JP2014234450A - Aqueous coating agent and coating film consisting of the same as well as laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating agent capable of forming a coating film excellent in terms of adhesiveness to a metal, in particular, and having favorable scratch resistance as well as water resistance and acid resistance under high-temperature conditions.SOLUTION: The provided aqueous coating agent is an aqueous coating agent including a polyester resin (A), a resol-type phenolic resin (B), a basic compound, and an aqueous medium. The polyester resin (A) includes at least 50 mol% of an aromatic dicarboxylic acid as a polybasic acid component and at least 20 mol% of a linear glycol possessing no side chains as a polyhydric alcohol component. The acid value is 5-40 mgKOH/g, and (A)/(B) is 95/5-30/70 (mass ratio). The polyester resin has a number-average molecular weight of at least 4,000 and a glass transition point or melting point of 40 to 100°C. The aqueous coating agent includes virtually no surfactant but includes a crosslinking agent.

Description

  The present invention relates to an aqueous coating agent capable of forming a coating film having good scratch resistance and water resistance and acid resistance under high temperature conditions.

  Conventionally, metals used in automobiles and building materials have a coating film with excellent water resistance and heat resistance on the metal surface to suppress rust and corrosion, and their characteristics are maintained for a long time. It was necessary to provide such performance.

  An aqueous coating agent made of a polyester resin has been suitably used as a coating agent that can form such a coating film and is suitable for the environment.

Patent Document 1 proposes an aqueous coating agent containing a polyester resin having a specific composition and a curing agent such as isocyanate, and discloses a coating film excellent in water resistance and solvent resistance.
Patent Document 2 proposes an aqueous coating agent containing a polyester resin having a specific acid value and a resol type phenol resin, and further improves the water resistance and metal adhesion by using a crosslinking agent as necessary. A coating is disclosed.
Patent Document 3 proposes an aqueous coating agent containing a polyester resin having a specific molecular weight and a glass transition temperature and a resol type phenol resin, and can be suitably used in applications requiring strict processability and corrosion resistance. It is disclosed that there is.

JP 2001-288403 A

JP 2007-302786 A

JP 2000-204341 A

However, the aqueous coating agent compositions described in Patent Documents 1 to 3 can form a coating film having good solvent resistance and corrosion resistance, but are resistant to scratches, water resistance and acid resistance under high temperature conditions, etc. Was not necessarily enough.
An object of the present invention is to provide an aqueous coating agent that is particularly excellent in adhesion to a metal and that can form a coating film with good scratch resistance and water resistance and acid resistance under high temperature conditions.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.

That is, the gist of the present invention is as follows.
(1) A polyester resin (A), a resol type phenol resin (B), an aqueous coating agent containing a basic compound and an aqueous medium, wherein the polyester resin (A) is an aromatic dicarboxylic acid as a polybasic acid component 50 mol% or more, 20 mol% or more of a linear glycol having no side chain as a polyhydric alcohol component, an acid value of 5 to 40 mgKOH / g, and (A) / (B) of 95/5 A water-based coating agent, characterized in that it is -30/70 (mass ratio).
(2) The aqueous coating agent according to (1), wherein the polyester resin (A) has a number average molecular weight of 4000 or more.
(3) The aqueous coating agent according to (1) or (2), wherein the polyester resin (A) has a glass transition temperature or a melting point of 40 to 100 ° C.
(4) The aqueous coating agent according to any one of (1) to (3), wherein the aqueous coating agent does not substantially contain a surfactant component.
(5) The aqueous coating agent according to (1) to (4), further comprising a crosslinking agent.
(6) A coating film obtained by removing an aqueous medium from the aqueous coating agent of (1) to (5).
(7) A coated metal formed by forming the coating film of (6).
(8) The coated metal plate-like body in which the coated metal of (7) is a plate-like body and a coating film is formed on at least one surface of the plate-like body.
(9) A laminated body obtained by further bonding an adherend to the coated film surface in the coated metal plate-like body according to (8).

  According to the present invention, it is possible to obtain an aqueous coating agent that is particularly excellent in adhesion to a metal and that can form a coating film with good scratch resistance and water resistance and acid resistance under high temperature conditions.

  The present invention will be described in detail below.

  The coating agent of the present invention is an aqueous coating agent containing a polyester resin (A), a resol type phenol resin (B), a basic compound and an aqueous medium.

  The polyester resin (A) used in the present invention contains a polybasic acid component and a polyhydric alcohol component as main components.

  As a polybasic acid component which comprises a polyester resin (A), it is necessary to contain aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 3-tert-butylisophthalic acid, diphenic acid, and the like.

  In 100 mol% of the polybasic acid component constituting the polyester resin (A), the aromatic dicarboxylic acid must be contained in an amount of 50 mol% or more, preferably 60 mol% or more, and preferably 70 mol%. More preferably, it is more preferable to contain 80 mol%. When the content ratio of the aromatic dicarboxylic acid component is less than 50 mol%, the scratch resistance of the resulting coating film becomes poor.

