WAVELENGTH CONVERSION MATERIAL AND SOLAR CELL SEALING FILM CONTAINING THE SAME

Abstract

Provided is a wavelength conversion material composed of resin particles comprising an acrylic resin and an organic rare earth complex contained in the acrylic resin, in which the acrylic resin is obtained from an acrylic resin composition comprising a cross-linking agent, and deterioration of the organic rare earth complex is prevented. A wavelength conversion material composed of resin particles comprising an acrylic resin and an organic rare earth complex contained in the acrylic resin, wherein the acrylic resin is a polymer which is a reaction product of an acrylic resin composition comprising a (meth)acrylate monomer, a crosslinking agent and an azo polymerization initiator, wherein the crosslinking agent is a compound represented by the following formula (I):

##STR00001##

where R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a methyl group and n represents an integer of 2 to 14, and the content of the cross-linking agent is: 0.1 to 5 parts by mass based on 100 parts by mass of the (meth)acrylate monomer when n in formula (I) is 2; or 0.1 to 50 parts by mass based on 100 parts by mass of the (meth)acrylate monomer when n in formula (I) is 3 to 14.

Claims

1. A wavelength conversion material composed of resin particles comprising an acrylic resin and an organic rare earth complex contained in the acrylic resin, wherein the acrylic resin is a polymer which is a reaction product of an acrylic resin composition comprising a (meth)acrylate monomer, a crosslinking agent and an azo polymerization initiator, wherein the crosslinking agent is a compound represented by the following formula (I): ##STR00006## where R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a methyl group and n represents an integer of 2 to 14, and the content of the cross-linking agent is: 0.1 to 5 parts by mass based on 100 parts by mass of the (meth)acrylate monomer when n in formula (I) is 2; or 0.1 to 50 parts by mass based on 100 parts by mass of the (meth)acrylate monomer when n in formula (I) is 3 to 14.

2. The wavelength conversion material according to claim 1, wherein the cross-linking agent is a compound represented by formula (I) where R.sup.1 and R.sup.2 are methyl groups and n is 2.

3. The wavelength conversion material according to claim 1, wherein the cross-linking agent is a compound represented by formula (I) where R.sup.1 and R.sup.2 are methyl groups and n is 9.

4. The wavelength conversion material according to claim 1, wherein the (meth)acrylate monomer is methyl methacrylate.

5. The wavelength conversion material according to claim 1, wherein the organic rare earth complex is a europium complex represented by the following formula (II): ##STR00007## where R's each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms that may be optionally substituted; and n represents an integer of 1 to 4.

6. The wavelength conversion material according to claim 5, wherein the organic rare earth complex is a europium complex represented by formula (II) where R's all represent hydrogen atoms and n is 1.

7. A solar cell sealing film comprising a resin material comprising an olefin (co)polymer and the wavelength conversion material according to claim 1.

8. The solar cell sealing film according to claim 7, wherein the olefin (co)polymer is one or more polymers selected from the group consisting of metallocene catalyzed ethylene--olefin copolymers (m-LLDPE), low density polyethylenes (LDPE), linear low density polyethylenes (LLDPE), polypropylenes, poly butenes and etylene-polar monomer copolymers.

9. A solar cell module formed by sealing a solar cell with the solar cell sealing film according to claim 8.

Description

EXAMPLES

[0103] The present invention will be more specifically described by way of the following Examples.

[0104] [Evaluation of Wavelength Conversion Materials] [0105] (1) Preparation of wavelength conversion materials (resin particles containing an organic rare earth complex)

[0106] Suspension polymerization using the materials shown in Table 1 was carried out by a customary method to obtain spherical resin particles (average particle size: 100 m). [0107] (2) Hygrothermal Deterioration Test

[0108] The wavelength conversion materials obtained as above were each placed in an ampoule bottle. Fluorescence intensity was measured by spectrophotometer (F-7000, manufactured by Hitachi High-Technologies Corporation) with the bottle opened. Measurement conditions are: photomultiplier voltage: 400 V, excitation-side slit: 20 nm, fluorescence-side slit: 10 nm and scan speed: 240 nm/min. Irradiation wavelength was set at 325 nm. The wavelength was plotted on the X axis and the amount of luminescence on the Y axis. The area of the region surrounded by the curve of the resultant function f(x) from the initiation wavelength of a luminescence peak to the termination wavelength thereof and the linear line connecting two points (X=X0 and X1) on the function f (x) was calculated and defined as a fluorescence intensity. Then, the bottles were allowed to stand still in the environment at 85 C. and 85% RH for 250 hours and the fluorescence intensity was again measured to computationally obtain the residual ratio of fluorescence intensity (from the initial state).

