JP2015153977A - Seal material for solar cell and laminated seal material for solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal material for a solar cell excellent in water cut-off properties.SOLUTION: The seal material for a solar cell includes: an urethane resin (A); and a plurality of particles, dispersed in the urethane resin, having cavities inside thereof (B). The plurality of particles (B) include thermally expanded foam particles, for instance.

Description

  The present invention relates to a solar cell sealing material and a solar cell laminated sealing material formed of urethane resin.

  Conventionally, a sealing material composed of a foam has been used in various fields, and has recently been used in solar cell applications. Specifically, when the peripheral edge of the solar cell panel is fixed to the support frame material, the sealing material is disposed between the panel peripheral edge and the support frame material, and water or the like enters the panel. To prevent. Patent Document 1 includes a polyurethane foam layer having a water-stopping property and a urethane-based elastomer layer having insulating properties as such a solar cell sealing material, and the polyurethane foam layer and the urethane-based elastomer layer are chemically bonded. Discloses a water-resistant polyurethane foam sealant that is more closely adhered to. For the polyurethane foam layer of this sealing material, Super Seal WB, Super Sheet H, etc., manufactured by Nihon Hojo Co., Ltd., known as open cells, are used in order to ensure flexibility and water stoppage.

JP 2010-235734 A

However, if the polyurethane foam layer is open-celled, its sealing performance is limited. On the other hand, in order to prevent the solar cell panel from being submerged from the side, the solar cell sealing material is desired to have high water-stopping properties. The solar cell sealing material disclosed in Patent Document 1 has the required performance. Not satisfied enough.
This invention is made | formed in view of the above problem, and makes it a subject to provide the sealing material for solar cells excellent in the water-stopping property, and the laminated sealing material for solar cells.

As a result of intensive studies, the present inventor can improve the water-stopping property of the sealing material by dispersing a plurality of particles having a hollow portion in the urethane resin and forming the hollow portion as foam bubbles. The present invention was found to be useful as a sealing material for solar cells, and the following invention was completed. That is, the present invention provides the following (1) to (12).
(1) A solar cell sealing material having a urethane resin (A) and a plurality of particles (B) dispersed in the urethane resin (A) and having a hollow portion therein.
(2) The solar cell sealing material according to (1), wherein the plurality of particles (B) include expanded foam particles, and an average particle diameter is 40 to 200 μm.
(3) The solar cell sealing material according to (1) or (2), wherein the urethane resin (A) is a polyether-based urethane.
(4) The solar cell sealing material is obtained by curing the sealing material composition, and the sealing material composition includes at least a hindered amine light stabilizer. The sealing material for solar cells of crab.
(5) The solar cell sealing material is obtained by curing a sealing material composition, and the sealing material composition includes at least an ultraviolet absorber composed of a benzotriazole-based compound. 4) The solar cell sealing material according to any one of the above.
(6) The sealing material for solar cells according to any one of (1) to (5), wherein the closed cell ratio is 70% or more and the 20% compressive stress at 20 ° C. is 0.05 to 0.7 MPa.
(7) A laminated sealing material for solar cells, comprising: the solar cell sealing material according to any one of (1) to (6) above; and a resin film laminated on one surface of the solar cell sealing material.
(8) The solar cell panel, a fixing member that fixes a peripheral end of the solar cell panel, and any one of the above (1) to (7) disposed between the fixing member and the solar cell panel A solar cell module comprising the solar cell sealing material or the solar cell laminated sealing material.
(9) A solar cell obtained by curing a sealing material composition including a urethane resin raw material and a plurality of particles having a hollow portion therein to form a cell sealing material in which bubbles are formed by the hollow portion of the particle. Manufacturing method for sealing material.
(10) Claims wherein a plurality of foamable particles are heated and foamed to obtain a plurality of foamed particles having a cavity therein, and the foamed particles and a urethane resin raw material are mixed to obtain the sealing material composition. Item 10. A method for producing a solar cell panel sealing material according to Item 9.
(11) After mixing a part of the polyol component of the urethane resin raw material and a plurality of expandable particles, the expandable particles are heated and expanded to form expanded particles having a cavity therein, A step of obtaining a mixture containing expanded particles and a part of a polyol component, a step of obtaining at least a remainder of the polyol component of the urethane resin raw material and an isocyanate compound in the mixture to obtain a sealing material composition, and the sealing material composition A method for producing a solar cell panel sealing material according to (9) or (10), comprising: a step of heat-curing an object to obtain the solar cell sealing material.
(12) A sealing material composition including a urethane resin raw material and a plurality of particles having cavities therein is cured in a state of being superimposed on a resin film, and bubbles are formed by the cavities of the particles. The manufacturing method of the laminated sealing material for solar cells which obtains the laminated sealing material for solar cells by which the said resin film was laminated | stacked on the single side | surface of the sealing material for solar cells.

  ADVANTAGE OF THE INVENTION According to this invention, the sealing material for solar cells and the laminated sealing material for solar cells excellent in water-stopping property can be provided.

It is typical sectional drawing which shows an example of the laminated sealing material for solar cells of this invention. It is a fragmentary perspective view which shows the solar cell module to which the sealing material for solar cells of this invention was applied. It is a fragmentary sectional view which shows the solar cell module to which the sealing material for solar cells of this invention was applied.

Hereinafter, the present invention will be described in more detail with reference to embodiments.
[Sealant]
The sealing material for solar cells according to the present invention has a urethane resin (A) and a plurality of particles (B) dispersed in the urethane resin (A) and having hollow portions therein. In the present invention, with such a configuration, the solar cell sealing material is formed from the urethane resin (A) having a plurality of bubbles therein, and a solar cell sealing material having excellent water-stopping property can be provided. .
Moreover, it is preferable that the sealing material for solar cells which concerns on this invention is a foam. As will be described later, the foam may be a cured product foamed when the sealing material composition is cured, but the foamed material should have been cured from the sealing material composition containing foamed foamed particles. preferable. Thereby, the various performances of the sealing material for solar cells can be maintained satisfactorily.

[Urethane resin (A)]
The urethane resin (A) is obtained by reacting a polyol component and an isocyanate compound. As the urethane resin (A), it is preferable to use a polyether-based urethane whose polyol component is a polyether polyol. Hereinafter, raw materials (polyol component, isocyanate compound, etc.) that are constituent elements of the urethane resin (A) may be collectively referred to as urethane resin raw materials.
Polyether polyol is harder to hydrolyze with moisture than polyester polyol. Therefore, when it contacts with water | moisture content, it can prevent that it swells and embrittles by hydrolysis, and is used suitably for the sealing material for solar cells.

