KR101696759B1 - Moisture protection properties superior back sheet and method for fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a back sheet having excellent moisture-preventing properties for preventing moisture from penetrating and a method for producing the same.
The backsheet having an excellent moisture-proofing property according to the embodiment of the present invention is a polyimide (PI) base film having excellent heat resistance; A first adhesive layer formed on one surface of the base film and having moisture-preventing and adhesive functions; A second adhesive layer formed on the other surface of the base film and having a moisture-preventing and adhesive function; A film formed of any one selected from among PFA (perfluoroalkoxy alkane), FEP (fluoronate ethylenepropylene) and ETFE (ethylene-tetrafluoroethylene) films and attached to the base film by the first adhesive layer; And a polyolefin (PO) -based film adhered to the base film by the second adhesive layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back sheet and a method of manufacturing the same, and more particularly, to a back sheet having excellent water-repellent property for preventing moisture from penetrating into a solar cell module and a method for manufacturing the same.

The technology to convert solar energy into electric energy using a medium called solar cell module has no mechanical or chemical action in the process of converting solar energy into electrical energy, so the structure of the system is simple, requiring little maintenance and long life Safe and environmentally friendly.

Such a solar cell module is formed by sequentially laminating a tempered glass, an upper ethylene vinyl acetate (EVA) film, a solar cell, a lower EVA film, and a back sheet, Lt; RTI ID = 0.0 > laminating < / RTI >

Here, the back sheet serves to waterproof, insulate and ultraviolet light shield the solar cell from the rear surface of the solar cell module, and also has excellent durability that can withstand high temperature and humidity in order to prolong the life of the solar cell module .

In general, a sheet used for packaging a solar cell should have a weather-resistant and durable back sheet to stably protect the solar cell even when exposed to an external environment for 20 years or more.

However, moisture penetration is the most critical factor in the lifetime of a solar cell module. If water penetrates into the solar cell module, oxidation of the solar cell, insulation breakdown due to leakage current, and the like result in lowered power generation efficiency and cause malfunction. Therefore, the solar cell module is required to have a water-repellent layer in order to prevent the penetration of moisture.

The backsheet developed so far uses an aluminum foil or aluminum evaporation-treated anti-moisture film, or an anti-evaporation film coated with an inorganic oxide.

However, since the aluminum foil or aluminum vapor-deposited moisture permeation preventive layer film has conductivity, power is leaked and insulation breakdown occurs as the solar cell module itself ages. Therefore, although it has the highest moisture-proofing function, it requires a separate insulation treatment process to prevent it, short life span, and causes a failure due to instantaneous discharge. Such a structure is disadvantageous in that the number of processes is large and complex, and the production cost is high.

Accordingly, there is a need for a back sheet for a solar cell having high durability and mechanical strength, and a new back sheet production process which is simple in process and high in productivity, It is true.

Published Patent Application No. 10-2010-0089038 Published Patent Application No. 10-2010-0105505

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a back sheet for protecting the back surface of a solar cell module, which has excellent moisture permeation prevention function and at the same time has high durability and mechanical strength, It has its purpose.

Another object of the present invention is to provide a method of manufacturing a back sheet which is simple in manufacturing process and can reduce manufacturing cost.

The backsheet having an excellent moisture-proofing property according to the embodiment of the present invention is a polyimide (PI) base film having excellent heat resistance; A first adhesive layer formed on one surface of the base film and having moisture-preventing and adhesive functions; A second adhesive layer formed on the other surface of the base film and having a moisture-preventing and adhesive function; A film formed of any one selected from among PFA (perfluoroalkoxy alkane), FEP (fluoronate ethylenepropylene) and ETFE (ethylene-tetrafluoroethylene) films and attached to the base film by the first adhesive layer; And a polyolefin (PO) -based film adhered to the base film by the second adhesive layer, wherein the first adhesive layer and the second adhesive layer each comprise isoprene (isoprene) or isobutylene Isobutylene), nano silica, ethylhexyl acrylate, a silane coupling agent having a number average molecular weight of 120 to 300, and an organic solvent such as ethylhexylmethoxycinnamate, isoamyl P-methoxy cinnamate, bis-ethyl At least one of hexyloxy phenol methoxy phenyl triazine, C12-15 alkyl benzoate, titanium oxide, aluminum stearate, polyhydroxystearic acid, alumina and ethylhexyl salicylate.

