JP3328175B2 - Magnetic shield material and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shield material, and more particularly, to a magnetic shield material formed by cold working such as a motor case.

[0002]

2. Description of the Related Art In an electric device, a magnetic shielding material is mounted inside or outside the device separately from a case or a cover in order to shield a leakage magnetic flux. For example, audio equipment, OA
In a small motor used for a device, a VTR, or the like, a magnetic shield material is attached to the motor in order to shield a leakage magnetic flux. In recent years, the size has been further reduced, and strict processing has been required for the magnetic shield material to be mounted.

[0003] As the performance required for the magnetic shield material,
Magnetic shielding properties, beautiful appearance and corrosion resistance. In order to enhance the magnetic shielding property, it is effective to increase the magnetic permeability. In steel, the crystal grain size is increased, and as the content of Si and Al increases, the magnetic permeability increases. Therefore, from the viewpoint of magnetic shielding properties, the use of directional silicon steel having high magnetic permeability is effective. And it is common to apply a paint to the surface in order to improve the beauty of appearance and corrosion resistance.

If a steel material having high magnetic permeability can be used for a case or a cover of an electric device, it can also serve as a magnetic shielding material, and it is not necessary to separately mount a magnetic shielding material. However, since the case and the cover are subjected to a cold working with a high strength such as a drawing process or a bending process, a steel material having a high magnetic permeability, for example, a directional silicon steel plate, has low workability, and cracks and breaks occur, which is severe. There were problems that the molding process could not be tolerated, the forsterite film formed on the surface was easily peeled off, the coating film was easily peeled off, and the magnetic shielding property was deteriorated with the processing.

To solve the above problem, for example, Japanese Patent Laid-Open No.
No. 26 discloses that a steel containing 4.5% or less in total of Si and / or Al is made into a steel sheet having a recrystallized structure having a crystal grain size of 30 μm or less, then subjected to cold working, and then subjected to a heat treatment to reduce the crystal grains. A method for manufacturing a magnetic shield material to be coarsened has been proposed. However, in this method, the recrystallization annealing is performed after the cold working, so that the annealing efficiency is reduced and the productivity is deteriorated.

Japanese Unexamined Patent Publication (Kokai) No. 5-239694 proposes a grain-oriented silicon steel sheet for magnetic shielding having excellent coating adhesion. This steel plate is characterized in that the thickness of the forsterite coating on the ground iron is limited and the paint is applied directly on the coating. Oriented silicon steel sheets are usually provided with a forsterite coating and a vitreous coating for imparting tensile stress in the rolling direction to improve iron loss. However, since the vitreous coating is harmful to paint adhesion, the vitreous coating is not applied to the silicon steel sheet for magnetic shielding described in JP-A-5-239694.

[0007] However, the absence of a vitreous coating causes the stress state of the paint surface to greatly affect the stress state of the ground iron. As a result, depending on the state of contact between the steel sheets or the state of contact with the jig at the time of forming, strain may be introduced into the surface layer of the ground iron, the magnetic permeability may be reduced, and the magnetic shielding property may be deteriorated. Furthermore, the above-mentioned conventional magnetic shield material has a quality problem that corrosion progresses and rust occurs when used in an environment of high temperature and high humidity.

[0008]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and is excellent in workability with little peeling of a coating film and a decrease in magnetic permeability even when processed, and even in a high-temperature, high-humidity environment. An object of the present invention is to propose a usable magnetic shielding material having excellent corrosion resistance.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the peeling of the coating film and the forsterite film and the decrease in the magnetic permeability that occur during the processing of the coated grain-oriented electrical steel sheet. It was found that the coating properties, especially the basis weight and the coefficient of friction of the film had a great influence. further,
As a result of examining the improvement of the corrosion resistance, it was found that the formation of an intermediate film having corrosion resistance between the forsterite film and the coating film significantly improved the corrosion resistance.

First, two experimental results on which the present invention is based will be described. (Experiment 1) The present inventors assumed a magnetic shield material to be wound around a small motor, and used a 0.23 mm-thick finish-annealed grain-oriented electrical steel sheet, and applied a coating film on corrosion resistance, bending resistance, and magnetic shield property. The effect of the weight per unit area and the coefficient of friction was examined.

