JPS6043306B2 - Anti-corrosion separator film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel anti-corrosion separator film.

More specifically, the present invention relates to an anticorrosive separator tape that can prevent discoloration of copper conductors in insulated wires. In the following description, the present invention will be explained using such a separator tape as a representative. BACKGROUND ART Conventionally, insulated wires in which a synthetic resin separator tape is interposed between a copper conductor and an insulating layer covering the conductor have been widely used. In this case, the separator tape prevents the insulation layer-forming substance from falling into the gaps between the stranded copper conductors during the manufacturing process of coating the insulation layer on the stranded copper conductors, and also prevents the insulation layer from falling into the gaps between the stranded copper conductors. It is provided to make it easier to remove. However, when using cross-linked polyethylene as the insulating layer, the manufacturing process usually involves adding a cross-linking agent to the polyethylene resin and coating it on the copper conductor via a separator tape. The crosslinking reaction is carried out in a steam atmosphere of 15 atm at 200°C, but in such a high-temperature, high-pressure steam atmosphere, water that has passed through the insulating layer and separator tape or decomposition products generated under such conditions can cause a crosslinking reaction. As a result, the surface of the copper conductor often becomes yellow or dark brown in spots, and in some cases, the surface of the copper conductor may even be discolored over a considerable area.

This phenomenon is caused by the influence of atmospheric humidity even during storage of electric wire products or use as crosslinkers.

Such discoloration on the surface of a copper conductor does not have a negative effect on its electrical properties, but when the insulating layer and separator tape are peeled off from the copper conductor during use, the discoloration is exposed and significantly reduces its commercial value. lower.

In addition, when the discoloration is significant, it often has the disadvantage that solderability deteriorates. For this reason, rust prevention treatments such as applying rust preventive agents such as benzotriazole directly onto copper conductors or separator tapes have traditionally been carried out, but these methods are also not satisfactory in preventing discoloration of copper conductors. For example, if an insulated wire that has been treated with rust prevention directly on a copper conductor is left outdoors, the copper conductor will turn dark brown in about 300 days.

However, as a result of extensive research in order to eliminate the above-mentioned drawbacks, the present inventors have found that when providing a corrosion protection layer of polyvinyl alcohol containing a water-soluble rust inhibitor on one or both sides of a synthetic resin separator film, The present invention was completed based on the new discovery that it is possible to provide an anticorrosive separator film that eliminates the disadvantages of copper conductors and prevents discoloration of copper surfaces such as copper conductors.

That is, the separator tape of the present invention is characterized in that a corrosion protection layer of polyvinyl alcohol containing a water-soluble rust preventive agent is provided on the surface of the separator tape that comes into contact with a copper surface such as a copper conductor.

However, in the present invention, by using a water-soluble rust preventive agent as the rust preventive agent and using water-soluble polyvinyl alcohol as the resin containing the rust preventive agent, the copper conductor is free from moisture that causes copper discoloration. The rust preventive agent is diffused onto the surface of the copper conductor along with polyvinyl alcohol by utilizing the penetration of moisture into the surface of the copper conductor, forming an anti-corrosion film on the surface of the copper conductor, thereby preventing discoloration of the copper conductor caused by the intrusion of moisture. It is something that forces you to do something. Next, the separator tape according to the present invention will be explained using the drawings.

FIG. 1 is a schematic sectional view showing one embodiment of the separator tape of the present invention, and FIG. 2 is a schematic sectional view showing one embodiment of the insulated wire obtained using the separator tape of the present invention.

In FIG. 1, 1 is a separator tape, and an anticorrosion layer 2 is provided on the lower surface of the separator tape 1.

The anti-corrosion layer 2 is integrally bonded to the separator tape 1 by polyvinyl alcohol constituting the anti-corrosion layer 2. FIG. 2 shows an insulated wire 3 obtained using the separator tape 1 according to the present invention. In addition, the anti-corrosion layer 2 is provided on the contact surface with the copper conductor 5 as shown in FIG. The anti-corrosion layer 2 provided on the separator tape 1 is made by mixing water-soluble polyvinyl alcohol and an alcohol solution in which a water-soluble rust preventive agent is dissolved, and applying this mixture using an appropriate coating method such as a barcoder method. It is formed by coating the separator tape 1 on the separator tape 1, and then drying it in a hot air circulating open system.

At that time, the mixed solution contains about 0.2 to 2.4% of a water-soluble rust inhibitor.
(% by weight, hereinafter the same), preferably at a concentration of 0.5 to 1%, and polyvinyl alcohol at a concentration of about 3 to 15%, preferably 4 to 8%.

The thus obtained mixed solution is applied to the separator tape 1 and dried as described above, and the thickness of the anticorrosion layer 2 that is formed is adjusted to be in the range of 0.5 to 25μ, preferably 1 to 5μ. Ru. When the concentration of the water-soluble rust preventive in the mixed liquid is lower than the above range, its anticorrosion properties are poor;
Furthermore, even if the ratio is increased beyond the above range, the rust preventive effect will not be improved to a corresponding extent, and it will be economically disadvantageous, both of which are undesirable.

