JPH07335053A - Method for manufacturing porous insulated wire - Google Patents

Abstract

(57) [Summary] [Object] To provide a method capable of easily and rapidly producing a porous (foamed) insulated electric wire having a good appearance. [Structure] The element wire (conductor) 1 sent from the sending machine 4 is
An ultraviolet-crosslinking resin composition for porosity (an ultraviolet-crosslinking material to which a soluble compound is added; hereinafter referred to as an insulating material) is applied in a coating tank 5, and then the strand 1 is applied in an ultraviolet irradiation furnace 6. The insulating material applied to the substrate is irradiated with ultraviolet rays to be cured, and then the coated and cured conductor with an insulating material 1 is passed through the hot water elution tank 7 to remove the soluble compound contained therein. Then, the porous insulated electric wire is wound up through the drying furnace 8 and the winding machine 9.

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 a porous insulated electric wire (foam insulated electric wire).

[0002]

2. Description of the Related Art In recent years, communication equipment and precision electronic equipment have been remarkably reduced in size or mounted in high density, and in order to meet the demand, the cable core wire is also tending to be further reduced in diameter. , Insulated electric wires with an outer diameter of 0.5 mm or less have also been used.

On the other hand, in computers and the like, there is a marked tendency to demand even higher speeds of transmission signals, and the insulation layer of the above-mentioned thin 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 increase the speed of transmission signals by increasing the permittivity.

As a method of coating a signal transmission wire (cable) of a computer or the like with a foamed insulation (porous insulation), a method of winding a film which has been foamed in advance on a conductor is known. Extrusion is often used to form the coating. As a foaming means for such an insulator, a physical gas foaming method of foaming with a gas and a chemical foaming method utilizing a chemical reaction are known.

In the former gas foaming method, a volatile foaming liquid such as liquid freon is forcibly injected into a molten resin, and foaming is performed by its vaporizing pressure, or bubbles are directly formed in the molten resin in an extruder. There is a method in which a cell-shaped fine closed cell body uniformly distributed is generated in a resin by pressurizing a working gas.

The latter chemical foaming method is a method in which a foaming agent is molded in a state of being dispersed and mixed in a resin, and then heat is applied to chemically and chemically decompose the foaming agent to generate gas and foam. is there.

[0007]

The former method of gas foaming described above is one in which the resin is once melted and the volatile foaming liquid is forcedly injected into it, which may require a strong pressure. Many. Further, such a liquefied gas has a strong vaporization pressure, and it is difficult to obtain a fine foam structure, and it is also difficult to obtain a good product appearance. Further, since the injection speed of the liquefied gas is slow, it is difficult to increase the speed, and there is a problem that productivity is poor.

In addition, the method of directly injecting gas in the extruder requires special equipment and technology in terms of safety.

On the other hand, in the case of chemical foaming, it is necessary to previously knead and disperse the foaming agent into the resin as described above, and the gas generated by the reaction decomposition of this foaming agent by heat after molding is performed. Is used for foaming. Therefore, there is a problem that the molding temperature of the resin at this time must be kept lower than the decomposition temperature of the foaming agent in order to prevent the foaming agent from decomposing during the molding processing. There is a problem of being significantly restricted.

Further, in the case of the extrusion coating method, there is another problem that if the diameter of the wire becomes thin, pressure is likely to cause wire breakage, which makes speeding up difficult. There is also a problem that it is difficult to respond to specific requests.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method capable of easily and rapidly producing a porous (foamed) insulated electric wire having a good appearance.

[0012]

The gist of the first invention is to coat a conductor with an ultraviolet-crosslinking resin composition for porosity, which is formed by adding a soluble compound to an ultraviolet-crosslinking material, and after curing with an ultraviolet ray, This is to elute the soluble compound to obtain an electric wire of porous insulation (foam insulation).

The gist of the second invention is to form a film from an ultraviolet-crosslinking resin composition for porosity, which is formed by adding a soluble compound to an ultraviolet-crosslinking material, and irradiate the film with ultraviolet rays to cure it, That is, the soluble compound is eluted to form a porous insulating film, and the porous insulating film is wound around a conductor to obtain a porous insulating electric wire.

Specific examples of the constituent elements of the present invention will now be described.

(1) UV-Crosslinking Material The UV-crosslinking material used in the present invention basically comprises a photopolymerizable oligomer, a photopolymerizable monomer, a photopolymerization initiator and the like.

