JP2010260965A - Sheet - Google Patents

Abstract

【Task】
Provided is a sheet that is easy to adhere to glass, has high light transmittance, flexibility, and water vapor barrier properties, has a low water absorption rate, and is particularly suitable for a sealing material for a solar cell module.
[Solution]
It is a sheet | seat which consists of a resin composition which mix | blended 5-60 mass parts of aromatic monocarboxylic acid ester with respect to 100 mass parts of polyvinyl acetal resin. The aromatic monocarboxylic acid ester is preferably isodecyl benzoate, and the polyvinyl acetal resin used preferably has a degree of polymerization of 400 to 3500 and a degree of acetalization of 70 to 90%. Furthermore, the thickness of the sheet is preferably in the range of 0.1 to 5 mm. The sheet | seat of this invention is used suitably as a sealing material for solar cell modules.
[Selection figure] None

Description

The present invention relates to a sheet used as a sealing material for a solar cell module made of a specific resin composition.

The sealing material for photovoltaic power generation modules protects the photoelectric conversion element and the wiring by directly contacting them. The required properties include adhesion to glass, visible light permeability, flexibility, high water vapor barrier properties, low water absorption, and insulating properties.

As a sealing material for a photovoltaic power generation module, a resin (EVA resin) obtained by copolymerizing vinyl acetate with ethylene as a main component is often used. However, since a simple copolymer of ethylene and vinyl acetate cannot satisfy the required properties, it is generally performed to introduce a crosslink (see Non-Patent Document 1, for example).

In the early stages of development, application of polyvinyl butyral (PVB) resin as a sealing material for a photovoltaic power generation module has been studied (for example, see Patent Document 1).

Since PVB resin has a high glass transition temperature, it needs to be processed at a high temperature in order to seal photoelectric conversion elements and wiring. Moreover, it is glassy and hard at room temperature, and the effect of protecting these photoelectric conversion elements and wirings is poor. In order to solve this problem, it is conceivable to apply a technique of softening the PVB resin with a plasticizer (see, for example, Patent Document 2).

If this technology is applied, it becomes possible to keep the PVB resin sufficiently flexible and protect the photoelectric conversion element and the wiring against mechanical energy such as deformation and impact. However, as exemplified in Patent Document 2, a compound having extremely high hydrophilicity such as triethylene glycol-di-2ethyl butyrate is generally used as the plasticizer for the PVB resin. For this reason, the plasticized PVB resin which mix | blended this becomes a thing with high hygroscopicity and moisture permeability, and the effect which prevents the corrosion of a photoelectric conversion element and wiring is scarce.

JP 2000-91611 A Japanese Patent No. 3101778

Jet Propulsion Laboratory Research Report, Photovoltaic Module Encapsulation. Design and Materials Selection: Volume 1 (1982)

It aims at providing the sheet | seat used as a sealing material for solar cell modules which consists of a specific resin composition.

That is, this invention is a sheet | seat which consists of a resin composition which mix | blended 5-60 mass parts of aromatic monocarboxylic acid ester with respect to 100 mass parts of polyvinyl acetal resins. The aromatic monocarboxylic acid ester is preferably isodecyl benzoate, and the polyvinyl acetal resin used preferably has a degree of polymerization of 400 to 3500 and a degree of acetalization of 70 to 90%. Furthermore, the thickness of the sheet is preferably in the range of 0.1 to 5 mm. The sheet | seat of this invention is used suitably as a sealing material for solar cell modules.

The sheet | seat used as a sealing material for solar cell modules which consists of a specific resin composition is obtained.

Hereinafter, preferred embodiments for carrying out the present invention will be described. The embodiment described below shows an example of the present invention, and the scope of the present invention is not interpreted narrowly.

