JPH0445588B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a corrosion-preventing coating agent applied to a metal having a film made of a vinyl chloride composition, such as a conductor of a vinyl chloride insulated wire that is strung outdoors. [Prior art and its issues] Residual stress exists in the conductor of this type of insulated wire during the wire drawing and stranding processes, and rainwater may enter into the insulated wire (between the conductor and its covering insulation). Then,
The residual stress causes so-called stress corrosion in which corrosion of the conductor by corrosive substances (sulfur oxides, _SOx, etc.) in rainwater is promoted. This stress corrosion progresses intensively to the cutout portion of the conductor, leading to wire breakage. This phenomenon is widely known as stress corrosion disconnection. Conventionally, the following measures have been taken to prevent this stress corrosion disconnection. The twisted conductor is compressed by rolling it, converting residual stress due to tension and residual stress due to bending that occurs during twisting into compressive stress, making stress corrosion less likely to occur. A watertight compound is filled between the conductor and the insulator to prevent water from entering between them. Benzotriazole (BTA) or the reaction product of BTA and amine is applied as a sulfur oxide corrosion inhibitor onto the conductor. A liquid mixture of BTA and an epoxy, phthalic acid, or phosphoric acid plasticizer is applied onto the conductor. However, the above measures are not effective because they do not prevent corrosion itself. The means are
Filling the watertight compound is extremely troublesome and has poor productivity. The method is effective because it directly prevents corrosion of the conductor, but its prevention effect is inferior to that of the method. For this reason, this method is the most effective, but if the insulator covering the conductor is made of vinyl chloride (PVC) composition, the plasticizer is transferred (eaten) to the PVC composition and becomes sulfur oxide. Resistance is impaired and conductors corrode due to water intrusion. This mechanism is due to the fact that plasticizers such as dioctylphthalate (DOP) and salt para (chlorinated paraffin) are mixed into PVC compositions from the beginning, but with typical mixing amounts, plasticizers do not reach the saturated state. Moreover, since PVC has good compatibility with plasticizers, when it comes into contact with plasticizers, it rapidly absorbs them. For this reason, the plasticizer applied to the conductor acts as an insulator.
It is thought that it is eaten by the PVC composition. In view of the above, an object of the present invention is to effectively prevent sulfur oxide corrosion of metals due to water infiltration into the coatings of metals having PVC composition coatings, such as insulated wires whose insulators are PVC compositions. do. [Means for Solving the Problems of the Invention] In order to solve the above-mentioned problems, the present invention uses a reaction product of triazoles or imidazoles known as sulfur oxide-resistant compounds and an epoxy plasticizer. It was made into a corrosion-preventing paint. Examples of the triazoles include 1,2,3-benzotriazole, 4 or 5 methyl 1H-benzotriazole, 4 or 5 carboxy-benzotriazole, hydroxybenzotriazole and the like. Examples of the imidazoles include benzimidazole, 2methylimidazole, 2ethylimidazole, 2undemylimidazole, 2phenylimidazole, benzimidazole thiol, and the like. The above-mentioned epoxy plasticizers include epoxidized soybean oil, epoxidized linseed oil, octyl epoxy stearate, epoxy butyl stearate, di-2-ethylhexyl epoxyhexahydrophthanate, diisodecyl epoxyhexahydrophthanate, epoxy Fatty acid ester, epoxidized fatty acid monoester, epoxidized fat, epoxidized oil,
Epoxidized fatty acid ester, epoxy triglyceride, epoxidized oleate octyl ester, epoxidized oleate decyl ester, epoxy monoester, octyl epoxy tolate, epoxy monoester, alkyl epoxy stearate, n-alkyl epoxy stearate, cycloalkyl epoxy Examples include stearate, epoxy diisooctyltetrahydrophthanol, and the like. [Function] The anti-corrosion coating composition according to the present invention having the structure described above is non-migratory (the plasticizer is not eaten away) because it undergoes reaction polymerization. for example,
Benzotriazole (BTA) and epoxidized soybean oil (for example, Dainippon Ink & Chemicals: Eposizer W-100EL) are as follows. Further, for example, benzimidazole and epoxidized soybean oil (W-100EL) are as follows. [Example] First, as shown in Table 1, W100EL and BTA were mixed in a solvent-free solution of 130±
Reaction polymerization was carried out under conditions of 10°C to obtain a reaction product consisting of unreacted BTA, reacted BTA, and reacted W100EL in the weight ratio shown in the lower column of the same table, which was further dissolved in a solvent to form a stock solution of corrosion-inhibiting paint. did.

[Confirmation of effect]

Samples of 100 mm length were taken from each of the insulated wires P obtained as described above (20 times diluted solution a of Examples 1, 2, and 3 shown in Table 1 was drip applied onto the conductor 2). The insulator 3 of each sample was stripped off, and each conductor 2 thereof was immersed in a 100 ppm sodium sulfide aqueous solution (20° C.) for 30 seconds. When each conductor 2 was visually observed for discoloration, no abnormality was found in any of them. In addition, the sample collected in the same manner as above was 80±1
After leaving it in a constant temperature bath at ℃ for 30 days, take it out, peel off the insulator 3, and use the conductor 2 in the same manner as above.
After being immersed in a 100 ppm sodium sulfide aqueous solution (20°C) for 30 seconds, conductor 2 was observed for discoloration, and no abnormalities were observed. By the way, like the above method, against BTA
The material coated with W100EL mixed with isopropyl alcohol was heated for 30 days in a constant temperature bath at 80±1°C, and when the conductor was immersed in the sodium sulfide aqueous solution for 30 seconds, the plasticizer was removed.
It was eaten away by the PVC composition and lost its resistance to sulfur oxides, resulting in discoloration. Regarding imidazole, we prepared a corrosion-inhibiting coating liquid in the same manner as described above using the composition shown in Table 2, obtained an insulated core wire P, and conducted the above-mentioned tests. It worked.

【table】

〔effect〕

Since the present invention is configured as described above, the contained plasticizer is non-migratory, for example,
When applied as a sulfur oxide resistant agent to the conductor of a PVC insulated wire, the conductor's resistance to sulfur oxide is maintained and corrosion is effectively inhibited. Therefore, according to the present invention, for example, it is possible to obtain an insulated wire that is highly reliable over a long period of time, and corrosion of metal having a PVC composition film is effectively prevented.

[Brief explanation of drawings]

The drawing is a partially cutaway perspective view of an example in which the anti-corrosion coating according to the present invention is used for an insulated wire. 1... Hard copper wire, 2... Conductor, 3... Insulator (PVC composition), a... Corrosion prevention coating (diluted stock solution), P... Insulated wire.

Claims (1)

[Claims] 1. A corrosion-inhibiting coating for metals having a film of a vinyl chloride composition consisting of a reaction product of triazoles or imidazoles and an epoxy plasticizer.