JP2002047576A - Treating solution and treating method for forming insulating film on silicon steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an inorganic or semiorganic type insulating film bakable at a temperature of 200 to 330 deg.C same as that in the case of a bichromate treating solution and excellent in water resistance and adhesive properties even in the case of a thin film with the coating weight of <=1.0 g/m2 on the surface of a silicon steel sheet by using a phosphate treating solution which does not contain chromium. SOLUTION: A treating solution obtained by adding a phosphonic chelating agent to an aqueous solution of polyvalent metal phosphate in such a manner that the ratio between the total ΣMi of the product between the molar number of the metallic atoms in the polyvalent metal phosphate and the number of their valencies and the total ΣOi of the product between the molar number of the chelating agent and the number of acid radicals in the molecules (ΣOi/ΣMi) is controlled to the range of 0.1 to 5 is used. The treating solution may further contain one or more kinds selected from water-based synthetic resin, boric acid and colloidal silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing solution and a processing method for forming an insulating film on the surface of a magnetic steel sheet.
In particular, it does not contain harmful compounds such as hexavalent chromium and can be manufactured at the same baking temperature as dichromate-based coatings, which were conventionally common as non-oriented electrical steel sheet insulating coatings. An electrical steel sheet that has excellent water resistance that cannot be obtained with a phosphate-based insulating film, and is particularly excellent in film forming properties, adhesion, and water resistance when forming a thin insulating film of 1.0 g / m ² or less. And a method for forming an insulating film.

[0002]

2. Description of the Related Art Insulating coatings of electromagnetic steel sheets used for iron cores of rotating machines and transformers have not only interlayer resistance but also user convenience (punching property, welding property, heat resistance, caulking property) and the like. Various characteristics are required.

[0003] Insulating films for non-oriented electrical steel sheets that are currently generally used are roughly classified into the following three types: an inorganic film that emphasizes heat resistance and can be subjected to strain relief annealing; An inorganic-organic mixed semi-organic film that can be strain-annealed to achieve compatibility. An organic film that emphasizes punchability and cannot be strain-annealed.

[0004] Among them, an insulating film that can be used for strain relief annealing and contains an inorganic component is widely used.
In particular, semi-organic coatings have become predominant because punching properties are much better than inorganic coatings.

Hitherto, dichromate has been widely used as a material for forming the inorganic component in the insulating film. The insulating film using dichromate is
A treatment liquid obtained by mixing an organic reducing agent such as ethylene glycol or glycerin with an aqueous solution containing hexavalent chromium and a polyvalent metal salt is applied to an electromagnetic steel sheet, and then heated to bake the coating film.
It is formed by reducing valent chromium to trivalent chromium and forming a film. The baking is completed at a temperature of 200 ° C. to 330 ° C. in a short time within 1 minute. However, hexavalent chromium used for forming this insulating film is highly toxic, and there is a concern that it may harm human health involved in the production. Further, trivalent chromium contained in the formed insulating film is much less toxic than hexavalent chromium, but cannot be said to be completely harmless. Therefore, it cannot be denied that the insulating film using dichromate may be slightly harmful to humans or the environment at the time of manufacturing and at the product stage, and a non-chromium type insulating film using no chromium is required. It has become

[0006] Phosphate is an inorganic component that can be used for forming an insulating film in the same manner as dichromate. Phosphate aqueous solution is a system that can form a few films as an inorganic component,
Since it is obtained at a relatively low cost, it has been conventionally studied as an inorganic component for inorganic and semi-organic insulating films (for example, Japanese Patent Publication No. 53-28375).

However, unlike the dichromate-based reduction reaction, the phosphate-based insulating film polymerizes the phosphate due to the progress of condensation by a dehydration reaction, and increases the water insolubility of the film to form a film. Let it. Therefore, in order to form an insulating film having high water resistance, it is necessary to bake at a higher temperature (eg, 300 to 400 ° C.) than the dichromate-based treatment liquid after applying the treatment liquid. When the baking temperature increases, there are the following problems.

