JPH07118376A - Electrical polyester insulator - Google Patents

Abstract

PURPOSE:To diminish temp. dependence of polyester and a decrease in electrical resistivity, widen the range of processing temps., and improve moldability and electrical insulating properties by incorporating a copolymer obtained by copolymerizing a specific acid component with a specific diol component. CONSTITUTION:A monomer mixture which comprises an acid component consisting of terephthalic acid and/or diethyl terephthalate and a diol component consisting of a 2,2-dialkyl-1,3-propanediol (a) wherein the alkyls are selected from ethyl, propyl, butyl, pentyl, and hexyl and ethylene glycol (b) in an (a)/(b) ratio of 3/97 to 50/50 by mol, and which may optionally contain an aromatic carboxylic acid, an aliphatic dicarboxylic acid, a polyol, etc., is reacted by (trans)esterification. The resulting ester is condensation-polymerized to obtain a copolyester having an intrinsic viscosity of 0.3-1.2dl/g. This copolyester is dried to a water content of 3,000ppm or lower, melted with an extruder at 260-300 deg.C, and then molded through quenching to 50-60 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electric equipment, electronic equipment,
The present invention relates to an electric insulator used for electric wires and the like, and more specifically, it has a high electric resistivity, and even if it is used in daily use, in water, or under high temperature and high humidity, the electric resistivity does not decrease so much, a film, The present invention relates to a polyester electric insulator useful for heat shrink films, sheets, flexible printed circuit boards and the like.

[0002]

2. Description of the Related Art High-density polyethylene, high-density polypropylene and vinyl chloride resin, which are plastics having a relatively high volume resistivity, have been conventionally used for electrical insulators. However, none of these general-purpose plastics is sufficient as an electrical insulator having a volume resistivity of about 10 ¹⁴ to 10 ¹⁶ Ω · cm. Therefore, as a method of increasing the volume resistivity, Japanese Patent Application Laid-Open No. 56-159242 discloses a method of adding a copolymer of styrene and phthalic anhydride to a vinyl chloride resin. But,
In this method, a plasticizer such as DOP and a stabilizer such as metal soap, which are other additives added to the vinyl chloride resin, adversely affect the volume resistivity or cause bleeding, etc. It needs to be restricted, making it unsuitable for various applications. In addition, the molded product obtained from the resin composition has a drawback that it is difficult to dispose of it. Recently, it has a relatively low price, is chemically stable, has a large mechanical strength, and has excellent heat resistance and cold resistance despite its excellent volumetric resistivity of 10 ¹⁶ to 10 ¹⁷ Ω · cm. Since the above is also good, a polyester material has come to the spotlight as a raw material of the electric insulating material, and the polyester occupies most of the electric insulating material.

However, the conventional polyester has a large temperature dependency in that the volume resistivity greatly changes depending on the use temperature, so that a stable electrical insulator cannot be obtained, and the polyester is underwater or in a hot and humid environment. When used below, it has a drawback that it is prone to deterioration because it causes a hydrolysis reaction.As a result, the presence of a hydrolyzate and the like in the polyester, especially, a hydrolyzate with a charge has an effect. The volume resistivity was greatly reduced. Further, since the conventional polyester has crystallinity, the processing temperature range is narrow and the flow is poor, so that the molding processability is poor.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and the electric resistivity is less likely to decrease even in daily use, in water and under high temperature and high humidity. The present invention provides a polyester electric insulator having excellent electric insulating properties, which is useful for heat shrink films, sheets, flexible printed boards and the like.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies, the present inventors have found that terephthalic acid or / and terephthalic acid diester, ethylene glycol and a specific 2,2-alkyl-substituted-1,3-propanedio It was found that a polyester electric insulator using a specific polyester copolymer obtained by copolymerizing styrene-polyvinyl alcohol has excellent effects on the above problems, and completed the present invention.

