Title of invention: Non-oriented electrical steel sheet
Technical field
[0001]
The present invention relates to non-oriented electrical steel sheets.
Background technology
[0002]
An insulating coating is generally formed on the surface of non-oriented electrical steel sheets. Insulating coatings are required to have not only insulating properties but also various coating properties such as corrosion resistance, adhesion, heat resistance to withstand annealing, stability as a coating, and the like. Conventionally, insulating coatings contain a chromic acid compound to achieve the above coating properties at an extremely high level. However, in recent years, with increasing awareness of environmental problems, development of insulating coatings containing no chromic acid compounds is underway.
[0003]
For example, Patent Literatures 1 and 2 disclose a non-oriented electrical steel sheet having an insulating coating mainly composed of one type of metal phosphate selected from specific metal elements and an organic resin. .
[0004]
In addition, Patent Document 3 discloses a surface treatment agent for non-oriented electrical steel sheets in which aluminum phosphate, an organic resin, and an OH-containing organic compound are blended in specific proportions. Furthermore, in Patent Document 4, after performing phosphoric acid pickling treatment and drying treatment, when forming a phosphoric acid compound coating on the steel plate surface, drying treatment is performed based on the relationship between a predetermined temperature and drying time. A method for manufacturing an electrical steel sheet with an insulating coating is disclosed.
prior art documents
patent literature
[0005]
Patent document 1: JP-A-6-330338
Patent document 2: JP-A-11-80971
Patent document 3: JP-A-11-152579
Patent Document 4: JP-A-2003-193251
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0006]
However, when an insulating film containing no chromic acid compound is used as disclosed in Patent Documents 1 to 3, while exhibiting excellent insulation, punchability (that is, workability) is improved, but adhesion There is still room for improvement in realizing an insulating coating that further combines toughness, moisture absorption resistance, corrosion resistance and heat resistance.
[0007]
Furthermore, although the technique disclosed in Patent Document 4 exhibits excellent appearance and adhesion, it requires a prior pickling treatment with phosphoric acid and a drying treatment after the pickling treatment. However, there was a problem with industrial productivity.
[0008]
The present invention has been made in view of such problems, and has an insulating coating that does not contain a chromate compound and is excellent in insulation, workability, adhesion, moisture absorption resistance, corrosion resistance and heat resistance. An object of the present invention is to provide a grain-oriented electrical steel sheet.
Means to solve problems
[0009]
The present invention has been made to solve the above problems, and its gist is the following non-oriented electrical steel sheet.
[0010]
(1) comprising a base steel plate and an insulating coating formed on the surface of the base steel plate,
The insulating coating contains a total of 50% by mass or more of a metal phosphate, an organic resin, and a water-soluble organic compound with respect to the total mass of the insulating coating,
The metal phosphate contains at least aluminum as a metal element,
The organic resin has an SP value within the range of 18.0 (MPa) 0.5 or more and 24.0 (MPa) less than 0.5,
The water-soluble organic compound has an SP value within the range of 19.0 (MPa) 0.5 or more and 35.0 (MPa) less than 0.5,
When the insulating coating is measured by an X-ray diffraction method, the crystallinity of aluminum phosphate calculated from the peak attributed to the metal phosphate is 0.5 to 5.0%. be,
　Non-oriented electrical steel sheet.
[0011]
(2) the metal phosphate further contains a divalent metal element M other than aluminum as a metal element,
The non-oriented electrical steel sheet according to (1) above.
[0012]
(3) the metal element M is one or more selected from the group consisting of Zn, Co, Mg, Mn, and Ni;
The non-oriented electrical steel sheet according to (2) above.
[0013]
(4) the content of the organic resin is 3 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the metal phosphate;
The non-oriented electrical steel sheet according to any one of (1) to (3) above.
Effect of the invention
[0014]
According to the present invention, it is possible to obtain a non-oriented electrical steel sheet that does not contain a chromate compound and has an insulating coating that is excellent in insulation, workability, adhesion, moisture absorption resistance, corrosion resistance, and heat resistance. .
Brief description of the drawing
[0015]
1] Fig. 1 is a schematic diagram for explaining the structure of a non-oriented electrical steel sheet according to an embodiment of the present invention. [Fig.
[Fig. 2] Fig. 2 is an example of an XRD spectrum of a non-oriented electrical steel sheet.
3 is a schematic diagram for explaining the degree of crystallinity of an insulating coating; FIG.
MODE FOR CARRYING OUT THE INVENTION
[0016]
The inventors of the present invention have obtained the following knowledge as a result of extensive studies on methods for realizing an insulating coating that has both insulation, workability, adhesion, moisture absorption resistance, corrosion resistance, and heat resistance.
[0017]
(a) Insulation, punchability, adhesion, hygroscopic resistance, corrosion resistance, and heat resistance are realized by containing at least an aluminum phosphate as a metal phosphate and forming a dense insulating coating. becomes possible.
