JPH08222035A - Ultraviolet-ray cross-linked foamed insulated wire and its manufacture - Google Patents

Abstract

PURPOSE: To effectively suppress the reduction in crosslinking density and perfectly eliminate the trouble by excessive emission of ionizing radiation by providing a foamed insulating layer consisting of a plurality of divided layers differed in foaming degree in an ultraviolet-ray cross-linked foamed insulated wire having an ultraviolet-ray cross-linked foamed layer on a conductor. CONSTITUTION: A thermally decomposing type foaming agent is added in an amount of 2 parts by weight and an amount of 3 parts by weight, respectively, to an ultraviolet-ray cross-linked resin obtained by adding 3 parts by weight of an acetophenone photopolymerization initiator to 80 parts by weight of an urethane acrylate oligomer and 20 parts by weight of a monomer having an acryloyl group to prepare a foamed composition A and a composition B. These materials are applied to a 42 ABG stranded wire (7/0.025). The resulting wire is passed in an electric furnace, and hardened by emission of ultraviolet ray. The thus-obtained ultraviolet-ray foamed insulated wire is formed of a conductor 1 consisting of a stranded wire conductor, an ultraviolet-ray cross-linked foamed insulating layer 2 of an inner layer, and an ultraviolet-ray cross-linked foamed insulating layer 3 of outer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet crosslinked foam insulated wire and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, there has been a strong tendency for miniaturization or high-density mounting in communication equipment and precision electronic equipment.

In order to meet these demands, the core wire of the cable tends to be further reduced in diameter, and the outer diameter is 0.5 mm.
Insulated electric wires with the following small diameters are becoming popular.

On the other hand, in computers and the like, there is a marked tendency to demand even higher speeds of transmission signals, and the insulating layer of the above-mentioned small-diameter insulated wire used for this is made thin and highly foamed so that it is as low as possible. There is an increasing demand for so-called high-speed wires, which are intended to speed up transmission signals by increasing the permittivity.

In order to further reduce the wall thickness under such a situation, a method has been developed in which an ultraviolet cross-linking resin, which is a liquid material, is applied instead of the conventional insulator using polyethylene or fluororesin. By foaming this ultraviolet-crosslinking resin, a thin high-speed wire with a low dielectric constant, that is, a high-speed transmission signal is obtained.

As a method of foaming the ultraviolet cross-linking resin, there are disclosed in Japanese Patent Laid-Open No. 2-160312 or Japanese Patent Laid-Open No. 2-291609.
No. 3-27517, or by incorporating a hollow sphere as described in JP-A-3-267712, or by further thermally expanding it.
As in No. 7, there is a method of using a foaming agent.

As described above, the ultraviolet-crosslinking resin is a liquid material and is suitable for a thin-walled insulator, and by foaming this, a thin-walled foam insulated wire can be obtained. However, in a method such as JP-A-3-275177 using a chemical foaming agent, the foaming gas is easily released, so that the foaming agent is added more than necessary. Radicals are generated due to the decomposition of the foaming agent, and the radicals are excessive as a whole. The excess radicals reduce the crosslink density of the resin. Therefore, excessive irradiation is performed to supplement the crosslink density, and the high-speed productivity, which is an advantage of the UV crosslinkable material, is sacrificed.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and an object thereof is to solve the above-mentioned drawbacks of the prior art and to add foam to an ultraviolet-crosslinking foam insulating layer. The amount of agent added is small, which can significantly reduce the amount of radicals generated during foaming, which effectively suppresses the reduction in crosslinking density and eliminates the harmful effects of excessive irradiation of ionizing radiation. It is to provide a foam insulated wire and a manufacturing method thereof.

[0009]

The gist of the present invention lies in the following four points.

An ultraviolet-crosslinking foam insulation wire, comprising an ultraviolet-crosslinking foam insulation layer provided on a conductor, wherein the ultraviolet-crosslinking foam insulation layer is composed of a plurality of divided layers having different foaming degrees. Electrical wire.

