JPH0443019A - Manufacture of heat-resistant film - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant film having excellent surface smoothness, heat resistance, and dimensional stability at a high temperature by primarily orienting and secondarily orienting a film manufactured by thermoforming a polyether copolymer resin, which has a specific composition and melting viscosity of which has a specific value, under specific conditions and thermally fixing the film. CONSTITUTION:A film manufactured by thermoforming a polyether copolymer resin, which is composed of repeated units shown in formulae I, II and in which a composition ratio [a mol ratio: I/(I+II)] at the repeated unit shown in formula I is 0.15-0.40mol while melting viscosity at 400 deg.C is 3,000-100,000 poises, is primarily oriented under the conditions of a temperature of 170-250 deg.C, a draw ratio of (1.5-4) fold and the speed of orientation of 200-10,000%/min, and secondarily oriented in the direction orthogonal in the direction of orientation of primary orientation under the conditions of a temperature of 170-270 deg.C, a draw ratio of (1.5-4) fold and the speed of orientation of 200-10,000%/min, and thermally fixed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a heat-resistant film, and more specifically, to various applications in the electronics field, electrical and thermal insulation field, and other general industrial fields. This invention relates to a method for producing a heat-resistant film that can be used widely.

[Prior art and the problem to be solved by the invention] In recent years, various resin films with excellent heat resistance and mechanical strength have been developed, and these are used as electrical insulation materials and heat-resistant flexible printed circuits in the electrical and electronic fields. Like the board, etc.
It is used for a wide range of purposes as a material for parts of equipment and machinery.

Therefore, as the range of applications for resin films expands,
Even better properties than before, i.e. heat resistance, flame retardancy,
Resin films with properties such as mechanical strength are increasingly required.

Examples of currently used resin films include:
Films made of polyimide and the like have major disadvantages such as difficulty in extrusion molding and high prices. Therefore, attempts have been made to produce heat-resistant films using thermoplastic resins.

However, even polyetheretherketone, which is said to have the best heat resistance and chemical resistance, has the disadvantage that the formed film has poor surface smoothness due to thinning by stretching.

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

An object of the present invention is to provide a heat-resistant film that has excellent surface smoothness, heat resistance, and dimensional stability at high temperatures.

[Means for solving the above problem] The configuration of the present invention for solving the above problem is expressed by the following formula (I)
: Consisting of a repeating unit represented by the following formula (II) and a repeating unit represented by the following formula (II), the composition ratio [molar ratio] of the repeating unit represented by the formula (I).

(I)/((I)+(n))] or 0.15 to 0.4
A film obtained by thermoforming a polyether copolymer resin having a melt viscosity of 0 mole and a melt viscosity of I at 400°C and a void of 000 to 100,000 is heated at a temperature of 170 to 250°C and a stretching ratio of 1.5 to 4. Production of a heat-resistant film characterized by first stretching at a stretching speed of 200 to 10,000%/min, then second stretching in a direction perpendicular to the stretching direction, and then heat setting. It's a method.

The present invention will be explained in detail below.

-Polyether copolymer- One of the important points about the polyether copolymer that is the raw material for the heat-resistant film of the present invention is that the polyether copolymer is It consists of a repeating unit and a repeating unit represented by the above formula (II), and the content ratio of the repeating unit represented by the above formula (I) [molar ratio, (I)/< (I) + (II))] The composition ratio (molar ratio) of the repeating unit represented by formula (I1) is in the range of 0.15 to 0.40, and the composition ratio (molar ratio) of the repeating unit represented by formula (I1) is in the range of 0.85 to 0.
It is 60 years old.

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, and 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.

Further, in the polyether copolymer used in the present invention, it is important that the melt viscosity (zero shear viscosity) at a temperature of 400°C is 3,000 to 100,000 voids.

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.

In addition, when the melt viscosity exceeds 100,000 voids, the moldability such as forming into a film deteriorates.

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 properties 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, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4
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 that can convert biphenol into an alkali metal salt may be used, and there are no particular limitations, 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, and 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-inphthyl-2
-pyrrolidone, N-n-propyl-2-pyrrolidone, N
-n-phthyl-2-pyrrolidone, N-cyclohexyl-
2-pyrrolidone, N-methyl-3-methyl-2-pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-trimethyl-2-birosotone, N-
Methyl-2-piperitone, N-ethyl-2-piperitone, N-impropyl-2-piperitone, N-methyl-6
-Methyl-2-piperitone, N-methyl-3-ethylpiperitone, dimethyl sulfoxide, diethyl sulfoxide, 1-methyl-1-oxosulfolane, l-ethyl-
Examples include 1-oxosulfolane, l-phenyl-1-oxosulfolane, N,N'-dimethylimidazolidinone, diphenylsulfone, and the like.

