JP5958211B2 - Water-based paint for metal packaging materials and metal packaging materials - Google Patents

Description

  The present invention relates to a water-based paint for a metal packaging material and a metal packaging material, and relates to a water-based paint suitably used for coating a metal material directly or on a base paint.

Metal cans that contain beverages and foods are printed and painted in advance on metal plates, and then various molding processes (drawing, punching, winding, folding, etc.) , Collectively referred to as can making). In particular, the can lid part is manufactured through a multi-stage molding process after coating a metal plate with paint, and the process of attaching tabs and the like (the process after painting is collectively referred to as the lid making process) ).
For this reason, since a large physical load is applied to the coating film in the lid making process, the coating film may be peeled off from the base metal or the coating film may be lost (the coating film may be missing). In particular, on the outer surface side of the can lid, not only the coating film defect occurs in the vicinity of the outer periphery of the lid, but also the base metal as the base material is sometimes scraped (this phenomenon is called cut edge rough). Furthermore, when the scraped metal powder adheres to the mold part of the lid making machine, a lid making failure occurs, and continuous lid making becomes difficult.

  In addition, when the lid is continuously formed, there is often a problem that the wax component existing on the outermost surface of the coating film is deposited on the mold portion of the lid making machine (this phenomenon is called wax deposition). In this case, the wax deposited on the lid that has been made may retransfer, or the dimensions of the lid may change due to the deposited wax, making the lid itself difficult.

  In general, painting of the can lid portion is often performed by so-called coil coating, in which a paint is continuously applied to a coiled iron plate or aluminum plate (including an aluminum alloy plate) and baked. Conventionally, coating lines have been sped up to reduce manufacturing costs. The coating method is a reverse coating method in which the applicator roll rotates in the reverse direction with respect to the flow direction of the metal plate. It is used. In recent years, as the line speed increases further, baking is performed in a coating baking process at a higher temperature and in a shorter time than before, which causes the problem of coating defects. It is like that.

  The coating defects in the reverse coating method include “unevenness” caused by poor paint pick-up and poor transfer between rolls during painting, and “roll eyes” caused by the transition of the rib pattern of the paint generated between rolls to the metal plate. `` Waki '' that cures while leaving traces of foam remaining on the surface when the coating is baked, and `` Repel '' derived from the non-uniformity of the paint components, etc. A coating defect occurs when the viscosity characteristics of the paint used are not appropriate.

  From the above situation, the paint that covers the outer surface of the can lid has excellent paintability that can be applied to the reverse coating method, which is increasing in speed, and high coating that prevents troubles such as cut edge rough and wax accumulation during the lid making process. Membrane performance is required.

  On the other hand, from the viewpoints of resource saving, energy saving, environmental pollution, etc., can coatings are desired to be shifted to water systems, and lid coatings are no exception. Therefore, as the water-based paint for the lid, those composed of an acrylic-modified epoxy resin, a lubricant such as wax, and other additives have been widely studied.

  Such a water-based paint is usually obtained by dispersing each of the components such as resin and wax in advance in water or a hydrophilic solvent by individual methods, and then blending them.

  Therefore, Patent Document 1 discloses a wax dispersed in water with a resin having a specific structure, and an aqueous coating agent containing the wax. Patent Document 2 discloses an aqueous dispersion composition containing a wax emulsified and dispersed with a specific resin, a wax dispersed in a hydrophilic solvent, and a modified epoxy resin. Patent Document 3 discloses a water-based paint composition for can lid outer surfaces containing a wax having a specific melting point and particle size.

Japanese Patent Laid-Open No. 11-279489 Japanese Patent Laid-Open No. 11-343455 JP 2011-153247 A

  However, since the conventional water-based paint is an aqueous dispersion, its viscosity has a characteristic non-Newtonian fluidity. For this reason, coating film defects that did not occur when the coating was performed at a low speed tended to occur at a high speed. In addition, for example, when a reverse coating method is used for painting, a coating film defect (appearance defect of the coating film) is likely to occur due to its viscosity, and further, due to the coating defect, workability, metal adhesion, The film performance such as slipperiness and abrasion resistance may be deteriorated. In addition, there is a problem that cut edge rough and wax accumulation occur in the lid making process, making continuous production difficult.

  The present invention suppresses coating defects during high-speed coating, has excellent coating performance such as workability, metal adhesion, retort resistance, slipperiness, and wear resistance, and further, cut edge rough and wax in the lid making process. An object of the present invention is to provide a water-based paint for metal packaging materials that is unlikely to accumulate.

The present invention includes an aqueous dispersion of an acrylic-modified epoxy resin (A) and an aqueous wax dispersion (B) having an average particle diameter of 0.01 to 15 μm and a shear rate of 10,000 s ⁻¹ at 25 ° C. in a viscosity eta _H is 20~100mPa · s, and a viscosity eta _L at a shear rate of 0.1s ^-1, the ratio η _L / η _H and viscosity eta _H at a shear rate of 10000s ^-1 is 1-8 It is a water-based paint for metal packaging materials, characterized in that the average particle size of the aqueous wax dispersion (B) is 0.01 to 15 μm, and the water-based paint has a predetermined viscosity.

  According to the present invention having the above-described configuration, the high-speed coating is achieved by controlling the viscosity of the high-shear rate of the water-based paint within a predetermined range and further controlling the ratio of the low-shear rate viscosity to the high-shear rate viscosity within the predetermined range. At the same time, coating film defects are less likely to occur, and at the same time, it is possible to suppress wax accumulation and cut edge roughness during the lid making process.

  With the present invention, coating defects do not occur even during high-speed coating, and the coating performance such as workability, metal adhesion, retort resistance, slipperiness, and wear resistance is excellent. It is possible to provide a water-based paint for metal packaging materials that does not cause rough or wax accumulation.

  The aqueous coating material for metal packaging material of the present invention comprises an aqueous dispersion of an acrylic-modified epoxy resin (A) and an aqueous wax dispersion (B) having an average particle diameter of 0.01 to 15 μm, 25 The high shear rate viscosity at 0 ° C. is in a specific range, and the ratio between the low shear rate and the high shear rate viscosity is in a specific range. Therefore, the water-based paint for metal packaging materials is excellent in paintability when applied by a high-speed coating apparatus, for example, a reverse coat method or a die coat method, and the cured coating film has a smooth and uniform coating with little occurrence of coating defects. A membrane surface is obtained. Furthermore, it is possible to suppress the occurrence of cut edge rough and wax accumulation in the lid making process.

It is important that the viscosity characteristics of the water-based paint for metal packaging materials of the present invention (hereinafter also simply referred to as water-based paint) be within a specific range. Specifically, the viscosity η _H is preferably 20 to 100 mPa · s under the conditions of 25 ° C. and high shear rate of 10,000 s ⁻¹ . Water-based paints in this range exhibit excellent paintability because, for example, in reverse-coat paint, the paint pick-up property or paint transfer property between rolls is good. When the viscosity η _{H at} a shear rate of 10000 s ^-1 is less than 20 mPa · s, a cured coating that is formed due to insufficient paint pick-up or insufficient paint transfer between rolls in reverse coating. The coating amount of the film is reduced, and the workability and wear resistance of the coating film are reduced. In addition, the paint transfer between the rolls may be non-uniform, resulting in uneven coating defects. If the viscosity η _H is greater than 100 mPa · s, the amount of paint transfer between rolls becomes excessive, the coating amount of the cured coating film becomes excessive, or volatile substances such as an aqueous medium are foamed when the coating film is formed. It stays in the coating film and causes cracking.

