JP4522688B2 - Magnetic substrate and laminate and method for producing the same - Google Patents

Description

  The present invention relates to a magnetic substrate including a novel silicon steel plate, a laminate, and a method for producing the same.

  In the global trend of energy savings including electric power, it is strongly desired to improve the efficiency of electrical equipment. In addition, from the viewpoint of miniaturization of electrical equipment, there is a growing demand for miniaturization of iron cores.

  Silicon steel sheets containing silicon in iron are widely used as the core material of electromagnetic transformers, inductors, motors, etc. used in such electrical equipment or power transmission / reception transformers. In recent years, silicon steel sheets tend to be thinned with the aim of reducing iron loss. However, the thinning of the steel sheet has a problem that, for example, in a laminated body such as a motor, the strength of the laminated body is deteriorated due to an increase in the caulking part accompanying the thinning, and the space factor is lowered. Moreover, since the magnetic properties are also deteriorated by mechanical processing strain such as punching, shearing, bending, etc., strain relief annealing is necessary to remove this strain and restore its original properties.

  If the silicon steel sheet is made thin in order to reduce the size and weight, the mechanical strength and surface portion of the steel sheet may be fragile. For this reason, in order to use a thin silicon steel plate, it is desirable that the resin be compounded. However, since silicon steel is usually subjected to strain relief annealing at a high temperature of 600 to 800 ° C., the silicon steel plate is used as a resin. In order to make it composite, it had to be performed after the annealing process. However, if an attempt is made to use a material that has undergone an annealing process, stress is applied at the time of compounding, strain is generated, and magnetic characteristics may be deteriorated.

  In addition, the composite with the resin after the annealing step has a problem that the adhesiveness is not sufficient, so that the punchability is insufficient, cracks are generated, and the yield is poor. Moreover, in the laminated body for motors, deterioration of the laminated body due to the increase of the caulking site and the space factor may be lowered.

  Under such circumstances, the present inventors have intensively studied to solve the above problems, and as a result, by performing heat treatment under specific heating conditions, a magnetic base material composed of an annealed silicon steel plate and a resin, and It has been found that a laminate can be obtained. Conventionally, an organic resin layer has been provided on the surface of a silicon steel plate, but this is an insulating coating and has been removed when used as an electromagnetic steel plate. In the present invention, a magnetic base material and laminated body, which are excellent in mechanical strength of the laminate and capable of strain relief annealing, are obtained by a magnetic base material in which a silicon steel plate and a heat resistant resin, particularly a thermoplastic heat resistant resin are integrated. A manufacturing method was developed.

The magnetic base material according to the present invention has a heat resistant resin and / or a precursor of a heat resistant resin applied to at least a part of one side or both sides of a silicon steel plate,
The amount of silicon contained in the silicon steel sheet is in the range of 0.5 to 7.5% by weight,
The thickness of the heat resistant resin and / or its precursor is not more than 1/2 of the total thickness.

The magnetic substrate is
It is preferable that the heat treatment is performed under the conditions of 180 ° C. ≦ Ta ≦ 1000 ° C. and 1000 ≦ Ta × t ≦ 260000 (° C./min); (Ta is the heat treatment temperature (° C.), and t is the heat treatment time (min) )).

  Examples of the heat resistant resin include thermoplastic resins. Examples of the heat resistant resin include polyimide, polyether-terketone, and polyethersulfone.

  The laminate according to the present invention is characterized in that two or more magnetic base materials described above are laminated. The laminate according to the present invention is characterized in that the magnetic base material or the laminate of the magnetic base material is punched out, and these are laminated and integrated. Furthermore, the laminate according to the present invention is characterized in that the magnetic substrate or the laminate of the magnetic substrate is punched out and laminated and integrated by caulking.

It is preferable that the laminate is heat-bonded and heat-treated under the conditions of 180 ° C. ≦ Ta ≦ 1000 ° C. and 1000 ≦ Ta × t ≦ 260000 (° C./min); ), T is the heat treatment time (minutes).