<Polyether polyol>
Polyether polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, sucrose and other polyhydric alcohols such as ethylene oxide, propylene oxide, A polyether polyol to which an alkylene oxide such as butylene oxide is added is preferably used.
In these, the polyoxyalkylene glyceryl ether which added said C2-C4 alkylene oxide to glycerol is more preferable, and polyoxypropylene glyceryl ether is especially preferable.
The number average molecular weight of the polyether polyol is preferably about 500 to 10,000, and more preferably about 1500 to 4500. The number average molecular weight is usually calculated from the hydroxyl value of the polyol component. The hydroxyl value in the present invention is measured by a method specified in JIS K0070.

<Isocyanate compound>
Isocyanate compounds include tolylene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), crude MDI, polymeric MDI, uretdione modified MDI, carbodiimide modified MDI, hydrogenated MDI, hexamethylene diisocyanate (HDI), naphthalene diisocyanate, paraphenylene diisocyanate. , Xylene diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, etc., among which tolylene diisocyanate (TDI) is used. preferable.

The compounding amount of the isocyanate compound is preferably 20 to 70 parts by mass, more preferably 38 to 57 parts by mass, per 100 parts by mass of the polyol component. The isocyanate index (percentage of isocyanate groups with respect to active hydrogen groups capable of reacting with isocyanate groups) is preferably 90 to 130, more preferably 105 to 115.
The above isocyanate compound may be blended in a sealing material composition to be described later as it is, or may be blended in a sealing material composition after preliminarily reacting with the polyol. As the prepolymer, a TDI prepolymer is preferably used. Hereinafter, when an isocyanate compound is described, a prepolymer is included.

The solar cell sealing material of the present invention is obtained by curing a sealing material composition containing particles such as a foamed particle for forming a polyether polyol and an isocyanate compound (that is, a urethane resin raw material) and particles (B). More preferably, the sealing material composition further includes at least one selected from an amine catalyst, a phosphorus-based antioxidant, a hindered amine-based light stabilizer, and an ultraviolet absorber. It is particularly preferable that
The polyether polyol and the isocyanate compound are the main components in the sealing material composition, and the total amount of these is preferably 50% by mass, more than 70% by mass with respect to the entire sealing material composition. More preferably, it is more preferably 85% by mass or more.

<Amine catalyst>
As amine catalysts, pentamethyldiethylenetriamine, N-ethylmorpholine, N, N-dimethylethanolamine, triethylamine, triethylenediamine, tripropylamine, tributylamine, diethanolamine, dimethylcyclohexylamine, diethyltriamine, tetramethylhexanediamine, tetramethyl Hexamethylenediamine, tetramethylpropanediamine, tetramethylethylenediamine, pentamethyldipropylenetriamine, hexadecyldimethylamine, N-methyldicyclohexylamine, N-dimethylbenzylamine, N-trioxyethylene-N, N-dimethylamine, N , N-dimethyl-N-hexanolamine, dimethylaminomorpholine, dimethylaminoethylmorpholine, N-methyl Ruphorin, N-octadecylmorpholine, tetramethylguanidine, dimethylpiperazine, N-methyl-N ′-(2-dimethylamino) ethylpiperazine, N-methyl-N ′-(2-hydroxyethyl) piperazine, N, N ′, N'-trimethylaminoethylpiperazine, bisdimethylaminoethyl ether, diazobicycloundecene, 2-methyl-1,4-diazo (2,2,2) bicyclooctane and the like are used.
In the sealing material composition, the content of the amine catalyst is preferably 0.01 to 5 parts by mass and more preferably 0.03 to 1 part by mass per 100 parts by mass of the polyol component.

<Phosphorus antioxidant>
Examples of phosphorus antioxidants include tris (2-ethylhexyl) phosphite, bis (tridecyl) pentaerythritol diphosphite, diphenyl monodecyl phosphite, tris (nonylphenyl) phosphite, tris (dipropylene glycol) phosphite, Triphenyl phosphite, tristearyl phosphite and the like are used.
In the sealing material composition, the content of the phosphorus antioxidant is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass per 100 parts by mass of the polyol component.

<Hindered amine light stabilizer>
Examples of hindered amine light stabilizers include bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis (2 , 2,6,6-tetramethyl-4-piperidinyl) sebacate, poly ((6-((1,1,3,3-tetramethylbutyl) amino) -s-tetrazine-2,4-didyl) (2 , 2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene (2,2,6,6-tetramethyl-4-piperidyl) imino))), bis (1,2,2,6,6 Hindered piperidine compounds such as -pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate can be used. Among these, since it is liquid and easy to handle, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl seba Mixtures with Kate are preferred. By blending a hindered amine light stabilizer in the sealing material composition, the light stability of the sealing material can be improved, and a sealing material suitable for solar cell applications can be provided.
In the sealing material composition, the content of the hindered amine light stabilizer is preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass per 100 parts by mass of the polyol component.

<Ultraviolet absorber>
Examples of the ultraviolet absorber include benzotriazole compounds such as 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, 2,4-di-tert-butylphenyl-3,5-di Hydroxybenzoate compounds such as -tert-butyl-4-hydroxybenzoate are used. Among these, benzotriazole compounds such as 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol are preferable. By mix | blending a ultraviolet absorber with a sealing material composition, the deterioration by the ultraviolet-ray to a sealing material is prevented, and durability of the sealing material for solar cells is improved.
In the sealing material composition, the content of the ultraviolet absorber is preferably 0.3 to 3 parts by mass and more preferably 0.5 to 2 parts by mass per 100 parts by mass of the polyol component.

[particle]
The particles (B) have hollow portions inside and are dispersed in the urethane resin (A). The average particle size of the particles (B) varies greatly depending on the thickness of the solar cell sealing material to be produced, but is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 40 μm or more, and preferably 300 μm or less. More preferably, it is 200 micrometers or less, More preferably, it is 150 micrometers or less. By setting the average particle diameter to 300 μm or less, even when the solar cell sealing material is extremely thin, closed cells are formed by the particles (B), and the solar cell sealing material can function as a solar cell sealing material. Moreover, impact resistance and sealing performance can be made favorable by setting it as 10 micrometers or more.
The plurality of particles (B) dispersed in the urethane resin (A) may have a single distribution or a different distribution. For example, it is preferable to show three types of particle size distributions. This is because more particles (B) can be contained than particles (B) having a single particle size distribution. “Showing different distributions” means that there are two or more peaks when, for example, a particle distribution graph is created by measuring the particle diameter of 100 particles (B) by the method described later. “Showing a single distribution” and “showing three kinds of particle size distributions” mean that there are one peak and three peaks, respectively. Examples of the shape of the particles (B) include a spherical shape, a plate shape, a needle shape, and an indefinite shape. From the viewpoint of further enhancing the packing properties and dispersibility of the particles (B), the particles (B) are preferably spherical. The aspect ratio of the spherical particles is 5 or less, preferably 2 or less, more preferably 1.2 or less. In the present specification, the average particle diameter means an average value of measured values when the size of primary particles of 100 particles in the observed visual field is measured using a scanning electron microscope, an optical microscope, or the like. It is. The average particle diameter means an average value of the diameters of the particles when the particles are spherical, and means an average value of the major diameters of the particles when the particles are non-spherical. The aspect ratio is represented by the ratio of the minor axis to the major axis (average value of major axis / average value of minor axis).