The amount of heat and / or time required for baking increases, which is disadvantageous from the viewpoint of industrial productivity and economy. Some of the resin contained in the general-purpose semi-organic film may be thermally decomposed, and the performance (adhesion, corrosion resistance, punching property) of the film may be reduced. If a resin having high heat resistance is used, this problem is reduced, but such a resin is expensive and is industrially difficult to employ from the viewpoint of economy.

[0009] Examples of the phosphate-based insulating film include an aluminum monophosphate and an organic emulsion resin to increase the particle size of the emulsion or to make other components (crosslinked resin powder, alcohol, or It has been proposed in JP-A-5-78855, JP-A-6-330338, JP-A-11-131250 and JP-A-11-152579 that an insulating film is formed by using a treatment solution further containing an organic acid metal salt. Have been.

However, as a result of investigations by the present inventors, the processing liquids described in these publications have particularly small film thicknesses.
In the case of forming a (deposition amount of about 1.0 g / m ² or less) of a thin film of insulating coating, film forming property is insufficient, unless a higher baking temperature, water resistance and adhesion of the insulating coating is reduced, a thin film Was found to be inferior in performance. An electromagnetic steel sheet provided with a thin insulating film is required particularly in applications where importance is placed on weldability and applications where importance is placed on automated caulking.

For example, JP-A-11-131250 and JP-A-11-131250
In each of the publications 152579, the corrosion resistance test result of the film baked at 200 ° C or 250 ° C is shown by the wetting test, and the corrosion resistance is evaluated based on the presence or absence of rust. Is not recognized, it cannot be said that the water resistance is sufficient. This is because even if rust does not occur, performance deterioration such as stickiness and slipperiness is reduced only by whitening of the insulating film.

[0012]

There have been several examples of the use of a phosphate-based coating as a semi-organic coating for non-oriented electrical steel sheets. Since a high baking temperature is required as compared with the system, it has been used only for very limited applications.

It is possible to form a film without using chromium at a baking temperature as low as that of dichromate, and even in such a case, it has excellent water resistance such as resistance to whitening in a wet test, as well as excellent adhesion and insulating properties. Until now, there has been no treatment solution for forming an insulating film on an electromagnetic steel sheet that has various properties required for an insulating film and exhibits excellent film forming properties even in a thin film. The present invention provides such a treatment liquid and a method for forming an insulating film on a magnetic steel sheet using the treatment liquid.

[0014]

Means for Solving the Problems The present inventors can form an insulating film on an electromagnetic steel sheet using a phosphate-based treatment solution at the same baking temperature as that of a conventional dichromate-based treatment solution. Can form a film with excellent water resistance and adhesion,
Furthermore, intensive studies were conducted with the aim of developing a processing solution capable of forming a good film even in the case of a thin insulating film having a coating amount of 1.0 g / m ² or less.

As a result, it has been found that the above-mentioned object can be achieved by a treatment solution obtained by adding a chelating agent containing an acid group, particularly a phosphonic acid group, to an aqueous solution of a water-soluble polyvalent phosphate. Completed.

In the treatment liquid for forming an insulating film on an electromagnetic steel sheet according to the present invention, a water-soluble polyvalent metal phosphate (A) and a chelating agent having an acid group (B) are dissolved in an aqueous solvent. The sum of the product of the number of moles of metal atoms contained in the polyvalent metal phosphate (A) and its valence is defined as ΔMi, and the chelating agent
Assuming that the sum of the product of the number of moles of (B) and the number of acid groups in the molecule is ΣOi, the ratio of (A) and (B) satisfies the following equation (1).

0.1 ≦ {Oi / {Mi ≦ 5}} (1) In a preferred embodiment, the polyvalent metal phosphate (A) is aluminum monophosphate and / or magnesium monophosphate, and its treatment The concentration in the liquid is in the range of 1 to 50% by mass, and the chelating agent (B) is at least partially a phosphonic acid compound.

The treatment liquid for forming an insulating film of the present invention may further contain a synthetic resin so as to form a semi-organic film. The synthetic resin is used after being dispersed or dissolved in a phosphate aqueous solution. In this case, it is preferable to use mainly an aqueous synthetic resin. An aqueous synthetic resin is a water-soluble synthetic resin,
It is meant to include water-dispersible synthetic resins and underwater emulsion-type synthetic resins. Further, the treatment liquid of the present invention may further contain boric acid and / or colloidal silica separately from or in addition to the synthetic resin.

