JP2007044883A - Resin coated metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin coated metal sheet having a resin film showing high corrosion resistance and ablation resistance and also further showing other characteristics, for example, high tape peeling resistance. <P>SOLUTION: The resin coated metal sheet has the resin film obtained from an emulsion resin composition and an epoxy type external crosslinking agent. The emulsion resin composition contains scaly silica with a mean particle size of 0.08-1.0 μm treated with a cationic surfactant and an ethylenic/unsaturated carboxylic acid copolymer and the ethylene/unsaturated carboxylic acid copolymer is neutralized with a tertiary amine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin-coated metal plate, particularly a resin-coated metal plate having excellent corrosion resistance and abrasion resistance.

  As materials used for automobiles, home appliances, and building materials, zinc-plated steel sheets such as electrogalvanized steel sheets and hot-dip galvanized steel sheets, or inorganic materials that have been chromated on the galvanized steel sheets for the purpose of further improving corrosion resistance Many surface-treated steel sheets are used. However, due to the recent increase in environmental awareness, there is an increasing demand for steel sheets not subjected to chromate treatment.

  As means for improving corrosion resistance in place of such chromate treatment, for example, Patent Document 1 discloses that an emulsion resin composition containing a specific amino alcohol and an ethylene-unsaturated carboxylic acid copolymer is formed on a resin-coated metal sheet. Proposed to be used to.

In order to improve the corrosion resistance and abrasion resistance of the resin-coated metal plate, silica is also included in the resin film. Among these silicas, Patent Document 2 proposes to use scaly silica, and Patent Document 3 proposes to use scaly silica treated with a cationic surfactant or an amine-based alkaline substance.
JP 2002-326310 A JP 2004-322573 A JP 2002-348538 A

  However, recently, a high degree of corrosion resistance has been required even for resin films that are not subjected to chromate treatment. Accordingly, the problem to be solved by the present invention is to provide a resin-coated metal plate provided with a resin film that exhibits more excellent corrosion resistance and abrasion resistance and can exhibit further other characteristics such as excellent tape peel resistance. There is.

  The resin-coated metal plate of the present invention that has solved the above-mentioned problems is a resin-coated metal plate provided with a resin film obtained from an emulsion resin composition and an epoxy-based external cross-linking agent, and the emulsion resin composition The product contains scaly silica having an average particle size of 0.08 to 1.0 μm treated with a cationic surfactant and an ethylene-unsaturated carboxylic acid copolymer, and the ethylene-unsaturated carboxylic acid copolymer The polymer is neutralized with a tertiary amine.

The scaly silica content of dry resin film in the desirably a 60~180mg / m ^2. Further, when non-flaky silica is further contained, the total content of the flake silica and the non-flaky silica in the dry resin film is preferably 120 to 240 mg / m ² .

  In a preferred embodiment of the present invention, the emulsion resin composition has a boiling point of 100 ° C. or lower corresponding to 0.2 to 0.8 mol with respect to 1 mol of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer. An internal cross-linking agent containing a tertiary amine and a basic compound of a Group 1 element corresponding to 0.02 to 0.4 mol and having two or more functional groups capable of reacting with a carboxyl group, It contains 1 to 20% by mass with respect to 100% by mass of the solid content of the unsaturated carboxylic acid copolymer, and is substantially free of amine and ammonia having a boiling point exceeding 100 ° C. As a result, various properties such as adhesion to other coating films, lubricity, workability, and grounding properties can be provided, and a resin film having excellent corrosion resistance and tape peel resistance after the degreasing process is formed. be able to.

  The ethylene-unsaturated carboxylic acid copolymer is preferably a copolymer in which 10 to 40% by mass of an unsaturated carboxylic acid is copolymerized when the total monomer amount of the copolymer is 100% by mass, It is more preferable that the copolymer is 15 to 25% by mass. In another preferred embodiment of the present invention, the tertiary amine is triethylamine.

The emulsion resin composition may contain 5 to 40% by mass of non-flaky silica having an average particle diameter of 1 to 200 nm in 100% by mass of the solid content, and 0.5 to 20% by mass of spherical polyethylene wax. It is also desirable that it be included. A preferred embodiment of the present invention is a resin-coated metal plate in which the resin film is provided on one or both surfaces of a metal plate, and the amount of the resin film attached is 0.4 to 2.5 g / m ² in dry mass. It is.

  According to the present invention, a resin-coated metal plate excellent in corrosion resistance and abrasion resistance can be obtained. Furthermore, in a preferred embodiment of the present invention, by adjusting the components in the emulsion resin composition and the composition thereof, it is possible to give the film of the resin-coated metal sheet more preferable properties such as tape peel resistance.

BEST MODE FOR CARRYING OUT THE INVENTION

  The resin-coated metal plate of the present invention is provided with a resin film formed from a specific emulsion resin composition on at least one surface of the metal plate. In the present invention, the metal plate is not particularly limited, and examples thereof include zinc or a zinc-based plated steel plate, an aluminum plate, an aluminum-based alloy plate, and a titanium plate. These metal plates may be subjected to a known rust preventive ground treatment such as phosphate treatment or other ground treatment, and a resin film may be formed thereon. From the viewpoint of environmental problems, it is preferable not to perform chromate treatment.