[0018]
(b) In order to realize a dense insulating coating, it is necessary to polycrystallize aluminum phosphate crystals in a fine state. Therefore, it is important to reduce the crystallinity of aluminum phosphate.
[0019]
(c) On the other hand, if most of the aluminum phosphate is in an amorphous state, it will react excessively with moisture in the air, degrading the hygroscopic resistance.
[0020]
(d) From the above point of view, the crystallinity of aluminum phosphate is controlled within the range of 0.5 to 5.0%.
[0021]
(e) In order to keep the crystallinity of aluminum phosphate within the above range, the composition and content of the organic resin and water-soluble organic compound to be contained together with the metal phosphate in the surface treatment agent, and the surface It is necessary to comprehensively control the heating conditions after applying the treatment agent.
[0022]
The present invention has been made based on the above findings. Each requirement of the present invention will be described below.
[0023]
1. Overall structure of non-oriented electrical steel sheet
FIG. 1 is a schematic diagram for explaining the structure of the non-oriented electrical steel sheet according to this embodiment. The non-oriented electrical steel sheet 1 includes a base material steel sheet 11 and an insulating coating 13 formed on the surface of the base material steel sheet 11 . In FIG. 1 , insulating coating 13 is provided on both surfaces in the thickness direction of base steel plate 11 , but insulating coating 13 may be provided only on one surface of base steel plate 11 .
[0024]
2. About the base material steel plate
The steel type of the base material steel sheet 11 used for the non-oriented electrical steel sheet 1 is not particularly limited. For example, it is preferable to use a non-oriented electrical steel sheet having a chemical composition containing, by mass %, Si: 0.1% or more, Al: 0.05% or more, and the balance being Fe and impurities.
[0025]
Si is an element that increases electrical resistance and improves magnetic properties when the content is 0.1% by mass or more. As the Si content increases, the magnetic properties also improve, but the brittleness tends to increase as the electrical resistance increases. Since the increase in brittleness becomes remarkable when the Si content exceeds 4.0% by mass, the Si content is preferably 4.0% by mass or less.
[0026]
As with Si, Al is also an element that increases electrical resistance and improves magnetic properties when the content is 0.05% by mass or more. As the Al content increases, the magnetic properties also improve, but the rollability tends to decrease at the same time as the electrical resistance increases. The deterioration of the rollability becomes remarkable when the Al content exceeds 3.0% by mass, so the Al content is preferably 3.0% by mass or less.
[0027]
As long as it is a non-oriented electrical steel sheet having the Si content and the Al content as described above, it is not particularly limited, and various known non-oriented electrical steel sheets can be used as the base material steel sheet 11. is.
[0028]
In addition to the above Si and Al, the base material steel plate 11 can contain Mn in the range of 0.01 to 3.0% by mass in place of part of the remaining Fe. In addition, in the base steel sheet according to the present embodiment, the total content of other elements such as S, N, and C is preferably less than 100 ppm, more preferably less than 30 ppm.
[0029]
In the present embodiment, a steel ingot (for example, a slab) having the above chemical composition is hot-rolled into a hot-rolled sheet and wound into a coil, and if necessary, the hot-rolled sheet is heated to a temperature range of 800 to 1050 ° C. It is preferable that the base material steel plate 11 is annealed at a temperature of 0.15 mm to 0.50 mm, then cold-rolled to a thickness of 0.15 to 0.50 mm, and further annealed. More preferably, the plate thickness of the base material steel plate 11 is 0.25 mm or less. Further, when annealing after cold rolling, the annealing temperature is preferably in the range of 750 to 1000°C.
[0030]
Further, in the base material steel plate 11, it is preferable that the surface roughness is relatively small, because the magnetic properties are improved. Specifically, the arithmetic mean roughness (Ra) in the rolling direction and in the direction perpendicular to the rolling direction is preferably 1.0 μm or less, more preferably 0.1 to 0.5 μm. preferable. This is because when Ra exceeds 1.0 μm, there is a tendency for the magnetic properties to deteriorate.
[0031]
3. Insulating coating
The insulating coating 13 is formed on at least one surface of the base steel plate 11 . The insulating coating is a chromium-free insulating coating containing metal phosphate, an organic resin, and a water-soluble organic compound, which will be described in detail below, as main components. Specifically, the total amount of metal phosphate, organic resin and water-soluble organic compound is 50 mass % or more based on the total mass of the insulating coating. Each component will be described in detail below.
[0032]
3-1. Phosphate metal salt
The metal phosphate contained in the insulating coating is a solid content when a solution (for example, an aqueous solution) containing phosphoric acid and metal ions as main components is dried, and is used as a binder in the insulating coating. It works. The type of phosphoric acid is not particularly limited, and various known phosphoric acids can be used. For example, it is preferable to use orthophosphoric acid, metaphosphoric acid, polyphosphoric acid, and the like. Also, a solution of a metal phosphate can be prepared by mixing at least one of metal ion oxides, carbonates, and hydroxides with various types of phosphoric acid.
