JPH09194607A - Highly elastic and heat resistant long size film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a film satisfying necessary requirements for stable coating without developing wrinkles. SOLUTION: This film has a heat shrinkage of not more than 0.5%, an elastic modulus is the longitudinal direction of not less than 700kg/mm<2> , an elastic modulus is the widthwise direction of not less than 900kg/mm<2> , and an average thickness of not more than 6μm, moreover, the ratio of elastic modulus in the longitudinal direction to that in the widthwise direction is 1.1-1.8, the P-V value of thickness variation of the cycle not more than 50mm in the longitudinal direction of the film is not more than 7% of the average thickness, the P-V value of thickness variations of the cycle not more than 40mm in the widthwise direction of the film is not more than 7% of the average thickness, and the thickness variation in the directions of length and width in total is not more than 10% of the average film thickness.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a very thin, rigid film. More specifically, the present invention relates to a rigid film that can be stably coated without causing wrinkles.

[0002]

2. Description of the Related Art In recent years, as a base film for magnetic tapes for high density recording, ink ribbons for sublimation type thermal transfer printers, etc., heat resistance, high strength and high elastic modulus, for example, 6 μm
The demand for ultra-thin films such as:
However, in the case of coating a very thin film, which has a high elastic modulus of the film and high heat resistance, unlike the conventional thermoplastic polymer, the crystallinity of the polymer is high, It is said that the film is difficult to deform at the coating temperature of, and even if there is a slight change in tension during traveling from roll to roll in the coating process, the film is folded in the length direction of the film and wrinkles are likely to occur. There was a problem. Especially when the adhesiveness of the coating layer is high, wrinkles generated when the film coated with the adhesive is wound off develops in the width direction, and finally wrinkles occur over the entire width.

In addition, when a film is coated while being stretched by applying tension in order to improve a film flatness defect such as so-called one-sided slack, which causes slack in a part of the film, a slight slack is corrected. However, since the film has a high elastic modulus, the applied tension is high, which is also one of the reasons for easily causing wrinkles. By the way, JP-A-6
3-254136 proposes an aromatic polyamide (hereinafter referred to as aramid) film having a thickness of 8 μm or less and a thickness variation of 10% or less, but the stability of the coating process which is the object of the present invention. There is no teaching of sex or disclosure of the periodicity of thickness variation. In addition, JP-A-56-1
In Japanese Patent No. 1624, it is proposed that a magnetic layer is coated on an aramid film film whose elastic modulus in the width direction is 1.3 times or more of that in the length direction to form a magnetic tape. In particular, there is no example of coating on a film having a thickness of 6 μm or less, and there is no teaching of processing stability when coating a magnetic layer.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to achieve an extremely thin high strength of 6 μm or less,
It is an object of the present invention to provide a film having a necessary requirement for stably coating a high elastic modulus film without causing wrinkles.

[0005]

Means for Solving the Problems In the coating process using a conventional high-elasticity / heat-resistant film, particularly an aromatic polyamide film or an aromatic polyimide film, the present inventors surprisingly found that the film had a long length. It was found that there was a short period thickness variation in the direction, and that it was related to the stability of the coating process, and as a result of further study, the elastic moduli in the length and width directions were In relation, even if the film whose variation rate of the thickness of the film in the length direction and the width direction is a specific value or less is applied while applying high tension, wrinkles occur in the length direction even in long-term operation. The present invention has been completed by concluding that stable coating can be carried out without any problems.