The particles (B) are so-called hollow particles having an outer shell and having a hollow portion therein. In the present invention, by forming bubbles with hollow particles, it is possible to reduce the thickness while improving the compression stress of the solar cell sealing material. The particles (B) preferably have one cavity inside. The particles (B) are preferably organic particles, that is, the material of the outer shell of the particles (B) is preferably an organic compound.
The porosity of the particles (B) is preferably 50% or more, more preferably 80% or more, still more preferably 90% or more, and preferably 98% or less, more preferably 97% or less, still more preferably 96. % Or less. When the porosity is 50% or more, the impact resistance, sealing property and flexibility of the solar cell sealing material are increased, and when the porosity is 80% or more or 90% or more, it is further increased. When the porosity is 98% or less, the strength of the particles (B) is increased and cracks are hardly generated in the outer shell, and when 97% or less or 96% or less, the strength is further increased. In addition, in this specification, the porosity means the volume ratio which represented the volume of the space | gap part which occupies in the said whole particle | grain (B) volume as a percentage (%). Specifically, for example, 100 particles are arbitrarily extracted from a photograph taken with a microscope, and the major axis and minor axis of the particle outer diameter and the major axis and minor axis of the particle hole portion are measured. And the porosity of each particle | grain is calculated with a following formula, and let the average value of the porosity of 100 particle | grains be the porosity of a particle | grain (B).
Porosity (volume%) = ((hole portion long diameter + hole portion short diameter) / (outer diameter long diameter + outer diameter short diameter)) ³ × 100

  The particles (B) are preferably expanded particles that have been expanded so as to form cavities therein. By using the expanded particles, the impact resistance and flexibility of the solar cell sealing material are further enhanced. The expanded particles are preferably expanded particles obtained by expanding thermally expandable particles, and more preferably expanded particles obtained by thermally expanding thermally expandable microcapsules. Thermally expandable microcapsules are those in which a volatile substance such as a low boiling point solvent is encapsulated inside the outer shell resin, and the outer shell resin is softened by heating, and the encapsulated volatile substance volatilizes or expands. The outer shell expands by the pressure to increase the particle diameter, resulting in foamed particles. The temperature at which the thermally expandable microcapsules are expanded is not particularly limited, but is preferably higher than the expansion start temperature described later and lower than the maximum expansion temperature.

  The outer shell of the thermally expandable microcapsule is preferably formed from a thermoplastic resin. Thermoplastic resins include vinyl polymers such as ethylene, styrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, butadiene, chloroprene, and copolymers thereof; polyamides such as nylon 6 and nylon 66; and polyesters such as polyethylene terephthalate. One kind or two or more kinds selected can be used, but an acrylonitrile copolymer is preferable from the viewpoint that the encapsulated volatile substance hardly penetrates. Examples of volatile substances encapsulated in the thermally expandable microcapsule include propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, hexane, heptane and other hydrocarbons having 3 to 7 carbon atoms; petroleum Ethers; methane halides such as methyl chloride and methylene chloride; chlorofluorocarbons such as CCl3F and CCl2F2; one or more low boiling points selected from tetraalkylsilanes such as tetramethylsilane and trimethylethylsilane Liquid is used. Preferable examples of the thermally expandable microcapsule include a microcapsule in which a copolymer of acrylonitrile and vinylidene chloride is used as an outer shell resin and a hydrocarbon having 3 to 7 carbon atoms such as isobutane is encapsulated.

The thermally expandable microcapsule before foaming has an average particle diameter of preferably 1 μm or more, more preferably 4 μm or more, and preferably less than 50 μm, more preferably less than 40 μm. By setting the average particle diameter to be equal to or larger than the above lower limit value, it is difficult for the particles to aggregate and it is easy to uniformly disperse the thermally expandable microcapsules in the resin. Moreover, when it becomes a foam by setting it as an upper limit or less, it can prevent that the number of bubbles of a thickness direction decreases or an bubble becomes large, and can stabilize quality, such as a mechanical property.
The thermally expandable microcapsules preferably expand to become the above-mentioned expanded particles so that the average particle diameter is preferably 2 times or more, preferably 10 times or less. Moreover, 95-150 degreeC is preferable and, as for the expansion start temperature of a thermally expansible microcapsule, it is more preferable that it is 105-140 degreeC. Further, the maximum expansion temperature is preferably 120 to 200 ° C, more preferably 135 to 180 ° C.
Examples of commercially available thermal expandable microcapsules include “EXPANCEL” manufactured by Nippon Philite Co., Ltd., “Advancel” manufactured by Sekisui Chemical Co., Ltd., “Matsumoto Microsphere” manufactured by Matsumoto Yushi Seiyaku Co., Ltd., “ Microsphere "etc. are mentioned.

  In the present invention, the expandable particles (unexpanded) for forming the particles (B) are in 100% by mass of the sealing material composition for forming the solar cell sealing material, preferably 0.1% by mass or more, More preferably, 1% by mass or more is blended, and preferably 30% by mass or less, more preferably 10% by mass or less. When the content of the particles (B) is not less than the above lower limit and not more than the above upper limit, the sealing property and impact absorbing property of the solar cell sealing material and the strength of the sheet are increased in a well-balanced manner.

  In addition to the particles (B), the solar cell sealing material in the present invention may further contain particles (C) dispersed in the urethane resin (A) and having no cavity inside. The particles (C) may be any of inorganic particles, organic particles, and organic-inorganic composite particles.

  As the particles (C), for example, one kind selected from alumina, synthetic magnesite, silica, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, talc, mica, and hydrotalcite or Examples include inorganic particles composed of two or more inorganic compounds, and both inorganic particles and organic particles may be used.

[Other ingredients]
The sealing material composition may contain additives such as a colorant, a viscosity modifier, a light diffusing agent, a flame retardant, and a diluent, as necessary, in addition to the above additives.