Furthermore, when the concentration of polyvinyl alcohol in the mixed solution is lower than the above range, the adhesive strength of the anticorrosion layer 2 formed on the surface of the separator tape 1 will be poor, and when it is higher than the above range, the rust preventive agent will be weak. A large amount of polyvinyl alcohol, which is a binder, is eluted onto the surface of the copper conductor 5, and the separator tape 1 and the copper conductor 5 adhere to each other, causing problems in connection work such as terminal connection, which are both undesirable. Furthermore, when the thickness of the anti-corrosion layer 2 is smaller than the above range, the copper conductor 5
The strength of the anticorrosion coating formed thereon and its anticorrosion properties are poor, and if it exceeds the above range, it is economically disadvantageous, and both are not preferred. Therefore, the anticorrosion layer 2 used in the present invention is a layer containing about 1.3 to 80 parts by weight of a water-soluble l rust inhibitor per 100 parts by weight of polyvinyl alcohol, and has a thickness of 0.5 to 25 μm, especially 1 to 5 μm. It is preferable that

Examples of the water-soluble rust preventive include benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, benzotriazole morpholine salt, benzotriazole diisopropylamine salt, benzotriazole isopropylamine salt, methylbenzotriazole cyclohexyl Examples include huamine salt.

These rust inhibitors are made by adding various amines to benzotriazole, which is well known as a rust inhibitor for copper and copper alloys, to make it water-soluble. Such a water-soluble rust preventive agent easily dissolves in moisture that has entered the insulated wire 3 under the above-mentioned high-temperature, high-pressure steam atmosphere or under the influence of atmospheric humidity, and forms an anti-corrosion coating on the surface of the copper conductor 5 along with polyvinyl alcohol. form. The separator tape 1 used in the present invention includes, for example, polyester resin (for example, Mylar manufactured by DuPont),
Examples include tapes with a thickness of about 25 μm conventionally used as separator tapes, such as polyamide-imide resin, polyamide resin, polyphenylene oxide resin, polyether sulfone resin, and polysulfone resin.

The insulating layer 3 may be made of, for example, a conventionally known crosslinked or non-crosslinked polyolefin polymer.

Such polyolefin polymers include, for example, polyethylene, polypropylene, and ethylene-propylene copolymers, and when these polymers are crosslinked, dicumyl peroxide (hereinafter referred to as DCP) may be used as a crosslinking agent. used. The insulated wire 3 thus obtained is resistant to moisture entering from the atmosphere, not only when the polyolefin polymer is subjected to a crosslinking reaction in a high-temperature, high-pressure steam atmosphere, but also during product storage or use. The anticorrosive layer 2 provided on the separator tape 1 prevents the surface of the copper conductor 5 from being discolored, and therefore does not reduce its commercial value as an electric wire or its solderability.

As described above, the separator tape 1 of the present invention is placed on the copper surface of the copper conductor 5, etc., and prevents the copper surface from discoloring due to moisture, and has extremely high practical value. It is.

The above separator film of the present invention is representative of separator tapes used in insulated wires. ``As explained above, the separator film of the present invention is not limited to such a tape-like one, but can also be used to prevent discoloration of copper surfaces such as copper plates with an anticorrosive layer made of a water-soluble rust preventive agent and polyvinyl alcohol. There is no particular limitation as long as it can be used as a material, and even a film-like material is included within the scope of the claims of the present invention.

An example of using the separator film of the present invention in film form is, for example, interposing the separator film of the present invention between stacked copper plates to prevent discoloration of the surface of each copper plate.

That is, in general, when copper plates and the like are stacked and stored for a long period of time under humid conditions, there is a problem in that the surface of each stacked copper plate becomes discolored, which significantly reduces the commercial value.

For this reason, rust-proofing paper made by impregnating paper with a rust-proofing solution has traditionally been interposed between the stacked copper plates.
The water absorption capacity of the paper itself is low, and even if the paper absorbs water, the rust preventive agent impregnated in the paper is not sufficiently eluted to the copper surface, so it is difficult to prevent discoloration of the copper surface. However, it could not be said that it was satisfactory. However, when providing a corrosion protection layer of polyvinyl alcohol containing a water-soluble rust inhibitor on the surface of the separator film that contacts the copper plate surface,
As mentioned above, the water-soluble rust preventive agent is eluted onto the surface of the copper plate by the water that has entered along with the polyvinyl alcohol, forming an anticorrosive film on the surface and preventing discoloration of the surface of the copper plate caused by the intrusion of water. Therefore, the drawbacks mentioned above are eliminated. In order to facilitate understanding of this, FIG. 3 is a schematic cross-sectional view showing one embodiment of the separator film of the present invention, and FIG. 3 shows a state in which the separator film of the present invention is interposed between laminated copper plates. Please refer to FIG. 4, which is a schematic cross-sectional view.

