JP3346228B2 - Aromatic polyimide film, laminate and solar cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to at least 15
A polyimide prepared by reacting a tetracarboxylic acid component containing mol% biphenyltetracarboxylic acids with an aromatic diamine component containing at least 5 mol% phenylenediamine, having a thickness of 10 to 250 μm,
The maximum roughness of the film surface is 50 nm or less, the coefficient of linear expansion is 5 to 20 × 10 ⁻⁶ cm / cm / ° C., the tensile modulus is 450 kg / mm ² or more, and the elongation is 15% or more. , Specific edge resistance is 11-22 kg / 20 mm /
The present invention relates to an aromatic polyimide film having a thickness of 10 μm and a residual volatile content of 0.5% by weight or less. Further, the present invention provides a laminate in which a conductive inorganic material layer is laminated on the surface of the substrate made of the aromatic polyimide film, and an amorphous silicon or polycrystalline silicon layer on the surface of the substrate made of the aromatic polyimide film. The present invention relates to a solar cell provided with electrodes.

[0002]

2. Description of the Related Art Conventionally, an amorphous silicon solar cell has a transparent electrode, amorphous silicon (a-
A solar cell is formed by sequentially forming a Si) layer and a metal electrode layer. The net thickness of the solar cell is about 2 μm. For the purpose of increasing the size and workability of the solar cell, a solar cell formed using a heat-resistant plastic film having a thickness of about several tens of μm as a substrate instead of a glass plate is being studied. This film-shaped solar cell is expected as a new applied product such as being incorporated into building materials. As the film for the substrate, high rigidity and heat resistance, low volatile matter content, small linear expansion coefficient, and workability such as punching are required, so that the biphenyltetracarboxylic acid component and the phenylenediamine component are used. And a polyimide film containing such a polyimide film. Such a polyimide film is described in, for example, Japanese Patent Publication No. Sho 60-42817.

However, this polyimide film is not satisfactory in terms of surface smoothness, dimensional stability, punching property and the like. For this reason, various improvements have been made to the polyimide film.
No. 7 discloses a method for producing a dimensionally stable polyimide film by re-heat treating a polyimide film obtained from biphenyltetracarboxylic dianhydride and paraphenylenediamine under low tension.
Japanese Patent Application Laid-Open Publication No. H11-157210 discloses a polyimide film excellent in dimensional stability having a linear expansion coefficient ratio (feed direction / perpendicular direction) and a linear expansion coefficient in a feed direction within a specific range.

However, according to these known techniques, although the thermal characteristics such as linear expansion and dimensional stability are improved, an aromatic polyimide film having good punching properties, particularly good punching properties and good surface smoothness are obtained. An aromatic polyimide film could not be obtained. Further, Japanese Unexamined Patent Publication No.
No. 334110 discloses that crack resistance is 50 to 70 kgf.
It is clear that the / 20 mm polyimide film has excellent punching properties. Further, it is stated that the polyimide film must have some% of a hygroscopic solvent remaining.

[0005] Considering the high requirements for heat resistance, electrical insulation and dimensional stability as well as mechanical strength, especially tensile modulus, etc. as a film for a solar cell substrate, an aromatic polyimide film is made of a tetracarboxylic acid component. And a phenylenediamine component as an aromatic diamine component. Further, since amorphous silicon or polycrystalline silicon and an electrode are provided on the surface of the aromatic polyimide film, the bonding force on the lamination surface with the conductive inorganic material layer must be large. This is a necessary property from the viewpoint of the durability of the laminate.

However, according to the study by the present inventors, the technique described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-334110 utilizes a bicarboxylic compound containing a biphenyltetracarboxylic acid component as a tetracarboxylic acid component and uses an aromatic diamine component as an aromatic diamine component. It has been found that it is not possible to impart satisfactory properties to an aromatic polyimide film produced using a material containing a phenylenediamine component.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-resistant, electrically insulating, dimensionally stable and mechanically applicable substrate film for a laminate such as a solar cell having a conductive inorganic material layer laminated thereon. An object of the present invention is to provide an aromatic polyimide film having good punching properties and good bonding properties as well as mechanical strength. It is another object of the present invention to provide a laminate and a solar cell using the substrate made of the aromatic polyimide film.