That is, in the present invention, the heat shrinkage at 250 ° C. is 0.5% or less, the elastic modulus in the length direction (hereinafter referred to as MD) is 700 kg / mm ² or more, and the average thickness is 6 μm or less. A film having an elastic modulus in the width direction (hereinafter referred to as TD) of 900 kg / mm ² or more, and a ratio of the elastic modulus in the width direction to the length direction of 1.1 to 1.8, and The thickness variation of the film has a P-V value of 7% or less of the average thickness of the thickness variation of 50 mm or less in the length direction and a P-V of the thickness variation of 40 mm or less in the width direction.
The V value is 7% or less of the average thickness, and the variation in the thickness in the length direction and the width direction is 10% of the average thickness of the film.
It is a high-elasticity / heat-resistant long film characterized by the following. With such a structure, it is possible to achieve stable film production without wrinkling in the length direction, which is the object of the present invention.

Further, before the film is wound up, the film is allowed to absorb moisture up to 50% or more of its equilibrium moisture content at 20 ° C. and 60% RH (hereinafter simply referred to as equilibrium moisture content), and then it is rolled. By removing the wrinkles, the problem of wrinkles occurring after the film is removed and the problem of wrinkles occurring when the film is coated. The long film of the present invention is an extremely thin film having an average thickness of about 6 μm or less, and such a film having a high elastic modulus of 9 μm or more, which is a normal film, has sufficient rigidity. Wrinkles, which is a problem of, is unlikely to occur. Here, the average thickness means an average value of thicknesses in the entire length direction and width direction of the film. Further, the length of the long film is not particularly limited, and there are generally 10 m or more, 50 m or more, 100 or more.

The film of the present invention has an MD elastic modulus of 70.
0 kg / mm ² or more, more preferably 900 kg / m
It has an extremely high elastic modulus of m ² or more. The upper limit is not particularly limited, but is generally 2500 kg / mm ² or less. Further, the film of the present invention is intended to have excellent heat resistance. Here, the degree of heat resistance is 250 ° C.
Heat shrinkage at 0.5% or less, more preferably 0.2%
Refers to:

In order to achieve the object of the present invention, the elastic modulus of TD of the film must be sufficiently high, and 900 kg / mm
² or more, more preferably 1100 kg / mm ² or more, further preferably 1300 kg / mm ² or more, and M
It is necessary that the ratio of D to the elastic modulus is 1.1 to 1.8, more preferably 1.15 to 1.5. If these requirements are not met, wrinkles are likely to occur in the coating process. The upper limit of the TD elastic modulus of the film is not particularly limited, but is generally 3000 kg / mm ² .

In order to achieve the object of the present invention, the fluctuation of the film thickness in a short cycle should be avoided because it significantly impairs the stability of the coating process. That is, the length of the cycle that influences is slightly different between MD and TD, and is 5 in MD.
It is necessary that the thickness variation in a cycle of 0 mm or less is 7% or less, more preferably 5% or less, and in TD, the thickness variation in a cycle of 40 mm or less is 7% or less, more preferably 5% or less, These are substantially the same whether they exist independently or simultaneously. Further, from the viewpoint of facilitating industrial production, both MD and TD are preferably 0.02% or more. The thickness variation cycle in the present invention is 1 m or more in the length direction and 1 m or more in the case of 1 m or more in the width direction, and continuously measured over the entire width of the film in the case of less than 1 m, and the variation peak to peak. , Is calculated as the average value of the distance from valley to valley.

The film thickness of the film of the present invention should be 10% or less, more preferably 7% or less over the entire length and width of the film even with respect to the thickness variation over these cycles, which impairs the properties of coated products. There are problems such as the roll being rolled up and the rolled roll being poorly rolled. Further, it is preferably 0.05% or more from the viewpoint of industrial productivity. Here, the thickness variation over the entire length and width of the film is
It is represented by the difference between the maximum thickness and the minimum thickness, which is obtained by measuring the thickness of the entire surface of the film in a scanning manner by the method described below.