The aromatic monocarboxylic acid ester is blended in order to reduce the water absorption rate of the sheet and improve the water vapor barrier property. Aromatic monocarboxylic acid ester is a compound that is highly soluble in water and difficult to be dissolved or compatible with water. For this reason, the resin composition obtained by mixing with the polyvinyl acetal resin is difficult to move and diffuse moisture in the composition, and the water absorption of the sheet obtained by molding this resin composition into a sheet shape Can be reduced.
Furthermore, the aromatic monocarboxylic acid ester is particularly compatible with the polyvinyl acetal resin whose composition and degree of polymerization are controlled. For this reason, the obtained sheet is free from fogging due to the poor compatibility and becomes a highly transparent sheet. For example, when such a sheet is used as a sealing material for a solar cell module, a solar cell module having high sunlight transmittance and high power generation efficiency can be obtained.

The aromatic monocarboxylic acid ester preferably has a molecular weight of 150 or more. An aromatic monocarboxylic acid ester having a molecular weight of 150 or more has a high boiling point and a low vapor pressure, and has low volatility. That is, by using a compound in this range, the obtained sheet can maintain a state of high water vapor barrier property and low water absorption even after long-term outdoor exposure. A preferable range of the molecular weight of the aromatic monocarboxylic acid ester is 200 to 1500. If the molecular weight exceeds 1,500, the resin composition sheet may be less flexible. For example, when used as a sealing material for a solar cell module, the solar cell may be damaged during the assembly of the module. There is a high possibility that

The aromatic monocarboxylic acid ester preferably has a melting point of 0 ° C. or lower, a boiling point of 200 ° C. or higher, and a refractive index of 1.4 to 1.6. By setting the melting point to 0 ° C. or less, the flexibility of the resulting sheet is improved, and the hardness, strength, and elongation with respect to the tensile force are optimum values as the sealing material for the solar cell module. Furthermore, by setting the boiling point to 200 ° C. or higher, the volatility is low, the water vapor barrier property is high in outdoor exposure for a long time, and the water absorption rate can be kept small. If the refractive index of the sheet is 1.4 to 1.6, it is almost equal to the refractive index of the glass, so there is little reflection of light at the interface between the glass and the sheet, and the power reaches the solar cell with high efficiency. A highly efficient solar cell module can be obtained.

The blending amount of the aromatic monocarboxylic acid ester is 5 to 60 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin, thereby optimizing the flexibility, hardness, tensile strength and sheet elongation of the obtained sheet. can do. When the amount of the aromatic monocarboxylic acid ester is less than 1 part by mass, the flexibility is insufficient, and there is a possibility that the solar cell is damaged when used as a sealing material for the solar cell module. Moreover, when there are more compounding of aromatic monocarboxylic acid ester than 50 mass parts, a softness | flexibility will become high too much and a sheet | seat may fluidize. In particular, when a sheet is used as a sealing material for a solar cell module in summer or in a high temperature region, solar cells may be displaced due to fluidization of the sheet, which may cause insulation failure. The compounding amount of the aromatic monocarboxylic acid ester is preferably 10 to 50 parts by mass, more preferably 20 to 45 parts by mass. By setting it as this range, when it uses for the sealing material of a solar cell module, for example, it becomes a thing which a solar cell does not break easily and an insulation defect does not occur easily.

Examples of the aromatic monocarboxylic acid ester include methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, benzyl benzoate, hexyl benzoate, octyl benzoate, decyl benzoate, dodecane benzoate, tetradecane benzoate, and the like. There is.

The polyvinyl acetal resin is obtained by acetalizing a polyvinyl alcohol and an aldehyde in the presence of an acidic catalyst.

Polyvinyl alcohol having a saponification degree of 80 mol% or more, preferably 90 mol or more is preferably used. In the present invention, polyvinyl alcohol is preferably used as a 3 to 15% by weight aqueous solution from the viewpoint of handling.

Examples of aldehydes include butyraldehyde, formaldehyde, paraformaldehyde, acetaldehyde, paraacetaldehyde, propionaldehyde, amyl aldehyde, hexyl aldehyde, heptyl aldehyde, 2-ethylhexyl aldehyde, cyclohexyl aldehyde, furfural, glyoxal, glutaraldehyde, benzaldehyde, 2 -Methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like, and one or more aldehydes may be used in combination . Of these, butyraldehyde is preferably used.