  The resin-coated metal plate of the present invention is characterized in that the emulsion resin composition forming the resin film contains scaly silica having an average particle diameter of 0.08 to 1.0 μm treated with a cationic surfactant. One of them. The scaly silica contained in the emulsion resin composition is disposed in layers in the resin film during the coating and drying process of the composition. The scaly silica arranged in layers exhibits a high barrier property that effectively shields water and oxygen, improves the corrosion resistance of the resin-coated metal plate, and also provides excellent abrasion resistance. Here, the scaly silica in the present invention refers to a silica having an aspect ratio (ratio of major axis to thickness of silica particles) of 10 or more and a thin and flat shape. On the other hand, silica having a spherical shape or the like that does not take such an aspect ratio is referred to as non-flaky silica in the present invention. The lower limit of the preferred aspect ratio of the scaly silica is 20, and the preferred upper limit is 80, more preferably 40.

  In the present invention, scaly silica treated with a cationic surfactant is used. This is because the emulsion resin composition of the present invention is characterized by containing an ethylene-unsaturated carboxylic acid copolymer neutralized with a tertiary amine. This is because gelation occurs when scaly silica not treated with a surfactant is added. The scaly silica treated with the cationic surfactant refers to scaly silica that is preliminarily mixed with the cationic surfactant before mixing with the ethylene-unsaturated carboxylic acid copolymer. The scaly silica treated with such a cationic surfactant is sold, for example, under the trade name of “Sunlably (registered trademark) LFS HB-010SN” by Dokai Chemical Industries, Ltd.

  In consideration of peeling resistance, weldability, cost, etc. when processing a resin-coated metal plate, it is desirable that the resin film be as thin as possible. In order to exhibit a high barrier property by arranging in a layer form even in such a thin resin film, scaly silica having a small average particle diameter is preferred. Therefore, in the present invention, scaly silica having an average particle diameter of 0.08 to 1.0 μm is used. In addition, the value of the average particle diameter of scaly silica is measured by a dynamic light scattering method. The upper limit of the average particle diameter of scaly silica is preferably 0.5 μm, more preferably 0.25 μm or less, and the lower limit is preferably 0.1 μm, more preferably 0.15 μm or more.

The scale-like silica content in the dry resin film is 60 mg / m in order to improve the corrosion resistance, abrasion resistance, and coating film adhesion of the resin-coated metal sheet by arranging the scale-like silica without defects in the resin film. It is preferably ² or more. More preferably, it is 90 mg / m < ² > or more, More preferably, it is 120 mg / m < ² > or more. However, from the viewpoint of cost and the like, the scaly silica content is preferably 180 mg / m ² or less, more preferably 150 mg / m ² or less.

Furthermore, the emulsion resin composition in the present invention may contain non-flaky silica in addition to flaky silica. When non-flaky silica is also included, the total content of flaky silica and non-flaky silica in the dry resin film is preferably 120 mg / m ² or more. More preferably, it is 150 mg / m ² or more. On the other hand, the preferable upper limit of the total content of scaly silica and non-flaky silica is 240 mg / m ² , more preferably 180 mg / m ² or less.

  The present invention is characterized in that the emulsion resin composition contains an ethylene-unsaturated carboxylic acid copolymer neutralized with a tertiary amine. By using such a composition containing a resin neutralized with a tertiary amine in combination with an epoxy external crosslinking agent, a resin film having excellent corrosion resistance and abrasion resistance can be formed.

  Epoxy-based external crosslinking agents are not particularly limited, but sorbitol polyglycidyl ether, (poly) glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, (poly) ethylene Suitable examples include polyglycidyl ethers such as glycol diglycidyl ether and glycidyl group-containing crosslinking agents such as polyglycidyl amines, and one or more of these can be used.

  The emulsion resin composition used in the present invention preferably contains 50 to 90% by mass of an ethylene-unsaturated carboxylic acid copolymer (including a neutralized state) in terms of solid content. In the present invention, a preferable emulsion resin composition includes a tertiary amine having a boiling point of 100 ° C. or less corresponding to 0.2 to 0.8 mol with respect to 1 mol of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer. And an internal cross-linking agent having two or more functional groups capable of reacting with a carboxyl group, and a solid content of the emulsion resin composition 100. It contains 1 to 20% by mass with respect to mass%, and is substantially free of amine and ammonia having a boiling point of over 100 ° C.

The ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and an ethylenically unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, itaconic acid, and the like. A copolymer can be obtained by polymerizing with. As the copolymer, a random copolymer is most preferable, but a block copolymer or a copolymer in which an unsaturated carboxylic acid moiety is grafted may be used. In addition, (meth) acrylic acid is suitable as the unsaturated carboxylic acid. Further, in place of a part of ethylene, an olefin monomer such as propylene or 1-butene may be used, and other known vinyl monomers are partially copolymerized as long as the object of the present invention is not impaired. (About 10 mass% or less).