The present invention has the following configuration. (1) Terephthalic acid or / and terephthalic acid diester as an acid component, ethylene glycol and an alkyl substituent as a diol component are selected from ethyl group, propyl group, butyl group, pentyl group and hexyl group 2,2 -Alkyl-substituted-1,3-propanediol, an acid component and a diol component as main components, and an intrinsic viscosity obtained by a copolymerization reaction is 0.3 to 1.
Polyester electrical insulator using 2 dl / g polyester copolymer. (2) 2,2-alkyl substitution constituting the diol component-
The polyester electrical insulator according to the above-mentioned item 1, wherein the molar ratio of 1,3-propanediol and ethylene glycol is in the range of 3/97 to 50/50. (3) At a temperature equal to or lower than the glass transition point of the polyester copolymer constituting the test piece molded under the following conditions by 2 ° C. or less, the temperature change with respect to the common logarithm of the volume resistivity of the test piece is 0. 2. The polyester electric insulator according to the above item 1, which has a temperature of 0.02 / ° C. or less. The pelletized polyester copolymer was heated and melted using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C, extruded into a sheet, and then rapidly cooled and solidified by a casting drum at 60 ° C to be transparent. A sheet having a thickness of 0.5 mm was obtained, and the sheet was stretched at a stretching rate of 300% / mi using a biaxial stretching machine in a nitrogen gas atmosphere in which the temperature was set to 90 to 110 ° C.
Simultaneous biaxial stretching of 3 times × 3 times with n is performed to obtain a 0.05 mm film, which is used as a test piece. (4) Difference in common logarithm between the volume resistivity of the test piece and the volume resistivity of the test piece before immersion when the test piece molded under the following conditions was immersed in a water bath at a liquid temperature of 25 ± 1 ° C. for 14 days. And a test piece molded under the following conditions, 50 ° C relative humidity 90%
The difference in the common logarithm between the volume resistivity of the test piece when left to stand for 14 days in the constant temperature and humidity chamber set to above and the volume resistivity of the test piece before being left is all less than 1 above. Polyester electrical insulation. The pelletized polyester copolymer was melted by heating using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C, extruded into a sheet, and then rapidly solidified by a casting drum at 60 ° C to be transparent. A sheet having a thickness of 0.5 mm is obtained and used as a test piece.

The polyester copolymer according to the present invention is
Ethylene glycol and specific 2,2-alkyl substitution-
It is obtained by using a diol component composed of 1,3-propanediol and an acid component composed of terephthalic acid or / and a terephthalic acid diester as main components and subjecting them to a copolymerization reaction. The diol component used for the copolymerization is ethylene glycol and 2,2-alkyl-substituted-
The molar ratio of 1,3-propanediol is 97 / 3-50.
It is preferably / 50. 2,2-alkyl substitution-
When the content of 1,3-propanediol is less than 3 mol%, the viscosity reducing effect of lowering the melt viscosity of the polyester copolymer is poor, so that stable production of the polyester electrical insulator becomes difficult. Further, when it is used under humidification or in water, the volume resistivity remarkably decreases. On the contrary, when the content of 2,2-alkyl-substituted-1,3-propanediol exceeds 50 mol%, the degree of polymerization of the polyester copolymer is lowered, so that the mechanical strength of the polyester electric insulator is remarkably lowered. .

2,2-Alkyl-substituted according to the present invention
1,3-propanediol is one in which the alkyl substituent is selected from the group of ethyl, propyl, butyl, pentyl and hexyl, and specifically, 2,2-diethyl-1,3-propanediol. -(Hereinafter referred to as DMP), 2-butyl-2-ethyl-1,3-propanediol (hereinafter referred to as DMH), 2-pentyl-2-
Propyl-1,3-propanediol (hereinafter referred to as DMN) and 2-butyl-2-hexyl-1,3-propanediol (hereinafter referred to as DMU) are included. These can be used alone or in any combination depending on the purpose of use.