As a method for producing a magnetic substrate according to the present invention,
After applying a heat resistant resin and / or a precursor of a heat resistant resin to at least a part of one side or both sides of a silicon steel plate,
Laminate and punch the magnetic base material obtained as necessary,
Next, heat treatment is performed under the conditions of 180 ° C. ≦ Ta ≦ 1000 ° C. and 1000 ≦ Ta × t ≦ 260000 (° C./min); (Ta is heat treatment temperature (° C.), t is heat treatment time ( Min)).

  In the manufacturing method, it is preferable to perform heat treatment under pressure.

  By performing heat bonding and heat treatment under such conditions, mechanical strain is alleviated, and a laminated body with high core strength, high space factor, and excellent magnetic properties can be obtained by lamination integration. In addition, this effect is further improved by performing heat treatment under pressure.

  In the present invention, a magnetic base material and a magnetic laminate in which a heat-resistant resin is applied to a silicon steel plate, a laminate having high strength, a high space factor, and excellent magnetic properties can be mass-produced in a short time. It is possible to manufacture with good performance, and it is possible to reduce cracking at the time of punching and to improve the mold life.

Hereinafter, the magnetic substrate of the present invention and the production method thereof will be described in more detail.
(Magnetic substrate)
In the magnetic base material according to the present invention, a heat resistant resin and / or a precursor of a heat resistant resin is applied to at least a part of one side or both sides of a silicon steel plate.

Silicon steel plate The silicon steel plate used in the present invention may be one in which an inorganic insulating coating is usually applied to the surface of a commercially available steel plate, or it is obtained in the course of the manufacturing process of a silicon steel plate, and an inorganic insulation on the surface. The film may not be applied.

  As a silicon steel plate, the amount of silicon contained is 0.5 to 7.5% by weight, preferably 1.0 to 7% by weight, and more preferably 3 to 6.5% by weight.

  Si is an element useful for increasing the electrical resistance of steel and improving iron loss, and when included in the above range, it exhibits a sufficient iron loss improving effect. Further, if it is within this range, workability is high and cold rolling becomes easy.

  The composition of the silicon steel sheet used in the present invention is not particularly limited, and any conventionally known one is suitable.

  For example, a preferred composition range is as follows.

  Carbon (C) is basically preferably as little as possible and is preferably in the range of 0.10% by weight or less.

It is desirable that Mn is in the range of 2% by weight or less. Mn has an effect of preventing hot embrittlement, but when it exceeds 2% by weight, it induces deterioration of cold rollability. Therefore, it is necessary to make it 2% by weight or less.

  The silicon steel sheet may contain an inhibitor component. The inhibitor component is Se, S, Mn, Al, N, or the like used to form a dispersion precipitate called a so-called main inhibitor such as MnSe, MnS, or AlN. As the inhibitor component, Cu, Sn, Sb, Mo, Te, Bi and the like other than the above-described S, Se, Al are also advantageous, so they can be contained in small amounts. Each of these inhibitor components can be used alone or in combination.

  The method for producing the steel sheet is not particularly limited, and may be performed under conventionally known production conditions. That is, after hot rolling a silicon-containing steel slab, it is subjected to cold rolling twice or twice including intermediate annealing to obtain a final plate thickness, and after decarburization annealing, an annealing separator is applied to the steel plate surface. Then, secondary recrystallization annealing and purification annealing may be performed.

  The thickness of such a silicon steel sheet is appropriately selected according to the intended use, but it is usually sufficient if it is about 25 to 400 μm.

  In addition, usually, commercially available silicon steel plates have an inorganic insulating coating provided on the surface, but in the present invention, there is an inorganic insulating coating on the surface of the silicon steel plate. However, it can be sufficiently obtained as a magnetic substrate provided with the heat-resistant resin of the present invention. If necessary, the inorganic insulating coating may be removed by means such as etching.

