JP2012079996A - Method of manufacturing sealing sheet for solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a sealing sheet for a solar cell formed by being impregnated with organic peroxide, ultraviolet absorber, and light stabilizer.SOLUTION: In the method of manufacturing a sealing sheet for a solar cell, a mixed solution is manufactured by dissolving solid ultraviolet absorber and solid light stabilizer into liquid organic peroxide at 30 to 45°C. Then by supplying ethylene copolymer pellets and the mixed solution into a rotary container, and by rotating the rotary container while heating the ethylene copolymer pellets, the ethylene copolymer pellets are impregnated with the mixed solution in a liquid state to manufacture mixed solution containing pellets. And the mixed solution containing pellets are supplied to an extruder to be fused and kneaded, and then extruded from the extruder, thereby manufacturing the sealing sheet for a solar cell.

Description

  The present invention relates to a method for producing a solar cell encapsulating sheet.

  In recent years, depletion of fossil fuels such as crude oil and environmental destruction such as global warming caused by the use of fossil fuels have become global problems. As clean energy alternative to fossil fuels, various energy such as tidal current, ocean current, ocean energy such as waves, solar power generation, wind power generation, hydroelectric power generation, biomass, geothermal heat, temperature difference are being studied.

  Solar power generation is particularly attracting attention as clean energy, and solar cells are being developed. The solar cell module seals the solar cell from the front and back with a solar cell encapsulating sheet, and the front side solar cell encapsulating sheet has a surface side transparent protective member such as a glass plate on the back side solar cell encapsulating sheet. The back side protection member (back sheet) is laminated and integrated.

  As the solar cell encapsulating sheet, Patent Document 1 discloses a protective sheet for a solar cell module made of an ethylene copolymer containing an organic peroxide, as an organic peroxide, a dialkyl peroxide (A), A blend of at least one peroxide (B) selected from the group consisting of alkyl peroxyesters and peroxyketals at a ratio (A) / (B) of 10/90 to 90/10. A protective sheet for a solar cell module using the above is disclosed.

  Here, when the additive is mixed in the synthetic resin, the additive is not uniformly mixed in the synthetic resin, simply by supplying the synthetic resin and the additive to the extruder and melt-kneading. Then, a masterbatch containing the additive in a high concentration in the synthetic resin is prepared, and the masterbatch is supplied to the extruder together with the synthetic resin and melt-kneaded to uniformly mix the additive in the synthetic resin. Things have been done.

  And the protective sheet for solar cell modules of patent document 1 is manufactured by T-die method in Example 1, supplying an ethylene-vinyl acetate copolymer, an organic peroxide, and another additive to an extruder. Although not clearly described, in Example 1, a masterbatch containing an organic peroxide and other additives at a high concentration was prepared in advance, and the masterbatch of this additive and ethylene- It is considered that a protective sheet for a solar cell module is manufactured by a T-die method by supplying a vinyl acetate copolymer to an extruder.

  The additive master batch is manufactured by supplying an organic peroxide, other additives such as an ultraviolet absorber and a light stabilizer to the extruder together with a synthetic resin, and melt-kneading them. Therefore, in producing a protective sheet for a solar cell module, the organic peroxide is supplied to the extruder twice and melt-kneaded, and the frictional heat accompanying the heating and kneading in the extruder several times. It is easy to disassemble.

  Therefore, when manufacturing a protective sheet for a solar cell module by the T-die method, the organic peroxide is decomposed in an extruder or T-die to crosslink the ethylene-vinyl acetate copolymer, and the resulting protection for the solar cell module There is a problem that the thickness of the sheet is not uniform, or gel is generated in the form of spots on the surface of the solar cell module protective sheet, that is, so-called fish eyes are generated and the surface property is lowered.

  Thus, Patent Document 2 discloses a method for producing a crosslinkable sheet in which an organic peroxide is brought into contact with the surface of an ethylene-based copolymer sheet in a liquid state and the organic peroxide is permeated into the sheet.

