JPS6143392B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-dispersed electrodeposition coating material. More specifically, the present invention relates to a water-dispersed electrodeposition coating that provides a good high-temperature electrical insulation film with improved continuous film formation. In general, electrodeposition coating methods have excellent features such as high paint usage efficiency, easy shortening or automation of the process, and the ability to obtain a uniform paint film without pinholes. Since it does not contain organic solvents, it has the advantage of having no adverse effects on health and safety. As an example of an electrodeposition paint used in such electrodeposition coating, a so-called water-soluble paint is known, in which a resin substance having a molecular weight of several thousand or less is dissolved in water in molecular form. This water-soluble paint can produce a uniform electrodeposited film on objects with complex shapes (good throwing power), but it can only produce a film with a thickness of several tens of microns at most. It has the advantage that thick film coating is not possible. Furthermore, since this water-soluble paint essentially dissolves in the water medium due to the dissociative groups that the resin has in its molecules, the resulting resin film inevitably has the disadvantage of poor electrical insulation. be. On the other hand, water-dispersed paints are another example of electrodeposition paints. Although these water-dispersed paints have lower throwing power than water-soluble paints, they can be used to insulate electrical equipment because they can be applied in thick films. Furthermore, since a high molecular weight resin is used, it has the advantage that a film with excellent insulation properties can be easily formed. Conventionally, methods for manufacturing insulated wires using this water-dispersed paint for electrodeposition coating have been known, but in this case, the electrodeposition film is either immersed in some kind of organic solvent or The method is to pass it through steam and then heat it to form a continuous film. However, as mentioned above, the use of organic solvents has health and safety issues.
Furthermore, the cost impact cannot be ignored. In addition, even with conventional water-dispersed paints, it is possible to form a continuous film without the above-mentioned treatment with an organic solvent by using water-dispersed particles that have a low minimum film-forming temperature. , when such a film is used as an insulating film,
It has drawbacks such as extremely poor high-temperature insulation properties. As a result of intensive research to eliminate the above-mentioned conventional drawbacks, the present inventors have discovered an electrodeposition paint that can form a continuous film without the need for an organic solvent after electrodeposition, and have completed the present invention. I've reached it. That is, the present invention provides at least 80 to 95% (by weight %, hereinafter the same) of at least two types of acrylonitrile selected from the group consisting of acrylonitrile, styrene, α-methylstyrene, methyl methacrylate, and vinyl acetate, as well as glycidyl methacrylate and methacrylic acid. and methacrylic acid selected from the group consisting of A polymer selected from the group consisting of a polymer that provides a minimum film formation temperature of 80°C or higher for dispersed particles (hereinafter referred to as a hard component), and ethyl acrylate and n-propyl methacrylate that can provide a minimum film formation temperature of 60°C or lower for water-dispersed particles through polymerization. at least two compounds containing 60-85% of at least one of the discovered compounds and methacrylic acid selected from the group consisting of glycidyl methacrylate, methacrylic acid and N-methylolacrylamide15
Regarding a water-dispersed electrodeposition paint comprising a copolymer obtained by graft copolymerization with 15 to 25 parts of a second organic compound (hereinafter referred to as a soft component) consisting of ~40%, this By using such a resin component, the minimum film formation temperature of water-dispersed particles in a varnish state is lowered, and the glass transition temperature of the final baked film is not lowered, so high-temperature insulation properties are maintained, and organic solvents are not required when forming a continuous film. can do. The hard components used in the present invention include acrylonitrile, styrene, methyl methacrylate, which is a compound that exhibits properties as a hard component,
80-95% of acrylonitrile of at least two of vinyl acetate and α-methylstyrene, and reactive monomers of glycidyl methacrylate, methacrylic acid and N-methylol acrylamide used to improve the properties of baked coatings. At least one type containing methacrylic acid 5 to 20
It is a polymer using %. The soft component is at least one of ethyl acrylate and propyl methacrylate, which are compounds that exhibit properties as a soft component.