  Polybasic acid components that can be contained in addition to the aromatic dicarboxylic acid include, for example, oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, aicosanedioic acid, hydrogenated dimer acid Saturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, dimer acid, and the like, 1,4-cyclohexanedicarboxylic acid 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornene dicarboxylic acid and its anhydride, tetrahydrophthalic acid and its anhydride, and the like, trimellitic acid, benzophenone tetra Carboxylic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride 3 or more functional groups such as acid, benzophenone anhydride tetracarboxylic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), 1,2,3,4-butanetetracarboxylic acid A carboxylic acid etc. are mentioned.

  When using a tribasic or higher polybasic acid as the polybasic acid component, it is preferably 5 mol% or less and preferably 4 mol% or less in 100 mol% of the polybasic acid component of the polyester resin (A). More preferably, it is more preferably 3 mol% or less.

  As the polybasic acid component, a polybasic acid having a sulfonic acid group can be used as necessary. Examples of such polybasic acids include 5-sodium sulfoisophthalic acid (SIPA-Na), 5-sodium sulfoterephthalic acid (STPA-Na), dimethyl 5-sodium sulfoisophthalate (SIPM-Na), 5- Examples thereof include dimethyl sodium sulfoterephthalate (STPM-Na), dimethyl 5-potassium sulfoisophthalate (SIMM-K), dimethyl 5-lithium sulfoisophthalate (SIMM-Li), and the like. Since excessive use of such a polybasic acid impairs the water resistance of the resulting coating film, in the present invention, sulfonic acid is contained in 100 mol% of the polybasic acid component constituting the polyester resin (A). The polybasic acid having a group is preferably less than 1 mol%, more preferably less than 0.5 mol%, and even more preferably 0 mol%.

  These polybasic acid components can be used alone or in combination of two or more.

  As a polyhydric alcohol component which comprises a polyester resin (A), it is necessary to contain the linear glycol which does not have a side chain. Examples of the linear glycol having no side chain include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonane. Examples include aliphatic glycols such as diols, diethylene glycol, triethylene glycol, dipropylene glycol, polytetramethylene glycol, polyethylene glycol, and polypropylene glycol-containing glycols such as polypropylene glycol.

  In 100 mol% of the polyhydric alcohol component constituting the polyester resin (A), the linear glycol having no side chain needs to be contained in an amount of 20 mol% or more, preferably 30 mol% or more. More preferably, it is more than mol%, and still more preferably more than 50 mol%. When the content of the linear glycol having no side chain is less than 20 mol%, the resulting coating film has poor acid resistance.

  Examples of the polyhydric alcohol component other than the polyhydric alcohol include 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol. , Aliphatic glycols having side chains such as 2-ethyl-2-butylpropanediol, alicyclic glycols such as 1,4-cyclohexanedimethanol, 1,3-cyclobutanedimethanol, glycerin, trimethylolethane, trimethylol Examples thereof include trifunctional or higher functional alcohols such as propane and pentaerythritol. Furthermore, alkylene oxide adducts of bisphenols such as 2,2-bis [4- (hydroxyethoxy) phenyl] propane and bis [4- (hydroxyethoxy) phenyl] sulfone can also be used. Care must be taken because the weather resistance of the coating film may be poor.

  In the case of using a trifunctional or higher polyhydric alcohol as the polyhydric alcohol component, it is preferably 5 mol% or less, preferably 4 mol% or less in 100 mol% of the polyhydric alcohol component of the polyester resin (A). More preferably, it is more preferably 3 mol% or less.

  These polyhydric alcohol components can be used alone or in combination of two or more.

  The polyester resin (A) can contain a monocarboxylic acid and a monoalcohol as long as the characteristics of the present invention are not impaired. The use of an excess of such a monocarboxylic acid and monoalcohol will be described later. When the polyester resin (A) is produced, the extension of the molecular chain is inhibited, the polycondensation does not proceed, and as a result, the necessary molecular weight cannot be obtained, and the adhesion of the coating film is insufficient. In the present invention, the monocarboxylic acid or monoalcohol is preferably less than 1 mol% in 100 mol% of the polybasic acid component or 100 mol% of the polyhydric alcohol component constituting the polyester resin (A). More preferably, it is less than 1 mol%, and more preferably 0 mol%.

  The acid value of the polyester resin (A) needs to be 5 to 40 mgKOH / g, preferably 5 to 35 mgKOH / g, more preferably 5 to 30 mgKOH / g, and 5 to 25 mgKOH / g. More preferably, it is most preferably 5 to 20 mg KOH / g. If the acid value exceeds 40 mgKOH / g, the resulting coating film has insufficient water resistance, and if it is less than 5 mgKOH / g, it is difficult to disperse the polyester resin in the aqueous medium, and a uniform and stable aqueous coating agent is obtained. It becomes difficult.

  The number average molecular weight of the polyester resin (A) is preferably 4000 or more, more preferably 9000 or more, and further preferably 12000 or more, from the viewpoint of improving adhesion at high temperatures. When the number average molecular weight is less than 4000, the resulting coating film tends to have insufficient water resistance and the processability of the coating film tends to be insufficient.

  In addition, the number average molecular weight is preferably 45000 or less, more preferably 40000 or less, and particularly preferably 35000 or less from the viewpoint of easily imparting a sufficient acid value to the polyester resin (A).

