JPS6124768B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to an improved method of manufacturing crosslinked rubber and plastic insulated wire and cable. Conventionally, the method for manufacturing this type of insulated wire cable is to feed rubber or plastic to a screw extruder, and then directly inject a crosslinking agent or a mixture of a crosslinking agent and an anti-aging agent from a part of the extrusion barrel of the extruder. There is a known method of press-fitting, kneading with rubber or plastic in an extruder, extruding this as it is onto a conductor or cable core, and then heating and crosslinking to produce a crosslinked rubber or plastic insulated wire cable. There is. However, in such conventional technology, when a mixed solution of a crosslinking agent and an anti-aging agent is injected under pressure, the anti-aging agent is not completely dissolved in the cross-linking agent, which may cause clogging of pipes, pumps, etc. ,
There were also problems such as non-uniform dispersion. 4,4'-thiobis-(6-tert-butyl-3-methylphenol), which is commonly used as an anti-aging agent for cross-linked rubber and plastic insulated wire cables, has poor solubility in cross-linking agents. The crosslinking agent must be brought to a fairly high temperature for complete dissolution. This increases the risk and requires operational maintenance on the extruder. In addition, there was a drawback that the crosslinking efficiency decreased due to thermal decomposition of the crosslinking agent due to the high temperature. An object of the present invention is to provide a method for manufacturing a crosslinked rubber/plastic insulated wire cable that can eliminate the above-mentioned drawbacks and safely and easily improve the crosslinking efficiency. That is, as a result of intensive research into a method for press-feeding a crosslinking agent and anti-aging agent into an extruder, the present inventors discovered that 4,4'-thiobis-(6-tert-butyl-3-methylphenol), a general-purpose anti-aging agent, ) and then heated to react the radical generator with 4,4′-thiobis-(6-tert-butyl-3-methylphenol), and the reaction product obtained is a crosslinking agent. becomes very soluble. Therefore, it easily dissolves a crosslinking agent that is liquid at room temperature without heating, and it easily dissolves a crosslinking agent that is solid at room temperature at its melting point. Therefore, we discovered that it is possible to successfully press rubber or plastic into an extruder at a low temperature, which solves all the operational problems encountered with conventional methods at once. The present invention was completed based on the discovery that a crosslinked rubber/plastic insulated wire/cable can be produced with crosslinking efficiency superior to conventional methods by coating and then crosslinking. That is, the present invention provides 4,4'-thiobis-(6-
By reacting tert-butyl-3-methylphenol with a radical generator,
4,4′-Thiobis-(6-tert-butyl-
3-methylphenol) into a reaction product that is easily soluble in a crosslinking agent, and can be used to safely and easily inject the crosslinking agent into an extruder for operation. It is also characterized by being able to suppress a decrease in crosslinking efficiency. In other words, the present invention involves press-injecting a crosslinking agent into rubber or plastic in an extruder, kneading it with the rubber or plastic, and extrusion coating the crosslinking agent onto a conductor or core.
Then, when crosslinking is carried out by heating to produce a crosslinked rubber or plastic insulated wire cable, a radical generator is reacted with 4,4'-thiobis-(6-tert-butyl-3-methylphenol) as a crosslinking agent. The method is characterized by using a crosslinking agent in which the reaction product obtained by the above method is dissolved and mixed. Therefore, the radical generators used herein include dicumyl peroxide, ditertiary butyl peroxide, tertiary butyl mil peroxide, α-α′-bis(tertiary butyl peroxy) paradiisopropylbenzene, benzoyl peroxide, Organic peroxides such as methyl ethyl ketone peroxide can be used. Also, 4,
4′-thiobis-(6-tert-butyl-3-
