JPH10204188A - Heat-resistant synthetic resin film having improved slipperiness and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant synthetic film exhibiting desirable mechanical properties, being capable of being used as a base film reduced in thickness and having very smooth surface roughness required in various uses without detriment to the slipperiness in handling during the production process or in service as a product. SOLUTION: This film is one made from a heat-resistant resin, having an average thickness of 2-8μm, containing 0.005-1.0wt.% inert microparticles having a mean particle diameter of 5-150nm and an average degree of agglomeration of 1-100 and satisfying the requirements: at least either of the surfaces has a center average surface roughness (SRa) of 0.1-10nm when observed from the resolving power of an optical surface roughness meter, the maximum protrusion height (Zmax) is 5-100nm when measured with an interatomic power microscope, at least either of the surfaces has a gentle undulation approximate to a two-dimensional sinusoid in the direction of surface, the center line depth of this undulation is 0.1-1.5μm, the wavelength of the undulation is 0.05-5mm, and the coefficient of dynamic friction is 0.5 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin heat-resistant base film having excellent mechanical properties, and more particularly, to an extremely smooth base film required for a printing ink ribbon or a magnetic tape. The present invention relates to a heat-resistant base film having both a surface and an excellent slip property required for use as a production process or a product.

[0002]

2. Description of the Related Art Conventionally, it has been known that if the surface of a film is too smooth, the film loses its slipperiness and its handleability deteriorates, such as generation of wrinkles during production and use. It is known to produce a film by adding fine particles such as inorganic particles as a lubricant.

On the other hand, for example, it has been pointed out that the surface property of a base film of a magnetic tape is important for the properties of the magnetic tape. In particular, in order to increase the capacity of the magnetic tape per cassette, use a thin film of high elastic modulus such as aramid as the base film to reduce the tape thickness and increase the tape length per cassette, and shorten the signal wavelength. In addition, the use of thinner magnetic powder, thinner coating of magnetic powder, and the use of metal thin film type magnetic tape on which metal has been deposited or sputtered have been implemented, and the base film surface Is required to be smooth.

Conventionally, in order to meet these demands, for example, in Japanese Patent Application Laid-Open No. 60-127523, the height of individual fine projections is not accurate, but the height measured by a stylus type surface roughness meter. Fine protrusions of 3 to 50 nm are 1
An aramid film of 0 ⁴ to 10 ⁸ particles / mm ² has been proposed, and Japanese Patent Application Laid-Open No. 4-149452 discloses an aramid film in which lubricant particles added for adjusting fine projections on the surface are made into a specific aggregated state. Has been proposed. In JP-A-8-55328, fine protrusions having a height of 50 nm or more measured by an electron microscope are 2 × 10 ³ to 2 × 10 ^7.
A magnetic tape using an aramid film of pieces / mm ² has been proposed. The invention of Japanese Patent Application Laid-Open No. 60-127523 discloses a magnetic tape of a type in which a metal thin film whose surface shape is directly reflected on the surface of the magnetic layer is formed on the base film, as compared with a type in which a magnetic layer is coated. It is intended for use.

[0005] In any of these proposals, at the recording density of video recording at that time, the fine projections having the above height were sufficient, but in recent data recording applications, digital signals are recorded and the recording wavelength is reduced. At the height of the protrusions, the head is lifted from the surface of the magnetic tape by that much, so-called spacing loss is increased, and there has been a problem that a signal writing / reading error occurs. .

It is natural to think that one side of the film is made extremely smooth and the other side is made rough to achieve smoothness and slipperiness at the same time.
No. 4, JP-A-3-119512 and the like. Japanese Patent Application Laid-Open No. Hei 8-235568 proposes that a certain amount of coarse protrusions having a height of 700 nm or more be present on the back surface to secure slip. However, it has been pointed out that the rough surface provided on these back surfaces is transferred to the overlapping surface when the magnetic tape is wound up, and impairs the magnetic properties.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a heat-resistant synthetic resin film which exhibits favorable mechanical properties and can be reduced in thickness as various base films, without deteriorating the slipperiness in the production process or as a product. It is an object of the present invention to provide a film having a very smooth surface roughness required for various uses.

