JPS6214589B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-dispersible electrodeposited insulating coating used for manufacturing electrodeposited insulated wires. A conventional method of insulating a long conductor is to immerse the conductor in insulating paint, squeeze it with a die or the like at the exit from the paint tank to a predetermined coating thickness, and then bake it. However, with this method, it is impossible to obtain the desired thickness of the insulating film unless the coating is applied and baked by dipping into a paint bath 5 to 10 times. Therefore, a new method has been developed in which a water-dispersed paint or a water-soluble paint is deposited on a conductor by electrophoretic coating to form a desired thickness of an insulating film in a single coating process. However, in the method using water-soluble paint, although the film formation property of the electrodeposited layer is generally good, as the film deposited layer becomes thicker, the electrical resistance of the deposited layer increases and the paint is deposited. There is a limit to the thickness of the film deposited layer, and the paint contains many dissociative groups to make it water-soluble, which deteriorates the film properties. On the other hand, the method using a water-dispersed paint deposits an electrodeposited layer with a considerable thickness and is considered to be an effective method for coating an insulating film, but the film-forming properties of the electrodeposited layer are poor and it is left as it is. Baking it has the disadvantage that cracks or unevenness are likely to occur on the surface of the film. Therefore, as a method for preventing cracks in this drying and curing step, it has been carried out to apply a film forming aid by some means such as a method using an organic solvent (for example, Japanese Patent Publication No. 45-31555). Generally, the method of applying this film-forming aid is as follows:
After a water-dispersed electrodeposition paint is deposited on a conductor by electrophoresis, an organic solvent is applied onto the deposited layer either as a liquid or as a vapor, depending on the type of organic solvent used. The film-forming properties of the electrodeposited layer differ, and the characteristics of the resulting wire film also depend on it. The organic solvent to be used is determined in consideration of its cost, boiling point, toxicity, etc. Generally, the organic solvent applied to the electrodeposited layer is a hydrophilic solvent that dissolves in the water contained in the electrodeposited layer and spreads uniformly inside the electrodeposited layer. The permeability into the deposited layer is affected by the condition of the electrodeposited layer, especially its water content, so it is necessary to control the water content of the electrodeposited layer to be appropriate when applying the organic solvent. There is. Therefore, when using a water-dispersed paint, the water content of the electrodeposited layer is 60 to 70% (wt%, It is known from past experience that the moisture content (same below) is good, and when the moisture content is lower than that, foaming and cracking are likely to occur in the resulting wire coating, and flow patterns and bumps will occur on the surface of the coating. However, when the water content is higher than that, there is a tendency for unevenness to occur in the wire coating due to the application of the organic solvent. As described above, the deposition state of the electrodeposited layer, which is an important point in the manufacturing process of electrodeposited insulated wire, is inevitably determined by the composition of the water-dispersed paint used, and it is extremely difficult to freely control it. be. However, the present inventors have overcome the above-mentioned drawbacks and have developed a water-dispersed electrodeposited paint in which the water content of the electrodeposited layer is appropriately adjusted to provide good film properties during electrodeposition coating. As a result of intensive research for the development, 100 parts (parts by weight, same hereinafter) of at least one selected from the group consisting of acrylonitrile and methacrylonitrile as component (A).
On the other hand, ethyl acrylate, propyl acrylate, isobutyl methacrylate and α
- 50 to 125 parts of at least one selected from the group consisting of methylstyrene and 11 to 25 parts of at least two selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, glycidyl methacrylate and ureido vinyl ether as component (C)
0.3 to 2.5% of at least one member selected from the group consisting of acetic acid, propionic acid, acrylic acid, and methacrylic acid is added to the electrodeposited insulating paint obtained by emulsion polymerization of the resin solid content of the paint. The inventors have discovered that the above object can be achieved by using the present invention, and have completed the present invention. That is, in the present invention, the above (A), (B) and
A water-dispersed electrodeposition paint obtained by emulsion polymerization of component (C) is used. At least one of acrylonitrile and methacrylonitrile is used as the component (A) to impart solvent resistance and chemical resistance to the resulting electrodeposited film. In addition, as component (B), ethyl acrylate, propyl acrylate, isobutyl methacrylate or α
-Methylstyrene, and one or more of them can be used as appropriate to impart flexibility to the resulting electrodeposited film and improve polymerization stability. Component (C) includes acrylic acid, methacrylic acid, glycidyl methacrylate, acrylamide, or ureido vinyl ether,
When two or more of these are used, a crosslinking group is introduced into the resulting coating resin, thereby imparting heat resistance to the resulting coating. In addition, the amount of the components (A), (B), and (C) used is 50 to 125 parts of the component (B) per 100 parts of the component (A).