An ultraviolet cross-linking foam insulating layer composed of a plurality of divided layers having different degrees of foaming is provided on a conductor, and an ultraviolet cross-linking resin layer is provided on the ultraviolet cross-linking foam insulating layer. Foam insulated wire.

An ultraviolet-crosslinking foam insulation characterized in that after continuously coating two or more kinds of ultraviolet-crosslinking resin paints containing an ultraviolet-crosslinking resin and a pyrolytic foaming foaming agent, the coating is irradiated with ultraviolet rays and then heated and foamed. Electric wire manufacturing method.

After continuously coating two or more kinds of UV-crosslinking resin paints containing the UV-crosslinking resin and the thermal decomposition type foaming agent, the UV-crosslinking resin paint is applied on the upper layer, and then pre-irradiated with UV rays. A method for producing an ultraviolet-crosslinked foamed insulated wire, which comprises heating from the inside, irradiating with ultraviolet rays, and finally heating and foaming.

In the present invention, the conductive metal may be any one having conductivity and flexibility, such as copper, aluminum, iron,
There are silver, platinum, gold and the like, and alloys thereof, and alloys obtained by adding tin, zinc and the like to these may also be used.

The shape of the conductor may be a single wire or a twisted wire, and the twisted wire may be a single wire or a single plated wire.

The ultraviolet-crosslinking resin composition used in the present invention basically comprises a photopolymerizable oligomer, a photopolymerizable monomer, a photoinitiator and the like.

Here, as the photopolymerizable oligomer (prepolymer), for example, epoxy acrylate type, epoxidized oil acrylate type, urethane acrylate type,
Polyester urethane acrylate type, polyether urethane acrylate type, polyester acrylate type,
Polyether acrylate type, vinyl acrylate type,
There are silicone acrylate type, polybutadiene acrylate type, polystyrene ethyl methacrylate type, polycarbonate dicarbonate type, unsaturated polyester type, polyene / thiol type and the like.

These oligomers are functional groups having an unsaturated double bond, such as acryloyl group, methacryloyl group,
It has two or more allyl groups and vinyl groups. The oligomer may be fluorine-substituted, and two or more kinds of oligomers may be combined.

As the photopolymerizable monomer, a known compound having one or more functional groups such as acryloyl group, methacryloyl group, allyl group and vinyl group in the molecule can be used.

The photopolymerization initiator has a function of initiating a polymerization reaction of a photopolymerizable oligomer or monomer and has a role of receiving a UV ray to generate a free radical. This free radical is necessary for ultraviolet curing, and the photopolymerization initiator is a substance that easily absorbs a specific wavelength by ultraviolet rays and becomes an electronically excited state to generate radicals. For example,
There are benzoin ether type, ketal type, acetophenone type, benzophenone type, thioxanthone type and the like, and various photopolymerization initiators can be used according to the purpose.

In carrying out the present invention, if desired, a photoinitiator aid, an adhesion preventive agent, a thixotropic agent, a filler, a plasticizer, a non-reactive polymer, a colorant, a flame retardant, a flame retardant aid, and a softening preventive agent. Agents, mold release agents, drying agents, dispersants, wetting agents, anti-settling agents, thickeners, antistatic agents, antistatic agents, fungicides, anti-mouse agents, anti-termite agents, matting agents, anti-blocking agents One or more agents such as agents, anti-skinning agents, and surfactants can be appropriately selected and added.

The following are representative examples of the foaming agent in the present invention, and it is possible to use one type or two or more types in combination. That is, any type of azo compound, dinitroso compound, hydrazide compound, carbazide compound or the like can be used as long as it generates gas by heat.

[0023]

The ultraviolet-crosslinked foamed insulated wire and the method for producing the same according to the present invention include, firstly, forming a low-foamed area and a high-foamed area by forming the ultraviolet-crosslinked foamed insulating layer into a plurality of layers having different foaming degrees. Can be provided arbitrarily. As a result, in the low-foaming region of the UV-crosslinked foamed insulation layer, it is possible to effectively prevent the escape and escape of the gas generated when the foaming agent is foamed to the outside, increasing the foaming efficiency, reducing the amount of foaming agent added, and radicals. The generation amount can be reduced, and the total crosslink density can be increased. In addition, the highly foamed region of the ultraviolet-crosslinked foamed insulation layer can improve the original purpose of lowering the dielectric constant.