In general, the film is wound up without absorbing moisture up to the equilibrium moisture content in the manufacturing process, and most of it is wound up in a dry state. For that reason, only the outer layer absorbs moisture during storage and does not reach the inside, and when the film is rolled out and subjected to processing, only both ends of the film absorb moisture and expand and loosen. Occurs, and a film jump occurs on the coating roll or die, resulting in coating spots. In another embodiment of the invention, the film contains 50% or more, and more preferably 70% or more of the equilibrium moisture content over the entire length and width of the stripped film roll. No problem occurs. Furthermore, not only the coating unevenness is eliminated, but also the running between the rolls has a stabilizing effect, which is effective in achieving the object of the present invention. Also,
The upper limit of the equilibrium moisture content is not particularly limited, but it is preferably 100% or less of the equilibrium moisture content from the viewpoint of preventing film blocking due to excess moisture.

As the polymer constituting the film of the present invention, as a film satisfying these characteristics, a part of the film made of an aramid resin or a polyimide resin can be used. The aramid resin used in the present invention is substantially composed of units 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) Here, at least one Ar ₁ , Ar ₂ and Ar ₃ is present. And may be the same as or different from each other, and typical examples thereof include the following chemical formula 1.

[0015]

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In addition, those in which a part of hydrogen atoms on the aromatic ring are substituted with a halogen group, a nitro group, an alkyl group, an alkoxy group or the like are also included. Also, X is -O-,
_{-CH 2 -, - SO 2 -} , - S -, - CO- , and the like.
In particular, an aramid resin in which 80 mol% or more of all aromatic rings are bonded in the para position is preferable for producing the film used in the present invention.

The polyimide resin used in the present invention is one containing 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.

[0018]

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[0019]

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Where Ar_FourAnd Ar₆Is at least 1
Two carbonyls containing the aromatic ring of, forming an imide ring
The group is attached to adjacent carbon atoms on the aromatic ring. this
Ar _FourIs an aromatic tetracarboxylic acid or its anhydride
Comes from. The following are typical examples. here
Y is -O-, -CO-, -CH_Two-, -S-, -SO_Two
-And so on.

[0021]

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Ar ₆ is derived from tricarboxylic acid anhydride or its halide. 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 .

[0023]

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Here, it also includes those in which a part of hydrogen on these aromatic rings is substituted with a halogen group, a nitro group, an alkyl group, an alkoxy group or the like. Z is —O—, —CH ₂
-, - S -, - SO 2 -, - CO- , and the like. Especially,
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 the film used in the present invention.

Further, the aramid resin or polyimide resin of the present invention contains a lubricant, an antioxidant, other additives, and other polymers as long as the physical properties of the film are not impaired and the object of the present invention is not impaired. It may be. The manufacturing method of the film of the present invention is not basically limited, and a manufacturing method suitable for each resin may be adopted.

As for the aramid resin, if it is soluble in an organic solvent, it is polymerized directly in a solvent, or once the polymer is isolated and then redissolved to prepare a solution, which is then prepared by a dry method or a wet method. Be filmed. Further, those which are hardly soluble in organic solvents such as polyparaphenylene terephthalamide (hereinafter referred to as PPTA) are dissolved in concentrated sulfuric acid or the like to form a solution, and then formed into a film by a dry-wet method or a wet method.

In practicing the present invention, aramid resin tends to undergo a large dimensional change due to moisture absorption due to the affinity of amide bond with water, so that it is necessary to pay particular attention to control the humidity expansion coefficient of the aramid resin film. is there. As a method for controlling the humidity expansion coefficient of the aramid resin film, a method of introducing a Cl group, a NO ₂ group or the like into the main chain of the polymer, a method of sufficiently heat treating the film to promote crystallization, and a film are constituted. Any method such as a method of selecting the type and amount of the binding metal ion to the COOH group at the terminal group of the aramid molecule can be used.

On the other hand, with respect to the polyimide resin, tetracarboxylic acid anhydride and aromatic diamine are reacted in an organic solvent to obtain a polyamic acid, and this solution is used as it is or after once subjected to a ring-closing treatment to form a polyimide, the solvent is again used. To obtain a solution, which is formed into a film by a dry method or a wet method. For both aramid resin and polyimide resin, the film formation is a dry method in which the solution is extruded from a die and cast on a support such as a metal drum or an endless belt.
The cast solution is dried and coagulated until it forms a self-supporting film. In the wet method, the solution is directly extruded 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.