  The copolymerization ratio of unsaturated carboxylic acid to ethylene is preferably 10 to 40% by mass of unsaturated carboxylic acid when the total amount of monomers of the copolymer is 100% by mass. When the amount of unsaturated carboxylic acid is less than 10% by mass, the film strengthening effect is not exhibited due to the small number of carboxyl groups serving as a base point for intermolecular association by ion clusters or a cross-linking point with a cross-linking agent. The corrosion resistance after the degreasing step may be lowered, and the emulsion stability of the emulsion resin composition is inferior, which is not preferable. A more preferable lower limit of the unsaturated carboxylic acid is 15% by mass. On the other hand, when the unsaturated carboxylic acid exceeds 40% by mass, the corrosion resistance and water resistance of the resin film are lowered, and the corrosion resistance after the degreasing process is also lowered, which is not preferable. A more preferred upper limit is 25% by mass.

  Since the ethylene-unsaturated carboxylic acid copolymer has a carboxyl group, it is emulsified (water dispersion) by neutralization with a tertiary amine or tertiary amine and other bases (such as NaOH). can do. In a preferred embodiment of the present invention, a tertiary amine having a boiling point of 100 ° C. or lower is used. Amines having a boiling point exceeding 100 ° C. are likely to remain on the steel sheet when the resin film is dried, and the water absorption of the resin film increases, leading to a decrease in corrosion resistance. Therefore, the emulsion resin composition used for film formation in the present invention does not contain amines having a boiling point higher than 100 ° C. Also, ammonia was not included because the effect of adding ammonia was not recognized. As the boiling point, a boiling point under atmospheric pressure is adopted.

  Specific examples of the tertiary amine having a boiling point of 100 ° C. or lower include triethylamine, N, N-dimethylbutylamine, N, N-dimethylallylamine, N-methylpyrrolidine, tetramethyldiaminomethane, trimethylamine and the like. Two or more kinds can be mixed and used. Most preferred among these is triethylamine.

  The amount of the tertiary amine having a boiling point of 100 ° C. or less is in the range of 0.2 to 0.8 mol (20 to 80 mol%) with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. It is preferable. This is because within this range, the tape peel resistance is good and the corrosion resistance is further improved. If the tertiary amine having a boiling point of 100 ° C. or less is less than 0.2 mol, it is considered that the particle size of the resin particles in the emulsion is increased and the effect of improving the corrosion resistance and the like is lowered. In addition, use of a tertiary amine having a boiling point of more than 0.8 mol and a boiling point of 100 ° C. or less is not preferable because the emulsion resin composition may thicken and gel. A more preferable upper limit of the amount of the tertiary amine is 0.6 mol, further preferably 0.5 mol, and a more preferable lower limit of the amount of the tertiary amine is 0.3 mol.

  In a preferred embodiment of the invention, basic compounds of group 1 elements are also used for neutralization. This is effective in improving solvent resistance and film hardness. Accordingly, a basic compound of a Group 1 element is added to a preferred emulsion resin composition. The basic compound of the Group 1 element preferably contains one or more metals selected from sodium, potassium, and lithium, and a hydroxide, carbonate, or oxide of these metals is preferable. Among these, NaOH, KOH, LiOH and the like are preferable, and NaOH has the best performance and is preferable. In addition, since the effect of adding a basic compound of Group 2 or higher is not recognized, the emulsion resin composition used for film formation in the present invention contains an ethylene-unsaturated carboxylic acid copolymer. It is preferred that no basic compounds of group 2 or higher for the reaction partner of the polymer are included.

  The amount of the basic compound of the Group 1 element is in the range of 0.02 to 0.4 mol (2 to 40 mol%) with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. It is preferable to do. When the amount of the basic compound of the Group 1 element is less than 0.02 mol, the emulsion stability becomes insufficient. Conversely, when the amount exceeds 0.4 mol, the hygroscopicity of the resulting resin film (especially with respect to an alkaline solution). ) Is increased, and the corrosion resistance after the degreasing step is decreased, which is not preferable. More preferably, the lower limit of the basic compound amount of the Group 1 element is 0.03 mol, and a more preferable lower limit is 0.1 mol, and the more preferable upper limit of the amount of the basic compound of the Group 1 element is 0.3 mol, A preferable upper limit is 0.2 mol.

  The preferred ranges of the respective amounts of the tertiary amine having a boiling point of 100 ° C. or less and the basic compound of the Group 1 element are as described above, and these are all ethylene-unsaturated carboxylic acid copolymers. Used to neutralize the carboxyl group in the emulsion and emulsify. Therefore, if the total amount used is too large, the viscosity of the emulsion resin composition may rapidly increase and solidify, and a great deal of energy is required to volatilize excess alkali which may cause a decrease in corrosion resistance. Since it is necessary, it is not preferable. However, if the neutralization amount is too small, the emulsifiability is inferior, which is not preferable. Therefore, the total amount of the tertiary amine having a boiling point of 100 ° C. or less and the basic compound of the Group 1 element is 0.3 to 0 with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. It is preferable to be in the range of .85 mol.