  When the glass transition temperature (hereinafter abbreviated as Tg) or the melting point (hereinafter abbreviated as Tm) of the polyester resin (A) is 40 to 100 ° C., the adhesiveness when used as a coating film is improved. It is preferable from the point which is easy to improve, It is more preferable that it is 50-100 degreeC, It is further more preferable that it is 60-100 degreeC. For example, in the case of a polyester resin having only Tg without Tm, Tg is preferably 40 to 100 ° C. In the case of a polyester resin having Tg and Tm, it is preferable that both are in the range of 40 to 100 ° C, or either Tg or Tm is in the range of 40 to 100 ° C.

  The resol type phenol resin (B) in the present invention is one of methylol groups of a methylolated phenol resin obtained by introducing a methylol group by heating and condensing a phenol component and formaldehyde in the presence of a reaction catalyst. Part is formed by alkyl etherification with alcohol.

  Examples of the phenol component of the resol type phenol resin (B) include trifunctional phenols such as phenol, m-cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol, and the like. , Or a mixture of two or more.

  In addition to the above phenol component, 50 mass% or less in the whole phenol component, such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, etc. It may contain phenol or the like.

  Examples of the formaldehydes used in the production of the resol type phenolic resin (B) include formaldehyde, paraformaldehyde, trioxane and the like, and they can be used alone or in combination of two or more.

  As the alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin, a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, can be suitably used. Suitable monohydric alcohols include methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.

  Commercially available resol-type phenol resins can be used. For example, PL series (PL-2773, PL-5634, PL-6757, etc.) manufactured by Gunei Chemical Co., Ltd., Phenolite manufactured by Dainippon Ink & Chemicals, Inc. And PE series (PE-602, TD-4304, etc.). In addition, although the property of a resol type phenol resin is not specifically limited, Aqueous solution type and an emulsion type can be used.

  In the present invention, the ratio of the polyester resin (A) to the resol type phenol resin (B) needs to be 95/5 to 30/70 (mass ratio), and 90/10 to 50/50 (mass ratio). Is preferred, 85/15 to 50/50 (mass ratio) is more preferred, and 80/20 to 60/40 (mass ratio) is particularly preferred. When the ratio of a phenol resin (B) is less than 5 mass%, since the crosslinking density is low, the adhesiveness of the coating film obtained falls and acid resistance is also inferior. On the other hand, when it exceeds 70 mass%, the adhesiveness of the coating film obtained when a crosslinking density becomes high too much falls.

  The aqueous coating agent of the present invention can further improve the curability of the resulting coating film by blending an acid catalyst. As the acid catalyst, an acid catalyst neutralized with an organic amine compound is preferable from the viewpoint of improving curability, and examples of the acid species include p-toluenesulfonic acid and dodecylbenzenesulfonic acid. The compounding amount of the acid catalyst is determined based on the physical properties of the resulting coating film, etc., and the amount of acid (for example, in the case of an amine neutralized product of a sulfonic acid compound, the amount of the remaining sulfonic acid compound from which the amine has been removed. ) With respect to 100 parts by mass of the polyester resin (A), 0.01 to 5 parts by mass, preferably 0.1 to 2 parts by mass.

  The aqueous coating agent of the present invention contains a basic compound, and the carboxyl group in the polyester resin (A) is neutralized by the basic compound, and the electric repulsive force between the anions generated by the neutralization makes it possible to generate fine particles. Aggregation is prevented and stability is imparted to the aqueous coating agent. The addition amount of the basic compound is preferably 0.5 to 3.0 times equivalent, more preferably 0.8 to 2.5 times equivalent to the acid value (carboxyl group) of the polyester resin (A). 1.0-2.0 times equivalent is particularly preferable. When it exceeds 3.0 times equivalent, drying time at the time of coating film formation may become long.

  The basic compound added to the aqueous coating agent is not particularly limited as long as it can neutralize the carboxyl group. In addition to metal hydroxides such as LiOH, KOH, and NaOH, from the viewpoint of the water resistance of the coating film, compounds that volatilize during the formation of the coating film are preferable, and ammonia or various organic amine compounds are preferable. Specific examples of the organic amine compound include triethylamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, and 3-ethoxypropylamine. , 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, N-methylmorpholine, N- Examples thereof include ethyl morpholine. The boiling point of the organic amine compound is preferably 250 ° C. or lower. When it exceeds 250 ° C., it becomes difficult to disperse the organic amine compound from the formed coating film by drying, and the water resistance of the resulting coating film may be lowered.

  The aqueous coating agent of the present invention contains an aqueous medium. Here, the aqueous medium refers to water or a mixture of water and a water-soluble organic solvent. Specific examples of the water-soluble organic solvent include, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, alcohols such as tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, isophorone, Ethers such as tetrahydrofuran and dioxane, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-sec-butyl, acetic acid-3-methoxybutyl Esters such as methyl propionate, ethyl propionate, diethyl carbonate, dimethyl carbonate, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol , Glycol derivatives such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetate, and 3-methoxy-3-methylbutanol, 3-methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, and the like. Among the above organic solvents, methanol, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monoethyl ether are preferred because of their good drying properties at relatively low temperatures around room temperature. , Ethylene glycol monopropyl ether and ethylene glycol monobutyl ether are preferable, and methanol, ethanol, n-propanol and isopropanol are particularly preferable. These organic solvents may be used in combination of two or more. In the aqueous coating agent of the present invention, the basic compound described above may be contained in the aqueous medium.

