JPH11245291A - Aromatic polyamide film and solar cell using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce surface faults with a flat surface of an aromatic polyamide film by forming the film having a specific heat shrinkage factor and slack amount, thereby utilizing high rigidity and heat resistance. SOLUTION: The aromatic polyamide film has 21 or less of a heat shrinkage factor in a width direction at 210 deg.C. If the factor is less than 28, the film is deformed by a heat in the case of attaching an amorphous silicon thin film, and hence a good film is not obtained. A slack amount of the film at a center is 60 mm in the case of applying a load of 0.5 kg/mm<2> to the film having a width of 610 mm and a length of 2 m. If the slack amount is less than 60 mm, the film is released from a support on the support such as a drum in the case of providing the silicon thin film, the film is deformed by the head or a contact with a guide roll is deteriorated at the time of feeding the film, and hence there occurs a problem in which a damage is formed on the film. The solar cell having the silicon thin film on the polyamide film is flat and has excellent film characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyamide film having good flatness and a solar cell having an amorphous silicon thin film provided thereon.

[0002]

2. Description of the Related Art Aromatic polyamide films have been studied for various applications by utilizing their excellent heat resistance and mechanical properties. In particular, para-oriented aromatic polyamides have excellent mechanical properties such as rigidity and strength compared to other polymers, and are therefore very advantageous for thinning films or improving the strength of film base materials, such as printer ribbons, magnetic tapes, Used for applications such as capacitors and solar cells.

[0003] For example, JP-A-7-135330,
JP-A-7-135331 describes a solar cell in which an aromatic polyamide film is used as its substrate and an amorphous silicon thin film is provided thereon. A flexible solar cell can be obtained by using the film as a substrate, Its application range is wide. Such a solar cell is usually manufactured by unwinding a film continuously from a roll and continuously vacuum-depositing and sputtering necessary layers such as an amorphous silicon layer on the film.

[0004]

However, in the above-mentioned conventional method, the film is heated to a temperature of 200 to 350 ° C. or the like, so that the film is deformed by heat or floats from the cooling drum due to poor flatness of the film. The film is thermally deformed,
There was a problem that good flatness could not be maintained. In addition, there is a problem that running properties are uneven due to poor flatness, and scratches are caused to deteriorate film characteristics.

An object of the present invention is to solve the above problems and to provide an aromatic polyamide film which is flat and has few surface defects by utilizing the excellent high rigidity and heat resistance of the aromatic polyamide, and a solar cell using the same. It is assumed that.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a film having a heat shrinkage of 210% or less in the width direction (hereinafter referred to as TD direction) of 2% or less, and a film having a width of 610 mm and a length of 2 m. An aromatic polyamide film characterized in that the film thickness at the center when a load of 0.5 kg / mm ² is applied to the film is 60 mm or less, and an amorphous silicon thin film is provided on the aromatic polyamide film. Can be achieved by a solar cell.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the aromatic polyamide contains a repeating unit represented by the following general formula (I) and / or (II) in an amount of 50 mol% or more, more preferably 70 mol% or more. Are preferably mentioned.

Formula (I) General formula (II) Here, as Ar ₁ , Ar ₂ and Ar ₃ , for example, And the like, X, Y _{are, -O -, - CH 2 -} , - CO -, - SO 2 -, -S-,
—C (CH ₃ ) ₂ — and the like, but is not limited thereto.
Further, some of the hydrogen atoms on these aromatic rings may be substituted with a substituent such as a halogen group (especially chlorine), a nitro group, a C ₁ -C ₃ alkyl group (especially a methyl group), or a C ₁ -C ₃ alkoxy group. And those in which the hydrogen in the amide bond constituting the polymer is substituted by another substituent. From the viewpoint of characteristics, those in which the above aromatic rings are bonded at the para position are 50% or more, preferably 7%, of all aromatic rings.
A polymer occupying 0% or more is preferable because the film has high rigidity and good heat resistance. Further, from the viewpoint of reducing the moisture absorption, a polymer in which a part of hydrogen atoms on the aromatic ring is substituted with a halogen group (particularly chlorine) and the aromatic ring is 30% or more of the whole is preferable.