The polyester copolymer according to the present invention is
Terephthalic acid or / and terephthalic acid diester,
Ethylene glycol, 2,2-alkyl substituted-1,3-
As a component other than propanediol, for example, isophthalic acid, orthophthalic acid, 1,2-bis (4-carbophenoxy) ethane, 2,6-, as long as the characteristics of the copolymer do not impair the effects of the present invention. Aromatic carboxylic acids such as naphthalene dicarboxylic acid and trimellitic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and oxalic acid, propylene glycol, butylene glycol, bisphenol A, neopentyl glycol, Polyethylene glycol
Polyol, polypropylene glycol, glycerin, polyol such as pentaerythritol and the like may be contained as a copolymerization component.

As the method for polymerizing the polyester copolymer according to the present invention, various commonly used methods can be used. For example, terephthalic acid and a diol component are subjected to an esterification reaction, water generated by the reaction is distilled off, and then the pressure inside the reactor is gradually reduced to a high vacuum to remove the esterification reaction product inside. Polycondensation reaction method, transesterification reaction of terephthalic acid diester and diol component,
After distilling off the alcohol produced by the reaction, the pressure inside the reactor is gradually reduced to a high vacuum to cause a polycondensation reaction of the esterification reaction product inside, or terephthalic acid and terephthalic acid are used as acid components. There is a method in which both of the above methods are carried out simultaneously by using a mixture with an acid diester.

Manganese acetate, calcium acetate, zinc acetate or the like may be used as a catalyst for promoting the ester reaction between the acid component and the diol component, and antimony trioxide or oxidation may be used as a catalyst for promoting the polycondensation reaction of the esterified product. Known materials such as germanium, dibutyltin oxide and titanium tetrabutoxide may be used.

The polyester electrical insulation of the present invention may optionally contain stabilizers. Examples of the stabilizer include phosphoric acid compounds such as trimethyl phosphate and triphenyl phosphate, and hindered pheno-type compounds such as Irganox 1010.
However, other stabilizers may be used.

The polyester copolymer according to the present invention is
The intrinsic viscosity must be in the range 0.3-1.2 dl / g. When the intrinsic viscosity exceeds 1.2 dl / g, the melt viscosity becomes too high and stains occur in the orifice, making stable production for a long period of time difficult. On the other hand, if it is less than 0.3 dl / g, the mechanical strength of the polyester electrical insulator will be reduced. It is preferably 0.5 to 0.8 dl / g. The intrinsic viscosity was measured by using an Ubbelohde viscometer having a viscometer constant of 0.00956 and measuring the time for a predetermined amount of liquid to drop at 30 ° C. Specifically, the specific viscosity is defined as a value obtained by subtracting 1 from the value obtained by dividing the drop time of a predetermined amount of a solution (in which a polyester copolymer is dissolved in a solvent) by the drop time of the same amount of solvent, and determining the specific viscosity. By changing the addition amount of the copolymer and measuring the specific viscosity while changing the concentration of the solution, the reduced specific viscosity (specific viscosity / concentration of solution) was calculated, and the reduction ratio for each solution concentration was calculated. Plot the viscosity,
The value when the concentration was extrapolated to 0 was taken as the intrinsic viscosity.

Since the conventional polyester copolymer undergoes hydrolysis at the time of molding when water is present, a very small amount of water content (200 ppm or less) called absolute drying of the polyester copolymer is carried out before molding. Have to dry up. However, with the polyester copolymer according to the present invention, if the water content is 3000 ppm or less, a polyester electrical insulator can be easily obtained by a usual molding method. That is, if the water content is 3000 ppm, the drying step can be omitted. As a molding method, 260 to 3
The polyester copolymer is heat-melted by an extruder set to a temperature of 00 ° C, and the molten resin extruded from the die is heated to 50 to 60 ° C.
The method of rapidly cooling and solidifying on a casting drum is generally used, but it is not always necessary to follow this method. Further, if necessary, stretching may be carried out, and in general, a method of carrying out two-step sequential biaxial stretching of longitudinal uniaxial stretching, longitudinal and transverse simultaneous or longitudinal stretching and lateral stretching in a temperature range of 80 to 110 ° C. As a stretching method, there are a tenter method and a tube method. The polyester copolymer according to the present invention is amorphous or extremely close to amorphous,
Compared with conventional polyester copolymers that are crystalline, they have superior molding processability, so by selecting appropriate processing conditions, electrical insulation suitable for the intended use can be achieved without improving conventional processing machines. -Based polyester can be easily obtained.