  The emulsion resin composition used in a preferred embodiment of the present invention is obtained by emulsifying a tertiary amine having a boiling point of 100 ° C. or less and a basic compound of a Group 1 element in combination, whereby resin particles in the composition are obtained. It exists stably in an aqueous medium in the form of extremely small fine particles (oil droplets) of 5 to 50 nm. For this reason, it is presumed that the film forming property of the resulting resin film, the adhesion to the metal plate, and the densification of the film are achieved, and the corrosion resistance and tape peel resistance are improved. The aqueous medium may contain a hydrophilic solvent such as alcohol or ether in addition to water. The particle size of the resin particles in the emulsion can be measured, for example, by a laser diffraction method using a light scattering photometer (manufactured by Otsuka Electronics, etc.).

  In the neutralization step (emulsification step) of the ethylene-unsaturated carboxylic acid copolymer with a tertiary amine having a boiling point of 100 ° C. or lower and a basic compound of a Group 1 element, a tertiary amine having a boiling point of 100 ° C. or lower and It is desirable to add the basic compound of Group 1 element to the copolymer almost simultaneously, or to add a tertiary amine having a boiling point of 100 ° C. or lower first. The reason is not clear, but if a tertiary amine having a boiling point of 100 ° C. or lower is added later, the effect of improving corrosion resistance and tape peel resistance may be insufficient.

  The ethylene-unsaturated carboxylic acid copolymer having a carboxyl group neutralized with a tertiary amine having a boiling point of 100 ° C. or less and a basic compound of a Group 1 element forms an intermolecular association by an ion cluster (ionomer). ), And forms a resin film having excellent corrosion resistance and tape peel resistance. However, in order to form a tougher film, it is desirable to crosslink the polymer chains by chemical bonding utilizing a reaction between functional groups.

  Therefore, a preferable emulsion resin composition of the present invention contains an internal crosslinking agent having two or more functional groups capable of reacting with a carboxyl group. The preferable amount is 1 to 20% by mass with respect to 100% by mass of the solid content of the ethylene-unsaturated carboxylic acid copolymer. When the amount is less than 1% by mass, the effect of crosslinking by chemical bonding becomes insufficient, and the effect of improving the corrosion resistance and tape peel resistance is hardly exhibited. On the other hand, when it exceeds 20% by mass, the crosslink density of the resin film becomes excessively high, the hardness increases, and it becomes impossible to follow the deformation at the time of press working, resulting in cracks, resulting in corrosion resistance and coating. This is not preferable because film adhesion is lowered. A more preferable amount of the internal crosslinking agent is 5 to 10% by mass with respect to 100% by mass of the solid content of the ethylene-unsaturated carboxylic acid copolymer.

  The internal crosslinking agent is not particularly limited, but 4,4′-bis (ethyleneiminecarbonylamino) diphenylmethane, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N′— Bifunctional aziridine compounds such as diphenylmethane-4,4′-bis (1-aziridinecarboxamide), toluenebisaziridinecarboxyamide; tri-1-aziridinylphosphine oxide, tris [1- (2-methyl) aziridinyl] phosphine Oxide, trimethylolpropane tris (β-aziridinylpropionate), tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tetramethylpropanetetraaziridinylpropionate, etc. A tri- or higher functional aziridine compound or a derivative thereof The cited as a preferred example aziridinyl group-containing crosslinking agent, there can be used one or two or more of them. In addition, you may use together polyfunctional aziridine and monofunctional aziridine (ethyleneimine etc.).

  In a preferred embodiment of the present invention, it is preferable to further use an epoxy-based external crosslinking agent in an amount of 1 to 20% by mass relative to 100% by mass of the solid content of the emulsion resin composition. A more preferable lower limit of the external crosslinking agent is 5% by mass, and a more preferable upper limit is 10% by mass.

  You may make the emulsion resin composition used by this invention contain 10-30 mass% non-flaky silica in conversion of solid content. This is effective in improving corrosion resistance, coating film adhesion, wrinkle resistance, and the like, and is also effective in improving corrosion resistance and tape peel resistance after the degreasing process. When the amount of non-flaky silica is less than 10% by mass, these effects are hardly exhibited. Conversely, if the amount of non-flaky silica exceeds 30% by mass, the proportion of non-flaky silica becomes excessively high and the film-forming property is lowered, and the resin film may be cracked during the drying step. Unfavorable because it leads to a decrease in corrosion resistance. Further, non-flaky silica will act as a polishing agent, increasing the lubricity of the film, lowering the coefficient of friction, and causing wear of the mold during processing. Will shorten the lifespan. The lower limit of the more preferable amount of non-flaky silica is 15% by mass, and the upper limit is 20% by mass.

