JP2003016846A - Enameled wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an enameled wire of low water-absorption coefficient, causing no corrosion of the conductor, and having an dielectric characteristics. SOLUTION: This enameled wire is provided by coating the conductor with a vanish, prepared by dissolving 0.5-100 pts.wt. of aromatic liquid crystal polyester resin to 100 pts.wt. of a solvent containing 30 wt.% or more of a phenol compound expressed by general formula (I). In the formula, A is a halogen atom or a tri-halogenated methyl group; and i is an integer of 1-5. When i is 2 or more, the plurality of As may be same or different.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an enameled wire obtained by coating a conductive wire with a varnish of an aromatic liquid crystal polyester resin.

[0002]

2. Description of the Related Art In recent years, enameled wires used in electronic and electric devices are required to be compatible with high frequencies and have a low water absorption. However, polyester resins, polyurethane resins, polyimide resins, and polyamide-imide resins, which have been conventionally used as coatings for enameled wires, have a problem that they have a high water absorption rate and a large dielectric constant or dielectric loss in a high frequency band. . Therefore, the use of an aromatic liquid crystal polyester resin having a low water absorption rate for enamel wire applications has been studied. For example, JP-A-62-64832
The publication discloses a solution obtained by dissolving an aromatic liquid crystal polyester resin in trifluoroacetic acid. However, when the solution is used for coating a conductive wire, there are problems such as corrosion of the conductive wire and also safety and health problems.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an enameled wire which has a low water absorption rate, does not corrode the conductive wire, and has excellent dielectric properties.

[0004]

Means for Solving the Problems As a result of intensive studies to find an enameled wire free from the above problems, the present inventors have found that an aromatic liquid crystal compound in a solvent containing 30% by weight or more of a specific phenol compound. The inventors have found that an enamel wire obtained by coating a conducting wire with a varnish obtained by dissolving a polyester resin has a low water absorption rate and excellent dielectric properties, and completed the present invention.

That is, the present invention provides a solvent 1 containing 30% by weight or more of a phenol compound represented by the following general formula (I).
Aromatic liquid crystal polyester resin 0.
The present invention provides an enamel wire comprising a conductive wire coated with a varnish obtained by melting 5 to 100 parts by weight. (I) (In the formula, A represents a halogen atom or a trihalogenated methyl group, and i represents an integer of 1 or more and 5 or less. When i is 2 or more, plural A's may be the same or different. It may be.)

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The aromatic liquid crystal polyester resin used in the present invention is a polyester resin classified into thermotropic liquid crystalline polymer. For example, from (1) a combination of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol, , (2) different aromatic hydroxycarboxylic acids, (3) combinations of aromatic dicarboxylic acids and aromatic diols, (4) polyesters such as polyethylene terephthalate with aromatic hydroxycarboxylic acids. What was reacted,
Etc., and forms an anisotropic melt at a temperature of 400 ° C. or lower. Instead of these aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids and aromatic diols, those ester forming derivatives may be used.

Examples of the ester-forming derivative of carboxylic acid include those in which a carboxyl group is a derivative having a high reaction activity for acid chlorides, acid anhydrides and the like and accelerating the reaction to form polyester, carboxyl. Examples thereof include those in which the group forms an ester with alcohols, ethylene glycol, and the like, and is a derivative that produces a polyester by a transesterification reaction. Examples of the ester-forming derivative of the phenolic hydroxyl group include those in which the phenolic hydroxyl group forms an ester with a carboxylic acid and forms a polyester by a transesterification reaction. Also, aromatic hydroxycarboxylic acid,
The aromatic dicarboxylic acid and aromatic diol may be substituted with an alkyl group such as a methyl group or an ethyl group, a halogen atom, an aryl group, or the like, as long as the ester-forming property is not impaired.

Examples of the repeating unit of the liquid crystal polyester include the followings, but the present invention is not limited thereto. Repeating structural unit derived from aromatic hydroxycarboxylic acid: (The above repeating structural unit may be substituted with a halogen atom or an alkyl group.)

Repeating structural unit derived from aromatic dicarboxylic acid: (The above-mentioned repeating structural unit may be substituted with a halogen atom, an alkyl group or an aryl group.)

Repeating structural units derived from aromatic diols: (The above repeating structural unit may be substituted with a halogen atom, an alkyl group or an aryl group.) In the above repeating structural unit, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and aryl. As the group, an aryl group having 6 to 20 carbon atoms is preferable.

