WO1991009441A1

WO1991009441A1 - Liquid crystal polymer for electric component insulation

Info

Publication number: WO1991009441A1
Application number: PCT/US1989/005693
Authority: WO
Inventors: William J. Strong, Iii
Original assignee: The Superior Electric Company; Nippon Petrochemicals Co., Ltd.
Priority date: 1989-12-12
Filing date: 1989-12-12
Publication date: 1991-06-27
Also published as: JPH04504643A

Abstract

Conventional insulating resins for electric motors, transformers, connectors or terminals have poor electrical, thermal and structural characteristics. Molded liquid crystal polymers of the invention offer improvements in these areas. In a typical embodiment, iron cores (2) around a shaft bearing (3) can be embedded in the liquid crystal polymer (1) by injection molding. Coils (4) can then be wound on the molded polymer surface.

Description

Liquid Crystal Polymer For Electric

Component Insulation

Detailed Description of the Invention

(1) Object of the Invention

(a) Field of Industrial Application

The present invention relates to an electric appliance such as a motor, a connector, a terminal plate, or a transformer and, more particularly, to a motor for various types of appliance such as a motor having excellent performance for, e.g., computer, communication, and industrial applications.

(b) Prior Art

In order to reduce the weight of a motor, various types of methods of using a resin as a material for parts of a motor have been conventionally adopted. Especially for an insulating portion of a stator, an insulating portion of a rotor, and a connector of a winding end portion, a material obtained by

impregnating a thermosetting resin in paper and curing the impregnated resin or a molded product of a thermoplastic resin is used. Since, however, these materials contain a thermosetting resin, it is

difficult to mold the materials into an arbitrary shape. In addition, since a special flame retarder is used in order to obtain flame retardant properties, electric characteristics are degraded. When a

thermoplastic resin, e.g., even a polyphenylenesulfide (PPS) having a high heat resistance is used, no

satisfactory size stability can be obtained with respect to a temperature change since its linear expansion coefficient is larger than that of a metal. In addition, a thin wall molding property, rigidity of a thin-walled product, and the like of a thermoplastic resin are not always satisfactory.

(c) Problems to be Solved by the Invention

The present invention solves the above problems of conventional techniques relating to an electric

appliance and, more particularly, to a motor.

(2) Arrangement of the Invention

(a) Means for Solving the Problems

The present invention provides, e.g., a motor, a connector, a terminal plate, or a transformer in which at least a part of an insulating portion consists of a molded product of a liquid crystal polymer and, more particularly, provides a motor having an excellent performance in which an insulating portion of a stator, an insulating portion of a rotor, or a connector used at an insulating portion of a winding end portion consists of a molded product of a liquid crystal polymer.

In a motor, examples of an insulating portion of a stator are a coil frame of a stator pole and a fixing frame of a stator magnet. The magnet used in the motor is a permanent magnet and an eleetromagnec and includes an iron core around which a coil is wound when no current flows.

Examples of an insulating portion of a rotor are a coil frame of a rotor pole and a fixing frame of a rotor magnet.

Examples of a connector to be used at an

insulating portion of a winding end portion are a connector having a wire connecting portion such as a lead wire for a winding end portion and a motor power source, and a connector having an internal printed circuit. In particular, a connector including a portion requiring a soldering step is effective.

A liquid crystal polymer used in the present invention is a thermoplastic fusible polymer which exhibits optical anisotropy upon fusing. Such a polymer exhibiting optical anisotropy upon fusing has a property in that a polymer chain has a regular parallel arrangement in a fused state. The property of an optical anisotropic fused phase can be checked by a conventional polarization test method using an

orthogonal polarizer.

Examples of the liquid crystal polymer are liquid crystal polyester, liquid crystal polycarbonate, and liquid crystal polyesterimide. More specifically, examples are (all) aromatic polyester, polyesteramide, polyamideimide, polyestercarbonate, and polyazomethine.

The liquid crystal polymer is generally

manufactured from a monomer having a plurality of chain extending bonds which are elongated and flat, have high rigidity along a long chain of molecules, and are coaxial with or parallel each other.

Examples of a composition of the polymer for forming an optical anisotropic fused phase as described above are:

(A) at least one of aromatic dicarboxylie acids and alicyclic dicarboxylie acids;

(B) at least one of aromatic hydroxycarboxylic acids;

(C) at least one of aromatic diols, alicyclic diols, aliphatic diols;

(D) at least one of aromatic dithiols, aromatic thiσphenols, aromatic thiolcarboxylie acids; and

(E) at least one of aromatic hydroxyamines and aromatic diamines.