  In order to obtain the maximum effect of the non-flaky silica as described above, it is preferable that the average particle diameter of the non-flaky silica is in the range of 1 to 200 nm. The smaller the particle size of the non-flaky silica, the better the corrosion resistance of the film. This is considered to further increase the corrosion resistance by densifying the resin film and improving the adhesion. From this point of view, the smaller the particle size of the non-flaky silica, the better. However, when the particle size is extremely small, the effect is saturated, and therefore the lower limit of the particle size is preferably 1 nm. On the other hand, when the particle size of the non-flaky silica exceeds 200 nm, the surface of the resin film is roughened and a dense resin film cannot be formed, and the non-flaky silica acts as a polishing agent, Since it leads to deterioration of workability, it is not preferable. From the viewpoint of production cost and corrosion resistance, non-flaky silica having an average particle diameter of 4 to 20 nm, more preferably 4 to 50 nm is more preferably used.

  As the non-flaky silica in the present invention, for example, “XS”, “SS”, “40”, “N”, “UP”, etc. of “Snowtex” series (colloidal silica manufactured by Nissan Chemical Industries) are preferably used. Can do.

  The emulsion resin composition of the present invention may contain a wax in a range of 0.5 to 20% by mass in terms of solid content. The wax is effective in improving the lubricity and scratch resistance of the resulting resin film. Furthermore, it is preferable to improve the deep drawability and punchability required during press working and punching, wear resistance of the mold, blackening resistance of the sliding surface during processing, and impart excellent workability. It is what is used.

  When the amount of the wax is less than 0.5% by mass in terms of solid content, the resulting resin film has insufficient lubricity, and it is impossible to improve the scratch resistance and to obtain satisfactory processability. On the other hand, if it exceeds 20% by mass, the resulting resin film has sufficient lubricity, but it adheres to other coatings when electrodeposition coating, powder coating, or post-coating by silk printing is applied. Inferior to sex. Moreover, the corrosion resistance and tape peeling resistance after a degreasing process also fall. This is because the wax softens, liquefies, or blooms due to heating in the post-coating process and changes over time, and the wax is concentrated at the interface between the resin film and the post-coating film, or between the metal plate and the resin film. Therefore, it is considered that the adhesion with other coating films of the post-coating and the adhesion with the metal plate are deteriorated. A more preferable upper limit of the wax is 10% by mass, and a further preferable upper limit is 5.0% by mass.

  The wax is not particularly limited, and natural wax, synthetic wax, a mixture thereof and the like can be used. As natural waxes, for example, carnauba wax, rice wax, candelilla wax, montan wax and derivatives thereof, mineral oil wax, microcrystalline wax, paraffin wax and the like, and derivatives having a carboxyl group added thereto may also be used. it can.

  Synthetic waxes include polyethylene, polyethylene oxide, polypropylene, ethylene and propylene copolymer wax, and oxide wax of copolymer wax of ethylene and other monomers. This system can be used in various ways including terpolymer systems by changing the copolymerization partner. Furthermore, maleic acid addition wax, fatty acid ester type and the like can be mentioned. In addition, waxes of fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and tetrafluoroethylene can be used.

  As the wax, it is preferable to select a wax having a softening point of 80 to 140 ° C. among those exemplified above. When the softening point is lower than 80 ° C., the wax particles soften or liquefy as the mold temperature rises during press working or punching, and liquefaction occurs on the sliding surface between the resin-coated steel sheet and the mold. This is not preferable because a wax breakage phenomenon occurs, processability is reduced, and scuffing or seizure with a mold occurs. In addition, blackened material may adhere to the sliding portion and the product appearance may be significantly deteriorated. Furthermore, it turned out that it is unpreferable if a softening point is too low also from a viewpoint of the corrosion resistance after a degreasing process, and tape-peeling-proof property. On the other hand, when the softening point exceeds 140 ° C., the lubricity by the wax becomes insufficient, and there is no improvement in punchability, die wear resistance, deep drawability, etc., and the corrosion resistance after the degreasing process is slightly lowered. The tendency to do was seen.

  As the wax, spherical polyethylene wax is most preferable. In this case, in order to obtain the maximum effect of the spherical polyethylene wax, the particle diameter of the wax particles is preferably 0.1 to 3 μm. If the particle size of the wax particles is smaller than 0.1 μm, it is difficult to achieve significant improvements in lubricity, punchability, mold wear resistance and deep drawability. On the other hand, when the particle size of the wax particles exceeds 3 μm, it is difficult to uniformly disperse in the finely divided emulsion resin composition, so that the adhesion of the resin film to the metal plate may be lowered. . A more preferable spherical polyethylene wax has a particle size of 0.3 to 1.0 μm.

  As the spherical polyethylene wax as described above, for example, “Daijet E-17” (manufactured by Reciprocal Chemical), “KUE-1”, “KUE-5”, “KUE-8” (manufactured by Sanyo Chemical Industries), “ "C-100", "W-200", "W-300", "W-400", "W-500", "W-640", "W-700" of "Chemical Pearl" series (Mitsui Chemicals) Or a commercially available product such as “Elepon E-20” (manufactured by Nikka Chemical) can be suitably used.