Further, the aqueous coating of the present invention is a viscosity eta _L of the low shear rate conditions shear rate 0.1s ^-1, the viscosity ratio η _L / η _H and viscosity eta _H at a shear rate 10000s ^-1 previously described 1-8 It is preferable that A paint having a viscosity ratio within this range exhibits excellent paintability in reverse coating, and particularly, the surface of the cured coating film tends to be smooth and uniform. When η _L / η _H exceeds 8, the leveling property immediately after coating is remarkably deteriorated, and a so-called rib pattern generated when the paint is transferred from one roll to the other roll may remain in the cured coating film. . In addition, when η _L / η _H is less than 1, that is, fluidity generally called dilatancy, the viscosity at the time of painting becomes higher than the viscosity when the paint is left standing, so that the paint on the coating machine Flow stability is significantly reduced. Therefore, it may be difficult to adjust the coating amount or a smooth painted surface may not be obtained.

Various methods can be used to adjust η _L / η _H of the water-based paint of the present invention. Examples include control of the resin structure of the acrylic-modified epoxy resin (A), addition of various rheology control agents, The composition adjustment of the solvent contained in the paint can be shown. In order to increase η _L / η _H , for example, referring to the resin structure of the acrylic-modified epoxy resin (A), (1) the molecular weight of the acrylic resin portion is increased. (2) Increase the ratio of the acrylic resin portion. (3) An epoxy resin having a low epoxy equivalent is used. (4) There are methods such as increasing the degree of reaction in an esterification reaction described later. (5) Reducing the dispersed particle size of the aqueous dispersion of the acrylic-modified epoxy resin (A) is also effective for increasing η _L / η _H. On the other hand, in order to adjust η _L / η _H to be low, it is effective to perform an operation opposite to the above.
In rheology control agents, the use of so-called thixotropic agents is effective in increasing η _L / η _H , and examples thereof include celluloses, polyurethanes, polyacrylic acids, and polyamides.
Furthermore, the solvent composition in the aqueous paint, generally η _L / η _H is reduced By using many highly hydrophilic solvent, a relatively if the hydrophobic solvent composition η _L / η _H is higher tendency .

In the present invention, the viscosity at a specific shear rate was measured with a rheometer “Physica MCR301” manufactured by Anton Paar under a condition of 25 ° C. using a cone rotor having a diameter of 50 mm and a cone angle of 1 °. η _L is a viscosity measured after holding for 60 seconds at a shear rate of 0.1 s ⁻¹ , and η _H is a viscosity measured after holding for 10 seconds at a shear rate of 10000 s ⁻¹ .

  Next, the acrylic-modified epoxy resin (A), aqueous wax dispersion (B), ethylenically unsaturated monomer (C) containing a carboxyl group-containing monomer, and epoxy resin (D) used in the present invention will be described in detail. In the following description, the ethylenically unsaturated monomer (C) containing a carboxyl group-containing monomer may be simply abbreviated as ethylenically unsaturated monomer (C).

  The acrylic-modified epoxy resin (A) used in the present invention is preferably a composite resin obtained by using an ethylenically unsaturated monomer (C) and an epoxy resin (D).

The ethylenically unsaturated monomer (C) used in the present invention is preferably a carboxyl group-containing monomer and other ethylenically unsaturated monomers.
As the carboxyl group-containing monomer, (meth) acrylic acid ["acrylic acid" and "methacrylic acid" are collectively referred to as "(meth) acrylic acid". The same applies hereinafter. ], Maleic acid, itaconic acid, fumaric acid and the like.
Other ethylenically unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, alkyl (meth) acrylates such as t-butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate,
Hydroxyl groups such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, and hydroxyhexyl (meth) acrylate An ethylenically unsaturated monomer having
Aromatic monomers such as styrene and methylstyrene,
N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxyalkyl (meth) acrylamide such as N-hydroxybutyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (Meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N- (n-, iso) butoxyethyl (meta) ) N-alkoxyalkyl (meth) acrylamide such as acrylamide, and amide monomers such as (meth) acrylamide.

The ethylenically unsaturated monomer (C) has a carboxyl group concentration of 2 in consideration of the solution stability of the acrylic-modified epoxy resin (A), the fluidity of the paint, the workability when forming the coating film, and the metal adhesion. It is preferable to mix | blend so that it may become 0.7-7.1 mmol / g. When the carboxyl group concentration is less than 2.7 mmol / g, the water dispersibility may be lowered, and the storage stability as an aqueous paint may be impaired. In addition, the viscosity at a high shear rate such as a shear rate of 10000 s ^-1 may decrease, and a sufficient coating amount may not be ensured during coating, or coating defects such as unevenness may occur. On the other hand, when the carboxyl group concentration is higher than 7.1 mmol / g, it may be difficult to obtain processability, metal adhesion, and retort resistance when a coating film is formed. The carboxyl group concentration in the present invention is a theoretical value determined from the amount of the carboxyl group-containing monomer contained in the blended composition of the ethylenically unsaturated monomer (C), and represents the number of moles of carboxyl groups present per unit weight. It is what you point to.

  The ethylenically unsaturated monomer (C) is preferably used so that the weight ratio with the later-described epoxy resin (D) is (C) / (D) = 10/90 to 50/50. If the weight ratio of the ethylenically unsaturated monomer (C) is less than 10, the solution stability may be lowered, or the high shear rate viscosity may be lowered, resulting in poor paintability of the aqueous paint. Moreover, when the weight ratio of the ethylenically unsaturated monomer (C) is larger than 50, the workability, metal adhesion, and retort resistance when a coating film is formed tend to be inferior. In addition, since the low shear rate viscosity increases and the ratio of the low shear rate viscosity to the high shear rate viscosity increases, coating defects such as rolls may occur, and a good coating surface may not be obtained.

  The epoxy resin (D) used in the present invention is preferably an epoxy resin such as bisphenol type, novolac type, naphthalene type, or biphenyl type. Among these, bisphenol A type epoxy resin is more preferable in consideration of workability, retort resistance, and metal adhesion when formed into a coating film.

  In the present invention, the epoxy resin (D) preferably has a weight average molecular weight of 2500 to 70000. When the weight average molecular weight is less than 2500, the remaining amount of unreacted materials such as bisphenol A increases, and the workability and retort resistance may deteriorate. On the other hand, when the weight average molecular weight exceeds 70000, metal adhesion may be deteriorated.

  In the present invention, examples of commercially available epoxy resin (D) include JER1007, JER1009, and JER1010 manufactured by Mitsubishi Chemical Corporation.

As described above, the acrylic-modified epoxy resin (A) is preferably a composite resin obtained using the ethylenically unsaturated monomer (C) and the epoxy resin (D). (A) Graft polymerization method, (b) esterification method, (c) direct polymerization method and the like. That is,
(A) Graft polymerization method: polymerization of ethylenically unsaturated monomer (C) having a carboxyl group-containing monomer such as (meth) acrylic acid as an essential component using a radical polymerization initiator in the presence of epoxy resin (D). This is a method for obtaining an acrylic-modified epoxy resin (A) in which an acrylic copolymer is grafted onto an epoxy resin.
(A) Esterification method: An ethylenically unsaturated monomer (C) having a carboxyl group-containing monomer such as (meth) acrylic acid as an essential component is polymerized to obtain an acrylic polymer having a carboxyl group. Part and an epoxy group in epoxy resin (D) are esterified in the presence of a basic compound to obtain an acrylic-modified epoxy resin (A).
(C) Direct polymerization method: A part of the epoxy group in the epoxy resin (D) is reacted with a carboxyl group of a carboxyl group-containing monomer such as (meth) acrylic acid, and this compound and the carboxyl group-containing monomer are used as essential components. This is a method for obtaining an acrylic-modified epoxy resin (A) by copolymerizing an ethylenically unsaturated monomer (C).

