JP3993815B2 - Coated metal plate with excellent conductivity, corrosion resistance and formability - Google Patents

Description

【００６２】
結果を表2に示す。本発明の実施例に示される如く、導電性粒子の粒度分布を、粒径分布最頻値で0.05〜1.0μmの範囲内、及び添加量を15〜60容量%に制御することで、良好な溶接性と成形性、耐食性が確保できる。また、個数分布最頻値の含有量を5容量%以上にすること、体積分布最頻値で2〜20μmの範囲内に制御すること、もしくは導電性粒子の最大粒径、膜厚を適正な値に制御することで、さらに良好な溶接性と成形性、耐食性が確保できる。
【００６３】
No.1、10、11、14、27、29の比較例は、本発明例から外れた被覆金属板の例を示した。No.1は導電性粒子量が少なく、導電性が得られない。No.10は導電性粒子量が多すぎ、成形性が低下する。No.11は個数分布最頻値が低く、導電性が低下する。No.14、27、29は個数分布最頻値が大きいため、成形性、耐食性が低下する。
【００６４】
【表２】

【００６５】
(実施例2)
各種の導電性粒子あるいは防錆顔料が混合されている場合、及び樹脂系を変えた場合の条件を表3に示す。導電性粒子、防錆顔料を、ウレタン-エポキシ系樹脂、ポリエステル-メラミン系樹脂、ポリエステル-ウレタン系樹脂、アクリル-ポリエステル系樹脂、ポリエチレンテレフタレート樹脂、高分子ポリエステル樹脂に所定量混合し、金属板上に塗布後、焼付・乾燥した。その他の被覆金属板製造方法は、実施例１と同様である。得られた被覆金属板について、実施例１と同様の条件で、溶接性、成形性、耐食性の評価を実施した。
【００６６】
【表３】

【００６７】
その結果を表4に示す。大きな粒径のステンレス鋼粒子を添加した場合、そのステンレス鋼粒子の含有量が5容量%以下であると、成形性を低下させず、バランスの良い溶接性、成形性、耐食性が得られる。10容量%以上の添加では、加工性がやや低下するようになる。また、防錆顔料が20容量%以下であると、溶接性、成形性を低下させずに、良好な耐食性を得ることができる。また、熱可塑性樹脂を用いることで、良好な溶接性を得ることができる。
【００６８】
No.38〜40、48の比較例は、本発明の範囲を外れた被覆金属板の例を示した。No.39は導電性粒子量が少なすぎ、導電性が得られない。No.38、40は個数分布最頻値が大きすぎ、成形性、耐食性が大きく低下する。No.48は導電性粒子量が多すぎ、成形性が大きく低下する。
【００６９】
【表４】

【００７０】
(実施例3)
粒径分布を制御した導電性粒子あるいはその他の粒子を含有するウレタン-エポキシ系樹脂皮膜を塗布した金属板について、燃料タンク材料としての適性評価を実施した例を表5に示す。端面耐食性を除く実施例１の性能評価項目に加え、下記に示すシーム溶接性、及びタンク内面側を模擬した耐食性試験を実施した。
【００７１】
(5) シーム溶接性
先端R6mm-φ250mmの電極輪を用い、溶接電流11kA、加圧力4.9kN、通電2on-1offで10mのシーム溶接を行った後、JIS-Z-3141に示す試験片を作製し、漏れ試験を実施した。
【００７２】
◎:漏れ無し
○:漏れ無いが、溶接部表面がやや荒れているもの
△:漏れ無いが、溶接部表面に割れ等の欠陥が発生しているもの
×:漏れ発生
(6) 内面耐食性
ガソリンに対する耐食性を評価した。方法は、油圧成型試験機によりフランジ幅20mm、直径50mm、深さ25mmの平底円筒深絞りした試料に、試験液を入れて、シリコンゴム製リングを介してガラスで蓋をした。この試験後の腐食状況を目視観察した。
【００７３】
(試験条件)
試験液:ガソリン+蒸留水10%+ギ酸200ppm
試験期間:40℃で3ヶ月放置
(評価基準)
◎:変化無し
○:白錆発生1%以下
△:赤錆発生5%以下，または白錆発生1〜50%
×:赤錆発生5%超又は白錆顕著
【００７４】
【表５】

【００７５】
その結果を表6に示す。導電性粒子あるいはその他の粒子を適正な粒度分布、含有量に制御した被覆金属板は、良好な溶接性と成形性、耐食性が得られ、燃料タンク素材としても適することが分かった。
【００７６】
N0.54、59、62、67の比較例は、本発明を外れる被覆金属板を示した。No.54、62は、導電性粒子量が少なく溶接性が不良である。No.59、67は、導電性粒子の個数分布最頻値が大きく、成形性、耐食性が悪い。
【００７７】
【表６】

