HK1187083B - Electromagnetic steel sheet and process for production thereof - Google Patents

Description

Electromagnetic steel sheet and method for producing same

Technical Field

The present invention relates to an electrical steel sheet used as, for example, an iron core material of an electrical apparatus and a method for manufacturing the same, and more particularly, to an electrical steel sheet having an insulating coating film which has good insulation properties, particularly good corrosion resistance and adhesion under a wet environment, and which does not contain chromic acid, and a method for manufacturing the same. The present application is based on and claims priority from japanese patent application No. 2010-244030, filed on 10/29/2010, the contents of which are incorporated herein by reference.

Background

In manufacturing a motor or a transformer, a strip-shaped electromagnetic steel sheet is first punched into a predetermined shape, and then the strip-shaped electromagnetic steel sheets are laminated and adhered to each other to produce an iron core. Then, after winding the copper wire into a tooth (tooth) or the like, a varnish is impregnated or a powder coating is sprayed. Then, a terminal for copper wire connection, a flange, a bearing, and the like are attached and fixed to the case.

In the manufacturing process of such an iron core, the process of punching the electrical steel sheet into a predetermined shape often takes a long time because of the large restrictions on equipment such as punching.

Therefore, in order to efficiently perform the punching step, a strip-shaped electromagnetic steel sheet is prepared in advance, or a copper wire winding step after punching is performed in a lump, thereby achieving high efficiency.

When storing a strip-shaped electrical steel sheet, a storage is generally used to prevent rust, but in order to efficiently perform a punching process, the electrical steel sheet is often taken out from the storage in advance, and in this case, special attention needs to be paid to rust.

In recent years, cost reduction has been widely performed by moving the processing base of iron cores to china or south-east asia. In such countries, factories are often installed in a more humid environment than in japan, and corrosion resistance in a more humid environment than in japan is required.

Generally, an electrical steel sheet used for an iron core of an electrical apparatus is coated with an insulating coating film on its surface to reduce eddy current loss, and the insulating coating film is required to have coating film properties such as corrosion resistance, adhesion, punching property, and heat resistance in addition to insulation properties.

The insulating coating film generally contains a mixture of an inorganic acid salt such as chromate or phosphate and an organic resin as main components. In recent years, an insulating coating film containing no chromium is demanded from the viewpoint of environment.

With the progress of high efficiency of the manufacturing process of iron cores for electrical equipment, the insulating coating of an electrical steel sheet is required to have corrosion resistance higher than that, and particularly, to have improved corrosion resistance in a wet environment.

That is, the conventional insulating coating for an electrical steel sheet does not have sufficient corrosion resistance to the extent that rust formation in the storage container can be suppressed before the punching step, and in contrast, in recent years, corrosion resistance that does not cause rust formation even in a wet environment has been demanded.

Further, although the corrosion resistance can be improved by applying the insulating coating film thickly, there is a problem that the space factor is lowered or the adhesion is lowered.

Further, in an electrical steel sheet having an insulating coating film made of a coating material mainly composed of a fluororesin on the surface, there are problems that the cost is increased and varnish after punching does not adhere.

Documents of the prior art

Patent document

Patent document 1: japanese examined patent publication (Kokoku) No. 50-15016

Patent document 2: japanese laid-open patent publication No. H03-36284

Patent document 3: japanese examined patent publication No. 49-19078

Patent document 4: japanese laid-open patent publication No. H06-330338

Patent document 5: japanese laid-open patent publication No. H09-323066

Patent document 6: japanese laid-open patent publication No. 2002-309379

Patent document 7: japanese laid-open patent publication No. H05-98207

Patent document 8: japanese laid-open patent publication No. H07-41913

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrical steel sheet having further excellent corrosion resistance in a wet environment and excellent film properties, and a method for manufacturing the same.

Means for solving the problems

The gist of the present invention is as follows.

(1) An electromagnetic steel sheet characterized by: the surface of the steel sheet is covered with an insulating coating film mixed with:

a mixture comprising 100 parts by mass of a metal phosphate and 1 to 50 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 [ mu ] m: 100 parts by mass, and

copolymers of fluoroolefins and ethylenically unsaturated compounds on a solids basis: 0.5 to 10 parts by mass.