The polyester electrical insulator of the present invention has a small temperature dependence of volume resistivity at a temperature below the glass transition point, and in particular, the temperature obtained by subtracting 2 ° C. from the glass transition point of the polyester copolymer used. In the temperature range below, the temperature dependence of the volume resistivity is extremely small, and a good volume resistivity can be stably maintained. Further, the volume resistivity of the electrical insulator is stable with little change even when exposed to high temperature and high humidity in water. By utilizing this excellent electric insulation property, it is possible to provide a highly reliable polyester electric insulation material for electric devices, electronic devices and electric wires.

The reason why the polyester electrical insulator of the present invention has an excellent electrical insulating property is not always clear, but it is 2,2-alkyl-substituted-1, which is a constituent component of the polyester copolymer of the present invention. Having two alkyl substituents possessed by 1,3-propanediol, so-called quaternary carbon, has the effect of improving heat resistance and inhibiting the transfer of electron carriers, at temperatures below the glass transition point. It can be presumed that the volume resistivity of will be kept stable.
Further, the reason why the polyester electrical insulator of the present invention has a small decrease in volume resistivity even under high temperature and humidity in water is that the alkyl substituent of the polyester copolymer according to the present invention is a hydrophobic group. Since it is possible to prevent the water molecule from reaching the ester bond part in the polyester copolymer, the hydrolysis reaction of the ester bond can be prevented and the generation of impurities accompanying the hydrolysis reaction can be mitigated.
It can be inferred that the decrease in volume resistivity is extremely small.

[0017]

The present invention will be specifically described in Examples. The physical property tests of polyester copolymers and the physical property tests (films, sheets) of molded polyester copolymers shown in Examples and Comparative Examples were carried out according to the following methods. 1. Physical property test of polyester copolymer (1) Measurement of molar ratio of diol component in polyester copolymer The molar ratio of diol component was measured using nuclear magnetic resonance spectrum. (2) Intrinsic viscosity measurement Using phenol / tetrachloroethane (6/4) as a solvent, the drop time of the solution was measured and calculated at 30 ° C. (3) Moisture content measurement The moisture content was measured by the Cal-Fisher method using a trace amount water content measuring device. (4) Measurement of glass transition point It was measured according to JIS-K7121 using a differential thermal scanning analyzer. 2. Physical Properties Test of Polyester Copolymer Molded Product (Film, Sheet) (1) Measurement of Intrinsic Viscosity Using phenol / tetrachloroethane (6/4) as a solvent, the drop time of the solution was measured at 30 ° C. and calculated. (2) Viscosity change rate A value obtained by subtracting the intrinsic viscosity of a polyester copolymer molded product from the intrinsic viscosity of the polyester copolymer, divided by the intrinsic viscosity of the polyester copolymer. The smaller this value is, the better the hydrolysis resistance is. (3) Crystallinity A flat panel camera was attached to the X-ray diffractometer, and an X-ray transmission photograph was taken to examine the crystallinity. It was visually evaluated that the non-crystalline material was A, the slightly crystallizable material was B, and the crystalline material was C. (4) Volume resistivity measurement Using an electric resistance measuring machine, with an applied voltage of 500 V, JI
It measured according to S-C2318. The larger this value is, the better the electric insulation is. (5) Water immersion treatment test Each test piece was placed in a water tank with a liquid temperature of 25 ± 1 ° C. for 1 day, 7 days, 1 day.
After soaking for 4 days, the volume resistivity of the test piece was measured.
The smaller the change in this value, the more stable the electrical insulator. (6) Constant temperature and high humidity treatment In a constant temperature and humidity chamber set to a temperature of 50 ° C and a relative humidity of 90%,
After leaving each test piece for 1, 7, and 14 days, the volume resistivity of the test piece was measured. The smaller the change in this value,
Represents a stable electrical insulator. (7) Constant Temperature Treatment Test Each test piece was placed in a constant temperature bath set at each temperature of 25, 35, 45, 55 and 65 ° C., and the volume resistivity of the test piece at a predetermined temperature was measured. The smaller the change in this value, the more stable the electrical insulator.