Heat Resistant Resin In the present invention, the heat resistant resin is one having a weight reduction rate of 5% by weight or less due to thermal decomposition when subjected to a thermal history at 300 ° C. for 2 hours in a nitrogen atmosphere.

Furthermore, it is preferable to have one or more of the following characteristics.
(1) The tensile strength after passing through a heat history at 350 ° C. for 2 hours in a nitrogen atmosphere is 30 MPa or more,
(2) The glass transition temperature is 120 ° C to 250 ° C,
(3) The temperature at which the melt viscosity is 1000 Pa · s is 250 ° C. or more and 400 ° C. or less. (4) After the temperature is lowered from 400 ° C. to 120 ° C. at a constant rate of 0.5 ° C./min, crystals in the resin The heat of fusion by the object is 10 J / g or less.

  A thermoplastic resin is used as such a heat resistant resin.

Specific resins include polyimide resins, silicon-containing resins, ketone resins, polyamide resins, liquid crystal polymers, nitrile resins, thioether resins, polyester resins, arylate resins, sulfone resins, Examples thereof include imide resins and amide imide resins. Of these, it is preferable to use polyimide resin, (PI), polyetheretherketone resin (PEEK), or polyethersulfone (PES). PI, PEEK, and PES are suitable because they are high heat-resistant thermoplastic resins and have good adhesion to silicon steel sheets. Also, a composite of two or more of these resins may be used. These resins may be precursors. Examples of the precursor include a polyamic acid solution of a polyimide precursor.

As the thickness of such a heat resistant resin, the thickness of the layer formed from the heat resistant resin and / or its precursor is set to 1/2 or less of the total thickness of the base material. If it is the thickness of this range, sufficient intensity | strength as a base material can be hold | maintained.

  Further, as a lower limit, it is sufficient that a heat-resistant resin layer is provided as much as possible, and it may be 1/1000 or more of the previous thickness of the substrate.

Such a magnetic substrate is preferably subjected to a specific heat treatment as shown below.
(Manufacture of magnetic substrate)
The method for producing a magnetic base material according to the present invention is characterized in that a magnetic material base material provided with a heat-resistant resin on a silicon steel plate can be subjected to high-temperature strain relief annealing after punching out the base material.

  A heat resistant resin (or a precursor thereof) is applied to the silicon steel plate. The heat-resistant resin can be used by being dispersed or dissolved in a solvent as necessary. The solvent is not particularly limited as long as it can dissolve and disperse the heat-resistant resin and can be easily volatilized at a low temperature.

  The method for applying the heat resistant resin is not particularly limited, and a known method such as an impregnation method, a coating method, a spray spraying method, or the like is employed. In the case where a solvent is used, it is preferably carried out by performing a solvent removal treatment (heat drying at the boiling point of the solvent, drying under reduced pressure, air drying, etc.). Further, the precursor of the heat resistant resin may be changed to a heat resistant resin.

  The heat resistant resin may be provided on one side or both sides of the silicon steel plate. The heat resistant resin may be provided on the entire surface of the silicon steel plate or may be provided partially. For example, when sprayed, the heat resistant resin may be applied so as to be scattered. Even if it is partially provided, it is spread by heat or pressure during the heat treatment, so that the entire surface can be covered.

  Moreover, when making a precursor react, while heat-treating later, a silicon steel plate may be annealed and a heat resistant resin may be generated.

  A laminated body may be formed by stacking the necessary number of silicon steel plates on which the heat-resistant resin layer is formed in this manner. Further, the laminate may be punched out, or the laminate may be punched out and further caulked. Furthermore, a laminate may be stacked to form a new laminate.

  For the punching, known means such as press working can be used without limitation. In addition, it is possible to caulk the substrate / stacked body by caulking when punching.

  Moreover, when using the precursor of a heat resistant resin, it is also possible to form a laminated body simultaneously with formation of a heat resistant resin.