【００７８】
【発明の効果】
以上の結果から、本発明の粒度分布を制御した導電性粒子を含有する被覆金属板は、家電、OA機器、土木・建材、自動車用等の溶接を行う部品、アース性を必要とする部品に幅広くかつ容易に用いることができ、さらに、良好な成形性、耐食性をも確保できるため、さまざまな用途での適用が期待され各種産業分野への寄与が大きい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal plate on which a coating layer containing conductive particles used for home appliances, OA equipment, civil engineering / building materials, automobiles and the like is formed.
[0002]
[Prior art]
Since the coating layer formed on the metal plate uses a resin or the like that does not have conductivity as its binder, it does not have conductivity, cannot be welded, and is difficult to ground. Then, the technique which provides electroconductivity by forming the coating layer containing electroconductive particle on a metal plate, enables welding, and the technique which provides the electroconductivity for taking earth | ground is proposed. .
[0003]
For example, JP-A-9-234820 exemplifies a technique for imparting weldability by applying a resin coating using iron phosphide as conductive particles to a metal plate. Here, the amount of the conductive particles is defined as 20 to 45% by mass, and the weldability is ensured by controlling this amount. It is stated that the average particle size is preferably 20 μm or less for the particle size.
[0004]
Japanese Patent Application Laid-Open No. 7-314601 exemplifies a technique for imparting grounding properties by using Ni-based particles as conductive particles. Here, an average value and a maximum value are defined for the particle diameter of the conductive particles. In the case of flakes, the longest diameter is 100 μm, the average is 15 μm, 11 to 200 parts, and when adding a chain It is described that it is important to add 10 parts or less of a maximum of 44 μm and an average of 2.5 μm in order to ensure conductivity.
[0005]
In addition, Japanese Patent Laid-Open No. 1-60668 defines the ratio between the average particle diameter of metal-based particles and the coating thickness for imparting conductivity, and the average particle diameter is 0.5 to 3 times the film thickness. Describes that electrical conductivity can be secured. Although there is no detailed description of the particle size, examples in which the average particle size is 7.5 to 25 μm are described in the examples.
[0006]
Recently, JP-A-2002-172363 discloses that welding is performed by coating a zinc-based plated steel sheet with a thickness of 2.5 to 8 μm with an organic resin film containing 10 to 70 mass% of ferrosilicon having a particle size of 0.5 to 10 μm. A technique for obtaining a surface-treated steel sheet having excellent properties has been proposed.
[0007]
Each of the above inventions presents sufficient techniques in terms of imparting conductivity to the coating layer, thereby ensuring weldability and grounding properties as the coated metal plate. However, it is insufficient in terms of obtaining stable weldability and grounding properties, as well as achieving both formability and corrosion resistance. This is partly due to the fact that only the concept of average particle size or maximum particle size is used for the particle size, and the particle size distribution is not considered.
[0008]
From the viewpoint of improving corrosion resistance, the addition of a rust-preventing pigment is described in the above-mentioned JP-A-9-234820 and JP-A-2002-172363. Therefore, since conductivity and moldability are reduced, it is necessary to minimize the addition of rust preventive pigments if possible. Japanese Patent Laid-Open No. 2002-172363 describes that a coated steel sheet that is superior in corrosion resistance can be obtained when a zinc alloy plated steel sheet is used as a base plated steel sheet. In some cases, high corrosion resistance and formability can be obtained regardless of the type of steel sheet used as a base.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-234820 [Patent Document 2]
Japanese Patent Laid-Open No. 7-314601 [Patent Document 3]
Japanese Patent Laid-Open No. 1-60668 [Patent Document 4]
JP 2002-172363 A [0010]
[Problems to be solved by the invention]
In order to solve the above-described problems, an object of the present invention is to provide a coated metal plate that is excellent in conductivity (for example, weldability and grounding property), corrosion resistance, and formability.
[0011]
[Means for Solving the Problems]
One of the technical points of the present invention is that regarding the particle size of the conductive particles formed on the metal plate, “average particle size” proposed in JP-A-7-314601 and JP-A-2000-319790 is proposed. It has been found that conductivity, corrosion resistance, and moldability can be achieved by taking into consideration not the “diameter” but the particle size distribution. Another point is that, conventionally, the average particle size is relatively large. For example, as shown in Japanese Patent Laid-Open No. 1-60668, by adding conductive particles having a certain size or more to the coating thickness, In contrast to ensuring the conductivity, it was found that the use of conductive particles having a small particle size stabilizes the conductivity and also has a positive effect on corrosion resistance and moldability. That is.
[0012]
In particular,
(1) In a metal plate in which a coating layer in which the binder component containing conductive particles is an organic resin is formed on at least one side, the mode value of the number distribution of conductive particles is in the range of 0.05 to 1.0 μm in particle size. And a coated metal plate excellent in conductivity, corrosion resistance and formability, characterized in that the total content in the coating layer of conductive particles is 15 to 60% by volume,
(2) ± 0.025 mu m range falling within the particles of the mode of the number distribution of the conductive particles, and wherein the percentage of the total number of the conductive particles is 5% or more (1)
The coated metal plate according to 1.
(3) The mode value in the volume distribution for each particle diameter of the conductive particles is 2 to 20 μm (1) or the coated metal plate according to (2),
(4) The coated metal plate according to any one of (1) to (3), wherein the average thickness of the coating layer is 2 to 20 μm,
(5) The coated metal plate according to any one of (1) to (4), wherein the maximum particle size of the conductive particles is 25 μm or less,
(6) The coated metal plate according to any one of (1) to (5), wherein the conductive particles are ferrosilicon,
(7) The coated metal plate according to any one of (1) to (6), wherein the binder component in the coating layer is mainly composed of a resin containing a urethane bond,
(8) The coated metal plate according to any one of (1) to (7), wherein the binder component in the coating layer is mainly composed of a thermoplastic resin.
(9) The coated metal plate according to any one of (1) to (8), wherein the coating layer contains a rust preventive pigment and / or silica in an amount of 20% by volume or less,
It is.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, it is essential to form a coating layer in which the binder component containing conductive particles is an organic resin on at least one surface of a metal plate. The mode value of the number distribution needs to be 0.05 to 1.0 μm. Although there is a distribution in the particle size, the concept of “average particle size” is simply used in the prior art. This is obtained by simply arithmetically calculating the particle size of each particle. However, the inventors are not a simple average of the particle size, the particle size distribution is important.Especially, which particle size is the most, the conductivity (weldability and grounding) of the entire coated metal plate, corrosion resistance It has been found that it has a great influence on moldability. The particle diameter of the particles is measured, the number of particles having the particle diameter is counted, the distribution of the number for each particle diameter is examined, and the particle diameter (mode) at which the number is the largest is obtained. When the mode value is 0.05 to 1.0 μm, each performance is high and balanced. When examining the number distribution, it is desirable to collect data with a particle size number measurement range of 0.05 μm (0.025 μm before and after the particle size display value). If the particle size that is the mode of the particle size distribution exceeds 1 μm, data may be collected with a particle size range of 0.1 μm. The particle size distribution can be easily examined with a particle size distribution meter in a paint (liquid) state. In the case of the state of the coating film, a secondary electron image of the cross section of the coating film is taken to measure the particle diameter of the particles. If it is not spherical, the major axis is taken as the particle size of the particle. If the particle size distribution is a normal distribution, the average particle size and the mode value referred to in the present invention match, but if the particle size is actually pulverized or dispersed after being in a paint state, More particles with larger diameters remain, tails are formed on the larger particle diameter side, and the two values do not match.
