JP2664959B2 - Metallized film - Google Patents

Description

The present invention relates to poly (p-phenylene terephthalamide)
(Hereinafter referred to as PPTA). The present invention relates to a metallized film substantially provided with a thin metal film on a heat-resistant film excellent in dimensional stability and substantially composed of PPTA.

[Conventional technology]

Para-oriented aromatic polyamides have particularly excellent crystallinity and high melting point, and also have high heat resistance and high mechanical strength due to their rigid molecular structure. It is a molecular material.

A method for producing a film from a para-oriented aromatic polyamide containing PPTA is disclosed in, for example, Japanese Patent Publication No. Sho 57-17886, in which an optically anisotropic dope is exchanged into an optically isotropic dope and solidified. Things. However, it has been found that the film produced by this method is still insufficient in dimensional stability as it is. For example, since the expansion due to moisture absorption is quite large and the heat shrinkage is also large, a so-called metallized film in which a metal thin film is provided on the film surface by vapor deposition, sputtering, or the like is used. It has been found that deformation such as warpage and waving occurs. These can be said to be issues common to all conventionally known PPTA films.

On the other hand, an attempt to improve the moisture absorption properties of a para-oriented aromatic polyamide film is disclosed in, for example, Japanese Patent Publication No. Sho 56-46421. This publication describes an aromatic polyamide film in which an aromatic group is substituted with chlorine, and the dimensional stability of moisture absorption seems to be increased by the effect of the introduced chlorine atom. However, since the thermal dimensional stability is rather reduced, the above-mentioned problem occurs at a high temperature when metallized. At a high temperature, there is a disadvantage that the metal thin film is corroded due to the corrosiveness of the introduced chlorine atoms.

[Problems to be solved by the invention]

An object of the present invention is to provide a PP having excellent mechanical performance and heat resistance.
An object of the present invention is to provide a metallized film having excellent dimensional stability to both heat and humidity by using a TA-based polymer.

[Means for solving the problem]

The present inventors have conducted intensive studies to obtain a PPTA-based film meeting the above-mentioned object, and have obtained the following findings. That is, a method of first preparing an optically anisotropic dope of a para-oriented aromatic polyamide, which is disclosed in Japanese Patent Publication No. 57-17886, and then optically anisotropically coagulating the same to solidify it, has a transparent mechanical performance. In the method of obtaining an excellent film,
By performing the drying at a high temperature and without shrinkage, the crystallinity and molecular chain orientation of the film are increased, and thereafter, by heat-setting at a temperature slightly lower than the drying temperature, heat,
A film with extremely excellent dimensional stability against humidity and external force can be obtained, and this film has a very small coefficient of thermal expansion, so its dimensional change is small. The inventors have found that deformation is unlikely to occur, and have further studied based on these findings, and as a result, have reached the present invention.

The present invention is a film comprising a substantially para-oriented aromatic polyamide having a logarithmic viscosity of 3.5 or more, from 25 ° C to 25 ° C.
The coefficient of thermal expansion up to 0 ℃ is (0-15) × 10 ^-6 mm / mm / ℃, 250
The film has a heat shrinkage at 0.1 ° C of 0.1% or less, a moisture expansion coefficient at 25 ° C of 30 × 10 ⁻⁶ mm / mm /% RH or less, and a moisture absorption at 25 ° C and 50% RH of 2.5% by weight or less. A metallized film having a metal thin film provided on at least one surface.

The PPTA used in the present invention is substantially Which is conveniently produced from a conventionally known paraphenylenediamine and terephthaloyl chloride by a low-temperature solution polymerization method. In the present invention, a small amount of other components may be copolymerized or blended as long as the effects of the present invention are not impaired. Examples of such methanephenylene, 4,4'-
Diphenylene, 4,4'-diphenylene ether, 3,4'-
Aromatic polyamide having a skeleton of diphenylene ether or the like, PPTA having an aromatic ring substituted with an alkyl or nitro group, or the like can be given.

If the polymerization degree of the polymer of the present invention is too low, a film having good mechanical properties cannot be obtained, so that the logarithmic viscosity ηinh of 3.5 or more, preferably 4.5 or more (measured at 30 ° C. by dissolving 0.5 g of the polymer in 100 ml of sulfuric acid, at 30 ° C.) The degree of polymerization which gives the given value) is selected.