What is necessary is just to set the addition amount of an aldehyde suitably according to the acetalization degree of the target polyvinyl acetal. In particular, 40 to 75 parts by mass, preferably 43 to 65 parts by mass with respect to 100 parts by mass of polyvinyl alcohol is preferable because the acetalization reaction is efficiently performed.

Examples of the acid catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid and p-toluenesulfonic acid. What is necessary is just to add a suitable quantity so that the pH of a reaction liquid may be 0.3-2.0 with these acid catalysts.

The degree of polymerization of the polyvinyl acetal resin is 400-3500. If a polyvinyl acetal resin having a degree of polymerization of less than 400 is used, the melt viscosity of the resin composition containing the aromatic monocarboxylic acid ester may be too low. For this reason, when making this resin composition into a sheet | seat by methods, such as extrusion molding, winding of a sheet | seat becomes difficult and also the intensity | strength of a sheet | seat obtained becomes low. When a polyvinyl acetal resin having a degree of polymerization exceeding 3500 is used, the compatibility with the aromatic monocarboxylic acid ester is deteriorated, the resulting sheet may be clouded, and the transparency may be deteriorated. Moreover, since melt viscosity becomes too high at the time of heating, when producing this sheet | seat by methods, such as extrusion molding, extrusion from a die | dye becomes difficult and the sheet | seat obtained becomes a thing with a low flexibility. The degree of polymerization of the polyvinyl acetal resin is preferably 1000 to 3000, and more preferably 1500 to 2400.

The degree of acetalization of the polyvinyl acetal resin is preferably in the range of 70 to 90%. When the degree of acetalization is smaller than this range, the compatibility between the polyvinyl acetal resin and the aromatic monocarboxylic acid ester is deteriorated, the sheet is fogged, and the transparency may be deteriorated. In extreme cases, the aromatic monocarboxylic acid ester may ooze out from the sheet. Furthermore, the controllability of the particle diameter of the polymer particles produced in the synthesis of the polyvinyl acetal resin is poor, and filtration separation and removal of the resin are poor. Even when the degree of acetalization of the polyvinyl acetal resin exceeds 90%, the compatibility between the polyvinyl acetal resin and the ester compound having one or more epoxides in the molecule may be deteriorated, and the transparency of the sheet may be deteriorated. Furthermore, since the reaction rate becomes extremely slow in the synthesis of the polyvinyl acetal resin, a long reaction time and a large amount of catalyst are required, resulting in an increase in production cost. The degree of acetalization of the polyvinyl acetal resin is preferably 75 to 84%, more preferably 78 to 83%.

The thickness of the sheet is preferably in the range of 0.1 to 5 mm. When the thickness is less than 0.1 mm, the strength of the sheet is low, handling properties are deteriorated, and for example, when used as a sealing material for a solar battery module, the effect of preventing damage to the solar battery cell may be reduced. When the thickness exceeds 5 mm, the transparency and light transmittance are deteriorated, so that the power generation efficiency may be reduced in the sealing material of the solar cell module. Furthermore, since the flexibility of a sheet | seat deteriorates, a photovoltaic cell may be damaged. The thickness of the sheet is more preferably 0.3 to 0.9 mm.

The method for producing the sheet may be produced by a known molding method. Specifically, the resin composition may be formed into a sheet by extrusion molding, press molding, blow molding, injection molding, or the like. In particular, a method in which a resin composition and other additives are supplied to an extruder, kneaded and melted, taken out from a die, taken out by a take-up machine, and formed into a sheet is preferable.

By embossing the surfaces of the sheets, the sheets can be prevented from adhering to each other. Moreover, when using as a sealing material for solar cell modules, air can be expelled through the unevenness | corrugation of an embossed pattern, and the bubble remaining in a solar cell module can be prevented. A conventionally known embossing depth and shape may be used.