In FIG. 4, a separator film 6 having anti-corrosion layers 2a on both sides is interposed between each of the stacked copper plates 7. Next, the separator tape according to the present invention will be explained with reference to Examples.

Example 100 g of a 2% methanol solution of benzotriazole monoethanolamine salt, which is a water-soluble rust inhibitor, and 100 g of a 10% aqueous solution of polyvinyl alcohol were mixed to create a mixed solution containing 1% of the rust inhibitor and 5% of polyvinyl alcohol. was prepared.

A polyester resin tape with a thickness of 25 μm was used as a separator tape, and the mixed solution was applied to the tape by a percoater method, and the mixture was dried at 130° C. for 2 minutes in a hot air circulation system to form an anticorrosive layer with a thickness of 1.0 μm. formed.

Then, a separator tape was formed on a copper conductor made of bare copper stranded wire (7/2.6 m..38 d) vertically into a cylindrical shape with the anti-corrosion layer facing the conductor side.

The thus obtained electric wire was coated with 1.5% DCP as a crosslinking agent.
Thickness 2 with polyethylene resin contained in it? After coating, a crosslinking reaction was carried out at a temperature of about 200° C. in a steam atmosphere of 15 atm to obtain an insulated wire.

Despite the aforementioned crosslinking reaction in a steam atmosphere, no discoloration was observed on the surface of the copper conductor. Next, the results of a test to investigate the corrosion resistance of the separator tape according to the present invention thus obtained will be shown.

The above separator tape (wire not covered with an insulating layer) was used as a sample for the test, and the separator tape (wire not covered with an insulating layer) was formed by longitudinally splicing the bare copper stranded wire obtained as described above. A separator tape made only of the above-mentioned polyester resin tape and two types of commercially available separator tapes [corrosion-resistant separator tape with a thickness of 25 μm made of polyester tape coated with benzotriazole (hereinafter referred to as commercially available separator tape 1) and cotton tape coated with benzotriazole. The corrosion resistance was compared with that obtained by using a 30μ thick impregnated corrosion-resistant separator tape (hereinafter referred to as commercially available separator tape 1).

The test was performed on these samples at a temperature of 65°C and a relative humidity of 95% R.
The copper conductor was heated for one full hour, then left at room temperature for one full hour, and this was counted as one cycle. After repeating a total of 10 cycles, the degree of discoloration on the surface of the copper conductor was determined in accordance with JIS K2513 (1978).

The test results are shown in Table 1. JISK25l3(19
The criteria for determining discoloration based on 78) are as follows.

Discoloration number 1: Slight discoloration 1a: Light orange (as before the test
Same color) 1b: Dark orange Discoloration number 2: Moderate discoloration (pink color or gold) Discoloration number 3: Dark discoloration (reddish-brown pattern or
is a multicolored pattern with red and green) Discoloration number 4: Corrosion (bluish-purple with green or black) Also, the degree of discoloration of the copper conductor when the insulated wire obtained in this example was left outdoors or indoors for a long time. The results of the investigation are shown below.

The samples used in the test are as follows.

(1) Insulated wire obtained in this example (2) Insulated wire in which the copper conductor was anti-rust treated with a 1% methanol solution of benzotriazole (separator tape has no anti-corrosion layer) (3) 1% ethylene of benzotriazole Copper conductors are treated with a glycol solution to prevent rust and insulated wires (separator tape does not have an anti-corrosion layer).

(4) Bare copper stranded wire (described above) alone (5) Insulated wire (
6) The degree of discoloration of an insulated wire obtained in the same manner as in Example except that commercially available Separator Tape 2 was used as the separator tape was determined based on the criteria in JIS K2513 (1978).

(4) The degree of discoloration of copper conductors when left outdoors
Temporal change test conditions The samples were left outdoors and the degree of discoloration was observed every 100 days.

The test results are shown in Table 2.

(B) Temporal change in degree of discoloration of copper conductor when left indoors Test conditions The copper conductor was left indoors, and the degree of discoloration was observed every 100 days.

The test results are shown in Table 3.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the separator tape of the present invention, FIG. 2 is a schematic sectional view showing an embodiment of the insulated wire obtained using the separator tape of the present invention, and FIG. FIG. 4 is a schematic cross-sectional view showing one embodiment of a separator film, and FIG. 4 is a schematic cross-sectional view showing a state in which the separator film of the present invention is interposed between laminated copper plates. (Drawing code) 1...Separator tape,
2, 2a... Corrosion protection layer, 3... Insulated wire,
4... Insulating layer, 5... Copper conductor, 6...
...Separator film, 7...Copper plate.

Claims (1)

[Scope of Claims] 1. An anti-corrosion separator film, characterized in that an anti-corrosion layer of polyvinyl alcohol containing a water-soluble anti-rust agent is provided on one or both sides of a synthetic resin separator film. 2. The anticorrosion layer according to claim 1, wherein the anticorrosion layer is a layer containing about 1.3 to 80 parts by weight of a water-soluble rust inhibitor based on 100 parts by weight of polyvinyl alcohol and having a thickness of 0.5 to 25 μm. film.