[0033]
The metal phosphate contains aluminum (Al) as a metal element. That is, the insulating coating contains a metal phosphate of Al (that is, aluminum phosphate). The content of aluminum phosphate is not particularly limited, but it is preferable that 10 parts by mass or more of 100 parts by mass of the metal phosphate be aluminum phosphate.
[0034]
Further, in the non-oriented electrical steel sheet according to the present invention, when the insulating coating is measured by X-ray diffraction, the crystal of aluminum phosphate calculated from the peak attributed to the metal phosphate degree of conversion is in the range of 0.5 to 5.0%. Here, the degree of crystallinity is an index of 100% when all aluminum phosphate is crystallized, and 0% when all of it is amorphous. In the insulating coating according to the present embodiment, the fact that the degree of crystallinity of aluminum phosphate is within the range of 0.5 to 5.0% means that aluminum phosphate is only slightly crystallized and amorphous ( It means that it exists in a state close to amorphous).
[0035]
When the degree of crystallinity of aluminum phosphate exceeds 5.0%, the unevenness of the crystal plane of the crystallized aluminum phosphate becomes remarkable, resulting in a decrease in the space factor and deterioration in adhesion and/or workability. It will decline. However, if the crystallinity of the aluminum phosphate is excessively low and is less than 0.5%, the bonds of the metal phosphate will be in a state of surplus, and by bonding with water, moisture absorption will proceed, resulting in resistance to Hygroscopicity deteriorates.
[0036]
Al phosphate By controlling the crystallinity of aluminum within the range of 0.5 to 5.0%, the crystals of aluminum phosphate are polycrystallized in a fine state, making it possible to realize a dense insulating coating. Insulation, punchability, adhesion, hygroscopic resistance, corrosion resistance, and heat resistance are realized by realizing a dense insulating coating. The crystallinity of aluminum phosphate is preferably 4.0% or less, more preferably less than 2.0%, and even more preferably 1.0% or less.
[0037]
The crystallinity of aluminum phosphate can be controlled within a desired range by introducing a factor that suppresses the growth of crystal grains into the insulating coating. Crystallization is often suppressed when metal phosphates similar to each other are present in the insulating coating.
[0038]
Therefore, the metal phosphate preferably contains a divalent metal element M other than aluminum in addition to Al. Examples of such a divalent metal element M include one or more selected from the group consisting of Zn, Co, Mg, Mn, and Ni.
[0039]
By containing the metal phosphate containing the metal element M as described above in addition to aluminum phosphate as the metal phosphate, the crystallized region of the aluminum phosphate in the insulating coating can be suppressed to be small. As a result, it becomes possible to further polycrystallize the aluminum phosphate, and the insulating coating becomes more dense. In the insulating coating according to the present embodiment, the metal phosphate more preferably contains aluminum and zinc as metal elements (in other words, includes aluminum phosphate and zinc phosphate).
[0040]
Next, with reference to FIGS. 2 and 3, a method for specifying the degree of crystallinity of aluminum phosphate will be specifically described. FIG. 2 is an example of the XRD spectrum of the non-oriented electrical steel sheet according to this embodiment, and FIG. 3 is a schematic diagram for explaining the degree of crystallinity of the insulation coating.
[0041]
Fig. 2 shows the XRD spectrum of a non-oriented electrical steel sheet having aluminum phosphate, which is an example of a metal phosphate, as an insulating coating. As shown in FIG. 2, when the XRD spectrum of the non-oriented electrical steel sheet containing aluminum phosphate was measured, three strong peaks attributed to Fe in the base steel sheet were observed at 2θ=40 degrees, 60 degrees, and 80 degrees. A weak peak attributed to aluminum phosphate is observed near 2θ=20 degrees. The XRD peak of the metal phosphate varies depending on the metal element contained in the metal phosphate. The XRD peak of the metal phosphate of interest in this embodiment is observed, for example, near the following angles.
Aluminum phosphate: (2θ) around 21.59 degrees
[0042]
When the peak attributed to aluminum phosphate is enlarged, it is schematically shown in FIG. The peak of aluminum phosphate is a background due to diffraction by air etc. (part corresponding to area intensity A 0 in FIG. 3) and a broad peak due to amorphous metal phosphate ( A portion corresponding to area intensity A a) and a peak due to aluminum phosphate in a crystalline state (a portion corresponding to area intensity A c1 + A c2 in FIG. 3).
[0043]
In the schematic diagram above, there are two peaks for the sake of simplification, but in reality there are many peaks due to aluminum phosphate. Among them, only peaks with sufficiently high intensity need to be extracted. That is, the crystallinity W c (%) of aluminum phosphate can be calculated by the following formula (101).