In the method for treating an electromagnetic steel sheet using the treatment liquid of the present invention, the treatment liquid is applied to at least one surface of the electromagnetic steel sheet, and then heated to bake the coating, thereby forming an insulating film on the surface of the electromagnetic steel sheet. Consisting of This treatment method is particularly advantageous when applied to the formation of a thin insulating film in which the amount of the formed insulating film is 1.0 g / m ² or less per side. An excellent insulating film that resists whitening can be formed in the test. Further, the baking temperature of the coating film (the highest attained plate temperature, the same applies hereinafter) is preferably in the range of 200 to 330 ° C. as in the case of the conventional dichromate-based treatment liquid.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The type of magnetic steel sheet to be treated according to the present invention is not particularly limited. The electrical steel sheet may be either non-oriented or oriented, and may be either a hot-rolled steel sheet or a cold-rolled steel sheet. A general electromagnetic steel sheet is a low carbon steel sheet containing about 1 to 5% of Si, but ordinary steel containing almost no Si can be used as the electromagnetic steel sheet.

The treatment liquid used for forming the insulating film on the magnetic steel sheet in the present invention is obtained by dissolving a water-soluble polyvalent metal phosphate (A) and a chelating agent (B) having an acid group in an aqueous solvent. Solution. The aqueous solvent may be water, but a mixed solvent of water and a water-miscible organic solvent (eg, alcohol, ketone, etc.) can also be used.

The ratio of the polyvalent metal phosphate (A) to the chelating agent (B) is determined by the sum of the product of the number of moles of metal atoms contained in (A) and the valence, ΔMi, and the mole of (B) Assuming that the sum of the product of the number and the number of acid groups in the molecule is ΣOi, the ratio satisfies the following equation (1).

0.1 ≦ ΣOi / ΣMi ≦ 5 ‥‥ (1) If the value of ΣOi / ΣMi is less than 0.1, the film-forming property when forming a thin insulating film is deteriorated, and a uniform insulating film is formed. And water resistance decreases. On the other hand,
When the value of i / ΣMi is greater than 5, the viscosity of the processing solution increases, the inorganic components in the processing solution settle with time, and the quality of the formed insulating film is not stable.
Its water resistance may be poor. A preferred range of the value of ΣOi / ΣMi is 0.2 to 3.

By using a processing solution in which a chelating agent is added to an aqueous solution of a polyvalent metal phosphate, film forming properties, adhesion, and the like can be improved.
Further, the reason why the ability to form a thin insulating film having a coating weight of 1.0 g / m ² or less is improved has not been clearly elucidated, but the present invention is thought to involve the following mechanism. Are speculating.

When a processing solution containing no chelating agent (ie, an aqueous solution of a polyvalent metal phosphate) is applied to the surface of the magnetic steel sheet, the second solution dissociated from the polyvalent metal phosphate present in the processing solution. Since the monophosphate ions and free phosphoric acid are strongly acidic, the surface of the steel sheet is etched, and iron ions are eluted into the treatment solution. The eluted iron ions and primary phosphate ions or free phosphoric acid are combined by the concentration of the treatment solution accompanying the drying, and fine iron phosphate particles are formed from the initial stage of the drying. Since these iron phosphate fine particles are crystalline, they give the appearance of a cloudy film and impair the film formability, or cause film peeling from iron phosphate as a base to impede the adhesion, thereby preventing water resistance. It also reduces the quality. In particular, in the case of a thin film having a coating weight of 1.0 g / m ² or less, the diameter of iron phosphate particles generated in the film
Since the ratio of (short diameter or long diameter) to the film thickness is large, the film is likely to have a defect, and the adverse effect on the film formability, adhesion and water resistance is further increased.

When a treatment solution in which a chelating agent is added to a polyvalent metal phosphate is applied to the surface of an electromagnetic steel sheet, iron ions eluted by etching of the steel sheet surface are chelated before iron phosphate particles are formed. It is captured by the agent and stabilized in the applied undried processing liquid. It is considered that the chelating agent is almost uniformly dispersed in the processing solution, and it is presumed that as the drying and baking progresses, a part of the chelating agent itself is dehydrated and condensed, and is stabilized as an amorphous film. You.