(2) An electromagnetic steel sheet characterized by: the surface of the steel sheet is covered with an insulating coating film mixed with:

a mixture comprising 100 parts by mass of colloidal silica and 40 to 400 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 [ mu ] m: 100 parts by mass, and

copolymers of fluoroolefins and ethylenically unsaturated compounds on a solids basis: 0.5 to 10 parts by mass.

(3) A method for manufacturing an electrical steel sheet, comprising the steps of:

mixing 1 to 50 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 μm, in terms of solid content, with respect to 100 parts by mass of a metal phosphate;

a step of preparing a treatment liquid in which a copolymer of a fluoroolefin and an ethylenically unsaturated compound is mixed in an amount of 0.5 to 10 parts by mass in terms of solid content per 100 parts by mass of the solid content of the mixture of the metal phosphate and the organic resin;

applying the prepared treatment liquid to the surface of a steel sheet; and

and a step of baking and drying the steel sheet coated with the treatment liquid at an arrival temperature of 200 to 380 ℃ for 15 to 60 seconds.

(4) A method for manufacturing an electrical steel sheet, comprising the steps of:

mixing 40 to 400 parts by mass of an organic resin containing a mixture or a copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 μm in terms of solid content, based on 100 parts by mass of colloidal silica;

a step of preparing a treatment liquid in which a copolymer of a fluoroolefin and an ethylenically unsaturated compound is mixed in an amount of 0.5 to 10 parts by mass in terms of solid content per 100 parts by mass of the solid content of the mixture of the colloidal silica and the organic resin;

applying the prepared treatment liquid to the surface of a steel sheet; and

and a step of baking and drying the steel sheet coated with the treatment liquid at an arrival temperature of 200 to 300 ℃ for 15 to 60 seconds.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an electrical steel sheet coated with an insulating coating film having good corrosion resistance in a wet environment and maintaining coating film properties required for the electrical steel sheet, such as adhesion, space factor, and punching properties, can be obtained.

Detailed Description

The following describes specific embodiments for carrying out the present invention.

First, the steel sheet used in the present embodiment preferably contains Si: 0.1 mass% or more, Al: 0.05 mass% or more of a steel sheet for a non-oriented electrical steel sheet. Si is preferably less than 4.0 mass% because Si increases the electrical resistance and improves the magnetic properties, but increases brittleness and decreases the rolling properties. Similarly, if the content of Al is increased, the magnetic properties are improved, but the rolling property is lowered, so that it is preferably less than 3.0 mass%. In the steel sheet used in the present embodiment, Mn, Sn, Cr, and P may be contained in a range of 0.01 to 1.0 mass% in addition to Si and Al. Furthermore, other S, N, C elements typically may be present, preferably in amounts of less than 100ppm, preferably less than 20 ppm.

In this embodiment, a steel sheet having the above composition is produced by heating a slab to 1000 to 1250 ℃, hot rolling the slab, winding the hot rolled slab into a coil, annealing the hot rolled slab at 800 to 1050 ℃ as necessary, cold rolling the hot rolled slab to 0.15 to 0.5mm, and annealing the hot rolled slab at 750 to 1100 ℃.

Before the treatment liquid described later is applied to the surface of the steel sheet on which the insulating coating film is to be formed, any pretreatment such as degreasing treatment with an alkali or the like and pickling treatment with hydrochloric acid, sulfuric acid, phosphoric acid or the like may be performed, or the surface state after the final annealing may be maintained without performing the pretreatment.

In the steel sheet used in the present embodiment, the surface roughness is preferably finished so that the arithmetic mean deviation (Ra) of the roughness in the rolling direction and the direction perpendicular to the rolling direction is 1.0 μm or less, and more preferably 0.1 to 0.5 μm.

Next, the insulating coating film formed on the surface of the steel sheet will be described. The insulating coating film contains a phosphate metal salt or colloidal silica as a main component.

The metal phosphate is a substance obtained by drying an aqueous solution containing phosphoric acid and metal ions as main components to obtain a solid, and the kind of phosphoric acid is not particularly limited, but orthophosphoric acid, metaphosphoric acid, polyphosphoric acid, and the like are preferable.