The amount of the radical generator reacted with methylphenol is preferably 0.1 to 50% by weight based on the compound. Further, the rubber or plastic used here includes polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, styrene-butadiene copolymer, etc., and any rubber or plastic that can be crosslinked may be used. Furthermore, as the crosslinking agent, dicumyl peroxide, ditertiary butyl peroxide,
Tertiary butyl cumyl peroxide, 2,
5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,
Examples include organic peroxides such as 5-di(tert-butylperoxy)hexyne-3. Among these crosslinking agents, those that are solid at room temperature must be heated to their melting point to become liquid. EXAMPLES The present invention will be described in more detail below with reference to Examples and in comparison with Comparative Examples. Example 1 10% by weight of dicumyl peroxide (hereinafter abbreviated as DCP) was added to 4,4'-thiobis-(6-tert-butyl-3-methylphenol), and the mixture was mixed at a temperature of 160°C. React in nitrogen gas for 30 minutes. This was returned to room temperature, and the resulting reaction product was dissolved at 15% by weight in DCP at a temperature of 45°C. This solution was injected into the polyethylene in the extruder from the compression section of the extruder, and after kneading, it was extruded onto a conductor. A 6KV250sq crosslinked polyethylene insulated cable was manufactured by coating, heating and crosslinking. Table 1 shows the manufacturing results and the cable characteristics obtained.
As can be seen from comparison with comparative examples (described later), the remarkable effects of the present invention were observed. Example 2 20% by weight of tert-butyl cumyl peroxide was added to 4,4'-thiobis-(6-tert-butyl-3-methylphenol), mixed and heated with nitrogen gas at a temperature of 170°C for 20 minutes. Heat the reaction inside. A 6KV250sq cross-linked polyethylene insulated cable was prepared in the same manner as in Example 1, except that the resulting reaction product was dissolved at 10% by weight in tert-butylcumyl peroxide at a temperature of 20°C. We made a prototype. Table 1 shows the manufacturing results and the cable characteristics obtained. As can be seen from comparison with Comparative Examples (described later), remarkable effects of the present invention were observed. Comparative example 1 4,4′-thiobis-(6-tert-butyl-3-methylphenol) was added to DCP at a temperature of 45°C for 15 minutes.
A cross-linked polyethylene insulated cable of 6KV250sq was manufactured using this mixture in the same manner as in Example-1. Table 1 shows the manufacturing results and the cable characteristics obtained. Comparative Example 2 The same procedure as in Example 1 was carried out except that 0.05% by weight of DCP was added to 4,4′-thiobis-(6-tert-butyl-3-methylphenol) and this mixture was used as it was. A cross-linked polyethylene insulated cable was manufactured. Table 1 shows the manufacturing results and the cable characteristics obtained. Comparative example 3 4,4′-thiobis-(6-tert-butyl-3-methylphenol) was added to DCP at a temperature of 80°C for 15 minutes.
A cross-linked polyethylene insulated cable of 6KV250sq was manufactured using this mixture in the same manner as in Example-1. The results are shown in Table-1.

[Table] As mentioned above, 4,4′-thiobis-(6-
A complete solution of tert-butyl-3-methylphenol (tert-butyl-3-methylphenol), which can be easily dissolved in a cross-linking agent without impairing its effect as an anti-aging agent, has been reactively modified and dissolved in a cross-linking agent. The method of the present invention, which is carried out by injection into a machine, is safer and easier to operate than the conventional method, and has the effect of improving crosslinking efficiency, so the method of the present invention is industrially useful.

Claims (1)

[Claims] 1. A mixture of a cross-linking agent and an anti-aging agent is press-injected into rubber or plastic in an extruder, kneaded with the rubber or plastic, extruded and coated onto a conductor or core, and then heat-linked to produce cross-linked rubber or cross-linked plastic. In producing insulated wire cables, as a mixture of crosslinking agents, anti-aging agents,
4,4′-Thiobis-(6-tert-butyl-
1. A method for producing a crosslinked rubber/plastic insulated wire and cable, which comprises using a mixture of a reaction product obtained by reacting (3-methylphenol) with a radical generator and dissolved in a crosslinking agent.