11 to 25 parts of component (C) are used. If component (B) is used in less than the above amount per 100 parts of component (A), the polymerization stability and storage stability of the resulting electrodeposition coating will be poor; In this case, the resulting electrodeposited film will have poor solvent resistance and chemical resistance, both of which are unfavorable. In addition, if component (C) is used in an amount less than the above-mentioned amount relative to 100 parts of component (A), the resulting film will have poor heat resistance, and if it is used in an amount exceeding the above-mentioned amount, polymerization reaction will occur. The resin generated inside may aggregate,
In addition, the flexibility of the resulting electrodeposited film may be markedly deteriorated, which is not preferable. In addition, the water-dispersed electrodeposited insulating coating of the resin composition used in the present invention can be prepared by adding the components (A), (B), and (C) in water using a common polymerization initiator such as potassium persulfate, ammonium persulfate, peroxide, etc. It is obtained by emulsion polymerization using hydrogen, etc., and the usual emulsion polymerization method is applied to its production. The emulsifier was uniformly dissolved by stirring while passing gas, and then the above-mentioned (A), (B) and (C) components were added in the above-mentioned specific ratios, the temperature of the polymerization system was raised to 70°C, and then the system was The solution of the polymerization initiator was gradually added dropwise, and the reaction temperature was 65 to 75°C.
Emulsion polymerization for ~5 hours. In this way, the water-dispersible electrodeposited insulating coating used in the present invention can be easily obtained. In addition, the resin solid content of the paint is usually 15 to 15%.
It is preferable from the viewpoint of reaction operation or electrodeposition coating operation to charge and polymerize the above-mentioned components so that the amount is about 30%. However, even if the insulating paint obtained by emulsion polymerization as described above is used as it is for electrodeposition coating, the moisture content of the electrodeposited layer is low (generally 35 to 60% or less), so the film does not form during the baking process. Foaming and cracking occur, and no matter how much organic solvent that is a film-forming aid is applied to the electrodeposited layer, the film foams or cracks occur, making it impossible to obtain a good insulating film. . In the present invention, after the emulsion polymerization reaction is completed, the resin solid content of the water-dispersed electrodeposited insulating paint obtained by emulsion polymerization as described above is
By adding 0.3 to 2.5% of at least one of acetic acid, propionic acid, acrylic acid, and methacrylic acid, the electrodeposition coating can be deposited during the electrodeposition coating process of electric wires without impairing the storage stability of the electrodeposition coating. For electric wires, the moisture content of the electrodeposited layer is adjusted to a range of 60 to 70%, and a film with a good appearance and excellent electrical properties can be created without cracking or bumps in the film during the baking process. Electrodeposition paint can be obtained. As mentioned above, the amount of the organic acid added is 0.3 to 2.5% based on the resin solid content of the water-dispersed electrodeposited insulating paint, but if the amount of the organic acid added is less than 0.3%, If the effect of adjusting the water content of the electrodeposited layer is not sufficient and the water content cannot be adjusted within the range of 60 to 70%, and if the amount added is more than 2.5%, It has poor storage stability and impairs its electrodeposition properties, both of which are unfavorable. As described above, the water-dispersed electrodeposited insulating paint obtained by emulsion polymerization of the components (A), (B), and (C) to which a specific amount of the specific organic acid has been added has an electrodeposited layer. Forms a good film by applying a film-forming aid, and hardens by baking to prevent foaming, flow patterns, and
An insulating film with good appearance and electrical properties can be obtained without causing any bumps or the like. Next, the present invention will be specifically explained with reference to Examples. Comparative Example 1 In a water-dispersed electrodeposited insulating paint prepared by emulsion polymerization of 60 parts of acrylonitrile as the (A) component, 30 parts of ethyl acrylate as the (B) component, and 7 parts of acrylic acid and 3 parts of glycidyl methacrylate as the (C) component. A bare copper wire with a diameter of 1 mm is run at a linear speed of 20 m/min, and a DC voltage of 5 V is applied between the opposite electrode to form an electrodeposited layer (water content 50%). A formamide mist was applied at a temperature of 130°C and then cured by heating. The resulting insulating film had many spots and had a poor appearance. Its properties are shown in Table 1. Comparative Example 2 Water-dispersed electrodeposited insulating paint made by emulsion polymerization of 40 parts of methacrylonitrile as the (A) component, 50 parts of propyl acrylate as the (B) component, and 5 parts of methacrylic acid and 5 parts of acrylamide as the (C) component. 1mm diameter inside
A bare copper wire of The mist was applied at a temperature of 140°C and then cured by heating. The obtained insulating film had foaming and lumps, and had a poor appearance. Its properties are shown in Table 1. Example 1 0.8% acetic acid was added to the water-dispersed electrodeposition paint used in Comparative Example 1 based on the resin solid content of the paint, and the diameter
An insulated wire was produced in the same manner as in Comparative Example 1 except that a 0.5 mm bare copper wire was used. The moisture content of the electrodeposited layer is
64%, and the film obtained by heating and curing had no foaming, flow patterns, or lumps, had a good glossy surface, and exhibited excellent insulation performance. Its properties and evaluation results are shown in Tables 1 and 2.