  The emulsion resin composition in a preferred embodiment of the present invention comprises an ethylene-unsaturated carboxylic acid copolymer, a tertiary amine having a boiling point of 100 ° C. or less, a basic compound of a Group 1 element, an internal crosslinking agent such as an aziridine compound, Further, non-flaky silica, wax and the like used as necessary are included. The amount of the crosslinking agent, scaly and non-flaky silica, wax, etc. is adjusted so that the ethylene-unsaturated carboxylic acid copolymer (that is, this resin component) is 50% by mass or more of the solid content of the emulsion resin composition. It is desirable to adjust.

  The emulsion resin composition is prepared by first charging the ethylene-unsaturated carboxylic acid copolymer together with an aqueous medium into, for example, a homogenizer device, heating to 70 to 250 ° C. as necessary, and having a boiling point of 100 ° C. or less. A tertiary amine and a basic compound of a Group 1 element are appropriately added in the form of an aqueous solution or the like (a tertiary amine having a boiling point of 100 ° C or lower is added first, or a tertiary amine having a boiling point of 100 ° C or lower and The basic compound of the Group 1 element is added almost simultaneously) and stirred with a high shearing force. Non-flaky silica, wax, cross-linking agent, etc. may be added at any stage, but after adding the cross-linking agent, do not apply heat as much as possible to prevent gelation due to the progress of the cross-linking reaction. It is desirable.

  The emulsion resin composition includes a diluent, an anti-skinning agent, a leveling agent, an antifoaming agent, an emulsifier, an emulsifying agent, a film-forming aid, a color pigment, a thickener, and the like within a range that does not impair the object of the present invention. Silane coupling agents and other resins may be added as appropriate.

  In order to form a resin film on a metal plate, the emulsion resin composition is applied to one or both surfaces of the metal plate surface using a known coating method, that is, a roll coater method, a spray method, a curtain flow coater method, or the like. What is necessary is just to apply | coat and heat-dry. The heating and drying temperature is preferably a temperature at which the crosslinking reaction between the crosslinking agent and the carboxyl group proceeds. When a spherical polyethylene wax is used as the lubricant, the temperature below the softening point of the wax, for example, 70 to 130 ° C., in order to maintain the spherical shape of the wax and improve the workability in the subsequent processing step. It is desirable to carry out heat drying in the range.

The adhesion amount of the resin film is preferably 0.4 to 2.5 g / m ² in terms of dry mass. When the adhesion amount is less than 0.4 g / m ^2, it is difficult to uniformly apply to the metal plate, and it is difficult to sufficiently exhibit the effects of corrosion resistance and anti-abrasion property. However, if the adhesion amount exceeds 2.5 g / m ² , the conductivity and the coating film adhesion may be reduced. Furthermore, the amount of peeling of the resin film is increased during press working, causing adhesion and accumulation of the peeling film on the mold, resulting in trouble with press molding and wasteful manufacturing cost. The lower limit of the more preferable resin film adhesion amount is 0.5 g / m ² , and the upper limit is 2.0 g / m ² .

  The resin-coated metal plate of the present invention is obtained by forming a resin film. This resin-coated metal plate may be used as it is after the processing step depending on the application, or may be used after being subjected to electrodeposition coating, powder coating or silk printing (about 130 to 160 ° C., about 20 to 30 minutes) under conventional conditions. Good.

[Evaluation methods]
(1) Corrosion resistance About the obtained resin-coated metal plate (steel plate), the salt spray test was implemented according to JISZ2371, and the time until 1% of white rust generate | occur | produced was measured.
(Evaluation criteria)
◎: 264 hours or more ○: 240 hours or more to less than 264 hours Δ: 168 hours or more to less than 240 hours × 168 hours or less

(2) Ablation resistance The obtained resin-coated metal plate (steel plate) is cut into 100 mm squares, and holes of φ6 mm are provided at the four corners so that they can be set through a pin on a vibration generator (made by IDEC: “BF-500UC”). I opened it. In order, vibration is generated by placing silicone rubber, test steel plate with resin film on top, cardboard cut to 60 mm square (K5, B flute), silicone rubber and 2 kg weight (see Fig. 1). After the apparatus was vibrated for 5 minutes (amplitude 0.5 mm, acceleration 1.2 G, 30 Hz), the appearance of the test steel sheet was evaluated according to the following criteria.
(Evaluation criteria)
◎: No damage to the film ○: Damage to the film, but no damage to the galvanized surface △: Damage to the galvanized surface that can be visually confirmed ×: Significant damage to the galvanized surface