Further, as the kind of the metal ion, ions such as Li, Al, Mg, Ca, Sr, Ti, Ni, Mn, and Co are preferable, and particularly, ions of Al, Ca, Mn, and Ni are preferable. When the metal phosphate solution is prepared, for example, an oxide, a carbonate, or a hydroxide of metal ions is preferably mixed with orthophosphoric acid.

The metal phosphate may be used alone or in combination of 2 or more. In addition, only the metal phosphate may be used, or an additive such as phosphonic acid or boric acid may be added.

On the other hand, the colloidal silica preferably has an average particle diameter of 5nm to 40nm and a Na content of 0.5 mass% or less, and more preferably a Na content of 0.01 mass% to 0.3 mass%.

The average particle size of the colloidal silica used in the present embodiment is a number average particle size, and is measured by a nitrogen adsorption method.

These metal phosphates or colloidal silica, and an organic resin composed of a mixture or copolymer of 1 or 2 or more selected from acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 μm, which will be described below, are thinly formed on the surface of the steel sheet as an insulating coating film. The thickness of the insulating coating film is preferably about 0.3 to 3.0. mu.m, and more preferably 0.5 to 1.5. mu.m.

As the acrylic resin, the epoxy resin, and the polyester resin used in the present embodiment, a generally commercially available organic resin emulsion may be used. Among the acrylic resins, as usual monomers, particularly preferred are: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-dodecyl acrylate, and the like. In addition, acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid are preferably copolymerized as the monomer having a functional group. Further, it is preferable that the monomer having a hydroxyl group is copolymerized with 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxyethyl- (meth) allyl ether, or the like.

In the case of the epoxy resin, for example, a product obtained by reacting a carboxylic anhydride with an amino-modified epoxy resin is exemplified, and specifically, bisphenol a-diglycidyl ether, a caprolactone ring-opening adduct of bisphenol a-diglycidyl ether, bisphenol F-diglycidyl ether, bisphenol S-diglycidyl ether, novolak glycidyl ether, dimer acid glycidyl ether, and the like are preferable. Here, as the modified amino group, isopropanolamine, monopropanolamine, monobutanolamine, monoethanolamine, diethylenetriamine, ethylenediamine, butanamine, propylamine, isophoronediamine, tetrahydrofurfuryl amine, xylylenediamine, hexylamine, nonanamine, triethylenetetramine, tetramethylenepentamine, diaminodiphenylsulfone, and the like are preferable. The carboxylic anhydride is preferably obtained by reacting succinic anhydride, itaconic anhydride, maleic anhydride, citraconic anhydride, phthalic anhydride, trimellitic anhydride, or the like.

Preferred examples of the polyester resin include those obtained by reacting a dicarboxylic acid such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, fumaric acid, maleic anhydride, itaconic acid, or citraconic acid with a diol such as ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, triethylene glycol, dipropylene glycol, or polyethylene glycol. Further, these polyester resins may be graft-polymerized with acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, methacrylic anhydride, or the like.

The organic resin emulsion may be a mixture of 1 or 2 or more selected from the group consisting of the acrylic resin, the epoxy resin and the polyester resin, or may be a copolymer of these resins. The average particle diameter of the organic resin emulsion is in the range of 0.05 to 0.50. mu.m. The average particle diameter of the organic resin emulsion is a number average particle diameter and is measured by a laser diffraction method. This is because the particles tend to aggregate in the treatment solution when the average particle size is 0.05 μm or less, and the uniformity of the insulating coating film may be reduced, and the solution stability may be reduced when the average particle size exceeds 0.50 μm. If the stability of the solution is deteriorated, aggregates are generated in the solution, and the solution may be treated to block pipes or pumps. In addition, if the aggregate enters the insulating coating film, defects may occur in the insulating coating film. The average particle diameter of the organic resin emulsion is more preferably in the range of 0.1 to 0.3. mu.m.