Next, these dry or wet film-formed films are washed with residual solvent or inorganic salt, if necessary, and then subjected to treatments such as stretching, drying and heat treatment. As described above, in any of the film forming methods, the area stretching ratio (represented by the product of the MD stretching ratio and the TD stretching ratio) is 0.9 to
It should be 5.0 times, and preferably 1.0 to 4.
It is 0 times. If the area draw ratio is less than 0.9, the Young's modulus becomes insufficient, which is not preferable. On the other hand, if it exceeds 5.0 times, the film is likely to be broken in the film manufacturing process, which is not preferable.

The method for obtaining the elastic moduli of MD and TD, which is a feature of the present invention, can be achieved by adjusting the draw ratio in each direction within the above area draw ratio. MD orientation is often advanced by the stretching step due to molecular orientation to MD during casting, extension to MD due to process tension in other steps such as washing with water, and the stretching ratios of MD and TD are It needs to be selected in consideration.

The biaxial stretching in MD and TD may be a sequential biaxial stretching method in which they are carried out in separate steps or a simultaneous biaxial stretching method in which they are carried out simultaneously. Usually, heat treatment is performed after the stretching, but the elastic modulus of MD and TD required in the present invention may change. Therefore, when selecting the stretching conditions, it is necessary to consider the characteristic change during the heat treatment. is there.

The heat treatment method is not particularly limited, but since it does not usually impair the flatness of the film, heat treatment is performed while gripping the film with a clip tenter or the like, and residual strain is removed if necessary. Therefore, heat treatment is often performed in a relaxed state. The temperature and time of the heat treatment vary depending on the type of resin used for film production, and may be selected according to each resin and the desired property.

The variation of the film thickness is important in achieving the object of the present invention. That is, when manufacturing an aramid film having a size of 6 μm or less, it is difficult to adjust the lip gap of the die, the landing point varies when the dope is cast on the supporting belt, and the peeling tension from the belt when the film is pulled off varies. In a special case, there is a TD or MD thickness variation of the film thickness such as a small period random variation due to the liquid crystal-doped domain structure, and the variation state of these film thickness also causes wrinkles. It is an important requirement for occurrence.

That is, with respect to the lip gap of the die which causes the thickness variation in a small period of TD, in addition to the die structure capable of finely adjusting the gap, the viscosity of the dope is adjusted by adjusting the lip gap and the local temperature of the die. A method such as using a method of locally changing may be preferably used. Further, in order to stabilize the landing point of the dope on the belt, which causes variation in MD thickness, it is preferable to set the distance between the die and the belt as short as possible, and set to 20 mm or less, preferably 10 mm or less. This significantly reduces the occurrence of thickness variation.

Further, since the film is thin, contains a large amount of a solvent or a coagulant as a swelling agent, and is liable to be deformed due to before heat treatment, the film is dried from the belt. Alternatively, fluctuations in peeling tension when peeling the solidified film should be avoided in terms of thickness fluctuations. Particularly when solidifying by a dry method, since the solvent is heated and evaporated on the belt, the solvent content on the belt surface of the film is large, and the film tends to be difficult to peel off from the belt. Since the temperature is high, the film has a low modulus of elasticity, which tends to cause elongation of the film due to the peeling tension, and a slight change in the peeling tension leads to a change in the thickness. As a method to reduce the thickness variation when peeling the film from the belt,
It is effective to fix the peeling point at a fixed position.For example, there is a method of fixing the peeling point by installing a pressing roll at the peeling point and driving the belt at the same speed as the belt. It is also possible to expect an effect that the pulling tension is not directly applied to the peeling point by pressing along with the roll surface and moving. Also effective is a method of fixing the peeling point by pouring water at the peeling point, in addition to the effect of promoting the coagulation of the film to facilitate peeling, and also helping the peeling by a water stream,
In the dry method, the effect of making the film difficult to stretch can be expected by cooling the film by water injection.