  However, the above-mentioned method for producing a crosslinkable sheet has a problem that the ethylene-based copolymer sheet is not sufficiently impregnated with an organic peroxide and is not uniformly crosslinked when the crosslinkable sheet is crosslinked. is doing.

  Further, in the above method for producing a crosslinkable sheet, a solid additive such as an ultraviolet absorber or a light stabilizer can be adhered to the surface of the crosslinkable sheet, but can be contained in the crosslinkable sheet. Have difficulty. If the solid additive is simply adhered to the surface of the crosslinkable sheet, the solid additive may fall off the surface of the crosslinkable sheet during the manufacturing process of the solar cell module. A necessary amount of additives cannot be contained, and there arises a problem that the durability is insufficient for use as a solar cell encapsulating sheet used for a long period of time.

JP 11-26791 A JP 59-138234 A

  The present invention provides a method for producing a solar cell encapsulating sheet which contains a desired amount of an organic peroxide, an ultraviolet absorber and a light stabilizer and can be uniformly crosslinked and has no fish eye.

  The manufacturing method of the solar cell encapsulating sheet of the present invention is to produce a mixed solution by dissolving a solid ultraviolet absorber and a solid light stabilizer at 30 to 45 ° C. in a liquid organic peroxide, Supplying the ethylene copolymer pellets and the mixed solution into a rotating container and rotating the rotating container while heating the ethylene copolymer pellets, the mixed solution in the ethylene copolymer pellets The mixture solution is impregnated in a liquid form to produce a mixed solution-containing pellet, the mixed solution-containing pellet is supplied to an extruder, melt-kneaded, and extruded from the extruder to produce a solar cell sealing sheet. .

  The ethylene copolymer constituting the ethylene copolymer pellet is not particularly limited, and is, for example, a copolymer of ethylene and a copolymerizable monomer copolymerizable with ethylene. As the copolymerizable monomer, vinyl acetate, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, maleic acid, maleic anhydride, maleic acid are used from the viewpoint of adhesion and transparency of the resulting solar cell encapsulating sheet. An acid ester is mentioned, and vinyl acetate is preferable. The copolymerizable monomer may be copolymerized with ethylene alone, or two or more copolymerizable monomers may be copolymerized with ethylene.

  If the content of the copolymerizable monomer contained in the ethylene copolymer is small, the power generation performance of the solar cell module may be reduced due to a decrease in the transparency of the solar cell sealing sheet. Since the film formability of the solar cell encapsulating sheet may deteriorate, 5 to 50% by weight is preferable.

  The method for producing the ethylene copolymer pellets is not particularly limited. For example, the ethylene copolymer is supplied to an extruder, melted and kneaded, and extruded from the extruder into a strand (bar shape) or a sheet. Alternatively, a method of producing an ethylene copolymer pellet by cutting a sheet-like molded body into a pellet shape using a pelletizer, and the like can be mentioned.

  The ethylene-based copolymer pellets are impregnated with a mixed solution as described later. This mixed solution is produced by dissolving a solid ultraviolet absorber and a solid light stabilizer in a liquid organic peroxide. The

  The organic peroxide used in the present invention only needs to be liquid under the conditions for dissolving the ultraviolet absorber and the light stabilizer and for impregnating the mixed solution into the ethylene copolymer pellets in the rotating container.

  Examples of such an organic peroxide include 1,1-di (t-butylperoxy) cyclohexane (111 ° C.), 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl. ) Propane (114 ° C), t-hexyl peroxyisopropyl monocarbonate (115 ° C), t-butyl peroxylaurate (118 ° C), t-butyl peroxyisopropyl monocarbonate (118 ° C), t-butyl peroxy Maleic acid (119 ° C.), t-butyl peroxy-3,5,5-trimethylhexanoate (119 ° C.), t-butyl peroxy 2-ethylhexyl monocarbonate (119 ° C.), t-hexyl peroxybenzoate ( 119 ° C.), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane (119 ° C.), t Butyl peroxyacetate (121 ° C), 2,2-di (t-butylperoxy) butane (122 ° C), t-butylperoxybenzoate (125 ° C), n-butyl 4,4-di- (t- Butylperoxy) valerate (127 ° C), dicumyl peroxide (136 ° C), di-t-hexyl peroxide (136 ° C), t-butylcumyl peroxide (137 ° C), di (2-t-butylperoxide) Oxyisopropyl) benzene (138 ° C.), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (138 ° C.) and the like. Also good. The temperature in parentheses is the one-hour half-life temperature of the organic peroxide.

