JPH0224869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an electrodeposition paint comprising mica powder dispersed in water and a water-dispersible varnish. More specifically, we manufacture electrodeposition paints made of mica powder, an inorganic insulating material used to form an electrodeposited insulating layer on electrical conductors by electrophoresis, water-dispersible varnish, an organic insulating material, and water. Before mixing them, the water-dispersed varnish is subjected to ultrafiltration or reverse osmosis treatment to adjust the liquid specific resistance of the water-dispersed varnish, which is suitable as a binder for insulating mica. The present invention relates to a method for producing an electrodeposition paint, which is characterized by removing miscellaneous ions. In the method of electrodepositing mica powder alone onto an electrical conductor, the strength of the electrodeposited insulating layer formed is not sufficient, and when the electrical conductor is removed from the electrodeposition paint, the electrodeposited insulating layer is formed. There was a defect that the mica ran down. For this reason, an electrodeposition paint and its manufacturing method are known in which the mechanical strength and electrical properties of an electrically insulating layer are improved by using a water-dispersed varnish as a binder for mica powder (Japanese Patent Application Laid-Open No. 51-197-1).
89178, JP-A-51-114602, see). The factors governing the mechanical strength and electrical properties of an electrodeposited insulating layer manufactured using an electrodeposition paint consisting of mica powder and water-dispersed varnish are mainly the mica content of the electrodeposited insulating layer and the size of the mica powder. and the water content of the electrically insulating layer, both of which can be controlled at the stage of preparing the electrodeposition paint. However, when co-electrodepositing mica powder and water-dispersed varnish, the surface charge density of the water-dispersed varnish is generally larger than that of the mica powder, so the potential is much higher for the water-dispersed varnish. Due to the large size of the mica powder and the excessive weight of the mica powder, the electrophoresis speed is extremely different, resulting in a phenomenon in which the compositions of the electrodeposited paint and the electrodeposited insulating layer in the electrodeposition tank differ greatly. . As a method to solve this drawback, the present inventors
If the electrophoresis speeds of mica powder and water-dispersible varnish are the same, the composition of the electrodeposition paint in the electrodeposition bath and the composition of the electrical insulation layer will be constant. We tried various methods to equalize the electrophoresis speed by making the specific resistance of the liquid and the water-dispersed varnish similar. As an example, when using a method of adjusting the liquid resistivity of a water-dispersed varnish using a dialysis tube or electrodialysis method, it is possible to remove miscellaneous ions in the water-dispersed varnish, so negative ions in the miscellaneous ions can be removed. Water does not migrate to the positive electrode, that is, the electrical conductor, and as a result, the water content of the electrical insulating layer decreases, and the mica powder is arranged densely and parallel to the surface of the electrical conductor, forming a mechanical structure in the electrical insulating layer. It was found that the strength of the target could be improved. However, in the dialysis tube method or electrodialysis method, it takes a long time to adjust the liquid specific resistance of the water-dispersed varnish and remove miscellaneous ions, and when a dialysis tube is used, a so-called batch method is used to process a large amount of water-dispersed varnish. The disadvantages are that it requires a lot of manpower to do this, and that the dialysis tube itself is difficult to use continuously due to its strength. The present inventors have discovered a method using ultrafiltration or reverse osmosis as a method capable of adjusting the liquid resistivity of a large amount of water-dispersed varnish and removing miscellaneous ions in a short time and continuously. In other words, the present invention aims to adjust the liquid resistivity of the water-dispersed varnish and to adjust the liquid specific resistance of the water-dispersed varnish before dispersing the mica powder and the water-dispersed varnish in order to equalize the electrophoresis speed of the mica powder and the water-dispersed varnish. The present invention relates to a method for producing an electrodeposition paint, characterized in that the removal of is carried out by ultrafiltration or reverse osmosis treatment. The permeable membrane used in the ultrafiltration or reverse osmosis treatment in the present invention may be any known one. Further, the concentration of the water-dispersed varnish is suitably 5 to 30% by weight, and the liquid resistivity is suitably 1000 to 5000 Ωcm. Next, the method of the present invention will be explained based on the drawings.
FIG. 1 is a schematic diagram of a processing apparatus for adjusting the liquid resistivity and removing miscellaneous ions of a water-dispersed varnish used in the present invention. 1 is a tank for storing the water-dispersible varnish, 2 is the water-dispersible varnish, 3 is piping for the water-dispersible varnish, 4a is a pump for flowing the water-dispersible varnish, and 4b is the recycled permeate that is returned to tank 1. 5a is a valve for adjusting the flow rate and pressure of the water-dispersed varnish flowing into the permeable membrane; 5b is a valve for adjusting the flow rate and pressure of the water-dispersed varnish flowing out from the permeable membrane; 6a is a valve for adjusting the flow rate and pressure of the water-dispersed varnish flowing out from the permeable membrane; A pressure gauge, 6b is a pressure gauge at the outlet of the permeable membrane, 7 is a permeable membrane, 8 is an ion exchange resin for regenerating permeated water, 9 is a flow of permeated liquid,
10 is a tank for storing the regenerated permeate, and 11 is the regenerated permeate. A water-dispersed varnish and ion-exchanged water are put in a tank 1 of this treatment device, and the water-dispersed varnish diluted with ion-exchanged water is sent to a permeable membrane 7 by a pump 4a, and the permeated liquid is separated into a concentrated liquid and a permeated liquid by the permeable membrane 7. separated. The concentrated water-dispersible varnish is returned to tank 1, while the permeate is regenerated with ion exchange resin 8 and enters tank 10. Recycled permeate water 11 from tank 10
is returned to tank 1 by pump 4b. By repeating this several times, the liquid specific resistance of the water-dispersed varnish can be adjusted and miscellaneous ions can be removed. Next, the water-dispersed varnish used in the present invention is prepared by adding an acid-added epoxy resin with an acid value of 30 to 60 from, for example, 100 parts of Epicote 1001 (an epoxy resin manufactured by Ciel Chemical Co., Ltd.), 25 parts of tetrahydrophthalic anhydride, and 6 parts of ethylene glycol. It can be obtained by dispersing this resin in warm water containing ammonia and then blowing nitrogen gas into it. Next, the method of the present invention will be explained with reference to Examples and Comparative Examples. In the Examples and Comparative Examples below, a liquid having a pH of 7.0, a nonvolatile content of 8.0%, and a liquid specific resistance of 250 Ωcm was used. Example 1 Water-dispersed varnish 30 and ion-exchanged water 30 of 5 MΩcm or more were placed in tank 1 and passed through the permeable membrane at a flow rate of approximately 12/min, and the concentrated liquid was returned to tank 1 at a flow rate of approximately 2/10 min. After repeating the process of returning the permeated liquid to tank 1 at a rate of about 10 per hour about 6 times, the process of returning the permeated liquid to tank 1 was stopped, and the excess ion-exchanged water was allowed to permeate. , PH7.0 after 9 hours, non-volatile content 7.90%, liquid specific resistance 2000Ωcm
A water-dispersible varnish was obtained. To 20 parts of the solid content of this water-dispersible varnish, 80 parts of mica powder of 35 mesh pass, which has been thoroughly washed with ion-exchanged water, is mixed, and ion-exchanged water is added and stirred well, resulting in a uniformly dispersed non-volatile content of 15%. An electrodeposition paint was prepared. A hexagonal-shaped coil previously formed in this electrodeposition paint was immersed, and a DC voltage of 100 V was applied for 20 seconds between the poles and a counter electrode with a distance of 50 cm to form an electrodeposited insulating layer on the coil. Table 1 shows the results of examining the film layers and composition of the formed insulating layer. Example 2 Solid content of water-dispersed varnish prepared in Example 1: 30
An insulating layer was formed on the coil in the same manner as in Example 1, except that 70 parts of mica powder and 70 parts of mica powder were used. Table 1 shows the thickness and composition of the obtained insulating layer. Example 3 Solid content of water-dispersed varnish prepared in Example 1: 10
An insulating layer was formed in the same manner as in Example 1, except that 90 parts of mica powder and 90 parts of mica powder were used. Table 1 shows the thickness and composition of the obtained insulating layer. Comparative Example 1 The water-dispersed varnish 30 having a pH of 7.0, a nonvolatile content of 8.0%, and a liquid specific resistance of 250 Ωcm was placed in several dialysis tubes (VISKING tubes manufactured by Shiraimatsu Kikai Co., Ltd.).
Add 10% of the water-dispersible varnish in a dialysis tube to 3 containers containing 30% of ion-exchanged water of 5MΩcm or more.
PH6.8, non-volatile content 7.5 after 96 hours
% and a water-dispersed varnish with a liquid specific resistance of 2000Ωcm. After mixing 80 parts of mica powder of 35 mesh pass thoroughly washed with ion-exchanged water to 20 parts of the solid content of this water-dispersible varnish, an insulating layer was formed on the coil in the same manner as in Example 1. Table 1 shows the thickness and composition of the obtained insulating layer. Comparative Example 2 Solid content of water-dispersed varnish prepared in Comparative Example 1: 10
After mixing 90 parts of mica powder of 35 mesh pass thoroughly washed with ion-exchanged water, Example 1
An insulating layer was formed on the coil using the same method. Table 1 shows the thickness and composition of the obtained insulating layer. 【table】