  The acrylic-modified epoxy resin (A) can also be obtained by combining the above methods. For example, after carrying out graft polymerization by polymerizing the ethylenically unsaturated monomer (C) in the presence of the epoxy resin (D), an esterification reaction may be carried out by adding a basic compound, and the epoxy resin (D) and ( Examples thereof include a method in which an ethylenically unsaturated monomer (C) is copolymerized in the presence of a reaction product with (meth) acrylic acid or the like to perform direct polymerization and then esterify.

  In the above method, as the radical polymerization initiator used for polymerization, for example, an organic peroxide, a persulfate, an azobis compound, and a redox system in which these are combined with a reducing agent are preferably used. In the present invention, a peroxide-based initiator is preferable, and benzoyl peroxide is particularly preferable.

The radical polymerization initiator is preferably used in an amount of 1 to 10 parts by weight, more preferably 1 to 6 parts by weight, based on 100 parts by weight of the total amount of the ethylenically unsaturated monomer (C).
The reaction conditions such as temperature and time during the polymerization are not special, and known conditions can be used. It is important to obtain the acrylic-modified epoxy resin (A) by appropriately adjusting the reaction conditions so that the viscosity characteristics when the water-based paint is obtained are optimal.

In the above method, as the basic compound used in the esterification reaction, alcohol amines such as dimethylethanolamine (dimethylaminoethanol), ethanolamine, diethanolamine, aminomethylpropanol,
Alkylamines such as trimethylamine, triethylamine, butylamine,
Examples include volatile amines such as morpholine and ammonia.
The basic compound is preferably used in the reaction in a proportion of 1 to 80 mol%, more preferably 5 to 60 mol%, based on 100 mol% of the carboxyl group-containing monomer. The reaction conditions such as temperature and time during the esterification reaction are not special, and can be carried out using known conditions, but the reaction is appropriately performed so as to optimize the fluidity of the resulting aqueous paint. It is important to obtain the acrylic-modified epoxy resin (A) by adjusting the conditions.

  In order to make the obtained acrylic modified epoxy resin (A) into an aqueous dispersion, it can be obtained in the same manner as a conventional method. Specifically, this is a method of imparting hydrophilicity by neutralizing a carboxyl group present in the acrylic-modified epoxy resin (A) with a basic compound or the like. More specifically, after adding a basic compound to the acrylic-modified epoxy resin (A), an aqueous medium such as water is added to form an aqueous dispersion, or the basic compound is added to the acrylic-modified epoxy resin (A). Examples thereof include a method of adding an aqueous medium such as water to make an aqueous dispersion.

The aqueous wax dispersion (B) used in the present invention is a dispersion of wax in an aqueous medium. The average particle diameter of the dispersed particles is preferably 0.01 to 15 μm. When the average particle diameter of the aqueous wax dispersion (B) is within the above range, it is easy to achieve both coating performance such as slipperiness and wear resistance, and suppression of wax accumulation and cut edge roughness during lid making. .
In the present invention, the average particle size of the dispersed particles of the aqueous wax dispersion (B) is measured using “Nanotrack UPA-EX150” manufactured by Nikkiso Co., Ltd., and “Acucizer780” manufactured by PARTICLE SIZING SYSTEMS. .

  Examples of the aqueous medium of the aqueous wax dispersion (B) of the present invention include alcohols, glycols, glycol ethers, various hydrophilic solvents such as acetates and water, and these may be used alone. You may mix and use each.

  The aqueous wax dispersion (B) of the present invention is roughly classified into two types, an emulsified type and a non-emulsified type, depending on its properties. As this feature, the emulsion type has a small average particle diameter of dispersed particles of about 0.01 to 1 μm, and the emulsion type has a large average particle diameter of about 0.5 to 15 μm. The emulsification type is characterized by being excellent in dispersion stability because the average particle size of the dispersed particles is small, and having a relatively uniform coating on the surface of the coating film resin when forming the coating film. The non-emulsifying type has a feature that it can impart excellent abrasion resistance to the coating film because of its large average particle size. In the present invention, both can be used alone or in combination according to the application.

  Examples of the wax of the aqueous wax dispersion (B) of the present invention include natural wax and synthetic wax.

  Examples of natural waxes include animal and plant waxes such as beeswax, lanolin wax, whale wax, candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil and the like. In addition, examples include minerals such as montan wax, ozogelite, ceresin, paraffin wax, microcrystalline wax, petrolatum, petroleum wax, and the like. Of these, carnauba wax, candelilla wax, rice wax, lanolin wax, and microcrystalline wax are preferred in consideration of slipperiness and abrasion resistance when a coating film is formed.

Synthetic waxes include synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax,
Modified waxes such as montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives,
Hydrogenated waxes such as hardened castor oil, hardened castor oil derivatives,
Examples include polytetrafluoroethylene (PTFE) wax. In consideration of the slipperiness and wear resistance of the cured coating film, polyethylene wax and microcrystalline wax derivatives are preferred.

As a commercially available product of the aqueous wax dispersion (B) in the present invention,
Hydrocer 100 (polyethylene wax), Hydrocer 257 (polyethylene wax), Hydrocer 600 (microcrystalline / polyethylene mixed wax), Hydrocer 901 (polyethylene / paraffin mixed wax), Hydrocerf 9174 (PTFE), Fluor 60E, Fluor 60E Emulsified carnauba wax), Hydrocer EE95 (emulsified polyethylene wax) Hydrocer EM08 (emulsified microcrystalline wax), Hydrocer EP91 (emulsified paraffin wax),
BYK's CERACOL39 (polyethylene wax), CERACOL79 (carnauba wax), CERACOL601 (carnauba wax), AQUACER498 (emulsified paraffin wax), AQUACER507 (emulsified polyethylene wax), AQUACER1547 (emulsified polyethylene wax),
SL506 (carnauba wax), SL508 (carnauba wax), SL19 (polyethylene wax), SL145E (emulsified paraffin wax), SL535E (emulsified carnauba wax), SL330E (emulsified polyethylene wax), manufactured by Elementis Japan Co., Ltd.
HYTEC E-5403P (emulsified polyethylene wax), HYTEC E-8237 (emulsified polyethylene wax), E-1000 (emulsified polyethylene wax), HYTEC E-4A) manufactured by Toho Chemical Industries, Ltd.
Examples thereof include Microspersion 215-50 (polyethylene wax), Microspersion 250 (polyethylene wax), Microspersion 930 (polyethylene wax), Microspersion 190-50 (polyethylene / PTFE mixed wax), Microspersion 411 (polyethylene / PTFE mixed wax) manufactured by MICRO POWDERS.

  In the aqueous wax dispersion (B) of the present invention, a resin having an acid value of 100 to 500 mgKOH / g and a number average molecular weight of 2000 to 50000 is used as a polymer surfactant, and the wax is emulsified and dispersed in an aqueous medium. It is preferable to contain the wax aqueous dispersion (b1).