When the liquid crystal dope of aramid is used,
The thickness variation due to the domain structure is the ratio of the casting speed to the belt take-up speed (referred to as draft ratio).
It was found that it becomes remarkable when the value is increased, and it can be reduced by setting the draft ratio to 2 or less, preferably 1.5 or less. In producing a film, it is usually wound into a roll immediately after being subjected to necessary treatment such as heat treatment, and is moisture-proof packaged to prevent moisture absorption during storage until being used, As one embodiment of the present invention, the film is allowed to run in a high temperature and high humidity atmosphere prior to winding to absorb moisture up to 50% or more of the equilibrium moisture content of the film at 20 ° C. and 60% RH. After it has been allowed to roll, it may be scraped off.

In producing the film of the present invention,
Improve the slipperiness of film comrades, blocking phenomenon
To prevent this, fine particles (lubricant) are mixed in the film surface.
It is also possible to form a fine rough surface. With fine particles
There are organic compounds and inorganic compounds, but usually,
For example SiO_Two, TiO_Two, ZnO, Al_TwoO_Three, CaS
O _Four, BaSO_Four, CaCO_Three, Carbon black, Zeo
Inorganic compounds such as lights and other metal powders are used
You. The particle size is 0.005 to 2 μm, and the addition amount is 0.01 to
Often chosen to be 2% by weight. That is, aramid resin or
Or polyimide, or poly (precursor of polyimide)
Mix the above fine particles in the solution of amic acid, and add this solution.
It is manufactured by forming a film. At this time, dispersion of fine particles
To improve the homogeneity of ultrasonic method and stirring method.
Is preferably used.

However, in magnetic tapes, sublimation type printer inks, etc., it is not preferable to form an excessively rough surface by placing importance on slippage, etc., since the characteristics and resolution of the processed products are impaired. In the above application, it is desirable that the surface roughness represented by the center line average roughness (Ra) is selected to be 10 nm or less. In the film of the present invention, a colorant such as a dye or a pigment, a flame retardant, an antistatic agent, an antioxidant, and other modifiers may also be included as long as they do not violate the object of the present invention. Good.

The film of the present invention, having the above-mentioned constitution, can be stably coated without the occurrence of wrinkles. In particular, it is a useful film in the fields of applications such as base films for magnetic recording media, high resolution sublimation printer inks, prepreg films, and thin adhesive tapes. (Method of measuring characteristics) The method of measuring characteristic values according to the present invention is as follows. (1) Method of measuring strength, elongation and elastic modulus The strength, elongation and elastic modulus of the sample were preliminarily 23 ° C. and 55% RH.
After being left in the atmosphere for 48 hours or more, the measurement was carried out in the same atmosphere using a constant-speed elongation type elongation measuring instrument at a measuring length of 100 mm and a pulling speed of 50 mm / min. (2) Method of measuring heat shrinkage A sample piece of 2 cm × 5 cm is cut out from a film and 4c
The mark is made by making a mark with a knife at intervals of m.
After being left in an atmosphere of 5% RH for 48 hours, 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 48 hours under the atmosphere of
The distance between the labels was read and measured with a microscope. (3) Thickness and Method of Measuring Thickness Variation The local variation in thickness of the film was measured by an Anritsu Corporation KG601A type thickness measuring instrument.

The thickness variation of the entire length and width of the film is
Yokogawa Electric Corporation NEW WEBGAGE TYPE
It was measured with an 8670 β-ray thickness gauge. The average thickness of the film is represented by an average value of the entire length and the entire width of the β-ray thickness meter. (4) Method of measuring moisture content of film A sample piece of a film is sampled, its weight is measured, and the material is absolutely dried, and the weight is measured again. The weight loss during that time is regarded as water content and expressed as a percentage relative to the absolutely dry weight.

