KR20130138266A - Photovoltaic cell backsheet and photovoltaic cell module - Google Patents

Abstract

This invention is a solar cell backsheet arrange | positioned at the back side (optical side opposite to a light receiving surface) of a solar cell element, Comprising: A liquid crystal polyester layer and a white pigment containing layer are provided, The white pigment containing layer is provided in the back side of a liquid crystal polyester layer. It is related with the solar cell backsheet formed, and the solar cell module formed using this.

Description

Solar cell backsheet and solar cell module {PHOTOVOLTAIC CELL BACKSHEET AND PHOTOVOLTAIC CELL MODULE}

The present invention relates to a solar cell backsheet having a liquid crystalline polyester layer. Moreover, this invention relates to the solar cell module which uses this solar cell back sheet.

The solar cell module usually has a structure in which a surface protective sheet is arranged on the front side (light receiving surface side) of the solar cell element, and a back sheet is arranged on the back side (opposite side of the light receiving surface). And the example is shown in FIG. In this example, the solar cell element 3 is encapsulated with the encapsulation layer 2 on the front side and the encapsulation layer 4 on the back side, and the surface protective sheet 1 is provided on the outer side (surface) of the encapsulation layer 2 on the front side. It arrange | positions and the back seat | sheet 5 is arrange | positioned at the outer side (back side) of the sealing layer 4 of this side. In addition, the peripheral edges of the surface protective sheet 1 and the back sheet 5 are fixed by the frame 6.

Patent document 1 and 2 disclose using a liquid crystal polyester film from a point which is excellent in water vapor barrier property for a back sheet. Moreover, it is also disclosed by patent document 2 to laminate | stack a resin film in the inside (front side) of a liquid crystal polyester film, and to use this laminated film as a back sheet.

Japanese Unexamined Patent Publication No. 2002-64213 Japanese Laid-Open Patent Publication 2006-324478

As for the backsheet for solar cells which has the conventional liquid crystal polyester layer as disclosed in patent document 1 and patent document 2, weather resistance may not necessarily be enough. Then, the objective of this invention is providing the solar cell backsheet which has a liquid crystalline polyester layer and is excellent in weatherability enough.

MEANS TO SOLVE THE PROBLEM In order to achieve the said objective, this invention is a solar cell backsheet arrange | positioned at the back side of a solar cell element, Comprising: A liquid crystal polyester layer and a white pigment containing layer are provided, A white pigment containing layer is formed in the back side of a liquid crystal polyester layer, Provided is a solar cell back sheet.

Moreover, this invention also provides the solar cell module by which the surface protection sheet is arrange | positioned at the front side of a solar cell element, and the said solar cell back sheet is arrange | positioned at the back side of the said solar cell element.

The solar cell backsheet of the present invention is sufficiently excellent in weather resistance.

1 is a cross-sectional view schematically showing an example of a solar cell module.
FIG. 2: is sectional drawing which shows typically the example of the solar cell backsheet of this embodiment.

As for the solar cell backsheet of this embodiment, as shown in FIG. 2, the white pigment containing layer 56 is formed in the back side (opposite side to the surface on which the solar cell element is mounted) of the liquid-crystal polyester layer 53, As shown in FIG. 1, it is arrange | positioned at the back side (surface side opposite to a light receiving surface) of the solar cell element 3.

It is preferable that liquid crystalline polyester which comprises the liquid crystal polyester layer 53 is melted at the temperature of 450 degrees C or less as polyester which shows liquid crystallinity in a molten state. Moreover, liquid crystalline polyester may be sufficient as liquid crystal polyester, liquid crystalline polyester ether may be sufficient, liquid crystalline polyester carbonate may be sufficient, and liquid crystalline polyester imide may be sufficient as it. It is preferable that liquid crystalline polyester is all aromatic liquid crystalline polyester which uses only an aromatic compound as a raw material monomer.

