JP2000085086A - Manufacture of laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminated film without defects of wrinkles and inclusion of an air by laminating a thermoplastic resin film in a state wherein a base film is stretched by applying a tension in biaxial directions. SOLUTION: A base film 12 is guided by a guide roll 11, increased a width by a banana roll 13, and stretched in a lengthwise direction for stretching biaxial directions. In this state, a thermoplastic resin film 15 guided by a guide roll 14 is laminated on the base film 12, and pressed by press rolls 16 and 17 for integrally laminating, and a laminated film 18 is obtained. At the time of integral laminating, a tension loaded to the base film 12 is appropriately determined by component resins, film thickness or the like of the base film 12 and the thermoplastic resin film 15. For example, in the case of manufacturing an EVA/PET/EVA laminated film for a sealing film of a solar battery, preferably the EVA resin contains an vinyl acetate of 30 wt.% or lower and has a melt flow rate of 0.7-20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated film, and more particularly, to a wrinkle suitable as an EVA (ethylene-vinyl acetate copolymer) / PET (polyethylene terephthalate) laminated film for a sealing film of a solar cell. The present invention relates to a method for producing a laminated film having no problem of mixing air or air (bubbles).

[0002]

2. Description of the Related Art In recent years, solar cells which directly convert sunlight into electric energy have been attracting attention from the viewpoints of effective use of resources and prevention of environmental pollution, and their development has been promoted. As shown in FIG. 2, a solar cell generally has a configuration in which a silicon power generation element 4 is sealed between a glass substrate 1 and a back cover 2 by sealing films 3A and 3B.

Conventionally, an EVA film made of an EVA resin composition containing a cross-linking agent has been used as a sealing film 3A, 3B of a solar cell in terms of cost and durability.

In such a solar cell, a glass substrate 1, a sealing film 3A, a silicon power generating element 4, a sealing film 3B and a back cover 2 are laminated in this order, and heated and pressed to form a sealing film 3
It is manufactured by cross-linking and curing EVA of A and 3B and bonding and integrating.

Incidentally, the sealing films 3A and 3B are required to have sufficiently high volume resistivity in view of the performance. Then, in order to improve the volume resistivity, the two EVA
There is also provided a sealing film in which another film is sandwiched between films to form a three-layer laminated film. In this case, as the film of the intermediate layer, a polyester film, a polyethylene film, a polypropylene film, a polycarbonate film, a fluorinated polyethylene film, and the like are used.
Of these, particularly excellent insulation and low cost make P
Polyester films such as ET films are preferred.

[0006]

SUMMARY OF THE INVENTION However, EVA
When a three-layer laminated film such as / PET / EVA is laminated and integrated with a normal laminator, the resulting laminated film is liable to generate wrinkles, and there is also a problem of air entrapment between the films, resulting in high quality. A laminated film could not be manufactured.

[0007] Such a problem is not limited to a three-layer laminated film, but can also occur in a two-layer laminated film when different types of films are laminated and integrated. In particular, one of the laminated films contains a crosslinking agent. Including, after lamination integrated
In the case of performing thermal crosslinking, there is a problem that defects such as wrinkles increase due to shrinkage of one film during thermal crosslinking.

Therefore, when such a laminated film is used as a sealing film for a solar cell, a silicon power generation element is interposed between the glass substrate and the back cover via the sealing film in manufacturing the solar cell. When laminating and heating and pressurizing, the silicon power generation element is damaged due to wrinkling of the sealing film, and a high-quality solar cell cannot be manufactured with high yield.

The present invention solves the above-mentioned conventional problems and provides a method for producing a laminated film suitable for producing an EVA / PET / EVA laminated film for a sealing film of a solar cell, which is free from wrinkles and air entrapment. The purpose is to provide.

[0010]

The method for producing a laminated film according to the present invention is a method for producing a laminated film by laminating and integrating a thermoplastic resin film and a base film.
The thermoplastic resin film is laminated in a state where the base film is tensioned by applying tension in the biaxial direction.

