JP5028178B2 - Conductive pre-coated aluminum alloy plate - Google Patents

Description

  The present invention relates to a precoated aluminum alloy plate having excellent electrical conductivity used for, for example, a housing for electric equipment.

  Conventionally, a pre-coated aluminum alloy plate obtained by coating the surface of an aluminum alloy plate with a synthetic resin paint has excellent characteristics that it is excellent in corrosion resistance, lightweight, and does not need to be painted after molding. Yes. For this reason, pre-coated aluminum alloy plates are widely used as materials for housings of electronic devices such as home appliances and OA devices.

  On the other hand, these electronic devices often generate electromagnetic waves, and a member used for a housing or the like requires a conductive member in order to suppress the adverse effects of the electromagnetic waves. When a general resin is coated on the surface of an aluminum alloy plate, it becomes charged and causes various electronic troubles. For this reason, the synthetic resin paint (organic resin-based paint) has conductivity.

Therefore, conventionally, various metal-coated plates having the following conductivity have been proposed.
Patent Document 1 and Patent Document 2 disclose a composite coated aluminum plate on which an organic film containing a predetermined ratio of a conductive material such as iron phosphide, graphite, and carbon black is formed.
Patent Document 3 discloses a conductive pre-coated metal plate on which a coating film containing a metal oxide is formed.

  Patent Document 4 discloses an aluminum alloy plate on which an organic resin layer containing a predetermined proportion of carbon black is formed.

Patent Document 5, Patent Document 6, Patent Document 7, and Patent Document 8 propose that a flaky, scaly or spherical Ni filler is contained in the coating film.
In Patent Document 9, Patent Document 10, and Patent Document 11, an aluminum plate in which Ni fine particles are contained in a coating film is proposed.
Patent Document 12 proposes an aluminum plate with a resin film containing Zr.

  However, in recent years, it has become more and more necessary to suppress the adverse effects of electromagnetic waves as the accuracy of personal computers and the improvement of the environment progress. Therefore, conventional conductive resins cannot cope with the conductivity and the probability of conduction by electrode contact.

JP-A-5-309331 JP-A-5-31454 JP 7-313930 A Japanese Patent Laid-Open No. 7-90604 JP 2004-68042 A JP-A-5-320934 JP-A-5-65664 JP-A-7-246679 Japanese Patent Laid-Open No. 7-2111131 JP-A-7-314601 JP-A-8-267656 JP 2001-205730 A

  By the way, in any of the conventional techniques described above, it is necessary to contain a large amount of various conductive substances as described above in the organic resin. On the other hand, these conductive substances become foreign substances that deteriorate the performance of the coating film in the organic resin. That is, due to the presence of a large amount of foreign matter in the coating film, the ratio of the organic resin that plays the role of the binder is reduced, and the adhesion and moldability of the coating film are greatly reduced.

In addition, the electrical conductivity has a problem that its value is not stable due to variations in the distribution of the conductive material.
As described above, ultrafine particles are required that allow the conductive material to conduct and be retained even with a very thin film thickness. In addition, the resin film itself needs to be a film having a property of becoming an ultrathin film uniformly on a microscopic scale.

  Furthermore, in recent years, for example, in addition to higher performance and smaller size and weight of the apparatus, safety to the human body has been emphasized, and there is an increasing demand for suppressing electromagnetic waves from electronic devices. For this reason, the request | requirement of electroconductivity has become stronger than before.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a conductive precoated aluminum alloy sheet having excellent conductivity.

The present invention comprises a substrate made of an aluminum alloy plate, a conversion coating formed on one or both sides of the substrate, and a conductive layer formed on the conversion coating,
The conductive layer is made of a base material made of water glass or polyvinyl alcohol resin,
The thickness T of the conductive layer is 0.05 μm to 1.0 μm,
The surface roughness Ra of the substrate is 0.1 μm to 0.8 μm,
The ratio between the surface roughness Ra of the film thickness T and the substrate of the conductive layer (T / Ra) is Ri 0.07 to 4.0 der,
The conductive layer is a conductive precoated aluminum alloy plate characterized by further containing colloidal silica having a primary particle diameter of 5 nm to 80 nm (Claim 1).

  In the present invention, as described above, the conductive layer has a very thin film thickness T of 0.05 μm to 1.0 μm. The conductive layer does not have a structure in which a large amount of conductive material is dispersed as in the prior art, but the conductive layer itself has conductivity. Therefore, conductivity can be obtained while suppressing a decrease in the adhesion of the coating film. Moreover, since the coating film itself has electrical conductivity, very excellent electrical conductivity is obtained with almost no variation in electrical conductivity.