The film used for the metallized film of the present invention should satisfy the following requirements.

First, the coefficient of thermal expansion of the film used in the present invention was measured in the range of 25 to 250 ° C. (0 to 15) × 10 ⁻⁶ mm / mm
/ ° C. Having a coefficient of thermal expansion in this range means that even when heated to temperatures up to 250 ° C,
This means that the length is almost unchanged. And this figure ranges from something close to that of ceramics to something close to that of metals. Such a film having extremely excellent dimensional stability against heat can prevent shrinkage during drying and maintain the plane orientation of molecular chains at a high level.
This is achieved only by increasing the crystallinity by drying or heat treatment at 0 ° C. or higher. Because of having such a small coefficient of thermal expansion, when used at high temperatures, especially as a laminate with ceramics and metals, when used in applications with a high temperature or a large temperature difference, for example, curling does not occur at all, and the characteristics of the film of the present invention Will be exhibited more than enough.

Second, the film used in the present invention has a heat shrinkage at 250 ° C. of 0.1% or less. Thus, since the heat shrinkage of the film used in the present invention is extremely small, it is superior to the polyimide film which currently occupies a large position as a heat resistant film. The heat shrinkage is preferably
0.05% or less. Films with very low heat shrinkage can be subjected to tension-free at temperatures slightly below the drying or heat treatment temperature but above 260 ° C. without substantially reducing the orientation and crystallinity enhanced by the drying or heat treatment. Alternatively, it can be obtained by heat setting the film under low tension.

Third, the film used in the present invention has a coefficient of hygroscopic expansion at 25 ° C. of 30 × 10 ⁻⁶ mm / mm /% RH or less, preferably 20 × 10 ⁻⁶ mm / mm /% RH.
× 10 ⁻⁶ mm / mm /% RH or less. In this way, the feature that the dimensional change due to moisture absorption is small is important for the metallized film to exhibit a certain performance and function regardless of the seasonal difference between hot and humid summer and low humidity dry winter, Such characteristics are achieved by ensuring high crystallinity and orientation by drying or heat treatment at a high temperature.

Further, the film used in the present invention is 25 ° C., 50%
The moisture absorption at RH is 2.5% by weight or less. Such properties are obtained by unique high crystallinity by high temperature drying or heat treatment. Films with a moisture absorption of more than 2.5% by weight have the drawback that they are difficult to process, such as evaporation, and their electrical properties (such as insulation resistance and dielectric constant) fluctuate significantly, reducing their usefulness in electrical applications. Resulting in.

The film used in the present invention should further have a Young's modulus in all directions of 700 kg / mm ² or more, and more preferably 800 kg / mm ² or more in all directions. This feature has implications for dimensional stability against mechanical external forces. Such a large Young's modulus can be easily achieved by performing effective stretching after washing with water and before drying in the production of the film.

As the film used in the present invention, a film having the following characteristics in addition to the above-mentioned essential requirements is preferable.

The film used in the present invention preferably has extremely high transparency. For high transparency, for example, the transmittance of visible light having a wavelength of 600 nm is preferably 55% or more, more preferably 70% or more.

Further, the film used in the present invention is preferably substantially free of voids.

Further, the film of the present invention usually has a density of 1.37.
It is in the range of 0~1.410g / cm ^3. This density value was measured at 30 ° C. by a density gradient tube method using carbon tetrachloride-toluene. Scope of this density is considerably smaller compared to that of known PPTA fibers is from 1.43 g / cm ³ in the range of 1.46 g / cm ^3. If the density is less than 1.370 g / cm ³ , the mechanical properties decrease, and if the density exceeds 1.410 g / cm ³ , the film becomes brittle, and thus the film tends to have reduced toughness. In any case, such a low density results in a light, high-strength film.

As a film used in the present invention, X described below is used.
It preferably has a plane orientation defined by a crystal orientation angle by line diffraction. That is, the crystal orientation angle with respect to the peak of 2θ {23} due to X-rays perpendicularly incident on the film surface is 30 ° or more, and
It is preferable that the crystal orientation angle with respect to the peak of 2θ {18} by a line is 60 ° or less.

The incidence of X-rays is classified into a case where the X-ray is incident on the film surface at a right angle (hereinafter, referred to as a TV direction) and a case where the X-ray is incident on the film in parallel (hereinafter, referred to as an SV direction).

