JPH042779A - Treatment of electrically insulated organic film excellent in corrosion resistance and stabilized sliding property in silicon steel sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a treatment method for forming an all-organic electrical insulating film having excellent corrosion resistance and stable slip properties on an electrical steel sheet.

(Prior art) As is well known, when non-oriented electrical steel sheets are used in large rotating machines, etc., they are required to have high electrical insulation resistance to prevent eddy currents on the surface. The coating is easy to apply in a thick layer and provides high electrical insulation.

Further, since the iron core to be assembled into a motor or the like is assembled by punching out an electromagnetic steel sheet, it is important that the steel sheet having an insulating coating has good punchability.

The punchability of electrical steel sheets is influenced by many factors, one of which is the lubricity of the surface of electrical steel sheets, and it is known that applying an organic coating to the surface improves punchability. . In addition, organic coatings also have excellent adhesion.

Organic films are known, for example, from Japanese Patent Publication No. 5G-15538. Special Public Service No. 51-15538
The feature of the publication is that by mixing polyvinyl alcohol, styrene emulsion resin, and water-soluble acrylic resin in an appropriate blending ratio, heat resistance etc. are improved and baking at high temperature for a short time is possible.

(Problems to be Solved by the Invention) However, in recent years, non-oriented electrical steel sheets coated with organic coatings have also been required to have various properties.

For example, although organic coatings originally have good lubricity, the slipperiness of steel sheets is unstable. It is required to exhibit even and stable sliding properties on the guide.

Further, electrical steel sheets are required to have high corrosion resistance, but when an organic film is coated and baked on the surface of a non-oriented electrical steel sheet, pinholes are generated due to evaporation of the medium, resulting in poor corrosion resistance. Therefore, in order to obtain high corrosion resistance, multiple coatings are required, but multiple coatings require a large investment in equipment and increase costs, which is not practical.

The present invention forms an organic electrical insulating film on the surface of a non-oriented electrical steel sheet, which has excellent insulating properties as described above, improves corrosion resistance and slipperiness, and is also excellent in all other properties. The purpose is to provide a processing method.

(Means for Solving the Problems) The gist of the present invention for achieving the above object is as follows.

That is, 1 part by weight of a mixture of one or more of phenolic, epoxy, polyester, styrene, and acrylic resins and a particle size of 2! are applied to the surface of an electrical steel sheet.
! Spherical organic resin particles of n to 50ttra 0. O1~0
．． After applying a thin and uniform treatment liquid containing 5 parts by weight as a main component, baking is performed to obtain a surface roughness Ra (center line average roughness) of 0.
This is a method for treating an organic electrical insulation film with excellent corrosion resistance and stable slip properties on electrical steel sheets, which is characterized by forming a film with a thickness of 3 to 1.0 tna.

Hereinafter, the content of the present invention will be explained in detail.

[Organic resin used in the present invention]

The organic resin as used in the present invention is any one of phenolic, epoxy, polyester, styrene, and acrylic resins, or a mixture of two or more thereof. When using organic solvents, sufficient consideration must be given to safety, hygiene, and drying equipment.

Therefore, it is desirable to use a water-soluble resin or a water emulsion resin.

[Spherical organic resin particles used in the present invention] The organic resin particles used in the present invention are 2I! It is a spherical fine powder with a particle size in the range of n to 50 uts, and refers to a relatively regular shape with a smooth surface without angular surfaces, and a true spherical one is particularly desirable. This type of truly spherical organic resin particles is known, for example, from Japanese Patent Application Laid-open No. 60-2124.
It is obtained by the method disclosed in Japanese Patent No. 30.

The shape of organic resin particles conventionally used in electrical steel sheets is
As shown in the photo in Figure 2, they have an angular and irregular shape, whereas the optimal spherical organic resin particles used in the present invention have a very smooth surface as shown in the photo in Figure 2. It has a regular shape.

