KR101114776B1 - Resin-coated metal sheet having an excellent film peeling resistance during roll forming - Google Patents

Abstract

The present invention is a resin film produced from the surface treatment composition, characterized in that the Sword rocker hardness of the resin film is 35 or more, and the indenter depth in the nanoscratch test is less than 0.3 μm. It relates to a resin-coated metal sheet comprising. The resin-coated metal sheet according to the present invention has the desired properties of the resin-coated metal sheet, such as corrosion resistance, and can cause less problems for roll forming operations.

Description

RESIN-COATED METAL SHEET HAVING AN EXCELLENT FILM PEELING RESISTANCE DURING ROLL FORMING}

The present invention relates to resin-coated metal sheets used in automobiles, household appliances and building materials, more specifically to resin-coated metal sheets having good corrosion resistance and excellent film peel resistance in roll forming.

As a building material, in view of corrosion resistance, a galvanized steel sheet such as an electrogalvanized steel sheet or a galvanized steel sheet has been used. Conventionally, chromate treatment was performed on the galvanized steel sheet for the purpose of further improving corrosion resistance. However, as environmental awareness increases in recent years, the demand for steel sheets not subjected to chromate treatment has increased.

As a means of improving the corrosion resistance replacing the chromate treatment, for example, Japanese Patent Laid-Open No. 2007-269018 proposes a surface treatment composition containing an olefin, an α, β-ethylenically unsaturated carboxylic acid, a copolymer emulsion, and a crosslinking agent.

The resin-coated metal sheet is work molded according to the use. For example, in a roll forming method suitable for the manufacture of an elongated cross-section member, the metal sheet is continuously passed through a plurality of pairs of rolls arranged in a row, and the molding is continuously performed to produce a plate having a cross section of a desired shape. do. In the roll forming process, coolant is supplied to the metal sheet surface to ensure lubricity and to remove heat generated by the forming operation. This cooling liquid is removed by wiping the surface of a metal sheet with a water removal pad before the process of cutting a molded article to a fixed size (water removal process).

In a process such as the above roll forming (molding speed 20 to 70 m / min) in which high pressure is applied to the working surface, when the elasticity of the resin film of the resin-coated metal sheet is insufficient, fragments of the resin film are removed from the surface of the metal sheet. May be peeled off. The peeled film chips are transferred into the coolant bath, where the film chips remain suspended in the liquid without being precipitated at the bottom of the bath because the resin film has a low specific gravity of about 1. The coolant reuse loop system is usually equipped with a filter. However, the filter is designed to capture galvanized chips and does not have a fine mesh capable of capturing the resin film chips. As a result, the resin film chip follows with the coolant to be reused. Thus, the resin film chips are stacked on the surface of the water removal pad in the water removal process. Friction between the deposited film chip and the surface of the molded part may cause abnormal noise and / or prevent the molded part from running at a constant speed under the water removal pad, which may cause problems such as errors in the shape and / or dimensions of the part. This occurs and results in low yields.

In order to solve the above problems, there have been attempts to increase the hardness of the film by mixing the inorganic component in the resin film. However, the resin film became more brittle as the concentration of the inorganic component increased, thus resulting in lower film peeling resistance of the film. Therefore, it is desired to form a resin film having a moderate level of hardness and not brittle.

It is an object of the present invention to provide a resin-coated metal sheet which has the required properties of the resin-coated metal sheet, such as corrosion resistance, while having less film peeling in roll forming and less difficulty in roll forming operations.

The resin-coated metal sheet having excellent film peel resistance in roll forming has a Sword Rocker hardness of a resin film of 35 or more and an indenter depth of penetration of less than 0.3 μm in a nanoscratch test. Resin-coated metal sheet comprising a resin film made from the resin. Detailed description of the method of measuring the Sword rocker hardness and the nanoscratch test will be described later.

The surface treatment composition contains (a) a resin component comprising an olefin-α, β-unsaturated carboxylic acid copolymer, an α, β-unsaturated carboxylic acid polymer and an oxazoline group-containing copolymer, and (b) colloidal silica. Based on 100 parts by weight of the total amount of the resin component and the colloidal silica, the amount of the resin component is preferably 70 to 90 parts by weight, and the amount of the colloidal silica is preferably 10 to 30 parts by weight. The resin component preferably contains an oxazoline group-containing copolymer in an amount of 1 to 9 parts by weight based on 100 parts by weight of the total amount of the olefin-α, β-unsaturated carboxylic acid copolymer and the α, β-unsaturated carboxylic acid polymer. Colloidal silicas preferably have a surface area average particle diameter of 4 to 20 nm.

An embodiment in which the glycidyl group-containing silane coupling agent is further contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the resin component and the colloidal silica, and metavanadate is further contained in an amount of 0.5 to 6 parts by weight. All of the following embodiments are more preferred embodiments of the present invention.

The coating weight of the resin film in the resin-coated metal sheet is 0.1 to 1 g / m ² (dry basis).

The resin film is preferably formed by applying the surface treatment composition to a metal sheet and heating to a sheet temperature (arrival temperature) of 120 to 180 ° C.

According to the present invention, it is possible to form a strong resin-coating having a well-balanced hardness and brittleness, thereby successfully improving the film peeling resistance of the film during roll forming. In particular, since the hardness of the resin film is represented by the Sword rocker hardness, the brittleness of the resin film is represented by the indentation depth of the indenter in the nanoscratch, and the range of these optimum values can be confirmed. The correlation between the amount and the parameter can be increased. As a result, deposition of the film chip on the surface of the water removal pad is almost eliminated in the roll forming process, which makes it possible to continuously maintain the roll forming process with high yield for a long time.

The present inventors have succeeded in forming a hard film and suppressing peeling of the film by adjusting the amount of the inorganic component more than the organic component in the resin film of the resin-coated metal sheet. The inventors have also concentrated on studies to improve the ease of roll forming of resin-coated metals, and have completed the present invention. EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention provides a resin-coated metal sheet comprising a resin film made from a surface treatment composition, wherein the resin film has a Sword Rocker hardness of 35 or more and an indenter depth of 0.3 μm or less in a nanoscratch test. It is about. This is based on the inventors' finding that the Sword Rocker hardness accurately indicates the hardness of the resin film, and that the indenter depth in the nanoscratch exactly indicates the brittleness of the resin film. In rigorous processes, such as roll forming, in which the film surface is subjected to repeated sliding movements of a multi-stage roll under high pressure, it is important to improve the film's strength by balancing the hardness and the odor of the film. Simply increasing the hardness of the film can produce a brittle film that easily peels off through repeated sliding movements. Resin films having Sword Rocker hardness and indenter depth of entry in the previously described range have well balanced hardness and odor. Therefore, the resin film becomes stronger and exhibits excellent film peeling resistance in the roll forming process.