  The resin can be used as a polymer surfactant by neutralizing a carboxyl group or the like in the resin with a basic compound described later. When the acid value of the resin is less than 100 mg KOH / g, the emulsification function after neutralization is small, and it becomes difficult to stably disperse the wax, and a wax aggregate may be formed in the aqueous wax dispersion (b1). is there. On the other hand, when the acid value exceeds 500 mgKOH / g, the water resistance of the coating film obtained from the aqueous dispersion composition of the present invention containing the aqueous wax dispersion (b1) may be lowered. Moreover, it becomes easier to emulsify or disperse the wax when the resin has a number average molecular weight of 2000 to 50000. The number average molecular weight of the resin is more preferably 2000 to 20000. The resin is preferably at least one of an acrylic resin having a carboxyl group or a polyester resin having a carboxyl group.

  The aqueous wax dispersion (b1) is preferably 1 to 50 parts by weight of resin and 50 to 99 parts by weight of wax in a total of 100 parts by weight of resin and wax. When the resin and the wax are used in the above amounts, it is easy to achieve both dispersion stability and coating film performance. In addition, it is more preferable that resin is 2-20 weight part.

  Among the resins used in the aqueous wax dispersion (b1), the acrylic resin having a carboxyl group is obtained by polymerizing the ethylenically unsaturated monomer (C) described above.

Among the resins used in the aqueous wax dispersion (b1), a polyester resin having a carboxyl group can be obtained by a reaction between a polyhydric alcohol component and a polybasic acid component according to a conventional method.
Examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, and other dihydric alcohols, glycerin, and trimethylol. Examples include alcohol components such as ethane, trimethylolpropane, trishydroxymethylaminoethane, pentaerythritol, dipentaerythritol, and diglycerin.
The polybasic acid components include (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, (anhydrous) succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydro (anhydrous) phthalic acid, hexahydro (anhydrous) phthalic acid, (anhydrous) Polyhydric carboxylic acids such as highmic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, (anhydrous) trimellitic acid, methylene dicyclohexylene carboxylic acid (anhydride), (anhydrous) pyromellitic acid, or anhydrides thereof, and Examples thereof include monobasic acids such as benzoic acid and t-butylbenzoic acid, which are used in combination as necessary.
In the reaction, these may be used alone or in combination of two or more.

  In addition, the polyester resin having a carboxyl group includes castor oil, dehydrated castor oil, tung oil, safflower oil, soybean oil, flaxseed oil, tall oil, coconut oil, and the like in addition to the alcohol component and acid component. An alkyd resin obtained by reacting three components by adding an oil component which is one or a mixture of two or more fatty acids to the acid component and the alcohol component. Moreover, the graft modified polyester resin modified | denatured by grafting an acrylic resin to the polyester resin which has an unsaturated bond is also mentioned.

  The aqueous wax dispersion (b1) is obtained by dispersing a wax in an aqueous medium by using a neutralized resin having a specific acid value and a number average molecular weight as a polymer surfactant. . For neutralization, basic compounds are used, and those having volatility are preferred. In addition to ammonia, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine (dimethylaminoethanol), cyclohexylamine, etc. Can be mentioned.

  There are various means for obtaining the aqueous wax dispersion (b1). For example, a resin, a wax, a basic compound, a method of stirring an aqueous medium at a temperature not lower than the melting point of the wax, and a molten mixture of the resin and the wax And a method of stirring and mixing this with a basic compound and an aqueous medium, a resin and wax, a method of mixing an aqueous medium with a molten compound, and stirring and mixing this with a basic compound, and a resin, an aqueous medium and a base Examples thereof include a method of stirring and mixing a resin aqueous solution or aqueous dispersion obtained by mixing a functional compound and a molten wax.

  Various aqueous wax dispersions with different dispersed particle sizes by varying the amount of resin, wax, volatile base, and aqueous medium, neutralization ratio, mixing conditions (mixing speed, stirring conditions, temperature, etc.), etc. The body (b1) can be obtained.

  Moreover, the organic solvent which exists in the dispersion | distribution process in the aqueous medium of the said wax can be removed under reduced pressure as needed. At this time, water and the organic solvent may be removed as an azeotropic mixture. In such a case, it is more preferable to use a solvent that can be easily removed from the organic solvent, that is, an organic solvent having a relatively low boiling point.

  The average particle size of the dispersed particles of the aqueous wax dispersion (b1) varies depending on the temperature and stirring speed when dispersed in the aqueous medium, the acid value of the resin used, the ratio with the wax, and the like. In order to obtain dispersion stability and good slipperiness and abrasion resistance when a coating film is formed, the average particle diameter is preferably 0.1 to 1 μm, more preferably 0.1 to 0.5 μm. 0.2 to 0.4 μm is most preferable.

  Furthermore, the aqueous wax dispersion (B) of the present invention preferably contains an aqueous wax dispersion (b2) in which a wax is dispersed in an aqueous medium in the absence of a surfactant. For example, the aqueous wax dispersion (b2) is obtained by gradually adding and dispersing a wax and a hydrophilic solvent heated to a melting point of the wax or higher in an aqueous medium that is stirred at a high speed, The mixture is heated to a temperature higher than the melting point of the wax, and the mixture is gradually added and dispersed in the aqueous medium with high-speed stirring, or the aqueous medium containing the wax and the hydrophilic solvent is increased to the temperature higher than the melting point of the wax. After heating to a mixed solution, it can be obtained by gradually cooling and dispersing to below the melting point of the wax under high-speed stirring.

  In producing the aqueous wax dispersion (b2), the hydrophilic solvent used in the dispersion process is preferably one that is easily mixed with water, and examples thereof include alcohols, glycols, glycol ethers, and acetates. These hydrophilic solvents are preferably removed after the wax is dispersed, if necessary, under reduced pressure or by azeotropy with water.

  Since the aqueous wax dispersion (b2) does not contain a surfactant, when the aqueous paint containing the aqueous wax dispersion (b2) is used to form a paint film, the water resistance of the paint film is excellent. . Incidentally, the surfactant referred to here is a fatty acid such as stearic acid or oleic acid, a polyethylene glycol fatty acid ester such as ethylene glycol monolaurate or diethylene glycol monostearate, or a polyoxyethylene alkyl ether such as polyoxyethylene lauryl ether. Mainly having a relatively low molecular weight such as polyoxyethylene alkylphenol ethers such as polyoxyethylene nonylphenol, etc. In the present invention, “acid value 100 to 500 mgKOH / g and a resin having a number average molecular weight of 2,000 to 50,000 are also included in the “surfactant” herein.

  Examples of the wax used in the aqueous wax dispersion (b2) are the same as those described above. However, when a synthetic wax is used in the aqueous wax dispersion (b2), it is preferable to use it in combination with a natural wax rather than using it alone. The natural wax assists in stabilizing the dispersion of the synthetic wax, and has an effect that aggregates are less likely to be generated in the aqueous medium and stabilization is facilitated.

  The aqueous wax dispersion (b2) has an average particle diameter of dispersed particles in order to ensure good dispersion stability and high hardness and excellent wear resistance of a coating film formed from an aqueous coating material containing the wax dispersion. Is preferably 1 to 15 μm, and more preferably 1 to 10 μm.