Typical examples of liquid crystalline polyesters are those obtained by polymerizing (polycondensation) at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines and aromatic diamines. A polymer obtained by polymerizing a plurality of aromatic hydroxycarboxylic acids, an aromatic dicarboxylic acid, and polymerizing at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines, And what is formed by superposing | polymerizing polyester, such as polyethylene terephthalate, and aromatic hydroxycarboxylic acid is mentioned. Here, the derivative which can superpose | polymerize an aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine, and aromatic diamine may be used independently instead of one part or all, respectively.

Examples of the polymerizable derivative of a compound having a carboxyl group such as an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group, converting a carboxyl group into a haloformyl group, And those obtained by converting a carboxyl group to an acyloxycarbonyl group. Examples of the polymerizable derivative of a compound having a hydroxyl group such as an aromatic hydroxycarboxylic acid, an aromatic diol, and an aromatic hydroxyamine include those obtained by acylating a hydroxyl group and converting it into an acyloxyl group. Examples of the polymerizable derivative of the compound having an amino group such as aromatic hydroxyamine and aromatic diamine include those obtained by acylating an amino group and converting it into an acylamino group.

As liquid crystalline polyester, since it is excellent in water vapor barrier property, the repeating unit represented by following formula (1) (hereinafter may be called "repeating unit (1)"), and the repeating unit represented by following formula (2) (Hereinafter, it may be called "repeating unit (2).) And what has a repeating unit represented by following formula (3) (Hereinafter, it may be called" repeating unit (3). ") Is used preferably. .

-O-Ar ¹ -CO- (1)

-CO-Ar ² -CO- (2)

-O-Ar ³ -O- (3)

Ar ¹ represents a 2,6-naphthylene group, a 1,4-phenylene group or a 4,4'-biphenylylene group. Ar ² and Ar ³ each independently represent a 2,6-naphthylene group, a 1,4-phenylene group, a 1,3-phenylene group or a 4,4'-biphenylylene group. In the hydrogen atom in the said group represented by Ar <^1> , Ar <^2> or Ar <^3> , ie, a 2, 6- naphthylene group, a 1, 4- phenylene group, a 1, 3- phenylene group, or a 4, 4'- biphenylylene group The hydrogen atoms of may be each independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, n -Octyl group and n-decyl group are mentioned, The carbon number is 1-10 normally. Examples of the aryl group include a phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group and 2-naphthyl group, and the carbon number thereof is usually 6 to 20. When the said hydrogen atom is substituted by these groups, the number is each independently 2 or less normally for each said group represented by Ar <^1> , Ar <^2> or Ar <^3> , Preferably it is 1 or less.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), ^{one in} which Ar ¹ is a 2,6-naphthylene group, that is, a repeating unit derived from 6-hydroxy-2-naphthoic acid is preferable.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a 2,6-naphthylene group, that is, a repeating unit derived from 2,6-naphthalenedicarboxylic acid, and Ar ² is a 1,4-phenylene group, that is, terephthalic acid The repeating unit derived from is preferable.

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol. As the repeating unit (3), Ar ³ is a 1,4-phenylene group, that is, a repeating unit derived from hydroquinone, and Ar ³ is a 4,4'-biphenylylene group, that is, 4,4'- Repeating units derived from dihydroxybiphenyl are preferred.

In the liquid crystal polyester layer according to the present embodiment, at least one of the repeating units represented by the formulas (1), (2) and (3) each contains a 2,6-naphthylene group, and the 2,6-naphthylene group It is preferable that content of the repeating unit to include is a layer comprised from the liquid crystalline polyester which is 40 mol% or more with respect to the total amount of all the repeating units.

The content of the repeating unit including a group of the liquid-crystalline polyester, 2,6-naphthylene, that is, Ar ¹ is 2,6-naphthylene group repeating unit (1), Ar ² is 2,6-naphthylene group repeating unit The total content of the repeating unit (3) in which (2) and Ar ³ is a 2,6-naphthylene group is obtained by dividing the total amount of all the repeating units (the mass of each repeating unit constituting the liquid crystal polyester by the food content of each repeating unit). It is preferable that it is 40 mol% or more with respect to the value which calculated | required the equivalent amount (mol) of substance of each repeating unit, and totaled them. Thereby, a water vapor barrier property can be improved. Content of this 2, 6- naphthylene group becomes like this. More preferably, it is 50 mol% or more, More preferably, it is 60 mol% or more, Especially preferably, it is 70 mol% or more.