In addition, in the embodiment of the present invention, a method of manufacturing a back sheet includes: providing a polyimide (PI) base film having excellent heat resistance; A first step of applying a mixture containing a thermosetting polyurethane resin on one surface of the base film to form a first adhesive layer having moisture-preventing and adhesive function, and then drying the first adhesive layer; A second step of attaching a film made of one selected from PFA (Perfluoroalkoxy Alkane), FEP (fluoronate ethylenepropylen) and ETFE (Ethylene-Tetrafluoroethylene) film to the first adhesive layer; A third step of applying the mixture on the other surface of the base film to form a second adhesive layer having moisture-preventing and adhesive function, and then drying the second adhesive layer; A fourth step of attaching a polyolefin (PO) based film to the second adhesive layer; And a fifth step of aging the back sheet completed in the fourth step at 40 to 60 DEG C for 70 to 100 hours, wherein the mixture of the first adhesive layer and the second adhesive layer comprises a thermosetting polyurethane resin Isoprene, isobutylene, nano silica, ethylhexyl acrylate, a silane coupling agent having a number average molecular weight of 120 to 300, ethylhexylmethoxy cinnamate, isoamyl P At least one of methoxycinnamate, bis-ethylhexyloxyphenol methoxyphenyltriazine, C12-15 alkylbenzoate, titanium oxide, aluminum stearate, polyhydroxystearic acid, alumina and ethylhexyl salicylate Or more.

The back sheet for a solar cell according to the present invention has the following effects.

According to the present invention, it is possible to produce an excellent back sheet exhibiting excellent durability and mechanical strength while having excellent moisture permeation prevention characteristics.

Further, according to the present invention, it is possible to provide a back sheet excellent in hardness, durability, weather resistance, heat resistance and adhesion.

1 is a cross-sectional view of a back sheet for a solar cell according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a back sheet for a solar cell according to an embodiment of the present invention.

Referring to FIG. 1, a back sheet 100 according to an embodiment of the present invention includes a first adhesive layer 130 and a second adhesive layer 150 having high moisture-preventing properties on both surfaces of a base film 110 A fluorine-based film 170 and a polyolefin (PO) based film 190 are formed on the outer surfaces of the first adhesive layer 130 and the second adhesive layer 150, respectively. The first adhesive layer 130 and the second adhesive layer 150 have excellent moisture barrier properties and also have a role of firmly attaching the fluorine-based film 170 and the polyolefin (PO) based film 190 to the base film 110 .

The base material film 110 in the center is a polyester film which is made of polyether terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyimide (PI) A polyethylene terephthalate (PET) film which is superior in physical properties to heat resistance and moisture resistance in comparison with a double other film is preferable, and it is more preferable to use a low oligomer PET film having excellent heat resistance among them. However, But is not limited thereto.

The first adhesive layer 130 and the second adhesive layer 150 simultaneously have an excellent moisture-preventing function and an adhesive function. The first and second adhesive layers 130 and 150 are preferably made of a thermosetting polyurethane resin as a base resin and are mixed with a rubber based resin having an anti-moisture property, an inorganic filler, an adhesion promoter, and a curing agent. In another embodiment, at least one of ultraviolet light blocking agent, leveling agent, dispersant, and solvent may be optionally used alone or in combination.

Specific examples of the thermosetting polyurethane resin include polyurethane polyol and derivatives thereof, polyamide amine, polyurea and derivatives thereof, and examples of the rubber resin include butadiene, styrene, isoprene, Isobutylene rubber or the like is used, but butyl rubber such as butyl rubber, styrene butadiene rubber, and nitrile budadiene is preferable.

The organic or inorganic filler having water-repellent properties is an organic or inorganic hybrid type prepared by a sol-gel method and is formed by reacting nano silica with a hydrophobic organic resin on its surface. Examples of the organic resin include butyl acrylate, ethylhexyl acrylate and hydroxyethyl methacrylate (HEMA), among which butyl acrylate is preferable. Do.

As the adhesion promoting agent, a silane coupling agent may be used. Such a silane coupling agent may be a low molecular weight silane compound having a number average molecular weight of 120 to 550, preferably 120 to 300, and preferably, aminopropyltrimethoxysilane , Aminoethylmethoxypropyltrimethoxysilane, aminoethylmethaminopropyltriethoxysilane, trimethoxysilylpropyltriethoxysilane, benzylethylenediaminepropyltriethoxysilane monohydrochloride, vinylbenzyl Silane such as ethylenediaminepropyltriethoxysilane, benzylethylenediaminepropyltrimethoxysilane monohydrochloride, benzylethyleneiminopropyltrimethoxysilan, and ethylenediaminepropyltrimethoxysilanemonohydrochlorideaminosilane may be used in an amount of 1 More than one species can be used, singly or in combination.