  If the one-hour half-life temperature of the organic peroxide is low, the ethylene-based copolymer pellets are decomposed in the rotating container. Therefore, the temperature is preferably 100 ° C. or higher. Since the productivity may be lowered, for example, it is necessary to increase the temperature, the temperature is more preferably 100 to 160 ° C, and particularly preferably 100 to 140 ° C.

  The ultraviolet absorber may be a solid, preferably a powder, and soluble in the organic peroxide at 30 to 45 ° C. under the condition of being dissolved in the organic peroxide. In addition, it is necessary for an ultraviolet absorber to maintain the state melt | dissolved in the organic peroxide, without solidifying and vaporizing on the conditions which impregnate an ethylene-type copolymer pellet with a mixed solution in a rotary container.

  Examples of such ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone. In addition, an ultraviolet absorber may be used independently or 2 or more types may be used together.

  If the amount of the UV absorber dissolved in the organic peroxide is small, the effect of the UV absorber may not be obtained, and if it is large, the UV absorber cannot be completely dissolved in the organic peroxide. Therefore, the amount is preferably 10 to 1000 parts by weight, more preferably 100 to 500 parts by weight with respect to 100 parts by weight of the organic peroxide.

  The light stabilizer only needs to be solid, preferably powdery, and soluble in the organic peroxide at 30 to 45 ° C. under the condition of being dissolved in the organic peroxide. In addition, it is necessary for the light stabilizer not to be solidified and vaporized under the condition that the ethylene copolymer pellets are impregnated with the mixed solution in the rotating container, and to maintain a state dissolved in the organic peroxide.

  As such a light stabilizer, a hindered amine light stabilizer is preferable. Examples of the hindered amine light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2, succinate. 6,6-tetramethylpiperidine polycondensate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, poly {[6-[(1 , 1,3,3-tetramethylbutyl) amino] -1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [ (2,2,6,6-tetramethyl-4-piperidyl) imino]} and the like. These may be used alone or in combination of two or more.

  If the amount of the light stabilizer dissolved in the organic peroxide is small, the effect of the light stabilizer may not be obtained. If the amount is large, the light stabilizer cannot be completely dissolved in the organic peroxide. Therefore, the amount is preferably 10 to 1000 parts by weight, more preferably 100 to 500 parts by weight with respect to 100 parts by weight of the organic peroxide.

  The mixed solution is produced by dissolving an ultraviolet absorber and a light stabilizer at 30 to 45 ° C. in an organic peroxide. In addition, when dissolving a ultraviolet absorber and a light stabilizer in an organic peroxide, it is preferable to carry out under normal pressure without performing pressurization and pressure reduction. As described above, when the solid ultraviolet absorber and the light stabilizer are dissolved in a liquid organic peroxide to prepare a mixed solution, the ethylene-based copolymer pellets are impregnated with the mixed solution in the manner described later. Furthermore, a mixed solution-containing pellet obtained by sufficiently impregnating an ethylene copolymer pellet with an organic peroxide together with an ultraviolet absorber and a light stabilizer can be produced.

  And by manufacturing the solar cell sealing sheet by extrusion molding using the mixed solution-containing pellet, the organic peroxide, the ultraviolet absorber and the light stabilizer are contained substantially uniformly as a whole. A sealing sheet can be manufactured.

