JPH0432105A - Electric insulating film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a novel electrical insulating film, and more specifically, the present invention relates to a novel electrical insulating film, and more specifically, it has improved dielectric breakdown voltage and is widely used in various applications in the electrical and electronic fields. This article relates to electrical insulating films that can be used for various purposes.

[Prior art and invention or problem to be solved] Aromatic ether ketone copolymer is a material with excellent heat resistance, flame retardance, and chemical resistance, and its film is also used as an electrical insulating material in the electrical and electronic fields. In particular, its applications are expected as base films for TABs, heat-resistant flexible printed circuit boards, and dielectric materials for capacitors.

However, this type of etherketone polymer
Generally, when an alkali metal carbonate or alkali metal hydrogen carbonate is used during production, or an alkali metal salt of a diol component is used, some alkali metal salt remains in the produced polymer.

This film with a large amount of residual alkali metal had the disadvantage of having many insulation defects. In particular, when an extremely thin film, such as a dielectric material for a capacitor, is made, there are many places where it will break down when a voltage of 115 or less, which is the average value of dielectric breakdown voltage, is applied, and the actual withstand voltage will be extremely low.

The present invention has been made based on the above circumstances.

An object of the present invention is to provide an electrically insulating film with improved dielectric breakdown voltage.

[Means for solving the above problems] Polyether copolymers are manufactured using an alkali metal salt in an equimolar amount or more than biphenol as a raw material in the manufacturing process. Salts (carbonates) remain in the polyether copolymer at a ratio of about 30 to 50% in the form of chlorides and fluorides (eg, KCI, NaCl).

Usually, these alkali metal salts are removed from the newly produced polyether copolymer by washing with water or alcohol, but the content is not low enough to be used in electrical insulation films.

In our research, we have found that, in particular, when this polyether copolymer is used as a material for forming electrical insulation films,
It has become clear that even a very small amount of residual metal salts may be the cause of insulation failure.

Therefore, the present inventors treated this metal salt with an organic acid.
The present invention was achieved by discovering that when the content is below a certain value, the film can be washed and removed to satisfy practical physical properties as a film for commonly used capacitors and the like.

That is, the invention according to claim 1 for achieving the above object comprises a repeating unit represented by the following formula (I); N (I) and a repeating unit represented by the following formula (■); The composition ratio of the repeating unit represented by the formula (I) [molar ratio=(I)/((I)
+(n))] is 0.15 to (1,40(-l), and the melt viscosity at 400'C is 3.000 to 10
0,000 voids, and the content of alkali metal salts is 5
This is an electrical insulating film formed by molding a polyether copolymer with a concentration of 0 ppm or less.

This will be explained in detail below.

- Polyether copolymer - One of the important points about the polyether copolymer that is the raw material for the electrical insulating film of the present invention is that the polyether copolymer is represented by the formula (1) above. Consisting of a repeating unit and a repeating unit represented by the above formula (II), the content C molar ratio of the repeating degree represented by the above formula (1), (I) / ((I) + (II))] 0
．． 15 to 0.40, and the composition ratio (molar ratio) of the repeating unit represented by formula (n) is 0.85 to 0.60.
It is to be.

The composition ratio of the repeating unit represented by the formula (I) is 0.
If it is less than 15, the glass transition temperature of the polyether copolymer will be low, resulting in a decrease in heat resistance, or the melting point will be high, leading to deterioration in moldability. On the other hand, if it exceeds 0.40, the crystallinity of the polyether polymer will be lost and the heat resistance and solvent resistance will decrease.

In addition, in the polyether copolymer used in the present invention, the melt viscosity (zero shear viscosity) at a temperature of 400°C is 3.00[1 to 1(1(1,0(1(l) voids). is important.

This is because a low molecular weight polyether copolymer having a melt viscosity of less than 3.000 voids cannot achieve sufficient heat resistance and mechanical strength.

Furthermore, if the melt viscosity exceeds 10° or ooo voids, it becomes difficult to form a film.