  The aqueous coating agent of this invention can be manufactured using a well-known method. The simplest method is a method in which an aqueous dispersion containing a polyester resin (A) and an aqueous solution containing a resol type phenol resin (B) are mixed at a specific ratio. The aqueous dispersion containing the polyester resin (A) can be used by dispersing the polyester resin used as a raw material in an aqueous dispersion by a known method, but a commercially available aqueous dispersion may be used. In order to prevent the precipitation of the polyester resin when mixing the two, in order to improve the stability of the aqueous coating agent, a monovalent alcohol having 1 to 4 carbon atoms, such as methanol or ethanol. , N-propanol, isopropanol, n-butanol and isobutanol can be added in small amounts.

  In the aqueous coating agent of the present invention, the number average particle diameter of the polyester resin (A) particles is preferably 1 μm or less from the viewpoint of improving liquid stability, and has compatibility and reactivity with the resol type phenol resin (B). From the point of improving, 0.5 μm or less is more preferable, 0.3 μm or less is more preferable, and 0.1 μm or less is most preferable. Furthermore, the volume average particle diameter is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.2 μm or less. The lower limit of the particle diameter is not particularly limited, but the number average particle diameter and the volume average particle diameter are usually about 0.01 μm.

  The solid content concentration of the aqueous coating agent, that is, the total of the mass% of the polyester resin (A) and the mass% of the resol type phenolic resin (B) with respect to 100% by mass of the aqueous coating agent is the film forming conditions and the target coating film. It is suitably adjusted depending on the thickness, performance, etc., and is not particularly limited, but is preferably 1 to 60% by mass in order to keep the viscosity of the aqueous coating agent moderate and to exhibit good film forming ability. 5 to 55% by mass is more preferable, and 10 to 50% by mass is even more preferable.

  In the aqueous coating agent, the smaller the content of the surfactant component, the better the water resistance of the coating film obtained from the aqueous coating agent and the adhesion to the base material, and the smaller the change with time in adhesion after long-term storage. There are no hygiene problems. Therefore, the surfactant component is preferably 10 parts by mass or less with respect to 100 parts by mass in total of the polyester resin (A) and the resol type phenol resin (B) in the aqueous coating agent, and is 5 parts by mass or less. More preferably, it is most preferable not to contain substantially.

  The surfactant component in the present invention is a compound having a molecular weight of 300 or more and dissolved in water and contributing to the dispersion and stabilization of the resin, and includes a cationic surfactant, an anionic surfactant, and a nonion. (Nonionic) surfactants, amphoteric surfactants, fluorosurfactants, reactive surfactants, water-soluble polymers, and the like, and in addition to those generally used for emulsion polymerization, emulsifiers are also included . For example, anionic surfactants include sulfates of higher alcohols, higher alkyl sulfonic acids and salts thereof, alkyl benzene sulfonic acids and salts thereof, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfone salts. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide. -Propylene oxide copolymer, sorbitan derivatives such as polyoxyethylene sorbitan fatty acid ester, etc. It is lauryl betaine, lauryl dimethyl amine oxide, and the like. Examples of reactive surfactants include alkylpropenylphenol polyethylene oxide adducts and their sulfate esters, allyl alkylphenol polyethylene oxide adducts and their sulfate esters, allyl dialkylphenol polyethylene oxide adducts and their sulfate esters, etc. Examples thereof include compounds having a reactive double bond. Examples of the water-soluble polymer include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, modified starch, polyvinyl pyrrolidone, polyacrylic acid and salts thereof.

  In the aqueous coating agent of the present invention, in order to further improve various coating film performances such as water resistance and boil resistance, the crosslinking agent is added in an amount of 0.1 to 50 masses with respect to 100 mass parts of the resin in the aqueous coating agent. Part, preferably 0.5 to 30 parts by weight can be added. When the addition amount of the crosslinking agent is less than 0.1 parts by mass, the degree of improvement in coating film performance is small, and when it exceeds 50 parts by mass, the coating film performance such as liquid stability and workability of the aqueous coating agent is low. It will decline. As the crosslinking agent, a crosslinking agent having self-crosslinking property, a compound having a plurality of functional groups that react with a carboxyl group in the molecule, a metal complex having a polyvalent coordination site, etc. can be used. Of these, isocyanate compounds , A melamine compound, a urea compound, an epoxy compound, a carbodiimide compound, an oxazoline group-containing compound, an aziridine compound, a zirconium salt compound, a silane coupling agent, and the like are preferable. Moreover, you may use combining these crosslinking agents. To the aqueous coating agent of the present invention, other polymers, tackifying components and the like can be further added.

  The type of other polymer is not particularly limited. For example, polyolefin resin having a main skeleton of ethylene or propylene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, ethylene- (Meth) acrylic acid copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide resin, chlorinated polyethylene resin, chlorinated polypropylene resin , Modified nylon resin, urethane resin, silicone resin, epoxy resin and the like. You may use these in mixture of 2 or more types.