[0044]
[Number 1]

[0045]
Here, the XRD spectrum of the non-oriented electrical steel sheet can be obtained by performing measurement using a commercially available X-ray diffractometer, and the measurement conditions are not particularly limited. An XRD spectrum of a non-oriented electrical steel sheet can be obtained by performing measurement under the following measurement conditions. That is, using a SmartLab device manufactured by RIGAKU Co., Ltd., Cu tube, voltage 40 kV, current 30 mA, measurement accuracy (2θ) 5 to 90 °, step 0.02 °, scan mode 4 ° / min, incident slit 1/2 deg take measurements.
[0046]
3-2. organic resin
The organic resin contained in the insulating coating exists in a dispersed state in the metal phosphate that functions as a binder. The presence of the organic resin in the metal phosphate suppresses the growth of large grains of the metal phosphate, making it possible to promote the polycrystallization of the metal phosphate, resulting in a dense insulation. It becomes possible to form a film.
[0047]
In order to sufficiently exhibit the effect of suppressing the growth of crystal grains of aluminum phosphate, the SP value of the organic resin should be within the range of 18.0 (MPa) 0.5 or more and 24.0 (MPa) 0.5 or more. . Although it depends on the baking conditions, in general, when the SP value of the organic resin is too low, it tends to separate from the metal phosphate. As a result, the metal phosphate tends to crystallize, and the crystallinity of aluminum phosphate increases. tends to be higher. On the other hand, when the SP value of the organic resin is too high, it tends to be easily mixed with the metal phosphate, the crystallization of the metal phosphate is significantly inhibited, and the crystallinity of the aluminum phosphate tends to excessively decrease. .
[0048]
The SP value of the organic resin is more preferably in the range of 19.0 (MPa) 0.5 or more and less than 23.5 (MPa) 0.5, still more preferably 20.0 (MPa) 0.5 It is within the range of 23.0 (MPa) or less than 0.5.
[0049]
Here, the SP value is called the solubility parameter. The solubility parameter used in the present invention is a thermodynamic physical quantity that represents a measure of compatibility between substances, and it is known that substances having similar SP values ​​tend to dissolve easily. The solubility parameter employed in the present invention is called Hildebrand's solubility parameter, and is generally measured by a method called the cloudiness method.
[0050]
In the cloudiness method, the organic resin is dissolved in advance in a solvent with a known SP value that dissolves the organic resin well, and another solvent with a known SP value that is different from that is gradually added dropwise, and the organic resin precipitates. The SP value of the organic resin is calculated from the amount of each solvent required until clouding and the SP value.
[0051]
The type of organic resin is not particularly limited as long as the SP value is within the above range, and includes acrylic resin, polystyrene resin, vinyl acetate resin, epoxy resin, polyurethane resin, polyamide resin, phenol resin, melamine resin, One or more of various known organic resins such as silicone resin, polypropylene resin, polyethylene resin, etc. can be used.
[0052]
Among them, it is preferable to use acrylic resin. More specifically, the acrylic resin is prepared by covalently combining an acrylic resin monomer or oligomer in the presence of a nonionic surfactant (which can also be considered as a reactive emulsifier) ​​having a radically polymerizable unsaturated group in the molecule. It is obtained by polymerization (more specifically, emulsion polymerization). In this embodiment, for example, a dispersion (emulsion) in which the obtained acrylic copolymer is dispersed in a dispersion medium such as water is used.
[0053]
Examples of the above nonionic surfactants include, for example, (meth)allyl groups, (meth)acrylic groups, styryl groups and the like having a radically polymerizable unsaturated group, and having an alkylene oxide addition mole number of 20 to 55. Surfactants within the range can be used singly or in combination of two or more. By using such an acrylic resin as an organic resin, it is possible to more reliably promote polycrystallization of the metal phosphate, and to realize a denser insulating coating.
[0054]
The monomer for the acrylic resin copolymer used in the present embodiment is not particularly limited, but examples include methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, n-octyl acrylate, i- Octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-dodecyl acrylate, and the like can be used. In addition, it is possible to use acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, etc. as monomers having a functional group. Hydroxylethyl (meth)acrylate, 2-hydroxylpropyl (meth)acrylate, 3-hydroxylbutyl (meth)acrylate, 2-hydroxylethyl (meth)allyl ether and the like can be used.
[0055]
The acrylic resin according to the present embodiment can be adjusted so that the SP value falls within a predetermined range by an emulsion polymerization method using the nonionic surfactant or by combining various monomers.
[0056]
3-3. water-soluble organic compound
The water-soluble organic compounds contained in the insulating coating are water-soluble organic compounds such as alcohols, esters, ketones, ethers, carboxylic acids, sugars, etc., and are compatible with inorganic composition liquids such as metal phosphates. be. By blending the water-soluble organic compound with the treatment liquid containing the metal phosphate and the organic resin, when the treatment liquid is applied to the surface of the steel sheet and dried, the water-soluble organic compound is added to the metal phosphate and the like. It becomes contained in the inorganic component. Incidentally, the term "water-soluble" as used in the present embodiment means a characteristic of being infinitely soluble or partially soluble in water.
