers and formaldehyde were reacted in the presence of an alkali catalyst Is.
• a metacresol resin is preferable.
• commercially available products such as Sumitrite Resin PR-53893A (solid content 50%) manufactured by Sumitomo Durez Co., Ltd., CKS-3898 (solid content 50%) manufactured by Showa Denko KK can be used.
• amino resin for example, urea resin, melamine resin, benzoguanamine resin, and the like can be used. More specifically, methylated urea resin, methyl etherified urea resin, butyl etherified urea resin, and a mixture of methyl ether and butyl ether Etherified urea resins; methylolated melamine resins, methyl etherified melamine resins, butyl etherified melamine resins, mixed etherified melamine resins of methyl ether and butyl ether, etc .; methylolated benzoguanamine resins, methyl etherified benzoguanamine resins, butyl etherified benzoguanamines Resin, mixed etherified benzoguanamine resin of methyl ether and butyl ether, and the like.
• the crosslinking reaction is promoted, and more precise crosslinking can be efficiently performed at a low temperature and in a short time.
• phosphoric acid compounds such as organic sulfonic acid compounds such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid and camphorsulfonic acid, and neutralized amines thereof can be used.
• NACURE4054J phosphoric acid, manufactured by KING INDUSTRIES
• NACURE5076 diodecylbenzenesulfonic acid, manufactured by KING INDUSTRIES
• Cycat 4040 aromatic sulfonic acid, manufactured by Nippon Cytec Industries
• Cycat 4050 amine Block aromatic sulfonic acid, manufactured by Nippon Cytec Industries
• Cycat 600 aromatic sulfonic acid, manufactured by Nippon Cytec Industries
• Cycat 602 amine block aromatic sulfonic acid, manufactured by Nippon Cytec Industries
• the coating composition of this invention contains a crosslinking agent and a curing catalyst in the mixed polyester resin obtained by mixing the polyester resin (A) and the polyester resin (B).
• the ratio of the polyester resin (B) having a low Tg is 1 or less, the resistance to embrittlement with time deteriorates remarkably, and the post-aging processability of the coated plate cannot maintain the initial processability. This may cause a problem in practical use.
• the glass transition temperature calculated by the above formula (1) of the mixed polyester resin obtained by mixing the polyester resin (A) and the polyester resin (B) is 35 ° C. or more, particularly 40 to 80. It is desirable to be in the range of ° C. When the Tg is smaller than the above range, the blocking resistance is inferior. Moreover, when using as a can inner surface coating material, since a flavor property is required, it is preferable that it is Tg of 40 degreeC or more. From the viewpoint of solubility of the coating composition in a solvent, the upper limit is preferably 80 ° C. or less.
• the crosslinking agent is preferably in the range of 1 to 30 parts by weight, particularly 5 to 20 parts by weight, based on 100 parts by weight of the mixed polyester resin in which the polyester resin (A) and the polyester resin (B) are mixed. is there.
• the addition amount of the crosslinking agent is less than 1 part by weight, the curability becomes insufficient, and the resistance to embrittlement with time, workability, content resistance, retort resistance, and blocking resistance may be inferior.
• the curing catalyst is 0.1 to 3.0 parts by weight, particularly 0.1 to 2. It is suitable to be in the range of 0 part by weight.
• the blending amount of the curing catalyst When the blending amount of the curing catalyst is less than the above range, the effect of promoting the curing reaction obtained by blending the curing catalyst is not sufficiently obtained, while when the blending amount of the curing catalyst is larger than the above range. In some cases, the curing acceleration effect is large and the workability is insufficient.
• Conventionally known additives such as a lubricant, an antifoaming agent, a leveling agent, and a pigment can be added to the coating composition of the present invention in a known formulation.
• the coating composition of this invention can be used in the state which melt
• Organic solvents to be used include aromatic hydrocarbons such as toluene, xylene, and solvesso, esters such as ethyl acetate, butyl acetate, and dibasic acid esters, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone, and butyl cellosolve.
• Alcohol ethers such as butyl carbitol, alcohol ketones such as diacetone alcohol, alcohols such as isopropyl alcohol, n-butanol, amyl alcohol, n-hexanol, etc.
• Alcohol ethers such as butyl carbitol, alcohol ketones such as diacetone alcohol, alcohols such as isopropyl alcohol, n-butanol, amyl alcohol, n-hexanol, etc.
• it can also be made water-based by a conventionally known method and used as an aqueous coating composition.
• a basic compound such as ammonia or an organic amine compound, water, or further an organic solvent is added to form an aqueous coating composition.
• other resins are further used for the purpose of modifying the flexibility and adhesion of the coating film within the range that does not impair the excellent characteristics of the coating composition of the present invention. be able to.
• other resins include ethylene-polymerizable unsaturated carboxylic acid copolymers, ethylene-polymerizable carboxylic acid copolymer ionomers, non-aqueous polyester resins, and the like, and at least one resin selected from these resins. In some cases, the flexibility and adhesion of the coating film can be effectively imparted.
• the coated metal plate of the present invention can be obtained by coating the metal plate with the coating composition of the present invention.
• the metal plate that can be used include hot-drawn steel plate, cold-rolled steel plate, hot-dip galvanized steel plate, electrogalvanized steel plate, alloy-plated steel plate, aluminum zinc alloy-plated steel plate, aluminum plate, tin-plated steel plate, stainless steel plate, copper plate, copper Examples include plated steel sheets, tin-free steel, nickel-plated steel sheets, ultra-thin tin-plated steel sheets, chrome-treated steel sheets, and the like, and various surface treatments and primer treatments are used as necessary.
• the coated metal plate of the present invention can be obtained by coating the coating composition of the present invention on a metal plate by a known coating method such as roll coater coating or spray coating, and baking it by a heating means such as a coil oven.