Sword Rocker Hardness is the hardness specified in ASTM D2134-93, Sword Rocker Hardness Tester (Ueshima Seisakusho Co., Ltd. (currently not produced) and Tester Sankyo Co., Ltd.) Manufactured by Sangyo Co., Ltd., and manufactured by Japan and various companies outside of Japan). Sword rocker hardness is formally specified in JIS K5400-1959 (now obsolete). Sword rocker hardness is measured by causing the resin film to swing the pendulum (sword rocker) in a sample formed thereon, and the number of swing cycles is counted before the swing range is reduced to a predetermined value. On a hard material, the rocker pivots the most number of times before stopping, because the turning movement is less resistant as the force acting vertically downward relative to the film (weight of the rocker) and the reaction force (upward) of the film are balanced. to be. On soft materials, the rocker pivots less often before stopping, because the turning movement is more resistant as the reaction force of the film becomes smaller than the force acting vertically downward. According to the present invention, the resin film must have a Sword Rocker hardness of 35 or more, since the satisfactory film peeling resistance of the film cannot be obtained unless the resin film has a certain level of hardness.

Sword rockers have a structure in which two rings of the same shape and size arranged parallel to each other can move in a reciprocating turn as shown in FIGS. 4 is a side view of the sword rocker upon measurement. The test sheet of the test sheet fastener has a rectangular parallelepiped-shaped recess formed at the center thereof so that the test sheet can be located on the bottom of the recess and the sword rocker can pivot on it.

A method of measuring the sword rocker hardness according to JIS K5400-1959 will be described. First, the Sword Rocker is positioned above the horizontal surface, and the vertical stabilization weight is adjusted by the weight for vertical stabilization so that the vertical shaft lies in the vertical direction. The standard glass sheet is installed on the test sheet fixing mechanism, fixed by the test sheet fixing mechanism, and is a level indicator positioned on the sheet, and the sheet surface is horizontally oriented in the longitudinal direction and the lateral direction by the adjusting leg of the test sheet fixing mechanism. Adjusted. Then, the Sword Rocker is placed over the test seat, shaken to initiate the pivoting movement, and the windshield cover is placed on the Sword Rocker to observe the level indicator from the outside of the windscreen cover. The coefficient is set to zero if the bubble of the level rocker B of theword rocker is first concealed by the cover of B (start). Then, until the bubble of the level indicator C is first concealed by the cover, the coefficient is increased by one each time the rocker performs one round trip of the swing movement, taking the coefficient at this time as the sword rocker value. . The standard glass sheet has a Sword Rocker value of 50, so the slopes of the level indicators B and C are adjusted so that a Sword Rocker value of 50 ± 1 is obtained in five measurements. The vertical position of the periodic adjustment weight is adjusted so that the time taken during a 50 ± 1 cycle is 60 ± 5 seconds. The test sheet is then changed to a methyl methacrylate sheet (polymethyl methacrylate) and the slopes of the level indicators B and C are adjusted so that a value of 20 ± 1 is obtained for all five measurements. After repeating these operations, the level indicators B and C are fixed if the measurements of all standard sheets meet the previously described criteria. It is measured at a temperature of 20 to 23 ° C. and a relative humidity of 20 to 40%. The test sheet is then changed to the sample to be measured and the Sword Rocker value is measured by a method similar to that described previously. The number is set as n = 5, the Sword Rocker value is measured for each, and the average value of the three highest measurements among the five Sword Rocker values is taken as the final value. The final value is the Sword Rocker value of the sample, twice that value is the Sword Rocker hardness. It is measured at a temperature of 20 to 23 ° C. and a relative humidity of 20 to 40%.

Nanoscratch test is described next. The nanoscratch test is related to the brittleness of the resin film and also to the film peel resistance of the film in the roll forming process. In the present invention, the nanoscratch test was performed using a high load tribo indenter (manufactured by Hysitron). A spherical probe (84.5 μm in diameter, made of diamond) was used as the pressure tip. The indenter is positioned vertically on the sample measured under a load of 0.1 mN, and the pressure tip is moved horizontally at a distance of 100 μm at a scratch rate of 10 μm / sec while maintaining the load, while at the same time the depth of entry of the indenter into the resin film is measured It became. It is measured at a temperature of 20 to 23 ° C. and a relative humidity of 20 to 40%. According to the present invention, indentation depth of the indenter should be less than 0.3 μm in the nanoscratch test. Films exhibiting values exceeding 0.3 μm are brittle even when the Sword Rocker hardness is high, and are easy to peel off during the roll forming process, and thus are unsatisfactory in terms of film peel resistance of the film.

The components of the surface treatment composition which are preferably used to obtain a resin film that meets the requirements of the Sword rocker hardness and the entry depth of the indenter are described below.

[Resin component]

Surface treatment compositions used in the present invention include olefin-α, β-unsaturated carboxylic acid copolymers (hereinafter referred to herein as “olefin-acid copolymers”), α, β-unsaturated carboxylic acid polymers (hereinafter referred to as “ Carboxylic acid polymers ", and oxazoline group-containing copolymers capable of crosslinking with these resins. In addition, the "α, β-unsaturated carboxylic acid" in the present invention also includes "α, β-unsaturated carboxylate" in which a part of the carboxyl groups are neutralized with the neutralizing agent described herein.

In the present invention, the "olefin-α, β-unsaturated carboxylic acid copolymer" or "olefin-acid copolymer" is a copolymer of olefin and α, β-unsaturated carboxylic acid, and the amount of the structural unit derived from olefin is a copolymer. 50 wt% or more (ie, the amount of structural units derived from α, β-unsaturated carboxylic acid is 50 wt% or less in the copolymer). “α, β-unsaturated carboxylic acid polymer” or “carboxylic acid polymer” is a polymer obtained as a monomer from α, β-unsaturated carboxylic acid, wherein the amount of the structural unit derived from α, β-unsaturated carboxylic acid is 90% by weight or more in the polymer. it means.

