JPH0730247B2 - Aromatic polyamic acid solution composition - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an aromatic polyamic acid solution composition. More specifically, the present invention relates to aromatic polyamic acid solution compositions containing fine, highly dispersed particles of an inert inorganic material.

[Prior Art and its Problems] The aromatic polyamic acid solution composition is cast on a metal drum or a metal belt, and a part of the solvent is removed by evaporation in a hot-air drying oven to form a self-supporting film. After that, it is also used as a polyimide film forming solution for forming a polyimide film by a method of peeling and holding the periphery with a clip, a pin sheet or the like and introducing it into a high temperature furnace to imidize. Further, as a solution composition for forming a heat-resistant coating film by coating a film-shaped substrate or another substrate using a coating means such as a gravure coater, a reverse roll coater, or a bar coater or another method. Used.

However, since the surface of these polyimide films and polyimide coating films is extremely smooth, slipperiness is poor, runnability in molding processes, poor winding properties, runnability in post-processing processes, handling, etc. There are problems such as poor sex. For this reason, fine inactive inorganic substance particles are contained in the polyamic acid solution to impart irregularities to the surface of the obtained film and film to improve the slipperiness of the surface. Such inert inorganic material particles include titanium dioxide, silicon dioxide, aluminum oxide,
Magnesium oxide, silicon nitride, silicon carbide, etc. are known, but since most of these particles exist in the state of aggregates such as secondary particles and tertiary particles, while using a dispersant, etc., A method is used in which the particles are physically dispersed in a polymerization solvent and fine particles are added.

However, fine inert inorganic particles present in these aggregates are difficult to become primary particles even when subjected to a high degree of dispersion, and the average particle size is small, but the distribution of particle sizes is wide, and coarse particles coexist. Therefore, there is a defect that unevenness imparted to the surface of the polyimide film or the polyimide coating film becomes nonuniform, and coarse particles cause surface defects such as fish eyes.

Further, a polyimide film obtained from a polyamic acid solution produced by a polymerization reaction of a pyromellitic acid component and diaminodiphenyl ether, which is proposed in JP-A-60-127523, has a metal magnetic film such as Co-Cr. When it is vapor-deposited and used as a video tape having a width of 8 mm, when it is run under particularly severe conditions, it cannot be said that it has sufficient running durability and sliding characteristics.

[Object of the Invention] An object of the present invention is to provide an aromatic polyamic acid solution composition containing particles of an inert inorganic substance monodispersed in almost primary particles.

Further, the present invention is particularly excellent in durability, unevenness imparted to the surface is uniform, and has a small number of surface defects. Inert inorganic substance particle-containing aromatic polyamic acid suitable for producing an aromatic polyimide film or an aromatic polyimide coating film. It is intended to provide an acid solution composition.

[Constitution of the invention] The present invention comprises 50 mol% or more (preferably 85 mol% or less).
Aromatic tetracarboxylic acid component consisting of 3,3 ', 4,4'-biphenyltetracarboxylic acid component and 50 mol% or less (preferably 15 mol% or more) of pyromellitic acid component, and relatively large in molar ratio In an amount (preferably 60 to 95 mol%) of p-phenylenediamine and a relatively small amount (preferably 40 to 5).
An aromatic polyamic acid solution obtained by dissolving an aromatic polyamic acid, which is a polymerization reaction product of an aromatic diamine component composed of (mol%) diaminodiphenyl ether, in an organic polar amide solvent and has an average particle size of 40 to 10
Colloidal silica in the range of 00Å and 5% or more of the average particle size of 5% or less of the total number of particles
The aromatic polyamic acid solution composition is characterized by containing 0.001 to 10.0% by weight.

The above aromatic polyamic acid solution composition, for example,
Colloidal silica water-dispersed sol or colloidal silica alcohol-dispersed sol containing colloidal silica having an average particle size in the range of 40 to 1000Å and 1.5 times the average particle size or more and 5% or less of the total number of particles. The colloidal silica amide solvent dispersion sol obtained by substituting water or alcohol with an organic polar amide solvent, is an aromatic tetracarboxylic acid component consisting of a combination of the above-mentioned specific compounds and an aroma consisting of a combination of the above-mentioned specific compounds. A mixture with an organic polar amide-based solvent containing a group diamine component, and then using the method of reacting the aromatic tetracarboxylic acid component and the aromatic diamine component in the resulting mixture to produce an aromatic polyamic acid easily Obtainable.