[0008]

Means for Solving the Problems The present inventors have found that even if the fine surface is smooth, there is a surface structure having no problem in practical use, and have completed the present invention.
That is, an object of the present invention is to provide an inactive fine particle having an average thickness of 2 to 8 μm made of a heat-resistant resin and having an average particle diameter of 5 to 150 nm in an amount of 0.005 to 1.0% by weight and an average agglomeration degree of 1
A film containing at least one surface of which is dispersed and has a center plane average roughness (SRa) of 0.1 to 10 as viewed at the resolution of an optical surface roughness meter.
nm, the maximum protrusion height (Zmax) measured by an atomic force microscope is 5 to 100 nm, and at least one surface of the film has a two-dimensional smooth sine curve approximation (hereinafter, referred to as a sine curve) in the surface direction. "Surface undulation"), and the center line depth of the undulation is 0.1 to 1.5 .mu.m.
m, the wavelength of the undulation is 0.05 to 5 mm, and the dynamic friction coefficient is 0.5 or less.

The heat resistance of the film of the present invention is defined, for example, by the heat shrinkage, and is represented by those having a heat shrinkage at 200 ° C. of 2% or less. The thickness of the film of the present invention is 2 to 8 μm.
When the thickness is less than m, it is difficult to provide the surface undulations of the present invention, and in the case of a thick film, the rigidity of the film itself is increased, and the problem of poor slipperiness, which is an object of the present invention, often does not occur.

The film of the present invention is used for various base films, and preferably has high strength and elastic modulus. For example, in any direction of the film, the strength is not less than 20 kg / mm ^2, more preferably 30 kg / m 2.
It is preferably at least m ² . Although there is no particular limitation on the upper limit of the strength for carrying out the present invention, even an aramid film having excellent mechanical properties is usually about 60 kg / mm ^{2 in} strength that can be realized. Similarly, the elastic modulus is 1000 kg / mm ² or more, more preferably 130 kg / mm ² or more.
It is preferable that it is 0 kg / mm ² or more. The upper limit of the elastic modulus is not particularly limited, but the achievable elastic modulus of the aramid film having excellent mechanical properties is about 2500 kg / mm ² .

The properties of these films should be satisfied in both the longitudinal direction and the width direction, but they do not necessarily have to be the same, and it is possible to enhance either property according to the purpose. This may be performed by any of a so-called balance type in which the characteristics in the longitudinal direction and the width direction are almost equal, and a uniaxial tension type in which the tension is applied in either direction. At least one side of the surface of the film of the present invention is subjected to photoelectric conversion in a field of view of an interference phase contrast microscope with a horizontal resolution of 1 μ or less, data processing is performed, and the surface roughness is measured. 1 to 1
It is 0 nm, preferably 0.5 to 10 nm, and more preferably 0.8 to 6 nm. The object of the present invention cannot be achieved with a surface roughness of SRa exceeding 10 nm.

In the film of the present invention, the substantial roughness of the film surface is important in addition to the roughness observed in units of optical resolution. The substantial roughness of the film surface can be accurately measured by an atomic force microscope (AFM). In order to achieve the object of the present invention, the maximum projection height (Zmax) measured by AFM is 5 to 100 nm, preferably 10 to 7 nm.
0 nm, more preferably 10 to 30 nm when used for a metal thin film type magnetic tape.
If the surface roughness of the fine projections exceeds m, the requirements as the base film of the present invention cannot be achieved.

The film of the present invention contains fine particles as a so-called lubricant in an amount of 0.005 to 1.0% by weight, preferably 0.01 to 0.5% by weight, in order to control the surface roughness and the like. % By weight. When the amount of the fine particles is less than 0.005% by weight, problems such as poor slippage of the film in the film production step or the magnetic tape production step, impairment of stable running, and generation of wrinkles may be avoided, and thus are avoided. Should.

The fine particles may be contained uniformly in the whole film, or may be contained only in the surface layer of the film or in a concentration different in the thickness direction. Fine particles should originally exist independently, but it is known that ultrafine particles are easily aggregated and aggregated. It is necessary that the state of aggregation is 1 to 100, preferably 1 to 20, more preferably 1 to 10 as an average degree of aggregation.
If the average cohesion exceeds 100, the smooth surface aimed at by the present invention cannot be realized.

It is necessary that the fine particles be inert particles which are not denatured by a solvent used in the production of the film, a finishing agent for the film, or a solvent used in coating the film with a magnetic layer. Examples of such fine particles include organic compound and inorganic compound fine particles.
Usually, for example, SiO ₂ , TiO ₂ , ZnO, Al ₂ O
₃ , fine particles of inorganic compounds such as CaSO ₄ , BaSO ₄ , CaCO ₃ , carbon black, zeolite, and other metal powders, and organic compounds such as carbon, carbon fluoride, and fluororesin.