Moreover, content of a repeating unit (1) in the said liquid crystalline polyester becomes like this. Preferably it is 30-80 mol% with respect to the total amount of all the repeating units, More preferably, it is 40-70 mol%, More preferably, it is 45-65 Mol%. Moreover, content of the repeating unit (2) becomes like this. Preferably it is 10-35 mol%, More preferably, it is 15-30 mol%, More preferably, it is 17.5-27.5 mol% with respect to the total amount of all the repeating units. Moreover, content of the repeating unit (3) becomes like this. Preferably it is 10-35 mol%, More preferably, it is 15-30 mol%, More preferably, it is 17.5-27.5 mol% with respect to the total amount of all the repeating units. The liquid crystal polyester which has such a predetermined repeating unit composition is excellent in the balance of heat resistance and moldability. In addition, it is preferable that content of the repeating unit (2) and content of the repeating unit (3) are substantially equivalent. Moreover, although the said liquid crystal polyester may have repeating units other than repeating units (1)-(3) as needed, the content is 10 mol% or less normally with respect to the total amount of all the repeating units, Preferably it is 5 It is mol% or less.

Typical examples of the liquid crystal polyester having high heat resistance and high melt tension are derived from a repeating unit (1) in which Ar ¹ is a 2,6-naphthylene group, that is, 6-hydroxy-2-naphthoic acid, based on the total amount of all the repeating units. Preferably the repeating unit to make is 40-74.8 mol%, More preferably, it is 40-64.5 mol%, More preferably, it is 50-58 mol%, The repeating unit (2) whose Ar <^2> is a ² , 6- naphthylene group, i.e., 2,6-naphthalenedicarboxylic acid having preferably from 12.5 to 30 mol% of repeating units derived from a, more preferably from 17.5 to 30 mol%, more preferably 20 to 25 mol%, and Ar ² is 1 It is a repeating unit (2) which is a 4-phenylene group, ie, the repeating unit derived from terephthalic acid, Preferably it is 0.2-15 mol%, More preferably, it is 0.5-12 mol%, More preferably, it has 2-10 mol%, Repeating unit (3) wherein Ar ³ is a 1,4-phenylene group, that is, a repeating unit derived from hydroquinone Preferably 12.5-30 mol%, More preferably, it is 17.5-30 mol%, More preferably, it is 20-25 mol%, and content of the repeating unit (2) whose Ar2 is a ² , 6- naphthylene group is , With respect to the total content of the repeating unit (2), wherein Ar ² is a 2,6-naphthylene group and the repeating unit (2), wherein Ar ² is a 1,4-phenylene group, preferably 0.5 mole times or more, and more preferably 0.6 More than a mole.

It is preferable to manufacture liquid crystal polyester by melt-polymerizing a monomer and carrying out solid-phase polymerization of the obtained polymer (prepolymer). Thereby, liquid crystal polyester with high heat resistance and high melt tension can be manufactured with good operability. Melt polymerization may be performed in the presence of a catalyst. Examples of this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, and N, N-dimethylaminopyridine and N-methylimidazole. Nitrogen-containing heterocyclic compounds, such as these, are mentioned, A nitrogen-containing heterocyclic compound is used preferably.

The flow start temperature of the liquid crystalline polyester is preferably 280 ° C or higher, more preferably 290 ° C or higher, even more preferably 295 ° C or higher, and usually 380 ° C or lower, preferably 350 ° C or lower. The higher the flow start temperature is, the easier it is to improve heat resistance and melt tension. However, when the flow start temperature is too high, a high temperature is required for melting, and heat deterioration is easily performed during molding.