More preferred specific examples of the aromatic polyamide include: (Where m and n are from 0 to 4) in an amount of 50 mol% or more, more preferably 70 mol% or more.

[0010] As other components contained in the aromatic polyamide, other repeating units such as aromatic polyimide may be copolymerized in an amount of less than 50 mol%, or blended with other polymers, or the physical properties of the film may be impaired. To a small extent, conductive particles, lubricants, antioxidants and other additives may be blended.

The aromatic polyamide film of the present invention has the following properties:
The heat shrinkage in the TD direction at 10 ° C. needs to be 2% or less. Preferably it is 1% or less. If it is more than 2%, the film is deformed by heat when the amorphous silicon thin film is applied, and a good film cannot be obtained.

The aromatic polyamide film of the present invention is 0.5 kg / mm to a 610 mm wide and 2 m long film.
^When a load of ² is applied, the thickness of the film at the central portion needs to be 60 mm or less. Preferably it is 30 mm or less. If the thickness is larger than 60 mm, when the amorphous silicon thin film is provided, the film separates from the support on a support such as a drum, and there is a problem that the film is deformed by heat. Further, when the film is run, the contact with the guide roll is poor, and there is a problem that the film is damaged.

The thickness of the aromatic polyamide film of the present invention is preferably in the range of 2 μm to 150 μm. More preferably, it is 2 μm or more and 100 μm or less.

The aromatic polyamide film of the present invention preferably contains particles in the film in order to maintain the surface roughness and the coefficient of friction. The types of particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CaSO ₄ , BaS
There are inorganic particles such as O ₄ , CaCO ₃ , carbon black, zeolite, and other fine metal powders, and organic polymers such as silicon particles, polyimide particles, cross-linked copolymer particles, cross-linked polyester particles, and Teflon particles. However, inorganic particles are more preferable from the viewpoint of heat resistance. The particle size is 0.
The range is from 0.01 to 5 μm, and more preferably from 0.05 to 2 μm. The content is preferably from 0.005 to 10 wt%, more preferably from 0.01 to 5 wt%.

Particularly, the ten-point average roughness Rz of the surface on which the silicon thin film is provided is preferably 1 to 200 nm. More preferably, it is 2 to 100 nm. Further, by appropriately controlling the friction with the guide roll, the drum, and the like, the contact property can be improved and the traveling can be stabilized.

The Young's modulus of the aromatic polyamide film of the present invention is 700 kg / mm ² or more in the film length direction (hereinafter referred to as MD direction) and 800 in the TD direction.
kg / mm ² or more, more preferably 1000 in the TD direction.
It is preferably kg / mm ² .

The elongation of the aromatic polyamide film of the present invention is preferably 10% or more, more preferably 20% or more, and still more preferably 30% or more, from the viewpoint of appropriate flexibility.

The aromatic polyamide film of the present invention preferably has a moisture absorption of 4% or less, more preferably 3% or less.
More preferably, it is at most 2%. The smaller the moisture absorption, the smaller the generation of water at a high temperature, which is preferable in that the characteristics of the amorphous silicon thin film are improved.

Next, the method for producing the aromatic polyamide film of the present invention will be described with reference to an example.

First, when the aromatic polyamide is obtained from an acid chloride and a diamine, N-methylpyrrolidone (N
MP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other aprotic organic polar solvents, and is synthesized by solution polymerization or interfacial polymerization using an aqueous medium. When acid chloride and diamine are used as monomers in a polymer solution, hydrogen chloride is produced as a by-product, but when neutralizing this, inorganic chlorides such as calcium hydroxide, lithium hydroxide, calcium carbonate, and lithium carbonate are used. A wetting agent, ethylene oxide, propylene oxide,
Organic neutralizers such as ammonia, triethylamine, triethanolamine, diethanolamine and the like are used. The reaction between the isocyanate and the carboxylic acid is performed in an aprotic organic polar solvent in the presence of a catalyst.