  In addition, as described above, the conductive layer is made of water glass or polyvinyl alcohol resin, and since these are relatively hydrophilic, it is easy to adsorb moisture on the resin surface and allow moisture to be taken into the resin. It becomes easy. Further, the presence of moisture on the resin surface and in the resin can cause a phenomenon that ions or electrons migrate in the moisture, thereby improving conductivity.

Further, as described above, a conductive layer having a film thickness T of 0.05 μm to 1.0 μm is formed on the substrate having a surface roughness Ra of 0.1 μm to 0.8 μm using the specific base material. In addition, a configuration in which the ratio (T / Ra) of the film thickness T of the conductive layer to the surface roughness Ra of the substrate is set to 0.07 to 4.0 will be described later. As shown in the examples, excellent conductivity can be obtained.
Thus, according to this invention, the electroconductive precoat aluminum alloy plate which has the outstanding electroconductivity can be obtained.

As described above, the conductive precoated aluminum alloy plate of the present invention comprises a substrate made of an aluminum alloy plate, a chemical conversion film formed on one or both surfaces of the substrate, and a conductive layer formed on the chemical conversion film.
Various aluminum alloys can be applied as the aluminum alloy used as the substrate in the present invention depending on the application. Specifically, there are 5000 series, 6000 series and other various alloy systems.
Moreover, since the high intensity | strength electroconductive precoat aluminum alloy plate is obtained, it is preferable that the said board | substrate contains 1.0-5.0 mass% of Mg ( Claim 7 ).

  In addition, as the chemical conversion film formed on the substrate, chromate treatment such as phosphate chromate and chromate chromate, titanium phosphate other than chromium compounds, zirconium phosphate, molybdenum phosphate, zinc phosphate, zirconium oxide, etc. A film obtained by chemical film treatment such as non-chromate treatment, so-called chemical conversion treatment, is employed.

The presence of the base treatment layer made of this chemical conversion film can effectively improve the adhesion between the substrate made of an aluminum alloy plate and the synthetic resin coating film as the conductive layer. In addition, excellent corrosion resistance is realized, and corrosion under the coating caused when corrosive substances such as water and chlorine compounds permeate the surface of the aluminum alloy plate is suppressed, and prevention of coating cracking and peeling is prevented. Can be achieved.
The chemical conversion treatment methods such as chromate treatment and non-chromate treatment include a reaction type and a coating type, but any method may be adopted in the present invention.

The conductive layer is made of a base material made of water glass or polyvinyl alcohol resin.
The water glass is an alkali silicate salt obtained by melting silicon dioxide and alkali, or an aqueous solution thereof, for example, SiO ₂ · K ₂ O, SiO ₂ · Li ₂ O, SiO Examples include ₂ · Na ₂ O.

The conductive layer has a film thickness T of 0.05 μm to 1.0 μm.
Moreover, when the film thickness T of the conductive layer exceeds 1.0 μm, the electrical resistance of the conductive layer increases and the conductivity decreases, and the moldability of the coating film such as press moldability may decrease. There is. The lower limit value of the film thickness T was set to 0.05 μm because the corrosion resistance was maintained.

Further, the surface roughness Ra of the substrate under the chemical conversion film is 0.1 μm to 0.8 μm.
When the surface roughness Ra of the substrate is less than 0.1 μm, it is difficult to produce industrially and the conductivity may be lowered. On the other hand, when the surface roughness Ra exceeds 0.8 μm, the coating layer breakage phenomenon that the conductive layer cannot cover the substrate occurs, and the corrosion resistance, press workability, scratch resistance, fingerprint resistance, etc. are reduced. There is a fear.

The ratio (T / Ra) between the film thickness T of the conductive layer and the surface roughness Ra of the substrate is 0.07 to 4.0.
When the T / Ra is less than 0.07, there is a problem that the corrosion resistance, press workability, scratch resistance, and fingerprint resistance are deteriorated. On the other hand, when the T / Ra exceeds 4.0. In addition to being difficult to produce industrially, there is a problem that conductivity is lowered.

  The method for applying the conductive layer coating material constituting the conductive layer is not particularly limited, and various known methods such as a roll coating method, a bar coating method, a dip coating method, and a spray method are adopted. Yes. In addition, regarding the curing conditions for obtaining a conductive layer that is cured after applying the conductive layer coating material, that is, baking conditions, various conditions should be selected depending on the type of the conductive layer coating material. Can do.