When performing heat bonding and heat treatment, the heat treatment conditions in the present invention are:
180 ℃ ≦ Ta ≦ 1000 ℃ and 1000 ≦ Ta × t ≦ 260000 (℃ ・ min)
It is a condition that satisfies.

  If it is this range, distortion removal, such as the adhesion | attachment between silicon steel plates and the cutting | disconnection which relieve | moderates the process distortion of the core for motors, can fully be performed by heat processing. Furthermore, the strength of the laminate (motor core) after heat treatment for strain removal can be kept high, and the heat resistant resin is not denatured.

The lower limit of Ta × t is not particularly limited as long as it can be subjected to strain relief annealing and the heat-resistant resin is not denatured. Xt
= 1000 (℃ ・ min) is chosen as the lower limit. The upper limit is preferably a low temperature and a long time, but the heat treatment time is preferably 24 hours or less in consideration of productivity, and is 24 hours at 180 ° C., and Ta × t = 260,000. In the present invention, when the magnetic base material in which a heat resistant resin is applied to a silicon steel sheet and the magnetic properties and strength of a laminate using the same are made compatible, sufficient effects can be obtained by heat bonding or heat treatment in this range. .

(Heat treatment method)
Although it does not restrict | limit especially as a heat processing method, A high frequency induction heating method, an infrared condensing heating method, a laser heating method, a hot-air heating method, a high temperature body contact heating method, a resistance overheating method, etc. are employ | adopted.

In the manufacturing method according to the present invention, the following elementary steps can be considered. The magnetic substrate of the present invention is produced by one or a combination of these.
(1) Step A: A heat-resistant resin precursor is applied to a silicon steel sheet, and the precursor is reacted to form a desired resin, followed by heat treatment.
(2) Step B: Lamination step, the resin of the magnetic base material may be melted and fused to a silicon steel plate of another magnetic base material. In any state, a heat-resistant resin exists between the silicon steel plates, and the laminate indicates such a state.
(3) Step C: Like the step B, it is a lamination step, in which the resins imparted to the silicon steel plate of the magnetic base material can be melted and fused to be integrated more firmly.

  Process B and process C are usually performed simultaneously by hot pressing or the like.

Specifically, there are combination methods represented by the following. The above elementary process may be performed at the same time, for example,
(I) A method in which the heat treatment is performed after a laminated body is formed by heat fusion after stacking magnetic base materials that have not been heat-treated. (Process B and process C are performed simultaneously)
(Ii) A method of forming a laminate by heat fusion after stacking heat-treated magnetic substrates. (Process B and process C are performed simultaneously)
(Iii) A method in which a heat-resistant resin precursor is used, and the precursor is stacked on a magnetic base material that has not been subjected to heat treatment, and then a laminate is formed simultaneously with the formation of the heat-resistant resin, followed by heat treatment. (Process B and process C are performed simultaneously)
(Iv) A method in which a precursor of a heat resistant resin is used, and a laminate is formed simultaneously with the formation of the heat resistant resin after the precursor is stacked on a heat-treated magnetic base material. (Steps B and C are performed at the same time) (v) A method in which a heat-resistant resin or a precursor of a heat-resistant resin is stacked, and then heat-treated and then laminated and bonded.

  When creating a laminated body, a laminated body may be formed by stacking a required number of single-layer ones, or a laminated body may be stacked and formed as a laminated body. Moreover, when using the precursor of a heat resistant resin, it is also possible to form a laminated body simultaneously with formation of a heat resistant resin.

A laminate having an appropriate number of layers is used depending on the application. The layers of the laminate may be the same type of magnetic substrate or different types of magnetic substrates.
(Pressurized heat treatment method)
The present invention is characterized in that a resin is applied to one side or both sides of a silicon steel plate by some method and then heat-treated to improve the magnetic properties by applying pressure.

The pressure heat treatment is usually performed at a temperature of 180 to 1000 ° C. under a pressure of 0.01 to 500 MPa. The process may be performed once or divided into a plurality of times. Different conditions may be used when performing multiple times.