Example 1 A 10 L four-necked flask was charged with terephthalic acid (hereinafter referred to as TP).
Write A. ) Of 16.10 mol, DMH of 1.77 mol, zinc acetate of 0.011 mol as catalyst and antimony trioxide of 0.004 mol were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream, and 3 After removing 2 mol of water, ethylene glycol (hereinafter referred to as EG
Is written. 30.4 mol) was added dropwise, and heating was continued for 2 hours at the same temperature to remove 28.6 mol of water. Next, the flask was heated to 270 to 275 ° C., heated for 1 hour, depressurized to 0.3 to 0.5 Torr, and further heated to 280 to 285 ° C. Polycondensation was performed while removing unreacted diol (DMH and EG). The obtained polyester copolymer was granulated into pellets. The pellets had a water content of 2700 ppm, a glass transition point of 74 ° C. and an intrinsic viscosity of 0.76 dl / g. The molar ratio of the diol component in the polyester copolymer was EG / DMH = 90/10. The pelletized polyester copolymer is heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature is set to 270 to 285 ° C.,
After extruding into a sheet shape, it is rapidly cooled and solidified by a casting drum at 60 ° C. to obtain a transparent sheet having a thickness of 0.5 mm, and the sheet is heated at 90 to 110 ° C. under a nitrogen gas atmosphere of 2 Simultaneous biaxial stretching of 3 times × 3 times was performed using an axial stretching machine at a stretching speed of 300% / min to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Tables 1 and 2.

Example 2 A sheet having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that biaxial stretching was not performed, and the sheet was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Table 1.

Example 3 In a 10 L four-necked flask, 16.10 mol of TPA,
DMH 3.54 mol, zinc acetate 0.01% as a catalyst
1 mol, 0.004 mol of antimony trioxide were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream,
After removing 6.1 moles of water, add 2 EG to the flask.
8.7 mol was added dropwise, heating at the same temperature was continued for 2 hours, and 25.
6 moles of water were removed. Next, the flask is heated to 2
After heating to 70 to 275 ° C. and heating for 1 hour, the pressure in the flask is reduced to 0.3 to 0.5 Torr, and further 28
The temperature is raised to 0 to 285 ° C, and unreacted diol (DMH
And EG) were removed while polycondensation was performed. The obtained polyester copolymer was granulated into pellets. The pellets had a water content of 1100 ppm and a glass transition point of 69.
The inherent viscosity was 0.71 dl / g. Further, the molar ratio of the diol component in the polyester copolymer is EG / D
MH = 80/20. The pelletized polyester copolymer was heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., extruded in a sheet form, and then rapidly cooled and solidified by a casting drum at 60 ° C. to make it transparent. A sheet having a thickness of 0.5 mm is obtained, and the sheet is 90 to 1
Using a biaxial stretching machine in a nitrogen gas atmosphere whose temperature was set to 10 ° C., simultaneous biaxial stretching of 3 × 3 times at a stretching speed of 300% / min was performed to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Tables 1 and 2.