  As the tackifier component, for example, at least one component selected from rosins, terpenes, petroleum resins, coumarone resins, and indene resins can be used. As rosins, polymerized rosin, disproportionated rosin, hydrogenated rosin, maleated rosin, fumarated rosin, and glycerin ester, pentaerythritol ester, methyl ester, ethyl ester, butyl ester, ethylene glycol ester, diethylene glycol ester And triethylene glycol ester. Examples of terpenes include low-polymerized terpene, α-pinene polymer, β-pinene polymer, terpene phenol, aromatic modified terpene, and hydrogenated terpene. As petroleum resins, petroleum resins obtained by polymerizing petroleum fractions having 5 carbon atoms, petroleum resins obtained by polymerizing petroleum fractions having 9 carbon atoms, and petroleum resins obtained by hydrogenation of these, maleic acid-modified, phthalic acid-modified Examples include petroleum resin.

  In the aqueous coating agent of the present invention, various agents such as a leveling agent, an antifoaming agent, an anti-waxing agent, a pigment dispersant, and an ultraviolet absorber may be further added as long as the effects of the present invention are not impaired.

  Since the aqueous coating agent of the present invention is excellent in film forming ability, known film forming methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, Uniform coating on the surface of the metal plate by dip coating, brushing, etc., and setting it near room temperature as necessary, followed by heat treatment for drying or drying and baking. Can be formed in close contact with the substrate. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used. Further, the heating temperature and the heating time are appropriately selected depending on the characteristics of the base material, the kind of the curing agent, the blending amount, and the like, and are not particularly limited. .

  The aqueous coating agent can form a good coating film by removing the aqueous medium from the aqueous coating agent as described above.

  Although it does not specifically limit as a metal which can form the coating film of an aqueous coating agent, It is preferable to use for iron, stainless steel, copper, aluminum, etc. The metal may be a block or a plate. When the metal is a plate-like body, the coating film may be formed on one side or on both sides.

  The thickness of the coating film formed by removing the aqueous medium from the aqueous coating agent of the present invention is not particularly limited, but is preferably 0.05 to 100 μm, and more preferably 0.5 to 10 μm. When the thickness is less than 0.05 μm, the adhesiveness is low, and when it exceeds 100 μm, the drying time is long.

  When the coating film is formed on a plate-like, sheet-like, or film-like substrate, an adherend can be bonded to the formed coating film surface to form a laminate. As the adherend, for example, paper, synthetic paper, various thermoplastic films and molded bodies, glass, metal, and the like can be used. Among these, in order to make use of the adhesive characteristics of the aqueous coating agent of the present invention, a laminate such as metal material / coating film of the present invention / vinyl chloride material, metal material / coating film of the present invention / polyester resin material, etc. It can be used in the form of metal material / coating of the present invention / various top coats. The obtained coated metal and laminate can be used for various industrial applications and food applications. In particular, it is suitable for edible cans, beverage cans, pail cans for chemical storage, embossed decorating materials, etc. by utilizing the properties of adhesion, acid resistance and scratch resistance.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

(1) Composition of polyester resin The resin composition was calculated | required from the peak intensity | strength of each copolymerization component by performing < ¹ > H-NMR analysis using the high-resolution nuclear magnetic resonance apparatus (JEOL Co., Ltd. ECA500 type NMR).
・ Resolution: 500MHz
Solvent: Deuterated trifluoroacetic acid Temperature: 25 ° C
In addition, with respect to a resin containing a constituent monomer in which no assignable / quantifiable peak is observed on the ¹ H-NMR spectrum, it is subjected to methanol decomposition at 230 ° C. for 3 hours in a sealed tube, followed by gas chromatogram analysis for quantitative analysis. I did it.

(2) Acid value of polyester resin 0.5 g of polyester resin was dissolved in 50 ml of water / dioxane = 10/1 (volume ratio), titrated with KOH using cresol red as an indicator, and the amount of KOH consumed for neutralization. A value obtained by converting the number of mg per 1 g of the polyester resin was determined as an acid value.

(3) Number average molecular weight of polyester resin The number average molecular weight was determined by polystyrene conversion by GPC analysis using the following apparatus and conditions.
・ Liquid feeding unit (LC-10ADvp type, manufactured by Shimadzu Corporation)
・ Ultraviolet-visible spectrophotometer (SPD-6AV type manufactured by Shimadzu Corporation)
・ Detection wavelength: 254 nm
・ Solvent: Tetrahydrofuran

(4) Glass transition temperature and melting point of polyester resin 10 mg of the polyester resin was weighed and increased using an input-compensated differential scanning calorimeter (Diamond type DSC manufactured by PerkinElmer, detection range: −50 ° C. to 200 ° C.). Measurement is performed at a temperature rate of 10 ° C / min, and the slope of the curve of the step-like change portion of the glass transition is maximized in the temperature rise curve obtained by extending the low-temperature base line to the high-temperature side. The temperature at the intersection with the tangent drawn at such a point was determined and used as the glass transition temperature.
Further, 10 mg of the polyester resin was weighed, and the temperature was raised from −50 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min. Of melting point.

(5) Volume average particle diameter, number average particle diameter It is diluted with water so that the concentration of the resin in the aqueous coating agent becomes 0.1% by mass, and a laser diffraction particle diameter measuring apparatus (MICROTRAC UPA (model by Nikkiso Co., Ltd.)) 9340-UPA type)), volume average particle diameter and number average particle diameter were measured.
The refractive index of the polyester resin was 1.57, and the density of the polyester resin was 1.21 g / cm ³ .