  As described above, according to the present invention, a novel magnetic substrate made of a silicon steel plate and a heat resistant resin can be obtained. Such a magnetic substrate has improved mechanical strength as a laminate, and can obtain excellent magnetic properties by reducing residual stress by heat treatment for strain relief. Furthermore, it is excellent in productivity, and can be manufactured with high productivity in a very short time. Such magnetic substrates and laminates are easy to manufacture and can be manufactured continuously, so that they are suitable for mass production and are not restricted by complicated shapes such as for motors and transformers.

EXAMPLES The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to these examples.
(Examples 1-6, Comparative Examples 1 and 2)
For a motor from a magnetic base material (single side) in which a resin layer of various heat-resistant adhesive resins is applied to a silicon steel plate containing about 3% Si and having a thickness of about 150 μm, as shown below, with a resin layer of various heat-resistant adhesive resins. A stack of 320 magnetic substrates punched into a stator shape by pressing was stacked to produce a stator laminate having a height of about 5 cm and a diameter of 10 cm, and an impact resistance test in accordance with JIS C0041 was performed. As the stator laminate, one obtained by heat bonding, caulking + heat bonding, and fixing and laminating and integrating by a conventional caulking method was used.

  The laminates of Examples 1, 2 and 4 were coated with a polyamic acid varnish (resin content 18%) on a silicon steel plate with a gravure coater, and Example 3 was spray coated (partial mist). Shape) A magnetic base material was formed so as to have an average thickness of 3 μm by drying with hot air, and punched and laminated into a stator shape by general-purpose pressing.

  Examples 2 and 3 were caulked and then caulked.

In Examples 1 to 4, the obtained laminate was heated at 270 ° C. for 10 minutes to immobilize and adhere the laminate, and subsequently heat treated at 350 ° C. for 4 hours in order to reduce punching distortion.

The silicon steel plate used in Example 4 was obtained by removing the surface inorganic layer by etching.

In Example 5, varnish (PES weight 30%) dissolved in a DMAc solvent was applied to the surface of a silicon steel plate and dried with hot air, heated at 280 ° C. for 30 minutes, and the laminate was fixed and adhered. A laminate was prepared in the same manner as above, and this was heat-treated at 350 ° C. for 4 hours.

  For the liquid crystal polymer of Example 6, after applying a molten resin to the surface of the silicon steel plate, a laminate was prepared in the same manner as in Example 2 and heat treated at 350 ° C. for 4 hours.

  In Comparative Examples 1 and 2, a resin layer was formed by applying a low-viscosity epoxy or acrylic adhesive to the surface of a silicon steel plate and drying it with hot air. The obtained magnetic base material was punched and caulked in the same manner as in Examples 2 and 3, and subjected to heat treatment for removing strain at 350 ° C. for 4 hours.

  In Comparative Example 3, the silicon steel plates were laminated as they were, and without being subjected to heat treatment for bonding, they were punched and caulked in the same manner as in Examples 2 and 3, and heat treatment for strain relief was performed at 350 ° C. for 4 hours. It was.

  The results are shown in Table 1.

As is clear from Table 1, in the conventional caulking of Comparative Example 3, some peeling is seen on the end face of the laminate, but the laminate of the thermoplastic polyimide resin of the present invention, the thermoplastic polyethersulfone, and the melt type liquid crystal polymer. However, as in the case before the test, no deterioration was observed in the laminate. In addition, in a stator-shaped laminate using a magnetic base material provided with a resin having low heat resistance such as epoxy and acrylic, the resin deteriorates during heat treatment for removing strain at 350 ° C. for about 4 hours. The strength of the laminate was the same as that of the caulking method alone.
(Example 7, Comparative Example 4) Effect of heat treatment for strain relief of laminated body In Example 7, a varnish of polyamic acid (resin content: 18%) was coated on a silicon steel plate with a gravure coater to an average thickness of 3 μm. Seven pieces of ring-shaped (outer diameter 28 mm, inner diameter 20 mm) punched out from a magnetic base material formed with thermoplastic polyimide resin were laminated with a general-purpose press, and this was laminated and integrated at 270 ° C for 30 minutes. A toroidal laminate was prepared.