[0008]

SUMMARY OF THE INVENTION The present invention provides a tetracarboxylic acid component containing at least 15 mol% of biphenyltetracarboxylic acid or a dianhydride or an ester thereof, and an aromatic diamine component containing at least 5 mol% of phenylenediamine. Having a thickness of 10 to 250 μm, a maximum roughness of at least one film surface of 50 nm or less, and a linear expansion coefficient of 5 to 20 × 10 ⁻⁶ cm / cm / ° C, the tensile modulus is 450 kg / mm ² or more, the elongation is 15% or more, and the specific crack resistance is 11 to 22 kg / mm.
The present invention relates to an aromatic polyimide film having a thickness of 20 mm / 10 μm and a residual volatile matter content of 0.5% by weight or less. Further, the present invention provides a laminate in which a conductive inorganic material is laminated on the surface of the substrate made of the aromatic polyimide film, and amorphous silicon or polycrystalline on the surface of the substrate made of the aromatic polyimide film. The present invention relates to a solar cell provided with a silicon layer and an electrode.

[0009] In this specification, the end crack resistance (or specific end crack resistance) means the average value of the end tear resistance (or specific end crack resistance) of the sample (5 pieces) measured according to JIS C2318. Specifically, the center line of the V-shaped notch plate test bracket having the upper thickness of 1.00 ± 0.05 mm of the constant-speed tension-type tensile tester was made to coincide with the center line of the upper grip, and the top of the cut and the lower grip were Attach the handle so that the interval is about 30 mm. A test piece with a width of about 20 mm and a length of about 200 mm is passed through the hole of the bracket, folded into two parts, clamped at the lower part of the tester, pulled at a speed of about 200 mm per minute, and pulled apart. Is called end tear resistance.
Five test pieces were taken from the longitudinal direction and the lateral direction over the entire width, respectively, and the average value of the end crack resistance was determined and shown as the end crack resistance value. The specific edge tear resistance indicates an edge tear resistance per film thickness (10 μm conversion). The maximum roughness of the surface of the aromatic polyimide film in the present invention is determined by using a stylus-type roughness meter (for example, Taristep, manufactured by Rank-Tape of Hobson) with a cutoff of 0.33 Hz and a vertical magnification of 200,000 times. , 2,000 times horizontal magnification, 50 μm measurement length, JIS
It means a value measured by a method according to -B-0601, and the smaller the value, the better the surface smoothness.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention are listed below. 1) Specific crack resistance is 11 to 15 kg / 20 mm / 10 μ
m. The above aromatic polyimide film in the range of m. 2) The aromatic polyimide film having a residual volatile matter content of 0.35% by weight or less. 3) The above-mentioned aromatic polyimide film, wherein at least one layer containing a smooth surface of the film contains an inorganic filler. 4) The aromatic polyimide film whose surface has been subjected to at least one of a surface treatment agent or a surface activator treatment, a corona discharge treatment, a flame treatment, an ultraviolet treatment, and a low-temperature or normal-pressure plasma treatment. .

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an example of the laminate of the present invention. FIG. 2 is a partial cross-sectional view of an example of the solar cell of the present invention. FIG. 3 is a schematic perspective view of an example of the film solar cell of the present invention.

In FIG. 1, a laminate 1 is formed by laminating a conductive inorganic material layer 3 on a smooth surface of a substrate 2 made of an aromatic polyimide film. In FIG. 2, the solar cell 10
Is formed on an amorphous silicon layer composed of an n-layer, an i-layer and a p-layer or a polycrystalline silicon layer 4 (not shown) and a metal electrode 5a and a transparent electrode 5b (shown in FIG. However, the transparent electrode 5b may be a combination of a transparent conductive film and an electrode.).

