JPH09204834A - Manufacture of electric wire having water stop function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture electric wires having a good water stop function at a low cost without provision of any special water stopping means between a conductor and an insulative substance and without subjecting to a special shaping process. SOLUTION: An insulative inner layer 3 and an insulative outer layer 4 are furnished around conductors 1, 2. The inner layer 3 is fed with an excessive amount of plasticizer, and the watercourse in the electric wire is choked with the plasticizer 5 oozing from the inner layer 3 to the conductor surfaces. An inorganic filler absorbing the plasticizer 5 transferring from the inner layer 3 is added to the outer layer 4 so that the plasticizer 5 is prevented from oozing to the surface of the electric wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric wire with a waterproof function used for a wire harness for an automobile.

[0002]

2. Description of the Related Art Generally, in an electric wire used for a wire harness for an automobile or the like, water such as rain water may enter from a soldering portion, a branch connecting portion, an earth terminal or the like. In this case, if no measures are taken to the electric wire, there is a possibility that a so-called water running phenomenon may occur in which the water content is transmitted through the gap between the conductor and the insulator over a long distance in the electric wire length direction. In this way, the moisture transmitted in the cable may change the signal transmission characteristics of the cable, and in the worst case, may corrode the external conductor or the connector parts of the terminal, and eventually cause a defective electrical contact.

Therefore, conventionally, a watertight compound containing an acrylic copolymer or the like as a main component is filled between the conductor and the insulator so that the watertight compound is closely adhered to the periphery of the conductor to close the water channel inside the insulator. Watertight electric wires have been provided.

[0004]

In the above electric wire, between the conductor and the insulator, it is necessary to fill a special water-tight compound having basically different components from those of the conductor and the insulator. Moreover, in order to surely adhere the watertight compound to the conductor surface, a considerable pressure must be applied from the outside in the radial direction at the time of molding, and special equipment and processes therefor are required. Therefore, this electric wire has a disadvantage that the cost is significantly higher than that of an ordinary electric wire.

Japanese Patent Laid-Open No. 168911/1988 discloses an electric wire in which a plasticizer is added to the above watertight compound. The amount of the plasticizer added varies from the outer insulator to the watertight compound. Only blocking the transfer of the plasticizer does not cause bleeding of the plasticizer from the watertight compound to the inner conductor, and does not particularly affect the water-stop function. Further, the watertight compound is composed of a special component different from the insulator on the outside, and a special step is still required to bring this into close contact with the conductor, and it is possible to avoid an increase in cost. Can not.

In view of such circumstances, the present invention provides an electric wire having a good water-stopping function without specially providing water-stopping means between the conductor and the insulator and without special molding. It is an object to provide a method that can be manufactured at a cost.

[0007]

Generally, a plasticizer is blended in the insulator of the electric wire, but the present inventors have found that the plasticizer oozes out to the inside (that is, the conductor side) to form a conductor. The idea was to block the surrounding space and exert a so-called water-stop function. However, if this plasticizer oozes out onto the surface of the electric wire, it becomes difficult to use, and it is necessary to prevent the oozing out onto the surface of the electric wire.

The present invention has been made from such a point of view, in which an inner layer of an insulator having a base material made of a synthetic resin and an outer layer of the insulator are formed around the conductor, and the inner layer of the insulator is plastic. The agent is excessively blended, and the inorganic filler that absorbs the plasticizer is blended only in the outer layer of the insulator, and the space around the conductor is filled with the plasticizer leached from the inner layer of the insulator to the conductor side. It was designed to close the.

Here, the "excessive plasticizer" means a plasticizer in such an amount that bleeding (bleeding) occurs at least inside (that is, the conductor side) from the in-insulator layer, and this bleeding occurs. The so-called water running phenomenon inside the insulator can be prevented by the plasticizer. Moreover, the plasticizer that has migrated from the inner layer of the insulator to the outer layer of the insulator is absorbed by the inorganic filler added to the outer layer of the insulator, so that the plasticizer is prevented from seeping out to the surface of the insulator.

In this method, as the materials for the inner and outer layers of the insulator, the plasticizer, and the inorganic filler, the same materials as those used in ordinary electric wires can be used.
The above-mentioned preferable effect can be obtained only by changing the mixing ratio.

More specifically, polyvinyl chloride is suitable as the base material for the inner and outer layers of the insulator, and its degree of polymerization is 80.
It is preferable to set in the range of 0 to 3000 (more preferably 1000 to 2500). As the plasticizer for polyvinyl chloride, a phthalic acid-based plasticizer, a polyethylene-based plasticizer, or the like is suitable.