The average particle diameter of the lubricant particles is 5 to 5.
150 nm, preferably 20 nm to 110 nm,
If the particle size is too small, the particles are likely to be aggregated, and even if the particle size is large, the height of the fine projections formed is not only out of the range intended by the present invention, but also coarse projections due to the aggregated fine particles, That is, the number of coarse protrusions having a height of 273 nm or more increases, and when used as a magnetic tape, the head is lifted up, which increases recording and reproduction errors, which is not desirable. The film of the present invention preferably has a number of coarse projections having a height of 273 to 546 nm of 100.
The number of coarse projections having a size of 300 or less and 546 nm or more per cm ² is also 100 or less, more preferably 10 or less, respectively.
0 or less, 20 or less.

The most characteristic feature of the film of the present invention is that at least one surface of the film has a gentle undulation similar to a sine curve in a two-dimensional plane in the surface direction as surface undulation, and the center line depth of the undulation is small. 0.1 to 1.5 μm, and has a gentle undulating structure such that the undulation wavelength is 0.05 to 5 mm. The provision of such a structure on a film is a unique one that has never been proposed before. With this structure, even if the film has a smooth surface as described above, the coefficient of dynamic friction is 0.5%. Hereinafter, a film with good handleability of preferably 0.45 or less, more preferably 0.4 or less can be provided. If the surface undulation is gentler, that is, if the wavelength of the undulation exceeds 5 mm or if the depth of the undulation is less than 0.1 μm, the sliding effect of the present invention cannot be obtained, and the undulation is further. In other words, if the undulation wavelength is less than 0.05 mm or the depth exceeds 1.5 μm, the performance as a base film may be impaired and should be avoided.

S representing the smoothness of the surface of the film of the present invention
The measured value of Ra is defined as a value including the surface undulation, and is displayed larger than SRa of a plane along the undulation due to the influence of the surface undulation. S along the undulations minus surface undulations
Ra can be measured by performing a high-pass filter treatment with a cutoff wavelength of 25 μm, and it is understood that the film of the present invention has a high smoothness of about 0.01 to 6 nm. Similarly, the microscopic roughness distribution is
The center plane root mean square roughness (RMS) measured by AFM is 0.1 to 5 nm. In carrying out the present invention, it is often sufficient that at least one surface of the film satisfies the above range, but it is recommended that both surfaces satisfy the above requirements. In this case, the smoothness and surface undulations on both sides of the film may be the same or different within the scope of the present invention.

The above-mentioned film of the present invention comprises, for example, 0.005 to 150 nm of inert fine particles having an average particle size of 5 to 150 nm.
In forming a liquid crystal dope of a liquid crystal-forming aramid containing 1.0% by weight, prior to adjusting the liquid crystal dope, the fine particles having an average agglomeration degree of 100 in a solvent to be used.
And then 98% by weight of 5μ or more particles
After filtering through a precision filter that can be filtered as described above, the dope is adjusted until the fine particles start to aggregate again, and the ratio of the belt take-up speed to the calculated linear discharge speed of the dope from the die (referred to as draft ratio). It is realized by a method of casting at 1.5 or more, then converting to an isotropic phase, and then solidifying.

The above-mentioned film of the present invention is characterized in that inert fine particles having an average particle size of
In a method of forming a film using a liquid crystal dope of a liquid crystal-forming aramid containing 1.0% by weight, the liquid crystal dope is adjusted to two or more phases having different viscous behaviors, and at least one phase is composed of fine particles dispersed in an island shape. The solution forming the sea component is substantially a sea-island dope composed of a heat-resistant synthetic resin and its solvent. Prior to adjusting the liquid crystal dope, the fine particles are dispersed in the solvent used until the average agglomeration degree is 100 or less. Then, after filtering the particles of 5μ or more with a precision filter capable of filtering 98% by weight or more of the particles, the dope is adjusted until the fine particles start to aggregate again, and the method is cast at a draft rate of 1.5 or more. it can. As the heat-resistant resin that can be used in these methods, a part of an aramid resin or a polyimide resin can be used.

The aramid resin used in the present invention is a resin substantially composed of a unit selected from the group consisting of the following structural units. —NH—Ar ₁ —NH— (1) —CO—Ar ₂ —CO— (2) —NH—Ar ₃ —CO— (3) where Ar ₁ , Ar ₂ and Ar ₃ are at least one aromatic ring And may be the same or different. Representative examples of these include the following.