According to the present invention, in producing a laminated film by laminating and integrating a thermoplastic resin film and a substrate film, the thermoplastic resin film is stretched in a state where tension is applied to the substrate film in biaxial directions. By laminating, wrinkles and air entrapment can be prevented and a high-quality laminated film can be manufactured.

In the present invention, in particular, when the base film is made of a resin having a melting point higher than that of the thermoplastic resin, or when another thermoplastic resin film is laminated and integrated on the non-laminated surface side, a two-layer film is formed. In the case where
Especially effective.

In the present invention, examples of the thermoplastic resin film include an EVA resin film containing a cross-linking agent.
It is suitable for producing a laminated film such as VA / PET / EVA.

[0014]

Embodiments of the present invention will be described below in detail.

In the present invention, in order to laminate and integrate the base film with the thermoplastic resin film in a state where the base film is stretched by applying tension in the biaxial directions, the base film is stretched in the width direction using various widening devices. In this case, the film may be laminated and integrated with the thermoplastic resin film while being stretched in the longitudinal direction.

Examples of such a widening device include various types of widening rollers such as a concave roller, an expander roller (banana roller), a spreader bar, a two-bend roller, a spiral roller, a slat expander roller, an ear nip roller, a tenter, and a free sprayer. Can be used.

FIGS. 1A and 1B show a case where a banana roller is used. FIG. 1A is a schematic plan view, and FIG. 1B is a side view. However, in FIG. 1A, the upper thermoplastic resin film and the guide roll of the thermoplastic resin film are not shown.

The base film 12 guided by the guide rolls 11 is widened by the banana rolls 13 and stretched in the longitudinal direction, thereby being tensioned in the biaxial directions. In this state, the thermoplastic resin film 15 guided by the guide rolls 14 is laminated on the base film 12 and pressed by the press rolls 16 and 17 to be laminated and integrated to obtain the laminated film 18.

In the lamination and integration, the base film 11
Is appropriately determined depending on the constituent resins of the base film 11 and the thermoplastic resin film 15 and the thicknesses thereof.

Hereinafter, EVA / PE for a sealing film of a solar cell will be described.
More detailed lamination conditions will be described by exemplifying a case of manufacturing a T / EVA laminated film.

First, the EVA resin composition constituting the EVA film used for producing such a laminated film will be described.

The EVA resin according to the present invention preferably has a vinyl acetate content of 30% by weight or less. If the vinyl acetate content exceeds 30% by weight, the water vapor transmission rate is too large, and it is difficult to obtain sufficient moisture proofness as a sealing film for a solar cell. However, an EVA resin having an excessively low vinyl acetate content has poor processability and an excessively high viscosity, so that the ability to follow a silicon power generation element during the production of a solar cell is poor. Therefore, the vinyl acetate content of the EVA resin is low. It is preferably at least 10% by weight.

The EVA resin used in the present invention is:
Melt flow rate is 0.7-20, especially 1.5-10
It is preferred that

The EVA resin composition used in the present invention has a cross-linking structure by adding a cross-linking agent for improving durability. The cross-linking agent generally generates a radical at 100 ° C. or higher. Organic peroxides are used, and those having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours are particularly preferable in consideration of the stability during compounding. Such organic peroxides include, for example, 2,5-dimethylhexane;
2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; 3-
Di-t-butyl peroxide; t-dicumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne; dicumyl peroxide;
α'-bis (t-butylperoxyisopropyl) benzene; n-butyl-4,4-bis (t-butylperoxy) butane; 2,2-bis (t-butylperoxy) butane; 1,1- Bis (t-butylperoxy) cyclohexane; 1,1-bis (t-butylperoxy) 3,
3,5-trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide and the like can be used. The compounding amount of these organic peroxides is generally 5 parts by weight or less, preferably 1 to 3 parts by weight, based on 100 parts by weight of the EVA resin.