(6) Water resistance evaluation method of coating film After coating with a Mayer bar on a SUS plate (made of stainless steel, thickness 1.5 mm) with an aqueous coating agent so that the coating thickness after drying becomes 10 μm, 90 ° C. And for 5 minutes, the curing reaction was carried out at 200 ° C. for 5 minutes. Thereafter, the obtained coated metal plate was immersed in boiling water at 95 ° C. for 2 hours, and the state of the coating film after air drying was visually evaluated.

○: No change Δ: The coating film is cloudy ×: The coating film is completely dissolved or peeled off

(7) Evaluation of substrate / coating layer adhesion (cross-cut / tape peeling)
Using the laminate obtained in the same manner as in (6), the evaluation was made according to JIS K5400 8.5.2. The grid area of 1 mm × 1 mm × 100 pieces was peeled off with an adhesive tape and evaluated by the number remaining without peeling. “N / 100” indicates that n of the 100 grids remain without being peeled after the test.
In the present invention, the range of “100/100” to “95/100” is acceptable. Here, “100/100” means that no peeling of the coating film occurs, and is most excellent.

(8) Evaluation was made according to JIS K5600-6-1 using a laminate obtained in the same manner as in the acid resistance evaluation method (6) of the coating film. A few drops of a 5 g / L sulfuric acid aqueous solution was dropped on the surface of the coating film, the droplets were covered with a hard vinyl chloride tube to prevent excessive drying, and the glass plate was covered. After standing for 3 days in a 50 ° C. atmosphere, the droplets were washed with running water, and the state of the coating film was visually evaluated.
○: No change Δ: Slight coating roughness is observed ×: The coating is discolored, deformed, or peeled off from the substrate

(9) Method for evaluating hardness of coating film Using the laminate obtained in the same manner as in (6), evaluation was performed according to JIS K5600-5-4. Scratching with pencils with various hardness ("UNI" series, manufactured by Mitsubishi Pencil Co., Ltd.) If it becomes “Accepted”, the hardness scale is raised and the coating film is damaged. If the tip of the pencil reaches the substrate, the hardness scale is lowered as “Fail” and the hardest pencil that passes is accepted. Was the hardness of the coating film.
In the present invention, those having a hardness of HB or higher are determined to be practical, H or higher is more preferable, and 2H or higher is more preferable.

[Preparation of polyester resin]
By the procedures of Preparation Examples 1 to 9, polyester resins (a1) to (a9) used in Examples and Comparative Examples were obtained.

Preparation Example 1
A mixture of 1163 g of terephthalic acid, 1412 g of isophthalic acid, 1920 g of sebacic acid, and 2740 g of 1,4-butanediol was heated in an autoclave at 220 ° C. for 4 hours to carry out an esterification reaction. At this time, the monomer components were blended with terephthalic acid: isophthalic acid: sebacic acid: 1,4-butanediol = 28: 34: 38: 122 (molar ratio). Next, 2.6 g of tetrabutyl titanate (3 × 10 ⁻⁴ mol per 1 mol total of all acid components) was added as a catalyst, and then the temperature of the system was raised to 230 ° C., and the pressure of the system was gradually reduced. The pressure was 13 Pa after 1.5 hours. Under this condition, the polycondensation reaction was continued, and after 4 hours, the system was brought to atmospheric pressure with nitrogen gas, the temperature of the system was lowered, and when the temperature reached 220 ° C., 47 g of trimellitic acid (0 per mole of total acid components in total) 0.006 mol) was added and the mixture was stirred at 220 ° C. for 2 hours to carry out a depolymerization reaction. Thereafter, the system was pressurized with nitrogen gas and discharged into a sheet. This was cooled to room temperature to obtain a sheet-like polyester resin (a1).

Preparation Examples 2-9
Polyester resins (a2) to (a9) were obtained in the same manner as the polyester resin (a1) except that the charging composition was changed as shown in Table 1. Polyester resins (a2), (a4), (a7), and (a9) were discharged into a sheet and allowed to cool, then crushed with a crusher, and a fraction having an opening of 1 to 6 mm was collected using a sieve, and granular. A polyester resin was obtained. Polyester resins (a3), (a5), (a6), and (a8) were discharged in the form of strands, cut with water, and cut into pellets having a diameter of about 3 mm and a length of about 3 mm.

In Table 1, abbreviations indicate the following.
TPA: terephthalic acid IPA: isophthalic acid SEA: sebacic acid EG: ethylene glycol 1,4-BD: 1,4-butanediol NPG: neopentyl glycol 1,2-PD: 1,2-propanediol TMA: trimellitic acid

  Table 2 shows the final resin compositions and characteristic values of the obtained polyester resins (a1) to (a9).

[Preparation of polyester resin dispersion]
Preparation Example 10
Using a jacketed cylindrical glass container (with an internal volume of 3 L) and a stirrer (manufactured by Tokyo Science Instrument Co., Ltd., “MAZELA NZ-1200”), 300 g of polyester resin (a1) and 180 g of n-propanol , 9.5 g of triethylamine (corresponding to 1.2 times equivalent of triethylamine with respect to the acid value of the polyester resin) and 510 g of distilled water were each put in a glass container, and the stirring blade was kept at a rotational speed of 70 rpm while stirring. The temperature was raised through hot water in the jacket. When the internal temperature reached 80 ° C., the temperature was raised and stirring was continued for 120 minutes. During stirring, the internal temperature was kept at 82 ± 2 ° C. Thereafter, cold water was passed through the jacket, and the rotational speed was lowered to 30 rpm and the mixture was stirred and cooled to 25 ° C. to obtain an aqueous polyester resin coating agent. The obtained aqueous coating agent was filtered with a 600 mesh stainless steel filter to obtain a polyester resin dispersion (A-1).