The surface of the grain-oriented electrical steel sheet used is about 2 μm
A thick forsterite film was formed. This steel sheet was subjected to flattening annealing at 800 ° C. for 2 minutes. Magnetic properties after _{annealing, W 17/50: 0.95~1.00W / kg,} B 8: 1.85~1.86
It was T. Then, on the forsterite coating of this electrical steel sheet, chromate coating was applied to 10 mg by chromate treatment.
After forming / m ^2, an epoxy resin paint was further applied on the chromate film and baked at 200 ° C. Change the viscosity of the epoxy resin paint by changing the compounding ratio of the epoxy resin and the curing agent and the compounding ratio of the diluted thinner, or further change the application conditions (specifically, change the peripheral speed and plate speed of the application roll). Then, test pieces were prepared in which the basis weight and the friction coefficient of the coating film were changed, and the corrosion resistance, bending resistance, and magnetic shielding property were investigated.

In the corrosion resistance test, a 5% hydrochloric acid solution (liquid temperature: 35) was applied to the surface of each coated steel sheet having a basis weight of 0.5 to 5 g / m ² using a coating film having a static friction coefficient (μ) of 0.2. (± 1 ℃)
Spraying was performed at a flow rate of ２2 ml / hr, and the occurrence of rust was observed. The corrosion resistance was evaluated by the number of days required until rusting occurred. From the results of the corrosion resistance test shown in FIG. 1, it can be seen that when the basis weight of the coating film is less than 2 g / m ² , the number of days required for rusting is short and the corrosion resistance is deteriorated.

In the bending resistance test, a coated steel sheet having a static friction coefficient of 0.2 was used, and each coated steel sheet having a basis weight of 1 to 10 g / m ² was wound around a round bar having a different diameter. The maximum round bar diameter at which peeling is observed is determined, and the bending resistance is evaluated. From the results shown in FIG. 2, it can be seen that when the basis weight of the coating film exceeds 8 g / m ² , the bending diameter increases, and the bending workability deteriorates.

Then, the coated steel sheet having a basis weight of 6 g / m ² and a friction coefficient of 0.1 to 0.65 was changed to 20 mmφ.
The coating film appearance was visually observed when the film was wound around a round bar four times and unwound, and the occurrence rate of peeling of the film is shown in FIG. FIG.
From this, it is understood that when the friction coefficient of the coating film exceeds 0.4, the occurrence rate of the coating film peeling increases, and the bending resistance deteriorates. When the friction coefficient of the coating film exceeds 0.4, it can be seen that the coating film peels off due to the rubbing between the steel plates.

In the magnetic shielding test, the basis weight of the coating film was 6
g / m ² , and each coated steel sheet with the friction coefficient changed to 0.1 to 0.65 was wound around a round bar of 25 mmφ five times and formed.
As shown in FIG. 5, the sample was divided and the magnetic field of the permanent magnet 1 was cut off by the sample 2, and the Gaussian measuring device 3, the conducting wire 4, and the meter 5 were used.
Was used to measure the strength of the magnetic field. The magnetic shielding property was evaluated from the measured magnetic field strength. The strength of the magnetic field of the permanent magnet is 500 A / m. FIG. 4 shows the measurement results. From FIG. 4, it can be seen that when the coefficient of friction of the coating film exceeds 0.4, the strength of the measured magnetic field increases, and the magnetic shielding properties deteriorate. It is considered that the higher the coefficient of friction of the coating film, the greater the shear strain introduced into the surface layer of the ground iron due to the rubbing of the steel sheets during the forming process and the lower the magnetic permeability. (Experiment 2) An experiment was carried out using the same finish-annealed grain-oriented electrical steel sheet as used in Experiment 1.