[0022]

Embedded image

Further, those in which a part of hydrogen on the ring of these aromatic rings is substituted with a halogen group, a nitro group, an alkyl group, an alkoxy group or the like are also included. X is -O-,
_{-CH 2 -, - SO 2 -} , - S -, - CO- is a group such as. In particular, an aramid resin in which 80 mol% or more of all the aromatic rings are bonded at the para position can form a liquid crystal dope at a critical concentration or more, and is preferable in producing the film of the present invention. As the polyimide resin used in the present invention,
The polymer has at least one aromatic ring and at least one imide group in the repeating unit of the polymer, and is represented by the following general formula (2) or (3).

[0024]

Embedded image

[0025]

Embedded image Here, Ar ₄ and Ar _{6 each} include at least one aromatic ring, and two carbonyl groups forming an imide ring are bonded to adjacent carbon atoms on the aromatic ring. This Ar ₄ is
Derived from aromatic tetracarboxylic acid or its anhydride.
The following are typical examples.

[0026]

Embedded image Here, Y is -O -, - CO -, - CH 2 -, - S-,
—SO ₂ — and the like. Ar ₆ is derived from tricarboxylic anhydride or its halide. The following are typical examples.

[0027]

Embedded image Here, Ar ₅ and Ar ₇ contain at least one aromatic ring and are derived from aromatic diamines and aromatic isocyanates. The following are typical examples of Ar ₅ or Ar ₇ .

[0028]

Embedded image

Here, those in which some of the hydrogen atoms on the rings of these aromatic rings are substituted with halogen groups, nitro groups, alkyl groups, alkoxy groups, etc. Z is -O-,-
CH ₂ —, —S—, —SO ₂ —, and —CO—. In particular, a polyimide resin in which 80% or more of Ar ₅ and Ar ₇ are aromatic rings bonded to the para position is preferable for producing a film used in the present invention. Further, in carrying out the present invention, the aramid resin or the polyimide resin used for producing the film includes, in addition to the above-mentioned lubricant, antioxidant, unless the properties of the film are impaired or contradicted the purpose of the present invention. Agents, other additives, and other polymers may be included.

The film also contains coloring agents such as dyes and pigments, flame retardants, antistatic agents, antioxidants, and other modifiers, as long as they do not contradict the object of the present invention. Is also good. The method for producing the film of the present invention is not particularly limited, and a production method suitable for each resin may be employed. First, as for the aramid resin, in the case of those soluble in an organic solvent, it is polymerized directly in a solvent, or once isolated and redissolved to form a solution, and then formed into a film by a dry method or a wet method, Also,
Those hardly soluble in organic solvents such as polyparaphenylene terephthalamide (PPTA) are dissolved in concentrated sulfuric acid or the like to form a solution, and then formed into a film by a dry method or a wet method.

On the other hand, with respect to the polyimide resin, a tetracarboxylic anhydride is reacted with an aromatic diamine in an organic solvent to obtain a polyamic acid. The solution is obtained by dissolving, and they are formed into a film by a dry method or a wet method. In the dry method, the solution is extruded from a die, cast on a support such as a metal drum or an endless belt, and the drying or imidization reaction proceeds until the cast solution forms a self-supporting film.

In the wet method, the solution is extruded directly from a die into a coagulating liquid, or cast on a metal drum or an endless belt in the same manner as in the dry method, and then guided into the coagulating liquid and coagulated. The film having a smooth surface of the present invention is produced by mixing a predetermined amount of the above-mentioned fine particles into an aramid resin or a solution of polyimide or a polyamic acid which is a precursor of polyimide, and forming a film of this solution.

In obtaining the film having the surface roughness of the present invention,
The dispersion of the fine particles is important. Fine particles cannot be achieved in a sufficiently dispersed state by directly adding only fine particles to the resin solution, and should be avoided. The fine particles are pre-dispersed in the solvent used for the polymerization of the resin, or in the case of re-dissolving the resin, are pre-dispersed in the solvent used for dissolution or It is dispersed in the resin solution by a method such as adding to the resin solution and mixing.

As for the dispersion state of the fine particles, it is desirable that each fine particle is completely dispersed alone. However, it is actually difficult to achieve complete dispersion, and the average degree of aggregation of the fine particles is 1 to 1.
100, preferably 1 to 20, more preferably 1 to 1
If 0, the purpose of the present invention can be achieved. As a method of dispersing the fine particles, various homogenizers are used,
In particular, an ultrasonic homogenizer is recommended because of its excellent dispersing power.