From the balance of heat resistance and mechanical properties, the aromatic liquid crystal polyester preferably contains at least 30 mol% of the repeating structural unit represented by the above formula A ₁ . Specifically, the combination of repeating structural units is represented by the following formula (a):
Those of (f) are preferred. (A): (A ₁ ), (B ₂ ), (C ₃ ), or
In (A ₁ ), a mixture of (B ₁ ) and (B ₂ ), and a combination of structural units of (C ₃ ) (b) :( a), some or all of (C ₃ ) may be replaced with (C ₁ ) derived by replacing (c) in those combinations of the structural units of :( a), the structural units of (C ₃₎ those obtained by replacing a part or all the _{(C 2) (d) :(} a) in combination with those, the ones of the combination of structural units of (C ₃₎ those obtained by replacing a part or all the _{(C 4) (e) :(} a), a part or all of (C ₃₎ ( C ₄₎ and (in C ₅₎ replaced with the mixture of (f) as a combination of the structural units of :( a), obtained by replacing a part of (a ₁₎ to (a _2).

Further, as the aromatic polyester used in the present invention, from the viewpoint of exhibiting liquid crystallinity, 30 to 80 mol% of repeating structural units derived from p-hydroxybenzoic acid, hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 10 to 35 mol% of repeating structural units derived from at least one compound selected from the group consisting of bisphenol A and bisphenol S, and derived from at least one compound selected from the group consisting of terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid It is preferably composed of repeating structural units of 10 to 35 mol%.

The solvent used in the present invention contains 30% by weight or more of the phenol compound represented by the above general formula (I). When the solvent is used, the aromatic liquid crystal polyester can be dissolved at room temperature or under heating. Since the aromatic liquid crystal polyester can be dissolved at a relatively low temperature, it is preferable that these phenol compounds are contained in an amount of 60% by weight or more.

In the general formula (I), A represents a halogen atom or a trihalogenated methyl group. i represents an integer of 1 or more and 5 or less. When i is 2 or more, plural A's may be the same or different, but are preferably the same. Here, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoint of solubility, a fluorine atom and a chlorine atom are preferable, and a chlorine atom is more preferable from the viewpoint of the balance between cost and solubility. preferable. Among these, a phenol compound in which a halogen atom is a chlorine atom is preferable from the viewpoint of price and availability, o-chlorophenol and p-chlorophenol are more preferable, and p-chlorophenol is further preferable from the viewpoint of solubility. .

The varnish used in the present invention has an aromatic liquid crystal polyester resin of 0.5 to 10 relative to 100 parts by weight of the solvent.
It is obtained by dissolving 0 parts by weight, preferably 1 to 70 parts by weight, more preferably 2 to 50 parts by weight. If the amount of the aromatic liquid crystal polyester resin is less than 0.5 parts by weight, the effective concentration is low and not practical, and if it exceeds 100 parts by weight, the viscosity and thixotropy of the varnish are increased and the handling becomes difficult.

Further, in the present invention, a thermoplastic resin, a thermosetting resin or the like can be added to the varnish within a range that does not impair the characteristics of the aromatic liquid crystal polyester resin. Examples of the thermoplastic resin include polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenyl ether and modified products thereof, polyetherimide, polyamideimide and modified products thereof. Examples of the thermosetting resin include phenol resin, epoxy resin, polyimide resin, cyanate resin and the like.

Further, the varnish may be blended with a pigment, a leveling agent, etc. within a range not impairing the object of the present invention. Examples of the pigment include color pigments such as titanium dioxide and carbon black; extender pigments such as talc, silica, alumina and barium sulfate. Examples of the leveling agent include a fluorine-based leveling agent and a silicone-based leveling agent.

The enamel wire of the present invention can be manufactured by applying a varnish on a conductor and baking it to form a coating layer. The material of the conducting wire is not particularly limited, but examples thereof include copper and aluminum. The baking temperature is usually 100 ° C to 500 ° C. As the coating layer, a single layer made of an aromatic liquid crystal polyester resin may be used, or a plurality of layers may be used in combination with other insulating layers. Examples of the case of using as a multi-layer include a case where an aromatic liquid crystal polyester resin varnish is directly coated on a conductor, and a case where a conductor already coated with another resin is overcoated with an aromatic liquid crystal polyester resin varnish. When the coating layer is formed as a multiple layer, polyurethane, polyester, polyester imide, polyester amide imide, polyamide imide, polyimide, nylon and the like can be used in addition to the present aromatic liquid crystal polyester resin.

The thickness of the coating layer is preferably 100 μm or less, more preferably 50 μm or less. When the thickness of the coating layer exceeds 100 μm, the dielectric breakdown voltage and the like increase as the thickness increases, but since it is bulky when processing the enamel wire into a coil shape, it is difficult to respond to the recent trend toward miniaturization of electronic and electric devices. Tend.