  It is preferable to use 0.1 to 10 parts by weight of the wax with respect to 100 parts by weight of the acrylic-modified epoxy resin (A). If the wax is less than 0.1 part by weight, the slipping property and wear resistance of the resulting cured coating film tend to be reduced. On the other hand, if the amount of the wax exceeds 10 parts by weight, the amount of the wax present in the coating film increases, which may cause wax deposition.

  The aqueous paint of the present invention preferably has a surface tension of 25 to 33 mN / m. When the surface tension is less than 25 mN / m, coating defects such as rolls may occur. On the other hand, when it exceeds 33 mN / m, the wettability of the water-based paint with respect to the metal plate may be deteriorated, or a repellency defect may occur in the formed cured coating film. In the present invention, the surface tension is measured by the Wilhelmy method using a fully automatic surface tension meter “CBVP-Z type” manufactured by Kyowa Interface Science Co., Ltd. and using a platinum plate as a probe.

  The aqueous paint of the present invention preferably contains 5 to 30% of an organic solvent for the purpose of improving paintability. When the organic solvent is used to obtain the acrylic-modified epoxy resin (A), the organic solvent used in the reaction step may be contained in the water-based paint of the present invention as it is, or may be added separately as necessary.

Although it does not specifically limit as an organic solvent, The solvent with comparatively high hydrophilicity as shown below is preferable. Specifically, for example,
Methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, sec-amyl alcohol, n-octanol, 2- Alcohols such as ethyl-1-hexanol and tridecanol,
Glycols such as ethylene glycol, diethylene glycol, 1,3-butylene glycol,
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methylpropylene glycol, methylpropylene diglycol, propylpropylene glycol, propylpropylene diglycol, butyl Glycol ethers such as propylene glycol and dipropylene glycol monomethyl ether,
Examples thereof include acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methobutyl acetate, ethylene glycol monobutyl ether acetate, and 3-methyl-3-methoxybutyl acetate.
In the present invention, from the viewpoints of storage stability of the water-based paint, surface tension control effect, and solvent volatilization rate at the time of coating, the organic solvent (E) used is an alkylene glycol monoalkyl having 1 to 6 carbon atoms in the alkyl group. An alkyl ether or an alkyl alcohol having 1 to 10 carbon atoms in the alkyl group is preferable, and it is more preferable to use both in combination.

  The aqueous coating material of the present invention may further contain one or more curing agents such as phenol resins and amino resins for the purpose of improving the curability and metal adhesion of the coating film as necessary. .

  A phenol resin or an amino resin can react with a carboxyl group in the acrylic-modified epoxy resin (A) in addition to a self-crosslinking reaction. Further, when the acrylic-modified epoxy resin (A) has a hydroxyl group, the phenol resin or amino resin can react with those hydroxyl groups. Furthermore, when the ethylenically unsaturated monomer (C) contains an amide monomer and the acrylic-modified epoxy resin (A) has a crosslinkable functional group derived from this amide monomer, it can also react with these crosslinkable functional groups. .

  In the present invention, as the phenol resin, trifunctional phenol compounds such as phenol, m-cresol and 3,5-xylenol, bifunctional phenol compounds such as o-cresol, p-cresol and p-tert-butylphenol and formaldehyde are used. Examples include those reacted in the presence of an alkali catalyst. In this case, a phenol compound is used individually or in combination of 2 or more types.

  In the present invention, examples of amino resins include those obtained by addition reaction of formaldehyde with amino compounds such as urea, melamine, and benzoguanamine. In this case, an amino compound is used individually or in combination of 2 or more types.

  As the phenol resin and amino resin, those obtained by etherifying some or all of the methylol groups formed by addition of formaldehyde with alcohols having 1 to 12 carbon atoms are also preferably used.

  When using a phenol resin or an amino resin, it is preferable to add 0.5-20 weight part with respect to 100 weight part of acrylic modified epoxy resins (A), and it is more preferable to add 1-10 weight part.

  The water-based coating material for metal packaging material of the present invention can be added with a solvent, a surfactant and an antifoaming agent for improving the paintability as required.

  The water-based coating material for metal packaging material of the present invention can be applied to various substrates, and a metal packaging material having a coating layer formed from the water-based coating material on a metal plate can be obtained. As a base material, for example, various kinds of untreated or surface-treated metals such as an aluminum plate, a steel plate, a tin plate, a metal coated with a primer on these metals, or a polyester film (PET) laminated on these metals. Examples include PET-coated metals. As a use of the metal packaging material of the present invention, a metal can that contains beverages, foods and the like is preferable. The types include DI cans (cans manufactured by the drawing & ironing method), DR cans (cans manufactured by the drawing & redrawing method), various three-piece cans, and film laminate cans.

  Further, the shape of the substrate may be a plate shape or a bottomed cylindrical shape. After applying the aqueous coating material for metal packaging materials of the present invention to these substrates and curing, further deformation may be applied. A packaging material can be obtained through various processing steps.

  Various known methods such as roll coater coating, spray coating, dip coating, electrodeposition coating, and the like can be applied as a method for coating the base material with the water-based coating material for metal packaging material of the present invention. As drying conditions for the coated paint, it is usually preferable that the surface temperature of the substrate is 120 to 300 ° C. for 10 seconds to 30 minutes.

Coating amount after drying may be appropriately selected depending on the application, but usually about 5 to 200 mg / dm ² is preferred. In particular, when used as the outer surface portion of the lid, 10 to 100 mg / dm ² is preferable.

  The metal packaging material of the present invention preferably has a surface free energy of 25 to 45 mN / m of the coating layer. If the surface free energy of the coating layer is less than 25 mN / m, the amount of wax present in the coating layer becomes excessive, which may cause wax deposition. Also, if the surface free energy of the coating layer is greater than 45 mN / m, the amount of wax present in the coating layer tends to decrease, and the slipperiness of the coating layer decreases and the wear resistance decreases. There are concerns. The surface free energy of the coating layer in the present invention is calculated by measuring the contact angle between the coating and the liquid sample. For the measurement, an automatic contact angle meter “CA-V type” manufactured by Kyowa Interface Science Co., Ltd. was used, and water, methylene iodide, and n-hexadecane were used as liquid samples, and the respective contact angles were measured.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, this does not limit the scope of rights of the present invention. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

[Production Example 1]
<Synthesis of acrylic modified epoxy resin (A-1)>
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube, 210.0 parts of JER1009 (Mitsubishi Chemical Corporation bisphenol A type epoxy resin), ethylene glycol monobutyl ether 80 Part and 75 parts of n-butanol were charged and heated to 120 ° C. to dissolve. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 28.0 parts of methacrylic acid, 35.0 parts of styrene, 7.0 parts of ethyl acrylate, and 2.8 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.4 parts of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C. Subsequently, after 10.2 parts of dimethylaminoethanol was added and stirred for 10 minutes, 485 parts of water was added dropwise over 1 hour, and an aqueous dispersion of acrylic modified epoxy resin (A-1) having a nonvolatile content of 30% was obtained. Obtained.