[0014]
When the mode value is smaller than 0.05 μm, the process of making the particles fine becomes long, and the secondary aggregation of the particles increases, which is not practical. Also, the conductivity is lowered. On the other hand, when the mode value is larger than 1.0 μm, the proportion of large particles increases, and the corrosion resistance and moldability deteriorate. Especially preferably, it is 0.05-0.5 micrometer, and electroconductivity, corrosion resistance, and a moldability become especially favorable.
[0015]
The performance is particularly good when the number of particles, which is the mode value of the particle size, is 5% or more of the total number of particles. Desirably, it is 7% or more.
[0016]
One of the features of the present invention is that the particle size of the conductive particles is smaller than that of the conventional invention. Conventionally, by increasing the particle size to a certain extent with respect to the coating film thickness, the coating film is partially broken due to the penetration of the particles through the coating film or by the pressure of the electrode during welding. The general idea is to ensure conductivity by contacting the electrodes. In this case, as the film thickness increases, it is necessary to increase the particle diameter of the particles for ensuring conductivity, and this technique has been effective only with a substantially thin coating thickness. The present invention is based on the idea of ensuring a current-carrying path by containing a relatively large amount of particles having a small particle size in the coating layer. Use a measure called mode to ensure quantity. Thereby, even when the film thickness is increased, the conductivity can be ensured even if the particle diameter is small. Another feature is that the relationship between the particle size and the film thickness is not necessarily specified.
[0017]
The inventors have further found that the mode value in the volume distribution for each particle diameter of the conductive particles is also important. If the mode of the particle size distribution is in the above range, the conductivity, corrosion resistance, and moldability will be good, and moreover, especially when the mode in the volume distribution is in the range of 2 to 20 μm. Performance is improved. This value is obtained by determining the volume of each particle having a particle diameter and determining the ratio of the total volume of the particles having the particle diameter to the volume of the entire particle. The particle size at which this value is the largest is here the mode value in the volume distribution for each particle size. This is an index in which the influence of particles having a large particle size is stronger, and this value increases more remarkably when the number of large particles is large. Even if the mode value of the number distribution is the same, this value increases if there are many distributions on the larger particle size side. When the mode value in the volume distribution is high, the weldability is particularly likely to deteriorate. Here, the weldability indicates that the continuous spotability is deteriorated and that the metal plate of the welded portion is easily cracked. When this mode value is more than 20 μm, the weldability, particularly the continuous spotting property is lowered, and the formability and the corrosion resistance are also lowered. In order to make it less than 2 μm, it is necessary to reduce the size of the particles with considerable effort, which is inferior in economic efficiency, and the conductivity is lowered when the content of the conductive particles is small. It has been stated that continuous weldability is particularly likely to decrease when the mode of the volume distribution is high, and this is presumed to be due to the following reasons. When the mode value in the volume distribution increases, the unevenness of the coating layer increases, and only the convex portions of the coating layer easily come into contact with the electrode for welding, and the current flow becomes unstable. Is easy to get dirty. Further, the shape of the nugget is deteriorated due to local heat generation, and the welding strength becomes unstable. Since hard conductive particles exist in the convex portion, the coating layer is not compressed by the pressure between the electrodes, and energization is ensured by only one of the conductive particles. In the case of such an energization mode, the current is likely to concentrate on one point, and thus heat generation is also likely to be concentrated on that portion. Under the influence of this heat, the metal plate itself tends to crack at the welded portion and in the vicinity thereof. On the other hand, by setting the mode value in the volume distribution to 20 μm or less, the number of particles having a large particle diameter is reduced and the coating layer surface becomes smoother. It is stable and nuggets are easily formed normally. In addition, the absence of large particles results in a state where the coating layer is slightly compressed by the pressure between the electrodes, which makes it easier to ensure current conduction between the conductive particles, thereby improving conductivity. Furthermore, since the current does not concentrate on one point, the phenomenon that the welded part and the metal plate near the welded part break can be prevented.
[0018]
Further, the moldability is also improved as compared with the prior art within the scope of the present invention. This is because the absence of excessively large particles reduces the dropout of particles during molding, and coating cracks during molding often occur near the interface between the particles and the binder component, but are excessively large. This is because the cracks are reduced by the absence of particles. Moreover, since the unevenness | corrugation of the coating-film surface does not become excess, the slidability of the coating-film surface also becomes good, and the external appearance after performing a draw bead test etc. and corrosion resistance also become favorable. The same applies to the drawing.
[0019]
Corrosion resistance is also improved by improving moldability and eliminating part of the coating from falling off or being damaged. In particular, when particles having an antirust effect such as ferrosilicon are used, the corrosion resistance is improved by increasing the surface area of the particles.
[0020]
In the present invention, the particle size distribution of the conductive particles can be changed by a known method such as mechanical pulverization or classification. Conductive particles are mixed in the binder for forming the coating layer after making the particle size distribution a specific range and mixed in the binder layer by a method that does not change the particle size distribution, for example, stirring with little share. You may disperse | distribute on the conditions which particle | grains grind | pulverize after mixing in a binder. In particular, the order is not specified.
[0021]
The mode value of the volume distribution may be measured with a commercially available particle size distribution meter. In the method of obtaining the above particle size distribution from observation of the cross section of the coating layer, the particle is assumed to be a sphere and obtained from the particle size. May be.
[0022]