The thus-obtained enameled wire of the present invention has a low water absorption rate and a low dielectric constant and dielectric loss, so that it can be used for high-frequency compatible equipment which is difficult to cope with with conventional enameled wires. It will be possible.

[0021]

EXAMPLES Next, the present invention will be described based on examples, but it goes without saying that the present invention is not limited to the examples. [Water Absorption] The film was allowed to stand in a constant temperature and humidity layer of 85 ° C. × 85% RH until the weight of the film became constant, and the water absorption was calculated from the weight difference before and after the standing. [Dielectric Properties] HP 4291 manufactured by Hewlett-Packard Company
The dielectric constant and dielectric loss of the film were measured at 1 GHz and 1 KHz using an RF impedance / material analyzer.

Production Example 1 759.7 g (5.50 mol) of p-hydroxybenzoic acid was added to a reactor equipped with a stirrer, a torque meter, a nitrogen gas introducing tube, a thermometer and a reflux condenser. Dihydroxybiphenyl 63.3 g (2.75 mol), isophthalic acid 457.4 g (2.75 mol) and acetic anhydride 123
5.4 g (12.10 mol) was charged. After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 ° C. over 15 minutes in a nitrogen gas stream, the temperature was maintained, and the mixture was refluxed for 3 hours. Then, the by-produced acetic acid and unreacted acetic anhydride which flow out were distilled off, the temperature was raised to 320 ° C. over 170 minutes, the temperature was maintained for 3 hours to complete the reaction, and the contents were taken out. The obtained solid content was cooled to room temperature, pulverized with a coarse pulverizer, and then the polymerization reaction was proceeded in a solid layer under a nitrogen atmosphere. The polymerization reaction was maintained at 20 ° C. for 30 minutes to sufficiently replace the nitrogen gas in the system, and then the temperature was raised to 200 ° C. over 1 hour. Furthermore, the temperature was raised to 260 ° C. over 5 hours, the temperature was maintained for 10 hours, and then the temperature was lowered to terminate the reaction.

Example 1 10 g of the aromatic liquid crystal polyester resin powder obtained in Production Example 1 was added to 90 g of p-chlorophenol and heated to 120 ° C. with stirring to obtain a transparent varnish. This varnish was cast on a glass plate using an applicator with a clearance of 360 μm. Then, after heating for 1 hour on a hot plate at 100 ° C, it was dried in a hot air oven at 180 ° C and 250 ° C for 1 hour each, and the dry film thickness was 25.
A film of μm was obtained. The water absorption of this film is 0.1
% Or less, dielectric constant 2.8 (1 GHz), dielectric loss 0.00
It was 4 (1 GHz). The results are shown in Table 1.

Comparative Example 1 The dielectric properties of a polyimide (PI) film were measured using industrial materials vol.
14 No. 6 p62 (1993). As a result, it was found that each performance was inferior to the aromatic liquid crystal polyester film described in Example 1 (Table 1).

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to provide an enameled wire which has a low water absorption rate, does not corrode the conductive wire, and has excellent dielectric characteristics.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Okamoto             6 Kitahara, Tsukuba, Ibaraki Sumitomo Chemical Co., Ltd.             In the company (72) Inventor Manabu Hirakawa             6 Kitahara, Tsukuba, Ibaraki Sumitomo Chemical Co., Ltd.             In the company F-term (reference) 4J038 DD061 JA64 KA06 NA03                       NA04 NA21 PB09 PC02                 5G305 AA02 AB10 AB12 BA18 CA11                       CB04 CD12 DA22                 5G309 MA11

Claims (3)

[Claims] 1. A varnish obtained by dissolving 0.5 to 100 parts by weight of an aromatic liquid crystal polyester resin in 100 parts by weight of a solvent containing a phenol compound represented by the following general formula (I) in an amount of 30% by weight or more. An enamel wire characterized by being coated with a conductive wire. (I) (In the formula, A represents a halogen atom or a trihalogenated methyl group, and i represents an integer of 1 or more and 5 or less. When i is 2 or more, plural A's may be the same or different. It may be.) 2. The enameled wire according to claim 1, wherein A is a chlorine atom. 3. An aromatic liquid crystal polyester resin, wherein the repeating structural unit derived from p-hydroxybenzoic acid is 30 to 80.
mol%, hydroquinone, resoncinol, 4,4'-dihydroxybiphenyl, repeating structural units derived from at least one compound selected from the group consisting of bisphenol A and bisphenol S, 10 to 35 mol%, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid The enameled wire according to claim 1 or 2, which comprises 10 to 35 mol% of repeating structural units derived from at least one compound selected from the group consisting of acids.