  Furthermore, since the ultraviolet absorber and the light stabilizer are impregnated inside the mixed solution-containing pellet, the mixed solution is used during the process of manufacturing the solar cell sealing sheet using the mixed solution-containing pellet. The ultraviolet absorbers and light stabilizers contained in the contained pellets do not fall off, and by using the mixed solution-containing pellets, a desired amount of ultraviolet absorbers and light stabilizers can be accurately added to the solar cell sealing sheet. The sealing sheet for solar cells which can be contained and was excellent in durability can be manufactured.

  The procedure for dissolving the ultraviolet absorber and the light stabilizer in the organic peroxide is not particularly limited. For example, the organic peroxide, the ultraviolet absorber and the light stabilizer are supplied to a known stirring device and the organic peroxide is dissolved. What is necessary is just to melt | dissolve a ultraviolet absorber and a light stabilizer in an organic peroxide by heating so that a thing may become 30-45 degreeC.

  If the temperature at which the UV absorber and the light stabilizer are dissolved in the organic peroxide is low, the UV absorber or the light stabilizer may not be dissolved in the organic peroxide. Therefore, the organic peroxide is adjusted to 30 to 45 ° C.

  Although it does not specifically limit as said stirring apparatus, The stirring apparatus provided with the stirring blade is preferable. Examples of the stirring blade include a turbine blade, a propeller blade, a paddle blade, a turbine blade, a spool blade, a horseshoe blade, and a ribbon blade, and a turbine blade is preferable.

  The mixed solution is supplied into the rotating container together with the ethylene copolymer pellets, but if the total amount of the mixed solution supplied into the rotating container is small, the crosslinkability of the resulting solar cell encapsulating sheet decreases, The solar cell encapsulating sheet may not be sufficiently crosslinked, and in many cases, excess organic peroxide may bleed out on the surface of the solar cell encapsulating sheet. 0.3-70 weight part is preferable with respect to 100 weight part of total amount of the ethylene-type copolymer pellet made, and 5-60 weight part is more preferable.

  Next, the ethylene copolymer pellets and the mixed solution are supplied into the rotating container. As this rotary container, it is only necessary to mix the ethylene copolymer pellets and the mixed solution so that the ethylene copolymer pellets can be impregnated with the mixed solution. Examples of the apparatus equipped with such a rotating container include a tumbler mixer and a rotary mixer, and a tumbler mixer is preferable.

  Then, the rotating vessel is rotated, the ethylene copolymer pellets and the mixed solution are stirred and brought into contact in the rotating vessel, and the mixed solution is impregnated into the ethylene copolymer pellets to produce mixed solution-containing pellets. . In addition, it is preferable to supply the ethylene copolymer pellets in the entire amount of the ethylene copolymer pellets before rotating the rotating container. On the other hand, the total amount of the mixed solution may be supplied into the rotating container before the rotating container is rotated, or may be divided and supplied, but the ethylene copolymer pellets can be uniformly impregnated. Therefore, it is preferable to divide and supply in the rotating container.

  When the temperature of the ethylene copolymer pellets when impregnating the mixed solution into the ethylene copolymer pellets is low, it takes a long time to impregnate the mixed solution into the ethylene copolymer pellets. The ethylene copolymer pellets are fused to each other, or the ethylene copolymer pellets are fused to the inner surface of the rotary container, so that the mixed solution cannot be uniformly impregnated into the ethylene copolymer pellets. ° C is preferred, and 30 to 40 ° C is more preferred. The temperature of the ethylene copolymer pellets refers to the surface temperature of the ethylene copolymer pellets. Even when the ethylene-based copolymer pellet is impregnated with the mixed solution, it is preferably carried out under normal pressure without applying pressure and reduced pressure.

  Also, if the time for impregnating the ethylene copolymer pellets with the mixed solution is short, the mixed solution may not be sufficiently impregnated into the ethylene copolymer pellets. Since there is no change in the effect of impregnating the copolymer pellet with the mixed solution, 2 to 7 hours are preferable, and 3 to 5 hours are more preferable.