Secondly, an ultraviolet-crosslinking foam insulating layer composed of a plurality of divided layers having different degrees of foaming is provided on the conductor, and an ultraviolet-crosslinking resin layer is provided on the ultraviolet-crosslinking foam insulating layer. By using the ultraviolet-crosslinked foamed insulated wire as described above, diffusion escape of gas generated when the foaming agent is foamed to the outside can be further suppressed, and mechanical strength can be further improved.

Thirdly, after continuously coating an ultraviolet-crosslinking resin coating material containing an ultraviolet-crosslinking resin and a thermal decomposition foaming type foaming agent, it is irradiated with ultraviolet rays and finally heat-foamed.
It is possible to efficiently produce the ultraviolet cross-linked foam insulated electric wire.

Fourthly, after continuously coating the UV-crosslinking resin coating material containing the UV-crosslinking resin and the pyrolytic foaming foaming agent, the UV-crosslinking resin coating material is coated on the upper layer, and then pre-irradiated with UV rays. The second UV-crosslinked and foamed insulated electric wire can be efficiently manufactured by heating from above and after-irradiating with ultraviolet rays.

[0027]

EXAMPLES Next, examples and comparative examples of the ultraviolet cross-linked foam insulated wire and the method for producing the same of the present invention will be described.

(Example 1) 80 parts by weight of urethane acrylate-based oligomer, monomer 20 having an acryloyl group
A foam composition comprising 2 parts by weight of a thermally decomposable foaming agent to an ultraviolet-crosslinking resin containing 3 parts by weight of an acetophenone-based photopolymerization initiator, and B a composition comprising 3 parts by weight of a foaming agent. And 42 AWG stranded wire (7 / 0.025) was coated with the above material using the coating apparatus of FIG.

At this time, the nipple had a diameter of 0.10 mm, a first die of 0.14 mm and a second die of 0.16 mm.
The coating pressure is 1.6 kg / cm ² for material B and 2.1 for material A.
It was kg / cm ² . The production speed was 100 m / min, and the foam was foamed by passing through an electric furnace having a total length of 80 cm and a temperature of 300 ° C., and was irradiated with ultraviolet rays to be cured.

The thickness of the foam layer produced under the above conditions was 35 μm for the inner foam layer and 15 μm for the outer foam layer.

FIG. 1 is a cross-sectional explanatory view of the thus obtained ultraviolet-crosslinked foam insulated electric wire of Example 1, wherein 1 is a conductor made of a stranded conductor and 2 is an inner layer of the ultraviolet-crosslinked foam insulated layer. Reference numeral 3 is an ultraviolet-crosslinked foam insulating layer which is an outer layer.

[0032] prepared in Example 2 above Example 1 using the same material and the die and, applying pressure to the material B 2.1 kg / cm ^2, the material A 1.8 kg / cm ^2. At this time, the thickness of the foam layer was 42 μm for the inner foam layer and 10 μm for the outer foam layer.

(Example 3) The inner layer was prepared by adding 3 parts by weight of a thermal decomposition type foaming agent (Wako Pure Chemical Industries, Ltd.) to 100 parts by weight of a fluorine acrylate-based UV-crosslinking resin (Dainippon Ink and Chemicals, Inc.), and an outer layer. In the above, 1 part by weight of a thermal decomposition type foaming agent was added based on a urethane acrylate-based UV cross-linking resin (electrochemical).

The first die pressure was 2.1 kg / cm ² and the second die pressure was 1.8 kg / cm ² , and the die diameters were φ0.14 mm and φ0.16 mm, respectively. A 42 AWG stranded wire (7 / 0.025) was used as a conductor, the linear velocity at this time was 90 m / min, and the foam was passed through an electric furnace having a total length of 80 cm and a temperature of 400 ° C.