The water-soluble polyvalent metal phosphate compound (A) is a base component for forming an insulating film. If the metal is a monovalent alkali metal, a water-resistant film cannot be formed, so a polyvalent metal of phosphoric acid is used.

As the water-soluble polyvalent metal phosphate (A),
It is preferred to use one or both of aluminum monophosphate and magnesium monophosphate. here,
Aluminum monophosphate has Al / P molar ratio of 0.7 / 3 ~
1.2 / 3 magnesium monophosphate is Mg
/ P having a molar ratio of 0.7 / 2 to 1.2 / 2.
The metal ions of the polyvalent metal phosphate are difficult to obtain a high-concentration processing solution and are industrially inexpensive because of the above-mentioned reasons.
Types (aluminum salts and magnesium salts) are preferred, but other divalent or trivalent metal salts (Ca, Sr, Ba, Zn salts, etc.) can also be used. Further, a commercially available aqueous solution of phosphate to which a metal or metal oxide or hydroxide is added to increase the ratio of polyvalent metal to phosphate ion can be used.

The concentration of the polyvalent metal phosphate in the treatment solution is 1 to
The range is preferably 50% by mass, more preferably 2 to 30% by mass. If the concentration is less than 1% by mass, the film-forming properties are poor, and the water resistance tends to decrease. On the other hand, if this concentration exceeds 50%, the stability of the treatment liquid is reduced, solids settle, and the viscosity increases, making it difficult to form a uniform film.

The chelating agent (B) improves the film formability of the polyvalent metal phosphate and enables the formation of a film having good water resistance even under low-temperature baking conditions. In addition, chelating agent (B)
Has an effect of enabling formation of a uniform, amorphous, and dense insulating film, which is difficult with polyvalent metal phosphate alone.

As the chelating agent (B), a chelating agent having an acid group is used. This is because the treatment liquid contains a polyvalent metal phosphate and is acidic. For example, a chelating agent having no acid group, such as ethylenediamine, reacts with primary phosphate ions in the processing solution and loses the ability to form chelate or trap metal.

As the chelating agent (B) having an acid group, carboxylic acid compounds such as oxycarboxylic acid, dicarboxylic acid and aminocarboxylic acid can be used, but the phosphonic acid (phosphorous acid) compound is the same phosphoric acid. It is preferable because the effect of improving the water resistance of the film is large. Further, a phosphonic acid-based chelating agent and a carboxylic acid-based chelating agent can be used in combination.

Specific examples of the phosphonic acid chelating agent include hydroxyethylidene mono- and di-phosphonic acids, aminotrimethylene phosphonic acid and the like. Among the carboxylic acid chelating agents, specific examples of oxycarboxylic acids include glycolic acid and lactic acid, specific examples of dicarboxylic acids include oxalic acid, malonic acid, and succinic acid, and specific examples of aminocarboxylic acids include ethylenediamine. Examples thereof include tetraacetic acid and nitrilotriacetic acid. All of the above are merely examples, and other compounds can be used.

Japanese Patent Application Laid-Open No. 11-131250 discloses a treatment solution in which an organic acid metal salt is added to aluminum monophosphate, and a compound which becomes a chelating agent such as succinic acid as an organic acid is also exemplified. However, this organic acid is used in the form of a metal salt and naturally does not function as a chelating agent. For example, if succinic acid is used as a chelating agent in the present invention, it must be in free form.

The processing solution for forming an insulating film of the present invention contains a synthetic resin,
Preferably, an aqueous synthetic resin may be added. As described above, the aqueous synthetic resin may be any one of an emulsion type, a water dispersible type, and a water soluble type. As specific examples of the synthetic resin, acrylic resin, acrylic styrene resin, alkyd resin, polyester resin, silicone resin, fluororesin, polyolefin resin, styrene resin, vinyl acetate resin, epoxy resin, phenol resin,
Urethane resins, melamine resins, and the like. One or more synthetic resins can be added.