  In addition to the ethylene copolymer and organic peroxide, additives such as a crosslinking aid and a coupling agent are supplied to the rotating container within a range that does not impair the physical properties of the solar cell sealing sheet. May be.

  The crosslinking aid is not particularly limited, and examples thereof include polyfunctional monomers having two or more allyl groups, vinyl groups, acryloyl groups or methacryloyl groups. Examples of such polyfunctional monomers include diallyl phthalate. , Diallyl itaconate, diallyl maleate, triallyl isocyanurate, triallyl cyanurate, triallyl phosphate, divinylbenzene; 1,6-hexanediol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, (Meth) acrylates such as trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ε-caprolactone modified dipentaerythritol, al Le-modified dipentaerythritol (meth) acrylate. It may be used alone, or two or more may be used in combination.

  If the total amount of the crosslinking aid supplied to the rotating container is small, crosslinking of the solar cell encapsulating sheet may be insufficient. Since crosslinking may proceed in the inside to produce a gel or only a sealing sheet for solar cells with a non-uniform thickness may be obtained, the total amount of ethylene copolymer pellets fed into the rotating container is 100 parts by weight. The amount is preferably 0.01 to 20 parts by weight.

  The coupling agent is not particularly limited, and for example, a silane coupling agent having one or more functional groups selected from the group consisting of an amino group, a glycidyl group, a methacryloxy group, and a mercapto group is preferably used. Examples thereof include 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. More than one species may be used in combination.

  If the total amount of the coupling agent supplied to the rotating container is small, the effect of the coupling agent is difficult to obtain, and if it is large, the ethylene-based copolymer pellets may remain without being impregnated. 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight of the total amount of the ethylene-based copolymer pellets to be supplied.

  As described above, when impregnating the ethylene copolymer pellets with the mixed solution, the rotating vessel is rotated by supplying the ethylene copolymer pellets and the mixed solution and, if necessary, additives into the rotating vessel. Therefore, ethylene copolymer pellets and mixed solutions do not receive frictional heat between the stirring blades as in the case of using a stirring device having stirring blades, without decomposing the organic peroxide, The ethylene-based copolymer pellet is reliably impregnated with an organic peroxide. At this time, since the ultraviolet absorber and the light stabilizer are dissolved in the organic peroxide, the ultraviolet absorber and the light stabilizer are also impregnated into the ethylene copolymer pellet together with the organic peroxide. The copolymer pellets are reliably impregnated with an organic peroxide and an ultraviolet absorber and light stabilizer.

  When an additive other than the mixed solution is supplied into the rotating container, and the additive is in a liquid state under the condition that the ethylene copolymer pellet is impregnated with the mixed solution in the rotating container, the ethylene-based copolymer is used. The polymer pellet is also impregnated with the additive together with the mixed solution. In addition, when the additive is solid under the condition that the ethylene-based copolymer pellet is impregnated with the mixed solution in the rotating vessel, the mixed solution adheres to the ethylene-based copolymer pellet, and thus the ethylene-based pellet Adhesiveness develops on the surface of the copolymer pellet, and the solid additive adheres uniformly and reliably to the surface of the ethylene copolymer pellet due to this adhesiveness.

  Next, a mixed solution-containing pellet and an ethylene copolymer pellet that does not contain an organic peroxide different from the pellet are supplied to an extruder and, if necessary, the one-hour half-life of the organic peroxide. A solar cell encapsulating sheet can be obtained by melt-kneading at a temperature lower than the temperature and extruding from a die such as a T die attached to the tip of the extruder. In addition, what is necessary is just to melt-knead at the temperature lower than the one-hour half-life temperature of the lowest organic peroxide, when 2 or more types of organic peroxides are contained. In addition, you may supply only a mixed solution containing pellet to an extruder.

  Thus, in the present invention, since the organic peroxide passes through the extruder only once, the organic peroxide can be decomposed by heating in the extruder or by frictional heat with the screw blade as much as possible. Therefore, the organic peroxide is unexpectedly decomposed in the extruder or die, and the thickness of the resulting solar cell encapsulating sheet becomes non-uniform, or fish eyes are formed on the surface of the solar cell encapsulating sheet. There will be no problems.

