JPS5941327A - Polyester electrical insulating material - Google Patents

Abstract

PURPOSE:To provide a polyester electrical einsulating material having extremely low hygroscopicity and improved dimensional stability to moisture, and composed of a polyester free from hydrophilic group and containing reduced amount of active terminal groups. CONSTITUTION:A polyester wherein the sum of the terminal OH groups and terminal carboxyl groups is <=90%, preferably <=20% of the whole terminal groups, free from hydrophilic group, and having an intrinsic viscosity of >=0.4, is prepared, e.g. by adding a terminal-blocking agent such as diphenyl carbonate, etc. to the polymer at a stage before the completion of the polymerization and after the polymerization degree is increased to an extent, thereby reacting the agent to the active terminal groups of the polyester. The objective insulating material is prepared by using the polyester.

Description

[Detailed description of the invention] The present invention relates to electrically insulating materials made of polyester.

The present invention mainly relates to an electrical insulation material made of polyester having ultra-low moisture absorption and improved moisture absorption dimensional stability.

Traditionally, polyester has been widely used in the form of films, sheet tubes, or fibers (woven and knitted fabrics, etc.) for electrical insulation purposes as a material with well-balanced mechanical performance, heat resistance, solvent resistance, electrical performance, etc. It is provided. In order to respond to the recently advanced equipment performance for these applications,
There is an increasing demand for electrically insulating materials that are superior in terms of materials. One of the directions for the development of materials suitable for this purpose is the development of new materials, and the other is the modification of materials already used in this application field, such as polygosteel.
'j It can be achieved by increasing the sophistication. However, in the former direction, even if high performance is achieved in some physical properties, other properties are often inferior.

It is an object of the present invention to provide an ultra-low hygroscopic polyester electrical insulating material that can meet the sophisticated performance requirements to the point where the hygroscopic behavior is negligible even in the case of a conventional type.

According to the study results of the present inventors, this ultra-low moisture absorption polyester electrical insulation material has the following electrical insulation properties due to moisture absorption:
It was found that it exhibited outstanding performance that had not been achieved previously.

That is, the present invention provides an electrical insulating material made of polyester, in which the polyester has an intrinsic viscosity of 0.4 or more, and the sum of terminal hydroxyl groups and carboxyl groups is 90% of the total terminal group amount.
% or less and does not contain any hydrophilic groups.

In this article, polynisdel refers to ethylene terephthalate or ethyne-26-naphthalate as the main repeating unit (1'l-), but some of its [ν component and/or glycol component is may be replaced with an acid component and/or another acid component or another glycol component. Examples of such a third component include inphthal (g, 1.s-naphthalene dicarboxylic acid, 2 .7-naphthalene dicarboxylic acid, 4
．． 4'-diphenyl dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic fR, 4,4'-diphenylsulfone dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid WI+ p-β-human tetraxyethoxybenzoic acid, adipic acid, azelain acid, cepatic acid.

Hexahydroterephthalic acid, hexahydroisophthalic acid, 6-oxycaproic acid, trimethylene glycol, tetramethylene glycol, hexamethylene glycol,
decamethylene glycol, neopentylene gellicol,
such as 1,1-cyclohexane dimetatool, 1,4-cyclohexane dimetatool, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl)sulfone and the like; Examples include functional derivatives of these. These may have one glaze (or two or more glazes). In addition, polyesters can be used as long as they are substantially linear, such as pentaerythritol, trimethylolpropane, trimellitic acid, trimethenoic acid, and their functions. It may be a copolymer of one or more polyfunctional compounds such as functional derivatives and/or one or more monofunctional compounds such as o-benzoylbenzoic acid, methoxypolyethylene glycol, and functional derivatives thereof.

Polyester has stabilizers (e.g. heat, UV rays).

stabilizers against oxygen), lubricants, pigments, fillers.

Although additives such as a mold release agent, an antistatic agent, and a nucleating agent may be added, it is preferable to use highly stable additives.

In the present invention, the above-mentioned polyester is polymerized, and at any stage until the end of producing a support base film or sheet-like product, or a fiber or woven product by melt-rolling or spinning and stretching by a conventional method, The combined amount of hydroxyl groups and carboxyl groups is 90 or less, preferably 60 or more, more preferably 40% or less, and most preferably 20% or less of the total amount of terminal groups. As a result, surprisingly, it is possible to extremely reduce the moisture content, and as a result, it is possible to significantly reduce the deterioration in edge quality and dimensional changes due to moisture absorption. The method of converting this terminal group to make it insoluble in water does not itself limit the present invention, but a suitable method is, for example, to increase the degree of polymerization to a certain degree before the polymerization of the polymer is completed. There is a method in which an appropriate amount of a terminal stabbing agent such as diphenyl carbonate, tetraphenyl orthocarbonate, diphenyl terephthalate, diphenyl oxalate, or cyclohexenyl acetate is added at a step to react with the active terminal group. In addition, the terminal hydroxyl group is reacted with an acid anhydride in advance to convert it into a carboxyl group, and then treated with diazomethane in stage 1'F+ of the molded product or intermediate (for example, polymer powder state), resulting in the active terminal. Although it is possible to reduce the base, the reaction is not practical (
Therefore, there is a need for haste in its use.

In any case, in the present invention, hl- is a group that does not contain a hydrophilic group. It is also undesirable that hydrophilic groups such as urethane and amide groups are introduced as a result of the end-capping process.