The photopolymerizable oligomer (prepolymer) is, 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. Various oligomers such as acrylate type, silicone acrylate type, polybutadiene acrylate type, polystyrene ethyl methacrylate type, polycarbonate dicarbonate type, unsaturated polyester type, polyene / thiol type, and functional groups having unsaturated double bonds, such as acryloyl group. , Having at least two methacryloyl groups, allyl groups and vinyl groups. The oligomer may be fluorine-substituted, or 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, vinyl group and allyl 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 UV crosslinking, and the photopolymerization initiator is a substance that easily absorbs a specific wavelength upon irradiation with UV to be in an electronically excited state to generate a radical. For example, benzoin ether type, ketal type, acetophenone type,
There are benzophenone type, thioxanthone type, etc., and various photopolymerization initiators can be used according to the purpose.

The dielectric constant of the resin composition containing no soluble compound is 5 or less, preferably 4 or less.

(2) Soluble Compound The soluble compound may be any compound that can be eluted from a molded body that has been cured by ultraviolet light by immersing an arbitrary solution. As the compound, an organic compound is suitable from the viewpoint of handleability and safety such as treatment of liquid after elution. In particular, water-soluble organic compounds are most preferable.

As the water-soluble organic compound, highly soluble organic compounds such as acetamide, sodium benzoate, antipyrine, methyl carbamate, potassium formate, potassium acetate, phthalic acid, maleic acid, malonic acid, sucrose and urea can be used. can give. Solubility is 50g at 20 ℃
/ 100cc or more is preferable. Therefore, if the solubility is low, there is a problem that elution takes time and productivity is deteriorated.

In the present invention, a skin layer having a thickness of 10 μm or less may be provided by using the ultraviolet cross-linking resin composition.
This is effective in improving the mechanical strength of the porous material, reducing the deformation due to external pressure, and achieving a smooth appearance. The reason why the skin layer is set to 10 μm or less is that, in a thin and thin foam insulated wire, a thick skin layer causes a problem of increasing the propagation delay time. Preferably, the ratio of the skin layer to the porous layer (insulating coating) is 1/20 to 1/5. If it is smaller than 1/20, it is difficult to obtain the reinforcing effect as the skin layer, and if it is larger than 1/5, there is a problem that the propagation delay time is increased.

[0023]

According to such a manufacturing method, in the first invention, for example, a porosifying ultraviolet resin composition (insulating coating material) is used.
After being applied to the conductor, it is cured through an ultraviolet irradiation furnace, then the soluble compound is eluted from the above insulation coating material through a warm water elution tank, and finally through a drying oven, an electric wire with a porous insulation coating is obtained. To be

In the second invention, the film to be a porous insulator is cured by ultraviolet irradiation of the ultraviolet-crosslinking resin composition for porosity (for example, ultraviolet irradiation in a nitrogen atmosphere), as in the first invention. It is obtained through the subsequent elution step of the soluble compound by elution with warm water.

Therefore, the problems of the conventional physical gas foaming method (the point of forced injection of the volatile foaming liquid into the molten resin, the difficulty of obtaining a fine foam structure due to the liquefied gas, the production It does not cause problems such as difficulty in speeding up or problems with extrusion) and problems with the chemical foaming method (the problem of keeping the resin molding processing temperature below the decomposition temperature of the foaming agent so that the foaming agent does not decompose during molding processing). Thus, a good porous insulated wire can be obtained.

[0026]

EXAMPLES Examples of the present invention will be described below. The porosity in each of the following examples is a numerical value calculated by the following formula.

[0027]

[Equation 1]

Here, A is a coating material obtained by curing a resin composition containing no soluble compound, and B is a coating material obtained by curing a resin composition containing a soluble compound.

Examples 1 to 3 are manufacturing methods according to the first invention, and Example 4 is a manufacturing method according to the second invention.

Example 1 100 parts by weight of urethane acrylate oligomer U-122A (manufactured by Shin-Nakamura Chemical) and 50 parts by weight of dicyclopentanyl acrylate (manufactured by Hitachi Chemical).
Photoinitiator 2,2-dimethoxy-2-phenylacetophenone 7.5 parts by weight, sucrose (specific gravity 1.588) 200
After coating a wire conductor 0.31 (7 / 0.102) of tin-plated annealed copper with a UV-crosslinking resin composition for porosity consisting of parts by weight, it is cured through an UV irradiation furnace, and the insulation thickness is passed through a warm water elution tank and a drying furnace. I got an insulated wire of 50 μm,
When the porosity was measured, a 50 ± 5% porous insulated electric wire (foamed insulated electric wire) was obtained.