  Furthermore, since the desired amount of UV absorber and light stabilizer are contained in the mixed solution-containing pellet, the solar cell encapsulating sheet obtained as described above has a desired amount of UV absorber and light stabilizer. The solar cell encapsulating sheet has excellent durability.

  In addition, when manufacturing a solar cell module described later, in order to improve the deaeration between the solar cell, the front surface side transparent protective member or the back surface side protective member and the solar cell sealing sheet, the solar cell sealing It is preferable to emboss the surface of the sheet.

  The method for embossing the surface of the solar cell encapsulating sheet is not particularly limited. The molten sheet immediately after being extruded from the T-die is embossed with an embossed pattern on the surface, and the embossed roll. There is a method of embossing the surface of the solar cell encapsulating sheet by supplying between the rubber rolls arranged opposite to each other and pressing the embossing roll against the molten sheet. In addition, after the solar cell sealing sheet once manufactured is heated again to a molten state, embossing may be performed as described above.

  And as a manufacturing method of the solar cell module using the sealing sheet for solar cells of the present invention, for example, (1) the surface side transparent protective member is provided on the surface of the solar cell via the front side solar cell sealing sheet, A back surface side protective member is laminated on the back surface via a back surface solar cell sealing sheet to produce a laminate, and the laminate is heated under reduced pressure to crosslink the front and back solar cell sealing sheets. A method for producing a solar cell module, in which a battery is sealed from the front and back with a front and back solar cell sealing sheet, and a protective member is laminated and integrated on the front and back surfaces of the solar cell via the front and back solar cell sealing sheet, (2) substrate A solar cell in which a thin-film solar cell element that generates electricity by light irradiation is formed is prepared, and a solar cell sealing sheet is formed on the surface of the solar cell substrate on which the solar cell element is formed. And a back surface side protective member is laminated on the solar cell encapsulating sheet to produce a laminate, and the solar cell encapsulating the solar cell encapsulating sheet by heating the laminate under reduced pressure. Examples include a method for producing a solar cell module in which an element is sealed from the front and back by a solar cell sealing sheet and a substrate, and a back surface side protective member is laminated and integrated on the solar cell element via the solar cell sealing sheet. .

  In addition, what is necessary is just to heat for 5 to 10 minutes as one minute half life temperature of an organic peroxide as conditions at the time of heating a laminated body. For example, if the one-minute half-life temperature of the organic peroxide is 160 ° C., the laminate may be heated at 160 ° C. for 5 to 10 minutes.

Moreover, it does not specifically limit as a board | substrate in the solar cell used by said (2), For example, the sheet | seat which consists of heat resistant resins, such as a polyimide, polyetheretherketone, polyethersulfone, is mentioned. Thin film solar cell elements include single crystal silicon, single crystal germanium, polycrystalline silicon, microcrystalline silicon and other crystalline semiconductors, amorphous semiconductors such as amorphous silicon, GaAs, InP, AlGaAs, CdS, CdTe, It is formed from a compound semiconductor such as Cu ₂ S, CuInSe ₂ and CuInS ₂ and an organic semiconductor such as phthalocyanine and polyacetylene in a general manner.

  As the solar cell used in the above (1), for example, a solar cell in which a silicon semiconductor element or a selenium semiconductor element wafer having a function of generating current when irradiated with light is connected directly or in parallel using an interconnector. Examples include a solar battery provided with a battery element.

  As described above, the method for producing a solar cell encapsulating sheet of the present invention impregnates the ethylene copolymer pellets with the mixed solution by supplying the ethylene copolymer pellets and the mixed solution to the rotating container. Since the rotating container is rotated, the organic peroxide is added to the ethylene copolymer pellet without applying friction stress or shear stress to the ethylene copolymer pellet and the organic peroxide as much as possible. It is possible to produce a mixed solution-containing pellet by uniformly impregnating without decomposing.