The mixing ratio of the metal phosphate and the organic resin containing a mixture or copolymer of 1 or 2 or more selected from among the acrylic resin, the epoxy resin and the polyester resin is set to 1 to 50 parts by mass based on 100 parts by mass of the metal phosphate. This is because: when the mixing ratio of the organic resin is less than 1 part by mass, the concentration of the resin is too small to easily aggregate, thereby deteriorating the stability of the solution, and when it exceeds 50 parts by mass, the heat resistance may be poor.

The mixing ratio of the colloidal silica and the organic resin is set to 40 to 400 parts by mass of the organic resin per 100 parts by mass of the colloidal silica. This is because: when the mixing ratio of the organic resin is less than 40 parts by mass, the film forming property is poor, and the insulating coating film may be pulverized, and when it exceeds 400 parts by mass, the heat resistance may be poor.

In the present embodiment, in addition to the above-described components, a copolymer of a fluoroolefin and an ethylenically unsaturated compound is contained in the insulating coating film.

The copolymer of a fluoroolefin and an ethylenically unsaturated compound used in the present embodiment is obtained by copolymerizing a monomer, an oligomer, or a low-molecular polymer having a radical polymerizable unsaturated group with a fluoroolefin. Here, the term "fluoroolefin" refers to a compound having an unsaturated hydrocarbon structure in which fluorine atoms are directly bonded to the carbon skeleton of an olefin, and at least 1 of the groups bonded to the carbon having an unsaturated bond is a fluorine atom. Specific examples thereof include tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride and fluorotrichloroethylene. In the present embodiment, 1 or 2 or more of them can be used.

The ethylenically unsaturated compound is a substance having a vinyl group in its structure and capable of forming a copolymer with a fluoroolefin, and is generally called a vinyl ether, and is a monomer, an oligomer or a low-molecular polymer having various functional groups. Examples of the monomer include styrene, vinyl acetate, polypropylene glycol acrylate, methoxy polyethylene methacrylate, vinyl alkyl ether, vinyl alkylene ether, isoprene, and acrylonitrile. These monomers may be used, and oligomers or low-molecular polymers having the same structure may be used. In the present embodiment, a monomer, oligomer, or low-molecular polymer having various functional groups introduced therein may be used. Examples of such functional groups include alkyl groups, hydroxy-substituted alkylene groups, phenyl groups, benzyl groups, cyclic aliphatic groups, acetyl groups, and crosslinkable reactive groups such as carboxyl groups, hydroxyl groups, epoxy groups, and amino groups. Examples of the alkyl group and the alkylene group include a straight-chain alkyl group having 1 to 10 carbon atoms (C) connected in a row, and examples of the alkylene group include a straight-chain hydroxy alkylene group having 1 to 14C atoms connected in a row and a hydroxy group at the end. In addition, the functional group in the present embodiment is a functional group not including a functional group having a fluorine group or another fluorine atom.

Further, as the ethylenically unsaturated compound, a compound obtained by reacting glycidyl methacrylate, hydroxymethyl acrylate, N-dimethylaminoethyl methacrylate, diacetylacrylamide, butadiene, chloroprene or the like with a monomer, an oligomer or a low-molecular polymer having these functional groups can be used.

These fluoroolefins obtained by copolymerizing ethylenically unsaturated compounds have a fluorine atom-containing moiety and a fluorine atom-free moiety. Therefore, heat resistance and water resistance are maintained by the fluorine atom-containing moiety, while adhesion to the substrate and flexibility are maintained by the functional group introduced into the fluorine atom-free moiety. Further, by not including a functional group having a fluorine group or another fluorine atom in a part of the ethylenically unsaturated compound, an insulating coating film having improved dispersibility and excellent uniformity can be obtained.

These copolymers of the fluoroolefin and the ethylenically unsaturated compound may be used alone, or may be obtained by mixing 2 or more kinds of copolymers having different functional groups, copolymers having different molecular weights, or the like.