The polyether copolymer used in the present invention has, for example, a crystal melting point of about 330 to 400°C, has high crystallinity, has a sufficiently high molecular weight, exhibits sufficient heat resistance, and is resistant to solvents. Excellent strength and mechanical strength.
For example, it can be suitably used as a new material in the electrical/electronic equipment field, mechanical field, etc.

Such a polyether copolymer can be produced as follows.

-Production method of polyether copolymer-Polyether copolymer is produced by reacting dihalogenobenzonitrile, 4,4'-biphenol, and an alkali metal compound in the presence of a neutral polar solvent in a specific usage ratio. After that, the reaction product can be produced by carrying out a copolymerization reaction with a specific amount of 4,4''-dihalogenobenzophenone.

Specific examples of the dihalogenobenzonitrile that can be used include 2,6-dihalogenobenzonitrile represented by the following formula: (wherein, X is a halogen atom); .4-dihalogenobenzonitrile and the like.

Among these, preferred are 2.6-dichlorobenzonitrile, 2.6-difluorobenzonitrile, and 2.4-dichlorobenzonitrile.
-dichlorobenzonitrile, 2.4-difluorobenzonitrile, and 2,6-dichlorobenzonitrile is particularly preferred.

The dihalogenobenzonitrile and 4 represented by the following formula;
, 4'-biphenol in the presence of an alkali metal compound and a neutral polar solvent.

The alkali metal compound to be used is
Any substance capable of converting '-biphenol into an alkali metal salt may be used, and there are no particular restrictions, but alkali metal carbonates and alkali metal hydrogen carbonates are preferred.

Examples of the alkali metal carbonates include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate,
Examples include cesium carbonate.

Among these, preferred are sodium carbonate and potassium carbonate.

Examples of the alkali metal hydrogen carbonate include lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate,
Examples include rubidium hydrogen carbonate and cesium hydrogen carbonate.

Among these, preferred are sodium hydrogen carbonate and potassium hydrogen carbonate.

Examples of the neutral polar solvent include N,N-dimethylformamide, N,N-diethylformamide, N,N
-dimethylacetamide, N.

N-diethylacetamide, N,N-cypropylacetamide, N,N-dimethylbenzoic acid amide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-
Isopropyl-2-pyrrolidone, N-isobutyl-2-
Pyrrolidone, Nn-propyl-2-pyrrolidone, Nn
-butyl-2-pyrrolidone, N-cyclohexyl-2-
Pyrrolidone, N-methyl-3-methyl-2-pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-)-dimethyl-2-pyrrolidone, N-
Methyl-2-piperidone, N-ethyl-2-piperidone, N-isopropyl-2-piperitone, N-methyl-6
-Methyl-2-piperidone, N-methyl-3-ethylpiperitone, dimethyl sulfoxide, diethyl sulfoxide, l-methyl-1-oxosulfolane, l-ethyl-
Examples include 1-oxosulfolane, l-phenyl-1-oxosulfolane, N,N'-dimethylimidasilidinone, diphenylsulfone, and the like.

An example of the production method includes a reaction product obtained by reacting the dihalogenobenzonitrile with the 4.4'-biphenol in the presence of the alkali metal compound and the neutral polar solvent; React with 4'-dihalogenobenzophenone.

The 4,4'-dihalogenobenzophenone to be subjected to the reaction is a compound represented by the following formula; -difluorobenzophenone and 4.4''-dichlorobenzophenone are particularly preferably used.

The molar ratio of the total amount of dihalogenobenzonitrile and 4,4'-dihalogenobenzophenone to the amount of 4,4'-biphenol used is usually 0.98 to 1.02.
, preferably 1.00 to 1. It is Ol. The molar ratio of the alkali metal compound is usually 03 to 2.50, preferably 1.05 to 1.25.