  Further, since the solid ultraviolet absorber and the solid light stabilizer are previously dissolved in the organic peroxide to form a uniform mixed solution, the solid ultraviolet absorber and the light stabilizer are converted into ethylene copolymer pellets. In the subsequent manufacturing process, the UV absorber and the light stabilizer are not accidentally dropped from the mixed solution-containing pellets. It can use for manufacture of the sealing sheet for solar cells, after containing and maintaining the quantity of ultraviolet absorber and light stabilizer, and the obtained amount of ultraviolet absorber and light stability is obtained for the sealing sheet for solar cells. The agent is contained in a desired amount with high accuracy.

  And since the solar cell sealing sheet is manufactured by extruding in a general manner from an extruder using the above mixed solution-containing pellets, the number of times the organic peroxide is supplied to the extruder is set to once, The organic peroxide is generally prevented from being decomposed by shortening the time for which it receives heat and friction in the extruder.

  Therefore, the obtained solar cell encapsulating sheet prevents the organic peroxide contained in the solar cell encapsulating sheet from being decomposed, has a uniform thickness, and does not have fish eyes or the like. Excellent surface smoothness.

  By sealing the solar cell using such a solar cell sealing sheet, the solar cell can be reliably sealed, and it is sufficiently crosslinked at the time of sealing the solar cell and has excellent weather resistance. Furthermore, since the solar cell encapsulating sheet contains a desired amount of ultraviolet absorber and light stabilizer with high accuracy, it is possible to suppress deterioration of the ethylene copolymer due to ultraviolet rays as much as possible, and the performance of the solar cell. Can be reliably maintained over a long period of time.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
100 parts by weight of dicumyl peroxide (one hour half-life temperature: 136 ° C.) as a liquid organic peroxide, 300 parts by weight of 2-hydroxy-4-n-octoxybenzophenone as an ultraviolet absorber, and as a light stabilizer 300 parts by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate is supplied to a stirrer equipped with a stirrer blade, and is pressurized and adjusted so that the temperature of dicumyl peroxide is 40 ° C. While stirring and rotating the stirring blade while heating and adjusting at normal pressure without reducing the pressure, 2-hydroxy-4-n-octoxybenzophenone and bis (2,2,6,6) were added to dicumyl peroxide. -Tetramethyl-4-piperidyl) sebacate was dissolved to prepare a mixed solution.

  Next, 100 parts by weight of ethylene-vinyl acetate copolymer pellets (vinyl acetate content: 25% by weight, melt flow rate: 20 g / 10 min) and 50 parts by weight of the above mixed solution are placed in a tumbler rotating container (tumbler mixer). The ethylene-vinyl acetate copolymer pellets are rotated by rotating the rotating container for 3 hours under normal pressure without pressurization and decompression while supplying and heating the ethylene copolymer pellets to 40 ° C. Were impregnated with the mixed solution to produce mixed solution-containing pellets. The mixed solution was a uniform solution during the process of impregnating the ethylene-vinyl acetate copolymer pellets.

  10 parts by weight of the resulting mixed solution-containing pellets and ethylene-vinyl acetate copolymer pellets containing no organic peroxide and other additives (vinyl acetate content: 25% by weight, melt flow rate: 20 g / 10 minutes) 90 parts by weight was supplied to an extruder, melted and kneaded at 120 ° C., and extruded from a T die at a discharge rate of 15 kg / hour to obtain a sealing sheet for a solar cell having a thickness of 500 μm.