Alternatively, the colloidal silica amide solvent dispersion sol described above, an aromatic which is a polymerization reaction product of an aromatic dicarboxylic acid component consisting of a combination of the above-mentioned specific compounds and an aromatic tetracarboxylic acid component consisting of a combination of the above-mentioned specific compounds. It can also be easily obtained by a method of mixing an aromatic polyamic acid solution obtained by dissolving a group polyamic acid in an organic polar amide solvent.

Examples of the organic polar amide solvent used in the present invention include:
N-methyl-2-pyrrolidone, dimethylacetamide,
Dimethylformamide can be mentioned.

The aromatic polyamic acid solution composition of the present invention is fine,
In addition, it is characterized by containing colloidal silica having a low content of coarse particles.

The colloidal silica contained in the aromatic polyamic acid solution composition of the present invention is particles having an average particle size of 40 to 1000 Å (preferably 100 to 800 Å) dispersed in almost all primary particles.

Ultrafine particulate anhydrous silica produced by combustion of commonly used purified silicon tetrachloride, or ultrafine particulate titanium dioxide, aluminum oxide or other inorganic fine particles similarly produced by a gas phase method, and dried. The particles present as solids are not suitable for achieving the object of the present invention, as long as the method of adding to the aromatic polyamic acid solution under normal addition conditions is used.

That is, these dry particles are usually in an agglomerated state and crushed and dispersed by a usual dispersing device such as a homomixer, a sand mill, an ultrasonic homogenizer before being added to the aromatic polyamic acid solution or the raw material compound solution of the aromatic polyamic acid. However, the agglomeration cannot be easily solved, and therefore a large number of aggregated agglomerated particles such as secondary particles and tertiary particles having a wide particle size distribution in which primary particles are agglomerated from several to ten or more are introduced into the aromatic polyamic acid solution. Result.

In addition, centrifugation to narrow the particle size distribution of the particles,
Even when the particles are classified by a method such as filtration, it is possible to obtain particles having a sharp particle size distribution defined in the present invention, even if an overcut for removing particles having a certain size or more can be performed.

Therefore, the average particle size used in the present invention is 40 to 1000.
Colloidal silica is preferable for the particles of the inert inorganic substance of Å.

That is, colloidal silica has a narrow particle size distribution in an aqueous dispersion system or an alcohol dispersion system (including an aqueous alcohol dispersion system). Since the particle size distribution does not change much even in the group A polyamic acid solution, colloidal silica can be used particularly advantageously in order to obtain particles having the particle size distribution defined in the present invention.

The colloidal silica used in the present invention has an average particle size in the range of 40 to 1000Å, and particularly preferably an average particle size in the range of 100 to 800Å.

Colloidal silica is generally available as a water-dispersed sol, an alcohol-dispersed sol (eg, a sol dispersed in a lower alcohol such as methanol). Specific examples thereof include various grades sold as Snowtex [manufactured by Nissan Chemical Co., Ltd.] or Cataloid [manufactured by Catalysts & Chemicals Co., Ltd.].

These water-dispersed colloidal silica or alcohol-dispersed colloidal silica is diluted with an organic polar amide solvent and dehydrated or dealcoholized by a method such as vacuum distillation, if necessary, or water-dispersed sol or alcohol-dispersed sol water or An organic polar amide solvent is added while removing alcohol, and water or alcohol is replaced with an organic polar amide solvent before use.

If necessary, they are mechanically dispersed or ultrasonically dispersed, and classified by filtration, centrifugation or the like before use.