The film of the present invention is 2θ ≒ by X-rays from the TV direction.
Although it has a large diffraction peak at 23 °, the crystal orientation angle at 2θ {23 °} is preferably 30 ° or more.
More preferably, it is 50 ° or more. Further, a large diffraction peak of 2θ ≒ 18 ° appears on the equator line due to incidence from the SV direction, and it is preferable that the crystal orientation angle at 2θ ≒ 18 ° is 60 ° or less. When both of these crystal orientation angles are satisfied, it can be said that the film of the present invention has a so-called plane orientation structure, and high mechanical properties (for example, strength, (Elongation, Young's modulus) and high tear strength. In this regard, the "film" disclosed in Japanese Patent Publication No. 55-14170
Can be clearly distinguished.

As a method of measuring the crystal orientation angle, a known method can be adopted, and for example, the measurement is performed by the following method. The diffraction intensity curve is obtained by placing the counter tube at a predetermined 2θ angle and rotating the film by 180 °. In the case of a TV, it rotates around 90 ° around the maximum intensity. The arc length in the diffractogram, in degrees, corresponding to the point at which the highest intensity of the curve is half the intensity relative to the baseline drawn between the lowest intensity points (ie, 50% of the maximum intensity baseline). Angle with respect to a point) is measured, and this is defined as the crystal orientation angle of the sample. In the measurement, the diffraction intensity can be measured by stacking several films as necessary.

Next, a method for obtaining such a film will be described. To do so, it is necessary first to prepare an optically anisotropic dope of a polymer consisting essentially of PPTA.

A suitable solvent for preparing the dope used to form the film is sulfuric acid at a concentration of 95% by weight or more. With less than 95% sulfuric acid, dissolution is difficult or the dope after dissolution becomes abnormally high in viscosity. The dope of the present invention may contain a small amount of chlorosulfuric acid, fluorosulfuric acid, phosphorus pentoxide, trihalogenated acetic acid, or the like. Sulfuric acid can be 100% by weight or more, but a concentration of 97 to 100% by weight is preferably used from the viewpoint of stability and solubility of the polymer.

The concentration of the polymer in the dope is not less than the concentration exhibiting optical anisotropy at room temperature (about 20 to 30 ° C.) or higher, and specifically, about 10% by weight or more. At a polymer concentration lower than this, that is, a polymer concentration that does not exhibit optical anisotropy at room temperature or higher, the molded film often does not have favorable mechanical properties. The upper limit of the polymer concentration of the dope is not particularly limited, but is usually 20% by weight or less, and particularly preferably 18% by weight or less, particularly preferably 16% by weight or less for a polymer having a high ηinh. .

Dope has common additives such as extenders, delusterants,
An ultraviolet stabilizer, a heat stabilizer, an antioxidant, a pigment, a dissolution aid and the like may be mixed.

Whether the dope is optically anisotropic or optically isotropic can be determined by a known method, for example, a method described in Japanese Patent Publication No. 50-8474, and its critical point is determined by the type of solvent, temperature, and polymer concentration. It depends on the degree of polymerization of the polymer, the content of the non-solvent, etc., so that by examining these relationships in advance, an optically anisotropic dope is produced, and by changing the condition to become an optically isotropic dope, Can be changed from optical to isotropic.

It is preferable that the dope be filtered to remove insoluble dust and foreign matter as much as possible prior to molding and solidification, and to remove gases such as air generated or entrained during melting. Degassing can be performed after the dope is once prepared, or can be achieved by performing a vacuum (reduced pressure) consistently from the stage of charging the raw materials for preparation. The preparation of the dope can be performed continuously or batchwise.

The dope thus prepared is cast onto a supporting surface moving from a die, for example, a slit die, while maintaining optical anisotropy. The steps of casting and the subsequent conversion to optical isotropic, coagulation, washing, stretching, drying, etc., are preferably performed continuously, but if necessary, all or some of them are intermittent, It may be carried out batchwise.

The method of obtaining a transparent film having excellent mechanical properties used in the present invention is to convert the dope from optically anisotropic to optically isotropic prior to solidification after casting the dope on the support surface. .