[Production Example 2]
<Synthesis of acrylic modified epoxy resin (A-2)>
In a reaction vessel similar to Production Example 1, 210.0 parts of JER1009, 80 parts of ethylene glycol monobutyl ether, and 75 parts of n-butanol were charged and heated to 120 ° C. for dissolution. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 28.0 parts of methacrylic acid, 35.0 parts of styrene, 7.0 parts of ethyl acrylate, and 2.8 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.4 parts of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C.
Subsequently, 5.8 parts of dimethylaminoethanol and 5.8 parts of water were mixed and added, and an esterification reaction was performed at 90 ° C. for 1 hour.
After completion of the reaction, 4.4 parts of dimethylaminoethanol was added and stirred for 10 minutes, and then 479 parts of water was added dropwise over 1 hour to prepare an aqueous dispersion of an acrylic-modified epoxy resin (A-2) having a nonvolatile content of 30%. Obtained.

[Production Example 3]
<Synthesis of acrylic modified epoxy resin (A-3)>
The acrylic modified epoxy resin (A-3) having a nonvolatile content of 30% was prepared in the same manner as in Production Example 1 except that 17.5 parts of methacrylic acid, 46.9 parts of styrene, and 5.6 parts of ethyl acrylate were used. An aqueous dispersion was obtained.

[Production Example 4]
<Synthesis of acrylic modified epoxy resin (A-4)>
The acrylic modified epoxy resin (A-4) having a nonvolatile content of 30% was prepared in the same manner as in Production Example 1 except that 42.0 parts of methacrylic acid, 18.9 parts of styrene, and 9.1 parts of ethyl acrylate were used. An aqueous dispersion was obtained.

[Production Example 5]
<Synthesis of acrylic modified epoxy resin (A-5)>
In a reaction vessel similar to Production Example 1, 238.0 parts of JER1009, 80 parts of ethylene glycol monobutyl ether, and 75 parts of n-butanol were charged and heated to 120 ° C. for dissolution. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 16.8 parts of methacrylic acid, 21.0 parts of styrene, 4.2 parts of ethyl acrylate, and 1.7 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.3 part of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C. Subsequently, after 10.2 parts of dimethylaminoethanol was added and stirred for 10 minutes, 486 parts of water was added dropwise over 1 hour, and an aqueous dispersion of acrylic modified epoxy resin (A-5) having a nonvolatile content of 30% was obtained. Obtained.

[Production Example 6]
<Synthesis of acrylic modified epoxy resin (A-6)>
In a reaction vessel similar to Production Example 1, 168.0 parts of JER1009, 80 parts of ethylene glycol monobutyl ether, and 75 parts of n-butanol were charged and heated to 120 ° C. to be dissolved. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 44.8 parts of methacrylic acid, 56.0 parts of styrene, 11.2 parts of ethyl acrylate, and 4.5 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.7 part of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C. Subsequently, after 10.2 parts of dimethylaminoethanol was added and stirred for 10 minutes, 482 parts of water was added dropwise over 1 hour, and an aqueous dispersion of acrylic modified epoxy resin (A-6) having a nonvolatile content of 30% was obtained. Obtained.

[Production Example 7]
<Synthesis of acrylic modified epoxy resin (A-7)>
In a reaction vessel similar to Production Example 1, 210.0 parts of JER1009, 80 parts of ethylene glycol monobutyl ether, and 75 parts of n-butanol were charged and heated to 120 ° C. for dissolution. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 28.0 parts of methacrylic acid, 35.0 parts of styrene, 7.0 parts of ethyl acrylate, and 4.2 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.6 parts of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C. Subsequently, after adding 8.7 parts of dimethylaminoethanol and stirring for 10 minutes, 484 parts of water was added dropwise over 1 hour, and an aqueous dispersion of acrylic modified epoxy resin (A-7) having a nonvolatile content of 30% was obtained. Obtained.

[Production Example 8]
<Synthesis of acrylic modified epoxy resin (A-8)>
In a reaction vessel similar to Production Example 1, 210.0 parts of JER1009, 80 parts of ethylene glycol monobutyl ether, and 75 parts of n-butanol were charged and heated to 120 ° C. for dissolution. While maintaining the temperature in the reaction vessel at 120 ° C., a mixture of 28.0 parts of methacrylic acid, 35.0 parts of styrene, 7.0 parts of ethyl acrylate, and 2.8 parts of benzoyl peroxide was added from the dropping tank for 1 hour. It was dripped continuously over. After 1 hour and 2 hours from the end of dropping, 0.4 parts of benzoyl peroxide was added, and the reaction was continued for 3 hours from the end of dropping, and then cooled to 90 ° C.
Subsequently, 10.2 parts of dimethylaminoethanol and 10.2 parts of water were mixed and added, and an esterification reaction was performed at 90 ° C. for 2 hours.
After completion of the reaction, 474 parts of water was added dropwise over 1 hour to obtain an aqueous dispersion of an acrylic-modified epoxy resin (A-8) having a nonvolatile content of 30%.

[Production Example 9]
<Synthesis of acrylic resin solution (f) for wax dispersion>
590 parts of n-butanol was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube, and the temperature was raised to 110 ° C. A mixture of 90 parts of methacrylic acid, 105 parts of styrene, 105 parts of ethyl acrylate, 100 parts of n-butanol and 5 parts of benzoyl peroxide was continuously added dropwise from a dropping tank over 3 hours. After 1 hour and 2 hours from the end of the dropwise addition, 0.5 parts of benzoyl peroxide was added, and the reaction was continued for 3 hours after the completion of the dropwise addition. Acrylic having a number average molecular weight of 17000, an acid value of 195 mgKOH / g, and a nonvolatile content of 30% A resin solution was obtained. This is designated as an acrylic resin solution (f) for wax dispersion.

[Production Example 10]
<Production of aqueous wax dispersion (B-1)>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dripping tank, and a nitrogen gas introduction tube, 100 parts of purified carnauba wax, acrylic resin solution (f) 16.2 for wax dispersion obtained in Production Example 4 The portion was charged and heated to 90 ° C. and dissolved by mixing. Next, 3.1 parts of dimethylaminoethanol was added and stirred, and then emulsified by gradually adding 880 parts of water while maintaining the temperature in the reaction vessel at 85 to 90 ° C. After completion of the addition, the mixture was cooled to 40 ° C. over 1 hour to obtain a wax dispersion having a nonvolatile content of 11%, a wax content concentration of 10%, and an average particle size of 0.3 μm. This is designated as wax aqueous dispersion (B-1).

[Production Example 11]
<Production of aqueous wax dispersion (B-2)>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dripping tank, and a nitrogen gas introduction tube, 80 parts of “S394-N5” (polyethylene wax manufactured by Shamrock Technologies), 20 parts of purified carnauba wax, ethylene glycol mono After adding 900 parts of butyl ether and heating to 120 ° C. to dissolve the mixture, 2.1 parts of dimethylaminoethanol was added and stirred. Next, under the absence of a surfactant, the mixed solution in the reaction vessel is gradually cooled to 60 ° C. over 1 hour under high-speed stirring to precipitate wax, and further cooled to 40 ° C. to become non-volatile. A wax dispersion having a content of 10% and an average particle size of 8 μm was obtained. This is designated as wax aqueous dispersion (B-2).

[Production Example 12]
<Production of aqueous wax dispersion (B-3)>
In a reaction vessel equipped with a stirrer and a thermometer, 20 parts of “S394-N5” and 80 parts of ethylene glycol monobutyl ether were charged and stirred to obtain a wax dispersion having a non-volatile content of 20% and an average particle diameter of 18 μm. This is designated as wax aqueous dispersion (B-3).