(3) Paintability (coating adhesion)
The obtained resin-coated metal plate (steel plate) was bar-coated with an acrylic paint so that the coating thickness was about 20 μm, and baked at a temperature of 150 ° C. for 20 minutes for post-coating. Subsequently, after 100 mm of 1 mm square grids were cut into this test steel plate with a cutter knife and extruded 6 mm with an Erichsen tester, a tape peeling test was carried out on the basis of the number of remaining squares of the coating film. The paintability (coating film adhesion) was evaluated in 5 stages.
(Evaluation criteria)
5: 100% coating film remaining rate
4: Coating film residual ratio 90-99%
3: Coating film residual ratio 80-89%
2: Coating film residual ratio 70-79%
1: Less than 70% remaining film ratio

(4) Degreasing resistance (corrosion resistance after degreasing process)
The resin-coated steel sheet is dipped in 20 g / liter of an alkaline degreasing agent (manufactured by Nihon Parkerizing: “CL-N364S”) prepared at 60 ° C. for 2 minutes, then pulled up, washed with water, dried, and then subjected to a salt spray test in accordance with JIS Z2371. The time until 1% of white rust was generated was measured.
(Evaluation criteria)
◎: 240 hours or more ○: 120 to less than 240 hours Δ: 72 to less than 120 hours ×: less than 72 hours

(5) Tape peel resistance An adhesive tape (manufactured by Sliontec: “Flamen Tape No. 9510”, rubber adhesive) is applied to the obtained resin-coated metal plate (steel plate), and the temperature is kept at 40 ° C. with a constant temperature and humidity device. After storing for 24 hours in an atmosphere of 98% RH, the tape was peeled off according to JIS K5400, and the remaining area ratio of the film was measured.
(Evaluation criteria)
A: Film remaining rate 100%
○: Remaining film ratio 90-99%
Δ: film remaining ratio 89-70%
×: film remaining rate of less than 70%

(6) Coefficient of dynamic friction In order to evaluate the lubricity of the obtained resin-coated metal plate (steel plate), the load due to sliding when the applied pressure is 5.4 MPa and the drawing speed is 300 mm / min using a sliding test device. And the dynamic friction coefficient was calculated.

Example 1 (Influence of base and scale-like silica type)
In order to prepare the emulsion resin composition, 626 parts by mass of water (hereinafter, simply referred to as “parts”) and 160 parts of an ethylene-acrylic acid copolymer (acrylic acid 20% by mass, melt index (MI) 300) are prepared in an autoclave. In addition, 40 mol% of triethylamine or ammonia (ratio to the number of moles of carboxyl groups of the ethylene-acrylic acid copolymer, the same applies to the base hereinafter) and 15 mol% of NaOH were added at 150 ° C, The mixture was stirred at high speed in an atmosphere of atmospheric pressure to obtain an ethylene-acrylic acid copolymer emulsion. Subsequently, 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane (manufactured by Nippon Shokubai: “Chemite (registered trademark) DZ-22E”, hereinafter abbreviated as “DZ-22E”) is used as an internal cross-linking agent in the emulsion. In addition, 5% by mass (in terms of solid content of ethylene-acrylic acid copolymer, the same applies to the internal cross-linking agent) is added as a solid content, and scaly silica shown in Table 1 (“Sun Lovely” (registered by Dokai Chemical Industries, Ltd.) (Trademark) LFS "series, hereinafter referred to as" HB-010SN "and other product numbers) is added in an amount of 15% by mass (in the amount of 100% by mass of the solid content of the emulsion resin composition, the same applies to silica) to give an emulsion. A resin composition was prepared.

Next, a glycidyl group-containing compound (manufactured by Dainippon Ink & Chemicals, Inc .: “Epicron (registered trademark) CR5L”; hereinafter abbreviated as “CR5L”) as an external crosslinking agent was added to the emulsion resin composition in an amount of 5% by mass (emulsion). The amount of the resin composition based on 100% by mass of the solid content, and the same applies to the external crosslinking agent).
The mixture of the emulsion resin composition and the external cross-linking agent was allowed to stand at room temperature for 7 days and examined for gelation. The results are shown in Table 1.

Example 2 (Influence of type and amount of scaly silica)
In order to prepare an emulsion resin composition, 626 parts of water and 160 parts of an ethylene-acrylic acid copolymer (acrylic acid 20 mass%, melt index (MI) 300) are added to an autoclave, and further, an ethylene-acrylic acid copolymer is added. 40 mol% of triethylamine and 15 mol% of NaOH are added to 1 mol of carboxyl group of the polymer, and the mixture is stirred at a high speed in an atmosphere of 150 ° C and 5 atm to prepare an ethylene-acrylic acid copolymer emulsion. Obtained. Subsequently, 4,5′-bis (ethyleneiminocarbonylamino) diphenylmethane (DZ-22E) as an internal cross-linking agent was added to the emulsion in an amount of 5% by mass, and non-flaky silica (“Snowtex” manufactured by Nissan Chemical Co., Ltd.) was added. 15 wt% of XS ") in solid, as well as the type and amount shown in Table 2 (the content in the composition (solids) 5-30% by weight, 30~180mg / m ² at a content in the coating) An emulsion resin composition was prepared by adding flaky silica.