In the present invention, it is essential that the content of the conductive particles in the coating layer is 15 to 60% by volume. When the content is less than 15% by volume, the conductivity is insufficient. On the other hand, if it is larger than 60% by volume, the moldability is lowered. More desirably, it is 20 to 35% by volume.
[0023]
In the present invention, the film thickness is not essentially limited. However, when the film thickness is in the range of 2 to 20 μm, conductivity, corrosion resistance, and moldability are particularly good, which is desirable. If it is less than 2 μm, the corrosion resistance is lowered, and if it exceeds 20 μm, the economy is inferior, and the moldability and the grounding property may be lowered. The coating layer may be formed of a plurality of layers instead of a single layer. If necessary, other layers may be formed above and below the coating layer according to the present invention. For example, it is conceivable to form a base treatment layer in the lower layer, and a layer for preventing scratches or a layer for imparting other functions may be formed in the upper layer.
[0024]
When the maximum particle size of the conductive particles is 25 μm or less, the moldability is particularly improved, which is desirable. Regardless of the film thickness, if the maximum particle size is larger than this, cracks are likely to occur in the coating layer when it is subjected to molding. In particular, when the film thickness is in the range of 2 to 20 μm, the conductivity, corrosion resistance, and moldability are best when the maximum particle size of the conductive particles is 25 μm or less.
[0025]
In the present invention, a known substance can be used as the conductive particles. For example, Zn, Ni, Fe, Al, Ag, Au, Cu, Mg, Cr, Sn, stainless steel, Si and other metals, alloys and semiconductor particles, iron phosphide, ferrosilicon, ferromanganese and other iron compounds Examples thereof include oxide particles such as NiO and ZnO, and carbon particles such as carbon black, graphite, and carbon nanotube. The shape of the particles is not particularly limited, and may be a lump shape, flake shape, spherical shape, irregular shape, fiber shape, whisker shape, chain shape, or the like.
[0026]
Among these conductive particles, ferrosilicon is particularly preferable. Ferrosilicon has conductivity and has an effect of improving corrosion resistance. Although the mechanism for improving the corrosion resistance has not been fully elucidated, it is presumed that it dissolves when the coating layer becomes an alkaline environment due to corrosion and forms a strong silica coating to suppress corrosion. Therefore, sufficient corrosion resistance can be exhibited without adding another rust preventive pigment for improving the corrosion resistance, and the factors that impede conductivity can be reduced. When the particle size distribution and content are within the range of the present invention, and when the particle size distribution is within the range of the present invention and the film thickness range is within the range of the present invention, the moldability is also very good. is there. Ferrosilicon also has different types of Si content. In particular, ferrosilicon having a Si content of 70% by mass or more is preferable because of its excellent corrosion resistance and moldability.
[0027]
Of course, a plurality of conductive particles may be used in order to improve weldability and conductivity. When all the conductive particles are within the above-mentioned particle size distribution range of the present invention (number distribution mode value 0.05 to 1.0 μm, volume distribution mode value 2 to 20 μm), there is no particular problem. The content of the conductive particles in the coating layer can be appropriately mixed and used within a range of 15 to 60% by volume. However, when the newly added conductive particles are particles having a large particle size, their content is desirably 5% by volume or less in the coating layer. If it exceeds 5% by volume, the non-uniformity of the particle size distribution becomes large and the moldability tends to be lowered.
[0028]
In order to improve the corrosion resistance, one or more rust preventive pigments and / or silica may be added. Their content is desirably 20% by volume or less in the coating layer. Preferably it is 15 volume% or less. If it exceeds 20% by volume, the conductivity and moldability are particularly likely to be lowered.
[0029]
Examples of anti-corrosion pigments include hexavalent Cr salts such as strontium chromate and calcium chromate. If you want to avoid the use of hexavalent Cr compounds as anti-rust pigments, for example, calcium silicate, aluminum silicate, phosphorus A compound that releases at least one of silicate ions, phosphate ions, and vanadate ions, such as magnesium oxide, aluminum phosphate, phosphorus vanadate, and aluminum vanadate, can be used. If fine silica is further added to this, scratch resistance, film adhesion, and corrosion resistance are improved. Examples of the fine silica include fumed silica, colloidal silica, and agglomerated silica. Calcium deposited silica can also be used.
[0030]
In the present invention, the conductive particles are contained in the coating layer or in a form in which a part thereof is buried in the coating layer surface. In addition to the conductive particles, the coating layer contains a binder component for holding the coating layer, and a known technique can be used for the binder component . As the organic resin of the type of server Indah components, urethane resins, epoxy resins, acrylic resins, polyester resins, fluorine resins, silicone resins, polyolefin resins, butyral resins, polyether resins, sulfone resins, polyamide resins, polyimide resins, amino resins Examples thereof include resins such as phenol resins, vinyl chloride resins, polyvinyl alcohol resins and isocyanate resins, copolymer resins thereof, mixtures thereof and composites thereof . Those cured dried at normal temperature, which is cured dried by heat, those cured dried by ultraviolet rays or energy rays such as electron beams may be selected from known techniques like. In addition, a coated metal plate can be produced by laminating films containing these resins as main components.
[0031]
In addition to these resins, various additives such as a wax for imparting lubricity, an antifoaming agent, a leveling agent, and a dispersing agent can be included in the coating layer.
[0032]
Among these, particularly when a resin including a urethane bond is used in the coating layer, the corrosion resistance, the moldability, and the conductivity can be aligned at a high level. This is because the resin with urethane bond is excellent in flexibility, and when deformed by the welding electrode, it is easily deformed to make sure that the conductive particles are in contact with each other. This is considered to be due to the fact that it is easy to prevent cracking and cracking of the coating film during processing and that it is resistant to deterioration because it is a chemically strong bond.
[0033]
Moreover, when a coating layer has a thermoplastic resin as a main component, the coating metal plate excellent in especially weldability is obtained. This is because when pressure is applied by the welding electrode, the plasticity is exerted and the coating layer is compressed, thereby making the contact between the conductive particles stronger and more reliable, and the welding current flows stably. It is estimated to be.
[0034]
A well-known thing can be used as a metal plate, For example, a steel plate, a copper plate, a titanium plate, an aluminum plate etc. can be illustrated. Furthermore, examples of the steel plate include various plated steel plates, stainless steel plates, cold rolled steel plates, hot rolled steel plates and the like. Furthermore, as plated steel sheets, galvanized steel sheets, zinc alloy plated steel sheets, galvanized steel sheets, tin plated steel sheets, tin alloy plated steel sheets, chrome plated steel sheets, chrome alloy plated steel sheets, aluminum plated steel sheets, aluminum alloy plated steel sheets, nickel Plated steel sheet, nickel alloy plated steel sheet, copper plated steel sheet, copper alloy plated steel sheet, iron plated steel sheet, iron alloy plated steel sheet, iron-phosphorus composite plated steel sheet, manganese-based plated steel sheet, lead-based plated steel sheet, or metal constituting the plating or Examples thereof include composite plated steel sheets in which fine particles such as silica are contained in the alloy.