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

The 4,4'-dihalogenobenzophenone used has the following formula.

(X has the same meaning as above.) In the present invention, 4.4''-difluorobenzophenone and 4.4゜dichlorobenzophenone are particularly preferably used. I'll come.

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 to 4,4°-biphenol is
Usually 1.03 to 2.50, preferably 1.05 to 1
．． It is 25.

Is there any particular restriction on the amount of the neutral polar solvent used? Usually, the amount of the dihalogenobenzonitrile and the 4.
The amount is selected from 200 to 2.000 parts by weight per 100 parts by weight of the 4°-biphenol and the alkali metal compound.

In order to obtain a polyneedle copolymer, for example, the dihalogenobenzonitrile, the 4.4°-biphenol, and the alkali metal compound are simultaneously added to the neutral polar solvent. After reacting the halogenobenzonitrile with the 4,4′ biphenol,
Furthermore, the above 4.4'-dihalogenobenzophenone is added.
A series of reactions are carried out at temperatures in the range of 0°C.

If the reaction temperature is less than 150°C, the reaction rate is too slow to be practical, and if it exceeds 380°C, side reactions may occur.

In addition, the reaction time of this series of reactions is usually 0.1 to 10
The time is preferably 5 to 5 hours.

After the reaction is complete, the polyether copolymer is separated and purified from the resulting neutral polar solvent solution containing the polyether copolymer according to a known method. You can get it.

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: 3,000 to 100,00
It has 0 voids and its crystal melting point is 330-400°C.

In the heat-resistant film of the present invention, the content of the alkali metal salt contained in the polyether copolymer, which is the raw material of the film, is 50% or less.
It is desirable that it be less than ppm.

This is because if a polyether copolymer contains more than 50 ppm of an alkali metal salt, if a heat-resistant film formed from such a polyether copolymer is used in a magnetic recording medium, for example, This is because the magnetic head may corrode due to long-term use.

In order to reduce the alkali metal salts in the polyether copolymer after polymerization, the polyether copolymer is treated with an acidic aqueous solution containing an organic acid or an inorganic acid and whose pH is adjusted to 3.5 or less. Should I wash it?

Examples of the organic acids include monocarboxylic acids such as formic acid, acetic acid 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. Incidentally, these organic acids can be used singly or in combination of two or more.

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

For solutions containing these acids, the concentration may be adjusted so that the pH is 3.5 or less, or the type of acid may be determined.

The time for washing the polyether copolymer with the acidic aqueous solution is sufficient to reduce the content of alkali metal salt in the polyether copolymer to 5i1 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 or heated under pressure during washing.

After washing with an acidic aqueous solution, it is recommended to thoroughly wash with pure water, ion-exchanged water, distilled water, etc. in order to remove the acid from the polyether copolymer.

Next, the heat-resistant film of the present invention can be formed from the polyether copolymer that has been sufficiently desalted, or it can be formed from the polyether copolymer that has been desalted and an inorganic filler. It can also be formed from a mixed polyether copolymer resin composition.

The polyether copolymer resin composition contains the polyether copolymer and the inorganic filler, and the content of the inorganic filler is less than 10% by weight, preferably less than 10% by weight, based on the polyether copolymer. By setting o, oos to 5% by weight, the slipperiness of the film surface is improved, and by setting the content to 10 to 50% by weight, preferably 15 to 40% by weight, a film with a small coefficient of thermal expansion can be obtained. You can get it.

Examples of the inorganic filler include carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and magnesium sulfate, sulfite salts such as calcium sulfite, talc, clay, eyelid, asbestos, Glass powder, glass doze, silicates such as calcium silicate, montmorillonite, bentonite, silicon dioxide, alumina, metal powders such as iron, zinc, aluminum, ceramics such as silicon carbide, silicon nitride, and their whiskers, Examples include carbon fluff, graphite, and carbon fiber. Preferred in the present invention are, for example, calcium carbonate, silicon dioxide,
Alumina, clay (kaolin, bentonite, white clay, etc.),
These include talc, metal oxides (MgO, ZnO, Ti1t), etc.