Further, as a sealing film of a solar cell, a silane coupling agent can be added to the EVA resin for the purpose of improving the adhesion to the power generating element. Known silane coupling agents for this purpose, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris-
(Β-methoxyethoxy) silane; γ-methacryloxypropyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercapto Propyltrimethoxysilane; γ-aminopropyltrimethoxysilane; N-β
-(Aminoethyl) -γ-aminopropyltrimethoxysilane and the like. The amount of the silane coupling agent is generally 5 parts by weight or less, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the EVA resin.

Further, the gel fraction of the EVA resin is improved,
A crosslinking aid can be added to the EVA resin to improve durability. Examples of the crosslinking auxiliary used for this purpose include known triaryl isocyanurate; trifunctional crosslinking auxiliary such as triallyl isocyanate;
Monofunctional crosslinking assistants such as K ester can also be mentioned. The amount of these crosslinking aids is generally equal to the amount of EVA resin 1
10 parts by weight or less, preferably 1 to 5 parts by weight with respect to 00 parts by weight
Parts by weight.

Further, for the purpose of improving the stability of the EVA resin, hydroquinone, hydroquinone monomethyl ether, p-benzoquinone, methylhydroquinone and the like can be added, and the amount of these compounds is generally 100 parts by weight of the EVA resin. 5 parts by weight or less.

Further, if necessary, a coloring agent, an ultraviolet absorber, an antioxidant, an anti-tarnishing agent and the like can be added in addition to the above. Examples of the coloring agent include inorganic pigments such as metal oxides and metal powders, and organic pigments such as azo-based, phthalocyanine-based, azo-based, acidic or basic dye-based lakes. UV absorbers include 2-hydroxy-4-octoxybenzophenone; benzophenones such as 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2'-hydroxy-5-methylphenyl) benzotriazole; Benzotriazoles; phenyl salicylate; pt-
There are hindered amines such as butylphenyl salicylate. As anti-aging agents, amines; phenols;
Bisphenyl type; hindered amine type, for example, di-t-butyl-p-cresol; bis (2,2,6,6
-Tetramethyl-4-piperazyl) sebacate.

An EV comprising such an EVA resin composition
The thickness of the A film is generally about 10.0 to 800 μm.

On the other hand, a PET film having a thickness of about 30 to 100 μm is generally used.

In manufacturing an EVA / PET / EVA laminated film, first, a PET film is provided with 0-
2.0kgf tension, 4.0-7.0kgf in length direction
With the EVA film tensioned with 60% tension,
Laminate at ７５75 ° C., 1.0-2.5 kg / cm ² and laminate and integrate.

Next, a tension of 0 to 2.0 kgf in the width direction and a tension of 4.0 to 7.0 kgf in the length direction are applied to the obtained PET / EVA two-layer laminated film, and the film is tensioned. EVA film on PET film side at 60-75 ° C,
Laminate at 1.0 to 2.5 kg / cm ² and laminate and integrate.

By doing so, a good EVA / PET / EVA three-layer laminated film free of wrinkles and air mixing can be obtained.

The obtained laminated film has no problem of wrinkling of the laminated film due to shrinkage of the EVA film even when subjected to heat crosslinking at 100 to 150 ° C. in manufacturing a solar cell. Can be manufactured with good yield.

In the present invention, examples of the base film include a polyester film, a polyethylene film, a polypropylene film, a polycarbonate film, a fluorinated polyethylene, etc., which are interposed between the EVA films as the sealing film for the solar cell. Can be

[0036]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 A 25 μm-thick EVA resin composition having the following composition:
When laminating a VA film and a PET film having a thickness of 100 μm, as shown in FIG. 1, a 2.0 kgf tension in the width direction and a 7.0 kgf tension in the length direction were applied to the PET film using a banana roll. The EVA film was laminated in a tensioned state (temperature 70 ° C.,
Pressure 2.0 kg / cm ² ).