When the synthetic resin is added to the treating solution, the amount of the resin added is 3 to 100 parts by mass per 100 parts by mass of the polyvalent metal phosphate.
It is preferably within the range of parts by mass. If the amount of the synthetic resin is less than 3 parts by mass, almost no improvement in the punching property is obtained, and if it exceeds 100 parts by mass, the interlayer resistance after strain relief annealing may decrease. The addition amount of the synthetic resin is more preferably 5 to 5 parts by mass, and further preferably 7 to 30 parts by mass.

In order to improve the corrosion resistance especially after the strain relief annealing, boric acid may be added to the treatment liquid of the present invention. The amount of boric acid added is preferably not more than 50 parts by mass in terms of B per 100 parts by mass of P of the polyvalent metal phosphate. If the addition amount is excessive, the interlayer resistance and the corrosion resistance after strain relief annealing are improved, but the boric acid cannot be completely dissolved in the treatment liquid and may precipitate in the liquid. This addition amount is more preferably 2 to 20 parts by mass.

[0038] Colloidal silica may be added to the treatment liquid of the present invention in order to improve interlayer resistance. The amount of colloidal silica to be added is 10 in terms of P of polyvalent metal phosphate.
It is preferable to be 50 parts by mass or less per 0 parts by mass in terms of Si. If the added amount of silica is too large, the stability of the treatment liquid may be lost or the surface properties may be impaired. This addition amount is more preferably 2 to 30 parts by mass.

In addition to the above, if desired,
Other additives such as a rust inhibitor, a defoaming agent, and a treatment liquid stabilizer can be appropriately compounded. Using the treatment liquid of the present invention, apply it to the surface of a base magnetic steel sheet (usually, both sides, but it is also possible to apply it to one side), and heat it to bake the coating film. A phosphate insulating film having excellent adhesion is formed.

The coating method of the treatment liquid is not particularly limited, and various coating methods generally used in industry such as a roll coater, a curtain flow coater, a spray coating, a knife coater, and a dipping can be applied.

The baking of the film can also be carried out by a method usually employed, such as a hot air method, an infrared method, an induction heating method, or the like.
Baking temperature comparable to conventional dichromate, i.e. 200-330
A film formed by short-time seizure within 1 minute within a temperature range of ° C. is formed into a film having excellent water resistance and adhesion, and excellent insulation. The water resistance of this insulating film is sufficient to withstand whitening in a wet test.

The amount of the insulating film deposited on the magnetic steel sheet was 0.1 g / m ²
As described above, the amount is preferably 3 g / m ² or less. When the amount of adhesion is less than 0.1 g / m ² , not only uniform coating becomes difficult, but also seizure resistance, corrosion resistance, and interlayer resistance during annealing are insufficient. If the adhesion amount exceeds 3 g / m ² , the margin for improving the interlayer resistance is saturated, and
The adhesion of the film is reduced. Interlayer resistance, ie
When insulation is mainly required, it is preferable to set the adhesion amount to 1.0 g / m ² or more. Conversely, for example, when the improvement of the weldability is required in order to improve the productivity in the production of the iron core and the rotating machine is less than 1.0 g / m ^2, preferably 0.5 g / m ² or less of membrane Is required. In this way, the film thickness can be set according to the performance that is emphasized in the application. The treatment liquid of the present invention has a feature that it has good film formability even when a thin film having an adhesion amount of 1.0 g / m ² or less is formed, and can form an insulating film having excellent adhesion and water resistance. It is advantageous to apply to the formation of such a thin insulating film.

[0043]

The present invention will be specifically illustrated by the following examples, but the present invention is not limited by these examples. The percentages and parts in the examples are% by mass and parts by mass unless otherwise specified.

Example 1 A 30% aqueous solution of aluminum monophosphate (Al / P ratio = 0.9 / 3) was mixed with 1-hydroxyethylidene-1,1-diphosphonic acid (k
Was added and dissolved so that the value of ΣOi / ΣMi could take various values, or a treatment liquid for forming an insulating film for a test was prepared without addition. For comparison, a treatment liquid was prepared by adding 5 parts of ethylene glycol or aluminum citrate to 100 parts of aluminum phosphate. These treatment solutions were stored at 40 ° C. for 6 months, and the stability of the treatment solutions was examined. The case where no solid matter was generated in the treatment liquid after storage was evaluated as “○”, and the case where a solid matter was generated was evaluated as “x”.