(Example 2)
A mixed solution was produced in the same manner as in Example 1. Next, 100 parts by weight of ethylene-vinyl acetate copolymer pellets (vinyl acetate content: 25% by weight, melt flow rate: 20 g / 10 min), 50 parts by weight of the above mixed solution, triallyl isocyanurate 3 as a crosslinking aid Part by weight and 1 part by weight of 3-aminopropyltriethoxysilane as a coupling agent are supplied to a tumbler rotary container (tumbler mixer) and pressurized while heating so that the ethylene copolymer pellets are 40 ° C. Then, the rotating vessel is rotated for 3 hours under normal pressure without reducing pressure, and the ethylene-vinyl acetate copolymer pellet is impregnated with the mixed solution, triallyl isocyanurate and 3-aminopropyltriethoxysilane and mixed. Solution-containing pellets were produced. The mixed solution was a uniform solution during the process of impregnating the ethylene-vinyl acetate copolymer pellets.

  10 parts by weight of the resulting mixed solution-containing pellets and ethylene-vinyl acetate copolymer pellets containing no organic peroxide and other additives (vinyl acetate content: 25% by weight, melt flow rate: 20 g / 10 minutes) 90 parts by weight was supplied to an extruder, melted and kneaded at 120 ° C., and extruded from a T die at a discharge rate of 15 kg / hour to obtain a sealing sheet for a solar cell having a thickness of 500 μm.

(Comparative Example 1)
100 parts by weight of ethylene-vinyl acetate copolymer pellets (vinyl acetate content: 25% by weight, melt flow rate: 20 g / 10 min), dicumyl peroxide (one hour half-life temperature: 136) as a liquid organic peroxide 10 ° C.), 30 parts by weight of 2-hydroxy-4-n-octoxybenzophenone as an ultraviolet absorber, and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate 30 as a light stabilizer. Without mixing the parts by weight in advance, each is supplied to a tumbler rotating container (tumbler mixer) and heated under normal pressure without pressurization and depressurization while heating the ethylene copolymer pellets to 40 ° C. Rotate the rotating vessel for 3 hours to turn ethylene-vinyl acetate copolymer pellets into dicumyl peroxide, 2-hydroxy- -n- octoxybenzophenone and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate impregnated with to produce an organic peroxide-containing pellets.

  10 parts by weight of the obtained organic peroxide-containing pellets and ethylene-vinyl acetate copolymer pellets containing no organic peroxide and other additives (vinyl acetate content: 25% by weight, melt flow rate : 20 g / 10 min) 90 parts by weight was supplied to an extruder, melted and kneaded at 120 ° C., and extruded from a T die at a discharge rate of 15 kg / hour to obtain a sealing sheet for a solar cell having a thickness of 500 μm.

  The mixed solution-containing pellet and the organic peroxide-containing pellet were visually observed, and the appearance and permeability of the pellet were measured based on the following criteria. The results are shown in Table 1.

(appearance)
The appearance of the mixed solution-containing pellet and the organic peroxide-containing pellet is visually observed, and “○” indicates that the powder is not attached to the pellet surface, and “×” indicates that the powder is attached to the pellet surface. As evaluated.

(Penetration)
20 kg each of the mixed solution-containing pellets and the organic peroxide-containing pellets are collected, the collected pellets are placed on a 10-mesh sieve, the sieve is placed on a sieve vibrator, and the sieve is vibrated for 10 minutes. The total weight of the powder released from the surface was measured.

Claims (3)

A solid ultraviolet absorber and a solid light stabilizer are dissolved at 30 to 45 ° C. in a liquid organic peroxide to produce a mixed solution, and the ethylene copolymer pellets and the mixed solution are mixed into a rotating container. The mixture solution is impregnated in liquid form in the ethylene copolymer pellets by rotating the rotating container while heating the ethylene copolymer pellets and supplying the mixture solution-containing pellets. A method for producing a solar cell encapsulating sheet, wherein the mixed solution-containing pellet is supplied to an extruder, melted and kneaded, and extruded from the extruder to produce a solar cell encapsulating sheet. The method for producing a sealing sheet for a solar cell according to claim 1, wherein a crosslinking aid is supplied into the rotating container to impregnate the ethylene copolymer pellets with the crosslinking aid. The method for producing a sealing sheet for a solar cell according to claim 1 or 2, wherein a coupling agent is supplied into a rotating container to impregnate the ethylene copolymer pellets with the coupling agent.