The exact mechanism by which surface treatment with a composition containing both an olefin-acid copolymer and a carboxylic acid polymer improves the corrosion resistance of the resin-coated metal sheet is unclear, but both are compact by combining with an oxazoline group-containing copolymer. It can be presumed that the resin film was formed and the permeation of water and oxygen was effectively suppressed. The present invention is not limited to this estimation.

Olefin-acid copolymers used in the present invention can be prepared by copolymerizing olefins with α, β-unsaturated carboxylic acids in a known manner and are also commercially available. In the present invention, one or more olefin-acid copolymers can be used.

The olefin which can be used for manufacture of an olefin acid copolymer is not specifically limited. Ethylene and propylene are preferred, and ethylene is more preferred. As the olefin-acid copolymer, both olefin structural units derived from one kind of olefins or those derived from two or more kinds of olefins can be used.

In addition, the α, β-unsaturated carboxylic acid that can be used in the preparation of the olefin-acid copolymer is not particularly limited. Examples of α, β-unsaturated carboxylic acids include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and isocrotonic acid; And dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. Among these α, β-unsaturated carboxylic acids, acrylic acid is preferable. As the olefin-acid copolymer, a copolymer having an α, β-unsaturated carboxylic acid structural unit derived from only one α, β-unsaturated carboxylic acid, and an α, β-derived from two or more α, β-unsaturated carboxylic acids All copolymers with unsaturated carboxylic acid structural units can be used.

The olefin-acid copolymer used in the present invention may have a structural unit derived from another monomer as long as it does not adversely affect the corrosion resistance as an effect of the present invention. In the olefin-acid copolymer, the amount of structural units derived from other monomers is preferably 10% by weight or less, more preferably 5% by weight or less. Most preferred olefin-acid copolymers consist only of olefins and α, β-unsaturated carboxylic acids. Preferred olefin-acid copolymers include ethylene-acrylic acid copolymers.

The α, β-unsaturated carboxylic acid in the olefin-acid copolymer is used to improve the adhesion between the resin film and the metal sheet and to secure the amount of carboxyl groups that act as a reactor for crosslinking. The amount of α, β-unsaturated carboxylic acid in the copolymer is preferably at least 5% by weight, more preferably at least 10% by weight. However, when the α, β-unsaturated carboxylic acid is excessive, since corrosion resistance and alkali resistance may be lowered, the amount is preferably 30% by weight or less, more preferably 25% by weight or less.

The weight-average molecular weight (Mw) of the olefin-acid copolymer used in the present invention is in terms of polystyrene, preferably 1,000 to 100,000, more preferably 3,000 to 70,000, even more preferably 5,000 to 30,000. Mw can be measured by GPC using polystyrene as a standard.

As the carboxylic acid polymer, any of the copolymers obtained by copolymerizing one or more kinds of homopolymers or copolymers of α, β-unsaturated carboxylic acids or other monomers can be used. These carboxylic acid polymers can be produced by a known method and are also commercially available. In the present invention, one or more carboxylic acid polymers can be used.

As the α, β-unsaturated carboxylic acid that can be used for the preparation of the carboxylic acid polymer, any α, β-unsaturated carboxylic acid exemplified as those which can be used for the synthesis of the olefin-acid copolymer can be used. Among these, acrylic acid and maleic acid are preferable, and maleic acid is more preferable.

The carboxylic acid polymer may contain structural units derived from monomers other than α, β-unsaturated carboxylic acids. The amount of the structural unit derived from the other monomer is 10% by weight or less, preferably 5% by weight or less in the polymer. More preferred are carboxylic acid polymers composed exclusively of α, β-unsaturated carboxylic acids.

Preferred carboxylic acid polymers include, for example, polyacrylic acid, polymethacrylic acid, acrylic acid-maleic acid copolymers and polymaleic acid. Among these, polymaleic acid is more preferable from a viewpoint of film adhesiveness, resin film adhesiveness, and corrosion resistance. The exact mechanism by which the polymaleic acid is used to improve the corrosion resistance of the resin-coated metal sheet is unclear, but the amount of carboxyl groups is high, and thus the adhesion between the resin film and the metal sheet is improved, and therefore the corrosion resistance is also considered to be improved. The present invention is not limited to this estimation.

The polystyrene equivalent Mw of the carboxylic acid polymer used in the present invention is preferably 500 to 30,000, more preferably 800 to 10,000, even more preferably 900 to 3,000, most preferably 1,000 to 2,000. Mw can be measured by GPC using polystyrene as a standard.

The ratio of olefin-acid copolymer and carboxylic acid polymer in the surface treatment composition is from 1,000: 1 to 10: 1, preferably from 200: 1 to 20: 1, more preferably from 100: 1 to 10: 3. If the amount of the carboxylic acid polymer is too low, the effect of using the olefin-acid copolymer in combination with the carboxylic acid polymer is not sufficiently exhibited. On the other hand, when the amount of the carboxylic acid polymer is excessive, phase separation occurs between the olefin-acid copolymer and the carboxylic acid polymer, so that a uniform resin film cannot be formed and there is a fear that the alkali resistance is lowered.

The resin component also includes an oxazoline group-containing copolymer. Since the oxazoline group of the oxazoline group-containing copolymer crosslinks with the carboxyl groups of the olefin-acid copolymer and the carboxylic acid polymer, the resin is crosslinked to form a dense network. As a result, the strength of the film is improved.

As the oxazoline group-containing copolymer, "EPOCROS" of NIPPON SHOKUBAI CO., LTD., Whose main chain is styrene-acrylic, is preferable. Particular preference is given to the emulsion-type "Epocross®" series, including grades K-2010E (Tg: -50 ° C), K-2020E (Tg: 0 ° C) and K-2030E (Tg: 50 ° C). do. In order to obtain a hard film, epochross K-2030E is most preferable. These "Epocross®" series have the advantage that the resulting surface treatment composition has a long potlife because the functional groups are blocked and the crosslinking reaction hardly occurs.

In order to improve the hardness of the resin film, the amount of the oxazoline group-containing copolymer is preferably 1 to 9 parts by weight based on 100 parts by weight of the total amount of the olepin-acid copolymer and the carboxylic acid polymer. If the amount of oxazoline group-containing copolymer is less than 1 part by weight, the strength of the film cannot be sufficiently improved. The lower limit is more preferably 2 parts by weight, even more preferably 3 parts by weight. On the other hand, the amount of oxazoline group-containing copolymer is preferably not more than 9 parts by weight, which not only improves brittleness and corrosion resistance, but also reduces coating properties as the carboxyl groups remaining in the resin decrease as a result of sufficient crosslinking of the resin. It is because (adhesiveness in an upper coating) may fall. The upper limit is more preferably 6 parts by weight, even more preferably 5 parts by weight.