[0057]
The water-soluble organic compound used in the present embodiment is a water-soluble organic compound having an SP value within the range of 19.0 (MPa) 0.5 or more and 35.0 (MPa) less than 0.5. Although it depends on the baking conditions, in general, when the SP value of the water-soluble organic compound is too high, the stability of the metal ions in the metal phosphate increases, resulting in the metal phosphate being more likely to crystallize, and the phosphate to become more stable. The crystallinity of aluminum tends to increase. On the other hand, when the SP value of the water-soluble organic compound is too low, the stability of the metal phosphate is lowered, and the crystallization of the metal phosphate is significantly inhibited, resulting in the formation of aluminum phosphate. crystallinity tends to decrease excessively.
[0058]
The SP value of the water-soluble organic compound is more preferably in the range of 20.0 (MPa) 0.5 or more and 34.5 (MPa) less than 0.5, still more preferably 24.0 (MPa) It is within the range of 0.5 or more and 34.0 (MPa) and less than 0.5.
[0059]
Specific examples of the water-soluble organic compound according to the present embodiment include ethyl diglycol acetate, n-butanol, ethyl acetate, propylene glycol monomethyl ether acetate, ethyl cellosolve, ethylene glycol monophenyl ether, pentanediol, isopropanol, 1, 3-pentanediol, allyl alcohol, acetonitrile, 1-pyropanol, tetrahydro 2,4-dimethylthiophene 1,1-dioxide, diethylene glycol, dimethylformamide, ethylacetamide, ethylenediamine, diethylsulfone, dimethyl phosphite, phenylhydrazine, 2- Methoxyethanol, butyrolactone, propylene glycol, ε-caprolactam, ethanol, 3-methylsulfolane, N-nitrosodimethylamine, propiolactone, tetramethylenesulfone, methylethylsulfone, 2-piperidone, phenol, dimethylsulfoxide, methanol, ethylene glycol , methylacetamide, 2-pyrrolidine, ethylene cyanohydrin, NN-dimethylformamide, glycerin and the like can be used.
[0060]
Among them, isopropanol, acetonitrile, diethylene glycol, ethylenediamine, 2-methoxyethanol, propylene glycol, ethanol, methanol, ethylene glycol, NN-dimethylformamide, glycerin and the like are suitable as the water-soluble organic compound according to the present embodiment.
[0061]
Also , the water-soluble organic compounds remain in the coating after coating and baking. At this time, even if the boiling point or sublimation point of the water-soluble organic compound is lower than the boiling point of water, the water-soluble organic compound and the metal phosphate interact with each other. remains in the film after coating and baking. In addition, since the time required for drying and baking the film is about several seconds during actual operation, the water-soluble organic compound remains in the film also from this point of view.
[0062]
However, in order to ensure that the water-soluble organic compound remains in the film after coating and baking, it is preferable that the boiling point of the water-soluble organic compound is higher than the boiling point of water if it is liquid, and the sublimation point if it is solid. More preferably, the water-soluble organic compound according to this embodiment has a boiling point or sublimation point of 150° C. or higher, more preferably 200° C. or higher. By using a water-soluble organic compound having a boiling point or sublimation point of 150° C. or higher, a reduction in the residual rate of the water-soluble organic compound in the film is suppressed, and the addition effect of the water-soluble organic compound is more reliably expressed. becomes possible. On the other hand, the boiling point or sublimation point of the water-soluble organic compound according to this embodiment is preferably less than 300°C. If the boiling point or sublimation point of the water-soluble organic compound is 300° C. or higher, it may cause stickiness and deliquescence.
[0063]
4. Insulating film thickness
The thickness of the insulating coating is, for example, preferably about 0.3-5.0 μm, more preferably about 0.5-2.0 μm. By setting the film thickness of the insulating coating within the above range, it is possible to maintain more excellent uniformity.
[0064]
5. Manufacturing method of non-oriented electrical steel sheet
A method for manufacturing a non-oriented electrical steel sheet according to the present embodiment is a manufacturing method for manufacturing a non-oriented electrical steel sheet including a base steel sheet and an insulating coating. The manufacturing method according to the present embodiment includes a step of applying a surface treatment agent to the surface of a base steel plate, and a step of heating the base steel plate coated with the surface treatment agent to form an insulating coating. include. Each step will be explained.
[0065]
5-1. Coating process of surface treatment agent
In the coating step, a surface treatment agent containing 3 to 50 parts by mass of an organic resin, 5 to 50 parts by mass of a water-soluble organic compound, and water as a solvent is applied to 100 parts by mass of a metal phosphate containing at least aluminum. Apply to the surface of the steel plate. The mixing ratio of the metal phosphate, the organic resin, and the water-soluble organic compound in the surface treatment agent is the mixing ratio of the metal phosphate, the organic resin, and the water-soluble organic compound in the insulating film after coating and drying.
[0066]
Here, the aforementioned metal phosphate, organic resin and water-soluble organic compound are used as the metal phosphate, organic resin and water-soluble organic compound in the surface treatment agent.