As the phthalic acid type plasticizer, it is extremely preferable to use one having a carbon number of 7 or more and 10 or less.
If the carbon number is less than 7, the heat resistance is insufficient, and conversely, if the carbon number is more than 10, even if it is blended in the inner layer of the insulator, it does not exude well from the same layer to the inner conductor. This is because there is a risk.

In order to surely exude such a phthalic acid-based plasticizer from the insulator inner layer to the conductor, the phthalic acid-based plasticizer is added to 100 parts by weight of the base material (that is, polyvinyl chloride) of the insulator inner layer. 70 parts by weight of the agent (more preferably 8
It is important to add 0 part by weight). However, if this phthalate plasticizer is added too much, the inner layer of the insulator will bite into the conductor severely and the workability will deteriorate when used in a wire harness, etc. 150 parts by weight or less (more preferably 120
It is recommended to set it to less than 1 part by weight.

If liquid chlorinated paraffin (that is, chlorinated paraffin having a chlorination rate of about 50% or less) is added to this phthalic acid-based plasticizer, the minimum blending ratio of the plasticizer required for exudation to occur. Go down. Specifically, 30 to 60 parts by weight of a phthalic acid-based plasticizer having 7 to 10 carbon atoms and 30 to 70 parts by weight of chlorinated paraffin are added to 100 parts by weight of the base material of the insulator inner layer. By doing so, the plasticizer can be sufficiently exuded to the conductor by adding 60 parts by weight or more (more preferably 70 parts by weight or more) of the mixture of the phthalic acid type plasticizer and the chlorinated paraffin. Also, by setting the blending ratio of the above mixture to 130 parts by weight or less (more preferably 100 parts by weight or less), it is possible to avoid the penetration of the in-insulator layer into the conductor.

Here, the compounding ratio of the phthalic acid type plasticizer is 30
The reason why the content of the chlorinated paraffin is 30 parts by weight or more is because if the content is less than 30 parts by weight, the required electric wire characteristics (mainly heat resistance) cannot be obtained. The reason why the amount is not less than 10 parts is that if the compounding ratio is less than 30 parts by weight, sufficient exudation of the plasticizer may not be expected.

When the polyester type plasticizer of (1) is used,
Although leaching to the inner conductor cannot be expected by itself, the leaching can be excited by allowing a lead-based stabilizer to coexist therewith.

Specifically, in the insulator inner layer, 50 parts of the polyester plasticizer is added to 100 parts by weight of the base material.
If it is blended in an amount of at least parts by weight, the exudation can be expected, and by setting the blending ratio to be not more than 150 parts by weight, it is possible to avoid the penetration of the insulator inner layer into the conductor.
Moreover, since this polyester-based plasticizer is also excellent in heat resistance, it is possible to provide an electric wire that can be used even in a portion where the ambient temperature is high.

The above-mentioned lead-based stabilizer may be any one as long as it can prevent the base material polyvinyl chloride from being hardened by thermal decomposition during the molding of the insulator and maintain the plasticity, and specifically, tribasic sulfuric acid. Lead, dibasic lead phosphite, dibasic lead phthalate,
Lead stearate, lead phosphite and the like are preferable. By adding such a lead-based stabilizer in an amount of 2 parts by weight or more based on 100 parts by weight of the base material of the insulator inner layer, excellent extrusion molding of the insulator can be realized. However, if the addition rate of the lead-based stabilizer exceeds 12 parts by weight, the polyester-based plasticizer may excessively exude and reduce the terminal crimpability, so the addition rate is set to 12 parts by weight or less. Is preferred.

In any of the above cases, in order to reliably prevent the plasticizer from seeping out from the inner layer of the insulator to the outer insulator surface,
It is important to mix 30 parts by weight or more (more preferably 50 parts by weight or more) of the inorganic filler with 100 parts by weight of the base material in the outer layer of the insulator. As the inorganic filler, calcium carbonate, magnesium hydroxide, aluminum hydroxide and the like can be preferably used.

The plasticizer added to the outer layer of the insulator may be any plasticizer that functions as an original plasticizer. In addition to the above-mentioned phthalic acid-based plasticizers and polyester-based plasticizers, trimellitic acid-based plasticizers. Alternatively, a pyromellitic acid plasticizer may be used.

[0021]

1 (a) and 1 (b) show an electric wire C with a water stop function manufactured by the method described in the above section "Means for Solving the Problems". In the figure,
A plurality of stranded wire conductors 2 are twisted around the central conductor 1 to form a conductor according to the present invention. Then, the insulator inner layer 3 and the insulator outer layer 4 are provided around the conductor.
And a plasticizer 5 excessively incorporated into the in-insulator layer 3
Is exuded on the surface of the inner stranded wire conductor 2 (Fig. 1
(Only (b) is shown). The plasticizer 5 closes the gap between the stranded wire conductor 2 and the in-insulator layer 3, so that the so-called water running phenomenon through the gap is prevented.