As above, the resin component includes an olefin-acid copolymer, a carboxylic acid polymer and an oxazoline group-containing copolymer. When the total amount of the resin component and the colloidal silica described hereafter is 100 parts by weight, the amount of the resin component is preferably 70 to 90 parts by weight, and the amount of the colloidal silica is preferably 10 to 30 parts by weight. In order to improve the hardness of the film, it is effective to use a large amount of colloidal silica, which is an inorganic material and a hard rust preventive pigment of colloidal nano size. If the amount of colloidal silica is too large, the amount of the resin component in the film is reduced, thus degrading the film forming property and making the film brittle. As a result, not only peeling of the film occurs but also undesirably lowers the corrosion resistance and the coating property. On the other hand, if the amount of colloidal silica is too small, the film has poor hardness and exhibits less rust preventing effect, thus lowering the corrosion resistance. When the amount of the resin component and the colloidal silica is within the above range, a resin film having a well balanced hardness and odor, good corrosion resistance and good coating property of the film can be obtained.

The amount of the resin component is preferably 75 parts by weight or more based on 100 parts by weight of the total amount of the resin component and the colloidal silica. The upper limit of the resin component is more preferably 85 parts by weight, even more preferably 80 parts by weight.

[Colloidal silica]

When colloidal silica is present in the film, it dissolves and elutes at the film defects under a corrosive environment, and the dissolution and elution of the metal sheet is suppressed by the buffer effect of pH and the passivation film forming effect, thereby improving the corrosion resistance. The dispersion state in the film depends on the surface area (particle diameter) of the colloidal silica and has a great influence on the mechanical properties such as the hardness and the brittleness of the film. In order to improve the strength of the film by forming a dense film, it is preferable to uniformly disperse the colloidal silica having a small particle diameter of the film. In this respect, the surface area average particle diameter of the colloidal silica is preferably 4 to 20 nm. When the surface area average particle diameter is larger than 20 nm, the surface area itself decreases, and dispersibility tends to decrease. Thus, a dense film cannot be formed, whereby the film has poor strength, and the corrosion improving effect can be reduced. On the other hand, if the surface area average particle diameter is less than 4 nm, the storage stability of the surface treatment composition may decrease, and gelation may occur. The surface area average particle diameter of the colloidal silica is more preferably 4 to 6 nm. The surface area average particle diameter may be measured by the Sears method in the case of about 1 to 10 nm, but the surface area average particle diameter may be measured by the BET method in the case of about 10 to 100 nm.

Colloidal silica is commercially available. For example, "SNOWTEX® XS" from NISSAN CHEMICAL INDUSTRIES, LTD. Can be used as colloidal silica with a surface area average particle diameter of 4-6 nm. As colloidal silica having a surface area average particle diameter of 10 to 20 nm, "Snotex® 40", "Snotex® N", "Snotex® SS" of Nissan Chemical Industries Limited and "Snotex® O", "ADERIGHT® AT-30" and "Aderite® AT-30A" from ADEKA CORPORATION, etc. may be used. . When the surface treatment composition used to form the resin film is an aqueous composition, it is preferable to select the type of colloidal silica according to the pH of the surface treatment composition in order to disperse the colloidal silica well.

[Glycidyl Group-Containing Silane Coupling Agent]

The surface treatment composition of the present invention may further comprise a glycidyl group-containing silane coupling agent. When glycidyl group-containing silane coupling agents are used, the adhesion between the metal and the resin film is improved, and thus the corrosion resistance is also improved. It also has the effect of improving the bonding strength between the resin component and the colloidal silica, and the strength of the film is improved. In particular, glycidyl group-containing silane coupling agents have a high reactivity and have a great effect of improving corrosion resistance or alkali resistance.

Examples of glycidyl group-containing silane coupling agents include γ-glycidoxypropylmethyldietoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxymethyldimethoxysilane and (beta)-(3, 4- epoxycyclohexyl) ethyl trimethoxysilane is mentioned.

It is preferable that the quantity of the silane coupling agent in a surface treatment composition is 0.1-10 weight part with respect to 100 weight part of total amounts of a resin component and colloidal silica. When the amount is less than 0.1 part by weight, the strength and corrosion resistance of the film may be insufficient due to the poor adhesion between the metal sheet and the resin film as well as the bonding force between the resin component and the colloidal silica. Even when the amount exceeds 10 parts by weight, the effect of improving the adhesion between the metal sheet and the resin film is saturated and the functional groups in the resin are reduced, so that the coating property can be lowered. In addition, the silane coupling agent causes a hydrolytic condensation reaction, lowers the stability of the surface treatment composition, and thus gelation and precipitation of colloidal silica may occur. The amount of the silane coupling agent is more preferably 3 to 9 parts by weight, even more preferably 5 to 7 parts by weight.

[Metavana Date]

The surface treatment composition of the present invention may further comprise metavanadate. Metavanadate also inhibits dissolution and elution of the metal sheet by eluting metavanadate, similar to colloidal silica, thereby improving corrosion resistance. Metavanadate exhibits the effect of suppressing the hydrolytic condensation reaction of the silane coupling agent in the surface treatment composition. As a result, the adhesion with the resin film and the bonding force between the resin component and the colloidal silica are improved, and thus the resulting film has a dense and improved strength. In order to effectively exert these effects, metavanadate may be used in an amount of 0.5 to 6 parts by weight based on 100 parts by weight of the total amount of the resin component and colloidal silica. If the amount is less than 0.5 parts by weight, the above effect is not sufficiently developed. However, even when metavanadate is added in excess of 6 parts by weight, the effect is saturated and the stability of the surface treatment composition is also lowered. The amount of metavanadate is preferably 1 to 5 parts by weight, more preferably 3 to 4 parts by weight. The amount of metavanadate is preferably an amount relative to element V.

Examples of metavanadate include ammonium metavanadate (NH ₄ VO ₃ ), sodium metavanadate (NaVO ₃ ) and potassium metavanadate (KVO ₃ ), which metavanadate may be used alone or in combination have. These metavanadates are commercially available and can be obtained easily.