The particle size of the copolymer of the fluoroolefin and the ethylenically unsaturated compound is not particularly limited, but is preferably in the range of 0.05 to 0.50. mu.m, more preferably in the range of 0.05 to 0.20. mu.m. If the particle size is less than 0.05. mu.m, the particles tend to aggregate in the solution, and the stability of the solution may deteriorate. As described above, if the stability of the solution is deteriorated, aggregates are generated in the solution, and the piping or the pump may be clogged when the solution is treated. In addition, if the aggregate enters the insulating coating film, defects may occur in the insulating coating film. If the thickness exceeds 0.50 μm, the insulating coating film may be easily peeled off and pulverized. Further, when the particle size is 0.20 μm or less, a beautiful appearance can be easily obtained.

Next, the mixing ratio of the copolymer of the fluoroolefin and the ethylenically unsaturated compound to the mixture of the metal phosphate and the organic resin is set to 0.5 to 10 parts by mass in terms of solid content, relative to 100 parts by mass of the solid content of the mixture. This is because: when the mixing ratio of the copolymer is less than 0.5 parts by mass, the effect of improving the corrosion resistance may not be sufficiently exhibited, and when it exceeds 10 parts by mass, the stability of the solution may be deteriorated, and the workability may be lowered.

The mixing ratio of the copolymer of a fluoroolefin and an ethylenically unsaturated compound to the mixture of colloidal silica and the organic resin is also set to 0.5 to 10 parts by mass in terms of solid content, relative to 100 parts by mass of the solid content of the mixture. This is because: when the mixing ratio of the copolymer is less than 0.5 parts by mass, the effect of improving the corrosion resistance cannot be sufficiently exhibited, and when it exceeds 10 parts by mass, the stability of the solution is deteriorated.

The insulating coating film may contain components other than a mixture of the metal phosphate or colloidal silica and the organic resin, and a copolymer of the fluoroolefin and the ethylenically unsaturated compound. For example, inorganic compounds such as carbonates, hydroxides, oxides, titanates, and tungstates, or organic low molecular weight compounds such as polyols, cellosolves, carboxylic acids, ethers, and esters may be mixed as additives.

Next, when the treatment liquid containing the components described above is applied to the surface of the steel sheet, the application method is not particularly limited, and a roll coater method, a spray method, a dip method, or other application methods may be used.

In the case of a heating method using a dry baking treatment liquid, a general radiation furnace or hot blast furnace may be used, and an induction heating method, a high-frequency heating method, or the like may be used.

The drying conditions are, for example, in the range of 200 ℃ to 380 ℃ and the baking time is suitably 15 seconds to 60 seconds. In the case of the insulating coating film containing a metal phosphate, the temperature is more preferably in the range of 260 to 330 ℃. On the other hand, in the case of an insulating coating film containing colloidal silica, 200 to 300 ℃ is suitable, and 240 to 280 ℃ is more preferred.

Further, an additive such as a surfactant may be added to the treatment liquid. As the surfactant, an aliphatic polyoxyalkylene ether surfactant is suitable, and other gloss agents, preservatives, antioxidants and the like may be added.

The copolymer is dispersed in the insulating coating film composed of the copolymer of the fluoroolefin and the ethylenically unsaturated compound and the mixture of the metal phosphate or the colloidal silica and the specific organic resin. The dispersed copolymer of the fluoroolefin and the ethylenically unsaturated compound is concentrated in the vicinity of the surface layer of the insulating coating film, thereby substantially optimizing the surface tension of the insulating coating film. As a result, it is considered that the corrosion resistance under a wet environment is improved while the adhesion force is maintained.

Examples

Next, experiments performed by the present inventors will be described. The conditions and the like of these experiments are examples employed for confirming the feasibility and the effects of the present invention, and the present invention is not limited to these examples.

First, a composition containing Si: 2.0 mass%, Al: 0.3 mass%, Mn: 0.3 mass% and a plate thickness of 0.35mm, and a surface roughness of 0.44 μm in terms of Ra (arithmetic mean deviation of roughness). The surface roughness of the steel sheet was measured using a commercially available surface roughness measuring apparatus according to JIS method (JISB 0601).

Next, the mixed liquids of Nos. 1 to 15 shown in Table 1 below were prepared.