If necessary, the sheet may be an ultraviolet absorber, an antioxidant, an adhesive strength modifier, a coupling agent, a surfactant, a thermal stabilizer, an infrared absorber, a fluorescent agent, a colorant, a dehydrating agent, an antifoaming agent, One kind or two or more kinds of various additives such as an antistatic agent and a flame retardant may be added. The addition can be carried out by a method of adding a mixture to a polyvinyl acetal resin or a method of adding a mixture to an aromatic monocarboxylic acid ester.

As the ultraviolet absorber, those usually used for plastics can be used, and examples thereof include a benzotriazole ultraviolet absorber, a hindered amine ultraviolet absorber, and a benzoate ultraviolet absorber. Examples of the benzotriazole ultraviolet absorber include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α′dimethylbenzyl) phenyl] -2H-benzo Triazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole. Examples of hindered amine ultraviolet absorbers include 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, and bis (1,2,2). , 6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl malonate, 4- (3- (3,5-di) -T-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) -2,2,6 6-tetramethylpiperidine and the like. Examples of benzoate ultraviolet absorbers include 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate and so on. These ultraviolet absorbers can be used alone or in combination of two or more. The addition amount of a ultraviolet absorber is 10-100,000 ppm on the mass reference | standard with respect to polyvinyl acetal resin, Preferably it is the range of 100-10000 ppm. If it is this range, the light resistance of the obtained polyvinyl acetal sheet can be improved, suppressing manufacturing cost.

Antioxidants include, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among them, phenolic antioxidants are preferable, and alkyl-substituted phenolic antioxidants are particularly preferable.

Examples of phenolic antioxidants include alkyl-substituted phenolic compounds, acrylate compounds, and triazine group-containing phenolic compounds. Examples of the alkyl-substituted phenol compound include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, and octadecyl-3- (3,5-) di- t-butyl-4-hydroxyphenyl) propionate, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), 4,4′-butylidene-bis (4-methyl-6-tert-butylphenol) 4,4′-butylidene-bis (6-tert-butyl-m-cresol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), bis (3-cyclohexyl-2-hydroxy-5) -Methylphenyl) methane, 3,9-bis (2- (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5- Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxy) Phenyl) propionate) methane, triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) and the like. Examples of the acrylate compound include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- ( 1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate. Examples of the triazine group-containing phenol compound include 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy- 3,5-dimethylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3-methyl-5-t-butylanilino) -2,4-bis-octylthio -1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine.

Examples of phosphorus antioxidants include monophosphite compounds and diphosphite compounds. Monophosphite compounds include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2-t-butyl-4 -Methylphenyl) phosphite, tris (cyclohexylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 9,10-dihydro-9-oxa-10-phosphat Phenanthrene-10-oxide, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9 , 10-Dihydro-9-oxa-10-phosphine There is such as phenanthrene. Examples of the diphosphite compound include 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite), 4,4′-isopropylidene-bis (phenyl-di-alkyl ( C12-C15) phosphite), 4,4′-isopropylidene-bis (diphenylmonoalkyl (C12-C15) phosphite), 1,1,3-tris (2-methyl-4-di-tridecyl phosphite) -5-t-butylphenyl) butane, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene phosphite. Of these, monophosphite compounds are preferred.

Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, lauryl stearyl 3,3′-thiodipropionate, pentaerythritol-tetrakis- (Β-lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane.

These antioxidants can be used alone or in combination of two or more. The addition amount of antioxidant is 0.001-5 mass parts with respect to 100 mass parts of polyvinyl acetal resin, Preferably it is the range of 0.01-1 mass part. When it is in this range, it is possible to prevent deterioration of acid value due to thermal deterioration during melt molding and contact with outside air while suppressing manufacturing cost.