On the forsterite film on the surface of the grain-oriented electrical steel sheet, first, an intermediate film containing chromium oxide is formed in a range of 0 to 120 mg / m ² by chromate treatment. 5 g / m ² by coating
After forming, it was baked to obtain a magnetic shield material. In addition,
The coefficient of friction of the coating was 0.3. For these magnetic shielding materials, corrosion resistance, magnetic shielding properties, bending resistance,
The peel resistance was tested.

The corrosion resistance test was carried out by applying 7
% Hydrochloric acid solution (liquid temperature: 35 ± 1 ° C.) was sprayed at a flow rate of 0.6 to 0.9 ml / hr, and the generation of rust was observed. The corrosion resistance was evaluated by the number of days required until rusting occurred. In the bending resistance test, each coated steel sheet is wound around a round bar with different diameter,
The maximum round bar diameter at which peeling of the coating film was observed was determined, and the bending resistance was evaluated.

[0018] The peeling resistance test was carried out on each coated steel sheet with a diameter of 20 mm.
The film was wound around a round bar four times, molded and unwound, and the appearance of the film was visually observed to determine the rate of occurrence of film peeling, and the peeling resistance was evaluated. In the magnetic shielding test, each coated steel sheet was wound around a round bar having a diameter of 25 mm five times and formed, then divided into two samples, and the magnetic field of the permanent magnet 1 was cut off by the sample 2 as shown in FIG. The intensity of the magnetic field was measured using a measuring device including a Gaussian measuring device 3, a conducting wire 4, and a meter 5. The magnetic shielding property was evaluated from the measured magnetic field strength. The strength of the magnetic field of the permanent magnet is 500 A / m.

The results of the corrosion resistance test are shown in FIG.
Shown with ₈ . FIG. 7 shows the magnetic shielding property, bending resistance, and peeling resistance. From FIG. 6, it can be seen that in order to ensure corrosion resistance, the adhesion amount of the intermediate coating needs to be 5 mg / m ² or more. However, when the adhesion amount of the intermediate coating exceeds 100 mg / m ² , the magnetic flux density B ₈ is remarkably reduced, and the magnetic shielding property is also reduced as can be seen from FIG.
On the other hand, it can be seen that the bending resistance and the peeling resistance do not depend on the adhesion amount of the intermediate coating.

From the above experimental results, the characteristics of the coating film of the magnetic shielding material made of the grain-oriented electrical steel sheet coated with the coating material are considered from the viewpoints of the magnetic shielding property, the bending resistance, and the corrosion resistance.
In particular, it has been found that it is important to regulate the coefficient of friction and the basis weight, and it is important to regulate the amount of adhesion of the intermediate coating from the viewpoint of corrosion resistance. The present invention has been made based on the above findings.

That is, the present invention relates to a magnetic shielding material comprising a grain-oriented electrical steel sheet having a forsterite film, wherein Cu, Cr, Ni, S
at least one of n and Zn or Cu, Cr, N
A corrosion resistant intermediate coating containing at least one compound of i, Sn, and Zn is formed in an amount of 5 to 100 mg / m ² , and an epoxy resin coating, an acrylic resin coating, and
And a coating film having a friction coefficient of 0.4 or less formed by applying one selected from polyester and polyester resin paints to ² to 8 g / m ² , which is excellent in corrosion resistance and workability. Ru magnetic shield material der.

Further, the present invention provides a method for manufacturing a grain-oriented electrical steel sheet having a forsterite coating on a surface of Cu, Cr, Ni, Sn, and Zn.
At least one metal or Cu, Cr, Ni, Sn, Zn
Treatment with a liquid containing at least one of the compounds
30 After the intermediate coating was 5 to 100 mg / m ² formed on the intermediate coating surface at No.4 Ford cup measuring resistant to corrosion by
An epoxy resin paint, an acrylic resin paint or a polyester resin paint having a viscosity of ~ 150 seconds is applied so that the friction coefficient is 0.4 or less and the basis weight of the coating film is ² to 8 g / m2, and baking is performed. Ru manufacturing method der magnetic shielding material having excellent corrosion resistance and workability characterized.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic shielding material of the present invention uses a grain-oriented electrical steel sheet having a forsterite film. The composition of grain-oriented electrical steel sheet is not particularly limited, but Si: 2.8
Silicon steel sheets containing up to 3.4% are preferred. Si is an effective element for improving the magnetic shielding property. However, if it exceeds 3.4%, the cold workability deteriorates, and if it is less than 2.8%, the effect is not recognized. 3.4%
Is desirable.