In addition, a flow start temperature is also called a flow temperature or a flow temperature, and it raises the temperature of 4 degree-C / min under the load of 9.8 Mpa (100 kg / cm <2>) using the capillary rheometer which has a nozzle of internal diameter 1mm and length 10mm. When extruding the heated melt of liquid crystal polyester from the nozzle at a speed, the melt viscosity is a temperature of 4800 Pa · s (48000 poise), and serves as a reference for the molecular weight of the liquid crystal polyester. -Synthesis, Molding, and Application, "CMC, June 5, 1987, p. 95).

It is good also as a composition to mix | blend another component with liquid crystalline polyester as needed. As an example of another component, filler, thermoplastic resins other than liquid crystalline polyester, and an additive are mentioned. The ratio of the liquid crystalline polyester in the whole composition becomes like this. Preferably it is 80 mass% or more, More preferably, it is 90 mass% or more.

Examples of the filler include glass fibers such as milled glass fibers and chopped glass fibers, potassium titanate whiskers, alumina whiskers, aluminum borate whiskers, silicon carbide whiskers and silicon nitride whiskers, glass beads, hollow glass balls, Glass powder, mica, talc, clay, silica, alumina, potassium titanate, wallaceite, calcium carbonate (heavy, hard, colloidal, etc.), magnesium carbonate, basic magnesium carbonate, soda sulfate, calcium sulfate, barium sulfate, calcium sulfite, hydroxide Aluminum, magnesium hydroxide, calcium hydroxide, calcium silicate, silica sand, silica, quartz, titanium oxide, zinc oxide, iron oxide graphite, molybdenum, asbestos, silica alumina fiber, alumina fiber, gypsum fiber, carbon fiber, carbon black, white carbon, diatomaceous earth , Bentonite, sericite, syras, and graphite, and two of them as necessary. You may use the award. Among them, glass fibers, mica, talc, and carbon fibers are preferably used as the filler.

The filler may be surface treated as needed. Examples of the surface treatment agent include reactive coupling agents such as silane coupling agents, titanate coupling agents, and borane coupling agents, and lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants. Can be mentioned.

Examples of thermoplastic resins other than liquid crystalline polyester include polycarbonate, polyamide, polysulfone, polyphenylene sulfide, polyphenylene ether, polyether ketone, and polyetherimide resin.

Examples of the additive include release modifiers such as fluororesins and metal soaps, nucleating agents, antioxidants, stabilizers, plasticizers, lubricants, anti-colorants, colorants, ultraviolet absorbers, antistatic agents, lubricants and flame retardants.

The liquid crystal polyester film used as the liquid crystal polyester layer 53 of the solar cell backsheet of this embodiment can be obtained by film-forming the liquid crystal polyester obtained or a composition thereof in this way. Examples of the film forming method include an extrusion molding method, a press molding method, a solution casting method, and an injection molding method, and an extrusion molding method is preferable. As the extrusion method, for example, a T-die method or an inflation method may be mentioned. In the T-die method, uniaxial stretching or biaxial stretching may be performed.

The draw ratio (draft ratio) of a uniaxial stretched film is 1.1-40 normally, Preferably it is 10-40, More preferably, it is 15-35. The draw ratio in the MD direction (extrusion direction) of the biaxially stretched film is usually 1.2 to 40 times, and the draw ratio in the TD direction (direction perpendicular to the extrusion direction) of the biaxially stretched film is usually 1.2 to 20 times. The draw ratio in the MD direction of the inflation film (draw-down ratio = bubble take-up speed / resin discharge rate) is usually 1.5 to 50, preferably 5 to 30, and the draw ratio of TD of the inflation film (blow ratio = bubble diameter /). Cyclic slit diameter) is usually 1.5 to 10, preferably 2 to 5.

Preferably the thickness of the liquid-crystal polyester layer 53 is 5-100 micrometers, More preferably, it is 10-75 micrometers, More preferably, it is 15-75 micrometers. Too thin will result in insufficient strength, and too thick will result in insufficient flexibility.

It is preferable that the water vapor transmission rate measured at the temperature of 40 degreeC, and 90% of a relative humidity of the liquid-crystal polyester layer 53 is 0.1 g / m <2> * 24h or less, and it is more preferable that it is 0.05 g / m <2> * 24h or less.