  The comparative example 4 produced the toroidal laminated body similarly using the acrylic resin varnish instead of the polyamic acid varnish.

The obtained laminate was examined for evaluation of magnetic properties and shape (visual observation). The magnetic characteristics were obtained by using an AC BH analyzer (manufactured by Iwatatsu Electronics Co., Ltd.) for the iron loss value under the conditions of frequency f = 1 kHz and maximum magnetic flux density Bm = 1.0 T (magnetic flux sin wave).

  The results are shown in Table 2.

As shown in Table 2, the laminate to which the thermoplastic polyimide was applied had almost no deformation even at 400 ° C., and the effect of removing distortion of the magnetic properties (reduction of about 15%) was obtained. On the other hand, in the laminate of acrylic resin as seen in the comparative example, the outer dimensions and height dimensions were deformed by about 0.7% at 300 ° C. At 400 ℃, carbides were generated from the end face, the magnetic properties deteriorated significantly (about 22%), and the dimensions were deformed by more than 3% (height).

Claims (10)

A heat resistant resin and / or a precursor of a heat resistant resin is applied to at least a part of one side or both sides of a silicon steel plate,
The amount of silicon contained in the silicon steel sheet is in the range of 0.5 to 7.5% by weight,
( i) the heat resistant resin is at least one thermoplastic resin selected from the group consisting of polyimide, polyetheretherketone, polyethersulfone, and liquid crystal polymer;
(ii) the thickness of the heat resistant resin and / or its precursor is 1/2 or less of the total thickness,
(iii) 180 ° C. ≦ Ta ≦ 1000 ° C., and a magnetic base material that is heat-treated under the conditions satisfying 1000 ≦ Ta × t ≦ 260000 (° C./min);
(Ta is a heat treatment temperature (° C.), and t is a heat treatment time (minute)).   A laminate of magnetic substrates, comprising two or more magnetic substrates according to claim 1 laminated.   A laminate comprising the magnetic substrate according to claim 1 or a laminate of magnetic substrates, which is formed by stacking and integrating them.   A laminate comprising the magnetic substrate according to claim 1 or a laminate of the magnetic substrate, wherein the laminate is integrated by stamping. Heat resistance comprising at least one thermoplastic resin selected from the group consisting of polyimide, polyetheretherketone, polyethersulfone and liquid crystal polymer on at least a part of one or both sides of a silicon steel sheet having a silicon content of 0.5 to 7.5% by weight After the resin and / or heat-resistant resin precursor is applied at a thickness of 1/2 or less of the total thickness,
Next, a method for producing a magnetic base material, characterized in that heat treatment is performed under conditions satisfying 180 ° C. ≦ Ta ≦ 1000 ° C. and 1000 ≦ Ta × t ≦ 260000 (° C./min); (Ta is a heat treatment temperature (° C.)) , T is the heat treatment time (minutes).   The manufacturing method according to claim 5, wherein the heat treatment is performed in a range of 270 to 400 ° C.   The method for producing a magnetic substrate according to claim 5 or 6, wherein heat treatment is performed under pressure.   The manufacturing method according to claim 7, wherein the pressurizing treatment is performed under a pressure of 0.01 to 500 MPa.   The method for producing a magnetic base material according to any one of claims 5 to 8, wherein the heat-resistant resin and / or the silicon steel plate provided with the heat-resistant resin precursor is laminated, and then punched and heat-treated.   The method for producing a magnetic substrate according to any one of claims 5 to 8, wherein a heat-resistant resin and / or a silicon steel plate provided with a precursor of the heat-resistant resin is laminated, punched, caulked and then heat-treated. .