The equilibrium moisture content of the film is 20 for the film.
It is defined as the water content after being left in an environment of 60 ° C and 60% RH for 48 hours. (5) Center Line Average Roughness (Ra) The definition of Ra is given, for example, in “Measurement and Evaluation Method of Surface Roughness” by Jiro Nara (General Technology Center, 1983). Surface roughness measuring machine (ET-3
0) using a stylus tip radius of 0.5 μm, stylus load of 5 m
The measurement was performed 10 times under conditions of g and cutoff value of 80 μm, and the average value is shown.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, examples and comparative examples will be shown in order to deepen the understanding of the present invention, but it goes without saying that the present invention is not limited thereto. In addition, in each example,% unless otherwise specified indicates% by weight. (Production of Films Used in Examples and Comparative Examples) Polyparaphenylene terephthalamide (hereinafter referred to as PPTA) was preliminarily treated with an ultrasonic homogenizer so that 0.04 μm silica particles were 0.3% based on PPTA. The polymer was dissolved in dispersed 99.9% concentrated sulfuric acid so that the polymer concentration was 12%, 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.

After filtering this PPTA dope with a 10 μm cut filter on a sintered non-woven fabric of stainless steel,
Cast on an endless belt made of tantalum moving from the die at a speed of 10 m / min. At this time, the draft ratio was set as shown in Table 1 by changing the lip gap of the die. The distance between the die and the belt was set as shown in Table 1. Then, heat treatment and moisture absorption treatment were simultaneously performed on the belt to convert the dope from a liquid crystal phase to an isotropic phase.
The sample, which was fixed in the 40% sulfuric acid at 0 ° C and fixed at the peeling point with the pressing roll shown in Table 1 from the belt, was fixed at the peeling point with a rubber roll having a diameter of 30 cm, and spread about 90 degrees to the roll. After running along with each other, it is sent to the next step, neutralized, washed with water, stretched in the machine direction under the conditions shown in Table 1, then stretched in the transverse direction with a clip tenter, and then dried with hot air while maintaining a constant length state. Then, after heat-treating at 400 ° C. in a constant length state, both ends of the film are slit and removed.
An aramid film (samples a to e in Table 1) was manufactured by rolling a roll of a length of 5000 m with a width of 08 mm.

After the heat treatment step, the film was continuously moistened by exposing it to high-humidity air of 90 ° C. heated to 110 ° C. for 10 seconds, and then slitting and winding were carried out to find a place on the film. In the same manner as above, an aramid film (samples f to g in Table 1) having a water content of 2.2% (68% of the equilibrium water content) was produced. The obtained PP
The average thickness of the TA film was 4.5 μm, and the variation in thickness over the entire length and width was 7.8% of the average thickness.
The thickness variation and physical properties of the film in a short cycle were as shown in Table 2. The thickness variation of the film in a short cycle was obtained from the thickness measured in the length direction of 1.5 m and in the width direction of the entire width. In addition, Ra of all films is 3.2 n
It was between m and 3.5 nm.

[0045]

Example 1 Using 100 m of sample a in Table 1, in order to adjust the flatness of the film, a methyl ethyl ketone solution containing 50% of epoxy resin and other solids was applied with a microgravure coater while applying a tension of about 2 kg. Applied,
Then, after drying with hot air at 135 ° C, a polypropylene film of 30 μm is laid on the coated surface and then rolled up, and a prepreg film coated with a B-stage epoxy resin layer with a thickness of 5 μm is applied to each roll of coating equipment. No vertical wrinkles were generated between the films, and no wrinkles or dulling occurred even when superposed on a polypropylene film, and stable production was possible.