In order to obtain the aromatic polyamide film of the present invention, the intrinsic viscosity of the polymer (measured at 30 ° C. as a 100 ml solution of 0.5 g of the polymer in sulfuric acid) is as follows:
It is preferably 0.5 or more.

The above polymer solution may be used directly as a stock solution for film formation, or the polymer may be isolated once and then redissolved in the above organic solvent or inorganic solvent such as sulfuric acid to prepare a stock solution for film formation. You may.

In the case of preparing a stock solution by redissolving,
Inorganic salts such as calcium chloride, magnesium chloride, lithium chloride and lithium nitrate may be added as a dissolution aid. At this time, the polymer concentration in the film forming stock solution is 2 to 40.
wt% is preferred.

In order to maintain the surface roughness and the coefficient of friction of the film as described above, when particles are contained, the particles are preliminarily slurried in a solvent and then used as a polymerization solvent or a dilution solvent. They can be used directly or added directly after preparing a membrane-forming stock solution.

The stock solution thus prepared is formed into a film by a so-called solution casting method. The solution film forming method includes a dry-wet method, a dry method, a wet method and the like, and the film may be formed by any method. Here, the dry-wet method will be described as an example.

First, a stock solution is extruded from a die onto a support such as a drum or an endless belt made of a material such as nickel, stainless steel, copper, titanium, hastelloy, or tantalum to form a thin film, and then the solvent is scattered from the thin film layer. The film is dried until it has a self-holding property. Drying conditions are preferably in the range of room temperature to 250 ° C and within 60 minutes, more preferably in the range of room temperature to 200 ° C. Drying temperature is 250 ℃
If the temperature exceeds the limit, voids are generated due to rapid heating, the surface is roughened, and a practical film cannot be obtained.

The film after the dry process is peeled off from the support and introduced into the wet process, where the solvent and impurities contained in the film are removed. The bath used in the wet process includes an aqueous medium, and may contain an organic solvent, an inorganic salt, or the like in addition to water. In particular, it is preferable to contain 30% or more, more preferably 50% or more of water, and it is preferable to use the bath at a temperature of 0 to 100 ° C.

The film after the wet process is further dried and stretched. Drying and stretching are performed at room temperature to 400 ° C., and the stretching ratio is 0.8 to 5.0 (area ratio) is defined as a value obtained by dividing the area of the film after stretching by the area of the film before stretching. Means relaxation.) A more preferred stretching ratio is 1.1 to 3.0. Depending on the type of polymer, it is better to stretch in a water-containing state, and the stretching may be performed at 80 ° C. or lower, which is close to room temperature.

Particularly, in order to obtain the heat shrinkage and the amount of tarmi necessary for the aromatic polyamide film of the present invention, for example,
In the case of an aromatic polyamide film having a water content of 30 to 70%, the tenter temperature is set to 250 ° C. or higher, more preferably 25 ° C.
The temperature is preferably set to 5 ° C. or higher.

In order to improve the flatness in the TD direction, T
It is preferable to maintain the stretching temperature unevenness in the D direction at 2% or less of the average temperature.

After the stretching, the film is cooled to room temperature to obtain the aromatic polyamide film of the present invention. By setting the temperature unevenness in the TD direction at this time to 15% or less, the flatness of the film, which is the object of the present invention, can be easily obtained.

Next, a solar cell using the aromatic polyamide film will be described.

A solar cell is composed of the aromatic polyamide film and an amorphous silicon thin film provided on the film. The configuration of the amorphous silicon thin film is not particularly limited.
To 50 μm, an amorphous silicon layer is provided thereon, and an electrode is further provided thereon.

Hereinafter, a specific method for manufacturing a solar cell by providing an amorphous silicon thin film on an aromatic polyamide film will be described with reference to an example.