To make the optically anisotropic from optical anisotropy, specifically, prior to solidification, the optically anisotropic dope cast on the support surface is absorbed to reduce the concentration of the solvent that forms the dope, The dope is transferred to the optically isotropic region by changing the dissolving ability and the polymer concentration, or the temperature of the dope is raised by heating, and the phase of the dope is transferred to the optically isotropic, or the moisture absorption and heating are performed simultaneously or sequentially. It can be achieved by using them together.

In particular, the method using moisture absorption, including the method using heating in combination, is efficient in optical isotropy of optical anisotropy, and PPTA
It is useful because it can be done without causing decomposition of

In order to absorb the dope, air at a normal temperature and humidity may be used, but preferably humidified or heated and humidified air is used. The humidified air may contain water in the form of mist exceeding the saturated vapor pressure, and may be so-called steam. However, supersaturated steam at about 45 ° C. or lower is not preferable because it often contains large granular condensed water. The moisture absorption is usually performed by humidified air at room temperature to about 180 ° C, preferably 50 to 150 ° C.

In the case of the method by heating, the means of heating is not particularly limited, and includes a method of applying the humidified air to the casting dope, a method of irradiating an infrared lamp, a method of dielectric heating, and the like.

The casting dope optically isotropic on the support surface then undergoes solidification. The coagulating liquid of the dope can be, for example, water, about 70% by weight or less of dilute sulfuric acid, about 20% by weight or less of sodium hydroxide aqueous solution and ammonia water, about 10% by weight or less of sodium sulfate, sodium chloride aqueous solution and chloride. Calcium aqueous solution and the like.

The temperature of the coagulation liquid is preferably 15 ° C. or lower, more preferably 5 ° C. or lower. This is because it has been generally found that the lower the coagulating liquid temperature, the smaller the voids contained in the film.

Since the coagulated film contains an acid as it is, it is necessary to wash and remove the acid component as much as possible in order to produce a film with less decrease in mechanical properties due to heating. Specifically, it is desirable to remove the acid content to about 500 ppm or less. Water is usually used as the washing liquid, but if necessary, washing may be performed with warm water, or after neutralizing and washing with an alkaline aqueous solution, washing with water or the like. The cleaning is performed by, for example, running the film in the cleaning liquid or spraying the cleaning liquid.

The washed film then undergoes drying. Drying, ie, placing the film under no tension with a decrease in moisture generally causes the film to shrink, but in obtaining the film used in the present invention, it is important that the film is not shrunk in the drying step. Here, the expression “no shrinkage” should be understood to include two types: drying with a fixed length and drying while stretching.
Then, for example, a mode in which the film is stretched in only one direction and the other direction is kept at a fixed length is also allowed. It is also important to select a drying temperature, either at an ambient temperature of 300 ° C or higher (T ₁ ° C), or once at an arbitrary temperature, then 300 ° C.
The heat treatment is performed at the above temperature (T ₁ ° C) without shrinkage. Here, drying means removing water from the film, and changing the physical structure (for example, crystalline state) of the film thereafter is called heat treatment. In any case, it is necessary to perform the fixing of the structure under tension at 300 ° C. or higher temperature T _1, thereby reducing the thermal expansion coefficient and hygroscopic expansion coefficient, it is possible to suppress moisture absorption.

After drying or heat treatment at a temperature T ₁ (° C.) of 300 ° C. or more, 0 to 0.8 kG / mm ² at T ₂ (° C.) satisfying 260 ≦ T ₂ ≦ T ₁ -20
It is also important to perform the heat treatment under no tension or low tension. This means that the so-called heat fixation is performed under substantially no tension, and the heat fixation can reduce the heat shrinkage rate and can secondarily improve the tear resistance.

To perform drying and heat treatment without causing the above shrinkage,
For example, by placing it in an oven sandwiched between a tenter or a metal frame, and drying under relaxation or low tension, place it in an oven at the free end, or set the tenter to a fixed length and raise the temperature to about 50%. ℃ (that is, T ₁ −T ₂ ≧
50 (° C.)), a method of slightly narrowing the tenter gripping interval, and the like. Other conditions relating to drying and heat treatment are not particularly limited, such as a method using a heating gas (air, nitrogen, argon, etc.) or a normal temperature gas, a method using radiant heat such as an electric heater or an infrared lamp, and a dielectric heating method. It is one of the preferred embodiments that the film can be produced by running the film continuously throughout the entire process, although the method can be freely selected from the means, but if desired, it can be performed partially batchwise. Further, an oil agent, a dye for identification, or the like may be applied to the film in an optional step.