[Thickness]
The solar cell sealing material is preferably a sheet-like member, and the thickness of the solar cell sealing material is preferably 0.05 mm or more, and preferably 2.5 m or less. In the present invention, when the thickness is 0.05 mm or more, high impact absorption performance and sealing properties can be secured, and when the thickness is 2.5 m or less, the solar cell panel described later is made thinner and smaller. It becomes possible to reduce the weight, and the cost-effectiveness is improved. In addition, the designed gap between the solar cell panel and the support frame material is prevented from becoming unnecessarily thick, and the solar cell module with the solar cell sealing material attached is inserted into the support frame material. Becomes easy. From these viewpoints, the thickness is more preferably 0.1 mm or more, and particularly preferably 0.5 mm or more. The thickness is more preferably 2 mm or less, and particularly preferably 1 mm or less.

[Foaming ratio]
In the present invention, the expansion ratio of the solar cell sealing material is preferably 2 times or more, more preferably 2.5 times or more, and preferably 8 times or less, more preferably 7 times or less. When the expansion ratio is equal to or higher than the above lower limit value, it is possible to improve impact absorption, sealing properties, and flexibility. For example, even in a portion where solar cell sealing materials are overlapped, compression becomes easy. Moreover, when it becomes below the said upper limit, the intensity | strength of the sealing material for solar cells becomes high, and it becomes possible to improve impact resistance etc.

[Closed cell ratio and compressive stress]
The solar cell sealing material of the present invention preferably has a closed cell ratio of 70% or more and a 20% compressive stress at 20 ° C. of 0.05 to 0.7 MPa. As described later, the sealing material for solar cells makes the closed cell ratio and the compressive stress within a certain range, so that even when a resin film is laminated, the sealing property and the compression characteristic are good, and the waterproofing is sufficient. Secures dust resistance and impact resistance. More specifically, when the closed cell ratio is 70% or more, it becomes difficult for moisture to enter the bubbles inside the solar cell sealing material, and it becomes easy to ensure high sealing performance. Moreover, by being 70% or more, the air in a bubble becomes difficult to leak outside and it becomes easy to make the range of a compressive stress into said range. From these viewpoints, the closed cell ratio is preferably 80% or more, more preferably 90% or more, and further preferably 95% or more. In the sealing material of the present invention, each of the hollow portions of the particles (B) usually becomes closed cells, and the closed cell rate is easily increased.

  Moreover, the solar cell sealing material has a 20% compressive stress at 20 ° C. of 0.05 MPa or more, so that the solar cell is exposed to wind and rain, and even if the solar cell is cleaned by a washing machine ( For example, it is possible to prevent moisture from entering the inside of the solar cell panel. Moreover, the intensity | strength of the sealing material for solar cells can also be made favorable. In addition, the solar cell sealing material has a good flexibility and a sufficient shock absorption when the 20% compression stress at 20 ° C. is 0.7 MPa or less, and the solar cell panel or the like is damaged by the impact. It is prevented. Furthermore, resistance at the time of inserting the solar cell panel to which the solar cell sealing material or the solar cell laminated sealing material described later is attached into the support frame member is lowered, and the workability is improved. In addition, when the compressive stress is in the above range, sufficient water tightness can be obtained without using an adhesive to improve the adhesion between the solar cell panel and the support frame. For this reason, it is prevented that workability | operativity falls by the adhesiveness of an adhesive. In addition, the compressive stress of the sealing material which concerns on embodiment of this invention is calculated | required based on JISK6767.

The closed cell ratio is measured, for example, in the following manner.
A planar square test piece having a side of 5 cm is cut out from the solar cell sealing material. The thickness of the test piece is measured, the apparent volume V1 of the test piece is calculated, and the weight W1 of the test piece is measured. Next, the apparent volume V2 occupied by the bubbles is calculated based on the following formula. The density of the resin constituting the test piece is ρg / cm ³ .
Apparent volume occupied by bubbles V2 = V1-W1 / ρ
Subsequently, the test piece is submerged in distilled water at 23 ° C. to a depth of 100 mm from the water surface, and a pressure of 15 kPa is applied to the test piece over 3 minutes. After releasing the pressure in water, the test piece is taken out of the water to remove the water adhering to the surface of the test piece, the weight W2 of the test piece is measured, and the open cell rate F1 and the closed cell rate F2 are calculated based on the following formulas. calculate.
Open cell ratio F1 (%) = 100 × (W2−W1) / V2
Closed cell ratio F2 (%) = 100-F1

  The solar cell sealing material of the present invention may be used alone as a solar cell sealing material, but may be used with another layer provided on one or both sides of the solar cell sealing material. Good. For example, it is preferable to be used as a solar cell laminated sealing material comprising a solar cell sealing material and a resin film laminated on one surface of the solar cell sealing material.

[Laminated sealing material for solar cells]
Hereinafter, the structure of the laminated sealing material for solar cells of the present invention will be described in more detail. The laminated sealing material for solar cells includes the above-described sealing material for solar cells and a resin film laminated on one surface of the sealing material for solar cells. Here, the laminated sealing material for solar cells is one in which a resin film is integrated with the sealing material for solar cells, and the resin film and the sealing material for solar cells may be bonded or fused, but they are not necessarily bonded. The resin film need not be fused and may be laminated to such an extent that the resin film can be easily peeled off from the solar cell sealing material. However, it is preferable that the sealing material composition before the curing reaction is thermally cured after being spread on the resin film. This is because it is practically difficult to integrate the solar cell sealing material after the curing reaction into the resin film without pretreatment with a primer or the like. The resin film and the solar cell sealing material are used as a sealing material in a solar cell panel or the like by integrating them. By providing the resin film with the laminated sealing material for solar cells, it becomes possible to improve the weather resistance, insulation, and moisture permeation performance.

FIG. 1 shows an example of a laminated sealing material for solar cells, and shows a laminated sealing material 10 for solar cells in which a resin film 13 is laminated on one surface of a sealing material 11.
Such a solar cell laminated sealing material 10 has high compressibility even if a resin film having poor compression characteristics is laminated because the solar cell sealing material 11 has the above-described compressive stress and has excellent compression characteristics. And shock absorption performance can be ensured. Moreover, the laminated sealing material for solar cells of the present invention is provided with a resin film, so that bubbles are formed by the particles (B) and the closed cell ratio is in the above range, so that moisture can enter. It can prevent more appropriately. The laminated sealing material for solar cell panels of the present invention can exhibit high sealing performance without laminating an adhesive layer on the sealing material.