[Example 1]
100 parts of an aqueous dispersion of the acrylic-modified epoxy resin (A-1) obtained in Production Example 1 and “Hydrocer 257” (polyethylene wax aqueous dispersion manufactured by Shamrock Technologies, average particle diameter of 5 μm, non-volatile content of 50%) .60 parts, "SL506" (Carnauba wax aqueous dispersion manufactured by Elementis Japan Co., Ltd., average particle diameter 2 μm, nonvolatile content 18.5%) 1.62 parts, water 7 parts, nonvolatile content 28% The water-based paint for metal packaging materials was obtained. The obtained coating material has a viscosity η _H (hereinafter simply referred to as η _H ) at a shear rate of 10,000 s ⁻¹ of 47 mPa · s, a viscosity η _{L under} a low shear rate condition with a shear rate of 0.1 s ⁻¹ , The viscosity ratio η _L / η _H (hereinafter simply referred to as η _L / η _H ) with the viscosity η _H at a shear rate of 10,000 s ⁻¹ was 3.2. The surface tension was 27.1 mN / m.

[Example 2]
While stirring 100 parts of the water-based coating material for metal packaging material obtained in Example 1, 0.1 part of dimethylaminoethanol as a viscosity modifier was added to obtain a water-based coating material for metal packaging material having a nonvolatile content of 28%. Η _H of the obtained coating material was 68 mPa · s, and η _L / η _H was 4.5. The surface tension was 26.9 mN / m.

[Example 3]
Under stirring of 100 parts of the aqueous coating material for metal packaging material obtained in Example 1, 0.3 part of dimethylaminoethanol was stirred and mixed to obtain an aqueous coating material for metal packaging material having a nonvolatile content of 28%. Η _H of the obtained paint was 98 mPa · s, and η _L / η _H was 5.2. The surface tension was 27.0 mN / m.

[Example 4]
Instead of the acrylic modified epoxy resin (A-1), an aqueous solution for metal packaging material having a non-volatile content of 28% was obtained in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of the acrylic modified epoxy resin (A-2) was used. A paint was obtained. Η _H of the obtained paint was 45 mPa · s, and η _L / η _H was 7.6. The surface tension was 26.7 mN / m.

[Example 5]
An aqueous coating material for metal packaging materials having a nonvolatile content of 28% was obtained in the same manner as in Example 1 except that 3 parts of the aqueous wax dispersion (B-1) was used instead of “SL506” and 6 parts of water was added. . Η _H of the obtained paint was 43 mPa · s, and η _L / η _H was 3.3. The surface tension was 26.8 mN / m.

[Example 6]
An aqueous coating material for metal packaging materials having a nonvolatile content of 28% was obtained in the same manner as in Example 1 except that 3 parts of the aqueous wax dispersion (B-2) was used instead of “Hydrocer 257” and 5 parts of water was added. . Η _H of the obtained paint was 51 mPa · s, and η _L / η _H was 3.2. The surface tension was 26.9 mN / m.

[Example 7]
Example 1 except that 3 parts of the aqueous wax dispersion (B-1) and 3 parts of the aqueous wax dispersion (B-2) were used instead of “SL506” and “Hydrocer 257” respectively, and 3 parts of water was added. In the same manner as above, an aqueous coating material for metal packaging material having a nonvolatile content of 28% was obtained. Η _H of the obtained paint was 49 mPa · s, and η _L / η _H was 3.5. The surface tension was 27.0 mN / m.

[Example 8]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-3) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 39 mPa · s, and η _L / η _H was 3.3. The surface tension was 27.3 mN / m.

[Example 9]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-4) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 59 mPa · s, and η _L / η _H was 3.8. The surface tension was 27.2 mN / m.

[Example 10]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-5) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 40 mPa · s, and η _L / η _H was 2.8. The surface tension was 27.4 mN / m.

[Example 11]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-6) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 52 mPa · s, and η _L / η _H was 5.8. The surface tension was 27.1 mN / m.

[Example 12]
Under stirring of 100 parts of the water-based coating for metal packaging material obtained in Example 1, 1.65 parts of “PR-C-10” (Sumitomo Bakelite Co., Ltd. phenol resin solution, nonvolatile content 50%), 1 part of water Was added to obtain a water-based paint for metal packaging materials having a nonvolatile content of 28%. Η _H of the obtained paint was 48 mPa · s, and η _L / η _H was 3.5. The surface tension was 27.0 mN / m.

[Comparative Example 1]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-7) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 18 mPa · s, and η _L / η _H was 2.5. The surface tension was 26.9 mN / m.

[Comparative Example 2]
For metal packaging materials having a non-volatile content of 28% in the same manner as in Example 1 except that 100 parts of an aqueous dispersion of acrylic modified epoxy resin (A-8) was used instead of acrylic modified epoxy resin (A-1). An aqueous paint was obtained. Η _H of the obtained paint was 46 mPa · s, and η _L / η _H was 8.6. The surface tension was 27.5 mN / m.

[Comparative Example 3]
Under stirring of 100 parts of the water-based coating material for metal packaging material obtained in Example 1, 0.6 part of dimethylaminoethanol was stirred and mixed to obtain a water-based coating material for metal packaging material having a nonvolatile content of 28%. Η _H of the obtained paint was 119 mPa · s, and η _L / η _H was 5.6. The surface tension was 27.4 mN / m.

[Comparative Example 4]
An aqueous coating material for metal packaging materials having a nonvolatile content of 28% was obtained in the same manner as in Example 1 except that 1.5 parts of the aqueous wax dispersion (B-3) was used instead of “Hydrocer 257” and 6 parts of water was added. Obtained. Η _H of the obtained paint was 49 mPa · s, and η _L / η _H was 3.5. The surface tension was 26.9 mN / m.

[Evaluation of physical properties]
The paintability of the water-based paints for metal packaging materials obtained in Examples 1 to 12 and Comparative Examples 1 to 4 was evaluated. In addition, each water-based paint was applied to prepare a test panel, and various physical properties of the coating film were evaluated in the following items. The test panel was prepared by coating each water-based paint on a 0.26 mm thick aluminum plate with a bar coater so that the dry coating weight was 45 mg / dm ^2, and then in an oven set at 250 ° C. for 1 minute. Created by baking.

<Paintability>
Using a reverse coater, the paintability of the water-based paints for metal packaging materials obtained in Examples 1 to 12 and Comparative Examples 1 to 4 was confirmed. The condition of the reverse coater is “peripheral speed ratio: backup roll / application roll / pickup roll = 1 / 1.1 to 1.7 / 0.3” so that the coating amount is 45 mg / dm ² at room temperature of 26 ° C. It was painted and its coating state was visually evaluated. The coating was performed using a sheet-like aluminum plate affixed on a backup roll as a base material. The evaluation criteria are as follows.
A: There is no coating defect. Good.
○: There is very little coating unevenness, roll eyes, or armpits. There is no practical problem.
Δ: Clearly any of coating unevenness, roll eyes, or armpits. I can not use it.
X: There are any significant coating unevenness, roll eyes, or armpits. I can not use it.

<Dynamic friction coefficient>
A weight of 1 kg with three steel balls attached to the coating surface of the test panel was placed so that the steel balls were in contact with the coating surface, and this weight was pulled at a speed of 150 cm / min. The dynamic friction coefficient of was measured. The smaller the dynamic friction coefficient, the better the slipperiness.