There is no particular restriction on the amount of the neutral polar solvent used, but it is usually the same amount as the dihalogenobenzonitrile and 4.
A total of 10 (per 1 part by weight) of 4'-biphenol and the alkali metal compound is selected in the range of 200 to 2.000 parts by weight.

To obtain the polyether copolymer, for example, the dihalogenobenzonitrile, the 4,4°-biphenol, and the alkali metal compound are added simultaneously to the neutral polar solvent.

After the dihalogenobenzonitrile and the 4.41 biphenol are reacted, the 4.4'-
Add dihalogenobenzophenone, usually 150-3
The series of reactions is carried out at a temperature of 80°C, preferably in the range of 180-330°C. If the reaction temperature is less than 150°C, the reaction rate is too slow to be practical;
Exceeding this may lead to side reactions.

In addition, the reaction time of this series of reactions is usually 0.1 to 1
0 hours, preferably 0.5 hours to 5 hours.

After completion of the reaction, the polyether copolymer is separated and purified from the resulting neutral polar solvent solution containing the polyether copolymer according to a known method to obtain a polyether copolymer. Something comes up.

In addition, the polyether copolymer used in the present invention is
It can also be obtained by simultaneously adding dihalogenobenzonitrile, biphenol, alkali metal salt, and dihalogenobenzophenone to a neutral polar solvent.

The polyether copolymer used in the present invention is 4
Melt viscosity at 00°C is 3,000 to 100,000
It has a crystalline melting point of 330 to 400°C.

An important point in the electrical insulating film of the present invention is that the content of alkali metal salt contained in the polyether copolymer, which is the raw material for the film, is 50 pp- or less. be.

The content of alkali metal salt in the polyether copolymer after completion of polymerization can be determined by washing the polyether copolymer with an acidic aqueous solution containing an organic acid or an inorganic acid and adjusted to pH 3.5 or less. By doing so, it can be reduced.

Examples of the organic acid include formic acid and acetic acid.

Examples include monocarboxylic acids such as monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, and propionic acid, and dicarboxylic acids such as oxalic acid and malonic acid. Among these, dicarboxylic acids such as oxalic acid are preferred, and oxalic acid is particularly preferred. Note that these organic acids can be used alone or in combination of two or more.

Examples of the inorganic acid include hydrochloric acid, sulfuric acid, and phosphoric acid. Among these, hydrochloric acid is preferred.

Solutions containing these acids have a pH of 1. It is best to adjust the concentration or determine the type of acid so that it is below s.

The time for washing the polyether copolymer with the acidic aqueous solution is sufficient to reduce the alkali metal salt content in the polyether copolymer to 50 pp or less. In addition,
In order to promote the desalination effect by washing, the mixture of the acidic aqueous solution and the polyether copolymer may be heated during washing.

After washing with an acidic aqueous solution, it is recommended that the polyether copolymer be thoroughly washed with pure water, ion exchange water, distilled water, etc. in order to remove the acid from the polyether copolymer.

Next, for the electrical insulation film of the present invention, the sufficiently desalted polyether copolymer may be used as is, or the desalted polyether copolymer and an inorganic filler may be used. Mixed polyether copolymer resin compositions can also be used.

The polyether copolymer resin composition includes the polyether copolymer and an inorganic filler.

It is produced by blending an inorganic filler into a polyether copolymer so that its content is 10 to 50% by weight, preferably 15 to 40% by weight.

When the amount of the inorganic filler is within the above range, the coefficient of thermal expansion of the electrically insulating film can be reduced.

Examples of the inorganic filler include carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and magnesium sulfate, sulfites such as calcium sulfite, talc, clay, mica, asbestos, glass fiber, and glass. peas, calcium silicate, montmorillonite, bentonite, and other silicates, silicon dioxide, alumina, metal powders such as iron, zinc, and aluminum, ceramics such as silicon carbide, silicon nitride, and their whiskers, carbon black, graphite, and carbon. Preferable materials in the present invention include, for example, calcium carbonate, silicon dioxide, alumina, clay (kaolin, bentonite, clay, etc.), talc, metal oxides (MgO, ZnO1Tie, etc.), etc. .