[EVA resin composition (parts by weight)] EVA resin (vinyl acetate content: 28% by weight, melt flow rate: 18): 100 Crosslinking agent: 1.5 Silane coupling agent: 1.0 Stabilizer: 0 5.5 The appearance of the obtained two-layer laminated film was observed, and the presence or absence of wrinkles or air was checked. As a result, it was confirmed that there was no wrinkles or air.

Example 2 An EVA film similar to that used in Example 1 was further laminated on the PET film side of the two-layer laminated film obtained in Example 1 to produce a three-layer laminated film. That is,
As shown in FIG. 1, using a banana roll, a tension of 2.0 kgf in the width direction and 7.0 k in the length direction were applied to the two-layer laminated film.
The EVA film was laminated while being tensioned by applying a tension of gf (temperature 70 ° C., pressure 2.0 kg / c).
m ² ).

The appearance of the obtained three-layer laminated film was observed, and the presence or absence of wrinkles or air was checked. As a result, it was confirmed that there was no wrinkles or air.

Comparative Example 1 In Example 1, an ordinary cylindrical roll was used in place of the banana roll, and a tension of 7.0 kgf was applied in the length direction to the EVA film without applying tension in the width direction to the PET film. Except for laminating, a two-layer laminated film was produced in the same manner.

When the appearance of the obtained two-layer laminated film was observed, it was found that wrinkles and air were mixed in and the product quality was poor.

[0043]

As described in detail above, according to the method for producing a laminated film of the present invention, it is possible to produce a laminated film free from wrinkles and air mixing.

The method for producing a laminated film according to the present invention is particularly applicable when the base film is made of a resin having a melting point higher than that of the thermoplastic resin, or another thermoplastic resin film is laminated and integrated on the non-laminated surface side. This is particularly effective when the film is formed into a two-layer film.

In the present invention, the thermoplastic resin film includes an EVA resin film containing a cross-linking agent. The present invention particularly relates to a laminated film such as EVA / PET / EVA as a film for a sealing film of a solar cell. Suitable for manufacturing.

[Brief description of the drawings]

FIG. 1A is a schematic plan view showing an embodiment of the present invention, and FIG. 1B is a side view thereof.

FIG. 2 is a cross-sectional view illustrating a general solar cell.

[Description of Signs] 1 Glass substrate 2 Back cover 3A, 3B Sealing film 4 Silicon power generation element 11, 14 Guide roll 12 Base film 13 Banana roll 15 Thermoplastic resin film 16, 17 Pressing roll 18 Laminated film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B29L 9:00 31:34 F term (Reference) 4F100 AK01A AK10C AK42 AK68A AK68C AT00B AT00C BA02 BA03 BA06 BA10A BA10C CA02A CA02C CA05 EH012 EJ382 GB41 JA04A JA04B JB16A JB16C JL00 4F211 AA10 AA24 AG01 AG03 AM26 AM32 TC05 TD11 TH16 TN81 TQ01 5F051 BA18 JA05

Claims (5)

[Claims] 1. A method of manufacturing a laminated film by laminating and integrating a thermoplastic resin film and a base film, wherein the base film is tensioned by applying tension in two axial directions, and the thermoplastic resin is stretched. A method for producing a laminated film, comprising laminating films. 2. The method according to claim 1, wherein the base film is made of a resin having a melting point higher than that of the thermoplastic resin. 3. The laminated film according to claim 1, wherein the base film is a two-layer film in which another thermoplastic resin film is laminated and integrated on the non-laminated surface side. Manufacturing method. 4. The method for producing a laminated film according to claim 1, wherein the thermoplastic resin film is an EVA resin film containing a crosslinking agent. 5. The method for producing a laminated film according to claim 1, wherein the laminated film is a film for a sealing film of a solar cell.