[Carbodiimide Group-containing Compound]

The surface treatment composition of the present invention may further comprise a carbodiimide group-containing compound. Carbodiimide groups react with carboxyl groups in olefin-acid copolymers and carboxylic acid polymers. Therefore, when a carbodiimide group-containing compound is used, alkali resistance can be improved by reducing the amount of carboxyl groups in the resin film. In the present invention, carbodiimide group-containing compounds may be used alone or in combination.

Carbodiimide group-containing compounds are isocyanates such as hexamethylenediisocyanate (HDI), xyylene diisocyanate (XDI), hydrated xyylene diisocyanate (HXDI), 4 , 4-Diphenylmethane diisocyanate (MDI) or tolylene diisocyanate (TDI) can be prepared by heating in the presence of a carbodiimidation catalyst, and also modified by aqueous (water soluble, Water-soluble or water-dispersible) compounds. When the surface treatment composition is an aqueous composition, an aqueous carbodiimide group-containing compound is preferred. Also preferred are compounds containing a plurality of carbodiimide groups in the molecule. When a compound has a some carbodiimide group in a molecule | numerator, corrosion resistance can be improved further by the crosslinking reaction with the carboxyl group in a resin component.

Examples of commercially available polycarbodiimide compounds include N, N-dicyclohexylcarbodiimide, N, N-diisopropylcarbodiimide, and Nisshinbo Industries, Inc. "CARBODILITE®" series as polycarbodiimide (a polymer having a plurality of carbodiimide groups in a molecule) are included. Examples of grades of "Carbolite®" are preferably water-soluble "SV-02", "V-02", "SV-02-L2" and "V-04", and the emulsion type "E- 01 "and" E-02 ".

The amount of carbodiimide group-containing compound is set according to the amount of olefin-acid copolymer and carboxylic acid polymer crosslinked therewith. When the total amount of the olefin-acid copolymer and the carboxylic acid polymer is 100 parts by weight, with respect to 100 parts by weight of the total amount of the olefin-acid copolymer and the carboxylic acid polymer, preferably 0.3 parts by weight or more, more preferably 0.5 parts by weight or more, and more More preferably, it is 8 weight part or more. On the other hand, when the amount of carbodiimide group-containing compound is excessive, the effect of using the olefin-acid copolymer in combination with the carboxylic acid polymer can be reduced. If the aqueous carbodiimide group-containing compound is used excessively in the surface treatment composition, it may adversely affect water resistance and corrosion resistance. In this respect, the amount of the carbodiimide group-containing compound is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, even more preferably based on 100 parts by weight of the total amount of the olefin-acid copolymer and the carboxylic acid polymer. It is 16 weight part or less.

The surface treatment composition of the present invention includes a wax, a crosslinking agent, a diluent, an anti-skinning agent, a surfactant, an emulsifier, a dispersant, a leveling agent, an antifoaming agent, and a range in which the effects of the present invention are not impaired. Penetrants, auxiliary film-forming agents, dyes, pigments, thickeners and lubricants.

The surface treatment composition of the present invention may be a solvent-based composition or an aqueous composition that can be applied to the surface of a metal sheet, and is preferably an aqueous composition because of environmental problems. The surface treatment composition may be organic solvent (for solvent-based compositions) or water, preferably deionized water (for aqueous compositions), olefin-acid copolymers, carboxylic acid polymers, colloidal silica, silane coupling agents, metavanadate, oxa A sleepy group-containing copolymer, and a carbodiimide group-containing compound or other component, if necessary, may be prepared by mixing the respective amounts, followed by stirring.

The surface treatment composition is prepared by adding a portion of a silane coupling agent and a carbodiimide group-containing compound to an emulsion of an olefin-acid copolymer and a carboxylic acid polymer, thereby preparing a mixture, to which colloidal silica, residual glycidyl group-containing silane is added. It is preferably prepared by adding the phosphorus coupling agent, metavanadate and oxazoline group-containing copolymer in order. Gelation may occur when the oxazoline group-containing copolymer is added directly to the olefin-acid copolymer and the carboxylic acid polymer and then mixed. In addition, when metavanadate is added before adding the silane coupling agent, the reaction of the silane coupling agent can be suppressed. As described above, the silane coupling agent is preferably added two or more times for the following reasons. The silane coupling agent added first contributes to the purification of the emulsion particles and the resulting densification of the resin film, and the silane coupling agent added subsequently contributes to securing adhesion with the metal sheet and improving film properties.

The components can be heated upon stirring. When the olefin-acid copolymer is emulsified in the presence of a carboxylic acid polymer, heating is preferred. However, it cannot be heated after mixing an oxazoline group containing copolymer. This is because the surface treatment composition is prevented from gelling by the reaction of the oxazoline group-containing copolymer with the olefin-acid copolymer and the carboxylic acid polymer.

When producing an aqueous surface treatment composition, it is preferable that the olefin-acid copolymer as a main component of the resin component is emulsified. The olefin-acid copolymer can be emulsified using an emulsifier or by neutralizing the carboxyl groups in the copolymer. Using an emulsifier, the average particle diameter of the aqueous emulsion of the olefin-acid copolymer can be reduced, and also the density of the resin film can be improved.

It is preferable to emulsify by neutralizing the carboxyl groups in the olefin-acid copolymer for the following reasons. That is, when the olefin-acid copolymer is emulsified by neutralizing a carboxyl group, the amount of emulsifier can be reduced, or there is no need to use an emulsifier, thus reducing or eliminating the adverse effect of the emulsifier on water resistance and corrosion resistance. . When the carboxyl groups in the olefin-acid copolymer are neutralized, the base is preferably used in an amount of about 0.5 to 0.95 equivalents, more preferably about 0.6 to 0.8 equivalents. If the degree of neutralization is too small, the emulsification is not sufficiently improved. On the other hand, if the degree of neutralization is too high, the amount of carboxyl groups reacted with the oxazoline group-containing copolymer may decrease and thus adversely affect the corrosion resistance, and the viscosity of the composition comprising the olefin-acid copolymer is excessively excessive. Increases.