In the present invention, in order to obtain a film having excellent transparency, that is, a film having an extremely large light transmittance, it is obvious that the dope is not limited to a gas for absorption of moisture, a gas for heating, a support surface, a coagulating liquid, a cleaning liquid, a dry gas, etc. It is preferable to reduce the content of refuse and dust as much as possible. In this regard, it is also a preferable embodiment to manufacture a film using so-called clean room or clean water.

In the film of the present invention, for example, silica as a smoothing agent,
Inorganic substances such as talc and calcium sulfate may be dispersed and contained.

Further, prior to the formation of the magnetic recording layer described below, the film used in the present invention may be subjected to various surface treatments and pretreatments for the purpose of easy adhesion, improvement of flatness, coloring, antistatic, and imparting abrasion resistance. May be applied.

Next, a method for producing a metal thin film and a metallized film will be described.

The type of metal in the metal thin film of the present invention is not particularly limited, and is appropriately used depending on the use of the metallized film. For example, for magnetic recording media, Co, Ni, Cr,
Fe and their alloys, such as Co-Cr alloy, Co-Ni alloy, Co-Ni-Fe alloy, Co-Fe alloy, oxides of Co (such as CoO), and a small amount of P, Si, Alloys with B, Mn, Zn, etc., iron oxides, iron nitrides, iron hydroxides, iron sulfides, iron carbonate compounds, etc. Specifically, iron oxides are Fe
O, and the like _{Fe 2 O 3, Fe 3 O} 4, as the iron nitride Fe ₂ N, F
e ₄ N, etc., and iron hydroxides such as Fe (OH) ₂ , Fe (O
H) ₃ , FeOOH, etc., and iron sulfides such as FeS, Fe ₂ S ₃
FeCO ₃ , FeCO ₃ .H ₂ O
And so on. Also, non-stoichiometric iron compounds having intermediate compositions other than those described herein are included. In addition, for capacitors, there are aluminum, zinc, iron, titanium, nickel, and alloys thereof, but are not limited thereto.

Further, for a transparent conductive film, indium oxide, tin oxide, cadmium oxide, antimony oxide, zinc oxide, tungsten oxide, molybdenum oxide, or a mixture thereof, gold, palladium, or chromium-based alloy is used. In addition, any metal such as silver, copper, tantalum, titanium, and titanium nitride may be used as needed.

The method for depositing these metal thin films on the film may be a known method, for example, vacuum deposition, ion plating, sputtering, chemical vapor deposition, laser chemical vapor deposition, plasma deposition, deposition by plating. Method, an electroless plating method, or an appropriate combination thereof.

The thickness of the metal thin film is usually 50 to 50,000 °, preferably 50 to 10,000 °.

〔Example〕

Examples are shown below, but these reference examples and examples are for explaining the present invention and do not limit the present invention. Unless otherwise specified in the examples, parts or parts by weight are indicated.

 The evaluation of each characteristic in the examples was performed by the following methods.

The logarithmic viscosity η inh was determined by dissolving 0.5 g of the polymer in 100 ml of 98% sulfuric acid and measuring at 30 ° C. by a conventional method.

The elongation and Young's modulus were measured using a constant-speed elongation type elongation meter to cut a film sample into a rectangle of 100 mm × 10 mm, and the initial gripping length was 30 mm, and the tensile speed was 30 mm / min.
The elongation curve was drawn five times and calculated from this.

The expansion coefficient was measured using a thermomechanical analyzer, 5 mm in width,
The test was performed by applying a load of 0.05 kg / mm ² to a sample having a length between the gripping portions of 15 mm. In the case of the thermal expansion coefficient, the dimensional change of the sample was measured between 25 and 250 ° C, and the rate of change between 25 and 250 ° C was calculated by dividing by 225. On the other hand, in the case of the coefficient of hygroscopic expansion, the humidifier was first kept at 20% relative humidity at 25 ° C., and then humidified from a humidifier until the relative humidity increased to 80%. .

Moisture absorption was calculated from the weight of the film measured by allowing the film to stand at 25 ° C. and 50% relative humidity for 48 hours and the weight of the film obtained by drying the film in a vacuum dryer at 120 ° C. until a constant weight was reached. .