The aromatic polyamic acid solution composition of the present invention contains 0.001 to 10.0% by weight, preferably 0.01 to 6.0% by weight, of colloidal silica. When the content of colloidal silica is less than 0.001% by weight, sufficient lubricity cannot be imparted to the aromatic polyimide film or aromatic polyimide coating film formed by using this composition. When the content of colloidal silica is more than 10.0% by weight, colloidal silica is likely to overlap with each other, unevenness to be formed becomes uneven, and mechanical properties of the film and the coating film are impaired.

A specific example of the method for producing the aromatic polyamic acid solution composition of the present invention will be described below by taking the case of using water-dispersed colloidal silica as an example.

That is, first, water-dispersed colloidal silica is added to an organic polar amide-based solvent such as N-methyl-2-pyrrolidone, dimethylacetamide, or dimethylformamide, which is a solvent for polymerization of aromatic polyamic acid, and the dispersion medium is substantially amide-based. Use as a solvent. The silica concentration of this dispersion is preferably 20% by weight or less. Furthermore, if necessary,
The water in this mixed solution is dehydrated using a method such as vacuum distillation. The water content in the organic polar amide-based solvent is selected depending on the solution viscosity, the polyamic acid concentration, the content of particles, etc. required for the application of the aromatic polyamic acid solution composition, but it is usually 5% by volume or less. As another method, while removing water of the water-dispersed colloidal silica by a vacuum distillation method or the like,
A method in which an organic polar amide solvent is added to this may be used.

A liquid in which colloidal silica or the like is dispersed in an organic polar amide solvent is dispersed by a homomixer, an ultrasonic homogenizer or the like, if necessary, and filtered and centrifuged for use.

A raw material monomer such as an aromatic tetracarboxylic acid component or an aromatic diamine component may be directly added to the colloidal silica dispersion liquid obtained as described above and polymerized to obtain an aromatic polyamic acid solution. Alternatively, a low-viscosity solution is obtained by polymerizing the aromatic diamine component and the aromatic tetracarboxylic acid component in a molar ratio of not equal to each other, and the dispersion liquid is added to the solution.
After uniformly stirring, the components lacking may be added and further polymerized to obtain an aromatic polyamic acid solution. Alternatively, it may be produced by adding a colloidal silica dispersion to an aromatic polyamic acid produced by polymerization in advance and stirring.

Thus, the colloidal silica dispersion can be added at any stage of the process for producing the aromatic polyamic acid solution.

In any case, after adding the colloidal silica dispersion and thoroughly stirring and mixing, the colloidal silica is composed of almost primary particles in the aromatic polyamic acid solution, has a sharp particle size distribution, and has a highly dispersed aroma. A group polyamic acid solution composition is obtained.

The particle size of the colloidal silica in the present invention can be measured by the following method. That is, the aromatic polyamic acid composition containing colloidal silica, quickly dry film formation so that the particles do not move due to thermal convection,
Next, the surface of the film was examined using a scanning electron microscope.
Five fields of view were taken at an observation magnification of 10,000 times, the diameter of the particles protruding on the surface was measured, and the number distribution was obtained.From this distribution curve, the average particle diameter and the projections of 1.5 times or more the average particle diameter The ratio and maximum particle size can be determined.

EFFECTS OF THE INVENTION The aromatic polyamic acid solution composition of the present invention has an average particle size of 40 to 1000Å, does not contain a large amount of coarse particles, has a sharp particle size distribution, and is a uniform fine primary particle (single particle). )
It is an aromatic polyamic acid solution obtained from a specific combination of aromatic tetracarboxylic acid components containing a large number of particles in a state and an aromatic diamine component of a specific combination.

The protrusions formed on the surfaces of the aromatic polyimide film and the aromatic polyimide coating film formed by using the aromatic polyamic solution composition of the present invention are fine and uniform, and there are no coarse protrusions due to coarse particles. Therefore, it is possible to obtain an aromatic polyimide film and an aromatic polyimide coating film having a good surface condition and having good slipperiness.

Further, it is possible to eliminate poor running properties, poor winding properties, and poor handling properties in the production of films and coating films and secondary processing steps.