The inorganic filler may be in the form of a single particle, a plate, or a fiber, but in this invention, the particle size is 5JL.
m or less, and preferably a finer one is used.

These inorganic fillers may be used alone or in combination of two or more.

The polyether copolymer resin composition is prepared by adding an appropriately selected inorganic filler to a polyether copolymer powder obtained by the above-mentioned polyether copolymer manufacturing method in a proportion of 10 to 50% by weight. After mixing and blending,
It can be obtained by kneading in an extruder and pelletizing.

Further, a polyether copolymer composition can also be obtained by employing a method of producing a polyether copolymer in the presence of an inorganic filler.

-Method for producing electrically insulating film- The electrically insulating film of the present invention is produced by using the polyether copolymer obtained as described above, in which the content of alkali metal salt in the polymer is reduced to 50 pp or less, or It is obtained by forming a polyether copolymer resin composition into a film.

Formation into a film is performed using a conventional method such as an extrusion molding method or a press molding method at a temperature of 10 to 100 degrees higher than the crystal melting point, preferably 30 to 709 C higher than the crystal melting point, and then rapidly cooled. A non-grade film with good transparency can be obtained.

For example, the polyether copolymer or the polyether copolymer resin composition is supplied to an extruder, the resin temperature is set at 350 to 450°C, and the molten state is extruded through a slit-shaped die, followed by cooling and solidification. By this,
An unstretched, non-quality film of the polyether copolymer or polyether copolymer resin composition can be produced.

Or press temperature 350-450 using a heat press machine
By producing a press film at .degree. C., it is possible to obtain an unstretched, unstretched film of a polyether copolymer or a polyether copolymer resin composition.

Then, the electrical insulating film of the present invention can be produced by uniaxially or biaxially stretching and orienting these unstretched films.

The stretching method may be either two-wheel simultaneous or one-axis sequential.

The stretching temperature is a temperature between the glass transition temperature and the crystal melting point,
For example, it is carried out at 180 to 250°C.

The stretching ratio is preferably 1.2 to 3 times, particularly 1.
It is preferable that it is 3 to 2.5 times.

If the stretching ratio is less than 1.2 times, a sufficient stretching effect (improving effect on film properties such as tensile strength and tensile modulus) may not be achieved. The effect may not improve further.

Furthermore, by heat-treating the film before or after stretching, it is possible to obtain a heat-treated film with significantly improved heat resistance.

Heat treatment of the film is carried out by heat treatment at a temperature between its crystallization temperature and crystal melting point, resulting in a crystallized film.

Regardless of the stretching, the heat treatment is performed under tension, and the crystallization temperature is higher than the temperature at which the polymer amorphized by the film formation or crystallized by heat treatment (temperature elevation) and lower than the crystal melting point. For example, it is carried out at 190 to 370°C.

As a preferred example, the stretched film is fixed with a metal frame or the like, and heat-treated under tension for 1 to 600 seconds while heating to 190 to 370°C.

There are no particular restrictions on the heating method, and various means can be employed.

Furthermore, the heat-treated film obtained by this heat treatment is
A reheat-treated film can be produced by performing reheat treatment again at a temperature near the heat treatment temperature.

This reheat treatment is carried out under tension or without tension as necessary, and is carried out at a temperature between the glass transition temperature of the polyether copolymer and the polyether copolymer resin composition and the heat treatment temperature. Good.

By performing this reheat treatment, the heat shrinkage rate of the heat-treated film is reduced, making it possible to obtain a film with excellent dimensional stability.

The film thus obtained can be used as an electrical insulating film (1) in the electronics field as a base film for flexible printed circuit boards, a backing material for flexible printed circuit boards, an electrode plate for membranes, a backing material for membranes, a base film for transparent electrodes, Can be used for liquid crystal film cells, IC carrier tapes (TAB base films), optical cards, perpendicular magnetization base films, etc. (2) In the electrical and thermal insulation fields, sheet heating element bases and surface cover films. , insulation tape (motor,
Generators, transformers), capacitors, wire coatings, shielding plates for microwave ovens and other heat equipment, speaker diaphragms, lighting equipment covers, instrument display panels, base films for thermal transfer recording media, base films for magnetic recording media, etc. It can be used for.