[0067]
The content of the organic resin contained in the surface treatment agent is 3 to 50 parts by mass with respect to 100 parts by mass of the metal phosphate. By setting the content of the organic resin to 3 parts by mass or more, the degree of crystallinity of aluminum phosphate can be made 5.0% or less. Also, by setting the content of the organic resin to 50 parts by mass or less, the degree of crystallinity of the aluminum phosphate can be made 0.5% or more. Moreover, by setting the content of the organic resin to 50 parts by mass or less, the concentration of the metal phosphate can be relatively increased, and heat resistance can be ensured.
[0068]
The content of the organic resin is preferably 5 parts by mass or more, more preferably 6 parts by mass or more, relative to 100 parts by mass of the metal phosphate. Also, the content of the organic resin is preferably 40 parts by mass or less, more preferably 25 parts by mass or less, relative to 100 parts by mass of the metal phosphate.
[0069]
Also, the content of the water-soluble organic compound contained in the surface treatment agent is 5 to 50 parts by mass with respect to 100 parts by mass of the metal phosphate. By setting the content of the water-soluble organic compound to 5 parts by mass or more, the degree of crystallinity of aluminum phosphate can be made 5.0% or less. Also, by setting the content of the water-soluble organic compound to 50 parts by mass or less, the degree of crystallinity of aluminum phosphate can be made 0.5% or more.
[0070]
In addition, by setting the content of the water-soluble organic compound to 5 parts by mass or more, punchability is also improved. Furthermore, by setting the content of the water-soluble organic compound to 50 parts by mass or less, the insulating coating is prevented from becoming sticky or cloudy, and a glossy coating surface can be obtained. The content of the water-soluble organic compound is preferably 6 parts by mass or more, more preferably 7 parts by mass or more, relative to 100 parts by mass of the metal phosphate. Also, the content of the water-soluble organic compound is preferably 40 parts by mass or less, more preferably 25 parts by mass or less, relative to 100 parts by mass of the metal phosphate.
[0071]
The surface treatment agent may further contain a nonionic surfactant. At this time, the content of the nonionic surfactant is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the metal phosphate. By setting the content of the nonionic surfactant to 0.1 parts by mass or more, it is possible to further stabilize the treatment liquid. Therefore, when a nonionic surfactant is contained, the content of the nonionic surfactant is more preferably 0.3 parts by mass or more, more preferably 0.3 parts by mass or more, with respect to 100 parts by mass of the metal phosphate. It is 5 parts by mass or more. On the other hand, when the content of the nonionic surfactant is 10 parts by mass or less, deterioration in corrosion resistance can be prevented. Therefore, when a nonionic surfactant is contained, the content of the nonionic surfactant is more preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the metal phosphate. is.
[0072]
Further, in the present embodiment, in addition to the above components, for example, inorganic compounds such as carbonates, hydroxides, oxides, titanates, tungstates, antifoaming agents, viscosity modifiers, preservatives agents, leveling agents, other brightening agents, etc. may be contained.
[0073]
Furthermore, in the emulsion polymerization, for example, persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide and p-menthane hydroperoxide , hydrogen peroxide and the like can be used. These polymerization initiators can be used singly or in combination. These polymerization initiators are preferably used in an amount of about 0.1 to 1 part by mass with respect to 100 parts by mass of the monomer.
[0074]
The surface treatment agent having the above ingredients is applied to the surface of the base steel sheet by various known application methods. The application method used here is not particularly limited, and a roll coater method, a spray method, a dip method, or the like may be used.
[0075]
5-2. Insulating coating formation process
In the insulating coating forming process, the insulating coating is formed by heating the base steel plate coated with the surface treatment agent to a predetermined heating temperature. The crystallinity of aluminum phosphate largely depends on the heating conditions. Therefore, it is necessary to optimize the heating conditions according to the composition of the surface treatment agent.
[0076]
The degree of crystallinity of aluminum phosphate can be determined by allowing the surface treatment agent applied to the surface of the base steel sheet to pass through a predetermined temperature range in a short period of time where crystals of metal phosphate begin to precipitate when drying and solidifying. can be reduced. Therefore, in particular, heating is performed so that the heating rate in the range of 100 to 200° C. is within the range of 10 to 100° C./sec.
[0077]
In addition, the lower the heating temperature, the lower the crystallinity, and the higher the heating temperature, the higher the crystallinity. Therefore, the heating temperature is set to 200 to 360.degree. In addition, by setting the heating temperature to 200° C. or higher, the polymerization reaction of the metal phosphate proceeds efficiently, making it easier to obtain water resistance and the like. On the other hand, by setting the heating temperature to 360° C. or lower, oxidation of the organic resin can be suppressed and productivity can be improved. The temperature at the start of heating is not particularly limited as long as it is around room temperature.