It consists of 60-85% of a species and 15-40% of at least two reactive monomers used to improve the properties of the baked film, including methacrylic acid among methacrylic acid, glycidyl methacrylate and N-methylolacrylamide. It is necessary that the amount of the soft component used is 15 to 25 parts with respect to 100 parts of the first organic compound. If the amount of the soft component used is less than 15 parts, it will not be possible to sufficiently lower the minimum film forming temperature of the water-dispersed particles in the varnish state, making it difficult to form a continuous film without treatment with an organic solvent. Moreover, if it exceeds 25 parts, it will lower the glass transition temperature of the final baked film, making it difficult to maintain high-temperature insulation properties. When preparing the graft copolymer, a surfactant is usually used in combination. As the above-mentioned surfactant, anionic surfactants such as sodium lauryl sulfate, sodium lauryl benzenesulfonate, sodium oleyl sulfate, and sodium steering acid are preferably used in terms of electrodepositivity, but of course, It is also permissible to use nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene lauryl ether. In addition, it is preferable to use a polymerization initiator during the reaction, and as the polymerization initiator, for example, potassium persulfate-sodium hydrogen sulfite, ammonium persulfate-sodium hydrogen sulfite based water-soluble initiators are preferably used, but peroxide There is no problem in using an oil-soluble initiator such as benzoyl or azobisisobutyronitrile in combination. Furthermore, although the amount of surfactant used varies somewhat depending on the type of surfactant used,
Preferably ~0.1 to 5.0 based on total monomers used
%. If the amount is less than 0.1%, polymerization stability and dispersion stability will be poor, and if it exceeds 5%, the properties of the baked film will deteriorate. The amount of polymerization initiator used varies depending on the type of initiator, but the amount of water-soluble initiator is 0.05
A suitable amount is about ~3.0%, and if it is less than 0.05%, there are disadvantages such as a decrease in the polymerization rate, and
If the amount exceeds 3.0%, the dispersion stability will increase, elution of coated metal ions during electrodeposition will increase, and the film properties will be adversely affected. If the minimum film-forming temperature of the water-dispersed particles of the hard component is less than 80°C, the insulation properties, especially the temperature characteristics, of the resulting cured electrodeposited film will deteriorate, and the minimum film-forming temperature of the polymer of the soft component will deteriorate. If the temperature exceeds 60°C, the film forming temperature will not be lowered, which is not preferable in any case. Hereinafter, the present invention will be explained in more detail with reference to comparative examples and examples of the present invention. Comparative example 1 Lauryl sulfate ester soda in a four-necked flask
1.0 part, ion exchange water 600 parts, acrylonitrile 96
1 part, 48 parts of styrene, 36 parts of ethyl acrylate, 10 parts of glycidyl methacrylate, and 10 parts of methacrylic acid, and after passing nitrogen through it for about 30 minutes while stirring, the temperature was raised, and when it reached 65°C, 0.4 parts of potassium persulfate,
A solution prepared by dissolving 0.13 parts of sodium bisulfite in 100 parts of ion-exchanged water was added and reacted at 65 to 70°C for 4 hours to obtain an aqueous dispersion with a nonvolatile content of about 20%. The minimum film forming temperature of the resulting aqueous dispersion was 70°C. Put the aqueous dispersion into a 200c.c. graduated cylinder,
An electrodeposited film was obtained by applying a DC voltage of 5 V using a bare copper wire as a counter electrode. The resulting electrodeposited film was heated at 80℃ for 30 minutes, then at 180℃.
The electric wire heated for 2 hours at 100°C had a lot of foaming and cracks. In addition, after immersing the electrodeposited film in warm water at 85°C for a few seconds,
The wire heated at 180°C for 30 minutes and then 2 hours at 180°C was able to form a continuous film. Further, the electrodeposited film was immersed in dimethylformamide (DMF) for several seconds, and then heated at 80°C for 30 minutes.
The electric wire heated at 180°C for 2 hours had a good appearance and was uniform. Comparative Example 2 In a four-necked flask, 1.0 part of sodium laurylbenzenesulfonate, 600 parts of ion-exchanged water, 60 parts of acrylonitrile, 30 parts of styrene, and 90 parts of ethyl acrylate.
parts, glycidyl methacrylate 10 parts, methacrylic acid
Prepare 10 parts and reduce the non-volatile content in the same manner as in Comparative Example 1.