Each of these treatment liquids is applied to both sides of a 0.5 mm-thick electromagnetic steel sheet containing 0.1% Si by a roll coater so that the amount of the applied insulating film after baking is 0.1 to ² g / m ^2. After that, use a hot blast stove to raise the maximum plate temperature to 270 ° C.
The coating film was baked by heating for 30 seconds to form an insulating film. The water resistance and adhesion of the obtained magnetic steel sheet with an insulating film were evaluated as described below. Table 1 shows the results together with the composition of the processing solution.
Shown in

A test piece of an electromagnetic steel sheet with an insulating film was hung in a wet tester having a water resistance of 50 ° C. and 98% RH, and the state of the film surface after 72 hours was checked for stickiness by a tentacle and for whitening by color difference measurement. Investigated according to degree. The evaluation was performed in the following four stages, and ○ and ◎ were evaluated as acceptable. For whitening of the film, use Minolta's total reflection type color difference meter CR-300 and specify the L specified in JIS-Z8730.
The value (numerical value representing whiteness) was measured before and after the test, and whitening was judged based on the magnitude of the change (ΔL) in the L value.

◎: no stickiness, no whitening (ΔL ≦ 2), ：: no stickiness, slight whitening (ΔL ≦ 5), Δ: sticky, whitening (ΔL ≦ 10), ×: sticky, significant whitening (ΔL ≦ 20).

Adhesion of Insulating Film A test piece of an electromagnetic steel sheet with an insulating film having a length of 50 mm and a width of 25 mm was wound around a 5 mm-diameter iron rod, and a tape peeling test was carried out on the wound outer portion to remain on the steel sheet. The state of the insulating film thus obtained was investigated. The following four stages are used for evaluation.
◎ and ○ were accepted.

◎: No film peeling, ：: Film peeling occurred (5% or less in area ratio), Δ: Film peeling occurred (more than 5% in area ratio, 30% or less), ×: Film peeling occurred (in area ratio) Over 30%).

[0050]

[Table 1] As can be seen from Table 1, an insulating film containing only aluminum monophosphate without adding a chelating agent has poor water resistance,
The tendency becomes stronger as the amount of adhesion becomes smaller, and the adhesion becomes worse. In contrast, when using a treatment liquid by blending a chelating agent according to the present invention, water resistance and adhesion is significantly improved, even with an insulating film of a very thin film of 0.1 to 0.2 g / m ^2, sufficiently adhesion and water resistance To be good. However, if the amount of the chelating agent is too small, this improvement cannot be obtained,
If the added amount of the chelating agent is too large, the stability of the treatment liquid will be impaired.

Regarding the manufactured electromagnetic steel sheet with an insulating film,
The film performance after the strain relief annealing at 750 ° C. for 2 hours was examined with respect to adhesion and interlayer resistance. Of the test No. samples in Table 1, samples 1 to 3 and 5 to 8 were wrapped around a round bar having a length of 50 mm and a diameter of 20 mm after annealing. Peeling was observed. 6 ~
16 samples had good adhesion. On the other hand, the sample No. 4 had film unevenness, and the interlayer resistance after strain relief annealing was 0.5 Ωcm ² / sheet or less. Other samples showed an interlayer resistance of 3 to 100 Ωcm ² / sheet, and showed sufficient insulation after annealing.

Example 2 An aqueous solution of 30% concentration of aluminum monophosphate (Al / P ratio = 0.9 / 3) or 30% concentration of magnesium monophosphate (Mg / P ratio = 0.85 / 2) was prepared. 1-hydroxyethylidene-1,1-diphosphonic acid (k1), aminotrimethylene phosphonic acid (k
2) and / or glycolic acid as (k3) with {Oi
/ ΣMi was added and dissolved at a rate of 1 value. To this polyvalent metal phosphate / chelating agent aqueous solution, an acrylic emulsion having a glass transition point of 20 ° C. was added to a polyvalent metal phosphate 100
20 parts by weight per part by weight, and optionally, 20 parts by weight of boric acid or 10 parts by weight of colloidal silica in terms of Si with respect to 100 parts in terms of P of the polyvalent metal phosphate. ,
The mixture was sufficiently stirred to prepare a treatment liquid.