1 (a) and 1 (b), for the sake of convenience, the insulator inner layer 3 and the insulator outer layer 4 are shown as being completely independent from each other, but in reality, both layers 3 and 4 are formed. The base materials are equivalent to each other, and both layers 3 and 4 are in a substantially integrated state. Both layers 3 and 4 can be easily formed by simple extrusion molding like an insulator in an ordinary electric wire, and like a conventional electric wire with a water-stop function, a watertight compound is formed by applying pressure from the outside. There is no need for a special process such as contacting the surface.

In FIG. 1A, the ratio t ₃ / t of the thickness t ₃ of the in-insulator layer 3 to the thickness t of the entire insulator may be set appropriately, and specifically, it is preferably 40 to 80%. .

Further, in the present invention, regardless of the specific shape and structure of the conductor, it can be widely applied to various electric wires whose periphery is covered with an insulator.

[0025]

EXAMPLES The present inventors have conducted three examples of the present invention.
The water-stopping performance test and the presence / absence of bleeding of the plasticizer on the surface of the electric wire were carried out for each of the two types and Comparative Examples. The structure of each example is as follows.

Example: A base material 1 made of polyvinyl chloride having a degree of polymerization of 1300 in an insulator inner layer (thickness 0.2 mm)
8 parts by weight of DOP as a phthalic acid-based plasticizer
0 parts by weight, 4 parts by weight of tribasic lead sulfate as a stabilizer, and 0.5 parts by weight of lead stearate as a lubricant, respectively. In the outer layer of the insulator (thickness 0.1 mm), DO was added to 100 parts by weight of the base material made of polyvinyl chloride having a degree of polymerization of 1300.
30 parts by weight of P and 60 parts of inorganic filler (calcium carbonate)
Only part by weight. The same as the inner layer for stabilizers and lubricants.

Example: A base material 1 made of polyvinyl chloride having a degree of polymerization of 1300 in an insulator inner layer (thickness 0.2 mm)
3 parts by weight of DOP as a phthalic acid-based plasticizer to 100 parts by weight.
0 parts by weight, 50 parts by weight of chlorinated paraffin, 4 parts by weight of tribasic lead sulfate as a stabilizer, and 0.5 parts by weight of lead stearate as a lubricant, respectively. Outer insulation layer (wall thickness
0.1 mm) is the same as the example.

Example: Base material 1 made of polyvinyl chloride having a degree of polymerization of 1300 in the inner layer of the insulator (thickness: 0.2 mm)
80 parts by weight of polyester plasticizer, 50 parts by weight of chlorinated paraffin, 4 parts by weight of tribasic lead sulfate as a stabilizer, and 0.5 parts by weight of lead stearate as a lubricant, respectively, per 00 parts by weight. . Outer insulation layer (wall thickness 0.1 m
For m), the same as in the example.

Comparative Example: Different from Examples 1 to 3, the insulator is a single layer, and the thickness of the entire insulator is the same as in Examples 1 to 3.
0.3mm A degree of polymerization of 1 over the entire insulation
80 parts by weight of DOP is mixed with 100 parts by weight of the base material made of 300 polyvinyl chloride. No inorganic filler is added. The stabilizer and the lubricant are the same as those in Examples 1 to 3.

Comparative Example: As in the comparative example, the thickness of the insulator is increased.
Use a single layer of 0.3 mm. 80 parts by weight of DOP and 60 parts by weight of an inorganic filler (calcium carbonate) were mixed with 100 parts by weight of a base material made of polyvinyl chloride having a degree of polymerization of 1300, all over the insulator. The stabilizer and the lubricant are the same as those in Examples 1 to 3.

The waterproof performance test was conducted using the apparatus shown in FIG. In the figure, the cylinder 10 is connected to one end of the electric wire C in a watertight state, the water 12 in the cylinder 10 is pressurized by the piston 14 to 98 kPa, and the length L of water soaked in the electric wire C at this time is measured. It can be said that the smaller the water immersion length L is, the more excellent the waterproof performance is.

The contents of each of the above examples and the test results are summarized in Tables 1 to 3 below.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

As shown in each table, in each of Examples 1 to 3, it can be understood that the water immersion length L is as short as 3 mm and that the water blocking performance is good. It can be considered that this is because the plasticizer is sufficiently exuded inside the insulator layer, and the gap around the conductor is closed by the plasticizer. Moreover, since the outer layer of the insulator is filled with an appropriate amount of the inorganic filler, the plasticizer bleeds to the surface of the outer layer.
Is completely prevented.