Next, 5 mass% of a glycidyl group-containing compound (CR5L) as an external crosslinking agent was added to the emulsion resin composition as a solid content.
An electrogalvanized steel sheet is used as the metal plate, and the mixture of the emulsion resin composition and the external cross-linking agent is applied to the surface by bar coating, followed by heating and drying at a plate temperature of 90 ° C. for 1 minute, and the adhesion amount (dry mass) A resin-coated metal plate (steel plate) having a resin film of 0.6 g / m ² was prepared and evaluated for characteristics. The results are shown in Table 2.

Example 3 (Influence of base type and amount)
Examples, except that the types and amounts of amines or ammonia shown in Table 3 and the basic compounds of Group 1 elements were added, and that 15% by mass of scaly silica (HB-010SN) was added in solid content. Resin-coated metal plates (steel plates) were produced in the same manner as in Example 2, and the characteristics were evaluated. The results are shown in Table 3.

Example 4 (Influence of the amount of internal crosslinking agent)
Except for adding 4,4'-bis (ethyleneiminocarbonylamino) diphenylmethane (DZ-22E) in the amount shown in Table 4 and adding 15% by mass of scaly silica (HB-010SN) in solid content. In the same manner as in Example 2, a resin-coated metal plate (steel plate) was produced, and the characteristics were evaluated. The results are shown in Table 4.

Example 5 (Influence of the amount of flaky silica and non-flaky silica)
A resin-coated metal plate (steel plate) was prepared in the same manner as in Example 2 except that the amounts of flaky silica (HB-010SN) and non-flaky silica (“Snowtex XS” manufactured by Nissan Chemical Industries) were added. Fabricated and characterized. The results are shown in Table 5.

Example 6 (Influence of average particle diameter of non-flaky silica)
Except for adding 15% by mass of flaky silica (HB-010SN) in solid content and 15% by mass of non-flaky silica (Nissan Chemical “Snowtex” series) having an average particle size shown in Table 6 Produced a resin-coated metal plate (steel plate) in the same manner as in Example 2, and evaluated the characteristics. The results are shown in Table 6.

Example 7 (Influence of spherical polyethylene wax)
Examples, except that spherical polyethylene wax of the type and amount shown in Table 7 ("Chemical" series manufactured by Mitsui Chemicals) was further added, and 15 mass% of scaly silica (HB-010SN) was added in solid content. Resin-coated metal plates (steel plates) were produced in the same manner as in Example 2, and the characteristics were evaluated. The results are shown in Table 7.

It is a schematic sectional drawing of the apparatus which measures the abrasion resistance of a resin coating metal plate (steel plate).

Explanation of symbols

1 Resin-coated metal plate (steel plate)
2 Silicone rubber 3 Cardboard 4 Weight

Claims (9)

A resin-coated metal plate provided with a resin film obtained from an emulsion resin composition and an epoxy-based external crosslinking agent,
The emulsion resin composition contains scaly silica having an average particle size of 0.08 to 1.0 μm treated with a cationic surfactant, and an ethylene-unsaturated carboxylic acid copolymer,
A resin-coated metal sheet, wherein the ethylene-unsaturated carboxylic acid copolymer is neutralized with a tertiary amine. The scaly silica content of dry resin film is replaced by a resin coated metal sheet according to claim 1 which is 60~180mg / m ^2. 3. The resin-coated metal plate according to claim 1, further comprising non-flaky silica, wherein a total content of the scaly silica and the non-flaky silica in the dry resin film is 120 to 240 mg / m ^2. . The emulsion resin composition comprises a tertiary amine having a boiling point of 100 ° C. or lower corresponding to 0.2 to 0.8 mol, based on 1 mol of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer; And a basic compound of a Group 1 element corresponding to 02 to 0.4 mol,
Including 1 to 20% by mass of an internal crosslinking agent having two or more functional groups capable of reacting with a carboxyl group with respect to 100% by mass of the solid content of the ethylene-unsaturated carboxylic acid copolymer,
The resin-coated metal sheet according to any one of claims 1 to 3, which is substantially free of amine and ammonia having a boiling point exceeding 100 ° C.   The ethylene-unsaturated carboxylic acid copolymer is copolymerized with 10 to 40% by mass of an unsaturated carboxylic acid when the total amount of monomers of the copolymer is 100% by mass. The resin-coated metal plate according to crab.   The resin-coated metal plate according to any one of claims 1 to 5, wherein the tertiary amine is triethylamine.   The resin-coated metal sheet according to any one of claims 1 to 6, wherein 10 to 30% by mass of non-flaky silica having an average particle diameter of 1 to 200 nm is contained in 100% by mass of the solid content of the emulsion resin composition. .   The resin-coated metal sheet according to any one of claims 1 to 7, wherein 0.5 to 20% by mass of spherical polyethylene wax is contained in 100% by mass of the solid content of the emulsion resin composition. The resin according to any one of claims 1 to 8, wherein the resin film is provided on one side or both sides of a metal plate, and the adhesion amount of the resin film is 0.4 to 2.5 g / m ² by dry mass. Painted metal plate.

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