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a water-dispersed varnish processing apparatus used in the present invention. Reference numbers in the drawings: 1: tank, 2: water-dispersed varnish, 3: flow of water-dispersed varnish, 4a, 4b: pump, 5a, 5b: valve, 6a, 6b: pressure gauge,
7: Permeable membrane, 8: Ion exchange resin, 9: Permeate flow, 10: Tank, 11: Regenerated permeate.

Claims (1)

[Claims] 1. Ultrafiltration or reverse osmosis treatment is applied to the water-dispersed varnish to increase the liquid specific resistance of the water-dispersed varnish and remove miscellaneous ions in the water-dispersed varnish, and then the water-dispersed varnish is treated with mica powder. A method for producing an electrodeposition paint, which comprises mixing the following: and water. 2. The method for producing an electrodeposition paint according to claim 1, wherein the water-dispersible varnish is an epoxy ester-based water-dispersible varnish. 3. A circulation circuit is formed between the stock solution tank of the water-dispersed varnish and an ultrafiltration device or a reverse osmosis treatment device, and a part of the water-dispersed varnish is subjected to ultrafiltration or reverse osmosis treatment to form a concentrated liquid and a permeated liquid. The concentrated liquid is returned to the stock solution tank, and the permeate is regenerated using an ion exchange resin and returned to the stock solution tank.
Claim 1, characterized in that this operation is repeated until the water-dispersed varnish reaches a desired liquid resistivity and miscellaneous ions in the water-dispersed varnish are removed.
Method for manufacturing the electrodeposition paint described in Section 1.