Example 4 In a 10 L four-necked flask, 16.10 mol of TPA,
DMH 5.31 mol, zinc acetate 0.01% as a catalyst
1 mol, 0.004 mol of antimony trioxide were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream,
After removing 9.4 moles of water, add 2 EG to the flask.
6.9 mol was added dropwise, and heating was continued for 2 hours at the same temperature.
2 mol of water was removed. Next, the flask is heated to 2
After heating to 70 to 275 ° C. and heating for 1 hour, the pressure in the flask is reduced to 0.3 to 0.5 Torr, and further 28
The temperature is raised to 0 to 285 ° C, and unreacted diol (DMH
And EG) were removed while polycondensation was performed. The obtained polyester copolymer was granulated into pellets. The pellet had a water content of 1700 ppm and a glass transition point of 66.
The inherent viscosity was 0.61 dl / g. Further, the molar ratio of the diol component in the polyester copolymer is EG / D
MH = 70/30. The pelletized polyester copolymer was heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., extruded in a sheet form, and then rapidly cooled and solidified by a casting drum at 60 ° C. to make it transparent. A sheet having a thickness of 0.5 mm is obtained, and the sheet is 90 to 1
Using a biaxial stretching machine in a nitrogen gas atmosphere whose temperature was set to 10 ° C., simultaneous biaxial stretching of 3 × 3 times at a stretching speed of 300% / min was performed to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Table 1.

Example 5 In a 10 L four-necked flask, 16.10 mol of TPA,
1.77 mol of DMP and 0.01 of zinc acetate as a catalyst
1 mol, 0.004 mol of antimony trioxide were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream,
After removing 3.1 moles of water, the flask was charged with 3 g of EG.
0.4 mol was added dropwise, heating was continued for 2 hours at the same temperature, and 28.
8 mol of water was removed. Next, the flask is heated to 2
After heating to 70 to 275 ° C. and heating for 1 hour, the pressure in the flask is reduced to 0.3 to 0.5 Torr, and further 28
The temperature is raised to 0 to 285 ° C, and unreacted diol (DMP
And EG) were removed while polycondensation was performed. The obtained polyester copolymer was granulated into pellets. The water content of the pellets was 2800 ppm, and the glass transition point was 71.
The inherent viscosity was 0.66 dl / g. Further, the molar ratio of the diol component in the polyester copolymer is EG / D
MP = 90/10. The pelletized polyester copolymer was heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., extruded in a sheet form, and then rapidly cooled and solidified by a casting drum at 60 ° C. to make it transparent. A sheet having a thickness of 0.5 mm is obtained, and the sheet is 90 to 1
Using a biaxial stretching machine in a nitrogen gas atmosphere whose temperature was set to 10 ° C., simultaneous biaxial stretching of 3 × 3 times at a stretching speed of 300% / min was performed to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Tables 1 and 2.

Example 6 In a 10 L four-necked flask, 16.10 mol of TPA,
DMN 7.08 mol, zinc acetate 0.01% as a catalyst
1 mol and 0.004 mol of antimony trioxide were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream,
After removing 2.6 moles of water, add 2 EG to the flask.
5.1 mol was added dropwise, heating was continued for 2 hours at the same temperature, and 19.
4 mol of water was removed. Next, the flask is heated to 2
After heating to 70 to 275 ° C. and heating for 1 hour, the pressure in the flask is reduced to 0.3 to 0.5 Torr, and further 28
The temperature was raised to 0 to 285 ° C, and unreacted diol (DMN
And EG) were removed while polycondensation was performed. The obtained polyester copolymer was granulated into pellets. The pellets had a moisture content of 1700 ppm and a glass transition point of 67.
The inherent viscosity was 0.56 dl / g. Further, the molar ratio of the diol component in the polyester copolymer is EG / D
MN = 60/40. The pelletized polyester copolymer was heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., extruded in a sheet form, and then rapidly cooled and solidified by a casting drum at 60 ° C. to make it transparent. A sheet having a thickness of 0.5 mm is obtained, and the sheet is 90 to 1
Using a biaxial stretching machine in a nitrogen gas atmosphere whose temperature was set to 10 ° C., simultaneous biaxial stretching of 3 × 3 times at a stretching speed of 300% / min was performed to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Table 1.