The heat shrinkage at 250 ° C. is calculated from a dimensional change at room temperature (25 ° C.) before and after the oven treatment, after applying a tension of 0.05 kg / mm ² and leaving the plate in an oven at 250 ° C. for 30 minutes.

Examples 1 to 5 and Comparative Examples 1 to 4 A PPTA polymer having a η inh of 5.5 was dissolved in 97.7% sulfuric acid at a polymer concentration of 12.5% to obtain a dope having optical anisotropy at 60 ° C. When the viscosity of this dope was measured at room temperature, it was 11,5
It was 00 poise. In order to facilitate film formation, the dope was degassed under vacuum while maintaining the dope at about 70 ° C. Also in this case, it had the same optical anisotropy as above, and the viscosity was 4,800 poise. Keep the 1.5m curved pipe from the tank through the filter, through the gear pump to the die at about 70 ° C, cast from a die with a slit of 0.1mm x 300mm to a mirror-polished tantalum belt, and adjust the relative humidity. The casting dope was optically isotropic by blowing about 12% of air at about 105 ° C., and was introduced into water at 5 ° C. with a belt to solidify. Next, the coagulated film is peeled off from the belt, and warm water of about 30 ° C., and then 0.5% N
Washing was performed by running water at room temperature in the aOH aqueous solution.
The film after washing was stretched 15% each in the length direction and the width direction by a tenter without drying, and then dried with a different tenter at 370 ° C. under a constant length at 370 ° C. Further, the film is guided to a third tenter, and the clip-shaped grip portion is adjusted so that the grip length in the width direction and the length direction is reduced by 5% each, and heat treatment is performed at the temperature shown in Table 1 (heat fixing).
did. Tension in the third tenter was in the range of 0~0.3kg / mm ^2.

The resulting film has a thickness of 14 μm, ηinh 5.0 to 5.2,
It was between density 1.390~1.405g / cm ^3. Other properties are shown in Table 1.

The films obtained in Examples 1 and 3 were loaded into a vacuum chamber and glowed under an atmosphere of Ar at 10 ^-2 Torr, then the vacuum chamber was evacuated to 10 ^-6 Torr, and the film was heated to 100 ° C.
While running along a heated drum, a Co-Ni alloy was deposited to a thickness of 1200 ° by electron beam evaporation to obtain a metallized film of the present invention.

This was slit into a magnetic tape, evaluated by the following method, and the results are shown in Table 2.

Runnability: Using a VHS video tape recorder, screen fluctuations due to tape running were observed. Atmosphere is 25 ℃, 65
% RH.

Note: In the table, the values excluding the moisture absorption rate indicate the average values in the length direction and the width direction, and the difference in the physical property values depending on the direction was within 8%.

：: The running performance was good and there was no fluctuation in the playback screen.

X: Running performance deteriorated, and the reproduction screen fluctuated.

Durability: Scratches on the magnetic surface, wrinkles of the missing tape, and breakage after running 100 times were observed. Atmosphere is 25 ℃, 55%
It is under RH.

◎: No scratches, missing parts, wrinkles, or breaks.

：: Extremely weak scratches and wrinkles are observed.

X: Severe scratches, missing wrinkles and breaks in the magnetic layer are observed.

Dropout: Video recording was performed, the dropout of the video output during playback was 18 dB, and the dropout with a duration of 20 seconds or more was measured with a dropout counter for 10 minutes, and the relative comparison was made.

Heat resistance: left at 85 ° C. and 30% RH for 24 hours, and observed whether or not curl or the like occurred.

Then, using the same electron beam evaporation equipment, about 1800Å
A ferromagnetic layer composed of cobalt and cobalt oxide having a thickness of 3 mm was formed on the PPTA films of Examples 2 and 4 to obtain a metallized film of the present invention.

This was also slit into a magnetic tape, and the results evaluated by the above method are shown in Table 2.

Further, the same vapor deposition as in Example 1 was performed on the PPTA films of Comparative Example 1 and Comparative Example 2, and slit to obtain a magnetic tape. Table 2 shows the characteristics of these tapes. It is considered that the cause of the poor heat resistance is that the coefficient of thermal expansion is large (Comparative Example 2) and the coefficient of thermal expansion is negative (Comparative Example 1). Was.

