JPS5913125B2 - Manufacturing method of enameled electric wire - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel method for manufacturing enamelled electric wire.

More specifically, the present invention relates to a method for producing an enameled electric wire that has a good appearance and excellent coating properties, particularly wear resistance and heat softening resistance, without using organic solvents.
Traditionally, enameled electric wires have been produced by dissolving acrylic resins, polyester resins, polyester imide resins, polyester amide imide resins, etc. in organic solvents, and using resins with a solid content of about 20 to 60% (wt%, the same applies hereinafter). The most common method of producing enamelled wires is to apply a resin solution of about 100% to a copper wire several times and then apply a baking treatment to it. A method is used to manufacture enameled electric wire by coating and heating the coated wire.

However, in the former method, the large amount of organic solvent used is extremely harmful to the human body.10 During the baking process, this harmful organic solvent scatters, which is a big problem in terms of health and safety, and also causes large losses due to scattering. , it is also economically inferior.

In addition, in the case of the latter method, simply heating the electrodeposited film made by electrodepositing aqueous dispersion varnish on copper wire will not produce enough heat.
Since cracks and cracks occur, making it difficult to form a continuous film, treatment is performed using an organic solvent or its vapor before heating in order to form a continuous film. Inferior. Furthermore, since an aqueous dispersion varnish is used, the film properties, particularly abrasion resistance and heat softening resistance, are poor. However, as a result of various studies aimed at eliminating these drawbacks, the present inventors found that after electrodepositing an acrylic water-based dispersion varnish on a copper wire, this was further coated with a water-soluble polyester resin solution or a water-soluble polyester imide resin. When manufacturing enamelled wires by immersing them in a solution and then heating and hardening them,
A continuous coating that is excellent in terms of safety and hygiene and has a good appearance can be easily formed without using harmful organic solvents, and the formed coating has wear resistance,
The present invention was completed based on the discovery that it has remarkable effects, such as excellent heat softening resistance, which could never be achieved by conventional methods.

That is, in the present invention, an acrylic aqueous dispersion x varnish is electrodeposited on a copper wire, and then it is immersed in a water-soluble polyester resin solution or a water-soluble polyesterimide resin solution, and then heated and cured to remove harmful organic solvents. The present invention relates to a method for producing an enameled electric wire that has a good appearance without blisters, cracks, pinholes, etc., and has excellent coating properties, particularly abrasion resistance and heat softening resistance, without using enamel. Typical acrylic aqueous dispersion varnishes used in the present invention include, for example, an aqueous copolymer dispersion of acrylonitrile, styrene, glycidyl methacrylate and methacrylic acid, and a copolymer of acrylonitrile, methyl methacrylate, glycidyl methacrylate and methacrylic acid. Aqueous dispersions, aqueous dispersions of copolymers of acrylonitrile, ethyl acrylate, glycidyl methacrylate and methacrylic acid, aqueous dispersions of copolymers of acrylonitrile, vinyl acetate and methacrylic acid, acrylonitrile, styrene, ethyl acrylate, N-methylolacrylamide and methacrylic Examples include aqueous acid copolymer dispersions, but are not limited to these.

These acrylic aqueous dispersion varnishes can be obtained by emulsion copolymerizing the above varnish components using an emulsifier and a polymerization initiator in a conventional manner. Aqueous dispersion varnishes are preferred, and further contain at least one emulsifier.
Acrylic aqueous dispersion varnishes obtained by using more than one type of anionic surfactant have extremely excellent electrodepositivity and are very suitably used. The water-soluble polyester resin solution and water-soluble polyesterimide resin solution for dipping treatment used in the present invention can be suitably used regardless of the composition components, but immediately preferred representative examples include polyethylene terephthalate and polyethylene terephthalate. A polyethylene tyrephthalate water-soluble polyester resin solution prepared by reacting a polyester resin consisting of tris-(2-hydroxyethyl) isocyanurate with trimellitic anhydride and dissolving it in ammonia-containing water, or a polyester resin solution containing trimellitic anhydride or diamino Examples include a water-soluble polyesterimide resin solution prepared by reacting a polyesterimide resin consisting of a diamine such as diphenylmethane, polyethylene terephmolelate, and glycerin with trimellitic anhydride and dissolving it in ammonia-containing water.