Shown in the table. Example 2 2% acrylic acid was added to the water-dispersed electrodeposition paint used in Comparative Example 2 based on the resin solid content of the paint,
An insulated wire was produced in the same manner as in Comparative Example 2 except that a bare copper wire with a diameter of 0.5 mm was used. The moisture content of the electrodeposited layer is 69%, and the film obtained by heat curing has no bubbles, flow patterns, or lumps, has a good glossy surface, and exhibits excellent insulation performance. Ta. Its properties and evaluation results are shown in Tables 1 and 2. Example 3 and Comparative Example 3 52 parts of acrylonitrile as component (A), 28 parts of α-methylstyrene and 26 parts of ethyl acrylate as component (B), 3 parts of acrylamide as component (C),
Methacrylic acid was added in an amount of 0.4% based on the resin solid content of the paint to a water-dispersed electrodeposition paint in which 1 part of acrylic acid and 2 parts of glycidyl methacrylate were polymerized. A bare copper wire with a diameter of 0.5 mm is run at a linear speed of 20 m/min through the paint to which methacrylic acid has been added, and a DC voltage of 5 V is applied between it and the opposite electrode to form an electrodeposited layer (water content: 66 %) was formed, and ethyl cellosolve was applied in the form of steam, followed by heat curing. The resulting film was free from foaming, flow patterns, and lumps, had a good gloss, and exhibited excellent insulation performance. Its properties and evaluation results are shown in Tables 1 and 2. The moisture content of the electrodeposited layer without the addition of methacrylic acid was 49%, and the film heat-cured in the same manner as above had bumps and a running pattern on the surface. Example 4 and Comparative Example 4 51 parts of acrylonitrile as component (A), 25 parts of propyl acrylate and 16 parts of isobutyl methacrylate as component (B), and 5 parts of ureido vinyl ether and 3 parts of methacrylic acid as component (C) were polymerized. Propionic acid was added in an amount of 1.5% and acetic acid was added in an amount of 0.9% based on the resin solid content of the paint. A bare copper wire with a diameter of 0.5 mm was passed through the paint containing propionic acid and acetic acid at a wire speed of 20.
m/min, and applied a DC voltage of 5 V between the counter electrode to form an electrodeposited layer (water content 68%), and a mist of N・N-dimethylformamide was formed.
It was applied at a temperature of 130°C and then heat cured. The obtained insulating film was free from foaming, flow patterns, or lumps, had a good gloss, and exhibited excellent insulating performance. Its properties and evaluation results are shown in Tables 1 and 2. In the case where propionic acid and acetic acid were added, the moisture content of the electrodeposited layer was 38%, and foaming was observed in the film heat-cured in the same manner as above.