Further, in addition to Si, it is preferable to contain Al: 10 ppm or less to enhance the magnetic shielding property. A
l: Exceeding 10 ppm causes a decrease in magnetic flux density. Therefore, the upper limit of the Al content is preferably set. In addition, if necessary,
S, Sn, Se, Mo, Sb, Mn and the like can be added in trace amounts. In melting the base material, any known method such as a converter and an electric furnace can be used. The molten steel whose composition has been adjusted is preferably made into a slab by continuous casting, ingot-bulking method, and then to a final thickness by hot rolling and cold rolling.

After the steel sheet rolled to the final thickness is subjected to decarburizing annealing, an annealing separator mainly composed of MgO is applied to the surface and finish annealing is performed. As a result, a forsterite film is formed on the surface, and secondary recrystallized grains having a uniform orientation are formed, so that excellent magnetic properties are obtained. The forsterite film is preferably 3 μm or less from the viewpoint of workability. The magnetic shield material desirably has a high magnetic permeability, and preferably has a magnetic permeability of at least 0.01 H / m at 100 A / m.

The grain-oriented electrical steel sheet with a forsterite coating is preferably subjected to flattening annealing, and then a corrosion-resistant intermediate coating having a thickness of 5 to 100 m is formed on the forsterite coating.
g / m ² to form. Intermediate coating formed on top of the forsterite film is Ri coating der rich in corrosion resistance, Cu, Cr, Ni,
Sn, Zn sac Chino least one metal or Cu, Cr, N
i, Sn, shall be the coating comprising at least one compound of Zn. As a film having high corrosion resistance, for example, a chromate film containing a Cr oxide formed by treating with a chromate solution containing chromic anhydride and phosphoric acid, boric acid, and silicofluoride is excellent in corrosion resistance and is a magnetic shielding material. It is most preferable because it does not have a noticeable adverse effect on the characteristics as Also, Zn (H ₂ PO ₄ ) ₂ , Fe (H ₂ PO ₄ ) ₂ , H ₃ PO ₄ , Zn (NO ₃ ) ₂
A coating containing zinc phosphate formed by treatment with a liquid is also suitable. Needless to say, a film formed by chemical plating or electroplating at least one metal of Cu, Ni, Cr, Sn, and Zn may be used.

If the amount of the intermediate coating is less than 5 mg / m ² , the number of days required until rust is short and the corrosion resistance is reduced as shown in FIG. 6, while if the amount of adhesion exceeds 100 mg / m ² , the magnetic shielding The property is deteriorated. For this reason, the adhesion amount of the intermediate coating is 5 to 100 m
It is desirable to be in the range of g / m ² . A paint is further applied on the intermediate coat to form a coat.

The paint, epoxy resin paint, shall be the acrylic resin paint or polyester resin paint. The epoxy resin paint contains an epoxy resin, a curing agent, an inorganic pigment, and a solvent as main components. As the epoxy resin, a high molecular weight bisphenol A type epoxy resin is preferable. Alternatively, those modified with polyester, urethane, fatty acid or the like may be used. As the curing agent, an alicyclic modified amine,
An aliphatic amine, a dicyandiamide-based curing agent, an imidazole-based curing agent, or the like is used. As the inorganic pigment, silica, titanium oxide, mica, or the like is appropriately used. The surface of the inorganic pigment may be subjected to a chemical treatment such as an aluminum-silica treatment, a silane coupling treatment, and a phosphate treatment.

The acrylic resin coating may be a thermoplastic acrylic resin coating or a thermosetting acrylic resin coating. In the thermoplastic acrylic resin paint, nitrocellulose may be used as a curing agent. Further, a vinyl resin may be mixed. The polyester-based resin paint uses an unsaturated polyester resin, a styrene monomer, paraffin, hydroquinone, and cobalt octoate as a main component, and a methyl ethyl ketone peroxide solution as a curing agent.