<Scratch measurement>
Using tribogear HEIDON-22H (manufactured by Shinto Kagaku Co., Ltd.), scratch measurement with a scratch needle of 100 microns, a scratch length of 50 mm, and a scratch speed of 300 mm / min. Went. The coating film was scratched, and the load when the scratch reached the aluminum substrate was measured.
(Double-circle): There is no generating of a crack. Good.
○: Load 400 g or more. There is no practical problem.
(Triangle | delta): Load 300g or more and less than 400g. I can not use it.
X: Load is less than 300 g. I can not use it.

<Abrasion resistance>
Using a tribogear HEIDON-22H (manufactured by Shinto Kagaku Co., Ltd.), a stainless steel ball having a contact diameter of 3 mm was reciprocated on the test panel under the conditions of a load of 1000 g, a reciprocating width of 2 mm, and a reciprocating speed of 300 mm / min. The coating film was scratched and the number of reciprocations until the scratch reached the aluminum substrate was measured.
A: The number of round trips is 1000 times or more. Good.
○: 500 times or more and less than 1000 times. There is no practical problem.
Δ: 200 times or more and less than 500 times. I can not use it.
X: Less than 200 times. I can not use it.

<Bending workability>
The test panel is cut into a size of 30 mm × 50 mm, the coating is on the outside, the hand is previously folded by hand so that the test site has a width of 30 mm, and a thickness of 0.26 mm is placed between the two test pieces. The aluminum plate was sandwiched between 5 sheets, and a 1 kg load was dropped from a height of 40 cm onto the bent portion and completely bent. Next, the bent tip of the test piece was immersed in a 1% strength saline solution, and 6.0 V × 6 seconds was passed between the metal part of the test piece not immersed in the saline solution and the saline solution. The current value was measured.
When the processability of the coating film is poor, the coating film in the bent portion is cracked, the underlying metal plate is exposed, and the conductivity is increased, so that a high current value can be obtained.
A: Less than 5.0 mA. Good.
○: 5.0 mA or more and less than 10 mA. No problem in practical use.
Δ: 10 mA or more and less than 20 mA. I can not use it.
X: 20 mA or more. I can not use it.

<Adhesion>
While the test panel was immersed in water, retort treatment was performed in a retort kettle at 130 ° C. for 1 hour. After the cut surface of the coated film was cross-cut with a cutter, a cellophane pressure-sensitive adhesive tape was attached, and the peeled state of the coated surface after being strongly peeled was evaluated.
A: No peeling at all. Good.
○: Less than 5% peeling. No problem in practical use.
(Triangle | delta): There exists peeling of 5-20%. I can not use it.
X: Peeling exceeding 20%. I can not use it.

<Water resistance>
While the test panel was immersed in water, a retort treatment was performed at 130 ° C. for 1 hour in a retort kettle, and the appearance of the coating film was visually evaluated.
A: Untreated coating film and no change. Good.
○: Slight whitening. There is no practical problem.
Δ: Slightly whitened. I can not use it.
X: Remarkably whitened. I can not use it.

<Wax depositability>
Using a lid-making press, 200 lids were processed for each test panel, and then the wax deposited on the press mold from the test panel was visually evaluated.
(Double-circle): There is no deposit. Good.
○: Slightly deposited. There is no practical problem.
Δ: There is a deposit. I can not use it.
X: Remarkably deposited. I can not use it.

  Table 2 shows the coating properties of the water-based coatings for metal packaging materials obtained in Examples 1 to 12 and Comparative Examples 1 to 4, and the evaluation results of the coating film properties obtained from these water-based coatings.

  As shown in Table 2, while the water-based coatings for metal packaging materials of Examples 1 to 12 all had good physical properties, the water-based coatings for metal packaging materials of Comparative Examples 1 to 4 were either of physical properties. However, it was not possible to obtain a product that was all good.

Claims (9)

An aqueous dispersion of an acrylic-modified epoxy resin (A), and an aqueous wax dispersion (B) having an average particle diameter of 0.01 to 15 μm,
The acrylic-modified epoxy resin (A) is a composite resin obtained by using an ethylenically unsaturated monomer (C) containing a carboxyl group-containing monomer and an epoxy resin (D),
The ethylenically unsaturated monomer (C) has a carboxyl group concentration of 2.7 to 7.1 mmol / g,
The weight ratio of the ethylenically unsaturated monomer (C) and the epoxy resin (D) is (C) / (D) = 10/90 to 50/50,
Viscosity eta _H at a shear rate 10000s ^-1 at 25 ° C. is 20~100mPa · s, and a viscosity eta _L at a shear rate of 0.1s ^-1, the ratio of the viscosity eta _H at a shear rate of 10000s ^-1 eta _L / (eta) _H is 1-8, The water-based coating material for metal packaging materials characterized by the above-mentioned. The surface tension is 25 to 33 mN / m, the water-based paint for metal packaging materials according to claim 1 . The organic solvent comprising an alkyl alcohol is a C1-10 alkylene glycol monoalkyl ethers and alkyl group is 1-6 carbon atoms alkyl group (E), according to claim 1 or 2, wherein containing 5-30 wt% Water-based paint for metal packaging materials. The aqueous wax dispersion (B) includes an aqueous wax dispersion (b2) that is an emulsified dispersion of an aqueous medium and a wax, and the wax is added to 100 parts by weight of the acrylic-modified epoxy resin (A). The water-based coating material for metal packaging materials according to any one of claims 1 to 3, comprising 0.1 to 10 parts by weight. An aqueous dispersion of an acrylic-modified epoxy resin (A), and a method for producing a water-based coating for a metal packaging material, comprising mixing an aqueous wax dispersion (B) having an average particle diameter of 0.01 to 15 μm.
  The acrylic-modified epoxy resin (A) is a composite resin in which an ethylenically unsaturated monomer (C) containing a carboxyl group-containing monomer and an epoxy resin (D) are reacted.
The ethylenically unsaturated monomer (C) is blended so that the carboxyl group concentration is 2.7 to 7.1 mmol / g,
The weight ratio of the ethylenically unsaturated monomer (C) and the epoxy resin (D) is used so that (C) / (D) = 10/90 to 50/50,
The aqueous wax dispersion (B) includes an aqueous wax dispersion (b1) in which the wax is emulsified and dispersed in an aqueous medium in the presence of a resin having an acid value of 100 to 500 mgKOH / g and a number average molecular weight of 2000 to 50000,
The water-based paint for metal packaging materials has a shear rate of 10,000 s at 25 ° C. ^-1 Viscosity at _H Is 20 to 100 mPa · s, and the shear rate is 0.1 s. ^-1 Viscosity at _L And a shear rate of 10,000 s. ^-1 Viscosity at _H Ratio η _L / Η _H The manufacturing method of the water-based coating material for metal packaging materials whose is 1-8. The said wax aqueous dispersion (B) contains the wax aqueous dispersion (b2) which disperse | distributes a wax in an aqueous medium in absence of surfactant, The manufacture of the water-based coating material for metal packaging materials of Claim 5 Way . The manufacturing method of the water-based coating material for metal packaging materials of Claim 5 or 6 which contains the said wax 0.1-10 weight part with respect to 100 weight part of said acrylic modified epoxy resins (A) . The water-based coating material for metal packaging materials of any one of Claims 1-4 containing a phenol resin or an amino resin. The metal packaging material which has a coating film layer which is a hardened | cured material of the aqueous coating material for metal packaging materials of any one of Claims 1-4 and 8 on a metal plate.