Although it does not specifically limit as an adhesive force regulator, For example, the alkali metal salt or alkaline-earth metal salt of organic acid, the alkali metal salt or alkaline-earth metal salt of inorganic acid, modified silicone oil, etc. are mentioned. Examples of the organic acid include carboxylic acids such as octylic acid, hexyl acid, butyric acid, acetic acid, and formic acid. These organic acids may be used alone or in combination of two or more. Examples of inorganic acids include hydrochloric acid and nitric acid. These inorganic acids may be used alone or in combination of two or more.

Examples of the alkali metal salt or alkaline earth metal salt of the organic acid or inorganic acid include the organic acid, potassium salt, inorganic salt, and magnesium salt of the inorganic acid. These alkali metal salts or alkaline earth metal salts of organic acids or inorganic acids may be used alone or in combination of two or more.

Among the alkali metal salts or alkaline earth metal salts of organic acids and inorganic acids, alkali metal salts or alkaline earth metal salts of organic acids having 2 to 16 carbon atoms are preferably used. In particular, a potassium salt or magnesium salt of a carboxylic acid having 2 to 16 carbon atoms is more preferably used. Examples of the alkali metal salt or alkaline earth metal salt of a carboxylic acid having 2 to 16 carbon atoms include potassium acetate, magnesium acetate, potassium propionate, magnesium propionate, potassium 2-ethylbutanoate, 2-ethylbutanoate magnesium, -Potassium ethylhexylate, magnesium 2-ethylhexylate and the like. These potassium salts and magnesium salts of carboxylic acids having 2 to 16 carbon atoms may be used alone or in combination of two or more.

The addition amount of the alkali metal salt or alkaline earth metal salt of the organic acid or inorganic acid is not particularly limited, but is 0.0001 to 1 part by mass, preferably 0 with respect to 100 parts by mass of the polyvinyl acetal resin. 0.001 to 0.5 parts by mass, more preferably 0.01 to 0.2 parts by mass. If it is set as this range, when it uses as a sealing material for solar cell modules, for example, it will become possible to adjust the adhesiveness of a sheet | seat, without impairing light transmittance.

The modified silicone oil is not particularly limited as long as it is obtained by reacting a compound to be modified with polysiloxane. For example, epoxy-modified silicone oil, ether-modified silicone oil, ester-modified silicone oil, amine-modified silicone oil, carboxyl Examples thereof include modified silicone oil. These may be used alone or in combination of two or more.

The molecular weight of these modified silicone oils is not particularly limited, but the molecular weight is 800 to 5000, preferably 1500 to 4000. By setting it as this range, compatibility with polyvinyl acetal resin can be maintained and it can disperse | distribute uniformly in polyvinyl acetal resin. Although the compounding quantity of modified silicone oil is not specifically limited, It is 0.01-0.2 mass part with respect to 100 mass parts of polyvinyl acetal resin, Preferably it is 0.03-0.1 mass part. By setting it as this range, the adhesive force of the sheet can be adjusted while maintaining good compatibility with the polyvinyl acetal resin.

The sheet | seat of this invention is used suitably as a sealing material for solar cell modules. The sheet is easy to adhere to glass, has high light transmittance, flexibility and water vapor barrier properties, and has a low water absorption rate. Since the solar cell module using this as a sealing material for solar cell modules has high light transmittance, the solar cell module is highly efficient in converting sunlight into electric energy and has high flexibility, thus preventing damage to solar cells. In addition, since the water vapor barrier property is high and the water absorption rate is small, the insulation reliability is high. Further, since the sheet has low fluidity at high temperatures, the insulation reliability is high.

Examples of the present invention and comparative examples are shown below using Tables 1 and 2. The present invention is not limited to these examples.

