JPS5938715B2 - Insulation treatment method for cable connections - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for insulating cable connections.

Insulation of cable connections, where cables are connected by soldering or cables are connected to electric wires, is carried out by wrapping adhesive tape or covering the cables with heat-shrinkable tubes.

These methods are effective and simple when applied to low-voltage, low-current equipment, but cannot provide sufficient insulation properties for the joints in high-voltage, high-current equipment. The method used to insulate the cable connections of high-voltage, high-current equipment is to wrap unvulcanized rubber tape or uncured prepreg tape to the required thickness and then harden it using an appropriate heating and pressure device. ing.

In this case, it is necessary to wrap the tape over every detail so that the internal voids are minimized, and it also needs to be wrapped to fit the mold, which takes an extremely long time even for experienced workers. . Furthermore, even with the utmost care, boards remain between the tapes, causing dielectric breakdown in a short period of time in harsh environments such as high humidity and dust. Furthermore, a heating and pressurizing device is required for curing, and the size of the mold needs to be increased in accordance with the pressurization.

Therefore, cables are used to connect the installed electrical equipment,
This significantly reduces work efficiency when insulating the connection portions. As described above, insulating cable connections using conventional methods involves many processing steps, each step takes a relatively long time, and it is almost impossible to introduce automation, so it must be done manually. Must be.

Furthermore, since there are many variations in the reliability of the insulation in the treated connection parts, it takes a lot of time to perform more insulation treatment than necessary. As a result of extensive research to overcome the above-mentioned problems, the inventors of the present invention discovered a method for insulating cable connections that shortens working time, simplifies the previous work, and provides high reliability. I've come to the point where I can complete it.

That is, the present invention provides a prepolymer having a terminal hydroxyl group consisting of a hydrogenated product of a polyhydroxybutadiene polymer having a melting point of 40 to 130°C and a solid at room temperature and an isocyanate compound, and a prepolymer having a terminal hydroxyl group represented by formula (1): (1'). , preforming a molding material made of 4-toluene diisocyanate dimer into a predetermined shape, placing the preformed molded product and a cable connection part in a mold equipped with a curing heater, and heating and melting it, The present invention relates to a method for insulating a kettle connection portion which is then hardened.

The prepolymer having terminal hydroxyl groups, which is obtained by reacting 2.0 to 2.5 moles of a hydrogenated polyhydroxybutadiene polymer with 1 mole of an isocyanate compound, which is the main ingredient of the molding material used in the present invention, is a thermosetting resin. The ratio of this base resin to the 2,4-toluene diisocyanate dimer represented by formula (1), which is a curing agent, is such that the number of moles of isocyanate groups in the curing agent is NCO/OH relative to the number of moles of hydroxyl groups in the base resin. It is preferable that the ratio is 0.8 to 1.2. The thermosetting resin used for the molding material has a melting point within the above range, and the molding material consisting of the base resin and curing agent has a pot life of 1 month or more (depending on the melting point temperature) when stored at room temperature or at a low temperature below 0°C. Flowing). If the melting point of the hydrogenated polyhydroxybutadiene polymer used in the present invention is lower than 40°C, it will tend to flow at room temperature and will not be able to maintain its preformed shape, and will have stickiness that will significantly reduce workability. do.

On the other hand, if it is higher than 130° C., the melting temperature during molding becomes high, and a gelation reaction occurs during melting, resulting in poor appearance such as resin missing parts or remaining boards, which is not preferable. The preformed molded product according to the present invention is placed inside a mold so as to cover the cable connection portion, and then heated and hardened.

Further, during heat curing, the sum of the volumes of the preformed molded product and the cable connection part must be equal to or larger than the volume of the hollow part of the mold so that a board does not form inside. Since the mold only needs to be heated by placing a preformed molding material therein for covering the cable connection, a relatively simple structure is sufficient. Next, the method of the present invention will be explained in detail based on the drawings, but the present invention is not limited thereto.