The vapor barrier layer 54 may be formed in the liquid crystal polyester layer 53 on at least one surface thereof. In addition, in the example of FIG. 2, although the water vapor barrier layer 54 is formed in the back side of the liquid-crystal polyester layer 53, it is formed in the front side (surface side on which the solar cell element is mounted) of the liquid-crystal polyester layer 53, It may be present and may be provided in the front side and the back side of the liquid crystal polyester layer 53.

Examples of the material constituting the water vapor barrier layer 54 include a single element, an oxide, at least one element selected from the group consisting of aluminum, silicon, titanium, chromium, iron, cobalt, nickel, copper, zinc, silver, and gold. Nitrides and oxynitrides are preferred, and two or more kinds thereof may be used as necessary. That is, the water vapor barrier layer 54 is a single element of an element selected from the group (A), an oxide of an element selected from the group (A), a nitride of an element selected from the group (A), and the following (A) It is preferable that it is a layer which consists of at least 1 sort (s) of substance chosen from the group which consists of oxynitride of the element chosen from the group.

(A) group: aluminum, silicon, titanium, chromium, iron, cobalt, nickel, copper, zinc, silver or gold.

As a method of forming the water vapor barrier layer 54, for example, a PVD method such as a vapor deposition method, a sputtering method, an ion plating method, a CVD method such as a plasma CVD method, a thermal CVD method, a laser CVD method, and a sol-gel method, Wet methods, such as a plating method and a coating method, are mentioned. Moreover, you may bond together the liquid crystal polyester film prepared and obtained separately.

The thickness of the water vapor barrier layer 54 is preferably 5 to 250 nm, more preferably 40 to 100 nm. When too thin, the effect of improving the water vapor barrier property is insufficient, and when too thick, the flexibility is insufficient.

On the back side of the liquid crystal polyester layer 53, a white pigment-containing layer 56 is formed. Thereby, the solar cell backsheet excellent in weatherability can be obtained. In addition, in the example of FIG. 2, although the white pigment containing layer 56 is formed through the contact bonding layer 55, the white pigment containing layer 56 is formed, for example by thermal fusion, without the bonding layer 55 interposed. You may be.

As a white pigment contained in the white pigment-containing layer 56, basic lead carbonate _{(2PbCO 3 · Pb (OH)} 2 ( white lead (鉛白)), etc.), basic lead sulfate _{(2PbSO 4 · Pb (OH)} 2 , etc.) , basic lead silicate _{(Pb 2 SiO 4 · Pb (} OH) 2 and the like), zinc white (ZnO (zinc oxide)), zinc sulfide, lithopone (a mixture of zinc sulfide and barium sulfate), antimony trioxide and titanium are preferred oxidation and In addition, you may use 2 or more types of them as needed.

The white pigment containing layer 56 can be formed using the resin film containing a white pigment. As resin contained in this resin film, ie, the white pigment containing layer 56, polyester, such as a polyethylene terephthalate (PET), is preferable. The content of the white pigment in the white pigment-containing layer 56 is preferably 5 to 90 mass%, more preferably 10 to 80 mass% with respect to the total amount of the white pigment-containing layer 56. Moreover, the thickness of the white pigment containing layer 56 becomes like this. Preferably it is 5-500 micrometers, More preferably, it is 10-400 micrometers.

Another resin layer, preferably the polyolefin layer 51 may be formed on the front side of the liquid crystal polyester layer 53 in order to enhance the adhesiveness to the sealing layer 4 and to provide designability. In addition, in the example of FIG. 2, although the polyolefin layer 51 is formed through the contact bonding layer 52, the polyolefin layer 51 may be formed, for example by heat fusion, not through the contact bonding layer 52. FIG. .

The polyolefin constituting the polyolefin layer 51 is preferably polyethylene, more preferably low density polyethylene (LDPE), still more preferably linear low density polyethylene (LLDPE). It is preferable to form the polyolefin layer 51 using a polyolefin film, and when forming the polyolefin layer 51 in order to provide designability, the polyolefin film 51, ie, a pigment or dye of a desired color, is added to the polyolefin layer 51. It is good to contain it. Preferably the thickness of the polyolefin layer 51 is 5-200 micrometers, More preferably, it is 10-100 micrometers.