Comparative Example 1 In a 10 L four-necked flask, 16.10 mol of TPA,
EG 32.2 mol, zinc acetate 0.011 as a catalyst
Mol and antimony trioxide (0.004 mol) were charged, the flask was heated to 200 to 205 ° C. under a nitrogen stream, and the heating was continued for 2 hours to remove 32.0 mol of water. Next, the temperature of the flask was raised to 270 to 275 ° C., and after heating for 1 hour, the inside of the flask was 0.3 to 0.5 Torr.
The pressure was reduced to 2, and the temperature was further raised to 280 to 285 ° C., and polycondensation was performed while removing unreacted diol (EG). The obtained polyester copolymer was granulated into pellets. The pellets had a water content of 2100 ppm, a glass transition point of 79 ° C. and an intrinsic viscosity of 0.78 dl / g. Pelletized polyester copolymer 270-285
Using a T-die extruder in a vacuum atmosphere whose temperature is set to ℃,
Extrusion molding was carried out by heating and melting, but the target sheet could not be obtained due to defective molding.

Comparative Example 2 A film was obtained in the same manner as in Example 1 except that the pellet-shaped polyester copolymer obtained in Comparative Example 1 was used as the pellet-shaped polyester copolymer, to obtain a test piece.
Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Tables 1 and 2.

Comparative Example 3 The pelletized polyester copolymer obtained in Comparative Example 1 was used as the pelletized polyester copolymer, and the thickness was in accordance with Example 1 except that biaxial stretching was not carried out. A 0.5 mm sheet was obtained and used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Table 1.

Comparative Example 4 16.10 mol of TPA was added to a 10 L four-necked flask,
1.77 mol of NPG and 0.01% of zinc acetate as a catalyst
1 mol, 0.004 mol of antimony trioxide were charged, and the flask was heated to 200 to 205 ° C. under a nitrogen stream,
After removing 3.2 moles of water, the flask was charged with 3 EG.
0.4 mol was added dropwise, heating was continued for 2 hours at the same temperature, and 28.
7 mol of water was removed. Next, the flask is heated to 2
After heating to 70 to 275 ° C. and heating for 1 hour, the pressure in the flask is reduced to 0.3 to 0.5 Torr, and further 28
The temperature is raised to 0 to 285 ° C, and unreacted diol (NPG
And EG) were removed while polycondensation was performed. The obtained polyester copolymer was granulated into pellets. Moisture content of the pellets is 2300ppm, glass transition point is 75
The inherent viscosity was 0.90 dl / g. The molar ratio of the diol component in the polyester copolymer is EG / N
PG = 90/10. The pelletized polyester copolymer was heated and melted by using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C., extruded in a sheet form, and then rapidly cooled and solidified by a casting drum at 60 ° C. to make it transparent. A sheet having a thickness of 0.5 mm is obtained, and the sheet is 90 to 1
Using a biaxial stretching machine in a nitrogen gas atmosphere whose temperature was set to 10 ° C., simultaneous biaxial stretching of 3 × 3 times at a stretching speed of 300% / min was performed to obtain a 0.05 mm film, which was used as a test piece. Using the obtained test piece, the physical property test of the polyester copolymer molded article was measured according to the above measuring method. The results are shown in Table 1.

As can be seen from Table 1, the polyester electrical insulator of the present invention shows an extremely small decrease in volume resistivity even when exposed to water or high temperature and high humidity, and exhibits an excellent value of less than 1 in common logarithm. It was Further, as can be seen from FIG. 1, the polyester electrical insulator of the present invention exhibits a volume resistivity of 7 × 10 ¹⁶ Ω · cm or less at the glass transition point of the polyester copolymer constituting the electrical insulator or less. The maximum change in volume resistivity with respect to temperature was 0.02 / ° C or less in the common logarithm, indicating extremely excellent stability. It can be seen that the polyester electrical insulator of the present invention has an extremely small difference in intrinsic viscosity from the polyester copolymer used and is excellent in hydrolysis resistance. And since the hydrolyzate is minute, foaming does not occur during molding,
A polyester electric insulator having excellent surface smoothness and transparency and a good texture can be obtained.