Example 1
A polyvinyl acetal resin having a synthetic saponification degree of 98 mol% and an average polymerization degree of 1700 polyvinyl alcohol 100 g was dissolved in distilled water to obtain a polyvinyl alcohol aqueous solution having a concentration of 10% by weight. While stirring this aqueous solution at 40 ° C. using an anchor type stirring blade, 32 g of 35 wt% hydrochloric acid was added, and then 60 g of butyraldehyde was added dropwise. After confirming that the polyvinyl acetal resin was precipitated in the aqueous solution, the temperature was raised to 50 ° C. while adding 64 g of 35% by weight hydrochloric acid, and the reaction was completed by stirring for 4 hours to obtain a dispersion of the polyvinyl acetal resin. It was. The obtained dispersion was cooled, neutralized with 30% by weight aqueous sodium hydroxide solution to a pH of 7.5, filtered, washed / dried with 20 times the amount of distilled water against the polymer, and the average degree of polymerization. A polyvinyl acetal resin having an acetalization degree of 79.8 wt% was obtained in 1700.

Production of Sheet With respect to 100 parts by mass of polyvinyl acetal resin, the mixture was supplied to a twin screw extruder at a blending ratio of 30 parts by mass of isodecyl benzoate and extruded from a T-die to obtain a polyvinyl acetal sheet having a thickness of 0.6 mm. The sheeting equipment conditions and equipment operating conditions were as follows.
(Sheet equipment)
(1) Extruder: Toshiba Machine Co., Ltd. twin screw extruder, screw φ48mm, raw material supply port, plasticizer supply port, vented (2) Gear pump: Gear pump (capacity 120L / h) installed at the extruder outlet (3) T Die: 1100mm wide
(Equipment operating conditions)
(1) Polyvinyl acetal resin: polyvinyl butyral (average polymerization degree 1700, acetalization degree 79.8%),
(2) Aromatic monocarboxylic acid ester: Isodecyl benzoate (3) Feed rate of resin to the extruder 50 kg / h
(4) Supply rate of isodecyl benzoate 17 kg / h
(5) Degree of devolatilization from the extruder: 300 torr
(6) Barrel set temperature: Polyvinyl acetal resin, isodecyl benzoate supply unit 140 ° C., and after the supply unit, 200 ° C. at the exit of the extruder
(7) Extruder screw rotation speed 150r. p. m.
(8) Q / Ns = (50 + 17) /150=0.45
(9) T die lip clearance 0.95mm
(10) T-die set temperature: 200 ° C
(12) Take-up speed of take-up machine 1.8m / min

Evaluation of sheet (Evaluation of water vapor barrier property of sheet)
The moisture permeability of the sheet at 40 ° C. and 90% relative humidity was measured according to JIS Z 0208 “Moisture permeability test method for moisture-proof packaging material (cup method)”. Normally, the moisture permeability is inversely proportional to the thickness of the sheet. Since thickness may differ in an Example, all the sheets were converted into thickness 1mm and compared.
(Evaluation of sheet water absorption)
Based on JIS K 7209 "Plastics-Determination of water absorption", method A, the saturated water content when immersed in distilled water at 23 ° C was measured.
(Measurement of total light transmittance of sheet)
The total light transmittance was measured according to JIS K 7105 “Testing method for optical properties of plastics”.
(Measurement of sheet haze)
Haze was measured according to JIS K 7105 “Testing method for optical properties of plastics”.
(Measurement of tensile fracture stress and tensile strain of sheet)
The sheet was punched into a dumbbell-shaped test piece 1B of JIS K 7162 “Testing method for plastic-tensile properties Part 2: Molding, extrusion molding and cast plastic test conditions”, and JIS K 7161 “Plastic— The tensile fracture stress and tensile fracture strain were measured at a tensile speed of 50 mm / min according to “Test Method Part 1: General Rules”.
(Measurement of heat shrinkage)
A sheet of 100 mm × 100 mm was heated in a warm bath at 85 ° C. for 1 min, and the rate of change in the length of each side in the width direction and the flow direction of the sheet before and after heating was measured.