First, a conductive layer having a thickness of 0.01 to 50 μm is formed on an aromatic polyamide film. The conductive layer is a simple substance of stainless steel, nickel chromium alloy, nickel, iron, chromium, niobium, titanium, zirconium or their alloy,
Alternatively, the oxide semiconductor layer can be formed by vapor deposition or sputtering of an oxide such as tin oxide, indium oxide, indium tin oxide, or cadmium oxide. Before forming the conductive layer,
In order to improve the adhesion between the aromatic polyamide film and the conductive layer, it is preferable to perform a corona treatment, a glow treatment or the like.

Next, an amorphous silicon layer is formed by a method such as a glow discharge method, a sputtering method, or an ion plating method.

For example, in the case of the glow discharge method, 10 to 0.
The aromatic polyamide film wound on a roll was drawn out in a vacuum reactor maintained at 001 Torr, and then pulled from 200 to 35.
Run on a support electrode heated to 0 ° C. While sending SiH ₄ gas into the vacuum reactor, a voltage is applied between the electrode facing the support electrode and a discharge is generated, and the inside of the vacuum reactor is turned into a plasma state, whereby SiH ₄ is decomposed and becomes amorphous on the film. A silicon layer is formed. At this time,
If B ₂ H ₆ is sent together with iH ₄ , a p-type amorphous silicon layer is formed, and if PH ₃ is sent together with SiH ₄ , an n-type amorphous silicon layer is formed.

Thereafter, for example, in the case of a Schottky junction cell, a Schottky barrier electrode having a thickness of about 10 nm can be formed by sputtering or vacuum depositing platinum, gold, palladium or the like. In the case of a hetero-coupled cell, a hetero electrode having a thickness of 10 to 500 nm can be formed by sputtering or vacuum depositing indium oxide, tin oxide, indium tin oxide, and cadmium oxide.

Further, a solar cell can be obtained by providing a collecting electrode made of palladium or the like on the Schottky barrier electrode or the hetero electrode.

The solar cell obtained in the present invention has a photoelectric conversion characteristic of 5% or more.

Hereinafter, the present invention will be described specifically with reference to examples.

In the present invention, a method for measuring physical properties and a method for evaluating effects are as follows.

(1) Heat Shrinkage A sample long in the TD direction is cut out so as to have a width of 10 mm and a length of 250 mm, and mark lines are drawn at 200 mm intervals.
After heating this in an oven at 210 ° C. for 10 minutes, the film is taken out and the interval between the marked lines is measured. The shrinkage is determined from the dimensions before and after heating.

(2) Ten-point average roughness Rz A stylus tip radius of 0.5 μm, a stylus load of 5 mg, a cut-off value of 0.008 mm, and a measurement length using a thin film level difference measuring device (ET-10) manufactured by Kosaka Laboratory. The measurement was performed five times under the condition of 0.5 mm, and the average value was expressed.

(3) Talmi amount The measurement method will be described with reference to FIGS. That is, FIG.
As shown in the figure, the width of the film 1 in the TD direction is 610 mm.
And prepare it for 2 m or more in the MD direction. The film is transferred to two rolls 3 at a distance of 2 m, and a load of 0.5 kg / mm ² is applied in the MD direction. 2
The thread 2 is passed in parallel with the roll 3 to the center of the book roll, the thread is wound so as to be in contact with the film, and the distance between the thread 2 and the film 1 at the most slack position is measured as shown in FIG. Ask for. The measurement was performed at a temperature of 25 ° C. and a humidity of 50% RH.
Under the environment.

(4) Photoelectric conversion characteristics The conversion efficiency was measured with a solar simulator manufactured by Oriel and adjusted to AM = 1.

(5) Young's modulus and elongation Measured using an Instron type tensile tester.
The test piece is 10 mm wide and 50 mm long, and the tensile speed is 30
0 mm / min.

(6) Moisture absorption rate An oven adjusted to a temperature of 25 ° C. and a humidity of 75% RH
A completely dried test piece of 0 cm × 10 cm was put in, taken out two days later, and weighed.