[0029]

EFFECT OF THE INVENTION In the conventional polyester electrical insulator, the volume resistivity is significantly lowered in water and under high temperature and high humidity because the polyester constituting the electrical insulator is apt to undergo hydrolysis due to its chemical structure. Further, the temperature dependence of the volume resistivity with respect to the temperature below the glass transition point was also large.
In contrast, the polyester electrical insulator of the present invention,
Since the polyester copolymer having 2,2-alkyl-substituted-1,3-propanediol is used, the electrical resistivity is less likely to decrease even in daily use or in water and under high temperature and high humidity. It is possible to obtain a polyester electric insulator having excellent electric insulation useful for a film, a heat shrinkable film, a sheet, a flexible printed circuit board and the like. Therefore,
INDUSTRIAL APPLICABILITY The polyester electric insulator of the present invention has a very stable volume resistivity and a severe environment such as water and high temperature / humidity, which cannot be obtained by the conventional polyester electric insulator, as a material used for electric devices, electronic devices and electric wires. It has the property that it is also suitable for the bottom.

[0030]

[Table 1]

[0031]

[Figure 1]

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[Procedure amendment]

[Submission date] May 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 Temperature of a polyester copolymer molded article obtained in Examples 1, 3, 5 and Comparative Example 2 (25 to 60 ° C.)
It is the correlation diagram which plotted the volume resistivity (common logarithm) which changes with respect to.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Delete

Claims (4)

[Claims] 1. A terephthalic acid or / and a terephthalic acid diester as an acid component, an ethylene glycol and an alkyl substituent as an ethyl group or a propyl group as a diol component,
A 2,2-alkyl-substituted-1,3-propanediol selected from any of a butyl group, a pentyl group and a hexyl group is used, and the acid component and the diol component are the main components, and a copolymerization reaction is performed. Obtained intrinsic viscosity 0.3-
A polyester electrical insulator characterized by using a 1.2 dl / g polyester copolymer. 2. A molar ratio of 2,2-alkyl-substituted-1,3-propanediol and ethylene glycol constituting the diol component is in the range of 3/97 to 50/50. The polyester electrical insulator according to claim 1. 3. A temperature change with respect to the common logarithm of the volume resistivity of the test piece at a temperature not higher than 2 ° C. below the glass transition point of the polyester copolymer constituting the test piece molded under the following conditions. , 0.02 / ° C or less, The polyester electrical insulator according to claim 1, wherein The pelletized polyester copolymer was heated and melted using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C, extruded into a sheet, and then rapidly cooled and solidified by a casting drum at 60 ° C to be transparent. A sheet having a thickness of 0.5 mm was obtained, and the sheet was stretched at a stretching rate of 300% / mi using a biaxial stretching machine in a nitrogen gas atmosphere in which the temperature was set to 90 to 110 ° C.
Simultaneous biaxial stretching of 3 times × 3 times with n is performed to obtain a 0.05 mm film, which is used as a test piece. 4. A test piece molded under the following conditions has a liquid temperature of 25 ±
The difference in the common logarithm between the volume resistivity of the test piece when immersed in a water tank at 1 ° C for 14 days and the volume resistivity of the test piece before immersion, and a test piece molded under the following conditions, 50 ° C relative humidity 90% The difference in the common logarithm between the volume resistivity of the test piece when left to stand for 14 days in the constant temperature and humidity chamber set to 1 and the volume resistivity of the test piece before being left is all less than 1. The polyester electric insulator according to claim 1. The pelletized polyester copolymer was heated and melted using a T-die extruder in a vacuum atmosphere whose temperature was set at 270 to 285 ° C, extruded into a sheet, and then rapidly cooled and solidified by a casting drum at 60 ° C to be transparent. A sheet having a thickness of 0.5 mm is obtained and used as a test piece.