As a method for improving the dispersion state of the fine particles,
Monodispersed particles of colloidal particles are commercially available, and it is preferable to dilute and use them in order to achieve a dispersed state with an average cohesion of 10 or less. Care should be taken because the expected effect may be difficult to achieve and the desired effect may not be obtained. In particular, when an amide-based solvent in which an inorganic salt is dissolved as a solubilizing agent or concentrated sulfuric acid is used as a solvent, the colloidal fine particles are easily diluted with the same solvent as the dispersion because the aggregation of the colloidal fine particles easily occurs. After that, it is important to consider that the resin is mixed with a solvent that dissolves the resin under sufficient stirring.

Prior to being used for polymerization or dissolution of the resin, the fine particle dispersion liquid dispersed in the solvent is filtered with a filter capable of filtering undispersed or agglomerated fine particles of 5 μm or more to 98% by weight or more. It is important to do it.
Further, the fine particles once finely dispersed often aggregate with time, and it is preferable to use the fine particles immediately after the dispersion. The type of filter used here is not particularly limited, and various types of metal or carbon particles are sintered, metal fiber woven or non-woven fabric is sintered, and a plastic film provided with micropores is provided. , Etc. are exemplified.

The film having a surface unevenness which is a feature of the present invention is obtained by extruding a liquid crystalline dope of PPTA or other aramid from a die and applying a certain stretching when casting it on an endless belt to give a liquid crystal domain. By embossing the film surface, or by mixing and dispersing another resin dope in the resin dope used in the present invention so as to disperse it into a sea-island shape, and stretching it at the time of casting in the same manner, the island portion resin is stretched. It can be manufactured by a method of forming undulations. When using a liquid crystal dope, the higher the ηinh of the aramid resin, the more easily the surface undulations are increased, and those having a range of usually 5.0 to 7.5, preferably 5.5 to 6.5 are used.

When using the sea-island dope, the dope is adjusted by dissolving in the same solvent as the heat-resistant resin forming the film and adding a required amount of a second resin which is phase-separated from each other. Although it is appropriately selected depending on the type of the conductive resin, aliphatic nylons, polyketones, polyetherketones, polysulfones, and the like are used in addition to the aramid resin and the polyimide resin. In order to generate the undulations preferable in the practice of the present invention, the dope elongation should be generally selected to be 1.5, preferably 2 or more, although it depends on the properties of the dope. The upper limit of the draft ratio varies depending on the viscosity behavior of the dope, but is generally selected to be 7 or less.

Next, these films are washed and removed of solvents and inorganic salts in the films, and are stretched, dried and dried.
After undergoing heat treatment and the like, it is wound up. As for the conditions of washing, drying, and heat treatment, methods and conditions used for each resin film may be used. In any of these steps, various finishing treatments such as dyeing, corona treatment, and humidification treatment may be performed as long as the effects of the present invention are not impaired.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In the examples,% not particularly indicated is% by weight. [Method of measuring characteristics] The method of measuring characteristic values according to the present invention is as follows. (1) Method of measuring film thickness, strength, elongation, and elastic modulus The film thickness is measured with a dial gauge having a measurement surface having a diameter of 2 mm. The strength, elongation, and elastic modulus were measured using a constant-speed elongation-type high-elongation measuring instrument at a measurement length of 100 mm and a pulling speed of 50 mm / min.

(2) Method of Measuring Heat Shrinkage A 2 cm × 5 cm sample piece was cut out from the film, and 4 c
The mark is made by making a mark with a knife at intervals of m.
After leaving for 72 hours in an atmosphere of 5% RH, the distance between the labels was read and measured with a microscope, and then left in a hot air oven at 200 ° C. for 2 hours without restraining, then again at 23 ° C. and 55% RH. After leaving for 72 hours in the atmosphere of
The distance between the labels was read and measured with a microscope.

(3) Measurement method of center plane average roughness (SRa) by optical microscopy The definition of SRa is described in, for example, "Measurement of surface roughness,
Evaluation method ”(Sogo Gijutsu Center, 1983), and a method of calculating and processing an interference image of an interference phase contrast microscope was used. That is, ZYGO's New Vi
Using an ew 100 type surface roughness measuring device, SRa was measured at any three points of the film with an objective lens magnification of 40 times and a camera resolution of 550 nm, and expressed as an average. A high-pass filter was not applied to evaluate the surface smoothness including the effect of surface undulation.