The biphenyltetracarboxylic acid component in the present invention includes 2,3,3 ', 4'-biphenyltetracarboxylic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, dianhydrides thereof, Alternatively, esters thereof can be used, and among them, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is preferably used.

The aromatic tetracarboxylic acid component which can be used in combination with the biphenyltetracarboxylic acid component in the present invention includes pyromellitic dianhydride, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride, 2,
2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl)
Propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ) Ether dianhydride, 2,3,6
7-naphthalenetetracarboxylic dianhydride, 1,4
5,8-naphthalenetetracarboxylic dianhydride, 1,
2,5,6-naphthalenetetracarboxylic dianhydride,
2,2-bis (3,4-dicarboxyphenyl) -1,
1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl)-
Examples thereof include 1,1,1,3,3,3-hexafluoropropane dianhydride.

The phenylenediamine in the present invention is
Although any of p-phenylenediamine, m-phenylenediamine and o-phenylenediamine may be used, p-phenylenediamine is particularly preferably used. Aromatic diamine components that can be used in combination with phenylenediamine include diaminodiphenyl ether, 4,4′-
Diaminodiphenylpropane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenylmethane,
4,4'-diaminodiphenyl sulfide, bis [4-
(4-aminophenoxy) phenyl] methane, 2,2-
Bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-bis [4- (aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] ether and the like.

In the present invention, the aromatic polyimide film (or surface-treated film) is composed of the above-mentioned monomer component and has a thickness of 10 to 250 μm, particularly 2 μm.
It is preferably from 0 to 125 μm, particularly preferably from 25 to 80 μm. When the thickness of the aromatic polyimide film is smaller than the lower limit, the self-supporting property is low. The linear expansion coefficient (50 to 20)
(0 ° C.) is within the above range, the dimensional stability under various environments (high temperature, etching, etc.) is good.
Further, when the tensile modulus and the elongation are within the above ranges, the handling as the substrate film is good. On the other hand, if the amount of the remaining volatiles is more than 0.5% by weight, problems occur in the bonding property and the dimensional stability. If the maximum roughness and specific tear resistance of the film surface of the aromatic polyimide film are outside the above ranges, the object of the present invention cannot be achieved.

The aromatic polyimide film of the present invention comprises:
For example, it can be manufactured as follows. Preferably, first, a polyimide such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone is prepared from the above tetracarboxylic dianhydride, preferably biphenyltetracarboxylic acid and phenylenediamine, preferably paraphenylenediamine. The polymer is polymerized in an organic polar solvent generally used at a temperature of preferably 10 to 80 ° C. for 1 to 30 hours, and the logarithmic viscosity of the polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 100 ml)
Solvent, solvent: N, N-dimethylacetamide)
-5, a polyamic acid (imidation ratio: 5% or less) solution having a polymer concentration of 15 to 25% by weight and a rotational viscosity (30 ° C.) of 500 to 4500 poise.

Next, preferably, the polyamic acid 10
0.01 to 1% by weight, based on 0 parts by weight, of a phosphorus compound, for example, an organic phosphorus compound or an inorganic phosphorus compound such as a (poly) phosphate ester and / or an amine salt of a phosphate ester, and preferably further a polyamic acid Acid 100
0.02 to 6 parts by weight of an inorganic filler such as colloidal silica, silicon nitride, talc, titanium oxide, or calcium phosphate (preferably having an average particle diameter of 0.005 to 0.5 parts by weight).
5 μm, especially 0.005 to 0.2 μm) to prepare a polyamic acid solution composition. These inorganic fillers may be present uniformly throughout the film layer, or
When a film having a three-layer structure is formed, it is preferable that the film is contained in the above-mentioned ratio in a layer containing at least one surface, thereby providing surface smoothness while forming fine projections on at least one surface. (Alternatively, when the glass transition temperature of the obtained polyimide is 430 ° C. or lower, it is also achieved by heating at a temperature higher than the glass transition temperature of the obtained polyimide, preferably 30 ° C. or higher to complete the imidization. .)