【table】

[Table] Comparative Example 5 64 parts of acrylonitrile as component (A), 26 parts of ethyl acrylate as component (B), 7 parts of acrylic acid and 3 parts of glycidyl methacrylate as component (C) were polymerized. Polymerization stability was not very good. Acetic acid was added to the resulting water-dispersed electrodeposition paint in an amount of 0.8% based on the resin solid content of the paint. The storage stability of the paint was also not very good. A diameter of 0.5
A bare copper wire of 1.5 mm in diameter was run at a line speed of 20 m/min, and a DC voltage of 5 V was applied between it and the opposing electrode to form an electrodeposited layer, and N.N-dimethylformamide was applied as vapor. It was then heated and cured. The resulting film had a glaring appearance, a heat shock (200°C, 1 hr) of 4 times the diameter, and a breakdown voltage of 3.2 KV in glycerin. Comparative Example 6 Acetic acid was added to a water-dispersed electrodeposition paint made by polymerizing 38 parts of acrylonitrile as component (A), 52 parts of ethyl acrylate as component (B), and 5 parts of acrylic acid and 3 parts of glycidyl methacrylate as component (C). It was added in an amount of 0.8% based on the resin solid content of the paint. A diameter of 0.5
A bare copper wire of 1.5 mm in diameter was run at a line speed of 20 m/min, and a DC voltage of 5 V was applied between it and the opposing electrode to form an electrodeposited layer, and N.N-dimethylformamide was applied as vapor. It was then heated and cured. Although the resulting film had a good appearance, it had low heat resistance and a softening point (load of 2.5 kg) of 182°C. Furthermore, the solvent resistance and chemical resistance were also insufficient. Comparative Example 7 Acetic acid was added to a water-dispersed electrodeposition paint made by polymerizing 46 parts of methacrylonitrile as component (A), 50 parts of propyl acrylate as component (B), and 2 parts of methacrylic acid and 2 parts of acrylamide as component (C). was added in an amount of 0.8% based on the resin solid content of the paint. A diameter of 0.5
A bare copper wire of 1.5 mm in diameter was run at a line speed of 20 m/min, and a DC voltage of 5 V was applied between it and the opposing electrode to form an electrodeposited layer, and N.N-dimethylformamide was applied as vapor. It was then heated and cured. The resulting film had a softening point (load: 2.5 kg) of 165°C. Comparative Example 8 Acetic acid was added to a water-dispersed electrodeposition paint made by polymerizing 34 parts of methacrylonitrile as the (A) component, 35 parts of propyl acrylate as the (B) component, and 7 parts of methacrylic acid and 7 parts of acrylamide as the (C) component. was added in an amount of 0.8% based on the resin solid content of the paint. A diameter of 0.5
A bare copper wire of 1.5 mm in diameter was run at a line speed of 20 m/min, and a DC voltage of 5 V was applied between it and the opposing electrode to form an electrodeposited layer, and N.N-dimethylformamide was applied as vapor. It was then heated and cured. The resulting film had a diameter five times better when subjected to heat shock (200°C, 1 hr), and was a very brittle film. Comparative Example 9 Acrylic acid was added to a water-dispersed electrodeposition paint similar to that used in Example 4 at a ratio of 3.5% to the resin solid content of the paint.
% added. The paint had some problems with storage stability. The diameter of the paint to which acrylic acid has been added is
A 0.5 mm bare copper wire is run at a line speed of 20 m/min, and a 5 V DC voltage is applied between it and the opposing electrode to form an electrodeposited layer, and N/N-dimethylformamide is applied as vapor. After that, it was heated and cured. The resulting film had an uneven surface and a breakdown voltage of 2.1 KV in glycerin. Comparative Example 10 To a water-dispersed electrodeposition paint similar to that used in Example 4, carbolic acid (bp 181.7°C) was added in an amount of 2% based on the resin solid content of the paint. The diameter of the paint to which such carbolic acid has been added
A 0.5 mm bare copper wire is run at a line speed of 20 m/min, and a 5 V DC voltage is applied between it and the opposing electrode to form an electrodeposited layer, and N/N-dimethylformamide is applied as vapor. After that, it was heated and cured. The resulting film had bumps due to foaming. Comparative Example 11 Put 40 parts of ion-exchanged water into a flask, completely replace the dissolved oxygen in the ion-exchanged water through nitrogen gas, and then add 4 parts of acrylonitrile, 6 parts of ethyl methacrylate, 0.5 parts of methacrylic acid, and 0.1 part of lauryl sulfate ester soda. was added, the temperature was raised to 60°C, a redox catalyst consisting of 0.015 parts of potassium persulfate and 0.005 parts of sodium bisulfite was added, and emulsion copolymerization was carried out at 60 to 65°C for 5 hours in a nitrogen stream to form a water-dispersed varnish. I made it. The film obtained by electrodepositing this varnish on a bare copper wire with a diameter of 0.5 mm in the same manner as in Example 3 has a thickness of 30 μm.
m, the breakdown voltage in glycerin was 3.2KV. Comparative Example 12 Put 40 parts of ion-exchanged water into a reaction container, completely replace dissolved oxygen with nitrogen gas, and then add 3 parts of acrylonitrile, 1 part of vinyl acetate, 3 parts of isobutyl methacrylate, 3 parts of methyl methacrylate,
Add 0.3 parts of methacrylic acid and 0.1 part of lauryl sulfate ester soda, raise the temperature to 60°C, then add 0.015 parts of potassium persulfate and 0.005 parts of sodium bisulfite, and react at 65°C for 4 hours to form a water-dispersed varnish. Tsukutsuta. The film obtained by electrodepositing this varnish on a bare copper wire with a diameter of 0.5 mm in the same manner as in Example 3 has a thickness of 28 μm.