[0049]

Example 1 A polymerization vessel was charged with N-methyl-2-pyrrolidone (NMP), and 2-chloroparaphenylenediamine corresponding to 80 mol% as an aromatic diamine component and 4,20 mol% of 4, 4′-Diaminodiphenyl ether was dissolved. To this was added 2-chloroterephthalic acid chloride corresponding to 99.5 mol% to complete the polymerization.
Further, 97 mol% of the generated hydrogen chloride was neutralized with lithium carbonate, and then 10 mol% of ammonia was added to obtain a polymer solution.

The primary particle size was 0.02 μm in NMP.
A slurry in which m particles of silica were dispersed to an average particle size of 0.2 μm was added so that the amount of particles was 0.3 wt% with respect to the polymer. And polymer concentration 10.7wt%, 30
The solution viscosity at ℃ was adjusted to 4000 poise to obtain a stock solution.

This was kept at 40 ° C. and passed through a filter having a cut of 3 μm, and then cast from a die onto a metal belt so that the final film thickness became 20 μm. The cast film was heated with hot air at 130 ° C. to evaporate the solvent, and the film having self-holding property was continuously peeled off from the belt. Next, the film was introduced into the water tank to extract the residual solvent and the inorganic salts generated by the neutralization. MD in a water / NMP mixed bath at 50 ° C (ratio 90 / 10wt%)
The film was stretched 1.1 times in the direction, and further sufficiently extracted with water.

Next, it was introduced into a tenter and dried, stretched and heat-treated at 300 ° C. During this time, the film TD
The film was stretched 1.3 times in the direction. T of the stretched part at this time
The temperature unevenness in the direction D was 2 ° C. (0.7% of the average temperature). This was then cooled to a room temperature of 25 ° C. at the outlet of the tenter.
Met. The portion having the largest unevenness had an unevenness of 2 ° C. at an average temperature of 25 ° C. near the exit of the tenter. The Young's modulus of the obtained film is 1150 kg / m in the MD direction.
m ² , and TD direction was 1250 kg / mm ² . Table 1 shows the heat shrinkage in the TD direction of the film and the thickness of the film. The ten-point average roughness Rz was as smooth as 32 nm.
The elongation was 52% and 45% in both the MD and TD directions, and the moisture absorption was 1.5%.

Using a stainless steel target with a sputtering device, a thickness of 1
A 00 nm stainless steel layer was formed.

Next, the above film was set on the supporting electrode in the vacuum reactor, the inside of the reactor was once evacuated to 10 ^-5 Torr, and the temperature of the supporting electrode was raised to 200 ° C. argon gas was introduced into the vessel and pre-sputtered under 1Torr an argon atmosphere while applying a 15MHz high frequency voltage of 30 W, and then SiH ₄ diluted to 10% with hydrogen gas, similarly diluted to 1% with hydrogen gas Done P
An H ₃ gas was introduced, and a 25 nm n-type amorphous silicon layer was formed on the film under an atmosphere of 1 Torr.
Subsequently, an i-type amorphous silicon layer having a thickness of 500 nm is laminated by introducing only SiH ₄ , and a layer containing 1% B ₂ H ₆ in SiH ₄ gas is introduced, and a thickness of 25 nm is introduced.
Was formed.

Next, the film on which the pin type amorphous silicon layer was formed was set in a vacuum evaporation apparatus, and an indium tin oxide layer having a thickness of 100 nm was evaporated by an electron beam method to form a hetero electrode layer. Finally, a 100 nm palladium layer was vacuum-deposited thereon in a comb shape to form a film-shaped solar cell.

In these steps, there was no problem such as deformation of the film due to heat or wrinkles, and a solar cell having excellent flatness was obtained. When the photoelectric conversion efficiency of the obtained solar cell was measured, it was as good as 6.8%.

Example 2 Using the same polymer solution as in Example 1, a film was formed in the same manner as in Example 1. Tenter temperature is 280 ° C, stretching ratio is MD
The direction is 1.1 times, the TD direction is 1.4 times, and the temperature unevenness is 2 ° C.
Was 0.7% of the average temperature. The temperature unevenness during cooling was 7%. The properties of this film are shown in Table 1, but the amount of tarmi was small.