[0078]
Furthermore, by reducing the holding time at the above heating temperature, it is possible to reduce the crystallinity of aluminum phosphate. Therefore, the holding time at the heating temperature is set to 20 seconds or less. When the metal phosphate does not contain a divalent metal element M other than Al, crystallization is difficult to suppress, so the holding time at the heating temperature is set to less than 10 seconds.
[0079]
Then, the cooling rate from the heating temperature to 100°C is set within the range of 10 to 50°C/second. By setting the cooling rate to 10° C./second or more, it is possible to control the degree of crystallinity of aluminum phosphate to 5.0% or less. If the metal phosphate does not contain a divalent metal element M other than Al, crystallization is difficult to suppress, so the cooling rate is set to 20° C./second or more. On the other hand, by setting the cooling rate to 50° C./sec or less, the crystallinity of aluminum phosphate can be 0.5% or more.
[0080]
The heating method for carrying out the above heating is not particularly limited, and a normal radiant furnace or hot air furnace can be used, and heating using electricity such as an induction heating method is used. may
[0081]
The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
Example
[0082]
In this example, the chemical composition contained Si: 3.1%, Al: 0.6%, Mn: 0.2%, and the balance was Fe and impurities, and the plate thickness was 0.2%. A base steel plate having a diameter of 30 mm and an arithmetic mean roughness Ra of 0.32 μm was used.
[0083]
A treatment liquid having the composition shown in Table 1 was applied to the surface of the base steel plate so that the coating amount was 1.0 g/m 2 , and then baked under the conditions shown in Table 2. The types and SP values ​​of the water-soluble organic compounds and organic resins shown in Table 1 are as shown in Tables 3 and 4. In addition, the heating rate in Table 2 means the average heating rate from 100 ° C. to 200 ° C., the holding time means the time held at the heating temperature, and the cooling rate is from the heating temperature to 100 ° C. means the average cooling rate of
[0084]
[table 1]

[0085]
[Table 2]

[0086]
[Table 3]

[0087]
[Table 4]

[0088]
Metal phosphates are obtained by mixing and stirring orthophosphoric acid and metal hydroxides, oxides, and carbonates such as Al(OH) 3, ZnO, and Mg(OH) 2 , and then treating each phosphorous metalate. A liquid was prepared and made into a 40% by mass aqueous solution. All reagents used are commercially available. In Table 1, the amount of aluminum phosphate blended in the metal phosphate and the amount of other metal phosphate blended in the metal phosphate are shown in parts by mass.
[0089]
Commercially available water-soluble organic compounds and organic resins are also used, and have SP values ​​shown in Tables 3 and 4, respectively.
[0090]
The mixing ratio of the metal phosphate, the water-soluble organic compound and the organic resin in the treatment liquid shown in Table 1 is the same as the mixing ratio of the metal phosphate, the water-soluble organic compound and the organic resin in the insulating film after coating and drying. Become.
[0091]
Each sample of the obtained non-oriented electrical steel sheet was measured by the X-ray diffraction method to obtain the degree of crystallinity of aluminum phosphate. The XRD spectrum measurement conditions are as described above.
[0092]
In addition, various evaluation tests were conducted for each sample. The method for evaluating the manufactured samples will be described in detail below.
[0093]
Adhesion was evaluated by winding a steel plate sample with an adhesive tape attached to a metal rod having a diameter of 10 mm, 20 mm, and 30 mm, peeling off the adhesive tape, and evaluating the adhesion from the traces of peeling. Those that did not peel off even when bent at 10 mmφ were rated "A", those that did not peel off at 20 mmφ were rated "B", those that did not peel off at 30 mmφ were rated "C", and those that peeled off were rated " D”. Regarding the adhesiveness, those with grades A and B were regarded as acceptable.
[0094] Based on the interlayer resistance measured according to the JIS method (JIS C2550-4: 2019), the insulation is rated "D" for less than 5 Ω·cm 2 /sheet, 5 Ω·cm 2 /sheet or more and 10 Ω·cm 2/sheet Less than 10 Ω·cm 2 /sheet or more and less than 50 Ω·cm 2 /sheet was graded "B", and 50 Ω·cm 2 /sheet or more was graded "A". Regarding insulation, samples with grades A and B were regarded as acceptable.
[0095]
The heat resistance was evaluated by the corrosion resistance after strain relief annealing. Heat treatment was performed in a 100% nitrogen atmosphere at 850°C for 1 hour, followed by 48 hours in a constant temperature and humidity chamber at a temperature of 50°C and a humidity of 90%. The area ratio was evaluated. The evaluation criteria are as follows: "A" for grades 9 and 10, "B" for grades 6, 7, and 8, "C" for grades 4 and 5, and "D" for grades 1, 2, and 3. Those with grades A and B were regarded as acceptable.