On the other hand, in the comparative example, the water immersion length L is relatively short at 4 mm, and although the water stopping performance is not so much in comparison with the examples 1 to 3, the plasticizer oozes out to the surface of the electric wire. It can be considered that this is because the insulator is not filled with the inorganic filler that absorbs the plasticizer.

On the contrary, in the comparative example, bleeding of the plasticizer on the surface of the electric wire did not occur, but water was flooded over the entire length (300 mm) of the electric wire, and almost no waterproof performance was obtained. This is because the inorganic filler is mixed throughout the insulator, so even if an excessive amount of plasticizer is added to the insulator, the plasticizer will be absorbed by the inorganic filler and the conductor surface will be plasticized. It can be considered that this is because the agent does not exude.

From the above results, in order to obtain good water stopping performance by exuding the plasticizer and prevent the bleeding of the plasticizer on the surface of the electric wire, the insulator is divided into the inner layer and the outer layer, and only the inner layer is used. It can be seen that it is important to incorporate an excess of plasticizer so that only the outer layer contains an inorganic filler for plasticizer absorption.

[0040]

As described above, according to the present invention, the insulator is divided into the inner layer and the outer layer, and the excess plasticizer is blended in the inner layer, while the inorganic filler absorbing the plasticizer is blended in the outer layer. Since the plasticizer is exuded only to the inside of the insulator to block the water channel with this plasticizer, the water-stopping performance can be achieved without using any special watertight compound or introducing any special process. In addition, there is an effect that it is possible to manufacture an electric wire which is excellent in heat resistance and has no plasticizer oozing out to the surface at low cost.

[Brief description of drawings]

FIG. 1A is a sectional front view showing an example of an electric wire with a water stop function manufactured by the method of the present invention, and FIG. 1B is a sectional side view showing the electric wire.

FIG. 2 is a cross-sectional view showing an outline of a test apparatus used for a water blocking performance test of Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 1 center conductor 2 stranded conductor 3 insulator inner layer 4 insulator outer layer 5 plasticizer

Claims (8)

[Claims] 1. An in-insulator layer having a synthetic resin base material and an insulative outer layer are formed around a conductor, and a plasticizer is excessively mixed only in the in-insulator layer to form an insulative outer layer. Incorporating an inorganic filler that absorbs the above plasticizer,
A method of manufacturing a wire with water stop function, characterized in that a space around the conductor is closed by a plasticizer oozing from the inner layer of the insulator to the conductor side. 2. The method for producing an electric wire with a water stop function according to claim 1, wherein polyvinyl chloride is used as a base material for the inner and outer layers of the insulator. 3. The method for producing an electric wire with a water blocking function according to claim 2, wherein the number of carbon atoms is 7 as a plasticizer for the inner layer of the insulator.
A method for producing an electric wire with a water stop function, which comprises using 10 or more and 10 or less phthalic acid-based plasticizers. 4. The method of manufacturing an electric wire with a water stop function according to claim 3, wherein the phthalic acid plasticizer is mixed around the conductor in an amount of 70 to 150 parts by weight with respect to 100 parts by weight of the base material. A method of manufacturing a wire with water-stopping function, comprising forming an inner layer and an outer layer of an insulator in which 30 parts by weight or more of an inorganic filler is mixed with 100 parts by weight of the base material. 5. The method of producing a wire with water stop function according to claim 3, wherein liquid chlorinated paraffin is added to the inner layer of the insulator in addition to the phthalic acid plasticizer. Manufacturing method of attached electric wire. 6. The method of manufacturing an electric wire with a water stop function according to claim 5, wherein only 30 to 60 parts by weight of the phthalic acid-based plasticizer is compounded around the conductor with respect to 100 parts by weight of the base material. 30 to 70 parts by weight of chlorinated paraffin was added to the phthalate plasticizer and chlorinated paraffin so that the total amount was 60 to 130 parts by weight, and 100 parts by weight of the above base material. And 30% by weight or more of an inorganic filler are mixed together to form an outer layer of an insulator. 7. The method of manufacturing an electric wire with a waterproof function according to claim 2, wherein a polyester-based plasticizer is used as a plasticizer for the insulator inner layer, and a lead-based stabilizer is added to the insulator inner layer. And a method of manufacturing a wire with a waterproof function. 8. The method for producing an electric wire with water stop function according to claim 7, wherein only 50 to 150 parts by weight of a polyester plasticizer is mixed around the conductor with respect to 100 parts by weight of the base material, and a lead system is used. A water-stop function comprising forming an in-insulator layer containing only 2 to 12 parts by weight of a stabilizer and an outer insulator layer containing 30 parts by weight or more of an inorganic filler with respect to 100 parts by weight of the base material. Manufacturing method of attached electric wire.