Although the above compounds can be singly used, they are often used in a combination of, e.g., (A) and (C); (A) and (D); (A), (B), and (C); (A), (B), and (E)'; or (A), (B), (C), and (E).

(A1) Examples of the compounds constituting the above-mentioned polymers include aromatic dicarboxylie acids such as terephthalic acid,

4,4'-diphenyldicarboxylic acid,

4,4'-triphenyldicarboxylic acid,

2,6-naphthalenedicarboxylic acid,

1,4-naphthalenedicarboxylic acid,

2,7-naphthalenedicarboxylic acid, diphenyl

ether-4,4'-dicarboxylie acid,

diphenoxyethane-4,4'-dicarboxylie acid,

diphenoxybutane-4,'4'-dicarboxylie acid,

diphenylethane-4,4'-dicarboxylie acid, isophthalic acid, diphenyl ether-3,3'-dicarboxylie acid,

diphenoxyethane-3,3'-dicarboxylie acid,

diphenylethane-3,3'-dicarboxylie acid, and

1,6-naphthalenedicarboxylie acid: and those substituted with alkyl and alkoxy groups and halogen atoms, such as chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, and ethoxyterephthalic acid.

(A2) Examples of the alicyclic dicarboxylie acids include trans-1,4-cyclohexanedicarboxylic acid,

cis-1,4-cyclohexanedicarboxylic acid, and

1,3-cyclohexanedicarboxylic acid as well as those substituted with alkyl and alkoxy groups and halogen atoms, such as

trans-1,4-(2-methyl)cyclohexanedicarboxylic acid and trans-1,4-(2-chloro)cyclohexanedicarboxylic acid.

(B) Examples of the aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and

6-hydroxy-1-naphthoic acid as well as those substituted with alkyl and alkoxy groups and halogen atoms, such as 3-methyl-4-hydroxybenzoic acid,

3,5-dimethyl-4-hydroxybenzoic acid,

2,6-dimethyl-4-hydroxybenzoic acid,

3-methoxy-4-hydroxybenzoic acid,

3,5-dimethoxy-4-hydroxybenzoic acid,

6-hydroxy-5-methyl-2-naphthoic acid,

6-hydroxy-5-methoxy-2-naphthoic acid,

3-chloro-4-hydroxybenzoic acid,

2-chloro-4-hydroxybenzoic acid,

2,3-dichloro-hydroxybenzoic acid,

3,5-dichloro-4-hydroxybenzoic acid,

2,5-dichloro-4-hydroxybenzoic acid,

3-bromc-4-hydroxybenzoic acid,

6-hydroxy-5-chloro-2-naphthoic acid,

6-hydroxy-7-chloro-2-naphthoic acid, and

6-hydroxy-5,7-dichloro-2-naρhthoic acid.

(C1) Examples of the aromatic diols include hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxytriphenyl, 2,6-naphthalenediol,

4,4'-dihydroxydiphenyl ether,

bis(4-hydroxyphenoxy)ethane, 3,3'-dihydroxydiphenyl,

3,3'-dihydroxydiphenyl ether, 1,6-naρhthalenediol,

2,2-bis(4-hydroxyphenyl) propane, and

2 ,2-bis(4-hydroxyphenyl)methane as well as those substituted with alkyl and alkoxy groups and halogen atoms, such as chlorohydroquinone, methylhydroquinone,

1-butyIhydroquinone, phenyIhydroquinone,

methoxyhydroquinone, 1-butyIhydroquinone,

phenyIhydroquinone, methoxyhydroquinone,

phenoxyhydroquinone, 4-chlororesorcinol, and

4-methylresorcinol.

(C2) Examples of the alicyclic diols include trans-1,4-cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexanedimethanol,

cis-1,4-cyclohexanedimethanol,

trans-1,3-cyclohexanedimethanol,

cis-1,3-cyclohexanediol, and trans-1,3-cyclohexanediol as well as those substituted with alkyl and alkoxy groups and halogen atoms, such as

trans-1,4-(2-methyl)cyclohexanediol and

trans-1,4-(2-chloro)cyclohexanediol.

(C3) Examples of the aliphatic diols include straight-chain or branched-chain aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyl glycol. (Dl) Examples of the aromatic dithiols include benzene-1,4-dithiol benzene-1,3-dithiol,

2,6-naphthalenedithiol, and 2 , 7-naphthalenedithiol .