[0109] [Evaluation of Solar Cell Sealing Films] [0110] (1) Preparation of Solar Cell Sealing Films

[0111] Materials were supplied to a roll mill in accordance with the formulation shown in Table 2 and kneaded at 70 C. to prepare a solar cell sealing film composition. The solar cell sealing film composition was subjected to calendering at 70 C. and allowed to cool to prepare a solar cell sealing film (thickness: 0.46 mm). In Table 2, wavelength conversion materials A to M represent the wavelength conversion materials manufactured in Examples A to H and Comparative Examples I to M shown in Table 1. [0112] (2) Preparation of Cured Samples by Crosslinking

[0113] The solar cell sealing film obtained as above was sandwiched by two transparent glass plates (thickness 3.2 mm). The obtained stack was degassed for 2 minutes and pressurized for 8 minutes by a vacuum laminator at 90 C. to be laminated to give a laminate. Then the laminate was heated in an oven at 155 C. for 30 minutes to cure by crosslinking to prepare a sample. [0114] (3) Evaluation Methods [0115] (i) Light Transmittance (%)

[0116] The above sample was subjected to spectral measurement at 400 to 1000 nm by a spectrophotometer (U-4100, manufactured by Hitachi, Ltd.). The average value thereof was determined as a light transmittance (%). [0117] (ii) Hygrothermal Deterioration Test

[0118] The above sample was measured by a spectrophotometer (F-7000, manufactured by Hitachi High-Technologies Corporation) to obtain a fluorescence intensity. Measurement conditions are: photomultiplier voltage: 400 V, excitation-side slit: 20 nm, fluorescence-side slit: 10 nm and scan speed: 240 nm/min. Irradiation wavelength was set at 325 nm. The wavelength was plotted on the X axis and the amount of luminescence on the Y axis. The area of the region surrounded by the curve of the resultant function f(x) from the initiation wavelength of a luminescence peak to the termination wavelength thereof and the linear line connecting two points X=X0 and X1 on the function f(x) was calculated and defined as a fluorescence intensity. Then, the bottles were allowed to stand still in the environment at 85 C. and 85% RH for 250 hours and the fluorescence intensity was again measured to computationally obtain the residual ratio of fluorescence intensity (from the initial state). [0119] (4) Evaluation Results

[0120] The evaluation results are shown in Tables.

TABLE-US-00001 TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Resin particle ple A ple B ple C ple D ple E ple F ple G Formulation Monomer Methyl methacrylate 100 100 100 100 100 100 100 (parts by weight), Polymerization Azo polymerization initiator*.sup.1 0.25 0.25 0.25 0.25 0.25 0.25 0.25 (organic rare initiator Organic peroxide (1)*.sup.2 0.125 0.125 0.125 0.125 0.125 0.125 0.125 earth complex Crosslinking Crosslinking agent (1)*.sup.3 1 2.5 5 is indicated by agent Crosslinking agent (2)*.sup.4 1 5 10 25 weight %) Crosslinking agent (3)*.sup.5 Organic rare earth complex*.sup.6 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Hygrothermal deterioration-test evaluation result, 42 32 30 30 40 50 47 residual ratio (%) Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam- Resin particle ple H ple I ple J ple K ple L ple M Formulation Monomer Methyl methacrylate 100 100 100 100 100 100 (parts by weight), Polymerization Azo polymerization initiator*.sup.1 0.25 0.25 0.25 0.25 0.25 0.25 (organic rare initiator Organic peroxide (1)*.sup.2 0.125 0.125 0.125 0.125 0.125 0.125 earth complex Crosslinking Crosslinking agent (1)*.sup.3 8 10 45 is indicated by agent Crosslinking agent (2)*.sup.4 45 100 weight %) Crosslinking agent (3)*.sup.5 10 Organic rare earth complex*.sup.6 0.1 0.1 0.1 0.1 0.1 0.1 Hygrothermal deterioration-test evaluation result, 55 18 5 3 25 15 residual ratio (%) Note: *.sup.12,2-Azobis(isobutyronitrile) (AIBN) *.sup.2Benzoyl peroxide (Nyper BW (manufactured by NOF CORPORATION)) *.sup.3Ethylene glycol dimethacrylate (Light Ester EG (manufactured by KYOEISHA CHEMICAL Co., Ltd.)) *.sup.41,9-Nonane diol dimethacrylate (Light Ester 1,9ND (manufactured by KYOEISHA CHEMICAL Co., Ltd.)) *.sup.5Nonane ethylene glycol dimethacrylate (Light Ester 9EG (manufactured by KYOEISHA CHEMICAL Co., Ltd.)) *.sup.6Eu(hfa).sub.3(TPPO).sub.2 (Lumisis E-300 (manufactured by Central Techno Co.,)