m, wear resistance is 20 times, softening point (load 2.5Kg) is 209
℃, the breakdown voltage in glycerin was 3.1KV. Comparative Example 13 Put 380 parts of ion-exchanged water into a reaction vessel, completely replace dissolved oxygen with nitrogen gas, and then add 10 parts of ethyl acrylate, 1 part of glycidyl methacrylate, 1 part of methacrylic acid, and 1 part of lauryl sulfate ester soda. After heating to 70℃, add a solution of 0.01 part of potassium persulfate and 0.03 part of sodium bisulfite dissolved in 10 parts of ion-exchanged water, and heat at 70℃ for 30 minutes.
After reacting for a minute, add 65 parts of acrylonitrile, α
- A mixed solution of 15 parts of methylstyrene, 4 parts of glycidyl methacrylate, and 4 parts of methacrylic acid was added dropwise, and after completion of the addition, a reaction was carried out to prepare a water-dispersed varnish. Using this varnish, an electrodeposited film with a thickness of 30 μm was formed on a bare copper wire with a diameter of 0.5 mm. The resulting film had a good appearance, but the breakdown voltage in glycerin was 3.1 KV. Comparative Example 14 A reaction vessel was charged with 350 parts of ion-exchanged water, 50 parts of acrylonitrile, 15 parts of α-methylstyrene, 20 parts of ethyl acrylate, 8 parts of N-methylolacrylamide, 7 parts of methacrylic acid, and 3 parts of sodium laurylbenzenesulfonate. After passing nitrogen gas for 30 minutes with stirring, potassium persulfate was added.
A solution prepared by dissolving 0.02 part of sodium bisulfite and 0.01 part of sodium bisulfite in 50 parts of ion-exchanged water was added and emulsion copolymerized at 70°C for 3 hours to obtain an electrodeposition water-dispersed varnish for electric wires. The obtained varnish was electrodeposited on a bare copper wire with a diameter of 0.5 mm in the same manner as in Example 3, and the electrodeposited film was immersed in N·N-dimethylformamide for a few seconds, then heated at 80°C for 30 minutes and at 180°C. After heating and curing for 3 hours, a 31 μm thick film with a uniform and good appearance was obtained. The softening point of the obtained film (load 2.5 kg) is 221℃,
The breakdown voltage in glycerin was 3.2KV. Comparative Example 15 Put 40 parts of ion-exchanged water into a flask, completely remove the dissolved oxygen in the ion-exchanged water by passing nitrogen gas, and then add 3 parts of ethyl acrylate, 2.5 parts of acrylonitrile, 1 part of vinyl acetate, and 1 part of methyl methacrylate. , 1 part of ethyl methacrylate, 1 part of n-butyl methacrylate, 1 part of methacrylic acid and 0.1 part of sodium lauryl sulfate were added, heated to 60°C, and then mixed with 0.015 part of potassium persulfate and 0.005 part of sodium sulfite. Add the redox polymerization catalyst and heat at 60 to 75℃ for 5 minutes while stirring in a nitrogen stream.
A time-emulsion copolymerized water-dispersed varnish was created. This varnish was electrodeposited onto a bare copper wire having a diameter of 0.5 mm in the same manner as in Example 3, and then baked at 100° C. for 3 hours. The resulting film with a thickness of ₂₈₁ μm had a good appearance, but the breakdown voltage in glycerin was 3.5 KV. As described above, the present invention provides the above-mentioned specific
By adding the specific organic acid in the specific ratio to the water-dispersed electrodeposition paint made by polymerizing components (A), (B), and (C), electrical and mechanical properties or chemical resistance can be improved. A water-dispersed electrodeposition coating that provides an extremely excellent insulating film can be obtained, and is extremely advantageous from an industrial perspective.

Claims (1)

[Claims] 1 Component (A) is 100 parts by weight of at least one selected from the group consisting of acrylonitrile and methacrylonitrile, and component (B) is ethyl acrylate, propyl acrylate, isobutyl methacrylate, and α-methylstyrene. Emulsion polymerization of 50 to 125 parts by weight of at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, glycidyl methacrylate, and 11 to 25 parts by weight of at least two selected from the group consisting of ureido vinyl ether as component (C). 0.3 to 2.5% by weight of at least one member selected from the group consisting of acetic acid, propionic acid, acrylic acid, and methacrylic acid is added to the electrodeposited insulating paint obtained by adding 0.3 to 2.5% by weight based on the resin solid content of the paint. Water-dispersed electrodeposited insulating paint.