[Resin film]
As the resin film, it is preferable to use a resin excellent in breaking strength and dielectric breakdown voltage. Specific examples of resins that can be used for the resin film include olefin resins such as polyethylene (PE) resins and polypropylene (PP) resins, ethylene-vinyl alcohol copolymer (EVOH) resins, polyethylene terephthalate (PET). ), Polyester resins such as polybutylene terephthalate (PBT), polystyrene (PS) resins, polycarbonate (PC) resins, polyacetal (POM) resins, polyethersulfone (PES) resins, polytetrafluoroethylene ( PTFE) resin, polyimide resin, phenol resin, epoxy resin, ABS resin, polyphenylene sulfide (PPS) resin, liquid crystal polymer (LCP) resin, and the like. Moreover, you may laminate | stack (coextrusion, lamination) several said resin.
The resin film has low adhesiveness to the solar cell sealing material and is easily peeled off. Therefore, the resin film is bonded and integrated through a primer layer or an adhesive layer, or a coupling agent is sealed as described later. It is more preferable to mix | blend or apply | coat to a composition and / or a resin film.

  In this invention, the sealing material for solar cells can be reinforced by using the said resin film. Moreover, in this invention, since the sealing material for solar cells is a foam which has a bubble, dielectric breakdown strength and moisture permeability may be inferior, but the laminated sealing material for solar cells is provided with these resin films. In addition, the dielectric breakdown strength and moisture permeability can be improved. Further, from the viewpoint of particularly improving the dielectric breakdown strength, the thickness and expansion ratio of the solar cell sealing material and the thickness of the resin film are important factors. From this point of view, it is preferable that the thickness of the sealing material for solar cells and the expansion ratio are in the above-described range, while the thickness of the resin film is 0.01 to 0.25 mm. The thickness of the resin film is more preferably 0.02 to 0.15 mm. In the laminated sealing material of the present invention, for example, the thickness of the sealing material is set to 0.1 mm or more, and the foaming ratio is set to 8 times or less, and the thickness of the resin film is set to 0.01 mm or more, whereby the dielectric breakdown voltage is appropriately set. Since it can be made large and the moisture permeability can be reduced, it is suitable as a sealing material for solar cells. Moreover, desired performance can be obtained while preventing the material cost from increasing by setting the thickness of the resin film to 0.25 mm or less. In addition, when the thickness of the resin film is 0.25 mm or less, the rigidity of the laminated sealing material is prevented from becoming too high. For example, when it is wound into a roll shape, problems such as curling are generated. Is less likely to occur. Furthermore, when the thickness of the resin film is 0.15 mm or less, the followability to the uneven surface is improved, and the performance as a sealing material can be further enhanced. Moreover, you may mix | blend ultraviolet-ray deterioration inhibitors, such as a ultraviolet absorber, with a resin film from a light-resistant viewpoint.

  Among the above-mentioned resins, olefin resin films such as polyethylene films are suitable from the viewpoint of excellent water vapor barrier properties, weather resistance, and light resistance, and hindered amine light stabilizers, ultraviolet absorbers, antioxidants. A PE resin film formulated with an ultraviolet deterioration preventing agent such as the above is also preferably used. Further, from the viewpoint of the extensibility of the resin film, olefin-based, particularly PE or PP-based resin films are desirable. If stretchable resin films are used, when solar cell sealing materials are applied around solar cells, etc., they can be in close contact with tension, thereby improving adhesion to solar cell panels, etc. As a result, water tightness can be improved. From these viewpoints, when the laminated sealing material is used for solar cell panel applications, an olefin resin film is suitable for the resin film.

The moisture vapor permeability (moisture permeability) in the moisture vapor permeability test defined in JIS Z 0208 of the resin film is desirably 30 g / m ² · day or less. If the moisture permeability is 30 g / m ² · day or less, the thickness of the resin film is in the above range, and for example, when used for solar cell panel applications, Performance degradation can be prevented. From the above viewpoint, a preferable range of moisture permeability is 10 g / m ² · day or less, and more preferably 5 g / m ² · day or less.

  As such a resin film having low moisture permeability, among the above-mentioned ones, olefin resin films such as polyethylene films and polypropylene films, EVOH resin films, polyester resin films such as PET and PBT, etc. should be used. Can do. Examples of the polyethylene constituting the polyethylene film include low density polyethylene, linear low density polyethylene, high density polyethylene, and mixtures thereof. Furthermore, ethylene-vinyl acetate copolymer (EVA) may be mixed as described above or coextruded. Further, examples of the polypropylene constituting the polypropylene film include a homopolymer type, a copolymer type, a block polymer type, and an ethylene-propylene terpolymer. Further, the polyethylene and EVA may be mixed or coextruded.

The elongation at break in the machine direction (MD direction) in the tensile test at 20 ° C. of the resin film is desirably 100% or more. If this value is 100% or more, there is no decrease in handling at the time of manufacture due to the above-described curl, and the adhesion can be improved by allowing the laminated sealing material to follow the surface of the solar cell module. Examples of the resin film having an elongation at break of 100% or more include olefin resin films, EVOH resin films, polyester resin films, PTFE resins, and polyimide resins among the resin films.
Furthermore, from the viewpoint of light resistance of the laminated sealing material for solar cells, it is preferable that the elongation at break is maintained even after 1000 hours based on the UV exposure test conditions defined in UL746C of the resin film. That is, even after the above test, the breaking elongation in the vertical direction is preferably 70% or more. Thus, as a resin having a high elongation at break even after UV exposure, a resin in which an ultraviolet degradation inhibitor is blended is used. As UV degradation inhibitors, hindered amine light stabilizers, benzotriazole ultraviolet absorbers, hindered phenol antioxidants, light-shielding pigments based on titanium oxide and / or carbon black, and mixtures thereof are used. it can.
Moreover, the laminated sealing material for solar cells preferably has a moisture permeability of 30 g / m ² · day or less and a breaking elongation of 70% or more after 1000 hours of UV exposure test conditions. As such a resin film, the above-mentioned polyolefin resin film or EVOH resin film is preferably blended with an ultraviolet degradation inhibitor. Specifically, Vegitalon Super Kirinashi (product name, Sekisui Film Co., Ltd.) Company-made), Hanano Hikaru UV Long (product name, manufactured by Sekisui Film Co., Ltd.) and the like.