TABLE-US-00002 TABLE 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Formulation Olefin (co)polymer (1)*.sup.7 100 100 100 100 100 100 100 (parts by Organic peroxide*.sup.8 0.35 0.35 0.35 0.35 0.35 0.35 0.35 weight) Crosslinking agent*.sup.9 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Silane coupling agent*.sup.10 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Wavelength conversion material A B C D E F G (resin particle) Resin-particle content 0.3 0.3 0.3 0.3 0.3 0.3 0.3 (as organic rare earth complex) 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 Evaluation Light beam transmittance (%) 91.0 90.9 91.0 90.8 90.8 90.9 91.0 results Hygrothermal deterioration-test 48.0 40.6 35.2 38.9 46.3 54.6 60.3 evaluation result (residual ratio (%)) Comparative Comparative Comparative Comparative Comparative Example 8 Example 1 Example 2 Example 3 Example 4 Example 5 Formulation Olefin (co)polymer (1)*.sup.7 100 100 100 100 100 100 (parts by Organic peroxide*.sup.8 0.35 0.35 0.35 0.35 0.35 0.35 weight) Crosslinking agent*.sup.9 0.5 0.5 0.5 0.5 0.5 0.5 Silane coupling agent*.sup.10 0.3 0.3 0.3 0.3 0.3 0.3 Wavelength conversion material H I J K L M (resin particle) Resin-particle content 0.3 0.3 0.3 0.3 0.3 0.3 (as organic rare earth complex) 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 Evaluation Light beam transmittance (%) 90.9 90.8 90.8 90.9 91.0 90.9 results Hygrothermal deterioration-test 50.6 15.5 10.6 5.8 30.5 15.5 evaluation result (residual ratio (%)) Note: *.sup.7EVA: Content of vinyl acetate content: 26 weight % (Ultracene 634, manufactured by Tosoh Corporation) *.sup.8t-Butylperoxy-2-ethylhexyl monocarbonate (Perbutyl E, manufactured by NOF corporation) *.sup.9Triallyl isocyanurate (TAIC, manufactured by Nippon Kasei Chemical CO., Ltd.) *.sup.10-Methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0121] As shown in the Tables, it was demonstrated in the hygrothermal deterioration test that the fluorescence intensity of the wavelength conversion material does not readily decrease. The wavelength conversion material is composed of resin (fine) particles comprising an acrylic resin, which contains an organic rare earth complex and which is a polymer obtained by a reaction of a composition comprising methyl methacrylate as a (meth)acrylate monomer and ethylene glycol dimethacrylate, or 1,9-nonanediol dimethacrylate as a cross-linking agent in predetermined amounts and comprising an azo polymerization initiator as a polymerization initiator. Accordingly, it was demonstrated that the wavelength conversion material of the present invention maintains the wavelength conversion effect for a long term, and that the solar cell sealing film of the present invention is capable of maintaining the effect of improving power generation efficiency for a long term.

[0122] The present invention is not limited by the embodiments and Examples mentioned above and can be variously modified within the gist of the invention.

INDUSTRIAL APPLICABILITY

[0123] According to the present invention, it is possible to provide a solar cell module that is improved in power generation efficiency of a solar cell due to the use of wavelength conversion material and is capable of maintaining high power generation efficiency for a long term.

REFERENCE SIGNS LIST

[0124] 11 Front-side transparent protecting member [0125] 12 Backside protecting member [0126] 13A Front-side sealing film [0127] 13B Backside sealing film [0128] 14 Solar cells