This polyamic acid solution composition is cast on a glass or metal support having a smooth surface to form a thin film of the solution, and when the thin film is dried,
Adjust the drying conditions (preferable temperature: 100 to 16
(0 ° C., time: 1 to 60 minutes) By drying, the solidified film has a volatile content of 30 to 50% by weight and an imidization rate of 10 to 60% in the solidified film. A solidified film is formed, and the solidified film is peeled from the support surface.

Next, after one or both surfaces of the solidified film are coated with a surface treating solution containing an aminosilane-based, epoxysilane-based or titanate-based surface treating agent, the film can be further dried. As the surface treatment agent, γ-
Aminopropyl-triethoxysilane, N-β- (aminoethyl) -γ-aminopropyl-triethoxysilane, N- (aminocarbonyl) -γ-aminopropyl-
Triethoxysilane, N- [β- (phenylamino)-
Ethyl] -γ-aminopropyl-triethoxysilane,
Aminosilanes such as N-phenyl-γ-aminopropyl-triethoxysilane, γ-phenylaminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) -ethyl-trimethoxysilane, γ-glycidyloxypropyl Heat-resistant surface treatment agents such as epoxysilanes such as -trimethoxysilane and titanates such as isopropyl-tricumylphenyl-titanate and dicumylphenyl-oxyacetate-titanate; The surface treatment solution is prepared by adding the above surface treatment agent to 0.5 to 50.
It can be used as a solution of an organic polar solvent such as a lower alcohol or an amide-based solvent containing 1 wt%. The surface treatment liquid is preferably applied uniformly using a gravure coating method, a silk screen, a dipping method or the like to form a thin layer. Further, a surface activator, for example, an amorphous polyimide may be applied to the above-mentioned polyamic acid solution film and treated with the surface activator.

FIG. 4 shows an example of a method for producing an aromatic polyimide film according to the present invention, which shows preferable heating conditions before curing in a curing furnace. That is, the solidified film obtained as described above is further dried if necessary, and preferably after the volatile film content of the dried film is adjusted to 10 to 45% by weight,
In the state where both edges in the width direction of the dried film are gripped,
Temperature (° C.) (preferably 100 to 250 ° C.) at the entrance of the curing furnace in the curing furnace shown in 4 × Residence time (minutes)
After drying so that is within the range of the oblique line, the maximum heating temperature: 4
The dried film is heated and dried and imidized at a temperature of 00 to 500 ° C. for 0.5 to 30 minutes to obtain a imide having a residual volatile content of 0.5% by weight or less, particularly 0.35% by weight or less. By completing the conversion, an aromatic polyimide film can be suitably produced. After the curing step, one or both surfaces of the aromatic polyimide film are alkali-treated (for example, after immersion in an aqueous alkali solution such as potassium hydroxide or hydrazine hydrate, washed with water and dried), and then the surface treatment liquid is applied. The film surface can be similarly surface-treated by drying and drying.

The aromatic polyimide film obtained as described above is preferably used under low tension or no tension.
Heat at a temperature of about 00 to 400 ° C. to perform stress relaxation treatment,
Take up.

In the above-mentioned aromatic polyimide film, the heating conditions before the curing in the curing furnace during the above-mentioned production are controlled within the range shown in FIG. 4 and the curing conditions are adjusted to the above-mentioned temperature and time. When the thickness is within the range, the thickness is 10 to 250 μm, particularly 20 to 80 μm, the amount of residual volatile matter is 0.5% by weight or less, particularly 0.35% by weight or less, and the specific crack resistance is within this range. The value specified in the invention can be taken.