[0035]
In particular, galvanized steel sheets, galvanized steel sheets (for example, electrogalvanized steel sheets, hot dip galvanized steel sheets, galvannealed steel sheets, zinc-nickel alloy plated steel sheets, zinc-aluminum alloy plated steel sheets, zinc-aluminum- When using magnesium alloy plated steel sheets, etc., aluminum-based plated steel sheets, aluminum-based alloy plated steel sheets (primary steel sheets for automobiles with excellent economic efficiency and corrosion resistance, and painted steel sheets that require grounding for home appliances and OA equipment ( For example, when aluminum-silicon-plated steel sheet, aluminum-zinc-silicon alloy-plated steel sheet, etc. are used, zinc alloy-plated steel sheet (for example, zinc-nickel alloy-plated steel sheet) or tin-based alloy plating is applied to highly corrosion-resistant coated steel sheets for building materials. When a steel plate (for example, a tin-zinc alloy plated steel plate) is used, it can be suitably used as a coated steel plate for a fuel tank. In addition, by using an aluminum plate having poor weldability as an original plate, it can also be suitably used as an automotive primer steel plate having excellent weldability.
[0036]
An undercoat layer may be formed on the surface of these metal plates for the purpose of improving the adhesion between the coating layer and the metal plate, improving the corrosion resistance, or improving the conductivity. As the base treatment layer, a known technique can be used. For example, phosphate treatment, trivalent chromic acid treatment, chromate treatment, Zr treatment, Ti treatment, Mn treatment, Ni treatment, Co Examples include system treatment, V treatment, coupling agent (Si, Ti, etc.) treatment, treatment with organic matter, and the like. The base treatment layer does not have to be a single layer, for example, a zinc phosphate treatment layer is formed and a sealing treatment is performed thereon, and a plurality of treatments such as a chromate treatment is performed after preconditioning with an acidic Ni-containing liquid. May be combined.
[0037]
The metal plate surface can be treated by a known method before forming the base treatment layer or before forming the coating layer when the base treatment layer is not formed. For example, treatments such as degreasing with water, hot water or a degreasing solution, etching with acid or alkali, mechanical grinding with a brush or the like can be performed.
[0038]
The method for producing the coated metal plate of the present invention can be performed by a known method. The coated steel sheet containing conductive particles can be manufactured, for example, by manufacturing a paint in which conductive particles are mixed with a binder component and applying the paint. Depending on the binder component and the contained components, the film can be formed by a known method such as volatilization of a solvent or the like with heat, curing, or curing with an energy ray, if necessary. The coating method can be a known method, and examples thereof include a roll coater, roller coating, brush coating, curtain coater, die coater, slide coater, electrostatic coating, spray coating, dip coating, and air knife coating. . The form of the paint is not particularly limited, such as powder, solid, solvent-based, and water-based. It is also possible to melt the solid paint by applying heat and coat it while extruding it with a die.
[0039]
Alternatively, the coated metal plate can also be produced by kneading conductive particles in advance in the film layer and laminating the film. For laminating, an adhesive may be used, or the film may be heat-melted and directly laminated on a metal plate.
[0040]
The coating layer in the present invention may be formed on at least one side of the metal, but may be formed on both sides. When it is formed on one side, some treatment layer or coating layer may be formed on the other side, or it may be a metal surface.
[0041]
【Example】
The present invention will be described with reference to examples.
[0042]
First, various evaluation tests are described.
[0043]
(1) Spot weldability evaluation Using a 5 mm-R40 Cr-Cu electrode with a tip diameter of 5 mm-R40, spot welding was performed at a welding current of 8 kA, a pressure of 1.96 kN, and a welding time of 12 cycles. The number of consecutive hits was evaluated by the score.
[0044]
(2) The interlayer resistance value of the coating layer was measured by a grounding Lorester 4-probe method.
[0045]
(3) Formability
(a) Cylindrical Deep Drawing Test A molding test was conducted with a drawing ratio of 2.0 using a cylindrical punch with a diameter of 50 mm by a hydraulic molding tester. The test was conducted after leaving the rust preventive oil to stand for 1 hour to 1 hour 30 minutes. The wrinkle suppressing pressure at this time was 9.8 kN. The evaluation of formability was based on the following index.
[0046]
A: Molding is possible and there are no coating defects. The processing part is completely normal with no shininess.
[0047]
○: Molding is possible and slight wrinkles occur in the coating film. Although a change in color tone is observed in the coated part, no cracks or peeling is observed.
[0048]
Δ: Molding is possible, but large wrinkles and cracks are observed in the coating film.
[0049]
X: Molding is not possible.
[0050]
(b) Bead pull-out test Using a round bead mold with a convex R4mm-shoulder R2mm, standing for 1 hour to 1 hour 30 minutes after application of rust preventive oil, and then bead pull-out test with a holding load of 9.8kN The scratch resistance was evaluated. The evaluation of scratch resistance was based on the following index.
[0051]
A: No coating film defect. The state of the film is completely normal, with no glossy spots on the processed part.
[0052]
○: Slight wrinkles occur in the coating film. Although a change in color tone is observed in the coated part, no cracks or peeling is observed.
[0053]
Δ: The coating film has large wrinkles and cracks.
[0054]
X: Molding is not possible.
(4) Corrosion resistance evaluation After the painted steel sheet was cylindrical deep drawn so that the coated surface was on the outside, a cyclic corrosion test was conducted. The cylindrical deep drawing conditions are the same as in (3).
[0055]
In addition, a cycle corrosion test was conducted after drawing out the bead so that the coating film surface was on the protruding portion protruding side. The bead extraction condition is the same as (3).
[0056]
In addition, a cyclic corrosion test was performed with the cut end face of the flat plate exposed.
[0057]
The cycle corrosion test was carried out with a total of 8 hours consisting of 2 hours of salt spray, 4 hours of drying and 2 hours of wetting as one cycle. The salt spray conditions were in accordance with JIS-K5400. Drying conditions are a temperature of 50 ° C. and a humidity of 30% RH or less, and wet conditions are a temperature of 35 ° C. and a humidity of 95% RH or more.
[0058]
The evaluation of corrosion resistance was based on the following indicators.
[0059]
(a) Cylindrical deep-drawn material: Number of cycles until red rust occurs
(b) Bead drawing material: Number of cycles until red rust occurs.
[0060]
(c) Flat plate end face: State of the end face after CCT100 cycle ◎: When red rust does not occur and white rust indicating corrosion of the plating layer covers less than 5% of the sample ○: Red rust does not occur , When white rust indicating corrosion of the plating layer covers 5% or more and less than 50% of the sample △: Slight red rust is generated, White rust is 50% or more ×: Red rust is generated When it is seen more than 20%
(Example 1)
Various conductive particles were prepared, and pulverized with a pulverizer according to conditions to produce particles with various particle size distributions. A predetermined amount of this conductive particle was mixed with urethane-epoxy resin, applied onto a metal plate, baked and dried. In some cases, an organic coating was applied after applying a base coating on a metal plate. Table 1 shows the conditions. The drying condition at this time is 210 ° C. at the ultimate plate temperature. The coated metal plate thus obtained was evaluated for weldability, formability, and corrosion resistance under the above-described conditions.
[0061]
[Table 1]