[0058] Also, MD, respectively 1100 kg / mm ² Young's modulus for the TD direction, 1500 kg / mm ^2, elongation of 55%, was 42%. The moisture absorption was 1.6%.

Using this, a solar cell was produced in the same manner as in Example 1, but a solar cell having excellent flatness was obtained without any problems such as deformation of the film due to heat or wrinkling in the process.

The photoelectric conversion efficiency was 6.7%.

Example 3 Using the same polymer solution as in Example 1, a film was formed in the same manner as in Example 1. Tenter temperature is 300 ° C, stretching ratio is MD
The direction is 1.1 times, the TD direction is 1.3 times, and the temperature unevenness is 5 ° C.
Was 1.7% of the average temperature. The temperature unevenness during cooling was 12%. Table 1 shows the characteristics of the film.

Using this, a solar cell was produced in the same manner as in Example 1, but both ends of the film were partially deformed by heat in the process, but there was no problem in the center. There were no problems such as wrinkles when wound up. The photoelectric conversion efficiency was 6.5%.

Comparative Example 1 A film was formed using the same polymer solution as in Example 1. The tenter temperature is 300 ° C., the stretching ratio is 1.1 times in the MD direction, T
Although the direction D was 1.3 times, the temperature unevenness was as large as 10 ° C., 3.3% of the average temperature. On the other hand, the temperature unevenness during cooling was 8%. Table 1 shows the characteristics of the obtained film.
As shown in the figure, the film was large in thickness.

A solar cell was manufactured in the same manner as in Example 1. However, in the process, the portion corresponding to the film tarmi discolored due to heat. There were many and it was not in a state that could be made into a solar cell.

Comparative Example 2 A film was formed using the same polymer solution as in Example 1. The tenter temperature is 300 ° C., the stretching ratio is 1.1 times in the MD direction, T
The direction D is 1.3 times and the temperature unevenness is 10 ° C. (3.10 of the average temperature).
3%). The temperature unevenness during cooling was 20%. The characteristics of this film are shown in Table 1, and the amount of tarmi was large.

Using this, a solar cell was produced in the same manner as in Example 1, but the discoloration and wrinkles were large.

Comparative Example 3 A film was formed using the same polymer solution as in Example 1. Tenter temperature is 245 ° C, stretching ratio is 1.1 times in MD direction, T
The direction D was 1.3 times and the temperature unevenness was 0.8% of the average temperature. The temperature unevenness during cooling was 12%. The characteristics of this film are shown in Table 1, and the film had a large heat shrinkage.

An attempt was made to manufacture a solar cell using this in the same manner as in Example 1. However, the film was deformed by heat during the process, and a solar cell could not be manufactured.

[0069]

[0070]

As described above, the aromatic polyamide film of the present invention comprises:
Thermal shrinkage in the TD direction at 210 ° C. is 2% or less, 610 m
The film is characterized in that the thickness of the film at the center when a load of 0.5 kg / mm ² is applied to a film having a width of 2 m and a length of 2 m is 60 mm or less, so that the flatness is good and the surface defects are small. . Therefore, a solar cell provided with an amorphous silicon thin film on a film becomes flat and has excellent film characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method of measuring the amount of tarmi.

FIG. 2 is a diagram illustrating a method for obtaining a tarmi amount.

[Explanation of symbols]

 1: Film 2: Thread 3: Roll

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00

Claims (2)

[Claims] 1. The film has a heat shrinkage of 210% or less in the width direction of 2% or less, and 0.5% for a film of 610 mm width and 2 m length.
An aromatic polyamide film, wherein the amount of tarmi of the film at the center when a load of kg / mm ² is applied is 60 mm or less. 2. A solar cell comprising the aromatic polyamide film according to claim 1 and an amorphous silicon thin film provided thereon.