Preparation Example 11
The polyester resin (a2) is 300 g, isopropanol is 220 g, triethylamine is 11.9 g (1.0 times equivalent to the acid value of the polyester resin (a2)), and ion-exchanged water is 468 g. Preparation similar to resin dispersion (A-1) was performed, and polyester resin dispersion (A-2) was obtained.

Preparation Example 12
Other than using 300 g of polyester resin (a3), 200 g of n-propanol, 6.5 g of triethylamine (2.0 times equivalent to the acid value of polyester resin (a3)), and 494 g of ion-exchanged water as raw materials. The same preparation as that of the polyester resin dispersion (A-1) was performed to obtain a dispersion. In addition, 800 g of the obtained contents were charged into a round bottom flask, 400 g of ion exchange water was charged, a mechanical stirrer and a Liebig condenser were installed, the flask was heated in an oil bath, and 400 g of an aqueous medium was distilled at normal pressure. Left. Thereafter, the mixture was cooled to room temperature, and further stirred, 0.9 g of 28% by mass ammonia water was added to obtain a polyester resin dispersion (A-3).

Preparation Example 13
The polyester resin (a4) is 300 g, isopropanol is 180 g, triethylamine is 24.7 g (1.2 times equivalent to the acid value of the polyester resin (a4)), and ion-exchanged water is 495 g. Preparation similar to resin dispersion (A-1) was performed, and polyester resin dispersion (A-4) was obtained.

Preparation Example 14
Other than using 300 g of polyester resin (a5), 200 g of n-propanol, 7.6 g of triethylamine (2.0 times equivalent to the acid value of polyester resin (a5)), and 492 g of ion-exchanged water as raw materials. The same preparation as that of the polyester resin dispersion (A-1) was performed to obtain a dispersion. In addition, 800 g of the obtained contents were charged into a round bottom flask, 400 g of ion exchange water was charged, a mechanical stirrer and a Liebig condenser were installed, the flask was heated in an oil bath, and 400 g of an aqueous medium was distilled at normal pressure. Left. Thereafter, the mixture was cooled to room temperature, and 0.9 g of 28% by mass ammonia water was added while stirring to obtain a polyester resin dispersion (A-5).

Preparation Example 15
Other than using 300 g of polyester resin (a6), 200 g of n-propanol, 8.7 g of triethylamine (2.0 times equivalent to the acid value of polyester resin (a6)), and 491 g of ion-exchanged water as raw materials. The polyester resin dispersion (A-3) was prepared in the same manner as in the polyester resin dispersion (A-1).

Preparation Example 16
The polyester resin (a7) is 300 g, the isopropanol is 220 g, the triethylamine is 10.8 g (1.0 times equivalent to the acid value of the polyester resin (a7)), and the ion-exchanged water is 469 g. Preparation similar to resin dispersion (A-1) was performed, and polyester resin dispersion (A-7) was obtained.

Preparation Example 17
Polyester resin dispersion except that the polyester resin (a8) is 300 g, n-propanol is 200 g, triethylamine is 10.8 g (20 times equivalent to the acid value of the polyester resin (a8)), and ion-exchanged water is 489 g. Preparation similar to body (A-1) was performed, and polyester resin dispersion (A-8) was obtained. However, since the obtained polyester resin dispersion (A-8) was solidified immediately after completion of the solvent removal step, the subsequent evaluation could not be performed.

Preparation Example 18
The polyester resin (a9) is 300 g, the isopropanol is 180 g, the triethylamine is 28.6 g (1.2 times equivalent to the acid value of the polyester resin (a9)), and the ion-exchanged water is 491 g. Preparation similar to resin dispersion (A-1) was performed, and polyester resin dispersion (A-9) was obtained.

  Table 3 shows the characteristic values of the obtained polyester resin dispersions (A-1) to (A-9).

Example 1
100 parts by mass of the polyester resin dispersion (A-1), 28.6 parts by mass of a resol-type phenol resin aqueous solution (manufactured by Gunei Chemical Co., Ltd., PL-5634, solid content concentration 45% by mass) and 28.6 parts by mass of n-propyl alcohol The parts were mixed and stirred at room temperature for 5 minutes so that the ratio of polyester resin / phenol resin = 70/30 (mass ratio) was obtained to obtain an aqueous coating agent, and various performance evaluations were performed.

Examples 2-5
An aqueous coating agent was obtained in the same manner as in Example 1 except that the polyester resin dispersion was changed to (A-2) to (A-5), respectively. Various performance evaluations were performed using these aqueous coating agents.

Example 6
100 parts by mass of polyester resin dispersion (A-3), 7.4 parts by mass of resol type phenol resin aqueous solution (manufactured by Gunei Chemical Co., Ltd., PL-5634, solid content concentration 45% by mass) and 7.4 parts by mass of n-propyl alcohol The parts were mixed and stirred at room temperature for 5 minutes so that the ratio of polyester resin / phenol resin = 90/10 (mass ratio) was obtained to obtain an aqueous coating agent, and various performance evaluations were performed.