The aromatic polyimide film of the present invention comprises:
Preferably, the tetracarboxylic dianhydride is 3,3 ′,
It can be easily obtained by a method of polymerizing 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine as an aromatic diamine, but as a polyamic acid, it is within a range satisfying the physical properties of the film. If so, other components may be polymerized together with 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine, and the type of bond may be random polymerization or block polymerization. You may. If the total amount of each component in the finally obtained polyimide film is within the above range, polyamic acid containing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine And a polyamic acid component composed of other components may be mixed and used. In either case, the polymer is cut and recombined at the time of heating at a high temperature, and the target aromatic polyimide film can be obtained in the same manner as described above. Further, the aromatic polyimide film in the present invention is not limited to the above-mentioned thermal imidization, and can be similarly performed by chemical imidization as long as the conditions are within the above range. In order to improve the coefficient of linear expansion and the elastic modulus, the self-supporting film may be stretched in one direction or two directions.

The aromatic polyimide film of the present invention is preferably subjected to corona discharge treatment as it is or when not treated with a surface treating agent or a surface activator.
Surface treatment is performed by low-temperature or normal-pressure plasma treatment, ultraviolet irradiation, and flame treatment.

The laminate of the present invention has at least 15 mol
% Biphenyltetracarboxylic acid or its dianhydride
Or a tetracarboxylic acid component containing an ester,
Aromatic diamine containing 5 mol% of phenylenediamine
From polyimide produced by reaction with
At least one of which has a thickness of 10 to 250 μm
Has a maximum roughness of 50 nm or less on the film surface,
Tension coefficient is 5-20 × 10 ^-6cm / cm / ° C, tensile
Elastic modulus is 450kg / mm^TwoMore than, 15% growth
The specific crack resistance is 11 to 22 kg / 20 mm.
/ 10 μm and the residual volatile matter amount is 0.5% by weight or less.
Smooth table of a substrate made of an aromatic polyimide film
On the surface, a method known per se, for example, CVD (chemical
The deposition is performed by a vapor deposition method or a sputtering method.
It is obtained by laminating an electrically conductive inorganic material layer. Said
Examples of the conductive inorganic material include Al, Au, Ag, and Cu.
Which metal thin film or In_TwoO_Three, SnO_Two, ZnO, Cd
_TwoSnO_Four, In_TwoO_ThreeSuch as ITO with Sn added to
An oxide semiconductor and the like can be given. The conductive inorganic material described above
The layer usually has a thickness of about 30 to 1000 nm.

[0027] The solar cell of the present invention is a reaction between a tetracarboxylic acid component containing at least 15 mol% of biphenyltetracarboxylic acid or a dianhydride or an ester thereof and an aromatic diamine component containing at least 5 mol% of phenylenediamine. A thickness of 10 to 250 μm, a maximum roughness of at least one film surface is 50 nm or less, and a coefficient of linear expansion is 5 to 20 × 10 ⁻⁶ cm / cm / ° C. , Tensile modulus is 450 kg / mm ² or more and elongation is 15%
The specific crack resistance is 11 to 22 kg / 20 mm.
/ 10 μm and an amorphous silicon or polycrystalline silicon layer on a smooth surface of a substrate made of an aromatic polyimide film having a residual volatile matter content of 0.5% by weight or less by a method known per se, for example, the following method And electrodes. For example, the aromatic polyimide film is placed in a low-vacuum reaction chamber, and a metal electrode layer is formed on the smooth surface by CVD using aluminum. Next, the substrate temperature is set to 200 to 35.
0 ° C., high-frequency plasma discharge was performed in a gas obtained by adding phosphine (PH ₃ ) to SiH ₄ , and a
-Si (n-layer) is formed, followed by formation of an a-Si (i-layer) of about 500 nm using only SiH ₄ gas, followed by SiH
₄ to which diborane (B ₂ H ₆ )
-Form Si (p layer). Further, a transparent electrode layer of indium, tin, oxide and tin oxide is formed thereon by the CVD method, and the transparent electrode / p-type a-Si / i-type a-Si / n-type a-
A solar cell having a structure of Si / metal electrode / film is obtained. Further, a structure may be employed in which the p-layer is a-Si and the n-layer is crystalline Si, and a thin undoped a-Si layer is inserted between the layers.
In particular, when a hybrid type of a-Si / polycrystalline silicon is used, the sensitivity to the sunlight spectrum is improved.