  Moreover, although the said conductive layer consists of a base substance which consists of water glass or polyvinyl alcohol resin, in the range which does not prevent the above-mentioned effect, the primary particle diameter mentioned later is 5 nm-80 nm further as needed. Colloidal silica, a surfactant, an inner wax, nanocarbon particles and the like may be contained.

The conductive layer further contains colloidal silica having a primary particle diameter of 5 nm to 80 nm .
In this case, the conductivity of the conductive precoated aluminum alloy plate can be further improved.

The colloidal silica is colloidal particles in which negatively charged amorphous silica particles are dispersed in water. Surface The -SiOH groups on the particle, -OH ^- ion present, the electric double layer is formed by alkali ions, colloidal silica solution has a stable state by repulsion between the particles.

  When the primary particle diameter of the colloidal silica is less than 5 nm, the electrical resistance may increase and the conductivity may decrease. On the other hand, when the primary particle diameter of the colloidal silica exceeds 80 nm, the adhesion between the chemical conversion film and the coating film may be lowered, and the fingerprint resistance may be lowered.

  If the colloidal silica is contained even in a small amount, the above-described effects are exhibited. And although electroconductivity improves, since there exists a possibility that the adhesiveness between a chemical conversion film and a coating film may fall, the upper limit of content of colloidal silica is 100 weight part of dry weight of the said whole conductive layer. In this case, it is 90 parts by weight. Moreover, it is preferable that it is 60 weight part or less from the reason that an effect is saturated even if it contains more than it, More preferably, it is 40 weight part or less.

Actually, in order to obtain a desired effect, the colloidal silica is preferably contained in an amount of 1 part by weight or more, more preferably 5 parts by weight or more when the dry weight of the entire conductive layer is 100 parts by weight. It is preferable to do.
The colloidal silica is preferably contained in an amount of 1 to 60 parts by weight, and more preferably 5 to 40 parts by weight, when the dry weight of the entire conductive layer is 100 parts by weight.

Further, the conductive layer further, when the dry weight of the entire conductive layer is 100 parts by weight, the surfactant may contain 10 parts by weight 0.1 parts by weight preferably (claim 2).
In this case, the conductivity of the conductive precoated aluminum alloy plate can be further improved, and the scratch resistance can be improved.

  Moreover, when the content of the surfactant is less than 0.1 parts by weight, the above-described effects may not be sufficiently obtained. On the other hand, the content of the surfactant is more than 10 parts by weight. Although the conductivity is improved, the adhesion between the chemical conversion film and the coating film may be reduced.

Examples of the surfactant include ether type, ester type and ether / ester type surfactants.
Examples of the surfactant include alkylene oxide adducts of mono- or higher valent alcohols, hydrocarbyl ethers of alkylene oxide adducts of mono- or higher alcohols, fatty acid esters of alkylene oxide adducts of mono- or higher valent alcohols, and carboxylic acids. Salts, alkyl sulfonates, alkyl sulfates, alkyl phosphates, fatty acid alkanolamides and the like can be used, and one kind selected from these may be used alone, or two kinds having different structures You may use the above mixture.

  Alcohol oxide adduct of monohydric or higher alcohol, hydrocarbyl ether of alkylene oxide adduct of monohydric or higher alcohol, alcohol constituting fatty acid ester of alkylene oxide adduct of monohydric or higher alcohol, Have six.

Examples of such alcohols include monovalent alcohols having 8 to 23 carbon atoms, and may have a molecular chain, an unsaturated bond, or a cyclic structure in the molecule. Specific examples include octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, ethylphenol, nonylphenol, and the like. These may be used alone or as a mixture thereof.
Neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-2-propyl-1,3- Examples thereof include propanediol and 2,2-diethyl-1,3-propanediol.
Further, from the viewpoint of lubricity and water removability, the alcohol preferably has 12 to 18 carbon atoms.

The alkylene oxide adduct of the above-mentioned monohydric or higher alcohol alkylene oxide adduct, the hydrocarbyl ether of the monohydric or higher alcohol alkylene oxide adduct, the alkylene oxide adduct constituting the fatty acid ester of the monohydric or higher alcohol alkylene oxide adduct is carbon. It is preferable to obtain by addition polymerization of alkylene oxides having 2 to 6 carbon atoms, and it is more preferable to carry out addition polymerization of alkylene oxides having 2 to 4 carbon atoms.
Specific examples of the alkylene oxide having 2 to 6 carbon atoms include ethylene oxide, propylene oxide, 1,2-epoxybutane (α-butylene oxide), 2,3-epoxybutane (β-butylene oxide), Examples include 1,2-epoxy-1-methylpropane and 1,2-epoxyheptane.