Furthermore, it is preferable that the sealing material for solar cells and the laminated sealing material for solar cells of the present invention have the following compression set.
[Compression set]
When the compression set is large, the solar cell sealing material and the solar cell laminated sealing material have a reduced repulsive force (compression stress) in a long-term compression state, thereby reducing impact performance and gap followability. This causes water (including water vapor) to enter. Therefore, the solar cell sealing material and the solar cell laminated sealing material of the present invention preferably have a small compression set, and specifically, the compression set is preferably 15% or less, and preferably 10% or less. It is further desirable.
When the compression set is 15% or less, the sealing property is improved and it is not necessary to use a so-called double-sided tape in which an adhesive layer is provided on both sides, for example, in order to prevent a gap. By not providing the pressure-sensitive adhesive layer on one side (preferably on either side), it is not necessary to lower the impact performance in order to exert the adhesive effect of the pressure-sensitive adhesive, and the solar cell has higher impact resistance performance. Sealing material and laminated sealing material for solar cell can be provided. In addition, when used for solar cell panels and inserted into a frame, the adhesive layer disposed on the outside is omitted, eliminating excessive frictional resistance due to the adhesive, and for solar cells corresponding to the core material The seal material is not deformed. In this invention, the laminated sealing material for solar cells is likely to have a lower value of compression set by having a resin film.

Moreover, it is preferable that the laminated sealing material for solar cells of the present invention has the following dielectric breakdown voltage and moisture permeability.
[Dielectric breakdown voltage]
The laminated sealing material for solar cells of the present invention preferably has a dielectric breakdown voltage of 4 kV or higher, more preferably 5 kV or higher. When the solar cell panel is held by, for example, a metal frame, the solar cell laminated sealing material is usually disposed so as to contact the metal frame, but at that time, it is necessary to insulate from the metal frame. . This is because when the electricity charged in the metal frame flows to the solar cell panel through the solar cell laminated sealing material, the power generation capacity of the cell is reduced (deteriorated). When the dielectric breakdown voltage is 4 kV or more, it becomes possible to substantially insulate the solar cell sealing material or solar cell laminated sealing material from the metal frame. In the present invention, the laminated sealing material for solar cells has a resin film, so that the dielectric breakdown voltage can be easily increased.

[Moisture permeability]
The laminated sealing material for solar cells of the present invention preferably has a moisture permeability of 30 g / m ² · day or less, more preferably 10 g / m ² · day or less. By setting the moisture permeability to the upper limit value or less, water (including water vapor) can be prevented from entering the solar battery panel, and a decrease in the power generation capacity of the cell can be prevented. In the present invention, the laminated sealing material for solar cells has a resin film, so that the moisture permeability is easily lowered.

[Method for producing solar cell sealing material and solar cell laminated sealing material]
The solar cell sealing material of the present invention is preferably obtained by curing a sealing material composition containing at least a urethane resin raw material and a plurality of particles having a hollow portion therein. At this time, a plurality of unfoamed expandable particles (expandable particles) such as expandable microcapsules are preliminarily heated and expanded into a plurality of expanded particles, and the expanded particles are mixed with a urethane resin raw material to form a sealing material. It is preferred to obtain a composition.
Here, the expandable particles such as expandable microcapsules may be preliminarily heated and expanded alone without being mixed with other components. Further, a part of the urethane resin raw material, preferably a part of the polyol component, is mixed with a plurality of unfoamed particles having foamability, and the mixture is heated in advance to expand the foamable particles to foam. Then, the remaining urethane resin raw material (preferably, the remainder of the polyol component and the isocyanate compound) may be further mixed with the mixture to obtain a sealing material composition. At this time, materials other than the urethane resin raw material and particles may be appropriately blended at any timing.
As described above, when the foamable particles are expanded in advance before molding and curing, the bubble diameter can be easily controlled and the sealing performance can be easily improved.

  However, in this invention, you may harden the sealing material composition containing the particle | grains which have the foamability before foaming. In this case, the foamable particles are blended in the sealing material composition in an unexpanded state, and when the sealing material composition is heat-cured, it is thermally expanded simultaneously with the heating to form a cavity inside, It becomes foamed particles. Moreover, the sealing material composition may contain both expanded particles that have been heated and expanded in advance and unexpanded (unexpanded) expandable particles. The unfoamed and expandable particles may be expanded at the time of curing or may not be expanded.

In the present invention, the sealing material composition has a thickness that the sealing material has (for example, a thickness of 0.05 mm or more and 2.mm) by a press method, a roll transfer method, a roll cast method, a die cast method, a die extrusion method, or the like. 5 mm or less), and it is preferably cured in that state to form a solar cell sealing material.
Thus, in the manufacturing method of this invention, the process of shape | molding a sealing material composition and hardening the sheet | seat is performed collectively. And what was obtained by the hardening becomes the above-mentioned thin sealing material (for example, thickness 0.05 mm or more and 2.5 mm or less). That is, the solar cell sealing material obtained by this manufacturing method is not obtained by, for example, slicing a thick sealing material in parallel to the main plane, and thus stably manufacturing a sealing material having high sealing performance. Is possible.
Moreover, the sealing material for solar cells is a slab molding method obtained by curing urethane resin (A) under normal temperature and atmospheric pressure, or a sealing material composition is injected into a molding die, and the mold is clamped and cured in the die. It may be manufactured by a molding method obtained in this way. In this case, the slab molding method is preferable because it is simpler and can be continuously produced.

In the present invention, the sealing material composition is preferably cured by heating, and the heating temperature at the time of curing is not limited as long as the urethane resin raw material can be cured, but less than the melting temperature of the outer shell of the particles (B). In addition, when the particle (B) has already expanded, the temperature is preferably lower than the temperature at which the particle was expanded. Thereby, it is prevented that the shape and particle diameter of particle | grains (B) change with the heating at the time of hardening. The specific heating temperature is, for example, 80 to 180 ° C, preferably 100 to 160 ° C.
Regarding the reaction method of the urethane resin (A), a one-shot method in which a polyol component such as polyether polyol and an isocyanate compound other than the prepolymer are directly reacted, or the polyol component and the isocyanate compound are reacted in advance to terminate the reaction. Any prepolymer method in which a prepolymer having an isocyanate group is obtained and a polyol component is allowed to react with the prepolymer is employed.

  Moreover, the laminated sealing material for solar cells of the present invention is obtained by superposing a sealing material composition and a resin film in the same manner as described above, and then curing the sealing material composition, and the resin film is obtained by this curing. It is preferable to adhere to the sealing material. Curing is preferably performed by heating at the heating temperature described above. As a method for increasing the adhesive strength between the sealing material and the film (B), a method in which a coupling agent is previously added to either or both of the sealing material composition and the resin film, and the bonding between the sealing material composition and the resin film. A method of applying a primer such as a coupling agent to the surface, a method of disposing an adhesive on the bonding surface of the sealing material composition and the resin film, as long as the thickness and properties of the sealing material composition and the resin film are not impaired. Can be mentioned.

[Solar cell module]
The solar cell sealing material of the present invention is preferably used for solar cell panel applications. Also when used for solar cell panels, the solar cell sealing material may be used as a single sealing material as described above, but is provided with another layer on one or both sides of the sealing material. It may be.