A 20.5% aqueous dispersion was obtained. The minimum film forming temperature of the resulting aqueous dispersion was 55°C. Electrodeposition was carried out in the same manner as in Comparative Example 1 using the aqueous dispersion, and when the electrodeposited film was heated at 80°C for 30 minutes and then at 180°C for 2 hours, a continuous film was obtained. Further, the electrodeposited film was immersed in hot water at 85°C for several seconds, heated at 180°C for 30 minutes, and then heated at 180°C for 2 hours to obtain an electric wire with a continuous film. Further, the electric wire obtained by immersing the electrodeposited film in dimethylformamide for several seconds and then heating it at 80°C for 30 minutes and then at 180°C for 2 hours had a good appearance and was uniform. Example 1 Lauryl sulfate ester soda in a four-necked flask
1.0 parts, 600 parts of ion exchange water, 96 parts of acrylonitrile
parts, 48 parts of styrene, 16 parts of glycidyl methacrylate
1 part and 16 parts of methacrylic acid, and while stirring, add approx.
After bubbling with nitrogen for 30 minutes, the temperature was raised to 65°C, and then 0.4 parts of potassium persulfate and sodium hydrogen sulfite were added.
A solution of 0.13 parts dissolved in 100 parts of ion-exchanged water was added and reacted for 15 minutes, followed by ethyl acrylate 36
A mixed solution of 4 parts of glycidyl methacrylate and 4 parts of methacrylic acid was added dropwise from the dropping funnel over a period of 30 minutes, and after the addition was completed, the mixture was reacted at 65 to 70°C for 3 hours to obtain an aqueous dispersion with a nonvolatile content of about 20%. Note that the first organic compound contains about 81.8% acrylonitrile and styrene, and about 18.2% glycidyl methacrylate and methacrylic acid, and assuming that the total weight is 100, the second organic compound contains about 81.8% ethyl acrylate, and about 18.2% glycidyl methacrylate and methacrylic acid. Contains about 18.2% methacrylate and methacrylic acid, for a total of 25%. The minimum film-forming temperature of the resulting aqueous dispersion was about 35°C. The dispersion liquid was subjected to three types of treatments in the same manner as in Comparative Example 1 to obtain electric wires. Example 2 Oleyl sulfate ester soda in a four-necked flask
1.0 parts, polyoxyethylene alkyl ether 1.0
parts, ion exchange water 600 parts, acrylonitrile 96 parts
parts, 30 parts of methyl methacrylate, 18 parts of vinyl acetate
1 part, 5 parts of glycidyl methacrylate, and 5 parts of methacrylic acid. After passing nitrogen through the mixture for about 30 minutes while stirring, the temperature was raised to 65°C. When the temperature reached 65°C, 0.3 part of ammonium persulfate and 0.1 part of sodium hydrogen sulfite were added.
A solution dissolved in 100 parts of ion-exchanged water was added and reacted for 20 minutes, and then a solution of 0.5 parts of benzoyl peroxide dissolved in 20 parts of ethyl acrylate, 5 parts of glycidyl methacrylate, and 5 parts of methacrylic acid was added through a dropping funnel for 45 minutes. Drop once, 70~75 after dripping is finished.
The reaction was carried out at ℃ for 2.5 hours to obtain an aqueous dispersion with a non-volatile content of about 20.4%. Note that the first organic compound is acrylonitrile,
Methyl methacrylate and vinyl acetate approximately 93.5
%, contains about 6.5% glycidyl methacrylate and methacrylic acid, and assuming this total weight is 100, the second organic compound contains about ethyl acrylate.
Contains approximately 33.3% of glycidyl methacrylate and methacrylic acid, with a total weight of approximately
It is 19.5. The minimum film formation temperature of the resulting aqueous dispersion is approximately 45℃.
It was hot. The aqueous dispersion was treated in the same manner as in Comparative Example 1,
I got the electric wire. Example 3 A four-necked flask was charged with 2.0 parts of sodium laurylbenzenesulfonate, 600 parts of ion-exchanged water, 108 parts of acrylonitrile, 32 parts of styrene, 30 parts of methyl methacrylate, 5 parts of N-methylolacrylamide, and 5 parts of methacrylic acid, and stirred. After bubbling with nitrogen for about 30 minutes, the temperature was raised to 65°C, and then a solution of 0.2 parts of potassium persulfate and 0.07 parts of sodium bisulfite dissolved in 100 parts of ion-exchanged water was added.
After reacting for 1 minute, 0.75 parts of azobisisobutyronitrile was added to 18 parts of n-propyl methacrylate.