Preparation of a simulated solar cell module A sheet of resin composition of the same size is placed on a 10 cm × 20 cm × 3 mm thick glass plate, and a copper wire with a thickness of 0.1 mm is further placed on the center of the short side. So that both sides of the copper wire come out of the glass surface by 2 cm. Further, a copper wire having a thickness of 1 mm and a length of 5 cm was placed perpendicular to the center of the copper wire. On this, a sheet of a resin composition having the same size as the glass plate, 10 cm × 20 cm × 3 mm thick glass plate was sequentially placed, vacuum degassed at 120 ° C. for 15 minutes, and then 130 ° C. with an atmospheric pressure press. X Crimped for 30 minutes.

Evaluation of simulated photovoltaic module (initial sealing performance)
The appearance of the simulated solar cell module after fabrication was observed. The case where the copper wire was not distorted due to the dimensional change of the sheet at the time of crimping was evaluated as ◯.
(Weatherability)
A simulated solar cell module was put into a Dew cycle sunshine weatherometer, an accelerated weathering test was conducted by light irradiation and a rain cycle, and the appearance after 5000 hours was observed. Those that did not change in appearance were marked with ◯.
(Heat-resistant)
The appearance was observed after the simulated solar cell module was left in an atmosphere at 110 ° C. for 2000 hours. Those that did not change in appearance were marked with ◯.
(Flow of sealing material)
The simulated solar cell module was vertically placed in an atmosphere at 100 ° C. and stored for 200 hours, and then the appearance was observed. The case where there was no change in appearance was rated as ◯, and the case where the sealing material flowed out or the glass peeled off was rated as x.
(Temperature cycle)
The simulated solar cell module was set to one cycle of −40 ° C./1 hour and 90 ° C./1 hour (high temperature to low temperature, low temperature to high temperature changed at 65 ° C. per hour), and the simulated solar cell module was allowed to stand during 400 cycles. . The appearance after the end of 400 cycles was observed.
(Moisture resistance)
The simulated solar cell module was left in an atmosphere of 85 ° C./relative humidity 85% RH for 2000 hours, and then the appearance was observed. Those that did not change in appearance were marked with ◯.
(Temperature and humidity cycle)
The simulated solar cell module is kept quiet in a temperature and humidity cycle of -40 ° C / 1 hour, 85 ° C / relative humidity 85% RH / 4 hours (from high temperature and high humidity to low temperature, and from low temperature to high temperature and high humidity at 100 ° C per hour). After 50 cycles, the appearance was observed. Those that did not change in appearance were marked with ◯.

Example 2
A sheet was prepared in the same manner as in Example 1 except that the amount of isodecyl benzoate was 5 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 3
A sheet was prepared in the same manner as in Example 1 except that the amount of isodecyl benzoate was 60 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 4
When synthesizing the polyvinyl acetal resin, a sheet was prepared in the same manner as in Example 1 except that the polymerization degree of the polyvinyl alcohol was set to 400 and the polymerization degree of the polyvinyl acetal resin was set to 400. Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 5
When synthesizing the polyvinyl acetal resin, a sheet was prepared in the same manner as in Example 1 except that the polymerization degree of polyvinyl alcohol was 3300 and the polymerization degree of the polyvinyl acetal resin was 3300. Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 6
When synthesizing the polyvinyl acetal resin, a sheet was produced in the same manner as in Example 1 except that the amount of butyraldehyde added was 53 g, so that the degree of acetalization of the polyvinyl acetal resin was 70.5%. . Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 7
When synthesizing the polyvinyl acetal resin, a sheet was prepared in the same manner as in Example 1 except that the amount of butyraldehyde added was 70 g, so that the degree of acetalization of the polyvinyl acetal resin was 89.0%. . Table 1 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 8
A sheet was produced in the same manner as in Example 1 except that when the sheet was produced, the take-up speed of the take-up machine was 11 m / min, and the thickness was 0.1 mm. Table 2 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Example 9
A sheet was prepared in the same manner as in Example 1 except that the thickness of the sheet of the resin composition was 5.0 mm by setting the take-up speed of the take-up machine to 0.2 m / min when producing the sheet. Table 2 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Comparative Example 1
A sheet was produced in the same manner as in Example 1 except that the amount of isodecyl benzoate was 2 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. Table 2 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Comparative Example 2
A sheet was produced in the same manner as in Example 1 except that the amount of isodecyl benzoate was 70 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. Table 2 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Comparative Example 3
A sheet was produced in the same manner as in Example 1 except that triethylene glycol di-2 ethyl butyrate was used instead of the aromatic monocarboxylic acid ester. Table 2 shows the evaluation results of the sheet and the simulated solar cell module produced using this sheet.