[0062]
The results are shown in Table 2. As shown in the examples of the present invention, by controlling the particle size distribution of the conductive particles within the range of 0.05 to 1.0 μm in the particle size distribution mode, and the addition amount to 15 to 60% by volume, it is favorable. Weldability, formability, and corrosion resistance can be secured. In addition, the content of the number distribution mode is set to 5% by volume or more, the volume distribution mode is controlled within the range of 2 to 20 μm, or the maximum particle size and film thickness of the conductive particles are appropriately set. By controlling to a value, better weldability, formability, and corrosion resistance can be secured.
[0063]
The comparative examples of Nos. 1, 10, 11, 14, 27, and 29 showed examples of coated metal plates that deviated from the examples of the present invention. No. 1 has a small amount of conductive particles and does not provide conductivity. No. 10 has too much conductive particles, resulting in poor moldability. No. 11 has a low number distribution mode value, and the conductivity decreases. Nos. 14, 27, and 29 have large number distribution mode values, and thus formability and corrosion resistance are reduced.
[0064]
[Table 2]

[0065]
(Example 2)
Table 3 shows the conditions when various conductive particles or rust preventive pigments are mixed, and when the resin system is changed. Conductive particles and anti-corrosion pigment are mixed in a predetermined amount with urethane-epoxy resin, polyester-melamine resin, polyester-urethane resin, acrylic-polyester resin, polyethylene terephthalate resin, and high-molecular polyester resin, on a metal plate After coating, it was baked and dried. Other coated metal plate manufacturing methods are the same as those in Example 1. The obtained coated metal plate was evaluated for weldability, formability, and corrosion resistance under the same conditions as in Example 1.
[0066]
[Table 3]