In addition to the thermosetting resin, the curing agent is used to promote or control the curing reaction, and amines, polyamides, and the like are used.

As the ultraviolet screening agent, an organic ultraviolet screening agent having an ultraviolet ray absorbing effect can be used. Specific examples thereof include ethylhexylmethoxycinnamate, isoamyl P-methoxy cinnamate, bis-ethylhexyloxyphenol methoxyphenyltriazine, C12-15 alkyl benzoate, titanium oxide, aluminum stearate, polyhydroxystearic acid, alumina, and ethylhexyl salicylate. The ultraviolet screening agent used in the present invention may be titanium dioxide, In addition, zinc oxide and the like can be used. The ultraviolet screening agent can be used by adjusting its content according to a desired ultraviolet screening effect.

The leveling agent is an additive added to the smooth surface of the coating layer and the adhesion to the substrate film. The product and the characteristics of each material are as shown in the following items a) and b).

end). Polyether modified polydimethylsiloxane < RTI ID = 0.0 >

- Characteristic: It greatly reduces the surface tension, increases wetting of the material, and gives both slip and leveling.

- Products: BYK-302 (BYK), BaysilonePaint Additive 3466 (Borchers)

I). Polymeric fluorosurfactant

- Characteristics: Excellent leveling property and material wettability.

- Products: BYK-340 (BYK), FC-4430 (3M), ZonylFSN-100 (Du Pont)

The leveling agent is used alone or as a mixture of the above three types. Particularly, the polydimethylsiloxane-based leveling agent bonds with the acrylate of the UV-curable resin on the surface to effectively improve the slip property and the water resistance among the surface properties of the coating layer, Thereby enhancing the maintenance stability of surface physical properties.

The dispersant is added for uniform dispersion of the organic and inorganic fillers. Actual products and characteristics are as shown in (a) and (b) below.

end). A high molecular weight block copolymer with groups of pigments affinity.

- Products: BYK-168 (BYK)

I). Modified polyether with groups of high pigments affinity containing high pigment affinity functional groups

- Product: TEGODispers 656 (Evonik Degussa)

Methyl ethyl ketone (MEK), toluene, ethylacetate (EA), cyclohexanone, BA (buthyl acetate) and the like may be used as a solvent for the purpose of imparting appropriate viscosity and coating properties to the coating.

The present invention will now be described in detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

1. Experimental conditions

(1) In Examples 1 and 2, a rubber-based resin having 25 to 30 parts by weight based on 100 parts by weight of the adhesive, an organic-inorganic filler having 8 parts by weight and an adhesion promoting agent having 2 parts by weight were stirred.

(2) Rubber-based resin was not used in Comparative Example 1, no organic filler was used in Comparative Example 2, and no adhesion promoting agent was used in Comparative Example 3.

More detailed experimental conditions are shown in Table 1.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Adhesive (wt%) 100 100 100 100 100 Rubber Resin (wt%) 30 25 - 30 30 Inorganic filler (wt%) 8 8 8 - 8 Adhesion promoter (wt%) 2 2 2 2 - Ultraviolet absorber (wt%) 3.4 3.4 3.4 3.4 3.4 Leveling agent (wt%) 0.4 0.4 0.4 0.4 0.4 Dispersant (wt%) 2.1 2.1 2.1 2.1 2.1 Solvent (wt%) 14 14 14 14 14 Water permeability g / (m2 · day) 0.8 1.2 25 12 0.9 Adhesive force between the base film and the fluorine film (kg / 25 mm) 6.3 6.2 6.2 6.1 2.2

2. Water Permeability

The test specimens were measured according to ASTM F1249 at 38 DEG C and 100% RH.

3. Adhesive force between the base film 110 and the fluorine film 170 was prepared by preparing five test specimens of 25 mm in width per each sample, leaving the sample in a room temperature atmosphere at room temperature. The adhesive force was measured at a peel angle of 180 degrees, a peel rate of 300 mm / min, and a room temperature (24 DEG C).

As described above, in the backsheet according to the present invention, the two-layer heat-resistant, moisture-proof, mechanical, and the like can be formed by the organic-inorganic hybrid technology (technology for simultaneously realizing processability and mechanical / The present invention can be applied to the photovoltaic power generation industry such as improving the back sheet supply situation which does not satisfy the demand for the present solar cell module by lowering the manufacturing cost by simplifying the manufacturing process of the back sheet and reducing the cost .