The ultraviolet lamp used for pre-cure was a metal halide lamp with a glass filter that cuts wavelength components of 300 nm or more and irradiates only short wavelength components. Irradiation was performed with a metal halide lamp without using a filter during post cure.

The outer diameter of the electric wire manufactured under the above conditions is 195
The thickness of the inner layer was 50 μm, and the thickness of the outer layer was 10 μm.

(Example 4) 80 parts by weight of urethane acrylate-based oligomer, monomer 20 having an acryloyl group
A UV-crosslinking resin in which 3 parts by weight of an acetophenone-based photopolymerization initiator was added to parts by weight was designated as A, and a composition in which 3 parts by weight of a foaming agent was added to this resin was designated as B. 42 AWG stranded wire (7 /
0.025) was coated with the above material using the coating apparatus of FIG.

At this time, the nipple had a diameter of 0.10 mm, a first die of 0.14 mm and a second die of 0.16 mm.
The coating pressure is 1.6 kg / cm ² for material B and 2.1 for material A.
It was kg / cm ² . The production speed was 100 m / min, and the foam was foamed by passing through an electric furnace having a total length of 80 cm and a temperature of 300 ° C., and was irradiated with ultraviolet rays to be cured.

The thickness of the foam layer produced under the above conditions was 35 μm for the inner foam layer and 10 μm for the outer solid layer.

FIG. 2 is a cross-sectional explanatory view of the thus obtained ultraviolet-crosslinked foam insulated electric wire of Example 4, wherein 1 is a conductor made of a stranded conductor and 2 is an inner layer of the ultraviolet-crosslinked foam insulated layer. Reference numeral 4 is an outer layer of the UV-crosslinked insulating layer.

[0041] prepared in Example 5 above Example 1 using the same material and the die and, applying pressure to the material B 2.1 kg / cm ^2, the material A 1.8kg / cm ^2. At this time, the thickness of the foam layer was 42 μm for the inner foam layer and 8 μm for the outer foam layer.

(Example 6) An inner layer was prepared by adding 3 parts by weight of a thermal decomposition type foaming agent (Wako Pure Chemical Industries, Ltd.) to 100 parts by weight of a fluorine acrylate-based UV-crosslinking resin (Dainippon Ink and Chemicals), and an outer layer. A urethane acrylate-based UV-crosslinking resin (electrochemical) was used for the above.

The first die pressure was 2.1 kg / cm ² and the second die pressure was 1.8 kg / cm ² , and the die diameters were φ0.14 mm and φ0.16 mm, respectively. A 42 AWG stranded wire (7 / 0.025) was used as a conductor, the linear velocity at this time was 90 m / min, and the foam was passed through an electric furnace having a total length of 80 cm and a temperature of 400 ° C.

The ultraviolet lamp used for the pre-cure was a metal halide lamp using a glass filter to cut off wavelength components of 300 nm or more and irradiate only short wavelength components. Irradiation was performed with a metal halide lamp without using a filter during post cure.

The outer diameter of the electric wire manufactured under the above conditions is 195
The thickness of the inner layer was 50 μm, and the thickness of the outer layer was 10 μm.

(Comparative Example 1) 42 A obtained by adding 5 parts by weight of a thermal decomposition type foaming agent to the ultraviolet cross-linking resin used in Example 1
It was coated on a WG (7 / 0.025) conductor with a die of φ0.16 mm at a pressure of 1.8 kg / cm ² , and foamed and cured in the same manner as in Example 1.

(Comparative Example 2) 42 A of the ultraviolet-crosslinking resin used in Example 1 to which 3 parts by weight of a thermal decomposition type foaming agent was added
It was coated on a WG (7 / 0.025) conductor with a die of φ0.16 mm at a pressure of 1.8 kg / cm ² , and foamed and cured in the same manner as in Example 1.

(Manufacturing Method) The basic manufacturing method is to apply a resin composition to the outer periphery of the conductor and irradiate it with ultraviolet rays.