[0067]
The results are shown in Table 4. When stainless steel particles having a large particle diameter are added, if the content of the stainless steel particles is 5% by volume or less, well-balanced weldability, formability, and corrosion resistance can be obtained without reducing formability. When added in an amount of 10% by volume or more, processability is slightly lowered. Further, when the rust preventive pigment is 20% by volume or less, good corrosion resistance can be obtained without reducing weldability and formability. Moreover, favorable weldability can be obtained by using a thermoplastic resin.
[0068]
The comparative examples of Nos. 38 to 40 and 48 showed examples of coated metal plates outside the scope of the present invention. In No. 39, the amount of conductive particles is too small, and conductivity cannot be obtained. No. 38 and No. 40 have too large number distribution mode values, and formability and corrosion resistance are greatly reduced. In No. 48, the amount of conductive particles is too large, and the moldability is greatly reduced.
[0069]
[Table 4]

[0070]
(Example 3)
Table 5 shows an example of evaluating the suitability as a fuel tank material for a metal plate coated with a urethane-epoxy resin film containing conductive particles having a controlled particle size distribution or other particles. In addition to the performance evaluation items of Example 1 excluding end face corrosion resistance, the seam weldability shown below and the corrosion resistance test simulating the tank inner surface side were performed.
[0071]
(5) Seam weldability Using an electrode wheel with a tip R6mm-φ250mm, after performing 10m seam welding with a welding current of 11kA, pressurizing force of 4.9kN, and current of 2on-1off, a test piece shown in JIS-Z-3141 was prepared. And a leak test was conducted.
[0072]
◎: No leakage ○: No leakage, but the weld surface is slightly rough △: No leakage, but a defect such as a crack in the weld surface ×: Leak
(6) Internal corrosion resistance The corrosion resistance against gasoline was evaluated. In the method, a test solution was put into a flat bottom cylindrical deep drawn sample having a flange width of 20 mm, a diameter of 50 mm, and a depth of 25 mm using a hydraulic molding tester, and the sample was covered with glass through a silicon rubber ring. The corrosion state after this test was visually observed.
[0073]
(Test conditions)
Test solution: gasoline + 10% distilled water + 200 ppm formic acid
Test period: left at 40 ℃ for 3 months
(Evaluation criteria)
◎: No change ○: White rust occurrence 1% or less △: Red rust occurrence 5% or less, or white rust occurrence 1 ~ 50%
×: Red rust generation over 5% or white rust remarkable [0074]
[Table 5]

