JPS5849966B2 - electric power plant - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrode coating material having a novel composition.

As a conventional electrode paint, a paint containing a thermosetting resin binder and silver powder is known.

When this electrode paint is used and a voltage is applied to the electrode in a humid atmosphere, a so-called silver migration phenomenon occurs in which silver powder migrates from the anode to the cathode, which not only changes the insulation resistance between the electrodes but also , it has the disadvantage of short-circuiting at the end.

In addition, there is also a known paint in which silver-coated copper powder is mixed with a thermosetting resin binder, but when this paint is used, the resulting electrode surface has extremely high wear resistance. This method could not be put to practical use because it was poor and caused problems such as changes in the specific resistance of the electrode due to wear, and the electrode paint itself had an extremely short pot life.

The present inventors have completed the present invention as a result of various studies to solve these drawbacks.

The present invention (circle (4) silver-coated copper powder, which is copper powder coated with silver, (silver-coated bismuth oxide powder, which is silver-coated I3 bismuth oxide powder, and silver-coated carbon powder, which is silver-coated O carbon powder). and ■silver powder; (6) thermosetting resin; and (6)
This is an electrode paint consisting of a solvent.

When silver-coated copper powder and silver powder are used, the wear resistance is poor and cannot be put to practical use.

Further, even when silver-coated copper powder, silver-coated bismuth oxide powder, and silver powder are used, the wear resistance is too low to be put to practical use.

Even when silver-coated copper powder, silver-coated carbon powder, and silver powder are used, the wear resistance is still poor and it cannot be put to practical use.

However, we found unexpected results in that wear resistance was high and silver migration did not occur only when four materials were used: silver-coated copper powder, silver-coated bismuth oxide powder, silver-coated carbon powder, and silver powder. The inventors discovered this.

In terms of gelation, when silver-coated copper powder is used, the paint tends to gel easily, but silver-coated copper powder,
Paints containing silver-coated bismuth oxide powder, silver-coated carbon powder, and silver powder are excellent in preventing gelation, although the theoretical reason is not necessarily clear.

The preferred proportions of the silver-coated metal powder or the silver-coated metal oxide powder in the present invention are, when the total of these silver-coated powders is 100 parts by weight, silver-coated copper powder: 5 to 30 parts by weight, silver-coated bismuth oxide powder: 3 to 30 parts by weight. 20 parts by weight silver-coated carbon powder
2-15 parts by weight Silver powder 30-7
It is 0 parts by weight.

Silver-coated copper powder used in the present invention, silver-coated bis oxide MIBK
1 parts by weight ano 7
1 parts by weight Comparative Example 2 Using the silver-coated powder obtained in Example 1, an electrode paint having the composition shown below was manufactured.

Silver-coated copper powder 10 parts by weight Silver-coated bismuth oxide powder 20 parts by weight Silver powder
70 parts by weight phenolic resin 1
5 parts by weight Butyral resin 0.4 parts by weight TPO25 parts by weight BC13.5 parts by weight Acetic acid 1.2 parts by weight MIBK
0.2 parts by weight
0.2 parts by weight Examples 2 and 3 and Comparative Example 1
An electrode pattern shown in Figure 1 was formed on a Bakelite substrate using each of the electrode paints manufactured in , 2, and silver migration and abrasion resistance tests were conducted on each electrode material using these as test samples. Ta.

Each electrode paint was applied onto a Bakelite substrate by screen printing to form the pattern shown in Figure 1, and the temperature was gradually raised from 25 to 180°C and held at a maximum temperature of 80°C for 5 minutes. , cool slowly to room temperature again.

The formed electrode spacing is 1.5 pitch for electrodes 1 and 2, and 2.0 pitch for electrodes 3 and 4.

Test 1 (Silver migration test) A voltage of 250 V was applied between one electrode terminal to the test sample prepared above in a constant temperature and humidity chamber at a temperature of 40°C and a humidity of 95 to 97%, and the electrode spacing was 1. The degree of progress of silver migration Q was investigated for 150 hours between .5 ran and 2.0 ran.

The results are shown in FIG. 22 and FIG. 3, which show that the smaller the insulation resistance, the more silver is eluted from the anode, passes over the Bakelite substrate, and migrates toward the cathode.

Note that the samples used were those obtained in Example 2 and Comparative Example 1.

As is clear from FIGS. 2 and 3, when the coating material of the present invention is used, the insulation resistance does not change for about 100 hours, and although it decreases slightly after that, it hardly changes after 250 hours.

In this way, the change in insulation resistance over time is very small and shows an extremely stable value.

However, when the paint of Comparative Example 1 is used, the insulation resistance begins to decrease as soon as the voltage load is started, and continues to decrease as time passes.

Then, it does not show a stable value and eventually short-circuits.

When the electrode paint of the present invention is used in this way,
The insulation resistance under high humidity and voltage load conditions is extremely good, indicating that silver migration does not occur.

Test 2 (Abrasion resistance test) Using a sliding abrasion resistance measuring device that applies a sliding pressure of 50 to 81 to one point on the electrode of the test sample, the electrode surface was measured at a pressure of 30.0.
The electrode was slid 00 times, and the wear resistance of the electrode and the rate of change in the specific resistance value of the electrode were observed.

The results are shown in Table 1.

In the table, "good" means that the electrode has little wear after 30,000 times of sliding, and the base of the substrate is not exposed.
This indicates that the electrode surface is considerably worn, but the base of the substrate is not exposed, and "defective" indicates that the base of the substrate is exposed.

As described above, when the paint of the present invention is used, it exhibits an excellent effect of exhibiting extremely excellent wear resistance and having very little change in the specific resistance value of the electrode.

On the other hand, when the paint of the comparative example is used, the abrasion resistance is very poor and the specific resistance value of the electrode is very large.

This tendency is particularly remarkable in Comparative Example 2.

Comparative Example 1 has somewhat poor abrasion resistance, but when a change in specific resistance value occurs to this extent, there are many practical problems and it cannot be used.

In the case of Comparative Example 1, the silver migration was very large as seen in Test 1, and from this point of view, it is not practical at all.

As described above, the present invention is a novel and useful invention that solves the problems of silver microcrash and abrasion.

[Brief explanation of the drawing]

Figure 1 shows the electrode pattern created for the test. In the figure, 1 to 4 are electrodes, and 5 is a Bakelite substrate. Figures 2 and 3 show the results of the silver migration test.

Claims (1)

[Claims] 1(A) Silver-coated copper powder (copper powder coated with silver) and (uniform
Silver-coated bismuth oxide powder, which is bismuth oxide powder coated with silver; (C) silver-coated carbon powder, which is carbon powder coated with silver; (D silver powder; (Q thermosetting resin); and (6) solvent. Electrode paint consisting of.