(D2) Examples of the aromatic thiolphenols include 4-mercaptophenol, 3-mercaptophenol,

6-mercaptophenol, and 7-mercaptophenol.

(D3) Examples of the aromatic thiol carboxylic acids include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid, and

7-mercapto-2-naphthoic acid.

(E) Examples of the aromatic hydroxyamines and aromatic diamines include 4-aminophenpol,

N-methyl-4-amino-phenol, 1,4-phenylenediamine,

N-methyl-1,4-phenylenediamine,

N,N'-dimethyl-1,4-phenylenediamine, 3-aminophenol, 3-methyl-4-amincphenol, 2-chloro-4-aminophenol,

4-amino-1-naphthol, 4-amino-4'-hydroxydiphenyl,

4-amino-4'-hydroxydiphenyl ether,

4-amino-4'-hydroxyphenylmethane,

4-amino-4'-hydroxydiphenyl sulfide, 4,4'-diaminophenyl sulfide (thiodianiline), 4,4'-diaminodiphenyl sulfone, 2,5-diaminotoluene, 4,4'-ethylenedianiline,

4,4'-diaminodiphenoxyethane,

4,4'-diaminodiphenylmethane (methylenedianiline), and 4,4'-diaminodiphenyl ether (oxydianiline).

The liquid crystal polymer used in the present invention can be manufactured by various types of ester forming methods such as a fusing acidolyβis method and a slurry polymerization method by using the above compounds.

The liquid crystal polymer used in the present invention includes a polymer in which a part of one polymeric chain is constituted by a segment of a polymer for forming an anisotropic fused phase while the remaining part is constituted by a segment of a thermoplastic resin not forming an anisotropic fused phase. The liquid crystal polymer also includes a polymer combining a plurality of liquid crystal polymers.

Of these liquid crystal polymer, a preferable example is a (co) polymer containing a monomer unit represented by a formula:

More specifically, such (co)polymers are:

(I)

(II)

(III)

This liquid crystal polymer preferably has a heat deformation temperature of 150ºC or more, and most preferably, 230ºC or more under a load of 18.6 kg/cm² (this condition will be the same hereinafter unless otherwise specified). When the heat deformation temperature is less than 150ºC, deformation may be caused by a temperature increase upon driving of a motor. When it is desired to perform a soldering step' for an insulating portion of a stator, an insulating portion of a rotor, or a connector of an insulating portion of a winding end portion, a soldering heat resistance is required. In this case, a heat

deformation temperature of the liquid crystal polymer is preferably 230°C or more.

The liquid crystal polymer can contain various types of inorganic fillers as long as it does not fall outside the range of the scope of the present

invention. The inorganic filler used in the present invention is not particularly limited. Examples of the inorganic filler are molybdenum disulfide, talc, mica, clay, sericite, calcium carbonate, calcium silicate, silica, alumina, aluminum hydroxide, calcium hydroxide, graphite, potassium titanate, a glass fiber, a carbon fiber, and various types of whisker. An addition amount of such an inorganic filler is 10 to 70 parts by weight, and preferably, 25 to 60 parts by weight with respect to 100 parts by weight of the liquid crystal polymer. By adding such a filler to the liquid crystal polymer in an arbitrary amount, dimensional precision, mechanical properties, and the like of the polymer can be improved.

Although a method of manufacturing a molded product of an insulating portion of a stator, an insulating portion of a rotor, or a connector to be used as an insulating portion of a winding end portion from the liquid crystal polymer is not particularly limited, injection molding is preferred to facilitate molding.

(b) Embodiments

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Figs. 1 and 2 show the first embodiment of the present invention in which an insulating portion of a stator consists of a molded product of the liquid crystal polymer.

Referring to Fig. 1, a grade (heat deformation temperature under a load of 18.6 kg = 330ºC) of a terpolymer (Zider (tradename) available from U.S. Amoco Performance Products Co.) of 4-hydroxy benzoate, biphenol, and terephthalic acid and containing a glass fiber and talc is used as a luquid crystal polymer. Coil frames of a stator pole as shown in Fig. 1 are manufactured by injection molding. The coil frames consisting of a liquid crystal polymer 1 are provided around iron cores 2, and a winding 4 is wound around each coil frame. One flange of each coil frame is cylindrically connected and fixed.

Fig. 2 shows a fixing frame of stator magnets formed by injection molding using a liquid crystal polymer similar to that shown in Fig. 1. Referring to Fig. 2, magnets are embedded in predetermined positions of the liquid crystal polymer.