  2 and 3 show a solar cell module using the solar cell sealing material of the present invention. As shown in FIGS. 2 and 3, the solar cell module 20 includes a solar cell panel 21, a frame 22 as a fixing member that fixes the peripheral end 21 </ b> C of the solar cell panel 21, and between the peripheral end 21 </ b> C and the frame 22. The laminated sealing material 10 for solar cells, which is disposed in 2 and 3 show an example in which the solar cell laminated sealing material 10 in which the resin film 13 is laminated on one surface of the sealing material 11 is used. However, if the solar cell sealing material is used, FIG. Instead of the laminated sealing material 10 for solar cells, a material having another configuration such as a single sealing material for solar cells may be used.

  The solar cell panel 21 has a substantially rectangular flat plate shape, and a known solar cell panel such as a crystal system, a thin film system, and a CI (G) S system is used. The solar cell panel 21 is sequentially formed on a power generation layer, both surfaces thereof, that is, a glass substrate (not shown) formed on a light receiving side surface 21A that receives sunlight, and a back surface (a side surface opposite to the light receiving side surface) 21B. It is comprised from the resin layer (not shown) and the protective layer (not shown). Although not shown, the solar cell panel 21 has a terminal cable (not shown) for taking out electricity from the power generation layer and a terminal box (not shown) for housing the terminal cable on the back surface 21B. Is provided. The thickness of the solar cell panel 21 is, for example, 2 to 10 mm, preferably 3 to 6 mm.

  As shown in FIGS. 2 and 3, the frame 22 is provided along each side of the solar cell panel 21. The frame 22 is formed in a substantially U-shaped cross section that opens inward, and includes a flat side wall 23, a flat light-receiving surface side wall 24 that extends inward from the top of the side wall 23, and a lower part of the side wall 23. And a flat plate-like back side wall 25 extending inward from the inside. The frame 22 is made of, for example, a metal material such as aluminum or a resin material, and is preferably made of aluminum. The frame 22 is assembled so that the ends in the longitudinal direction along each side of the solar cell panel 21 are joined together to form four corners and form a frame shape in plan view.

  The laminated sealing material 10 for solar cells is bent into a substantially U-shaped cross-section in contact with the side surface 21D, the light receiving side surface 21A and the back surface 21B of the panel 21 at the peripheral end 21C of each side of the solar cell panel 21. And the laminated sealing material 10 for solar cells of the solar cell panel 21 so that the surface (seal material itself) opposite to the surface on which the resin film 13 is provided is in contact with each surface of the peripheral end portion 21C. It is closely attached to the peripheral end 21C and attached to the peripheral end 21C. And the resin film 13 is arrange | positioned in the outer side (frame 22 side) in the laminated sealing material 10 for solar cells made into U shape, and the sealing material 11 for solar cells is the inside (solar cell panel). 21 side). The inner side of the laminated sealing material 10 for solar cells may be light-guided through the glass or resin of the solar cell panel 21 and indirectly irradiated with sunlight, but a seal formed from a urethane resin having excellent light resistance. Since the material 11 is on the inner side, the resin film 13 is prevented from being deteriorated by sunlight, and the durability of the solar cell laminated sealing material 10 is improved. Moreover, when the laminated sealing material 10 for solar cells is attached around the peripheral end 21C of each side of the solar cell panel 21 and returns to the attachment start position, the portions are overlapped. By overlapping in this way, it is possible to prevent water (including water vapor) from entering between the end portions of the solar cell sealing material 10. The overlapped portion has a doubled substantial thickness.

  The peripheral end portion 21 </ b> C to which the solar cell sealing material 10 is attached is press-fitted into the U shape of the frame 22 and attached to the frame 22. Thereby, the frame 22 supports the solar cell panel 21 by further sandwiching the peripheral end portion 21 </ b> C of the solar cell panel 21 sandwiched by the solar cell sealing material 10. The solar cell sealing material 10 is compressed and disposed between the light receiving side surface 21A and the light receiving surface side wall 24, between the side surface side wall 23 and the side surface 21D, and between the back surface 21B and the back surface side wall 25. Is sealed. At this time, it is preferable to arrange | position the laminated sealing material 10 for solar cells in the state compressed by 20 to 50% of compression rates under 20 degreeC. Due to individual differences between the solar cell panel and the frame, there is usually a variation in the size of the gap between the panel 21 and the frame 22. In the present invention, the compression stress and the foaming ratio of the sealing material 11 are within the above-described range, and the compression rate is within this range, so that even if the gap size varies, the solar cell laminated sealing material 10 is used for the solar cell. The gap between the battery panel 21 and the frame 22 can be sufficiently filled. In addition, when the compressibility is within the above range, moisture can be prevented from entering between the peripheral edge portion 21C of the solar cell panel 21 and the frame 22 during cleaning using wind and rain or a cleaning machine. Moreover, the efficiency of the operation | work which fits the solar cell panel 21 in the flame | frame 22 becomes good because a compression rate shall be 50% or less.

  As described above, the solar cell sealing material 10 seals the peripheral end portion 21 </ b> C of the solar cell panel 21, and prevents water from entering the solar cell panel 21, for example. In the present invention, the sealing material 11 is a urethane resin in which a plurality of particles having cavities are dispersed. Therefore, the waterproof performance and shock absorption performance of the solar cell sealing material 10 are high. .

  In the present invention, since the sealing material for solar cells uses a sealing material in which a plurality of particles having hollow portions are dispersed in urethane resin, even if no adhesive layer is provided, the space between the frame 22 and the solar cell panel 21 is used. The sealing performance is sufficiently secured.

  The present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[Measuring method]
Each physical property and performance was evaluated by the following methods.
[Average particle size and porosity]
Calculation was performed by a method described in the specification using a microscope (manufactured by Keyence Corporation, model VH-Z series).
[Thickness]
Measured with a dial gauge.
[Specific gravity and foaming ratio of sealing material]
The specific gravity of the sealing material was measured according to JIS K6767. The expansion ratio is obtained by dividing the specific gravity of the sealing material composition by the specific gravity of the solar cell sealing material. However, the sealing material composition at this time is in a state before the particles (B) expand.
[Compressive stress]
In accordance with JIS K6767, the 20% compressive stress of the solar cell sealing material was measured. In the present invention, the measurement was performed by stacking a plurality of solar cell sealing materials so that the total thickness was 10 mm.
[Closed cell ratio]
This was performed by the method described in the specification.