[0028]

Embodiments of the present invention will be described below. In each of the following examples, parts mean parts by weight. In each of the following examples,
Physical properties of the aromatic polyimide film were measured by the following methods. Tensile modulus: measured according to ASTM D882-64T (MD) Elongation: measured according to ASTM D882-64T (M
D) Coefficient of linear expansion (50-200 ° C.): A sample subjected to stress relaxation by heating at 300 ° C. for 30 minutes was subjected to a TMA device (tensile
(2g load, sample length 10mm, 20 ° C / min)

The imidization ratio: calculated from the ratio of absorbance at 1780 cm ^-1 and 1510 cm ^-1 by FI-IR (ATR method). The measurement was performed on the A side of the film. Residual volatile amount (solidified film): determined by the following equation. Residual volatile matter amount (solidified film) = [(AB) / A] x 1
00 A: Film weight before heating B: Film weight after heating at 420 ° C. for 20 minutes Remaining volatile matter (polyimide film): Determined by the following formula. Amount of residual volatile matter (polyimide film) = [(AB) /
A] × 100 A: Weight after drying at 150 ° C. × 10 minutes B: Weight after drying at 450 ° C. × 20 minutes (Measurement is usually performed in air, but may be performed in nitrogen.) Measured according to ASTM D570-63 (23
℃ × 24 hours)

Dielectric breakdown voltage: ASTM D149-64
(25 ° C.) Volume resistivity: measured according to ASTM D257-61 (25 ° C.) Dielectric constant: measured according to ASTM D150-64T (2
5 ℃, 1KHz)

Reference Example 1 3,470 parts of N, N-dimethylacetamide
294.33 parts of 3 ', 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine 108.14
And polymerized at 30 ° C. for 10 hours to obtain a polyamic acid solution. Logarithmic viscosity of this polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 100 ml solvent, solvent:
(N, N-dimethylacetamide) was 2.66, and the rotational viscosity of the solution at 30 ° C. was 3,100 poise.

Reference Example 2 4,4 ′ was added to 2570 parts of N, N-dimethylacetamide.
After adding 200.24 parts of -diaminodiphenyl ether, 218.12 parts of pyromellitic dianhydride were added,
A polymerization reaction was performed at 20 ° C. for 6 hours to obtain a polyamic acid solution. The logarithmic viscosity of this polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 100 ml solvent, solvent: N, N-dimethylacetamide) is 1.60, and the rotational viscosity at 30 ° C. of the solution is 300 poise. there were.

Reference Example 3 N-methyl-2-pyrrolidone in 1980 parts, 3,3 ',
4,4'-biphenyltetracarboxylic dianhydride 14
7.2 parts, pyromellitic dianhydride 100.1 parts, p-
75.7 parts of phenylenediamine and 60.6 parts of 4,4′-diaminodiphenyl ether were added, and a polymerization reaction was carried out at 20 ° C. for 6 hours to obtain a polyamic acid solution. This polymer
Logarithmic viscosity (measuring temperature: 30 ° C., concentration: 0.5 g / 10
0 ml solvent, solvent: N-methyl-2-pyrrolidone) is 2.51, and the rotational viscosity at 30 ° C. of the solution is 2900.
Poise.