In the present invention, a paint is applied on the intermediate coat to form a coating film. The coating film formed by applying the paint is such that the coefficient of friction (static) of the coating film surface is 0.4 or less. It is adjusted to. When the coefficient of friction of the coating film exceeds 0.4, the magnetic shielding property and the peeling property of the coating film are deteriorated.
It is considered that the higher the coefficient of friction of the coating film, the greater the introduction of shear strain to the surface of the ground iron due to rubbing or the like due to the contact between steel sheets during winding forming, resulting in a decrease in magnetic permeability.

Adjustment of the coefficient of friction of the coating film surface can be achieved by changing the viscosity of the paint, winding tension, baking conditions, and the amount of inorganic pigment added. The viscosity of the paint can be changed by changing the compounding ratio of the epoxy resin and the curing agent or the compounding ratio of the diluted thinner. Thinner for dilution is
Those containing toluene as a main component and containing ethyl acetate, butyl acetate, amine acetate and the like are preferable.

The coefficient of friction and the basis weight of the coating film can be changed by a combination of the viscosity of the coating material and the application conditions. In order to keep the coefficient of friction of the coating film at 0.4 or less, the viscosity of the coating material should be No. 4 Ford cup measurement for 30 to 150 seconds, and the baking condition should be 180 ° C.
It is desirable to set it to 250 ° C. The basis weight of the coating film formed on the intermediate coating is limited to the range of ^{2 to} 8 g / m ² .

If the basis weight of the coating film is less than 2 g / m ² , coating unevenness is likely to occur, rusting occurs from a thin portion of the coating film, and the corrosion resistance is deteriorated. On the other hand, if the basis weight exceeds 8 g / m ² , the bending resistance deteriorates. For this reason, the basis weight of the coating film is ^{2 to} 8 g / m ^2.
Range. In addition, when the coefficient of friction is within the range of the present invention, the basis weight is a sufficient basis weight that does not cause deterioration of the magnetic shielding property even when the steel plates come into contact with each other.

[0034]

EXAMPLES In weight%, C: 0.035%, Si: 3.2%, Al:
A molten steel containing 5 ppm, Se: 0.02%, and Mn: 0.07% was formed into a slab by continuous casting, and then was subjected to hot rolling and cold rolling including intermediate annealing to obtain a steel sheet having a thickness of 0.23 mm. The steel sheet was subjected to decarburization annealing at 800 ° C., and thereafter, an annealing separator containing MgO as a main component was applied to the surface and finish annealing was performed at 1200 ° C. for 5 hours to obtain a grain-oriented electrical steel sheet. This steel plate has 2
A μm thick forsterite film was formed and B ₈ : 1.89
T, W _17/50 : had magnetic properties of 0.90 W / kg.

On the forsterite film on the surface of the grain-oriented electrical steel sheet, an intermediate film containing Cr oxide having the adhesion amount shown in Table 1 was formed by chromate treatment, and the coating material shown in Table 1 was applied by a roll coater. Then, baking was performed under the conditions shown in Table 1, and coating films having different basis weights and different friction coefficients shown in Table 1 were formed. After the coating was applied, it was wound into an 8-12 ton coil. In addition, the steel sheet which does not form an intermediate film | membrane was made into the comparative example.
Further, the coating films having different friction coefficients were obtained by changing the viscosity of the paint, the baking conditions, and the winding tension as shown in Table 1.

With respect to these coated grain-oriented electrical steel sheets,
The corrosion resistance, bending resistance, magnetic shielding property, and coating film peeling property were evaluated. In addition, five test pieces were collected for each test,
The test was performed. The test results are shown as average values and are shown in Table 1.

[0037]

[Table 1]

The corrosion resistance was evaluated by spraying a 5% hydrochloric acid solution (liquid temperature: 35 ± 1 ° C.) at a flow rate of 1 to 2 ml / hr on the surface of the coated steel sheet, and observing the occurrence of rust. The evaluation was based on the number of days required for occurrence. In the bending resistance test, a steel plate with a coating film was wound around round bars having different diameters, the maximum round bar diameter at which peeling of the coating film was recognized was determined, and the bending resistance was evaluated.