[0046]

COMPARATIVE EXAMPLE 1 Samples b, c, d and e shown in Table 1 were coated in the same manner as in Example 1. In each sample, vertical wrinkles were generated to some extent, and a prepreg could not be manufactured stably.

[0047]

Example 2 Using 100 m of sample f in Table 1, a methyl ethyl ketone solution containing 40% of a pressure-sensitive adhesive containing silicon rubber as a main component was applied under the same equipment and conditions as in Example 1, and the temperature of 120 ° C. After drying with hot air, it was scraped off. A thin film pressure-sensitive adhesive tape in which a silicon-based pressure-sensitive adhesive layer was laminated in a thickness of 20 μm could be manufactured without problems such as wrinkles.

[0048]

Example 3 Using 2000 m of sample a in Table 1,
Under the same equipment and conditions as in Example 1, butyl acetate-isobutyl ketone containing 31.2% γ-Fe ₂ O ₃ , 2.2% polyester polyurethane and 3.8% vinyl chloride vinyl acetate copolymer. The (3: 2) mixture solution was applied, dried with hot air at 100 ° C., and then scraped off. A thin film magnetic tape having a magnetic layer laminated in a thickness of 3 μm could be manufactured without problems such as wrinkles.

[0049]

Comparative Example 2 Example 2 was repeated except that the sample g in Table 1 was used. Unlike Example 2, vertical wrinkles were generated in the process of rolling up the pressure-sensitive adhesive film, which developed on the film rolls that were rolled up one after another, and finally wrinkled over almost the entire width.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

According to the present invention, a heat-resistant film having a high elastic modulus of 6 μm or less can be stably coated without causing wrinkles. Therefore, in a sublimation type printer ink, heat resistance, high thermal conductivity and high resolution can be obtained. It can be realized, and the thickness of the magnetic tape can be made extremely thin, and a high capacity cassette can be realized. An extremely thin heat-resistant release film can be realized by coating with silicone resin or fluorine resin, and a thin composite material can also be realized by coating with curable resin such as epoxy resin. Furthermore, it has become possible to manufacture adhesive tape, which has been difficult until now, and realize thin heat-resistant insulating materials.

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Claims (4)

[Claims] 1. A film having a thermal shrinkage at 250 ° C. of 0.5% or less, an elastic modulus in the length direction of 700 kg / mm ² or more and an average thickness of 6 μm or less, and an elastic modulus in the width direction. Is 900 kg / mm ² or more, the ratio of the elastic moduli in the width direction to the length direction is 1.1 to 1.8, and the fluctuation of the film thickness is 50 mm or less in the length direction. The P-V value of the thickness variation is 7% or less of the average thickness, the P-V value of the thickness variation of the width direction of 40 mm or less is 7% or less of the average thickness, and the length direction and the width direction. A long film having high elasticity and heat resistance, characterized in that the variation in the total thickness is 10% or less of the average thickness of the film. 2. A film having a thermal shrinkage at 250 ° C. of 0.5% or less, an elastic modulus in the longitudinal direction of 700 kg / mm ² or more and an average thickness of 6 μm or less, and an elastic modulus in the width direction. Is 900 kg / mm ² or more, the ratio of the elastic moduli in the width direction to the length direction is 1.1 to 1.8, and the fluctuation of the film thickness is 50 mm or less in the length direction. The P-V value of the thickness variation is 7% or less of the average thickness, the P-V value of the thickness variation of the width direction of 40 mm or less is 7% or less of the average thickness, and the length direction and the width direction. A high-elasticity, heat-resistant long film for coating, characterized in that the variation in the total thickness is 10% or less of the average film thickness. 3. The highly elastic and heat resistant long film according to claim 1, wherein the polymer constituting the film is an aromatic polyamide or a polyimide. 4. The high elasticity and heat resistant length according to any one of claims 1 to 3, wherein the entire length and width of the film contain 50% or more of the equilibrium moisture content of the film at 20 ° C. and 60% RH. Shaku film.