TABLE 1

No.	Liquid name of adhesive	Organic resin	Mass fraction of resin	Other additives
					1	Aluminium phosphate	Acrylic resin 1	20
2	Nickel phosphate	Acrylic resin 1	15
					3	Manganese phosphate	Epoxy resin 1	8	Phosphonic acid 1.5
4	Aluminium phosphate	Polyester resin	40
					5	Colloidal silicon dioxide	Acrylic resin 1	100
6	Colloidal silicon dioxide	Epoxy resin 1	80
					7	Aluminium phosphate	Acrylic resin 2	30
8	Aluminium phosphate	Epoxy resin 2	30
					9	Aluminium phosphate	Acrylic resin 1	0.5
10	Calcium phosphate	Polyester resin	60
					11	Aluminium phosphate	Aqueous polyurethane	30
12	Colloidal silicon dioxide	Epoxy resin 2	30
					13	Colloidal silicon dioxide	Acrylic resin 1	30
14	Colloidal silicon dioxide	Acrylic resin 1	450
					15	Magnesium chromate	Acrylic resin 1	30

Orthophosphoric acid, Al (OH) were mixed and stirred as a metal phosphate₃The metal phosphate treatment solution was prepared by mixing a metal hydroxide, an oxide or a carbonate, and made into a 40 mass% aqueous solution. As a reference example, a 40 mass% magnesium chromate aqueous solution was also prepared.

As the colloidal silica, commercially available silica having an average particle diameter of 15nm and a surface modified with aluminum at a concentration of 30% by mass was used.

As for the organic resin, 6 kinds of organic resins shown below were prepared as latex solutions having a concentration of 30 mass%, respectively. Further, a viscosity adjusting agent and a surfactant were added in an appropriate amount to prepare a mixture shown in Table 1.

(1) Acrylic resin 1: an acrylic resin obtained by copolymerizing 30 mass% of methyl methacrylate, 10 mass% of 2-hydroxyethyl methacrylate, 30 mass% of n-butyl acrylate, 10 mass% of a styrene monomer, and 20 mass% of isobutyl acrylate

(2) Acrylic resin 2: an acrylic resin obtained by copolymerizing 45 mass% of methyl acrylate, 30 mass% of a styrene monomer, 20 mass% of isobutyl acrylate, and 15 mass% of maleic acid

(3) Epoxy resin 1: carboxyl modified epoxy resin obtained by modifying bisphenol A with triethanolamine and then reacting with succinic anhydride

(4) Epoxy resin 2: the epoxy resin is self-emulsified by mixing an ethylene-propylene block polymer with a phenol novolac epoxy resin and adding nonylphenyl ether ethylene oxide

(5) Polyester resin: a carboxyl group-containing polyester resin obtained by copolymerizing 35 mass% of dimethyl terephthalate and 35 mass% of neopentyl glycol and graft-polymerizing 15 mass% of fumaric acid and 15 mass% of trimellitic anhydride

(6) Aqueous polyurethane: aqueous polyurethanes synthesized in a known manner from hexamethylene diisocyanate and polyethylene glycol

The average particle diameters of the acrylic resin 1 and the acrylic resin 2 were 0.25 μm and 0.64 μm, respectively. The average particle diameters of the epoxy resin 1 and the epoxy resin 2 were 0.33 μm and 0.76 μm, respectively. The average particle size of the polyester resin was 0.35 μm, and the average particle size of the aqueous polyurethane was 0.12. mu.m. The resin parts by mass shown in table 1 are parts by mass in terms of solid content.

In the mixed liquid No.3, 1.5 parts by mass of phosphonic acid was added as a coating agent to 100 parts by mass of manganese phosphate.

Next, a treatment liquid in which a predetermined amount of the copolymer of a fluoroolefin and an ethylenically unsaturated compound or the fluororesin shown in table 2 below was added to the mixed liquid shown in table 1, and a treatment liquid to which nothing was added were prepared. The amount of the fluororesin (parts by mass) shown in table 2 is parts by mass in terms of solid content.