Example 1 To the polyamic acid solution obtained in Reference Example 1, 0.1 part of monostearyl phosphate triethanolamine salt and 0.5 part of (100 parts of polyamic acid) were added. Colloidal silica having an average particle size of 0.08 μm (based on solid content) was added and uniformly mixed to obtain a polyamic acid solution composition. The rotational viscosity of this polyamic acid solution composition was 3000 poise. This polyamic acid solution composition is continuously extruded from a slit of a T-die mold onto a smooth support of a casting / drying furnace to form a thin film of the solution, and dried at an average temperature of 141 ° C. to obtain a long film. To form a solidified film. By peeling from the surface of the support, a long solidified film was obtained. Next, an aminosilane surface treatment solution of N, N-dimethylacetamide was uniformly applied to both surfaces of the long solidified film, and then dried to obtain a dried film having a surface treated. This dried film had a residual volatile matter amount of 28% by weight consisting of the solvent and the produced water. Next, while holding the dried film in the width direction, the dried film is cured in a curing furnace (temperature at the inlet × residence time = 24).
0 ° C × 2 minutes, maximum temperature × maximum temperature residence time = 480 ° C ×
1 minute), a long aromatic polyimide film having a thickness of 25 μm, both surfaces of which were treated with a surface treating agent, was continuously produced.
Table 1 shows the results of measurement and evaluation of this aromatic polyimide film.

The above-mentioned aromatic polyimide film is
Then, a metal conductive layer is formed on the surface by CVD using aluminum. Next, the substrate temperature was set to 250 ° C.
To to perform a phosphine (PH ₃₎ high-frequency plasma discharge in the added gas and (13.56 MHz) to SiH _4, to form an a-Si of about 20 nm, followed by about 500nm only SiH ₄ gas a- Forming Si, followed by Si
Diborane (B ₂ H ₆ ) is added to H ₄ gas to about 10 n
m-p-Si is formed. In addition, indium
Form a transparent electrode layer of tin oxide, tin oxide by CVD method,
A solar cell was manufactured.

Example 2 Acetic anhydride 6 was added to 2872 parts of the polyamic acid solution of Reference Example 1.
A dry film was obtained in the same manner as in Example 1 except that 0 part and 33 parts of isoquinoline were mixed and no surface treatment was performed. This dried film had a residual volatile matter amount of 26% by weight. Next, while holding the dried film in the width direction, it is cured in a curing furnace (temperature at inlet × residence time = 2).
00 ° C × 4 minutes, maximum temperature × maximum temperature residence time = 480 ° C
× 3 minutes), and a long aromatic polyimide film having a thickness of 50 μm was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Next, a solar cell was manufactured in the same manner as in Example 1.

Example 3 A dried film surface-treated in the same manner as in Example 1 except that the slit width of the T-die was changed. This dried film had a residual volatile matter amount of 28% by weight. Next, while holding the dried film in the width direction, the dried film is cured in a curing furnace (temperature at inlet × residence time = 200 ° C. × 2.
5 minutes, maximum temperature x maximum temperature residence time = 480 ° C x 3
Minutes), a long aromatic polyimide film having a thickness of 50 μm, both surfaces of which were treated with a surface treating agent, was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Next, a solar cell was manufactured in the same manner as in Example 1.

Example 4 An elongated solidified film was obtained in the same manner as in Example 2 except that the slit width of the T-die was changed. Next, a dried film surface-treated in the same manner as in Example 1 was obtained. This dried film had a residual volatile matter content of 30% by weight. Then
While holding the dried film in the width direction, it is cured in a curing furnace (temperature at the inlet × residence time = 140 ° C.)
× 5 minutes, maximum temperature × maximum temperature residence time = 480 ° C × 3
Min), a long aromatic polyimide film having a thickness of 75 μm was continuously produced. Both surfaces of this aromatic polyimide film were alkali-treated (immersed in a solution composed of potassium hydroxide / hydrazine hydrate / water for 3 minutes, washed with acid, washed with water and dried), and then subjected to surface treatment in the same manner as in Example 1. A long aromatic polyimide film having a thickness of 75 μm and having both surfaces treated with a surface treatment agent was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Further, a solar cell was produced in the same manner as in Example 1.

Example 5 An elongated solidified film was obtained in the same manner as in Example 1 except that the slit width of the T-die was changed. The dried film was obtained by heating and drying in the same manner as in Example 1 without applying the surface treatment liquid to both surfaces of the long solidified film. This dried film had a residual volatile matter content of 30% by weight. Then, while holding the dried film in the width direction, the film is cured in a curing furnace (temperature at the inlet × residence time = 105 ° C. × 9 minutes, maximum temperature × maximum temperature residence time = 450 ° C. × 15 minutes), A long aromatic polyimide film having a thickness of 75 μm was continuously manufactured. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Further, a solar cell was produced in the same manner as in Example 1.