The polymerization form of alkylene oxide or the like is not particularly limited, and may be homopolymerization of one type of alkylene oxide, random copolymerization of two or more types of alkylene oxide, block copolymerization, random / block copolymerization, or the like.
Moreover, when adding an alkylene oxide to the polyhydric alcohol which has 2-6 hydroxyl groups, you may add to all the hydroxyl groups, and you may add only to a part of hydroxyl groups.

  Alkylene oxide adduct of monohydric or higher alcohol, hydrocarbyl ether of alkylene oxide adduct of monohydric or higher alcohol, terminal hydroxyl group of alkylene oxide adduct constituting fatty acid ester of alkylene oxide adduct of monohydric or higher alcohol A part or all of the above can be hydrocarbyl etherified.

Here, the hydrocarbyl group is a hydrocarbon group having 1 to 24 carbon atoms.
Examples of the hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group.

  Examples of the alkyl group having 1 to 24 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, straight chain or branched Pentyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched octyl group, linear or branched nonyl group, linear or branched decyl group, straight Chain or branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched Hexadecyl group, linear or branched heptadecyl group, linear or branched octadecyl group, linear or branched nonadecyl group, linear or branched icosyl group, linear or branched heicosyl group, linear Or a branched docosyl group, linear or branched There tricosyl group, and Tetoraikoshiru group of straight or branched is.

  Examples of the alkenyl group having 2 to 24 carbon atoms include a vinyl group, a linear or branched propenyl group, a linear or branched butenyl group, a linear or branched pentenyl group, and a linear or branched hexenyl group. Group, linear or branched heptenyl group, linear or branched octenyl group, linear or branched nonenyl group, linear or branched decenyl group, linear or branched undecenyl group, linear or Branched dodecenyl group, linear or branched tridecenyl group, linear or branched tetradecenyl group, linear or branched pentadecenyl group, linear or branched hexadecenyl group, linear or branched heptadecenyl group A linear or branched octadecenyl group, a linear or branched nonadecenyl group, a linear or branched icosenyl group, a linear or branched henicosyl group, a linear or branched dococenyl group, a linear or branched group Branch tricocenyl , And there is a tetracosenyl group of straight or branched.

  Examples of the cycloalkyl group having 5 to 7 carbon atoms include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

  Examples of the alkylcycloalkyl group having 6 to 11 carbon atoms include a methylcyclopentyl group, a dimethylcyclopentyl group (including all structural isomers), a methylethylcyclopentyl group (including all structural isomers), a diethylcyclopentyl group ( Including all structural isomers), methylcyclohexyl group, dimethylcyclohexyl group (including all structural isomers), methylethylcyclohexyl group (including all structural isomers), diethylcyclohexyl group (including all structural isomers) Including), methylcycloheptyl group, dimethylcycloheptyl group (including all structural isomers), methylethylcycloheptyl group (including all structural isomers), and diethylcycloheptyl group (including all structural isomers) ) Etc.

  Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

  Examples of the alkylaryl group having 7 to 18 carbon atoms include a tolyl group (including all structural isomers), a xylyl group (including all structural isomers), and an ethylphenyl group (including all structural isomers). , Linear or branched propylphenyl group (including all structural isomers), linear or branched butylphenyl group (including all structural isomers), linear or branched pentylphenyl group (all ), Linear or branched hexylphenyl group (including all structural isomers), linear or branched heptylphenyl group (including all structural isomers), linear or branched Branched octylphenyl groups (including all structural isomers), linear or branched nonylphenyl groups (including all structural isomers), linear or branched decylphenyl groups (including all structural isomers) ), Straight or branched unde Butylphenyl (including all structural isomers) group, and (including all structural isomers) linear or branched dodecylphenyl group and the like.

  Examples of the arylalkyl group having 7 to 12 carbon atoms include benzyl group, phenylethyl group, phenylpropyl group (including propyl group isomers), phenylbutyl group (including butyl group isomers), and phenylpentyl group. (Including isomers of pentyl group), phenylhexyl group (including isomers of hexyl group), and the like.