Figs. 3 and 4 show the second embodiment of the present invention in which an insulating portion of a rotor consists of a molded product of a liquid crystal polymer.

Fig. 3 shows a coil frame of a rotor pole of a motor manufactured by injection molding. Referring to Fig. 3, the number of iron cores corresponding to the number of poles are embedded around a shaft of a liquid crystal polymer, and a winding is wound around the liquid crystal polymer. This structure can be molded by inserting the iron cores and the shaft.

Fig. 4 shows a fixing frame of a rotor magnet of a motor. This structure can be manufactured by insert molding similar to the structure shown in Fig. 3. More specifically, this structure is constituted by a shaft, a bearing 3 located around the shaft, and a cylindrical liquid crystal polymer located around the bearing 3 and having iron cores 2 embedded therein.

Fig. 5 shows the third embodiment of the present invention in which a connector to be used as an

insulating portion of a winding end portion consists of a molded product of a liquid crystal polymer. A connector as shown in Fig. 5 is manufactured by injection molding using a liquid crystal polymer similar to the liquid crystal polymer used as the insulating portion of the stator shown in Figs. 1 and 2. Referring to Fig. 5, the connector includes a printed circuit (not shown) therein, and connector pins 5 are formed as external leads. Terminal winding holding holes 7 and terminal soldering portions 6 for soldering windings are also formed. When a connector includes the terminal soldering portions 6 as shown in Fig. 5, the liquid crystal polymer used in the present invention preferably has a soldering heat resistance, when a liquid crystal polymer having a high heat deformation temperature is used, a connector consisting of the liquid crystal polymer is not damaged in a soldering step, and the soldering step can be easily performed.

Since any structure shown in Figs. 1 to 5 is molded by using a liquid crystal polymer, its

dimensional precision, dimensional stability of a complicated shape, and heat resistance are good.

Mechanical strength and electrical characteristics are also excellent.

In addition, since a motor is assembled by using parts manufactured as described above, its weight can be reduced.

Furthermore, since parts consisting of the liquid crystal polymer of the present invention are used, noise produced by a motor is significantly reduced, and operation characteristics of the motor are good. (c) Effects of the Invention

As has been described above, an electric appliance of the present invention in which at least a part of an insulating portion consists of a molded product of a liquid crystal polymer can be made compact and can reduce noise. In addition, by using the liquid crystal polymer, physical properties such as a fire retardant property, an oil resistance, a chemical resistance, and an electrical insulation property can be improved.

Especially when the molded product of the liquid crystal polymer is used as an insulating portion of a stator of a motor, an insulating portion of its rotor, or a connector used as an insulating portion of its winding end portion, a motor having good physical characteristics can be provided.

4. Brief Description of the Drawings

Fig. 1 is a schematic view showing an embodiment of an insulating portion (coil frame of a stator pole) of a stator of a motor according to the present

invention;

Fig. 2 is a schematic view showing an embodiment of an insulating portion (fixing frame of a stator magnet) of a stator of a motor according to the present invention;

Fig. 3 is a schematic view showing an embodiment of an insulating portion (coil frame of a rotor pole) of a rotor of a motor according to the present invention;

Fig. 4 is a schematic view showing an embodiment of an insulating portion (fixing frame of a rotor magnet) of a rotor of a motor according to the present invention; and

Fig. 5 is a schematic view showing an embodiment of a connector of a motor according to the present invention.

Claims

1. An electric appliance, wherein at least a part of an insulating portion consists of a molded product of a liquid crystal polymer.

2. An appliance according to claim 1, wherein at least a part of an insulating portion of a motor consists of a molded product of a liquid crystal polymer.

3. An appliance according to claim 1, wherein at least a part of an insulating portion of a connector, a terminal plate, or a transformer consists of a molded product of a liquid crystal polymer.

4. An appliance according to claim 1, 2, or 3, wherein a heat deformation temperature of said liquid crystal polymer under a load of 18.6 kg/cm is not less than 150°C.

5. An appliance according to claim 1, 2, 3, or 4, wherein said liquid crystal polymer is an aromatic polyester containing at least a monomer unit

represented by the following formula:

6. A motor according to claim 2, wherein said insulating portion is a stator, a rotor, or a connector provided at a winding end portion.

7. A motor according to claim 6, wherein a part of an insulating portion of said stator is a coil frame of a stator pole or a fixing frame of a stator magnet.

8. A motor according to claim 6, wherein a part of an insulating portion of said rotor is a coil frame of a rotor pole or a fixing frame of a rotor magnet.