Using this treatment liquid, insulating films were formed on both sides of the magnetic steel sheet, and the water resistance and adhesion were evaluated in the same manner as in Example 1 except that the baking temperature (maximum reached plate temperature) was changed. . The test results are shown in Table 2 together with the composition of the processing solution and the baking temperature (heating time is 30 seconds).

[0054]

[Table 2] As can be seen from Table 2, even in the case of a semi-organic insulating film to which a synthetic resin was added and which had good punching properties, an insulating film having excellent water resistance and adhesion could be formed with a thin insulating film. Also, changing the type of polyvalent metal phosphate or chelating agent, changing the baking temperature, or adding an additive such as boric acid or colloidal silica,
No remarkable influence on water resistance and adhesion was observed, and both were good results.

[0055]

The treatment liquid for forming an insulating film of an electrical steel sheet according to the present invention does not contain harmful substances such as chromium and has excellent film-forming properties. at the level of the baking temperature and the amount of deposition is 1.0 g / m ² or less, particularly 0.5
Even with a thin film having a thickness of g / m ² or less, an insulating film having excellent water resistance and adhesion can be formed. As long as the coating weight is 0.1 g / m ² or more, this insulating film has a practically sufficient interlayer resistance (JI
5 to 10Ω · cm ² / sheet or more as measured according to S-C2550).

Therefore, according to the present invention, an insulating film having necessary performances such as water resistance, insulation, adhesion, etc. can be changed from a thick film to a thin film depending on the application without fear of adverse effects on the environment and personnel. It can be formed on the surface of the electromagnetic steel sheet relatively inexpensively with the adhesion amount up to. This insulating film has excellent thin film performance (film forming property in thin film, adhesion, and water resistance) not found in the conventional polyvalent metal phosphate-based film. The electrical steel sheet with an insulating film manufactured using the treatment liquid of the present invention can be used for a wide range of uses including motor applications.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 22/20 C23C 22/20 22/22 22/22 F term (Reference) 4D075 BB28Z BB93Z CA23 DA06 DB03 EA02 EA06 EC01 EC03 EC54 4K026 AA03 BA03 BB05 BB10 CA16 CA18 CA24 CA38 CA39 CA41 DA02 DA15 EB11 4K033 TA03

Claims (9)

[Claims] 1. A polyvalent metal phosphate which is water-soluble in an aqueous solvent.
(A) and a treatment solution in which a chelating agent (B) having an acid group is dissolved, and the sum of the product of the number of moles of metal atoms contained in the polyvalent metal phosphate (A) and its valence is calculated asと し Mi and the sum of the product of the number of moles of the chelating agent (B) and the number of acid groups in the molecule is ΣOi
Wherein the proportion of (A) and (B) satisfies the following equation (1): a treatment liquid for forming an insulating film on an electromagnetic steel sheet. 0.1 ≦ ΣOi / ΣMi ≦ 5 ‥‥ (1) 2. The treatment liquid according to claim 1, wherein the polyvalent metal phosphate (A) is aluminum monophosphate and / or magnesium monophosphate. 3. The treatment liquid according to claim 1, wherein at least a part of the chelating agent (B) is a phosphonic acid compound. 4. The treatment liquid according to claim 1, wherein the concentration of the polyvalent metal phosphate (A) is in the range of 1 to 50% by mass. 5. The treatment liquid according to claim 1, further comprising a synthetic resin. 6. The processing solution according to claim 1, further comprising boric acid and / or colloidal silica. 7. A method comprising applying the treatment liquid according to claim 1 to at least one surface of an electromagnetic steel sheet, and then heating and baking the coating film to form an insulating film on the surface of the electromagnetic steel sheet. , Electrical steel sheet processing method. 8. The method according to claim 7, wherein the coating weight of the formed insulating film is 1.0 g / m ² or less per one side. 9. The baking temperature (maximum attained plate temperature) of the coating film is
The method according to claim 7 or 8, wherein the temperature is in the range of 200-330 ° C.