Examples of such spherical organic resin particles include polyethylene,
Polyolefins such as polypropylene, polyacrylics,
One or more copolymers or mixtures of polystyrene, polyamide, benzoguanamine, melamine, Bakelite, polyacrylonitrile, etc. are used.

In addition, the reason why the particle size of the spherical organic resin particles is limited from 2 to 50 mm is that if the particle size is less than 2 mm, an effective coating surface roughness cannot be obtained, and therefore sufficient slipperiness cannot be obtained. This is because corrosion resistance is not exhibited, and adhesion is poor at 50- or more.

[Blend ratio] The reason why the amount of spherical organic resin particles is limited to 0.01 to 0.5 parts by weight per 1 part by weight of water-soluble resin or water-dispersible emulsion resin is 0.01 to 0.5 parts by weight. This is because if it is less than 0.1, it is difficult to obtain a surface roughness that is effective for exhibiting sufficient sliding properties, and no improvement in corrosion resistance is observed, and if it is more than 0.5, the adhesion between the steel plate and the coating is poor. .

Although it is essential that the treatment liquid in the present invention contains the above-mentioned two components, a dispersibility improver such as a nonionic surfactant may also be added.

[Processing Law]

The mixing, application, and baking of the treatment liquid are methods, but after stirring the treatment liquid thoroughly, a prescribed amount is applied using a roll coater or spray method. Just attach it. If it is below 250°C, it may be necessary to bake for a long time.

[Amount of coating]

Next, the amount of insulating film to be formed on the surface of the electromagnetic steel sheet is not particularly limited, but may be in the range of Ig/rrf to 7g/d, or 1g/rrf to 7g/d.
/rri, sufficient punchability cannot be obtained;
If it exceeds rd, the space factor will be poor, which is not preferable.

[Surface roughness of film]

Surface roughness is 0.3 to 1.0 in Ra (center line average roughness)
limited to tln (approximately 1 to 4μ when expressed as μH7,8)
H□, 8). This is because if it is less than 0.3 ufo, it is difficult to ensure stable sliding properties, and if it is more than 1.0 ufo, there is a problem with the space factor.

[Surface condition of film]

When a treatment solution containing spherical organic resin particles is uniformly applied to the surface of an electrical steel sheet and baked, the organic particles exhibit a much better uniform dispersion than when conventional resin particles are used on the surface of the steel sheet. That is, because of the shape of the spherical organic resin particles, agglomeration in the solution is extremely difficult to occur, and an extremely excellent dispersion liquid can be obtained.

As a result, the spherical organic resin particles can be uniformly applied to the steel plate by any common coating method.

In other words, in the case of the truly spherical organic resin particles of the present invention as shown in the photograph in Figure 2, the particles do not aggregate in the film, as shown in the photograph in Figure 4, showing the structure of the surface of the film. Shows uniform dispersibility. On the other hand, when a treatment liquid containing organic particles, which has been conventionally used for electrical steel sheets, is applied to a steel plate and baked, as shown in the photograph in Figure 1, the film surface structure is shown in the photograph in Figure 3. As a result, organic particles agglomerate, making it impossible to obtain uniform surface roughness and density.

The photos in Figures 3 and 4 are taken at 450℃ x 60sec.
This shows the surface condition after baking.

[Stable sliding property]

The reason why stable slip properties can be obtained by the present invention is considered as follows. As already mentioned, conventional organic films have good lubricity, but when processed into iron cores, there is unevenness between the edges of each iron core, making it unstable on the guide during the processing of iron cores such as motors. No slipping.

On the other hand, according to the present invention, a predetermined surface roughness is provided,
In addition, when the organic particles are uniformly dispersed, the surface roughness and surface condition of the coating are controlled, and the surface condition of the steel sheet can be made extremely uniform.

As already mentioned, the particle size of the spherical organic resin particles used in the present invention is in the range of 2ρ to 501 m, and the amount added is 0.000 m/w per 1 part by weight of the water-soluble resin or water-dispersible emulsion resin. It is limited to 0.01 to 0.5 parts by weight.

Under these conditions, a surface condition with uniform and fine surface roughness and excellent slipperiness is obtained.