1 part, N-methylolacrylamide 5 parts, and methacrylic acid 5 parts was added dropwise from the dropping funnel over 60 minutes, and after the addition was completed, the reaction was carried out at 70°C for 3 hours to obtain an aqueous dispersion with a non-volatile content of about 19.9%. . Note that the first organic compound contains about 94.4% acrylonitrile, styrene, and methyl methacrylate, and about 5.6% N-methylolacrylamide and methacrylic acid, and assuming that the total weight is 100, the second organic compound is n-propyl methacrylate. It contains about 64.3% of N-methylolacrylamide and about 35.7% of methacrylic acid, for a total weight of about 15.6%. The minimum film formation temperature of the resulting aqueous dispersion is approximately 52℃
It was hot. The aqueous dispersion was treated in the same manner as in Comparative Example 1,
I got the electric wire. Example 4 Lauryl sulfate ester soda in a four-necked flask
30 parts, ion exchange water 600 parts, acrylonitrile 100 parts
1, 50 parts of α-methylstyrene, 5 parts of glycidyl methacrylate, and 5 parts of methacrylic acid. After passing nitrogen through the mixture for about 30 minutes while stirring, the temperature was raised to 65°C.
After that, a solution of 0.5 parts of ammonium persulfate and 0.17 parts of sodium hydrogen sulfite dissolved in 100 parts of ion-exchanged water was added, and after reacting for 30 minutes, 30 parts of ethyl acrylate, 5 parts of glycidyl methacrylate, and methacrylic acid were added. 5 parts of the mixed solution was dropped from the dropping funnel for 30 minutes, and after the dropping was completed, it was heated to 70°C.
The mixture was reacted for 3 hours to obtain an aqueous dispersion with a non-volatile content of about 20%. Note that the first organic compound contains 93.8% acrylonitrile and α-methylstyrene, and about 6.2% glycidine methacrylate and methacrylic acid, and assuming this total weight is 100, the second organic compound contains 75% ethyl acrylate, Contains 25% glycidyl methacrylate and methacrylic acid,
This total weight is 25. The minimum film forming temperature of the resulting aqueous dispersion was 42°C. A wire was obtained by processing in the same manner as in Comparative Example 1 using the aqueous dispersion. The wire characteristics shown in Table 1 for the wires obtained in Comparative Examples 1 to 2 and Examples 1 to 4 above were determined according to JIS 3202.
Measured according to. The results are summarized in Table 1.

[Table] Furthermore, Table 2 summarizes the volume resistivity values measured for the DMF-treated samples in Comparative Examples and the non-treated samples in Examples.

【table】

[Table] As is clear from the results in Table 1, the electrodeposition coating using the electrodeposition paint of the present invention has a good appearance even when untreated, and should satisfy the electric wire characteristics. Furthermore, since the glass transition temperature (Tg) is extremely high compared to that of the comparative example, it can be seen that the properties at high temperatures are also excellent. Further, as is clear from the results in Table 2, the examples according to the present invention have extremely high volume resistivity even at high temperatures, and the effects of the present invention are evident. Note that the above embodiments are for illustrative purposes only, and are not limited thereto. Therefore, it goes without saying that the application is not particularly limited to electric wires, for example. As explained above, according to the present invention, an organic solvent is not required when forming a continuous film, and an electrodeposited film with excellent high-temperature insulation properties can be obtained.

Claims (1)

[Claims] 1 80 to 95% by weight of at least two species containing acrylonitrile selected from the group consisting of acrylonitrile, styrene, α-methylstyrene, methyl methacrylate, and vinyl acetate; and 80 to 95% by weight of at least two types selected from the group consisting of glycidyl methacrylate, methacrylic acid, and N-methylolacrylamide. 5-20% by weight of at least two types containing methacrylic acid
A polymer obtained by polymerizing 100 parts by weight of a first organic compound that provides a minimum film-forming temperature of 80°C or higher for water-dispersed particles; at least one selected from the group consisting of ethyl acrylate and n-propyl methacrylate, which can give
85% by weight and 15 to 25 parts by weight of a second organic compound consisting of 15 to 40% by weight of at least two species including methacrylic acid selected from the group consisting of glycidyl methacrylate, methacrylic acid and N-methylol acrylamide. A water-dispersed electrodeposition paint containing a copolymer obtained by