In addition, the polyester used is
Measured under the condition of 5℃ (zero degree: f/100CC) 7
It is necessary that the intrinsic viscosity is 0.4 or more. If the intrinsic viscosity is below this range, the product will become a molded film, which will be dull and impractical.

In the present invention, fill 1. The formation of molded products can be carried out by conventionally known methods.

For example, when making a film, the polymer is melt-extruded using an extruder, etc., and the +GL is placed on a casting drum.
R+, and this substantially unstretched film material is stretched in at least one axial direction in one or multiple stages, and subjected to heat treatment or heat relaxation treatment as required. Recent advances in magnetic recording equipment 1-
With a ring rate greater than 1, it became possible to meet the demand by multi-stage high-magnification stretching after studying 41 tons of stretching half-killed for Young's modulus. It has become to.

Even in the present invention, the conventional public 9. n manufacturing means can be applied.

In the present invention, the thickness of the film-like molded product can be selected as required, but it is usually 1 to 500 μmt! , preferably 3-350pm, particularly preferably 10-3001pm
There is 1tn'''C.

In addition, the fineness of the single yarn when making it into a fibrous material is usually 0.1~
It is about 10 deniers, preferably about 1 to 7 deniers.

In addition, instead of woven or knitted fabrics, it is also possible to use a non-woven fabric by a conventionally known method. In short, the polyester of the present invention used as an electrically insulating material has a reduced number of active end groups, regardless of its form.

Next, the present invention will be further explained with reference to Examples.75: This is not intended to detract from the present invention.

Among the examples, Miyako represents Megumi 1 part, and 1-1 polar ocular viscosity is 350. 1.2 f/'100
Lateral pressure was applied on head 1'+. In addition, the carboxyl group was measured using the method of A, Con1x (Makromol, C
Hem, 26 226 (195111)) was used in 4 pots. Water was converted into carboxyl groups by reacting the polymer with cono-phosphoric anhydride in α-methylnaphthalene, which was measured by the method described above, and the difference from the original carboxyl group value was defined as the hydroxyl group.

In addition, the dimensional change due to water absorption is due to the sample (sample length, approx. 2
0 cm) f Dry in a dryer at 150°C for 16 hours, take out the sample, measure its length in the longitudinal direction (machine direction), store it in water at 25°C for 24 hours, take it out and measure the length again. By measuring, the difference in length was divided by the length of the dry sample, expressed as a percentage, and expressed as a water absorption expansion coefficient.

Further, the water absorption rate was calculated based on the '1 pifI stain at that time.

Example 61 In this example, the active terminal group of polyester was layered with diphenyl carboide to make it an electrically insulating material, and the high t (performance) was made lighter.Of course, the present invention The method is not limited to this method.

Dimethyl telecrate 194? fl'* 130 parts of ethylene glycol, 0.095 parts of manganese acetate tetrahydrate, and 0.08 t1 part of antimony trioxide were placed in a rectification column reactor and gradually heated and stirred under a phosphorus atmosphere.

Ester Xt=As a result of the reaction, methanol produced was taken out of the system via a rectification column, and when the collected amount reached a transesterification rate of 98.5%, the temperature inside the system was 235°C.

A distillation condenser was installed except for the rectification column, and the system contained 0.0395 parts of phosphoric acid as a stabilizer and 0.0395 parts of kaolin as a lubricant.
．． Participated in the 03 attack. After heating the system to 280°C and reacting for 130 minutes at -1. The pressure inside the system was reduced each time, and it took about 40 minutes to reach the high y sky of 0.5 cm HgJ-, I. Further, the reaction was continued for 90 minutes. The intrinsic viscosity obtained from this evening's sample was 0.
It was 67. At this point, the system was brought back to normal with 9 parts, and 1-7.5 parts of diphenyl carbonate (3.5 parts per acid component) was added.
5-1 nyl%) was added thereto, stirred for 5 minutes, and brought to a high air pressure of 0.5 wHg or less again while boiling to foam, stirred for 15 minutes, and the polymer was taken out.

The intrinsic viscosity of this polymer was 0.61.

The kernels were made into polymer chips and dried in a hot air dryer at 150°C for 7 hours. The polymer was immediately extruded into a film-forming machine with a complete extruder set at a T-die temperature of 280° C., and taken from the inside onto a water-cooled casting drum. This unstretched film was subjected to continuous biaxial stretching. The stretching phase was 3.8 times in the machine direction at 80°C and 3.5 times in the width direction at 110°C. This was subjected to fixed length heat treatment at 200°C. The obtained film had an I thickness of 25 tfRl and good transparency, and an intrinsic viscosity of 0.54. When the active end groups of this film were measured, it was found that the active terminal groups were 21 tons/ton and the norboxyl groups were 15 tons/ton.
Kun゛ζ. I"l' EQ was prepared with each 1j end-blocked sample, and in comparison with the polyester film produced by Diphenyl Carboy, -T, the changes in insulation breakdown voltage and dimensional changes due to water absorption were shown in the table below.・”I did.

The polyimide film is shown for reference.

Claims (1)

[Claims] In a gas insulating material made of polyester, the polyester has a 4-meter viscosity of 0.4 or more;
The polyester (according to Grade 62 and '1 Shinshaki Insulating Materials) has a total of 1 terminal hydroxyl group and carboxyl group of 90% or less of all terminal groups and does not contain hydrophilic groups.