(4) The maximum protrusion height (Zmax) and the center plane root mean square (R) measured by an atomic force microscope (AFM)
MS) Measurement Method A film was fixed on a silicon wafer with a carbon paste, and TMX2010 manufactured by Topometrix was used.
Using a Discoverer-type AFM, a range of 5 μm × 5 μm was observed at a scanning speed of 2 Hz in a non-contact mode. In the image processing, a three-dimensional leveling process was performed. In addition, both Zmax and RMS are 10
Expressed as the average of the measured values of the visual field.

(5) Method of measuring surface undulation depth and undulation wavelength Using a ZYGO New View 100 type surface roughness measuring device, objective lens magnification 2.5 times, camera resolution 8.8 μm, cutoff 5 mm. Optional 3 of film
The depth is represented by the PV value measured for each point, and the wavelength is represented by the dominant wavelength obtained by FFT analysis of the undulation of the center line.

(6) Method of Measuring Average Aggregation Degree of Fine Particles A thin sample having a thickness of about 100 nm was cut out from a film by a conventional method, observed with a JEOL JEM200FX transmission type microscope at a magnification of 50,000, and if necessary, from a plurality of visual fields. 50 of fine particle aggregates (including those that exist alone)
The number of the fine particles constituting each of them or each of them which are aggregated and dispersed is counted and expressed as an average value.

(7) Coarse projections Al is uniformly vacuum-deposited to a thickness of 20 nm on the surface of the film, and halogen monochromatic light having a wavelength of 0.546 μm is used.
Any 3c at 200x magnification using optical multiplex interference microscope
By observing the film surface of m squares, one interference fringe generated with respect to the protrusion of the protrusion was determined to be 0.273 to 0.546 μm.
As a coarse projection having a height of m (hereinafter abbreviated as H1),
Those having two or more interference fringes are counted as coarse projections having a height of 0.546 μm or more (hereinafter abbreviated as H2), and the number of projections in the visual field converted to 100 cm ² is 1
Expressed as the average of zero observations.

(8) Coefficient of dynamic friction The film slit to a width of 8 mm was made of stainless steel having a diameter of 20 mm which had been cleanly wiped off prior to measurement.
The film is run at a speed of 3.3 cm per second while applying a tension (T ₁ ) of 50 g so that the film comes into contact with the fixed guide pole at π radian, and the tension T ₂ required to pull out the film from the fixed guide pole is applied. Is measured. T
_{For 2} , the average value recorded per 1 m of the film after the tension was stabilized was used. The dynamic friction coefficient μk is obtained by the following equation.

Μk = 1 / π · ln (T ₂ / T ₁ )

(9) Method for measuring ηinh Using 98% sulfuric acid as a solvent, polymer concentration 0.5 g / 100
The ml of the diluted solution was measured in a conventional manner at 35 ° C. using an Ostwald viscometer.

[0049]

Example 1 40% colloidal silica particles of 80 nm
The resulting dispersion was mixed with distilled water to prepare a diluent having a silica concentration of 5%, and 100.6% of concentrated sulfuric acid was passed through a branch pipe through which 100% of sulfuric acid was circulated at a speed of 100 m / min. , A silica diluent was fed and mixed at a ratio of 0.06% by volume / minute, and then filtered with a 5 μm cut stainless steel sintered nonwoven fabric filter.

The silica prepared in this manner is used in an amount of 0.0
Using concentrated sulfuric acid containing 35%, P of ηinh of 6.01
PTA was dissolved so that the polymer concentration became 12.5%, and the dope of PPTA was adjusted. The dope irregularly reflected light during stirring, and was observed under an optical microscope, and was found to be in a liquid crystal state, such as exhibiting optical anisotropy that makes the dark field of a crossed Nicol of a polarizing microscope a bright field.

The PPTA dope was filtered through a 5 μm-cut filter made of sintered stainless steel non-woven fabric, and then cast from a die onto an endless belt at a draft rate of 2.1. Next, the dope is heated and absorbed simultaneously with moisture to convert the dope from a liquid crystal phase to an isotropic phase. The dope is coagulated in 30% sulfuric acid at 10 ° C., neutralized and washed with water. After being stretched by a factor of 1, the film was stretched by a factor of 1.1 in the transverse direction with a clip tenter, dried with hot air while maintaining a fixed length, and then heat-treated at 450 ° C. while holding the film with a tenter, followed by winding.