Next, a magnetic tape was produced in the same manner as in Example 1 using 12.5 μ of a commercially available polyimide film. Table 2 shows the results of evaluation of the base film as a magnetic tape (Comparative Example 3).

Further, vapor deposition was attempted in the same manner as in Example 1 using a polyethylene terephthalate film, but the film was deformed or perforated, and a vapor deposited film could not be obtained (Comparative Example 4).

Then, a mixture of indium oxide and 7.5% by weight of tin oxide was vacuum-deposited on the film of Example 5 in Table 1.
The resulting film is a low oxide of indium metal,
Film thickness 350mm, surface resistance 6KΩ / cm ² , transmittance of light of 600nm about 38
% Of the conductive film.

Even if this deposited film is heated at 300 ° C for 30 minutes,
Even after heating at 00 ° C. for 2 hours, no change in performance and no curling were observed.

Example 6 On a film of Example 5 shown in Table 1, a Co-Ni alloy was laminated to a thickness of 2500 ° by sputtering, and this was slit into a magnetic tape, and as a result evaluated by the above method, Good tape properties were obtained for all items.

Example 7 In Example 4 of Table 1, a 4.5 μm-thick PPTA film was obtained by adjusting the ratio of the speed at which the dope was discharged from the die to the speed at which the belt was moved during the production of the PPTA film. Except for the thickness, this film was identical to the film of Example 4 in Table 1 except for the measurement error.

In this embodiment, an example of manufacturing a metallized film for a perpendicular magnetic recording medium from the PPTA film thus obtained will be described.

The inside of the vacuum chamber of the semi-continuous electron beam evaporation apparatus is evacuated to 1 × 10 ⁻⁵ Torr or less by an exhaust system. Then, as a gas to be introduced, a mixed gas balanced with 20% by volume of oxygen and the balance of nitrogen was introduced through a variable leak valve until the pressure in the vacuum chamber became 2 × 10 ⁻³ Torr, and the above-mentioned PPTA film was about 2 m / min. , And a ferromagnetic layer of iron and iron compound having a thickness of about 2000 mm was continuously formed by electron beam evaporation. In addition, an unwinding roll, a cooling drum, and a film traveling system including a winding roll are provided in the vacuum chamber of the apparatus, and an electron beam evaporator having a concave portion immediately below the cooling drum is provided. A shielding plate having an opening such that the incident angle to the cooling drum is 16 degrees or less,
Placed close to the cooling drum.

The obtained magnetic recording medium (metalized film) has a perpendicular coercive force of 970 Oe and a perpendicular anisotropy magnetic field of 3.9 KOe, and these characteristics almost change even when left in an oven at 160 ° C. for 8 hours. Did not.

Further, the magnetic anisotropy coefficient of the magnetic recording medium before it was placed in the oven was 2.1, that is, it was confirmed that the magnetic recording medium had an easy axis of magnetization larger than 1.0 and perpendicular to the substrate surface. As a result of the composition analysis of the ferromagnetic layer, the main component of the ferromagnetic layer was
It was found that it was composed of Fe, Fe ₂ O ₃ , Fe ₃ O ₄ , and Fe (OH) ₂ .

Next, using the same semi-continuous electron beam evaporation apparatus, the traveling system in which a shielding plate having an opening in which the incident angle of the evaporation vapor flow to the cooling drum is 16 degrees or less is provided, With the PPTA film disposed and cobalt disposed in the recess of the electron beam vaporizer, the vacuum chamber of the vacuum vapor deposition apparatus is evacuated to 1 × 10 ^-5 Torr or less by an exhaust system, and then oxygen gas is variable. With the PPTA film running at a speed of about 3 m / min in an atmosphere introduced through a leak valve until the pressure in the vacuum chamber becomes 3 × 10 ⁻⁴ Torr,
A ferromagnetic layer composed of cobalt and cobalt oxide with a thickness of about 1800Å was formed on the PPTA film by electron beam evaporation. The perpendicular coercive force is 1040 Oe, the perpendicular anisotropy field is 4.5 KOe, the magnetic anisotropy coefficient is 1.8, and it is a perpendicular magnetic recording medium (metallized film) having an easy axis of magnetization perpendicular to the substrate surface. Was.

The analysis also revealed that the ferromagnetic layer contains Co and CoO as main components.