TABLE 2

Copolymer 1 shown in table 2 was obtained by copolymerizing tetrafluoroethylene and linear alkyl vinyl ether having 6 carbon atoms, and copolymer 2 was obtained by copolymerizing tetrafluoroethylene and methyl vinyl ether. The copolymer 3 is obtained by copolymerizing chlorotrifluoroethylene, propylene alkyl vinyl ether and hydroxyhexyl vinyl ether, and then substituting a hydroxyl group with a carboxyl group. Copolymer 4 is obtained by copolymerizing chlorotrifluoroethylene and hydroxydodecyl vinyl ether, respectively, by known methods. As a known method of copolymerization, for example, the method disclosed in Japanese patent No. 3117511 is preferable, and as a method of substitution with a carboxyl group, the method disclosed in Japanese patent publication No. 58-136605 can be used. The fluororesin 1 is polytetrafluoroethylene, and the fluororesin 2 is polyvinylidene fluoride. Further, the fluororesin 3 is perfluoroalkoxy paraffin.

The coating of the treatment liquid was carried out by using a roll coater system, and the thickness of the insulating coating film was adjusted to about 0.8 μm by adjusting the roll draft and the like. Drying was performed using a radiation furnace, and the furnace temperature setting was adjusted to obtain the predetermined heating conditions shown in table 2. The plate temperature and the baking time vary depending on the sample, but the heating temperature is adjusted to 180 to 400 ℃ and the baking time is adjusted to 5 to 70 seconds.

On the other hand, the average particle size was measured in advance. The organic resin emulsion was diluted with distilled water, and the fluororesin powder was dispersed in distilled water for about 1 minute by an ultrasonic cleaner, and the logarithmic mean particle diameter was measured by using a commercially available particle diameter measuring apparatus based on a laser diffraction method according to JIS method (JIS Z8826).

The methods for evaluating the samples of Nos. 1 to 26 produced will be described in detail below.

The insulation property is lower than 5 Ω · cm based on the interlayer resistance measured according to JIS method (JIS C2550)²The piece/piece is set as "x", and it is set to 5. omega. cm²Per piece-10 omega cm²The value of ". DELTA" is set for the case of/. DELTA ". Then, the thickness of the film was adjusted to 10. omega. cm²Per piece-50 omega cm²The value of each piece was determined as "O", and the value was determined to be 50. omega. cm²The one greater than/slice is set as ". circinata".

The adhesion was evaluated by winding a sample to which the tape was applied around a metal rod having a diameter of 10mm, 20mm or 30mm, peeling off the tape, and evaluating the adhesion from the peeling trace. The one that did not peel off even at a bend of 10mm phi was set to 10mm phi "OK", the one that did not peel off at 20mm phi was set to 20mm phi "OK", the one that did not peel off at 30mm phi was set to 30mm phi "OK", and the one that peeled off at both of them was set to "OUT".

Regarding the corrosion resistance under a wet environment, first, a 5% NaCl aqueous solution was allowed to naturally fall on a sample for 1 hour in an atmosphere of 35 ℃ according to the salt spray test of JIS method (JIS Z2371). Subsequently, the sample was held at 60 ℃ and 40% humidity for 3 hours and at 40 ℃ and 95% humidity for 3 hours as 1 cycle, and such a cycle was repeated 5 times. Then, the rust area of the sample was evaluated by 10 points. The evaluation criteria are as follows.

10: absence of rust

9: very little rust (area ratio of 0.1% or less)

8: the area ratio of rust is more than 0.1% and not more than 0.25%

7: the area ratio of rust is more than 0.25% and not more than 0.50%

6: the area ratio of rust is more than 0.50% and not more than 1%

5: the area ratio of rust is more than 1% and not more than 2.5%

4: the area ratio of rust is more than 2.5% and not more than 5%

3: the area ratio of rust is more than 5% and 10% or less

2: the area ratio of rust is more than 10% and 25% or less

1: the area ratio of rust is more than 25% and 50% or less

The contact angle was measured by using a contact angle meter PG-X manufactured by マツボー. The measurement values are the average of 10 measurements.

Regarding the appearance, the one that was glossy, smooth and uniform was set to 5, the one that was glossy but slightly poor in uniformity was set to 4, the one that was slightly glossy, smooth but poor in uniformity was set to 3, the one that was less glossy, slightly poor in smoothness and poor in uniformity was set to 2, and the one that was poor in gloss, uniformity and smoothness was set to 1.