  As the fatty acid ester of the above alkylene oxide adduct of monohydric or higher alcohol and the fatty acid constituting the hydrocarbyl ether, any of linear saturated fatty acid, branched saturated fatty acid, linear unsaturated fatty acid, branched unsaturated fatty acid is used. May be. In terms of carbon number, those having 7 to 22 carbon atoms are preferred. Specifically, for example, caprylic acid, pelargonic acid, capric acid, methyl laurate, myristic acid, palmitic acid, stearic acid, oleic acid, eicosane An acid etc. are mentioned.

  Examples of the carboxylate include aliphatic monocarboxylate, polyoxyethylene / alkyl ether / carboxylate, N-acyl sarcosine, N-acyl glutamate and the like. Examples of the cationic counter ion forming the salt include metal ions such as alkali metal (sodium, potassium, lithium, etc.) ions, alkaline earth metal (magnesium, calcium, barium, etc.) ions, ammonium ions, and the like.

  Examples of the alkyl sulfonate include dialkyl sulfo-succinate, alkane sulfonate, alpha olefin sulfonate, linear alkyl benzene sulfonate, molecular chain alkyl benzene sulfonate, naphthalene sulfonate- Examples include formaldehyde condensate, alkylnaphthalene sulfonate, N-methyl-N-acyl taurine and the like. Examples of the cationic counter ion forming the salt include metal ions such as alkali metal (sodium, potassium, lithium, etc.) ions, alkaline earth metal (magnesium, calcium, barium, etc.) ions, ammonium ions, and the like.

  Examples of the alkyl sulfate include polyoxyethylene / alkyl ether / sulfate, oil and fat sulfate ester salt, and the like. Examples of the cationic counter ion forming the salt include metal ions such as alkali metal (sodium, potassium, lithium, etc.) ions, alkaline earth metal (magnesium, calcium, barium, etc.) ions, ammonium ions, and the like.

  Examples of the phosphate include alkyl phosphate, polyoxyethylene / alkyl ether / phosphate, polyoxyethylene / alkyl phenyl ether / phosphate, and the like. Examples of the cationic counter ion forming the salt include metal ions such as alkali metal (sodium, potassium, lithium, etc.) ions, alkaline earth metal (magnesium, calcium, barium, etc.) ions, ammonium ions, and the like.

Further, the conductive layer further, when the dry weight of the entire conductive layer is 100 parts by weight, preferably contains 15 parts by weight 0.05 parts by weight of the inner wax (claim 3).
In this case, the presence of the inner wax reduces the surface friction coefficient, which can improve scratch resistance and moldability, reduce the contact angle of oil and moisture, improve fingerprint resistance, etc. Can be achieved.

  When the content of the inner wax is less than 0.05 parts by weight, the effect of improving press formability may not be obtained so much. On the other hand, if it exceeds 15 parts by weight, the inner wax may ooze out and reduce the productivity when the coil is raised in the production process when the conductive pre-coated aluminum alloy plate is mass-produced.

As the inner wax, for example, lanolin, carnauba, polyethylene or the like can be used.
Here, when polyethylene is used as the synthetic resin, it is preferable not to use polyethylene as the inner wax, but to use lanolin, carnauba or the like that is not polyethylene.

The conductive layer may further contain 0.01 to 10 parts by weight of nanocarbon particles having a primary particle diameter of 5 to 100 nm when the dry weight of the entire conductive layer is 100 parts by weight. Preferred ( claim 4 ).
In this case, the conductivity of the conductive precoated aluminum alloy plate can be further improved.

  When the primary particle diameter of the nanocarbon particles is less than 5 nm, the above effects may not be sufficiently obtained. On the other hand, when the primary particle diameter of the nanocarbon particles exceeds 100 nm, the adhesion of the conductive layer may be lowered.

  Moreover, when content of the said nano carbon particle is less than 0.01 weight part, there exists a possibility that the above-mentioned effect may not fully be acquired. On the other hand, when it exceeds 10 weight part, there exists a possibility that production may become difficult industrially.

The conductive pre-coated aluminum alloy plate has an electrical resistance of 10 or more surface sites of 30 Ω or less when measuring the electrical resistance of 20 different surface sites of the conductive layer by the needle electrode method. and, it is preferable that the average value of the electric resistance of the surface portion of the 20 locations is 10Ω or less (claim 5).
In this case, it can utilize suitably for the various uses which require electroconductivity.