In the magnetic shielding test, a coated steel plate was wound around a round bar having a diameter of 20 mm seven times and formed, then divided into two samples, and the magnetic field of the permanent magnet 1 was applied to the sample 2 as shown in FIG.
And the strength of the magnetic field was measured using a measuring device consisting of a Gaussian measuring device 3, a conducting wire 4, and a meter 5. The magnetic shielding property was evaluated from the measured magnetic field strength. The strength of the magnetic field of the permanent magnet is 500 A / m.

The coating film peeling test was carried out using a steel sheet with each coating film at a thickness of 20 mm.
Visually observe the appearance of the coating film when wound around a φ round bar 7 times and formed and rewound. If no peeling is observed,
When the peeled area was 1% to 5%, the evaluation was Δ, and when the peeled area was 5% or more, the evaluation was ×. Each of the examples of the present invention is excellent in corrosion resistance, bending work resistance, coating film peeling resistance, and magnetic shielding properties, and has excellent performance as a magnetic shielding material.

In the comparative examples out of the range of the present invention, the magnetic shielding property and the peeling resistance of the film are deteriorated.

[0042]

According to the present invention, since a grain-oriented electrical steel sheet is used, the magnetic shielding properties are high, and even when subjected to severe forming processing, the peeling of the coating film and the decrease in magnetic permeability are small, and the workability is improved. In addition to being able to provide excellent magnetic shielding materials, it can also be used in high-temperature and high-humidity environments and has excellent corrosion resistance. Has the effect of

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the basis weight of a coating film and corrosion resistance.

FIG. 2 is a graph showing a relationship between a basis weight of a coating film and bending resistance.

FIG. 3 is a graph showing the relationship between the coefficient of friction of a coating film and the releasability of the coating film.

FIG. 4 is a graph showing a relationship between a coefficient of friction of a coating film and a magnetic shielding property.

FIG. 5 is an explanatory diagram showing a test method of a magnetic shielding property.

FIG. 6 is a graph showing the relationship between the adhesion amount of an intermediate film, corrosion resistance, and magnetic flux density.

FIG. 7 is a graph showing the relationship between the amount of an intermediate coating film and bending resistance, magnetic shielding property, and coating film peeling property.

[Description of Signs] 1 Permanent magnet 2 Sample 3 Gauss measuring instrument 4 Conductor 5 Meter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 22/00-22/86 H01F 1/16

Claims (2)

(57) [Claims] 1. A magnetic shielding material comprising a grain-oriented electrical steel sheet having a forsterite film, wherein at least one of Cu, Cr, Ni, Sn, and Zn is formed on the surface of the forsterite film.
With one metal or a compound of Cu, Cr, Ni, Sn, Zn
Forming a corrosion-resistant intermediate coating containing at least one compound of 5 to 100 mg / m ² , and further on the surface of the intermediate coating ,
Epoxy resin paint, acrylic resin paint and polyether
A magnetic shielding material excellent in corrosion resistance and workability, characterized in that a coating film having a friction coefficient of 0.4 or less is formed by applying one selected from stell-based resin paints to ² to 8 g / m ² . 2. A surface of a grain- oriented electrical steel sheet having a forsterite film , comprising at least one of Cu, Cr, Ni, Sn, and Zn.
One metal or compound of Cu, Cr, Ni, Sn, Zn
After treating with a solution containing at least one compound to form an intermediate coating having corrosion resistance of 5 to 100 mg / m ² , an epoxy having a viscosity of 30 to 150 seconds measured by a No. 4 Ford cup is applied to the surface of the intermediate coating. Applying and baking a resin-based paint, acrylic-based resin paint, or polyester-based resin paint such that the coefficient of friction is 0.4 or less and the basis weight of the coating film is ² to 8 g / m ^2. Manufacturing method of excellent magnetic shielding material.