Example 7
100 mass parts of polyester resin dispersion (A-3), resol type phenol resin aqueous solution (manufactured by Gunei Chemical Co., Ltd., PL-5634, solid content concentration 45 mass%) 66.5 mass parts and n-propyl alcohol 66.5 mass The parts were mixed and stirred at room temperature for 5 minutes so that the ratio of polyester resin / phenol resin = 50/50 (mass ratio) was obtained to obtain an aqueous coating agent, and various performance evaluations were performed.

Example 8
Polyester resin dispersion (A-3) 100 parts by mass, resol type phenol resin aqueous solution (manufactured by Gunei Chemical Co., Ltd., PL-5634, solid content concentration 45% by mass) 123 parts by mass and n-propyl alcohol 123 parts by mass Mixing and stirring were performed at room temperature for 5 minutes to obtain resin / phenolic resin = 35/65 (mass ratio) to obtain an aqueous coating agent, and various performance evaluations were performed.

Example 9
A polyfunctional isocyanate compound (manufactured by Sumitomo Bayer Urethane Co., Ltd., Bihydur 3100, isocyanate group content: about 17% by mass, solid content concentration of 100% by mass) is further added to the aqueous coating agent obtained in Example 3 as a crosslinking agent. And resol type phenol resin were added so as to be 5 parts by mass with respect to 100 parts by mass of the total solid content. Various performance evaluation was performed using the obtained aqueous coating agent.

Comparative Examples 1-3
An aqueous coating agent was obtained in the same manner as in Example 1 except that the polyester resin dispersion was changed to (A-6), (A-7), and (A-9), respectively. Various performance evaluations were performed using each aqueous coating agent.

Comparative Example 4
Various performance evaluations were performed using only the polyester resin dispersion used in Example 3.

Comparative Example 5
100 parts by mass of polyester resin dispersion (A-3), 201 parts by mass of resol type phenol resin aqueous solution (manufactured by Gunei Chemical Co., Ltd., PL-5634, solid content concentration 45% by mass) and 201 parts by mass of n-propyl alcohol were mixed with polyester. Mixing and stirring were performed at room temperature for 5 minutes to obtain resin / phenolic resin = 25/75 (mass ratio) to obtain an aqueous coating agent, and various performance evaluations were performed.

Comparative Example 6
Instead of using a resol-type phenol resin, a polyfunctional isocyanate compound (manufactured by Sumitomo Bayer Urethane Co., Ltd., Bihijoule 3100, isocyanate group content: about 17% by mass, solid content concentration 100% by mass) is used as a cross-linking agent. 10 mass parts was added with respect to the mass part. Various performance evaluation was performed using the obtained aqueous coating agent.

  The evaluation results of various performances are summarized in Table 4 and Table 5.

  In Examples 1-9, the coating film excellent in adhesiveness with a metal, scratch resistance, water resistance under high temperature conditions, and acid resistance could be obtained.

  In Comparative Example 1, the constituent polybasic acid component was less than 50 mol% of the aromatic dicarboxylic acid, so that the scratch resistance of the coating film was inferior.

  In Comparative Example 2, the acid resistance of the coating film was inferior because the polyhydric alcohol component was less than 20 mol% of linear glycol having no side chain.

  In Comparative Example 3, since the acid value of the polyester resin exceeded 40 mgKOH / g, the water resistance of the coating film was inferior.

  In Comparative Example 4, since no resol type phenolic resin was contained, the adhesion and acid resistance of the coating film were inferior.

  In Comparative Example 5, since the ratio of the resol type phenol resin exceeded 70% by mass, the adhesion of the coating film was inferior.

In Comparative Example 6, since the polyfunctional isocyanate compound was used instead of the resol type phenol resin, the acid resistance of the coating film was inferior.

Claims (9)

  A polyester resin (A), a resol type phenol resin (B), an aqueous coating agent containing a basic compound and an aqueous medium, wherein the polyester resin (A) contains 50 mol of an aromatic dicarboxylic acid as a polybasic acid component. %, Containing 20 mol% or more of a linear glycol having no side chain as a polyhydric alcohol component, an acid value of 5 to 40 mg KOH / g, and (A) / (B) of 95/5 to 30 / An aqueous coating agent characterized by being 70 (mass ratio).   The aqueous coating agent according to claim 1, wherein the number average molecular weight of the polyester resin (A) is 4000 or more.   The aqueous coating agent according to claim 1 or 2, wherein the polyester resin (A) has a glass transition temperature or a melting point of 40 to 100 ° C.   The aqueous coating agent according to any one of claims 1 to 3, wherein the aqueous coating agent does not substantially contain a surfactant component.   Furthermore, a crosslinking agent is contained, The aqueous coating agent in any one of Claims 1-4 characterized by the above-mentioned.   A coating film obtained by removing an aqueous medium from the aqueous coating agent according to claim 1.   A coated metal obtained by forming the coating film according to claim 6.   The coated metal plate-like body, wherein the coated metal according to claim 7 is a plate-like body, and a coating film is formed on at least one surface of the plate-like body. The laminated metal plate-like body according to claim 8, wherein an adherend is further bonded on the coating film surface.