In addition, a base film for magnetic recording media that requires high running durability, fine and uniform surface protrusions, and slipperiness (especially used as an 8 mm wide video tape with a metal magnetic film such as Co-Cr vapor deposited). It can be effectively used for the production of films such as base films used for this purpose) and coating films.

Next, examples and comparative examples of the present invention will be shown.

Example 1 A homomixer was used with 4 parts by weight of dimethylacetamide.
While stirring at 8000 rpm, 1 part by weight of water-dispersed colloidal silica having an average particle size of 150Å and a concentration of 20% by weight was gradually added to obtain colloidal silica dispersed in dimethylacetamide. The water content of this dispersion was 16.1% by volume.

Next, the obtained dispersion liquid was distilled under reduced pressure at 63 ° C. and 25 mmHg, and then dispersed for 30 minutes with an ultrasonic homogenizer having an output of 600 W to obtain dimethylacetamide-dispersed colloidal silica having a concentration of 6.8% by weight and a water content of 1.2% by volume. Obtained.

Separately, 25 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 20 mol% of pyromellitic dianhydride, 15 mol% of diaminodiphenyl ether, and 35 mol% of p-phenylenediamine were converted to dimethylacetamide. After dissolution, the mixture was stirred at 50 ° C. for 5 hours to carry out polymerization to obtain a polyamic acid solution having a viscosity of 8 poise.

The dimethylacetamide-dispersed colloidal silica prepared above was added to this polyamic acid solution in an amount of 1% by weight based on the weight of the polyamic acid at the time of completion of polymerization, and the mixture was stirred and mixed for 1 hour to be uniformly dispersed. Furthermore, 5 mol% of pyromellitic dianhydride was added to this solution and polymerized at 25 ° C. for 2 hours to give a colloidal silica uniformly dispersed concentration of 18% by weight,
An aromatic polyamic acid solution containing colloidal silica having a viscosity of 960 poise was obtained.

The above colloidal silica aromatic polyamic acid solution was spread on a glass plate to a thickness of about 50 μm, and heated using a hot air oven to
It was dried at 0 ° C. for 7 minutes to obtain a self-supporting film, which was peeled off.

The film was held by a metal frame, and hot air at 200 ° C to 380 ° C was supplied to dry and imidize to obtain an aromatic polyimide film having a thickness of 10 µm.

The results of measuring the state of the particles on this film are shown in Table 1.

Example 2 Water-dispersed colloidal silica having an average particle size of 450Å (concentration: 20)
%), And the colloidal silica-containing aromatic polyamic acid solution was produced in the same manner as in Example 1 except that 1.8% by weight of the colloidal silica was added in terms of silica based on the weight of the polyamic acid.

Next, an aromatic polyimide film having a thickness of 10 μm was obtained in the same manner as in Example 1 using the above colloidal silica-containing aromatic polyamic acid solution.

The results of measuring the state of particles on the obtained aromatic polyimide film are shown in Table 1.

[Comparative Example 1] 4% by weight of ultrafine titanium dioxide having a primary particle size of 300Å produced by a gas phase method was added to dimethylacetamide and dispersed using a homomixer at 8000 rpm for 15 minutes, and then this dispersion was 1 μm or more. The particles were classified by filtering with a multilayer filter that cuts 100% of the particles.

Example 1 except that this titanium dioxide dispersion was added in an amount of 1% by weight in terms of titanium dioxide based on the weight of polyamic acid.
A titanium dioxide-containing aromatic polyamic acid solution was obtained in the same manner as in.

Next, using the above titanium dioxide-containing aromatic polyamic acid solution, an aromatic polyimide film having a thickness of 10 μm was obtained in the same manner as in Example 1.

The results of measuring the state of particles on the obtained aromatic polyimide film are shown in Table 1.

[Comparative Example 2] 2% by weight of ultrafine silicon dioxide having a primary particle size of 70Å produced by a gas phase method was added to dimethylacetamide and dispersed using a homomixer at 8000 rpm for 15 minutes, and then output of 600 W or more. It was dispersed for 6 hours using a sonic homogenizer. This dispersion was classified by filtering with a multi-layer structure type filter that cuts 100% of particles of 1 μm or more.