[Examples] Next, the present invention will be described in more detail based on Examples.

(Example 1) 1,548 g of 2,6-cyclopenzonitrile was placed in a reactor with an internal volume of 200 L equipped with a Dean-Starck trap filled with toluene, a stirring device, and an argon gas blowing tube.
g (9 mol), 4.4°-biphenol 5,580
g (30 mol), potassium carbonate 4.561 g (
33 mol) and 50 moles of N-methyl-2-pyrrolidone were added, and the temperature was raised from room temperature to 195°C over 1 hour while blowing argon gas.

After raising the temperature, a small amount of toluene was added and the produced water was removed by azeotropy.

Next, after carrying out a reaction at a temperature of 195°C for 30 minutes, 4,4°-difluoropenzophenone 4.582
g (21 mol) to N-methyl-2-pyrrolidone 70
! 1 of the solution was added, and the reaction was further carried out for 1 hour.

After the reaction was completed, the product was pulverized using a blender (manufactured by Warning Co., Ltd.) and poured into ion-exchanged water.

After that, it was washed 3 times with warm ion-exchanged water, once with Shuu Water Resistant adjusted to pH 3, and 4 times with ion-exchanged water, and then dried. ) was obtained.

When the properties of this copolymer were measured, it was found that the temperature of 40
Melt viscosity at 0°C (zero shear viscosity) is 13.000
It has a glass transition temperature of 182℃ and a crystal melting point of 37.
The starting temperature of thermal decomposition was 562°C (5% weight loss in air).

This copolymer consists of repeating units represented by the above formulas (I) and (U), and has a molar composition ratio of [(I)/((I)+
(II)) ] or 0.3.

Next, this polyether copolymer was supplied to a twin-screw extrusion machine (PCM-30, manufactured by Toshiken Tekko Co., Ltd.) and extruded at a temperature of 390°C to form pellets.

Using this pellet, extrusion molding was carried out using a ■-die to obtain a film having a width of 25 cm.

Next, this film was subjected to biaxial stretching (manufactured by Toyo Seiki Seisakusho) at a stretching speed of t, ooo%/min, at 188°C, and stretched three times in both the length and width directions, and at 250″C under the foot length.
Heat treatment was performed for 30 seconds to obtain a biaxially oriented film with a thickness of 8 pm.

Dielectric breakdown strength of this film (ASTM D149
) and the metal element content were measured.

The results are shown in Table 1.

(Comparative Example 1) A film was obtained in the same manner as in Example 1, except that after producing the polymer, only water washing was performed and no water-resistant washing was performed.

The dielectric breakdown strength and metal element content of this film were measured.

The results are shown in Table 1.

(Example 2) A film was prepared in the same manner as in Example 1, except that washing with hydrochloric acid (pH 2) was used in place of washing with hydrochloric acid after polymer production, and dielectric breakdown strength and Metal element content was measured.

The results are shown in Table 1.

Table 1 [Effects of the Invention] According to the present invention, it is possible to provide an electrical insulating film with improved dielectric breakdown voltage.

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Claims (1)

[Claims] (1) The following formula (I); ▲There are mathematical formulas, chemical formulas, tables, etc.▼ The repeating unit represented by (I) and the following formula (II); ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Represented by (II) The composition ratio of the repeating units represented by the above formula (I) [molar ratio: (I)/{(
I)+(II)}] is 0.15 to 0.40 mol, and the melt viscosity at 400°C is 3.000 to 10
0,000 poise, and the content of alkali metal salt is 5
An electrical insulating film formed by molding a polyether copolymer with a concentration of 0 ppm or less.