110: base film 130: first adhesive layer
150: second adhesive layer 170: fluorine-based film
190: PO-based film

Claims (20)

A polyimide (PI) base film having excellent heat resistance;
A first adhesive layer formed on one surface of the base film and having moisture-preventing and adhesive functions;
A second adhesive layer formed on the other surface of the base film and having a moisture-preventing and adhesive function;
A film formed of any one selected from among PFA (perfluoroalkoxy alkane), FEP (fluoronate ethylenepropylene) and ETFE (ethylene-tetrafluoroethylene) films and attached to the base film by the first adhesive layer; And
A polyolefin (PO) -based film adhered to the base film by the second adhesive layer; / RTI >
Wherein the first adhesive layer and the second adhesive layer each comprise a thermosetting polyurethane resin as a base resin, isoprene or isobutylene, nano silica, ethylhexyl acrylate, and a number average molecular weight of 120 To 300 silane coupling agents and at least one compound selected from the group consisting of ethylhexylmethoxy cinnamate, isoamyl P-methoxy cinnamate, bis-ethylhexyloxyphenol methoxyphenyltriazine, C12-15 alkyl benzoate, titanium oxide, And a mixture of at least one of polyvinyl alcohol, polyoxyethylene stearate, polyhydroxy stearic acid, alumina and ethylhexyl salicylate. delete delete delete delete delete delete delete delete The method according to claim 1, wherein the silane coupling agent is selected from the group consisting of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylmonompropyltrimethoxysilane, aminoethylmonompropyltriethoxysilane, trimethoxysilylpropyltri Benzylethylenediaminepropyltriethoxysilane monohydrochloride, vinylbenzylethylenediaminepropyltriethoxysilane, benzylethylenediaminepropyltrimethoxysilane monohydrochloride, benzylethyleneiminopropyltrimethoxysilane, allyltriethoxysilane, benzylethylenediaminepropyltrimethoxysilane, Ethylenediaminepropyltrimethoxysilane monohydrochloride aminosilane, or a combination of at least two of them. delete delete delete The backsheet according to claim 1, wherein the polyolefin (PO) -based film comprises linear low-density polyethylene (LLDPE). Providing a polyimide (PI) base film having excellent heat resistance;
A first step of applying a mixture containing a thermosetting polyurethane resin on one side of the base film to form a first adhesive layer having moisture-preventing and adhesive function, and then drying the first adhesive layer;
A second step of attaching a film made of one selected from PFA (Perfluoroalkoxy Alkane), FEP (fluoronate ethylenepropylen) and ETFE (Ethylene-Tetrafluoroethylene) film to the first adhesive layer;
A third step of applying the mixture to the other surface of the base film to form a second adhesive layer having moisture-preventing and adhesive function, and drying the second adhesive layer;
A fourth step of attaching a polyolefin (PO) based film to the second adhesive layer; And
A fifth step of aging the backsheet completed at the fourth step at 40 to 60 DEG C for 70 to 100 hours; Lt; / RTI >
Wherein the mixture of the first adhesive layer and the second adhesive layer is a mixture of isoprene or isobutylene, nano silica, ethylhexyl acrylate, and a number average molecular weight The silane coupling agent having a weight average molecular weight of 120 to 300 and the silane coupling agent having an average molecular weight of from 200 to 300 are mixed with ethylhexylmethoxycinnamate, isoamyl P-methoxy cinnamate, bis-ethylhexyloxyphenol methoxyphenyltriazine, C12-15 alkylbenzoate, Aluminum stearate, polyhydroxystearic acid, alumina, and ethylhexyl salicylate are mixed with each other. delete delete delete delete 16. The method of claim 15, wherein the silane coupling agent is selected from the group consisting of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylmonompropyltrimethoxysilane, aminoethylmonompropyltriethoxysilane, trimethoxysilylpropyltri Benzylethylenediaminepropyltriethoxysilane monohydrochloride, vinylbenzylethylenediaminepropyltriethoxysilane, benzylethylenediaminepropyltrimethoxysilane monohydrochloride, benzylethyleneiminopropyltrimethoxysilane, allyltriethoxysilane, benzylethylenediaminepropyltrimethoxysilane, Ethylenediaminepropyltrimethoxysilane monohydrochloride aminosilane silane, or a mixture thereof.

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