Example 1 except that this silicon dioxide dispersion was added in an amount of 1% by weight in terms of silicon dioxide based on the weight of polyamic acid.
A silicon dioxide-containing aromatic polyamic acid solution was obtained in the same manner as in.

Then, using the above-mentioned silicon dioxide-containing aromatic polyamic acid solution, an aromatic polyimide film having a thickness of 10 μm was obtained in the same manner as in Example 1.

The results of measuring the state of particles on the surface of this film are
Shown in the table.

[Comparative Example 3] 3% by weight of ultrafine aluminum oxide having a primary particle size of 200Å produced by a vapor phase method was added to dimethylacetamide,
The mixture was dispersed at 8000 rpm for 15 minutes using a homomixer. This dispersion was classified by filtering with a multi-layer structure type filter that cuts 100% of particles of 1 μm or more.

An aluminum oxide-containing aromatic polyamic acid solution was obtained in the same manner as in Example 1 except that this aluminum oxide dispersion was added in an amount of 1% by weight in terms of aluminum oxide with respect to the weight of polyamic acid.

Then, using the above-mentioned aluminum oxide-containing aromatic polyamic acid solution, an aromatic polyimide film having a thickness of 10 μm was obtained in the same manner as in Example 1.

The results of measuring the state of particles on the surface of this film are
Shown in the table.

[Measurement of Particle Diameter of Particles in Polyamic Acid Solution] Average particle diameter of inert inorganic material particles and average particle in the inert inorganic material particle-containing aromatic polyamic acid solutions obtained in the above Examples and Comparative Examples. The ratio of coarse particles having a diameter of 1.5 times or more was measured by the following method.

The surface of each of the films obtained in the above Examples and Comparative Examples was photographed in 5 fields of view with a scanning electron microscope at an observation magnification of 20,000 times, the diameter of particles protruding on the surface was measured, and the number distribution thereof was measured. Was obtained and the distribution curve was obtained. Next, from the distribution curve, the average particle size, the range of the particle size, and the ratio of protrusions 1.5 times or more the average particle size (coarse particle ratio, which is the ratio of the number of coarse particles 1.5 times or more the average particle size Substantially match).

The results obtained are shown in Table 1.

[Evaluation of Surface State of Film] The surfaces of the aromatic polyimide films obtained in the above Examples and Comparative Examples were observed with a scanning electron microscope at an observation magnification of 20,000, and Examples 1 and 2 were obtained. Fine irregularities are uniformly dispersed on the surface of the film obtained in 1., large protrusions were hardly seen, but with the fine irregularities on the surface of the films obtained in Comparative Examples 1 to 3. It was observed that there were some large projections caused by coarse particles.

Example 3 A homomixer was used to 4 parts by weight of dimethylacetamide.
While stirring at 00 rpm, 1 part by weight of an aqueous dispersion type colloidal silica having an average particle size of 150 Å and a concentration of 20% by weight was gradually added to obtain colloidal silica dispersed in dimethylacetamide. This dispersion had a water content of 15.8% by volume. Next, this dispersion was distilled under reduced pressure at 15 mmHg and 50 ° C. and then dispersed for 6 hours by an ultrasonic homogenizer having an output of 600 W to obtain dimethylacetamide-dispersed colloidal silica having a concentration of 6.3% by weight and a water content of 0.78% by volume.

3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 30
Mol%, pyromellitic dianhydride 20 mol%, diaminodiphenyl ether 15 mol%, p-phenylenediamine 35
Mol% was dissolved in dimethylacetamide and polymerized by stirring at 25 ° C. for 5 hours to obtain a polyamide solution having a concentration of 18% by weight and a viscosity of 530 poise.

To this polyamic acid solution, 1% by weight of the dimethylacetamide-dispersed colloidal silica prepared above was added in terms of silica based on the weight of the polyamic acid, and the mixture was sufficiently stirred and mixed to uniformly disperse the colloidal silica in the polyamic acid solution for film formation. Got

This solution is extruded from the T die onto the rotating endless metal belt to form a coating film, and then 80 to 13
A hot air of 0 ° C. was supplied to dry the film to form a self-supporting film, which was continuously peeled off.