These water-soluble resin solutions have the effect of promoting film formation and further improving film properties, particularly abrasion resistance and heat softening resistance.

Furthermore, m-cresol, dimethylformamide, etc. are added to these water-soluble resin solutions in an amount of 5% based on the resin solid content in the solution.
Those blended at a ratio of about 30% have the advantage of improving continuous film formation and are not so harmful to the human body, so they can be suitably used. Note that these water-soluble resin solutions usually have a resin solid content of 10 to 2
Although it is preferable to use it as a solution of about 0%, even if it is a highly viscous water-soluble resin solution containing 20% or more of resin solids, it is possible to adjust the viscosity by performing operations such as heating. can be used. When carrying out the method of the present invention, the acrylic aqueous dispersion varnish is electrodeposited on a copper wire, for example, with an electrodeposited film thickness of usually about 20 to 30 μm for one diameter copper wire. It is appropriate to
There are no particular restrictions on immersing this in the water-soluble polyester resin solution or water-soluble polyesterimide resin solution as long as the immersion is done to the extent that no sagging or sagging occurs.

Further, the curing temperature, curing time, etc. when heating and curing after the dipping treatment may be appropriately determined depending on the type of the acrylic aqueous dispersion varnish or the water-soluble resin solution. As mentioned above, when producing enameled electric wires by the method of the present invention, it is extremely superior in terms of safety and hygiene, is economical, and has good appearance and film properties, especially without using organic solvents that are harmful to the human body. Enameled wires with excellent abrasion resistance and heat softening resistance can be obtained, which is extremely advantageous industrially. Next, the method of the present invention will be explained with reference to Examples.

Example 1 - 5 Five types of acrylic aqueous dispersion varnishes prepared by emulsion polymerization in the proportions of the ingredients shown in Table 1 were electrodeposited onto copper wires having a diameter of 1 to 51 U so that the electrodeposited film thickness was approximately 25 μm. However, these water-soluble polyester resin solutions (polyester resins consisting of polyethylene terephthalate and tris-(2-hydroxyethyl) isocyanurate are reacted with trimellitic anhydride) are dissolved in water containing ammonia. , solid resin content 1
2 (:fl)) or a water-soluble polyesterimide resin solution (a polyesterimide resin consisting of trimellitic anhydride, diaminodiphenylmethane, polyethylene terephthalate, and glycerin reacted with trimellitic anhydride) in water containing ammonia. (15% solid resin content) or m
- A water-soluble polyesterimide resin solution containing cresol (the water-soluble polyesterimide resin solution was dissolved in m-cresol at a concentration of 30% based on the solid content of the resin in the solution, and the solution was further dissolved in aqueous ammonia). The wires were immersed in the prepared resin solution) and then heated and cured under the curing conditions shown in Table 1 to obtain five types of enameled electric wires.

Table 2 shows the results of measuring the thermal softening temperature and other wire characteristics of the five types of enameled wires obtained. The presence or absence of pinholes was determined by visually observing the five types of enameled wires obtained by applying approximately 12 DC voltages in saline water, and the wear resistance was determined by the number of reciprocating cycles until the coating wore off due to reciprocating abrasion. It was shown in

Example 6 The acrylic aqueous dispersion varnish used in Example 1 was 11!
The electrodeposited film was electrodeposited on a thick diameter copper wire to a thickness of about 25 μm, and the electrodeposited film was immersed in the water-soluble polyesterimide resin solution containing m-cresol used in Example 5, and then heated at 100°C for 10 minutes.
The enameled electric wire was cured by heating at 240° C. for 1 hour.

Table 2 also shows the results of measuring the thermal softening temperature and other wire characteristics of the obtained enameled wire. The presence or absence of pinholes and the wear resistance were measured in the same manner as in Examples 1 to 5.

Claims (1)

[Claims] 1 After electrodepositing acrylic water-based dispersion varnish on copper wire,
A method for producing an enameled electric wire, which comprises immersing the wire in a water-soluble polyester resin solution or a water-soluble polyesterimide resin solution, and then heating and curing the wire.