The inorganic filler may be in the form of particles, plates, or fibers; in this invention, the inorganic filler may have a particle size of 5 pm.
It is sufficient if it is less than that, 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 the polyether copolymer balater obtained by the above-mentioned polyether copolymer manufacturing method in a proportion of up to 50% by weight. After mixing and friending, the mixture is kneaded in an extruder and made into pellets.

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

- Method of forming a polyether copolymer into a film - The heat-resistant film of the present invention is produced by preparing the polyether copolymer obtained as described above, preferably containing an alkali metal salt in the polymer. Preferably, the polyether copolymer or polyether copolymer resin composition has a content of alkali metal salt in the polymer reduced to 50 ppm or less. It can be obtained by forming a film from the combined resin composition.

Film formation is performed using a conventional method such as extrusion molding at a temperature 10 to 100°C higher than the crystal melting point, preferably,
By performing rapid cooling at a temperature 30 to 70°C higher than the crystal melting point, a non-quality film with good transparency can be obtained.

For example, the Botether copolymer or the polyether copolymer resin composition is supplied to an extruder, the resin temperature is set at 350 to 450°C, the molten state is extruded through a slit-shaped tie, and the mixture is cooled and solidified. Accordingly, an unstretched, non-quality film of the polyether copolymer or polyether copolymer resin composition can be produced.

- Stretching and forming of film - Next, these unstretched films are subjected to secondary and secondary stretching according to the method of the present invention, that is, an oriented film is produced by sequential two-wheel stretching.

■Second Stretching As the first stretching, the unstretched film is stretched longitudinally, for example.
- Making an axially oriented film.

The stretching temperature is a temperature between the glass transition temperature and the crystal melting point,
For example, at 170-250°C, especially at 175-22°C.
0°C is preferable.

If the stretching temperature is less than 170°C, it will not be possible to stretch uniformly, and the accuracy of the thickness will decrease. Further, at a temperature of 250°C or higher, crystallization proceeds faster than stretching, resulting in a higher yield point stress and further opacity of the film due to the formation of spherulites.

The stretching speed is preferably 200 to 10,000%/min, particularly 500 to 6,000%/min.

At stretching speeds below 200%/min, the orientation is relaxed and
A good degree of orientation may or may not be obtained.

The stretching ratio is preferably 1.5 to 4 times.

If the stretching ratio is less than 1.5 times, a sufficient stretching effect (improving effect on film properties such as tensile strength and tensile modulus) may not be achieved, and an increase in the strength of the film after subsequent transverse stretching cannot be expected. Furthermore, if the film is stretched more than 4 times, the film is likely to break during the subsequent transverse stretching process, making stable production impossible.

(2) Secondary Stretching After the above-mentioned secondary stretching, stretching is further performed in a direction perpendicular to the stretching direction of the secondary stretching to produce a biaxially oriented film.

The stretching temperature is preferably within a range with the lower limit being the temperature at the second stretching and the upper limit being 20° C. higher. In particular, it is preferable to perform the second stretching at the same temperature as the second stretching, and to stretch the film at a temperature slightly higher than the temperature during the second stretching, since the molecular chains of the film are oriented by the second stretching. This is because they are motivated to exercise.

The stretching speed is preferably within the same range as the speed during the next stretching,
In particular, it is preferable that the stretching speed be the same as that for the second stretching.

The stretching ratio is preferably 1.5 to 4 times as in the second stretching, and particularly preferably the same as the stretching ratio during the second stretching.

By sequentially biaxially stretching an unstretched film as described above, a good biaxially oriented film with excellent surface smoothness can be obtained.

Furthermore, by heat-treating the film obtained by the above 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.

The heat treatment is performed under tension, and the temperature is set at a temperature higher than the crystallization temperature, that is, the temperature at which the above-mentioned film-formed and amorphous polymer is crystallized by heat treatment (temperature elevation), and lower than the crystal melting point, for example, 190 to 370'C. I will do it.

A preferred example is to fix the stretched film to a metal frame or the like, heat it under tension to 190 to 370''C, and then heat treat it for 1 to 600 seconds.

There are no particular restrictions on the heating method, and various means may 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 around the heat treatment temperature.

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

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 heat-set biaxially oriented film of the polyether copolymer produced as described above is a heat-resistant film with excellent surface smoothness and excellent dimensional stability at high temperatures.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention.

(Example 1) A polyether copolymer was produced as described below, and then formed into a film to produce a heat-resistant film.

-Production method of polyether copolymer- 1,548 ml of 2,6-cyclopenzonitrile was added to a reactor with an internal volume of 200 mm, which was 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 molar of N-methylpyrrolidone, and while blowing in argon gas, warmed to room temperature over 1 hour.
The temperature was raised to 5°C.