Examples of the base for neutralization include strong bases composed of a group consisting of hydroxides of alkali metals and alkaline earth metals (eg, NaOH, KOH, Ca (OH) ₂ , preferably NaOH); ammonia; And primary, secondary and tertiary amines (preferably triethylamine). If a strong base such as NaOH is used, the emulsification is improved, but if the amount of the strong base is too large, the corrosion resistance of the resin film may be lowered. On the other hand, an amine having a low boiling point (preferably, an amine having a boiling point of 100 ° C. or lower under atmospheric pressure) does not significantly reduce the corrosion resistance of the resin film. For this reason, when the resin film is formed by applying heat-drying the surface treatment composition and then drying, low-boiling amine may be considered to be volatilized. However, since amine has a small effect of improving emulsification, it is preferable to neutralize the strong base and the amine in combination. The best combination is a combination of NaOH and triethylamine. When using a combination of a strong base and an amine, it is preferable to use about 0.01 to 0.3 equivalents of the strong base and about 0.4 to 0.8 equivalents of the amine relative to the amount of the carboxyl group of the olefin-acid copolymer.

When using an aqueous surface treatment composition, a small amount of organic solvent can be used to improve the wettability into the metal sheet by reducing the interfacial tension. Examples of organic solvents include methanol, ethanol, isopropanol, butanol class, hexanol, 2-ethylhexanol, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol and propylene glycol.

Solid content of a surface treatment composition is not specifically limited, It can adjust according to the application method of the surface treatment composition on a metal sheet. The solid content of the surface treatment composition is generally about 5 to 20% by weight, and preferably about 10 to 20 when applied by the spray ringer method (the coating method of spraying the surface treatment composition onto the surface of the metal sheet and then squeezing it into a roll). 18 wt%.

The metal sheet used in the present invention is not particularly limited. Examples of the metal sheet include an unplated cold rolled steel sheet, a hot dip galvanized steel sheet (GI), a galvannealed steel sheet (GA), and an electrogalvanized steel sheet (EG). ), Aluminum plate and titanium plate. Among these metal sheets, it is preferable to apply the present invention to a hot dip galvanized steel sheet (GI) or an alloy galvanized steel sheet (GA) to which no chromate treatment is applied.

In the present invention, there is no particular limitation on the method of forming the resin film on the metal sheet and the conditions thereof. Resin-coated metal sheets can be prepared by applying the surface treatment composition to one or both surfaces of the metal sheet surface using a known coating method and then drying them by heating. Examples of the coating method of the surface treatment composition include a curtain flow coating method, a roll coating method, a spray method, and a spray ringer method. Among them, the spray ringer method is preferable from the viewpoint of cost.

After coating, the surface treatment composition is dried while heating such that the metal sheet attainment temperature falls within 120 to 180 ° C for the following reason. That is, the crosslinking reaction of the resin is promoted by setting to a higher drying temperature to obtain a hard but brittle resin film. Chemical changes in the resin structure as a result of increasing the heating temperature could not be confirmed by FT-IR. However, when heated to a temperature lower than 120 ° C., the formed film has poor strength due to the insufficient film-forming properties and the degree of crosslinking of the film, and thus the film peel resistance is not sufficiently expressed. Heating to temperatures higher than 180 ° C. is undesirable because the film becomes too hard and also causes cracking of the film surface and leads to lower film peeling resistance and lower corrosion resistance, making it more brittle.

The coating weight of the resin film in the resin-coated metal sheet is preferably 0.1 to 1 g / m ² , more preferably 0.3 to 0.6 g / m ² in dry weight. If the coating weight is too small, its hardness is close to the original one, but it is difficult to coat the surface of the metal sheet, and the film peeling resistance by roll forming may be lowered. On the other hand, increasing the coating weight is undesirable because the hardness of the film is reduced by the influence of the repulsive force of the resin component and the amount of peeled film increases during roll forming.

[Example]

Hereinafter, the present invention will be further described by way of examples. It is to be understood that the invention is not limited to the following examples, and that various design changes made in accordance with the spirit herein before and after have also been included within the technical scope of the invention.

The characteristic evaluation method used in the Example is as follows.

[Sword Locker Longitude]

Sword rocker hardness was measured by the method described previously.

[Entry depth of indenter (μm) in nanoscratch test]

The entry depth of the indenter in the nanoscratch test was measured by the method described above.

[Surface Sliding Test]

The surface sliding test was conducted as an indirect evaluation test of roll formability. As shown in Fig. 5, a resin-coated metal sheet cut to 40 mm x 300 mm was installed perpendicular to the tension tester, and the SUS die of the protrusion having the tip diameter R of 1 mm was placed on the surface of the metal sheet. After contacting (linear contact), the flat die was contacted with the rear surface of the metal sheet. The metal sheet was pulled upward while a load of 1960 N was applied horizontally to the die with the protrusions. The metal sheet was reset every time it was pulled and pulled a total of 5 times. The length including the protrusion (sliding part) was adjusted to 150 mm and the upper and lower ends were in contact with the protrusion. The sliding speed to adjust was 300 mm / min. After the portions (non-sliding portions) and the sliding portions not in contact with the protrusions were punched to a size of 50 mm in diameter, the amount of Si in the film was measured by fluorescence X-ray analysis. The film residual ratio (%) was calculated by dividing the Si amount of the sliding portion by the Si amount of the non-sliding portion.

A. Film Retention Rate Above 80% and Below 100%

B. Film Retention Rate Above 60% and Below 80%

C. Film Retention Rate> 40% and Less Than 60%

D. Film Retention Rate Below 40%

[Sheet corrosion resistance]

The salt spray test was carried out according to JIS Z2371, and the time until the white rust incidence rate (the area where 100 x white rust occurred / total area of the test substance) became 5% was measured. If the corrosion resistance of the sheet is 120 hours or more, the sheet is suitable for practical use.

Corrosion Resistance in JASO Cycle Test

The JASO cycle test was done in accordance with JIS H8502. One cycle consists of a salt spray step (2 hours at a temperature of 35 ° C.), a drying step (4 hours at a temperature of 35 ° C. and a humidity of 30% or less) and a wet step (2 hours at a temperature of 50 ° C. and a humidity of 95% or more). (Each step includes a transition time). After 15 cycles, the incidence of white rust was evaluated according to the following criteria.

A: less than 5% incidence of white rust

B: White rust incidence 5% or more but less than 10%

C: White rust incidence 10% or more but less than 20%

D: 20% or more occurrence of white rust

[Coating Property]

In the resin-coated metal sheet, an acrylic coating material (top coating) was applied by a bar-coating method to obtain a film having a thickness of 20 μm after drying, followed by 20 minutes at 160 ° C. Heating and further post-coating. The test substance was immersed in boiling water for 1 hour, taken out, and left for 1 hour. Vertical and horizontal cut lines were formed with a cut knife at intervals of about 1 mm to form 100 square sections, and a tape peel test was performed. Film adhesiveness was evaluated by the number of remaining square sections of the film.