  The needle electrode method is a method in which a pure copper needle having a spherical needle tip of φ0.2 mm is placed on the surface of the conductive layer, and a load is applied to the needle so that the needle tip does not penetrate the conductive layer. In this state, the electrical resistance value of the conductive layer of the portion in contact with the needle tip is measured by conducting between the substrate exposed by removing the film and the needle.

When the electrical resistance of 10 or more surface parts exceeds 30Ω among the electrical resistances of the 20 different surface parts, there is a possibility that a part with poor electromagnetic shielding properties may occur.
Moreover, when the average value of the electrical resistance of the 20 different surface portions exceeds 10Ω, there is a possibility that a portion with poor electromagnetic shielding properties may occur.

The surface roughness Ra of the surface of the conductive layer is preferably 0.05Myuemu～0.6Myuemu (claim 6).
When the surface roughness Ra of the surface of the conductive layer is less than 0.05 μm, the scratch resistance and fingerprint resistance may be reduced. On the other hand, when the surface roughness Ra exceeds 0.6 μm, The film thickness at the top tends to be thin, and the corrosion resistance may deteriorate.

Further, the conductive precoat aluminum alloy plate is preferably used for electrical equipment housing or an electronic equipment housing (claim 8).
In this case, an excellent electrical device casing or electronic device casing can be obtained by taking advantage of the excellent electrical conductivity and fingerprint resistance described above.

  Examples of the electrical device casing or the electronic device casing include, for example, a personal computer body, a casing of an electronic device such as a CD-ROM, a DVD, and a PDA, a casing of an electric device such as a television, FDD, MD, There are various other things such as the shutter part of a storage medium case such as MO.

Example 1
In this example, an example and a comparative example according to the conductive precoated aluminum alloy plate of the present invention will be described.
In this example, the chemical conversion film, the configuration of the conductive layer, and the like are changed, and as the present invention product, 20 types of conductive pre-coated aluminum alloy plates (sample E1 to sample E20) shown in Table 2, and as a comparative product, Table 3 6 types of conductive pre-coated aluminum alloy plates (Sample C1 to Sample C6) were prepared, and various performance evaluation tests were performed.
This will be described in detail below.

As shown in FIG. 1, the conductive pre-coated aluminum alloy plates 1 of Sample E1 to Sample E20 all have a substrate 2 made of an aluminum alloy plate, a chemical conversion film 3 formed on one or both surfaces of the substrate 2, and the chemical conversion The conductive layer 4 is formed on the film 3.
Samples C1 to C6 have the same basic configuration as Samples E1 to E20.

  In producing these samples E1 to E20 and C1 to C6, first, a 5052-H34 material having a plate thickness of 1.0 mm was prepared as the substrate 2 made of an aluminum alloy plate. The substrate 2 was changed in surface roughness Ra within a range of 0.05 to 0.9.

Next, a chemical conversion film treatment for forming the chemical conversion film 3 was performed on the substrate 2. Table 1 shows four types of chemical conversion treatments (ad) adopted in this example.
In the chemical conversion treatment a, a reactive chromate film is formed by phosphoric acid chromate treatment so that the chromium amount becomes 20 mg / m ² . Specifically, chemical conversion treatment was performed by a soaking method in which a sample was immersed in a chemical conversion treatment solution, and then dried in an atmosphere of about 100 ° C.

In the chemical conversion treatment b, a reactive non-chromate film is formed by zirconium treatment so that the amount of zirconium becomes 20 mg / m ² . The treatment method is the same as the chemical conversion treatment a.

In the chemical conversion treatment c, a coating-type chromate film is formed by coating-type chromate treatment so that the amount of chromium is 20 mg / m ² . Specifically, after the substrate was degreased, a treating agent was applied by a bar coating method, and then dried in an atmosphere of about 100 ° C.
In the chemical conversion treatment d, a coating-type non-chromate film is formed by coating-type zirconium treatment so that the amount of zirconium is 20 mg / m ² . The processing method is the same as the chemical conversion treatment d.

  Next, the conductive layer 4 was formed on the chemical conversion film 3 described above. There are various methods as described above for coating the conductive layer paint. In this example, the bar coating method is used, and then a baking process is performed in which the substrate surface temperature is maintained at about 230 ° C. for 40 seconds. Then, a conductive layer having the composition and film thickness T shown in Tables 2 and 3 was formed.