[Compression set]
The compression set of the solar cell sealing material or solar cell laminated sealing material was measured according to JIS K 6767. In the present invention, a plurality of solar cell sealing materials or solar cell laminated sealing materials are stacked so that the total thickness becomes 10 mm, and the temperature is set to 70 ° C., the compression rate is set to 50%, that is, the thickness is reduced to 5 mm. The measurement was performed in accordance with JIS except for the above.

[Example 1]
[Production of Particle (B)]
7 parts by mass of thermally expandable microcapsules and 70 parts by mass of polyether polyol were mixed to obtain a uniform mixture. Next, the mixture was placed on a PET film and heated at 155 ° C. for 4 minutes to expand the thermally expandable microcapsules, thereby obtaining a mixture containing particles (B) having cavities inside.

  Next, 77 parts by mass of the mixture containing the particles (B) obtained above, 30 parts by mass of a polyether polyol, 45 parts by mass of an isocyanate compound, 0.1 part by mass of an amine catalyst, 2 parts by mass of a phosphorus-based antioxidant, a hindered amine 0.8 parts by mass of a light stabilizer and 1.0 part by weight of a benzotriazole ultraviolet absorber were mixed at room temperature (23 ° C.) to obtain a sealing material composition. The details of each raw material of the sealing material composition are shown below, and the formulation is shown in Table 1. In addition, the ratio of the thermally expansible microcapsule in all the raw materials of a sealing material composition was 4.5 mass%.

Polyether polyol: Polyoxypropylene glyceryl ether (“Sanix GP-3000” manufactured by Sanyo Chemical Industries, Ltd., functional group number 3, OHV = 56, number average molecular weight 3000)
Thermally expandable microcapsules: “Advancel EML-101” manufactured by Sekisui Chemical Co., Ltd., average particle size 16 μm, spherical, expansion start temperature 122 ° C., maximum expansion temperature 167 ° C.
Isocyanate compound: TDI (Nippon Polyurethane Industry Co., Ltd. “Coronate T-65”)
Amine catalyst: Pentamethyldiethylenetriamine (manufactured by Kao Corporation, “Caorizer No. 3”)
Phosphorus antioxidant: Tris (2-ethylhexyl) phosphite (“JP-308E” manufactured by Johoku Chemical Industry Co., Ltd.)
Hindered amine light stabilizer: a mixture of bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (BASF) “TINUVIN 765”
Benzotriazole ultraviolet absorber: 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol ("TINUVIN 571" manufactured by BASF)

[Production of sealing material]
The sealing material composition is quantitatively continuously supplied between two rolls having a clearance of 0.6 mm, and spread between two release PET films (Toray Film Processing, Therapy BLK, thickness 0.05 mm). And heated at 70 ° C. for 3 minutes. Then, after leaving at room temperature (23 degreeC) for 1 day, any release PET film was peeled off and the solar cell sealing material was obtained. When the thickness and specific gravity were measured, they were 0.5 mm and 0.18 g / cc, respectively. In the sealing material, the average particle diameter of the particles (B) was 80 μm, which was 5 times that of the thermally expandable microcapsules before foaming. Further, the porosity of the particles (B) was 92%. Furthermore, the expansion ratio of the solar cell sealing material was 5 times.

[Comparative Example 1]
As a sealing material of Comparative Example 1, a urethane foam “Color Foam EFS” (manufactured by INOAC) having a thickness of 5 mm was used.

Table 2 shows the evaluation results of the sealing materials of Examples and Comparative Examples.

  The sealing material of Example 1 was satisfactory in various test results and could be sufficiently used as a solar cell sealing material. Although the sealing material of Comparative Example 1 has good compression set, it is considered that the sealing property is low due to insufficient compression stress. For this reason, when used in solar cell panel applications, it is estimated that water vapor permeates into the solar cell panel, and is not suitable as a sealing material for solar cell panels.

DESCRIPTION OF SYMBOLS 10 Laminated sealing material 11 for solar cells Seal material 13 Resin film 20 Solar cell module 21 Solar cell panel (attachment body)
22 Frame (fixing member)

Claims (12)

  A solar cell sealing material comprising a urethane resin (A) and a plurality of particles (B) dispersed in the urethane resin (A) and having a hollow portion therein.   The solar cell sealing material according to claim 1, wherein the plurality of particles (B) include expanded foam particles, and an average particle diameter is 40 to 200 μm.   The sealing material for solar cells according to claim 1 or 2, wherein the urethane resin (A) is a polyether-based urethane.   The solar cell according to any one of claims 1 to 3, wherein the solar cell sealing material is obtained by curing a sealing material composition, and the sealing material composition includes at least a hindered amine light stabilizer. Sealing material.   The solar cell sealing material is obtained by curing a sealing material composition, and the sealing material composition contains at least an ultraviolet absorber composed of a benzotriazole-based compound. The sealing material for solar cells as described.   The solar cell sealing material according to claim 1, which has a closed cell ratio of 70% or more and a 20% compressive stress at 20 ° C. of 0.05 to 0.7 MPa.   A laminated sealing material for solar cells, comprising the solar cell sealing material according to any one of claims 1 to 6 and a resin film laminated on one surface of the solar cell sealing material.   The solar cell seal according to any one of claims 1 to 7, which is disposed between the solar cell panel, a fixing member that fixes a peripheral end of the solar cell panel, and the fixing member and the solar cell panel. A solar cell module comprising a material or a laminated sealing material for solar cells.   A solar cell sealing material obtained by curing a sealing material composition including a urethane resin raw material and a plurality of particles having a hollow portion therein to form bubbles by forming air bubbles in the particle hollow portion. Manufacturing method.   A plurality of foamable particles are heated and foamed to obtain a plurality of foamed particles having cavities therein, and the foamed particles and a urethane resin raw material are mixed to obtain the sealing material composition. The manufacturing method of the sealing material for solar cell panels of description.   After mixing a part of the polyol component of the urethane resin raw material and a plurality of expandable particles, the expandable particles are heated and expanded to form expanded particles having a cavity therein, and a plurality of expanded particles A step of obtaining a mixture containing a part of the polyol component, a step of obtaining at least a remainder of the polyol component of the urethane resin raw material and an isocyanate compound in the mixture to obtain a sealing material composition, and heating the sealing material composition The manufacturing method of the sealing material for solar cell panels of Claim 9 or 10 including the process of making it harden | cure and obtaining the said sealing material for solar cells.   For solar cells in which a sealing material composition containing a urethane resin raw material and a plurality of particles having cavities inside is cured in a state of being superimposed on a resin film, and bubbles are formed by the cavities of the particles The manufacturing method of the laminated sealing material for solar cells which obtains the laminated sealing material for solar cells by which the said resin film was laminated | stacked on the single side | surface of the sealing material.

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