[0075]
The results are shown in Table 6. It was found that a coated metal plate in which conductive particles or other particles are controlled to have an appropriate particle size distribution and content provides good weldability, formability, and corrosion resistance, and is also suitable as a fuel tank material.
[0076]
The comparative examples of N0.54, 59, 62, and 67 showed a coated metal plate that departed from the present invention. Nos. 54 and 62 have a small amount of conductive particles and poor weldability. Nos. 59 and 67 have a large number distribution mode of conductive particles, and have poor moldability and corrosion resistance.
[0077]
[Table 6]

[0078]
【The invention's effect】
From the above results, the coated metal plate containing conductive particles with controlled particle size distribution according to the present invention is used for home appliances, OA equipment, civil engineering / building materials, automotive parts, and other parts that require grounding. Since it can be used widely and easily, and it is possible to secure good moldability and corrosion resistance, it is expected to be applied in various applications and greatly contributes to various industrial fields.

Claims (9)

  In a metal plate in which a coating layer in which the binder component containing conductive particles is an organic resin is formed on at least one side, the mode of the number distribution of the conductive particles is in the range of 0.05 to 1.0 μm and the coating A coated metal plate excellent in conductivity, corrosion resistance and formability, wherein the content of conductive particles in the layer is 15 to 60% by volume. Coating of claim 1 wherein the particles falling within the range of ± 0.025 .mu.m for the mode of the number distribution of the conductive particles, a percentage of the total number of the conductive particles is equal to or not less than 5% Metal plate.   3. The coated metal plate according to claim 1, wherein a mode value in a volume distribution for each particle diameter of the conductive particles is 2 to 20 μm.   4. The coated metal plate according to claim 1, wherein the coating layer has an average thickness of 2 to 20 [mu] m.   5. The coated metal plate according to claim 1, wherein the maximum particle size of the conductive particles is 25 μm or less.   6. The coated metal plate according to claim 1, wherein the conductive particles are ferrosilicon.   The coated metal sheet according to any one of claims 1 to 6, wherein the binder component in the coating layer contains a resin containing a urethane bond as a main component.   8. The coated metal plate according to claim 1, wherein the binder component in the coating layer contains a thermoplastic resin as a main component.   9. The coated metal plate according to claim 1, wherein the coating layer contains 20% by volume or less of a rust preventive pigment and / or silica.