The conductive layer coating material includes a base material, colloidal silica, a surfactant, an inner wax, and the like containing a coating composition containing solid components such as those shown in Tables 2 and 3, with isopropyl alcohol as a solvent, It was prepared using ethyl alcohol and ethylene glycol mononormal butyl ether.
The base substance content, colloidal silica content, inner wax content, and nanocarbon particle content in Tables 2 and 3 are weights relative to 100 parts by weight of the entire conductive layer after drying.

Two types of polyvinyl alcohol and water glass were prepared as the base materials constituting the conductive layer.
In Table 2 and Table 3,
Polyvinyl alcohol: A,
Water glass (SiO ₂ · Na ₂ O): indicated as B

As colloidal silica, three types of colloidal silica having primary particle systems of 3 nm, 30 nm, and 85 nm were prepared.
Two types of surfactants were prepared: butyl oxyethylene palmitate and sodium sulfonate.
In Table 2 and Table 3,
Oxyethylene palmitic acid butyl ester: EO,
Sodium sulfonate: indicated as NS

Moreover, polyethylene was prepared as an inner wax.
In Table 2 and Table 3,
Polyethylene: indicated as PE.

  Further, as is known from Table 2, in Samples E1 to E20, the conductive layer is made of a base material made of water glass or polyvinyl alcohol resin, and the film thickness T of the conductive layer is 0.05 μm to 1.0 μm. The surface roughness Ra of the substrate is 0.1 μm to 0.8 μm, and the ratio (T / Ra) between the film thickness T of the conductive layer and the surface roughness Ra of the substrate is 0.07 to 4.0. It turns out that it is in the range.

Next, in this example, the following various evaluation tests and the like were performed on the 26 types of samples (Sample E1 to Sample E20 and Sample C1 to Sample C6) shown in Tables 2 and 3. The results are shown in Table 4.
<Conductivity>
The conductivity was evaluated by measuring the electrical resistance values of 20 surface portions with different conductive layers by the needle electrode method. In the needle electrode method, a pure copper needle having a spherical needle tip of φ0.2 mm is placed on the surface of the conductive layer, and a load is applied to the needle so that the needle tip does not penetrate the conductive layer. In this method, the electrical resistance value of the conductive layer at the portion where the needle tip is in contact is measured by conducting between the substrate exposed by removing the film and the needle. In this example, the load applied to the needle was uniformly set to 10 g. A case where the evaluation was 3 points or more was passed, and a case where the evaluation was 2 points or less was rejected.

(Evaluation criteria)
5 points: When the measured electrical resistance value is 30% or less, the ratio is 100%.
4 points: When the measured electric resistance value is 30Ω or less and the ratio is 80% or more and less than 100%.
3 points: When the measured electric resistance value is 30Ω or less and the ratio is 50% or more and less than 80%.
2 points: When the measured electrical resistance value is 30Ω or less and the ratio is 30% or more and less than 50%.
1 point: When the ratio of the measured electric resistance value of 30Ω or less is 10% or more and less than 30%.
0 point: When the measured electrical resistance value is 30Ω or less and the ratio is less than 10%.

<Press workability>
As shown in FIG. 2, the press workability was evaluated by the number of times that each sample 50 was repeatedly bent and the number of bendings at which the coating film cracking of the conductive layer in the bent portion disappeared.
There are 5 evaluation points: 5 points for 1 bend, 4 points for 2 bends, 3 points for 3 bends, 2 points for 4 bends, 5 bends The number of times was 1 point. The case where the evaluation score was 3 points or more was determined to be acceptable, and the case where the evaluation score was 2 points or less was determined to be unacceptable.

<Scratch resistance>
The scratch resistance was determined by the Bowden test shown in FIG. That is, a hard ball 51 having a diameter of ¼ inch under a load of 100 g was slid on the surface of the conductive layer of the sample 50 placed on the sample table 59, and evaluation was performed by the number of sliding times when the coating film was broken. .
There are 5 grades: 5 points for sliding times of 100 times or more, 4 points for sliding times of 75 times to less than 100 times, 3 points for sliding times of 50 times to less than 75 times, The case where the number of movements is 25 times or more and less than 50 times is 2 points, and the case where the number of movements is less than 25 times is 1 point. The case where the evaluation score was 3 points or more was determined to be acceptable, and the case where the evaluation score was 2 points or less was determined to be unacceptable.