Example 2 100 parts by weight of urethane acrylate oligomer U-122A, 50 parts by weight of dicyclopentanyl methacrylate, 7.5 parts by weight of photoinitiator 2,2-dimethoxy-2-phenylacetophenone, and 4 parts of sucrose.
After coating 0.31 (7 / 0.102) of tin-plated annealed copper wire conductor with an ultraviolet-crosslinking resin composition for porosity consisting of 100 parts by weight, it is cured through an ultraviolet irradiation furnace and insulated through a hot water elution tank and a drying furnace. When an insulated electric wire having a thickness of 50 μm was obtained and the porosity was measured, a 65 ± 5% porous insulated electric wire was obtained.

Example 3 100 parts by weight of urethane acrylate oligomer U-122A, 50 parts by weight of dicyclopentanyl methacrylate, 7.5 parts by weight of 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator, and urea (specific gravity: 1 .323) 165 parts by weight of the ultraviolet-crosslinking resin composition for porosity was applied to a tin conductor annealed copper stranded wire conductor 0.31 (7
/0.102) and then cured through an ultraviolet irradiation oven, and an insulation thickness of 50 through a hot water elution bath and a drying oven.
When we obtained an insulated wire of μm and measured the porosity,
A 5% porous insulated electric wire was obtained.

FIG. 1 shows an example of a manufacturing line used in each of the above-mentioned embodiments.

In FIG. 1, the strand (conductor) 1 sent out from the feeder 4 is coated with the ultraviolet crosslinkable resin composition for porosity in the coating tank 5, and then the strand is placed in the ultraviolet irradiation furnace 6 as described above. The ultraviolet-crosslinking resin composition for porosification applied to No. 1 is irradiated with ultraviolet rays to be cured, and then the coated and cured conductor 1 with the ultraviolet-crosslinking resin composition for porosity is passed through the hot water elution tank 7 and contained therein. Soluble compounds are removed.
Then, the porous insulated electric wire is wound up through the drying furnace 8 and the winding machine 9.

Sectional structures of various porous insulated electric wires obtained by the above examples are shown in FIGS.

The porous insulated wire of FIGS. 2 (a) and 2 (b) comprises a conductor 1 and a porous insulator (coating material) 2 obtained by the production of the present invention, and FIG. 2 (c) shows the conductor 1 described above. In addition to the porous insulator 2, a skin layer 3 is provided on the outer periphery of the porous insulator 2.

(Example 4) 100 parts by weight of urethane acrylate oligomer U-122A, 50 parts by weight of dicyclopentanyl methacrylate, 7.5 parts by weight of 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator, and sucrose 2
A UV-crosslinking resin composition for porosity comprising 100 parts by weight,
Pour on a glass plate, use a 3 MIL (75 μm) doctor blade to form a film, cure it by passing ultraviolet light in a nitrogen atmosphere, immerse it in a warm water elution tank, and then dry it to measure the porosity of the film. When done, 50 ± 5%
A porous UV crosslinked film of was obtained. Then, this film was wound around a conductor to obtain a porous insulated electric wire.

[0038]

As described above, according to the present invention, the ultraviolet-crosslinking resin composition for porosity, which serves as a coating material, is cured by ultraviolet rays, and the soluble compound contained therein can be easily prepared. By eluting it to make it porous, it is possible to easily and rapidly obtain a porous insulated electric wire having an excellent foaming degree and an excellent appearance.

Further, in the first invention, since the liquid resin composition is applied to the conductor, it is easy to manufacture a thin-walled foamed thin insulated wire, and it is possible to meet today's demands.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a production line for carrying out the production method of the present invention.

FIG. 2 is a cross-sectional view showing various aspects of a porous insulated wire obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1 Elementary Wire (Conductor) 2 Porous Insulator 3 Skin Layer 4 Feeder 5 Coating Tank 6 Ultraviolet Irradiation Furnace 7 Elution Tank 8 Drying Furnace 9 Winder

Claims (4)

[Claims] 1. A porous cross-linking resin composition obtained by adding a soluble compound to an ultraviolet cross-linking material is applied to a conductor and cured with ultraviolet rays, and then the soluble compound is eluted to elute the porous insulating material. A method for producing a porous insulated electric wire, which comprises obtaining an electric wire. 2. A film is formed from an ultraviolet-crosslinking resin composition for porosity, which is formed by adding a soluble compound to an ultraviolet-crosslinking material, and the film is irradiated with ultraviolet rays to be cured, and then the soluble compound is eluted. A method for producing a porous insulated electric wire, characterized in that a porous insulating film is produced by winding the porous insulating film around a conductor to obtain a porous insulated electric wire. 3. The method for producing a porous insulated wire according to claim 1 or 2, wherein the soluble compound is an organic compound. 4. The method for producing a porous insulated wire according to any one of claims 1 to 3, wherein the soluble compound is water-soluble.