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

Then, after reacting for 30 minutes at a temperature of 195°C, 4.582 g of 4,4°-difluorobenzophenone
A solution of (21 mol) dissolved in 70 ml of N-methylpyrrolidone 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 Warninck), washed with water and methanol in that order, and then dried to obtain 10.0 kg of white powder (yield: 98%).

When the properties of this powdered product were measured, the melt viscosity (zero shear viscosity) at a temperature of 400°C was 13,
It had a glass transition temperature of 185°C, a crystal melting point of 379°C, a crystallization temperature of 250°C, and a thermal decomposition initiation temperature of 562°C (5% weight loss in air).

Further, according to IR spectrum analysis, this powdered product was found to be a polyether copolymer having the following repeating units.

N (I) Core (II) (I) / ((I) + (II)) = 0.3 - Production of polyether copolymer film (non-quality film) - Obtained polyether copolymer The combined product was extruded at 390° C. using a twin-screw extruder (manufactured by Toshiken Tekko Co., Ltd.; PCM-:10), and then formed into pellets.

Using this pellet, a film having a diameter of 25 cm was formed using a tie.

-Production of biaxially oriented film of polyether copolymer- The non-quality film obtained as described above was sequentially biaxially stretched under the stretching conditions shown in Table 1.

Next, the obtained stretched film was heated at 300°C under tension.
After heat treatment for 13 minutes, heat treatment was performed again at 300° C. for 13 minutes under no tension to heat set, thereby producing a heat-set biaxially oriented film.

Next, in order to examine the surface smoothness of the obtained sequentially biaxially stretched film, the surface roughness of the non-quality film was measured.

The surface roughness was measured according to the center line average roughness measurement method of JIS BO601.

Stylus type surface roughness meter (SURF (:OM) manufactured by Tokyo Seimitsu Co., Ltd.
:IB), needle radius 2ALm, load 0.07
A chart (film surface roughness curve) was drawn under the conditions of g.

From the film surface roughness curve, extract a part (measured length to reference length) in the direction of its center line, take the center line of this extracted part as the X axis, take the direction of vertical magnification as the Y axis, and make the roughness curve Y = When expressed as f (x), the value Ra (p■) given by the following formula was defined as the flatness of the film surface.

Ra-(I/L) f'off(x)l dxIn the present invention, 10 pieces are measured with a reference length of 0.025 mm, and Ra
Ra was expressed as the average value of the remaining 7 items after removing 3 items from the highest values.

The results are shown in Table 1.

(Examples 2 and 3) Examples 2 and 3 were conducted in the same manner as in Example 1, except that sequential biaxial stretching was carried out under the stretching conditions shown in Table 1.

The results are shown in Table 1.

(Comparative Examples 1.2 and 3) Example 1 except that the non-quality film obtained in Example 1 was subjected to simultaneous two-wheel stretching under the conditions shown in Table 1.
I did the same thing.

The results are shown in Table 1.

(This page, the following margins) (i! value) In Examples 1 to 3 and Comparative Examples 1 to 3, the polyether copolymer films formed by the sequential two-wheel stretching of the present invention had a flatness of the film surface. It was confirmed that the method of the present invention can produce a heat-resistant film with excellent surface smoothness.

[Effects of the invention] According to the present invention, by sequentially biaxially stretching the polyether copolymer, which is a raw material for a heat-resistant film, the excellent heat resistance and mechanical strength of the polyether copolymer are impaired. Therefore, it is possible to obtain a biaxially oriented film with excellent surface smoothness, and it is possible to provide an industrially useful heat-resistant film.

Claims (1)

[Claims] The following formula (I); ▲There are mathematical formulas, chemical formulas, tables, etc.▼The repeating unit represented by (I) and the following formula (II); ▲Mathematical formula,
There are chemical formulas, tables, etc. ▼ (II) It consists of repeating units represented by the formula (I), and 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
A film thermoformed from a 0,000 poise polyether copolymer resin is subjected to a primary process at a temperature of 170 to 250°C, a stretching ratio of 1.5 to 4 times, and a stretching speed of 200 to 10,000%/min. Stretching, and then second stretching in a direction perpendicular to the stretching direction of the first stretching at a temperature of 170 to 270°C, a stretching ratio of 1.5 to 4 times, and a stretching speed of 200 to 10,000%/min. A method for producing a heat-resistant film, which comprises heat-setting the film.