The obtained film had a thickness of 5.2 μm, and the physical properties of the film were as follows:
Strength is 42, 43 kg / mm ² , elongation is 18, 20%,
The elastic modulus is 1500, 1510 kg / mm ² , the heat shrinkage at 200 ° C. is 0.2 and 0.2%, and the surface undulation depth is 0.2.
42 μm, undulation wavelength 0.7 mm, average cohesion of silica 3.5, SRa 4.5 nm, Zmax 70.5 n
m, RMS is 3.3, H1 of the coarse projection is 41,
H2 was 11 pieces. The coefficient of kinetic friction of the film is 0.2
It was 2.

[0053]

Comparative Example 1 For comparison, PPT with ηinh of 4.96
A PPTA film was produced in exactly the same manner as in Example 1 except that A was used and the draft ratio was 1.2. The obtained film has a thickness of 5.5 μm, and the physical properties of the film are 43 and 41, respectively, in the longitudinal direction and the width direction.
kg / mm ² , elongation 21, 21%, elastic modulus 150
5, 1520 kg / mm ² , 200 ° C. heat shrinkage of 0.
2, 0.2%, surface undulation depth 0.06 μm, undulation wavelength 0.7 mm, average cohesion of silica 3.3, S
Ra is 2.0 nm, Zmax is 70 nm, and RMS is 3.
The number of coarse projections was 38 for H1, and 8 for H2. The coefficient of dynamic friction of the film was 0.55.

[0054]

Example 2 A liquid crystal dope of PPTA of Comparative Example 1
5% polymetaphenylene isophthalamide (PMIA) is added to TA to make the liquid crystal phase of PPTA
A film was produced in exactly the same manner except that MIA was used as an isotropic phase. The obtained film had a thickness of 5.3 μm, and the physical properties of the film were 35 and 34 kg / mm ² , the elongation was 18 and 17%, and the elastic modulus was 1350 and 1300 kg in the longitudinal direction and the width direction, respectively. / Mm ² , heat shrinkage at 200 ° C. is 0.5 and 0.5%, and surface undulation depth is 0.5
μm, undulation wavelength 1.0 mm, average agglomeration degree of silica 3.2, SRa 5.5 nm, Zmax 70 nm, R
MS was 3.5, and H1 and H2 of the coarse projections were 50 and 15, respectively. The coefficient of dynamic friction of the film was 0.20.

[0055]

Example 3 A colloidal silica dispersion containing 40% of spherical silica having an average particle size of about 45 nm in water was diluted with distilled water to a silica concentration of 10% while stirring, and then the diluent was continuously added. 100.5 for ultrasonic ultrasonic homogenizer
% Sulfuric acid, and concentrated sulfuric acid having a silica concentration of 0.004% was adjusted. Using the obtained concentrated sulfuric acid, a PPTA film was prototyped in the same manner as in Example 1.

The obtained film has a thickness of 5.1 μm, and the physical properties of the film are as follows:
Strength is 42,44 kg / mm ² , elongation is 19,20%,
The elastic modulus is 1520, 1550 kg / mm ² , the heat shrinkage at 200 ° C. is 0.2 and 0.2%, and the surface undulation depth is 0.2.
44 μm, undulation wavelength 0.7 mm, average cohesion of silica 2.1, SRa 2.4 nm, Zmax 40.2 n
m, RMS is 2.0, and H1 of coarse projections is 23,
H2 was 0. The coefficient of dynamic friction of the film is 0.1.
35.

[0057]

Comparative Example 2 For comparison, PPT with ηinh of 4.75
A PPTA film was produced in the same manner as in Example 3 except that A was used and the draft rate was 1.2. The obtained film had a thickness of 5.2 μm, and the physical properties of the film were 43 and 43, respectively, in the longitudinal direction and the width direction.
kg / mm ² , elongation ²⁰ , 19%, elastic modulus 151
5, 1500 kg / mm ² , 200 ° C. heat shrinkage of 0.
2, 0.2%, average cohesion of silica is 2.3, surface undulation depth is 0.07 μm, undulation wavelength is 0.7 mm, S
Ra was 1.0 nm, Zmax was 40.4 nm, and RMS was 1.9. The number of coarse projections H1 was 19 and the number of H2 was 0. The dynamic friction coefficient of the film could not be measured because the film did not slide smoothly and did not run stably.