Example 6 A long aromatic polyimide film having a thickness of 50 μm was continuously produced in the same manner as in Example 1 except that the polyamic acid solution of Reference Example 3 was used. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film.
Further, a solar cell was produced in the same manner as in Example 1.

Comparative Example 1 A long aromatic polyimide film having a thickness of 50 μm was continuously produced in the same manner as in Example 1 except that the polyamic acid solution of Reference Example 2 was used. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film.
Further, a solar cell was produced in the same manner as in Example 1.

Example 7 When the cut surfaces of the aromatic polyimide films obtained in Examples 1 to 6 were cut with a mold, linearity was maintained in all cases. The heat shrinkage of the aromatic polyimide film obtained in Examples 1 to 6 (250 ° C., 2 hours:
JIS C2318) was 0.3% or less in all cases.

Example 8 When the solar cells obtained in Examples 1 to 6 were used outdoors for one year, no deterioration in characteristics was observed.

[0044]

[Table 1]

[0045]

Since the present invention is configured as described above, the following effects can be obtained. The aromatic polyimide film of the present invention has good bonding properties and punching properties. Further, the laminate of the present invention exhibits excellent moldability and bonding properties. further,
The solar cell of the present invention exhibits excellent durability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a laminate of the present invention.

FIG. 2 is a partial cross-sectional view of an example of the solar cell of the present invention.

FIG. 3 is a schematic perspective view of an example of the film solar cell of the present invention.

FIG. 4 shows a range of suitable heating conditions before curing in a curing furnace in an example of a method for producing an aromatic polyimide film according to the present invention. Vertical axis Temperature at the entrance of cure furnace (° C) x residence time (min) Horizontal axis Film thickness (μm) Oblique line Preferred range 1 Laminate 2 Substrate made of aromatic polyimide film 3 Conductive inorganic material layer 4 Amorphous silicon or polycrystal Silicon layer 4n n layer 4ii layer 4pp layer 5 electrode 5a metal electrode 5b transparent electrode 10 solar cell

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-215631 (JP, A) JP-A-8-100072 (JP, A) JP-A-8-134232 (JP, A) JP-A-9-99 JP-A-8-47978 (JP, A) JP-A-9-8338 (JP, A) JP-A-8-264818 (JP, A) JP-A-10-310639 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/18

Claims (5)

(57) [Claims] 1. A polyimide prepared by reacting a tetracarboxylic acid component containing at least 15 mol% of biphenyltetracarboxylic acid or a dianhydride or ester thereof with an aromatic diamine component containing at least 5 mol% of phenylenediamine. Consisting of 10-25 thickness
0 μm, the maximum roughness of at least one film surface is 50 nm or less, and the linear expansion coefficient is 5 to 20 × 1.
0 ^-6 cm / cm / ° C and a tensile modulus of 450 kg / cm
and mm ² or more, elongation is 15% or more, the ratio end cleft resistance 11~22kg / 20mm / 10μm and an aromatic polyimide film residual volatile amount is 0.5 wt% or less. 2. The aromatic polyimide film according to claim 1, wherein at least one of the layers having a smooth surface contains an inorganic filler. 3. The surface is subjected to one or more of a surface treatment agent or a surface activator treatment, a corona discharge treatment, a flame treatment, an ultraviolet treatment, a polar solvent treatment, a low temperature or normal pressure plasma treatment. The aromatic polyimide film according to claim 1. 4. A laminate comprising a conductive inorganic material layer laminated on the surface of the substrate made of the aromatic polyimide film according to claim 1. 5. A solar cell comprising the substrate made of the aromatic polyimide film according to claim 1 and an amorphous silicon or polycrystalline silicon layer and electrodes provided on the surface.