The solar cell backsheet of this embodiment obtained in this way can form the sealing layer 4 in the front side, and can also take the product form of the solar cell backsheet in which the sealing layer was formed. In addition, in this case, the front side (surface side opposite to a back sheet) of the sealing layer 4 is normally protected by a peeling film, and a peeling film peels at the time of use (at the time of solar cell module manufacture).

In the solar cell module which uses the solar cell backsheet of this embodiment, as shown in FIG. 1, the surface protection sheet 1 is arrange | positioned at the front side (light receiving surface side) of the solar cell element 3, and a solar cell element The solar cell backsheet 5 of this embodiment is arrange | positioned at the back side (surface side opposite to a light receiving surface) of the present invention.

The solar cell element 3 is usually comprised with the several solar cell, the conducting wire which connects solar cells, and the conducting wire which connects a solar cell and a terminal box for power supply extraction. The solar cell may be a single crystal silicon semiconductor, a polycrystalline silicon semiconductor, an amorphous silicon semiconductor, a compound semiconductor, or an organic material semiconductor. As the surface protection sheet 1, a glass plate is used preferably. Moreover, it is preferable that the solar cell element 3 is sealed by the sealing material. As this sealing material, ethylene-vinyl acetate copolymer (EVA) is used preferably. In addition, in the example of FIG. 1, the sealing layers 2 and 4 are formed in the front side and the back side of the solar cell element 3, but when the solar cell element is arrange | positioned directly on the back surface of a glass plate, the sealing of this side It is only necessary to form the layer 4.

Since the solar cell module of this embodiment obtained in this way is equipped with the back seat | sheet fully excellent in weatherability, it is excellent in the durability of performance.

Example

[Measurement of Flow Start Temperature]

About 2 g of the sample was filled into a capillary rheometer equipped with a die having an internal diameter of 1 mm and a length of 10 mm using a flow tester (“CFT-500 type” manufactured by Shimadzu Corporation), and weighed 9.8 MPa (100 kg). The sample was extruded while melting the sample at a temperature increase rate of 4 ° C / min under a load of f / cm 2), and the temperature at which the melt viscosity exhibited 4800 Pa · s (48000 poise) was measured.

[Evaluation of Vapor Barrier Properties]

In accordance with JIS K 7126 (Method A: Differential Pressure Method), water vapor permeability is measured under conditions of a temperature of 40 ° C. and a relative humidity of 90% by means of a gas permeability and moisture permeability measuring device (“GTR-10X” of GTR Tech Co., Ltd.). It was.

[Evaluation of Weather Resistance]

Using an accelerated light resistance tester ("Strong Energy Xenon Weather Meter SC700-WN" of Suga Tester Co., Ltd.), xenon irradiation was performed on the backsheet under the following conditions, and the appearance of the backsheet was visually observed.

Wavelength: 275 nm or more continuous light (cut short wavelength side by filter)

Intensity: 160 W / ㎡ (lamp output)

Temperature: 65 ℃ (measured by flat panel thermometer at the same position as the irradiation surface)