[0058]

The film of the present invention is a heat-resistant thin film having extremely smooth surface properties and excellent handleability, and is used as a base film for a magnetic tape, a sublimation type ink ribbon, a heat-resistant protective material and the like. Useful as a film. When the film of the present invention is used as a base film of a magnetic tape, for example, the followability of the magnetic head to the magnetic material surface is not impaired, while the film or the magnetic material surface is made of a surface such as a cylinder, a roll, a pin, and a guide. Has low adhesion to the surface due to the effect of surface undulation, and does not impair the slipperiness. Similar effects can be obtained in other applications.

According to the magnetic tape using the film of the present invention, it is possible to perform magnetic recording with a high recording capacity using a short wavelength signal, which is increasingly demanded in the future, and it is possible to use it for information recording such as multimedia and high quality such as digital high vision. It is possible to provide a magnetic tape useful for recording television images, backing up computer information records in an advanced information society, and the like. In addition, it is possible to provide a high-resolution tape suitable for a proofer application requiring high image quality even in a sublimation type ink ribbon.

Claims (4)

[Claims] An average thickness of a heat-resistant resin is 2 to 8 μm.
m, 0.005 to 1.0% by weight of inert fine particles having an average particle size of 5 to 150 nm, and an average cohesion of 1 to 100.
Wherein at least one surface of the film has a center plane average roughness (SRa) of 0.1 to 10 nm as viewed at the resolution of an optical surface roughness meter,
Maximum protrusion height (Zma) measured by atomic force microscope
x) is 5 to 100 nm, and at least one surface of the film has a gentle undulation approximated by a two-dimensional sine curve in the surface direction, and the center line depth of the undulation is 0.1.
A heat-resistant synthetic resin film having a wavelength of 0.05 to 5 mm and a coefficient of kinetic friction of 0.5 or less. 2. A film having a strength of 20 to 60 kg / mm ² and an elastic modulus of 1000 to 25 in any direction of the film.
2. The heat-resistant synthetic resin film according to claim 1, which has a heat shrinkage of 2% or less at 00 kg / mm ² and 200 ° C. 3. A method for forming a film using a liquid crystal dope of a liquid crystal-forming aramid containing 0.005 to 1.0% by weight of inactive fine particles having an average particle diameter of 5 to 150 nm, wherein the liquid crystal dope is adjusted. Prior to this, the fine particles are dispersed in the solvent used until the average degree of aggregation is 100 or less, and then the particles having a particle size of 5 μ or more are separated by a precision filter capable of filtering 98% by weight or more. At least one surface of the film is characterized by being prepared by adjusting the dope before casting, casting at a draft ratio of 1.5 or more, and then converting to an isotropic phase and then solidifying. It has a gentle undulation approximating a sine curve in a dimension, the center line depth of the undulation is 0.1 to 1.5 μm, the wavelength of the undulation is 0.05 to 5 mm, and an optical surface roughness meter. With a resolution of Center plane average roughness (SRa) is 0.1 to 10 nm, the maximum protrusion height was measured with an atomic force microscope (Zmax) is 5 to 100 nm,
A method for producing a heat-resistant synthetic resin film having a dynamic friction coefficient of 0.5 or less. 4. A method for forming a film using a liquid crystal dope of a liquid crystal-forming aramid containing 0.005 to 1.0% by weight of inert fine particles having an average particle size of 5 to 150 nm, wherein said liquid crystal dope is viscous. Adjusted from two or more phases with different behaviors,
At least one phase is fine particles dispersed in the form of islands, and a sea-island dope in which the solution forming the sea component is substantially composed of a heat-resistant synthetic resin and a solvent thereof. The above fine particles have an average cohesion of 1
And then filtered with a precision filter capable of filtering 98% by weight or more of particles of 5μ or more, then adjusting the dope until the fine particles start to aggregate again, and casting at a draft rate of 1.5 or more. Characterized in that at least one side of the surface of the film has a gentle undulation of a sine curve approximation two-dimensionally in the plane direction, the centerline depth of the undulation is 0.1 to 1.5 μm, The undulation wavelength is 0.05 to 5 mm, and the center plane average roughness (SRa) viewed at the resolution of the optical surface roughness meter is 0.1 to 10 nm.
Wherein the maximum protrusion height (Zmax) measured by an atomic force microscope is 5 to 100 nm and the dynamic friction coefficient is 0.5 or less.