Regarding heat resistance, the surface of the steel sheet was wiped with a wire mesh of 2mm × 30mm under a load of 100gf (about 0.98N) after stress relief annealing at 750 ℃ for 2 hours in a nitrogen atmosphere, and the peeling state of the insulating coating film was evaluated. As a result, the one with no peeling was set to 5, the one with less peeling was set to 4, the one with marked peeling was set to 3, the one with severe peeling status was set to 2, and the one with no wire mesh wiping was set to 1. The evaluation results are shown in table 3 below.

TABLE 3

As shown in Table 3, it has been found that samples Nos. 1 to 9 according to examples of the present invention are excellent in corrosion resistance under a wet environment. Furthermore, it is clear that samples Nos. 1 to 9 are excellent in insulation, adhesion, and appearance in addition to corrosion resistance. In addition, in samples nos. 10 to 25 according to comparative examples, the effect of corrosion resistance is often low, and there is no case where the corrosion resistance, insulation property, adhesion and appearance are all excellent.

As described above, the electrical steel sheet according to the embodiment of the present invention has good corrosion resistance in a wet environment and also has good other properties related to the insulating coating film in the production of the laminated iron core.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to these examples. It is obvious that various modifications and alterations can be made within the scope of the technical idea of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains, and it is needless to say that these modifications and alterations belong to the technical scope of the present invention.

Industrial applicability

According to the present invention, an electrical steel sheet having excellent corrosion resistance under a wet environment and excellent in adhesion, space factor, punchability, and other properties can be used as an iron core material of an electrical device or the like.

Claims (4)

1. An electromagnetic steel sheet characterized by: the surface of the steel sheet is covered with an insulating coating film in which:

a mixture comprising 100 parts by mass of a metal phosphate and 1 to 50 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 [ mu ] m: 100 parts by mass, and

copolymers of fluoroolefins with ethylenically unsaturated compounds on a solids basis: 0.5 to 10 parts by mass,

the ethylenically unsaturated compound has a functional group that does not contain fluorine.

2. An electromagnetic steel sheet characterized by: the surface of the steel sheet is covered with an insulating coating film in which:

a mixture comprising 100 parts by mass of colloidal silica and 40 to 400 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 [ mu ] m: 100 parts by mass, and

copolymers of fluoroolefins with ethylenically unsaturated compounds on a solids basis: 0.5 to 10 parts by mass,

the ethylenically unsaturated compound has a functional group that does not contain fluorine.

3. A method for manufacturing an electrical steel sheet, comprising the steps of:

mixing 1 to 50 parts by mass of an organic resin containing a mixture or copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 μm, in terms of solid content, with respect to 100 parts by mass of a metal phosphate;

a step of preparing a treatment liquid in which a copolymer of a fluoroolefin and an ethylenically unsaturated compound is mixed in an amount of 0.5 to 10 parts by mass in terms of solid content, based on 100 parts by mass of the solid content of the mixture of the metal phosphate and the organic resin;

applying the prepared treatment liquid to the surface of a steel sheet; and

a step of baking and drying the steel sheet coated with the treatment liquid at an arrival temperature of 200 to 380 ℃ for 15 to 60 seconds,

the ethylenically unsaturated compound has a functional group that does not contain fluorine.

4. A method for manufacturing an electrical steel sheet, comprising the steps of:

mixing 40 to 400 parts by mass of an organic resin containing a mixture or a copolymer of 1 or 2 or more selected from among acrylic resins, epoxy resins and polyester resins having an average particle diameter of 0.05 to 0.50 μm in terms of solid content, based on 100 parts by mass of colloidal silica;

a step of preparing a treatment liquid in which a copolymer of a fluoroolefin and an ethylenically unsaturated compound is mixed in an amount of 0.5 to 10 parts by mass in terms of solid content, based on 100 parts by mass of the solid content of the mixture of the colloidal silica and the organic resin;

applying the prepared treatment liquid to the surface of a steel sheet; and

a step of baking and drying the steel sheet coated with the treatment liquid at an arrival temperature of 200 to 300 ℃ for 15 to 60 seconds,

the ethylenically unsaturated compound has a functional group that does not contain fluorine.