Time: 60 hours

Production Example 1

1034.99 g (5.5 mol) of 6-hydroxy-2-naphthoic acid, 378.33 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid in a reactor equipped with a stirring device, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser ), 83.07 g (0.5 mole) of terephthalic acid, 272.52 g of hydroquinone (2.475 mole: 0.225 molar excess relative to the total amount of 2,6-naphthalenedicarboxylic acid and terephthalic acid), 1226.87 g (12 mole) of acetic anhydride, and as a catalyst 0.17 g of 1-methylimidazole was added thereto, the gas in the reactor was replaced with nitrogen gas, and the temperature was raised from room temperature to 145 ° C. over 15 minutes while stirring under a nitrogen gas stream, and the mixture was refluxed at 145 ° C. for 1 hour. Subsequently, by-product acetic acid and unreacted acetic anhydride were distilled off, heating up from 145 degreeC to 310 degreeC over 3 hours and 30 minutes, hold | maintaining at 310 degreeC for 3 hours, and the contents were taken out and cooled to room temperature. The resulting solids were pulverized with a particle size of about 0.1 to 1 mm, and then heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, heated up from 250 ° C. to 310 ° C. over 10 hours, and held at 310 ° C. for 5 hours. Solid phase polymerization was performed. It cooled after solid state superposition | polymerization and obtained powdery liquid crystalline polyester. This liquid crystalline polyester has 55 mol% of repeating units (1) whose Ar <^1> is a 2, 6- naphthylene group with respect to the total amount of all the repeating units, and Ar <^2> has a repeating unit (2) whose ² , 6- naphthylene groups. 17.5 mol%, and Ar ² is 1,4-phenylene group, repeat units is 2 to 5 mol%, and Ar ³ have a 1,4-phenylene group of the recurring unit (3) 22.5%, its flow starting temperature is It was 333 degreeC.

Production Example 2

911 g (6.6 mol) of p-hydroxybenzoic acid, 91 g (0.55 mol) of isophthalic acid, 274 g (1.65 mol) of terephthalic acid, 409 g of 4,4'-dihydroxybiphenyl (2.2) in the same reactor as Preparation Example 1 Mole), 1235 g (12.1 mole) acetic anhydride, and 0.17 g of 1-methylimidazole as a catalyst were added, and the gas in the reactor was replaced with nitrogen gas, followed by stirring under a nitrogen gas stream for 15 minutes at room temperature to 150 ° C. It heated up over and refluxed at 150 degreeC for 1 hour. Subsequently, after adding 1.7 g of 1-methylimidazole, by-product acetic acid and unreacted acetic anhydride were distilled off, the temperature was raised from 150 ° C to 320 ° C over 2 hours and 50 minutes. The contents were taken out and cooled to room temperature. The resulting solids were pulverized with a particle size of about 0.1 to 1 mm, and then heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, heated up from 250 ° C. to 285 ° C. over 5 hours, and held at 285 ° C. for 3 hours. Solid phase polymerization was performed. It cooled after solid state superposition | polymerization and obtained powdery liquid crystalline polyester. The flow start temperature of this liquid crystalline polyester was 327 degreeC.

Example 1

The liquid crystal polyester obtained in the manufacture example 1 was granulated by the twin screw extruder ("PCM-30" of Ikega Co., Ltd.), it was made into pellet form, and it supplied to a single screw extruder (screw diameter 50mm), It melt | dissolved, it extruded and cooled in the film form from T die (rip length 300mm, lip clearance 1mm, die temperature 350 degreeC), and obtained the liquid-crystal polyester film of 25 micrometers in thickness. The water vapor transmission rate of this liquid crystal polyester film was 0.011 g / m <2> * 24h.

Urethane-based adhesive (Mitsui Takeda Chemical Co., Ltd.): Topic "Takerak A511" / Hardening agent "A50" = 10 on one side of a 250-µm-thick white PET film ("Loiler E20" from Toray Co., Ltd .: titanium oxide) / 1 (mass ratio)) was apply | coated, the liquid crystal polyester film obtained previously was bonded together, and the laminated | multilayer film was obtained. Next, urethane adhesive (homologous) was apply | coated to the liquid-crystal polyester film surface of this laminated | multilayer film, the laminated film of the 50-micrometer-thick LLDPE film and 50-micrometer-thick EVA film was bonded together at the LLDPE surface side, and the back sheet was obtained. As a result of evaluating weather resistance by irradiating xenon from the white PET film side about the obtained back sheet, shape change and tear, such as curvature, were not seen.

Example 2

The same operation as in Example 1 was carried out except that the liquid crystal polyester obtained in Production Example 2 was used instead of the liquid crystal polyester obtained in Production Example 1 to obtain a liquid crystal polyester film having a thickness of 25 µm. The water vapor transmission rate of this liquid crystal polyester film was 0.343 g / m <2> * 24h.