A: 100% coating film residual rate

B: coating film residual rate less than 100% 90% or more

C: coating film residual rate less than 90% 80% or more

D: less than 80% coating film residual ratio

Experimental Example 1

Ethylene-acrylic acid copolymer ("PRIMACOL® 5990I" from Dow Chemical Co., acrylic acid in a 1.0L autoclave equipped with stirrer, thermometer and temperature controller) Structural units derived from: 20 wt%, weight-average molecular weight (Mw): 20,000, melt index: 1,300, acid value: 150) 200.0 g, aqueous polymaleic acid solution (NOFOL, manufactured by NOF Corporation) PMA-50W ", Mw: 8.0 g of about 1,100 (polystyrene equivalent), 50 weight%), 35.5 g of triethylamine (0.63 equivalent with respect to the carboxyl group of an ethylene-acrylic acid copolymer), 6.9 g (48% NaOH aqueous solution) 0.15 equivalents to the carboxyl group of the ethylene-acrylic acid copolymer, 3.5 g of tall oil fatty acid (HARIMA CHEMICALS, INC. "HARTALL FA3") and 792.6 g of ion-exchanged water Sealed, and stirred at 150 ° C. and 5 atmospheres under high speed for 3 hours. The. After cooling to 30 ° C, glycidyl group-containing silane coupling agent (Momentive Performance Materials (formerly known as GE Toshiba Silicones) "TSL8350", γ- Glycidoxypropyltrimethoxysilane) 10.4 g, carbodiimide group-containing compound (Nicashinbo Industries, Inc. " Carbodiite® SV-02 ", polycarbodiimide, Mw: 2,700, 40 wt% solids) and 32.8 g of ion-exchanged water were added, followed by stirring for 10 minutes to prepare a first emulsion (20.3 wt% solids, measured according to JIS K6833).

The first emulsion and colloidal silica (Nissan Chemicals, Inc. "Snotex® XS", surface area average particle diameter (catalog value): 4-6 nm) are mixed well in the respective varying amounts shown in Table 1 Glycidyl group-containing silane coupling agent (Shin-Etsu Silicone Co., Ltd. "KBM403", γ-glycidoxypropyltriethoxysilane) Parts by weight, 3 parts by weight of sodium metavanadate ("Metavanadate Soda", manufactured by Shinko Chemical Co., Ltd.), and an oxazoline group-containing copolymer (Nippon Shokubai Company Limited) "Epocross® K-2030E", 40 weight percent solids) was added alternately in respective amounts relative to 100 weight parts of the first emulsion and colloidal silica to prepare a first surface treatment composition. The amount of the resin component in Table 1 corresponds to the total amount of the resin (solid content) in the first emulsion and the oxazoline group-containing copolymer. The oxazoline group-containing copolymer was added in an amount of 5 parts by weight based on 100 parts by weight of the total amount of the ethylene-acrylic acid copolymer and the polymaleic acid.

Using a alkali-degreased galvanized steel sheet (Zn coating weight 45 g / m ² ) as the metal sheet, the first surface treatment composition was bar-coated using a bar-coating (third bar) method against the surface of the steel sheet. Thereafter, drying was performed while heating at a sheet temperature of 150 ° C. for about 12 seconds to prepare a resin-coated metal sheet having a resin film coating weight of 0.5 g / m ² .

Resin component
(Parts by weight) Silica
(Parts by weight) Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter
(μm) burglar:
surface
sliding
The test result Corrosion Resistance of Sheet
(hr) cycle
exam
Corrosion resistance Coating Embodiment 1 of the present invention 90 10 35 0.22 B 120 B A Embodiment 2 of the present invention 85 15 37 0.17 A 144 B A Embodiment 3 of the present invention 80 20 40 0.15 A 168 A A Embodiment 4 of the present invention 75 25 41 0.15 A 168 A B Embodiment 5 of the present invention 70 30 43 0.22 B 168 A B Comparative Example 1 65 35 45 0.31 C 120 B B Comparative Example 2 60 40 47 0.40 C 96 D C Comparative Example 3 95 5 33 0.26 C 96 C A

Experimental Example 2

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1, but with respect to 100 parts by weight (solids) of the ethylene-acrylic acid copolymer and the polymaleic acid in the first emulsion, the amount of the oxazoline group-containing copolymer was Modified as shown in Table 2, the ratio of resin component to colloidal silica was fixed at 80 parts by weight / 20 parts by weight. The evaluation results are shown in Table 2.

Oxazoline group-containing copolymer
(Parts by weight) Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter
(μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Coating Embodiment 6 of the present invention One 37 0.25 B 144 B A Example 7 of the present invention 3 40 0.21 A 144 A A Example 8 of the present invention 5 40 0.15 A 168 A A Embodiment 9 of the present invention 7 41 0.16 A 168 A A Embodiment 10 of the present invention 9 41 0.18 A 168 A B Comparative Example 4 0.5 33 0.30 C 120 C A Comparative Example 5 0 31 0.40 D 120 C A Comparative Example 6 11 34 0.21 C 144 B C Comparative Example 7 15 31 0.26 C 144 B D

Experimental Example 3

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1, except that the ratio of the resin component to the colloidal silica was fixed at 80 parts by weight / 20 parts by weight, and the surface area average particle diameter (nm) of the colloidal silica was shown in Table 3. Modifications were made as shown. The colloidal silica of Example 12 of the present invention is "Snotex® 20" of Nissan Chemical Industries Limited, the colloidal silica of Comparative Example 8 is "Snotex® XL" of the same company product, Colloidal silica of Comparative Example 9 is "Snotex® ZL" manufactured by the same company.

Silica
Surface Area Average Particle Diameter
(nm) Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter
(μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Coating Embodiment 11 of the present invention 4 to 6 40 0.15 A 168 A A Example 12 of the present invention 10-20 38 0.22 B 144 B A Comparative Example 8 40-60 34 0.31 C 120 C B Comparative Example 9 70-100 30 0.38 C 96 D B

Experimental Example 4

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1, except that the ratio of the resin component to the colloidal silica was fixed at 80 parts by weight / 20 parts by weight, and based on 100 parts by weight of the resin component and the colloidal silica (solid content). The amount of glycidyl group-containing silane coupling agent ("KBM403" from Shin-Etsu Silicone Co., Ltd. product) added later was changed as shown in Table 4. The evaluation results are shown in Table 4.