Example 8 PPTA with ηinh of 4.8 was converted to 99.5% sulfuric acid containing SiO ₂ by 12
%, And a dope containing about 0.05% by weight of 3600 poise dispersed SiO ₂ having optical anisotropy at 45 ° C. was obtained. After deaeration and filtration, the dope was cast on a tantalum belt from a die having a slit of 0.08 mm × 300 mm. The casting dope was converted to a transparent optically isotropic dope by blowing air at about 75 ° C. at a relative humidity of about 80%, and then coagulated with a 10% aqueous sulfuric acid solution at 0 ° C. After peeling the coagulated film from the belt, water at room temperature, 2% aqueous caustic soda, about 30-40 ° C
Of water.

The wet film that has been washed and contains about 250-350% water is stretched 1.2 times to MD and 1.25 times to TD in a tenter,
The film was dried under a fixed length in a tenter in which hot air at a temperature of circulating was circulated. Next, the film was guided to a heat treatment tenter whose temperature was adjusted to 300 to 310 ° C., and the film was run and shrunk by 3% in MD and TD, and heat-fixed.

The obtained film has a thickness of 2.0 μm, ηinh4.4, density
1.401g / cm ³ , strength 27kg / mm ² , elongation 17%, Young's modulus 1120kg
/ mm ² , moisture absorption 0.9%, thermal shrinkage 0.01% or less, thermal expansion coefficient 1
The film had isotropic properties of 4 × 10 ⁻⁶ mm / mm / ° C. and a coefficient of hygroscopic expansion of 11 × 10 ⁻⁶ mm / mm /% RH.

The obtained PPTA film was set in an electron beam vacuum vapor deposition device, and aluminum was vapor-deposited so as to have a film resistance of 4 / port to obtain a metallized film. This vapor-deposited film was slit (6 mm width) and wound on an element winding machine to form a capacitor element. Further, the end face was sealed and a lead wire was attached by a conventional method to produce a capacitor.

For comparison, a metallized film capacitor was similarly formed from a polyethylene terephthalate (PET) film having a thickness of 2 μm, and in the process, the advantages of the metallized film of the present invention became clear.

That is, since the strength and Young's modulus of the PPTA film used in this example are much larger than the PET film,
Despite its thickness of 2 μm, it was stiff and easy to deposit. This ease of vapor deposition is related to the fact that PPTA film has high strength and Young's modulus even at high temperatures,
It was further expanded by the ability to apply high tension. The PPTA film used in this example had a coefficient of thermal expansion close to that of aluminum and a small coefficient of hygroscopic expansion, so that the metallized film did not curl. Furthermore, because of the low thermal shrinkage, no change occurred when the capacitor was immersed in a solder bath.

〔The invention's effect〕

Since the metallized film of the present invention has no difference in dimensional stability with respect to temperature and humidity between the metal thin film layer and the base film, the metalized film is placed in a high-temperature solder bath (250 ° C. or higher) or a reflow solder atmosphere (240 ° C. or higher). Also, even when placed in a high-temperature atmosphere, for example, in a closed automobile in summer, the change in performance is significantly smaller than that of a conventionally known metallized film. Further, since the moisture absorption rate is small, there is a feature that the adhesive force between the metal thin film and the film is large based on the chemical affinity of the polymer substantially consisting of PPTA. In addition, the unique properties of the base PPTA-based film, such as high strength, high Young's modulus,
Excellent electrical insulation, heat resistance, oil resistance, pressure resistance, chemical resistance other than strong acid, dense structure, etc. are also maintained in the metallized film. Due to these characteristics, the metallized film of the present invention is useful as a magnetic recording medium, a transparent conductive film, a capacitor, a heat-resistant gas barrier film, a flexible printed board, a carrier tape, and the like.

Claims (1)

(57) [Claims] 1. A film comprising a para-oriented aromatic polyamide having a logarithmic viscosity of 3.5 or more, having a coefficient of thermal expansion from 25 ° C. to 250 ° C. (0 to 15) × 10 ⁻⁶ mm / mm / ° C., The heat shrinkage at 0.1 ° C is 0.1% or less, the coefficient of moisture expansion at 25 ° C is 30 × 10 ^-6 mm / mm /% RH or less, the Young's modulus in all directions is 700kg / mm ^-6 or more, and 25 ° C, 50% Moisture absorption rate at RH
A metallized film having a metal thin film on at least one surface of the film, which is not more than 2.5% by weight.