Using the obtained liquid crystal polyester film, the same operation as in Example 1 was carried out to obtain a back sheet. As a result of evaluating weather resistance by irradiating xenon from the white PET film side about the obtained back sheet, shape change and tear, such as curvature, were not seen.

Comparative Example 1

Except not using a white PET film, operation similar to Example 1 was performed and the back seat | sheet was obtained. As a result of evaluating weather resistance by irradiating xenon from the liquid-crystalline polyester film side about the obtained back sheet, tearing was not seen, but big warpage was seen.

Comparative Example 2

Except not using a white PET film, operation similar to Example 2 was performed and the back seat | sheet was obtained. As a result of evaluating weather resistance by irradiating xenon from the liquid-crystalline polyester film side about the obtained back sheet, big warpage was seen and the tear was also seen.

Industrial availability

According to this invention, the solar cell backsheet excellent in weatherability and the solar cell module which use this can be provided.

One … 2 surface protection sheet; Encapsulation layer; 4 solar cell elements; Encapsulation layer, 5... Backsheet, 6. Frame, 51... Polyolefin layer, 52... 53 adhesive layer; Liquid crystal polyester layer, 54. Water vapor barrier layer, 55. 56 adhesive layer; White pigment containing layer.

Claims (9)

As a solar cell back sheet arrange | positioned at the back side of a solar cell element,
The backsheet for solar cells provided with the liquid crystal polyester layer and a white pigment containing layer, and the said white pigment containing layer formed in the back side of the said liquid crystal polyester layer. The method of claim 1,
The liquid crystal polyester layer has a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3), wherein the formulas (1) and (2) And at least one of the repeating units represented by (3) contains a 2,6-naphthylene group, and the content of the repeating unit containing the 2,6-naphthylene group is 40 mol% or more with respect to the total amount of all the repeating units. The solar cell backsheet which is a layer comprised from polyester.
-O-Ar ¹ -CO- (1)
-CO-Ar ² -CO- (2)
-O-Ar ³ -O- (3)
(In the formula, Ar ¹ represents a 2,6-naphthylene group, a 1,4-phenylene group or a 4,4'-biphenylylene group, and Ar ² and Ar ³ each independently represents a 2,6-naphthylene group, 1,4-phenylene group, 1,3-phenylene group, or 4,4'-biphenylylene group, and the 2,6-naphthylene group, the 1,4-phenylene group, the 1,3-phenylene group or The hydrogen atoms in the 4,4'-biphenylylene group may be each independently substituted with a halogen atom, an alkyl group or an aryl group) 3. The method according to claim 1 or 2,
The backsheet for solar cells whose water vapor transmission rate measured at the temperature of 40 degreeC and 90% of a relative humidity of the said liquid crystal polyester layer is 0.1 g / m <2> * 24h or less. The method according to any one of claims 1 to 3,
The white pigment-containing layer is a layer containing at least one white pigment selected from the group consisting of basic lead carbonate, basic lead sulfate, basic lead silicate, zincated, zinc sulfide, lithopone, antimony trioxide and titanium oxide. Backsheet. The method according to any one of claims 1 to 4,
The backsheet for solar cells whose said white pigment containing layer is a layer containing polyester. 6. The method according to any one of claims 1 to 5,
The backsheet for solar cells in which the water vapor barrier layer is formed on at least one surface of the said liquid crystal polyester layer. The method according to claim 6,
The vapor barrier layer is selected from the group of elements selected from the following group (A), the oxide of the element selected from the group (A), the nitride of the element selected from the group (A) and the group (A) The solar cell backsheet which is a layer which consists of at least 1 sort (s) of substance chosen from the group which consists of an oxynitride of an element.
(A) group: aluminum, silicon, titanium, chromium, iron, cobalt, nickel, copper, zinc, silver or gold The method according to any one of claims 1 to 7,
The backsheet for solar cells in which the polyolefin layer is formed in the front side of the said liquid crystal polyester layer. The surface protection sheet is arrange | positioned at the front side of a solar cell element, The solar cell module in which the solar cell backsheet as described in any one of Claims 1-8 is arrange | positioned at the back side of the said solar cell element.

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