The film was gripped with a pin tenter and continuously moved in a high-temperature furnace to supply hot air at 200 to 450 ° C. to the surface for drying and imidization to obtain an aromatic polyimide film having a thickness of 12.5 μm.

[Comparative column 4] As aromatic tetracarboxylic acid components, pyromellitic dianhydride (PMDA) 90 mol% and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) 10 mol% As an aromatic diamine component, diaminodiphenyl ether (DADE) 80 mol% and p-phenylenediamine (PPD) 20
An aromatic polyimide film having protrusions formed by filling it with colloidal silica was obtained in the same manner as in Example 3 except that mol% was used.

Comparative Example 5 Same as Example 1 except that 100 mol% of pyromellitic dianhydride (PMDA) was used as the aromatic tetracarboxylic acid component and 100 mol% of diaminodiphenyl ether (DADE) was used as the aromatic diamine component. Then, an aromatic polyimide film in which colloidal silica was filled and projections were formed was obtained.

[Evaluation of Properties of Polyimide Film] Mechanical properties and thermal properties of the polyimide films obtained in Examples 1 to 3 and Comparative Examples 4 to 5 were measured. The measurement results are shown in Table 2.

The units of the evaluation items in Table 2 are as follows.

Tensile strength: kg / mm ² Elongation rate:% Elastic modulus: kg / mm ² Second-order transition temperature: ℃ Thermal decomposition temperature: ℃ Thermal expansion coefficient: cm / cm / ℃ From the above results, a large amount of aromatic dicarboxylic acid component Of pyromellitic dianhydride and a small amount of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, and a combination of a large amount of diaminodiphenyl ether and a small amount of p-phenylenediamine as an aromatic diamine component. When using, the tensile strength is inferior, it is easy to stretch, the elasticity is inferior,
Further, it can be seen that the second-order transition temperature and the thermal decomposition temperature are lowered, while the thermal expansion is increased.

Further, when only pyromellitic dianhydride is used as the aromatic dicarboxylic acid component and only diaminodiphenyl ether is used as the aromatic diamine component, the tensile strength is poor, the stretch is easy, the elasticity is poor, and the second-order transition temperature is low. The thermal decomposition temperature does not change so much, but the thermal expansion increases.

[Evaluation of Polyimide Film as Support for 8 mm Video Tape] After forming a 0.2 μm-thick Co-Cr metal magnetic thin film on the surface of the aromatic polyimide film obtained in each example by vacuum deposition, 8 mm width 8 mm video tape was manufactured by cutting.

About this video tape, sliding, durability (running durability), output (playback output) and DO performed using a commercially available 8 mm video playback device and a dropout counter
Table 3 shows the results of the evaluation test for (dropout).

The test results were displayed based on the following ranks using a commercially available 8 mm video tape (using a polyethylene terephthalate film substrate) as a reference 8 mm video tape and the evaluation value of the reference 8 mm video tape as a reference.

A: Superior to standard 8mm videotape B: Equivalent to standard 8mm videotape C: Inferior to standard 8mm videotape In the description of Table 3 above, C * means that when a metal thin film was formed on a polyimide film by vapor deposition, warpage occurred with the metal thin film side being the inside. In addition, the video tapes produced in Comparative Examples 4 and 5 were found to be elongated when recording and reproducing were repeated.

Claims (1)

[Claims] 1. A relative molar ratio of an aromatic tetracarboxylic acid component composed of 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic acid component and 50 mol% or less of pyromellitic acid component. Aromatic polyamic acid which is a polymerization reaction product of an aromatic diamine component composed of a relatively large amount of p-phenylenediamine and a relatively small amount of diaminodiphenyl ether dissolved in an organic polar amide solvent A polyamic acid solution having an average particle size of 40 to 1000
It is in the Angstrom range and has an average particle size of 1.
An aromatic polyamic acid solution composition comprising 0.001 to 10.0% by weight of colloidal silica in which the number of particles 5 times or more is 5% or less of the total number of particles.