FIG. 3 shows a cross-sectional view of a continuous coating die used in the method for producing an ultraviolet crosslinked foam insulated wire according to the present invention, wherein 5 is a conductor, 6 is a paint tank for inner layer coating, and 7 is a coating tank.
Is an inner layer coating die, 8 is an outer layer coating paint tank, 9 is an outer layer coating die, and 10 is a coating device.

FIG. 4 is a flow sheet explanatory view showing an embodiment of the method for producing an ultraviolet crosslinked foam insulated wire according to the present invention. 5 is a conductor, 10 is a coating device, 11 is an ultraviolet precure irradiation lamp, and 12 is. The electric furnace 13 is an ultraviolet post-cure irradiation lamp.

This coating apparatus 10 makes it possible to continuously coat the inner layer and the outer layer at different pressures. When it is desired to obtain ultra-high foaming, it is possible to preheat the conductor before applying this coating. It is desirable to use compressed nitrogen as the pressure source, which does not have the adverse effect of oxygen, but it is not particularly limited. In these examples, two types of continuous coating are used, but two or more types may be used.

After coating, the process of ultraviolet irradiation and foaming is started. Although this combination can be arbitrarily set according to the properties of the electric wire to be manufactured, the step shown in FIG. 4 in which pre-curing of pre-irradiation with an ultraviolet lamp also serving as liquid sagging prevention is preferable after passing through the die.

The heating method in the foaming step is not particularly limited.
Although a method using an electric furnace is generally used, it is desirable to use high frequency conductor heating together in order to give priority to foaming of the inner layer.

For the purpose of curing the insulating layer, it is desirable that the irradiation of ultraviolet rays after foaming, so-called post-cure, be strong.
In addition, by limiting the irradiation wavelength with a filter, including during pre-cure, or by changing the structure of the irradiation device,
It is also possible to adjust the degree of crosslinking by changing the irradiation dose to the inner layer and the outer layer.

(Evaluation Method) (1) Electric Wire to be Tested UV-Crosslinked Foam Insulated Electric Wire According to Examples 1-6 UV-Crosslinked Foam Insulated Electric Wire According to Comparative Examples 1-2 (2) Evaluation Method Gel Fraction: 110 ° C. in xylene 24 hours extraction

[0056]

[Equation 1]

Foaming degree: Void area occupied in the cross-sectional area Appearance: Visual inspection with a microscope (Production conditions and evaluation test results of the obtained insulated wire) Manufacturing conditions of Examples and Comparative Examples and obtained insulated wires The evaluation test results are summarized in Table 1.

[0058]

[Table 1]

As can be seen from Table 1, the ultraviolet-crosslinked foamed insulated electric wire of Comparative Example 1 had a gel fraction as low as 65%, and therefore had the lowest degree of crosslinking, and also had a poor appearance.

The UV-crosslinked foamed insulated electric wire of Comparative Example 1 also had the gel fraction of 75%, which was the second lowest, and therefore the degree of crosslinking was low and the degree of foaming was also the lowest of 35%.

On the other hand, the gel fractions of the UV-crosslinked foamed insulated electric wires of Examples 1 to 6 were all high at 90% or more,
Therefore, the degree of crosslinking is remarkably high. Further, the degree of foaming can be arbitrarily produced, and the appearance is good. These can significantly reduce the amount of the foaming agent added to the UV-crosslinked foamed insulating insulation layer and the amount of radicals generated at the time of foaming, and as a result effectively suppress the reduction of the crosslink density and cause excessive irradiation of ionizing radiation. It is possible to obtain an ultraviolet-crosslinked foam insulated electric wire in which the harmful effects are completely eliminated.