Fig. 1 is an explanatory diagram of the cable connection part to be insulated in the present invention, Fig. 2 is an explanatory diagram of the method of preforming the molding material, Fig. 3 is a plan view when the mold is opened, and Fig. 4 is FIG. 5 is a partial cross-sectional view of the mold when the preformed molding material is put in and the mold is closed, and FIG. 5 is a process explanatory diagram of the insulation treatment method of the present invention.

In FIG. 1, 1 is an electric wire, 3 is a cable wire, and 2 is a joint obtained by soldering these.

Figure 2 is an explanatory diagram of the method of preforming the molding material, 4 is a normal vacuum stirring device, 5 is a melting point of 40 to 130
This indicates a molding material consisting of a thermosetting resin main resin and a curing agent within the range of °C. Reference numeral 6 indicates a mold for the preform, but a plastic case with excellent mold releasability may be used in place of the mold.

A molding material which has been sufficiently degassed at a temperature above the melting point by a vacuum stirring device is injected into a preform mold 6, and then cooled to room temperature and the mold is removed to obtain a preformed molded article 7. In this example, the molding material 5 is a hydrogenated material of polyhydroxybutadiene polymer as the main ingredient 2.
The number of moles of the curing agent is adjusted to be equal to the number of moles of hydroxyl groups in the prepolymer having terminal hydroxyl groups, which is obtained by reacting 3 moles of 2,4-toluene diisocyanate dimer with 1 mole of 2,4-toluene diisocyanate dimer.

Fig. 3 is a plan view when the two-part mold used in the present invention is opened, and 8 is the mold body, 9 is a mold clamping bolt, 10 is a hinge, and 11 is a cable line that is misaligned when it is set. 12 is a lead wire of the heater.

FIG. 4 shows a partial cross-sectional view of the mold when a preformed molded product is put therein and the mold is closed, and 13 is a heater. FIG. 5 is a process explanatory diagram of the insulation treatment method of the present invention.
An example of the procedure of the processing method of the present invention is as follows.

That is, the voltage of the heater is adjusted to preheat the mold to the melting point of the molding material. Next, the molding material and the cable connection portion to be insulated are quickly set in the mold, the mold is clamped, and the molding material is melted. The mold clamping force is extremely weak, and for example, it is sufficient to manually tighten a fastener attached to the mold. Thereafter, heat curing is performed at 140 to 160°C for 1 to 2 hours. By demolding after curing, insulation treatment of the cable connection portion is achieved. Since the cable connection insulation treatment method of the present invention is performed by integral melt molding, boards that occur in conventional taping work are not generated, and it can be used even under harsh environments such as high humidity and high dust. Highly reliable insulation treatment is possible.

Furthermore, the working time can be surprisingly shortened, and workability can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the cable connection part to be insulated in the present invention, Fig. 2 is an explanatory diagram of the method of preforming the molding material, Fig. 3 is a plan view when the mold is opened, and Fig. 4 is FIG. 5 is a partial cross-sectional view of the mold when the preformed molding material is put in and the mold is closed, and FIG. 5 is a process explanatory diagram of the insulation treatment method of the present invention. Symbols in drawings: 1: electric wire, 2: joint, 3: cable line,
4: Vacuum stirring device, 5: Molding material, 6: Preform mold, 7: Molded product, 8: Mold, 9: Mold clamping bolt, 10
: Hinge, 11: Cable wire fixing fitting, 12: Curing heater lead wire, 13: Curing heater.

Claims (1)

[Claims] 1 A prepolymer with a terminal hydroxyl group consisting of a hydrogenated polyhydroxybutadiene polymer and an isocyanate compound with a melting point of 40 to 130°C and solid at room temperature, and formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼( I)
A molding material made of 2,4-toluene diisocyanate dimer shown by is preformed into a predetermined shape, and the preformed molded product and the cable connection part are placed in a mold equipped with a curing heater. A method for insulating cable connections, which comprises heating, melting, and then hardening.