[0096]
For workability, the cutting load of the sample was measured and used as an index of workability. A sample processed to 3 cm×6 cm was set so that a cutting blade was perpendicular to the sample, and the load when the sample was cut was measured. "A" indicates that the cutting load ratio is less than 0.95, "B" indicates that it is 0.95 or more and less than 1.00, and 1.00 or more. "C" is less than 1.05, "D" is from 1.05 to less than 1.10, and "E" is 1.10 or more. With respect to workability, those with grades A and B were regarded as acceptable.
[0097]
Corrosion resistance was evaluated according to the JIS salt spray test (JIS Z2371:2015). Specifically, a step of spraying a 5% NaCl aqueous solution on the sample in an atmosphere of 35 ° C. for 1 hour, a step of holding for 3 hours in an atmosphere of 60 ° C. and 40% humidity, and a step of holding the sample in an atmosphere of 40 ° C. and 95% humidity. A step of holding the sample for 3 hours in an atmosphere of 100° C. was defined as one cycle. Evaluation criteria are as follows. With respect to corrosion resistance, a rating of 5 or higher was considered acceptable.
[0098]
10: No rust occurred
9: Very little rust generation (area ratio of 0.10% or less)
8: Rusted area ratio = more than 0.10% and 0.25% or less
7: Rust generated area ratio = more than 0.25% and 0.50% or less
6: Rusted area ratio = more than 0.50% and 1.0% or less
5: Rusted area ratio = more than 1.0% and 2.5% or less
4: Rusted area ratio = more than 2.5% and 5.0% or less
3: Rusted area ratio = more than 5.0% and 10% or less
2: Area ratio with rust = more than 10% and 25% or less
1: Area ratio with rust = more than 25% and 50% or less
[0099]
Moisture absorption resistance was evaluated by visually determining the area ratio of rust generated on the surface after exposure for 720 hours in a constant temperature and humidity chamber adjusted to a temperature of 50 ° C and a humidity of 90%. Evaluation criteria are as follows. A rating of 3 or more was considered acceptable as moisture absorption resistance.
[0100]
5: No rust or very little rust (area ratio of 0.10% or less)
4: Rust generated area ratio = more than 0.10% and 0.50% or less
3: Rusted area ratio = more than 0.50% and 2.5% or less
2: Rusted area ratio = more than 2.5% and 10% or less
1: Area ratio with rust = more than 10% and 50% or less
[0101]
Appearance is glossy, smooth and uniform with 5, below, glossy but slightly inferior uniformity is 4, slightly glossy and smooth but inferior uniformity is 3, glossy. A value of 2 was given when there was little, slightly poor smoothness and poor uniformity, and a rating of 1 was given when poor gloss, uniformity, and smoothness. With respect to appearance, a rating of 3 or higher was regarded as acceptable.
[0102]
In addition, for each sample, the thickness of the insulating coating was measured by an electromagnetic thickness gauge, and from the measured value of the insulating coating on each surface of the base steel plate and the thickness of the base steel plate (300 μm), the space factor (%) was calculated. Note that the space factor in this example is the space factor (%)={300 μm/(300 μm+2×d 1)}×100 using the film thickness d 1 (μm) of the insulating coating shown in FIG. can be calculated.
[0103]
The obtained results are summarized in Table 5.
[0104]
[Table 5]

[0105]
As is clear from Table 5, the samples of the invention examples satisfying the stipulations of the invention did not contain chromic acid compounds, and had better insulating properties, workability, adhesion, moisture absorption resistance, corrosion resistance, and heat resistance. It showed excellent properties. On the other hand, the samples of the comparative examples, which deviate from any of the provisions of the present invention, could not achieve properties that combine insulation, workability, adhesion, moisture absorption resistance, corrosion resistance and heat resistance.
Code explanation
[0106]
1. Non-oriented electrical steel sheet
11. Base material steel plate
13. insulating coating
The scope of the claims
[Claim 1]
A base material steel plate and an insulating coating formed on the surface of the base material steel plate,
The insulating coating contains a total of 50% by mass or more of a metal phosphate, an organic resin, and a water-soluble organic compound with respect to the total mass of the insulating coating,
The metal phosphate contains at least aluminum as a metal element,
The organic resin has an SP value within the range of 18.0 (MPa) 0.5 or more and 24.0 (MPa) less than 0.5,
The water-soluble organic compound has an SP value within the range of 19.0 (MPa) 0.5 or more and 35.0 (MPa) less than 0.5,
When the insulation film is measured by X-ray diffraction, the crystallinity of the aluminum phosphate calculated from the peak attributed to the metal phosphate is 0.5 to 5.0%. is
　Non-oriented electrical steel sheet.
[Claim 2]
The metal phosphate further contains a divalent metal element M other than aluminum as a metal element,
The non-oriented electrical steel sheet according to claim 1.
[Claim 3]
The metal element M is one or more selected from the group consisting of Zn, Co, Mg, Mn, and Ni.
The non-oriented electrical steel sheet according to claim 2.
[Claim 4]
The content of the organic resin is 3 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the metal phosphate.
The non-oriented electrical steel sheet according to any one of claims 1 to 3.