[Internal state of film]

When water-soluble resin or water-dispersible emulsion resin, which has been conventionally used for electrical steel sheets, is applied and baked on the surface of the steel sheet,
Evaporation of the medium causes pinholes or even cracks, resulting in poor corrosion resistance.

However, the coating formed by applying and baking a treatment solution containing 2 to 50 particles of spherical organic resin used in the present invention on a steel plate has no pinholes or cracks and has high corrosion resistance.

That is, when spherical organic resin particles of 2-50 um are added to a solution, they are uniformly dispersed in the solution. When this treatment liquid is applied to the surface of a steel plate and baked, as the temperature rises and the medium evaporates, the spherical organic resin particles melt and spread within the surface of the coating, thereby suppressing the occurrence of pinholes and the like. Therefore, high corrosion resistance can be obtained.

On the other hand, when adding nurturing resin particles that have been conventionally used for electrical steel sheets and have irregular surfaces with uneven surfaces as shown in the photograph in Figure 1, the particles do not disperse well in the treatment solution and agglomerate, resulting in steel sheets. Even when coated and baked, the organic particles are not uniformly dispersed within the surface of the film, resulting in coarse and dense organic particles, pinholes, etc. occur in areas where the organic particles are poorly distributed, and there is almost no improvement in corrosion resistance.

(Example) Next, examples and comparative examples of the present invention will be described.

The treatment solutions A to E were applied to the surface of an electrical steel sheet (2.0% S1 content, sheet thickness 0.5 mm, surface roughness Ra 0.22a), squeezed with a rubber roll, and then heated in an annealing furnace set at 450°C. Baked for 80 seconds.

Table 2 shows the results of the above examples and comparative examples.

(a): JIS 2 method (b) Nisteel die (SKD-1), clearance 5%, number of punches up to burr height 30 mm (c): JIS Z 2371 salt water spray 7 hou
r(d): A commercially available surface property measuring device was used to determine #j of slipperiness. The measurement conditions were a vertical load of 100. and φ10
The test was carried out using a mm alumina ball at a moving speed of 20 mm/see in the atmosphere. After repeated back-and-forth friction 10 times, samples with no peeling of the film or large scratches left on the surface were evaluated as passing samples.
Samples with visible flaws on the film were rejected.

(Effects of the Invention) As detailed above, according to the method of the present invention, it is possible to impart excellent corrosion resistance and stable slip properties to an organic film,
An electrical steel sheet having an organic electrical insulation film with excellent overall properties can be obtained.

[Brief explanation of drawings]

The photograph in Figure 1 is an electron microscope (1000x) shape photograph of organic resin particles used in the conventional surface treatment of non-oriented electrical steel sheets, and the photograph in Figure 2 is a photograph of the spherical organic resin particles used in the present invention. Electron microscope (1000x) shape photograph of resin particles, Part 3
The photographs in the figure and the photographs in FIG. 4 are electron microscope (300x) microstructure photographs of the film surface after baking using the organic resin particles shown in the photographs in FIG. 1 and the photograph in FIG. 2, respectively. As is clear from Table 2, according to this example, a film of electrical steel sheet having excellent corrosion resistance and stable slip properties was obtained. Note that all samples had good punchability and adhesion. Patent applicant Nippon Steel Corporation Sub-agent Patent attorney Hiroaki Tamura Figure 1 Figure 3 Figure 2 Figures -+

Claims (1)

[Claims] 1 part by weight of a mixture of one or more of phenolic, epoxy, polyester, styrene, and acrylic resins and a particle size of 2 μm to 50 μm are applied to the surface of the electrical steel sheet.
After applying a thin and uniform treatment solution containing 0.01 to 0.5 parts by weight of spherical organic resin particles of μm as a main component, the surface roughness is Ra (center line average roughness) of 0.3 μm to 1 μm. .0μ
A method for treating an organic electrical insulation film with excellent corrosion resistance and stable slip properties on an electrical steel sheet, which is characterized by forming a film of m.