[0062]

EFFECT OF THE INVENTION According to the ultraviolet-crosslinked foamed insulated electric wire of the present invention and the method for producing the same, the ultraviolet-crosslinked foamed insulated electric wire can have a remarkably high degree of crosslinking and can be produced with an arbitrary degree of foaming, and has a good appearance. , These can significantly reduce the addition amount of the foaming agent added to the UV-crosslinked foamed insulating layer and the radical generation amount generated at the time of foaming, and as a result effectively suppress the reduction of the crosslink density and cause excessive irradiation of ionizing radiation. It is possible to obtain an ultraviolet-crosslinked foam insulated electric wire in which the harmful effects are completely eliminated, and is industrially useful.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of an ultraviolet cross-linked foam insulated electric wire according to Example 1 of the present invention.

FIG. 2 is a cross-sectional explanatory view of an ultraviolet cross-linked foam insulated electric wire according to Example 4 of the present invention.

FIG. 3 is a cross-sectional view of a coating apparatus used in the method for producing an ultraviolet-crosslinked foamed insulated wire of the present invention.

FIG. 4 is a flow sheet explanatory view showing an example of a method for producing an ultraviolet-crosslinked foamed insulated wire of the present invention.

[Explanation of symbols]

1 conductor 2 UV-crosslinking foam insulation layer of inner layer 3 UV-crosslinking foam insulation layer of outer layer 4 UV cross-linking insulation layer of outer layer 5 Conductor 6 Paint tank for inner layer coating 7 Inner layer coating die 8 Paint tank for outer layer coating 9 Outer layer coating die 10 coating equipment 11 UV pre-cure irradiation lamp 12 Electric furnace 13 UV post-cure irradiation lamp

Claims (10)

[Claims] 1. An ultraviolet-crosslinked foamed insulated wire comprising a conductor and an ultraviolet-crosslinked foamed insulation layer provided on the conductor, wherein the ultraviolet-crosslinked foamed insulation layer is composed of a plurality of divided layers having different foaming degrees. Foam insulated wire. 2. The ultraviolet cross-linked foam insulated electric wire according to claim 1, wherein the degree of foaming of the ultraviolet cross-linked foam insulating layer is changed stepwise. 3. The ultraviolet cross-linking foamed insulating layer is constructed so that the foaming degree changes stepwise so that the conductor side has a high foaming degree and the outer layer side has a low foaming degree.
The ultraviolet-crosslinked foam insulated electric wire described. 4. The ultraviolet-crosslinked foamed insulated wire according to claim 1, wherein the ultraviolet-crosslinked foamed insulation layer contains an ultraviolet-crosslinking resin and a pyrolysis foaming foaming agent. 5. An ultraviolet-crosslinking foam insulating layer composed of a plurality of divided layers having different degrees of foaming is provided on the conductor, and an ultraviolet-crosslinking resin layer is provided on the ultraviolet-crosslinking foam insulating layer. UV cross-linked foam insulated wire. 6. The ultraviolet-crosslinked foamed insulated wire according to claim 5, wherein the ultraviolet-crosslinked foamed insulation layer contains an ultraviolet-crosslinking resin and a pyrolysis foaming foaming agent. 7. A continuous coating of two or more kinds of ultraviolet cross-linking resin paint containing an ultraviolet cross-linking resin and a pyrolytic foaming agent,
A method for producing an ultraviolet-crosslinked foamed insulated wire, which comprises irradiating ultraviolet rays and then heating and foaming. 8. A continuous coating of two or more kinds of ultraviolet cross-linking resin paint containing an ultraviolet cross-linking resin and a pyrolysis foaming foaming agent,
Apply an ultraviolet cross-linking resin paint on the upper layer, and after that, pre-irradiate with ultraviolet rays and then heat, then irradiate with ultraviolet rays,
Finally, a method for producing an ultraviolet-crosslinked foamed insulated wire, which comprises heat-foaming. 9. The method for producing an ultraviolet-crosslinked foam insulated wire according to claim 7, wherein a preheated ultraviolet-crosslinking resin coating material is applied onto the conductor. 10. The method for producing an ultraviolet-crosslinked foam insulated wire according to claim 7, wherein ultraviolet rays having a specific wavelength are selectively irradiated by a filter or an ultraviolet irradiation lamp.