<Solvent resistance>
Solvent resistance is as follows: 1 pound hammer is covered with 5 layers of waste cloth, soaked with trichlorethylene, placed on the surface of the conductive layer of each sample, repeatedly slid 50 mm long, and the coating surface is dissolved and discolored several times. Observed what to do.
There are 5 grades, 5 points for 10 times or more, 4 points for 7 times or more and less than 10 times, 3 points for 5 times or more and less than 7 times, 2 points for 2 times or more and less than 5 times In the case of one point, one point was set. The case where the evaluation score was 3 points or more was determined to be acceptable, and the case where the evaluation score was 2 points or less was determined to be unacceptable.

<Comprehensive evaluation>
Comprehensive evaluation is a case where all the items of conductivity, press workability, scratch resistance, and solvent resistance are acceptable (evaluation ○), and the conductivity, press workability, scratch resistance, solvent resistance A case where any of the items of the property was rejected was regarded as rejected (evaluation x).

As can be seen from Table 4, the samples E1 to E20 as the products of the present invention exhibited excellent characteristics in all evaluation items.
From this, according to this invention, it turns out that the electroconductive precoat aluminum alloy plate which has the outstanding electroconductivity can be obtained.

  On the other hand, as can be seen from Table 4, samples C1 and C5 as comparative products have a thickness T and (T / Ra) of the conductive layer below the lower limit of the present invention, so that press workability, scratch resistance, Solvent property was unacceptable.

Moreover, since the film thickness T of the conductive layer exceeded the upper limit of the present invention, the sample C2 as a comparative product was unsuccessful because the electrical resistance of the conductive layer was increased and the conductivity was not obtained.
Moreover, since the surface roughness of the substrate of the sample C3 as a comparative product was below the lower limit of the present invention, the conductivity was unacceptable.

Moreover, since the surface roughness of the substrate exceeded the upper limit of the present invention, the sample C4 as a comparative product failed in press workability, scratch resistance, and solvent resistance.
Moreover, since the sample C6 as a comparative product (T / Ra) exceeds the upper limit of this invention, electroconductivity was not acquired and it was disqualified.

Explanatory drawing which shows the structure of the electroconductive precoat aluminum alloy plate in an Example. Explanatory drawing which shows the evaluation method of press workability in an Example. Explanatory drawing which shows the Bowden test method which is an evaluation method of scratch resistance in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive precoat aluminum alloy plate 2 Substrate 3 Chemical conversion film 4 Conductive layer

Claims (8)

A substrate made of an aluminum alloy plate, a chemical conversion film formed on one or both surfaces of the substrate, and a conductive layer formed on the chemical conversion film,
The conductive layer is made of a base material made of water glass or polyvinyl alcohol resin,
The thickness T of the conductive layer is 0.05 μm to 1.0 μm,
The surface roughness Ra of the substrate is 0.1 μm to 0.8 μm,
The ratio between the surface roughness Ra of the film thickness T and the substrate of the conductive layer (T / Ra) is Ri 0.07 to 4.0 der,
The conductive layer further contains colloidal silica having a primary particle diameter of 5 nm to 80 nm, the conductive precoated aluminum alloy plate.   The conductive precoat according to claim 1, wherein the conductive layer further contains 0.1 to 10 parts by weight of a surfactant when the dry weight of the entire conductive layer is 100 parts by weight. Aluminum alloy plate.   3. The conductive layer according to claim 1, wherein the conductive layer further contains 0.05 to 15 parts by weight of an inner wax when the total dry weight of the conductive layer is 100 parts by weight. Pre-coated aluminum alloy plate.   In any 1 item | term of Claims 1-3, when the said conductive layer further makes the dry weight of the said whole conductive layer 100 weight part, the nanoparticle particle | grains whose primary particle diameters are 5-100 nm are 0.01. A conductive pre-coated aluminum alloy plate comprising 10 parts by weight to 10 parts by weight.   In any one of Claims 1-4, when the electrical resistance of 20 surface parts from which the said conductive layer differs by the acicular electrode method is measured, the electrical resistance of 10 or more surface parts is 30 ohms or less. And the average value of the electrical resistance of said 20 surface site | parts is 10 ohms or less, The electroconductive precoat aluminum alloy plate characterized by the above-mentioned.   6. The conductive precoated aluminum alloy plate according to claim 1, wherein the surface roughness Ra of the surface of the conductive layer is 0.05 μm to 0.6 μm.   The conductive precoated aluminum alloy plate according to any one of claims 1 to 6, wherein the substrate contains 1.0 to 5.0 mass% of Mg.   The conductive precoated aluminum alloy plate according to any one of claims 1 to 7, wherein the conductive precoated aluminum alloy plate is used for a casing for an electric device or a casing for an electronic device.

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