• the coating composition of the present invention effectively suppresses the embrittlement of the cured coating film over time, so that it is baked at a high temperature in a short time, and is particularly effective when forming a coating film by coil baking, which tends to cause embrittlement over time.
• the thickness of the coating film is not particularly limited, but the dry film thickness is preferably in the range of 3 to 18 ⁇ m, more preferably 3 to 12 ⁇ m.
• the dry film thickness is appropriately determined depending on the use of the coated metal plate.
• the baking conditions of the coating film are appropriately adjusted depending on the polyester resin used, the type of crosslinking agent, the type of solvent used and the type of metal material to be coated, the thickness, the coating speed, and the like.
• the metal container of the present invention is formed by forming a coating film comprising the coating composition of the present invention on the inner surface and / or outer surface of the metal container, and the coating composition of the present invention is particularly excellent in corrosion resistance, flavor properties, etc. Therefore, it is desirable that a coating film made of the coating composition of the present invention is formed on at least the inner surface of the metal container.
• a metal container which forms a coating film all conventionally well-known metal containers can be used, However, It is not limited to this, The three-piece can which has a side seam, a seamless can (two-piece can) etc. can be mentioned.
• the metal container of the present invention can be molded from the above-mentioned painted metal plate. However, in the case of a metal container formed by harsh processing such as a seamless can, the present invention is applied to a pre-formed metal container. It is also possible to mold by applying the coating composition.
• the metal lid of the present invention can be formed from the above-described coated metal plate of the present invention by any conventionally known lid-making method. Generally, it is formed as a stay-on-tab type easy open can lid or a full open type easy open can lid.
• Polyester 0.2g was melt
• Initial workability Evaluated within 8 hours after preparing test coated plates.
• Processability over time Evaluated in the same manner as the initial processing after storage for 1 month in a constant temperature room at 40 ° C. within 8 hours after preparing the test coated plate.
• the evaluation criteria are as follows. ⁇ : Less than 0.5 mA ⁇ : 0.5 mA or more and less than 1.0 mA ⁇ : 1.0 mA or more and less than 3 mA ⁇ : 3 mA or more
• the test coating plate was immersed in water and treated for whitening at 125 ° C. for 30 minutes in an autoclave to evaluate the whitening property.
• Whitening property The whitening state of the coating film was visually evaluated. ⁇ : No whitening ⁇ : Slightly whitening ⁇ : Slightly whitening ⁇ : Remarkably whitening
• polyester resin (A) -a Dimethyl terephthalic acid 446 parts, trimellitic acid 2.2 parts, ethylene glycol 57 parts, propylene glycol 246 parts, 1,4-cyclohexanedimethanol 66 parts, titanium tetrabutoxide 0.2 part were charged into a 3 L four-necked flask, Assemble the polymerization equipment. The temperature was gradually raised to 220 ° C. over 4 hours to perform transesterification. This was subjected to initial polymerization under reduced pressure to 10 mmHg over 30 minutes and the temperature was raised to 250 ° C., and then the latter polymerization was performed for 90 minutes at 1 mmHg or less.
• polyester resin (B) -a 106 parts terephthalic acid, 225 parts isophthalic acid, 4 parts trimellitic anhydride, 143 parts 2-methyl-1,3-propanediol, 86 parts 1,4-butanediol, 92 parts 1,4-cyclohexanedimethanol, titanium tetrabutoxy 0.13 part was charged into a 2 L four-necked flask, and the temperature was gradually raised to 220 ° C. over 4 hours, and water was distilled off for esterification.
• the initial polymerization under reduced pressure was performed to 10 mmHg over 30 minutes and the temperature was raised to 250 ° C., and the latter polymerization was further performed at 1 mmHg or less for 50 minutes to stop the vacuum polymerization, Was taken out to obtain a polyester resin (B) -a of the present invention.
• Table 2 shows Tg, acid value, and number average molecular weight.
• the carboxylic acid anhydride is essential, the polyester resin (A)-having the acid values and Tg shown in Tables 1 and 2 is changed by changing the amount thereof and changing the type or amount of other monomers. b to (A) -i were prepared. Further, polyester resins (B) -b to (B) -g having acid values and Tg shown in Tables 1 and 2 were prepared by changing the types or amounts of the monomers.
• polyester resin (A), polyester resin (B), and solvent were placed in Kolben and heated, and dissolved with good stirring at 100 ° C. or lower. After completely dissolving, the polyester resin solution was cooled to room temperature, and a predetermined cross-linking agent and a curing catalyst were added while stirring well to prepare a coating composition.
• the crosslinker was Sumitrite Durez Co., Ltd. Sumitrite Resin PR-53893A (m-cresol resol type phenol resin) and Nippon Cytec Industries, Ltd. Mycoat 506 (Butylated Melamine Resin), and the curing catalyst was Nippon Cytec Industries. Cycat 602 (amine blocked dodecylbenzene sulfonic acid) manufactured by Co., Ltd. was used. A painted metal plate and a painted metal lid were prepared from each coating composition and evaluated. The results are shown in Tables 3 and 4.
• the coating composition of the present invention is excellent in all film properties such as processability, resistance to embrittlement over time, corrosion resistance, abrasion resistance, blocking resistance, retort resistance, etc. It can be suitably used for a coated metal plate that is baked in a coil oven, where embrittlement with time occurs remarkably.
• the coated metal plate having a coating film from the coating composition of the present invention is excellent in workability, resistance to embrittlement with time, wear resistance, and blocking resistance, and is subjected to severe processing. Can be suitably used for molding.
• the metal container or metal lid of the present invention has excellent corrosion resistance, retort resistance, and flavor, it is suitably used for metal containers that store corrosive contents or contents that require retort sterilization. be able to.

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