Glycidyl groups
-Containing silane
Coupling agent
(Parts by weight) Hardness:
Sword
Rocker hardness Odority:
Intenter
Entry depth
(μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Coating Embodiment 13 of the present invention 0.5 36 0.23 B 144 B A Example 14 of the present invention One 38 0.20 B 144 B A Example 15 of the present invention 3 39 0.18 A 144 A A Embodiment 16 of the present invention 5 40 0.16 A 168 A A Example 17 of the present invention 7 40 0.15 A 168 A A Example 18 of the invention 9 39 0.17 A 168 A B Example 19 of the present invention 10 38 0.24 B 144 A B Comparative Example 10 15 34 0.30 C 120 C C Comparative Example 11 20 30 0.36 C 96 D C Comparative Example 12 25 Gelation Comparative Example 13 0 34 0.31 C 120 C A

Experimental Example 5

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1, except that the ratio of the resin component to the colloidal silica was fixed at 80 parts by weight / 20 parts by weight, and based on 100 parts by weight of the resin component and the colloidal silica (solid content). The type and amount of metavanadate were changed as shown in Table 5. The evaluation results are shown in Table 5.

Metavanadate Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter (μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Kinds Parts by weight Example 20 of the present invention a 0.5 37 0.29 B 120 B Example 21 of the present invention a One 38 0.23 B 144 B Example 22 of the present invention a 2 40 0.18 A 144 B Example 23 of the present invention a 3 40 0.15 A 168 A Embodiment 24 of the present invention b 3 40 0.15 A 168 A Embodiment 25 of the present invention c 3 40 0.15 A 168 A Embodiment 26 of the present invention a 4 41 0.16 A 168 A Embodiment 27 of the present invention a 6 39 0.22 B 144 B Comparative Example 14 a 7 37 0.30 C 144 B Comparative Example 15 a 0.3 34 0.31 C 120 C

a: sodium metavanadate

b: ammonium metavanadate

c: potassium metavanadate

All of these are manufactured by Cinco Chemical Company Limited.

Experimental Example 6

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1, wherein the ratio of the resin component to colloidal silica was fixed at 80 parts by weight / 20 parts by weight, and the drying temperature (metal sheet attainment temperature) after applying the surface treatment composition was The change was made as shown in Table 6. The evaluation results are shown in Table 6.

Drying temperature
(℃) Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter (μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Coating Embodiment 28 of the present invention 120 37 0.23 B 144 B A Embodiment 29 of the present invention 140 39 0.17 A 168 A A Example 30 of the present invention 150 40 0.15 A 168 A A Example 31 of the present invention 160 41 0.19 A 168 A A Example 32 of the present invention 180 42 0.21 A 168 A B Comparative Example 16 200 45 0.35 C 144 B C Comparative Example 17 100 34 0.27 C 120 B A Comparative Example 18 80 33 0.30 C 120 B A

Experimental Example 7

A resin-coated metal sheet was prepared in the same manner as in Experimental Example 1 except that the ratio of resin component to colloidal silica was fixed at 80 parts by weight / 20 parts by weight, and the resin coating weight was changed as shown in Table 7.

Film
Coating weight
(g / m ² ) Hardness:
Sword
Rocker hardness Odority:
Entry depth of indenter (μm) burglar:
surface
sliding
The test result Of sheet
Corrosion resistance
(hr) cycle
exam
Corrosion resistance Coating Embodiment 33 of the present invention 0.1 42 0.09 B 120 B A Embodiment 34 of the present invention 0.3 41 0.15 A 144 A A Example 35 of the present invention 0.5 40 0.15 A 168 A A Embodiment 36 of the present invention 0.7 38 0.15 A 168 A A Example 37 of the present invention 1.0 36 0.15 B 192 A B Comparative Example 19 0.05 43 0.04 D ^* 96 C D Comparative Example 20 1.2 34 0.15 D 192 A B

* Means that the entire galvanization was peeled off.

As is clear from the results shown in Tables 1 to 7, the resin-coated metal sheet of the embodiment of the present invention has a strong resin film well balanced in hardness and brittleness, and also excellent in corrosion resistance and coating property.

The resin-coated metal sheets of the present invention have a resin film having improved film peel resistance in roll forming, and therefore they can be preferably used in automobiles, home appliances and building materials.

1 is a front view of a seward rocker.

2 is a rear view of the Seward Locker.

3 is a side view of the Seward Rocker.

4 is a front view of the Seward Rocker.

5 is an explanatory diagram of a test method for evaluating the film residual ratio according to the sliding surface.

Claims (8)

A resin-coated metal sheet comprising a resin film made from a surface treatment composition, The surface treatment composition contains (a) a resin component comprising an olefin-α, β-unsaturated carboxylic acid copolymer, an α, β-unsaturated carboxylic acid polymer and an oxazoline group-containing copolymer, and (b) colloidal silica. And based on 100 parts by weight of the total amount of the resin component and colloidal silica, the amount of the resin component is 70 to 90 parts by weight, the amount of the colloidal silica is 10 to 30 parts by weight, A resin-coated metal sheet, wherein the resin film has a Sword rocker hardness of 35 or more and an indenter depth of less than 0.3 μm in a nanoscratch test. delete The method of claim 1, The resin component contains an oxazoline group-containing copolymer in an amount of 1 to 9 parts by weight based on 100 parts by weight of the total amount of the olefin-α, β-unsaturated carboxylic acid copolymer and the α, β-unsaturated carboxylic acid polymer. Resin-coated metal sheet. The method of claim 1, And the colloidal silica has a surface area average particle diameter of 4 to 20 nm. The method of claim 1, A resin-coated metal sheet further comprising a glycidyl group-containing silane coupling agent in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the total amount of the resin component and colloidal silica. The method of claim 1, A resin-coated metal sheet further containing metavanadate in an amount of 0.5 to 6 parts by weight. The method of claim 1, Resin-coated metal sheet, characterized in that the coating weight of the resin film in the resin-coated metal sheet is 0.1 to 1 g / m ² (dry basis). The method according to any one of claims 1 and 3 to 7, The resin film is formed by applying a surface treatment composition to a metal sheet and heating to a sheet temperature of 120 to 180 ° C.

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