Comparative Example 4
Example 1 except that the sheet was made of EVA (resin copolymerized with vinyl acetate in ethylene, the ratio of ethylene and vinyl acetate is ethylene / vinyl acetate = 70/30, including a crosslinking agent in mass ratio). Simulated solar cell module similar to In addition, EVA sealing material usually crosslinks EVA resin after pressure bonding in the case of modularization. However, since it was not crosslinked under the conditions of the module of Example 1, it was 150 ° C × 20 after atmospheric pressure pressing at 130 ° C for 30 minutes. Heated for minutes to crosslink. Table 2 shows the evaluation results of the sheet and the simulated solar cell module.

As is clear from Tables 1 and 2, in Examples 1 to 9, the moisture permeability and water absorption were low, and the water resistance was good. Moreover, since the total light transmittance is high and the haze is low, it is considered that the light receiving efficiency of the solar battery cell is high and the conversion efficiency into electric energy is high. Furthermore, because of the appropriate tensile fracture stress and tensile fracture strain, there is less risk of damaging solar cells when assembling solar cell modules, etc., and because the heat shrinkage rate is small, solar cells may be destroyed during crimping. It is thought that there is not. In the evaluation of the fabricated simulated solar cell module, each item passed.

In Comparative Examples 1 and 3, the water absorption rate was large, and in the water resistance and temperature / humidity cycle evaluation of the simulated solar cell module, a phenomenon was observed in which moisture entered between the glass and the sheet at the end and the sheet became cloudy.

In Comparative Example 2, the thermal characteristics were inferior, and generation of bubbles was observed between the glass and the sheet in the weather resistance, heat resistance, and temperature cycle evaluation of the simulated solar cell module. Moreover, in the flow evaluation of the sealing material, a phenomenon that the sealing material exudes slightly from the glass surface was also observed.

In Comparative Example 4, the heat shrinkage ratio was large, and a phenomenon in which the copper wire was shifted was observed in the evaluation of the initial sealing performance of the simulated solar cell module. Further, in the water resistance and temperature / humidity cycle evaluation, it was observed that water entered between the glass and the sheet at the end and the water was raised.

The sheet of the resin composition of the present invention is easily bonded to glass, has low light transmittance, flexibility, water absorption, and high water vapor barrier properties. In particular, it is suitably used in a sealing material for solar cell modules that converts solar energy into electrical energy.
Moreover, since the sheet | seat of this invention has transparency, intensity | strength, and a softness | flexibility, it can utilize for a laminated glass. In particular, since the water absorption is small, a laminated glass having a shape in which the edge portion is exposed outdoors can be obtained. Moreover, it can utilize for construction and industrial materials, such as a transparent adhesive tape and the base material of an adhesive tape.

Claims (6)

The sheet | seat which consists of a resin composition which mix | blended 5-60 mass parts of aromatic monocarboxylic acid ester with respect to 100 mass parts of polyvinyl acetal resin. The sheet according to claim 1, wherein the aromatic monocarboxylic acid ester is isodecyl benzoate. The degree of polymerization of polyvinyl acetal resin is 400-3500, The sheet according to claim 1 or 2 characterized by things. The acetalization degree of polyvinyl acetal resin is 70 to 90%, The sheet | seat as described in any one of Claims 1-3 characterized by the above-mentioned. The sheet according to any one of claims 1 to 4, wherein the sheet has a thickness of 0.1 to 5 mm. The sheet according to any one of claims 1 to 5, which is used as a sealing material for a solar cell module.