JP2010221673A - Resin seal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin seal sheet which is excellent in blocking resistance and easy to be aligned when laminated. <P>SOLUTION: The resin seal sheet (1) has light-transmitting parts (14 and 16) and embossed parts (12) formed around the light-transmitting parts (14 and 16) and composed of protrusions and recesses. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin sealing sheet.

  In recent years, the global warming phenomenon has heightened awareness of the environment, and a new energy system that does not generate greenhouse gases such as carbon dioxide is attracting attention. Since the energy generated by solar cell power generation does not emit carbon dioxide and other gases that cause global warming, research and development has been conducted as clean energy, and has attracted attention as industrial energy. Representative examples of solar cells include those using single crystal and polycrystalline silicon cells (crystalline silicon cells), those using amorphous silicon, and compound semiconductors (thin film cells). Solar cells are often used outdoors for a long period of time by being exposed to wind and rain, and the power generation part is modularized by laminating a glass plate or back sheet to prevent moisture from entering from outside. It was intended to protect and prevent leakage. The member that protects the power generation portion uses transparent glass or transparent resin on the light incident side in order to ensure light transmission necessary for power generation. For the member on the opposite side, an aluminum foil called a back sheet, a polyvinyl fluoride resin (PVF), polyethylene terephthalate (PET), or a laminated sheet of a barrier coating such as silica is used. The power generation element is sandwiched between resin sealing sheets, the outside is further covered with glass or a back sheet, heat treatment is performed to melt the resin sealing sheet, and the whole is integrally sealed (modularized).

  The following (1) to (3) are required as characteristics of the resin-encapsulated sheet described above. (1) Good adhesion to glass, power generation element and back sheet, (2) Flow prevention (creep resistance) of power generation element due to melting of resin-sealed sheet at high temperature, (3) Transparency that does not hinder the incidence of sunlight. From this point of view, the resin-encapsulated sheet is made of an ethylene-vinyl acetate copolymer (hereinafter also abbreviated as EVA), an ultraviolet absorber as a measure against ultraviolet deterioration, a coupling agent for improving adhesion to glass, For crosslinking, additives such as organic peroxides are blended, and the film is formed by calendar molding or T-die casting. In view of exposure to sunlight over a long period of time, various additives such as a light-resistant agent are blended in order to prevent deterioration of optical properties due to deterioration of the resin. Thereby, the transparency which does not inhibit the incidence of sunlight for a long time is maintained.

  As a form of modularizing solar cells with the resin-encapsulated sheet as described above, glass / resin encapsulated sheet / power generation element such as crystalline silicon cell / resin encapsulated sheet / back sheet are stacked in this order, and the glass surface is Using a dedicated solar cell vacuum laminator, the resin encapsulated sheet is melted and pasted through a preheating step and a pressing step above the melting temperature of the resin (150 ° C in the case of EVA) There is. In this method, first, the resin of the resin sealing sheet is melted in the preheating process, and is in close contact with the member in contact with the melted resin in the pressing process and vacuum laminated. In this laminating step, (i) a crosslinking agent contained in the resin sealing sheet, for example, an organic peroxide, is thermally decomposed to promote EVA crosslinking. (Ii) It is covalently bonded to the member in contact with the coupling agent contained in the resin sealing sheet. Thereby, mutual adhesiveness improves more and the outstanding adhesiveness with glass, a power generation element, and a back sheet is implement | achieved.

  Moreover, in order to improve the blocking resistance at the time of vacuum lamination, the embossed sheet which embossed the surface of the sheet is used as a resin sealing sheet. By embossing, unevenness due to embossing is formed on the surface of the sheet, so that blocking during vacuum lamination can be prevented.

Patent Document 1 discloses a solar cell filling adhesive sheet made of an ethylene copolymer resin containing a coupling agent and an organic peroxide.
Patent Document 2 discloses a sheet for sealing a solar cell, which is a sheet made of an ethylene vinyl acetate copolymer blended with a crosslinking agent and a silane coupling agent, and is radiation-crosslinked to a certain gel fraction. Is disclosed.
In the above document, after stacking each member such as glass, sealing sheet, cell, back sheet, etc., a solar cell module is manufactured by performing melt bonding and cross-linking with an organic peroxide using a vacuum laminator. ing.

JP 58-060579 A JP-A-8-283696

  However, the resin-encapsulated sheet subjected to the embossing has a problem that the visibility of the sheet is poor because reflection of light can occur due to the unevenness formed by the embossing. Since the embossed resin sealing sheet cannot be visually recognized from the front surface of the sheet, it is difficult to accurately position (stack) the resin sealing sheet and the back sheet together. This problem is particularly noticeable when used as a sealing material for solar cells.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a resin-encapsulated sheet that is excellent in blocking resistance and that can be easily aligned during lamination.

  As a result of earnest studies on the above problems, the present inventors have found that a solar cell module sealed with a resin sealing sheet whose gel fraction is adjusted to a specific range can solve the above problems. The headline and the present invention were completed.

That is, the present invention provides the following.
[1]
A light transmission part;
An embossed part formed of a convex part and a concave part formed around the light transmitting part,
A resin-encapsulated sheet.
[2]
The resin-encapsulated sheet according to [1], wherein the light transmitting portion has a haze value of 30% or less.
[3]
The resin-sealed sheet according to [1] or [2], wherein the light transmission part is a flat surface.
[4]
The resin transparent sheet according to any one of [1] to [3], wherein the light transmission part is formed in a substantially rectangular shape or geometric shape.
[5]
The resin sealing sheet according to any one of [1] to [4], wherein the minimum value of the width of the light transmission part is 3 mm or more and 30 mm or less.
[6]
The resin sealing sheet according to any one of [1] to [5], wherein a minimum thickness of the light transmission part is 90% or less of a thickness of the convex part of the embossed part.
[7]
Formed by extrusion,
The resin-encapsulated sheet according to any one of [1] to [6], wherein the light transmission part is formed at an inclination of 15 degrees or more with respect to a flow direction of the sheet at the time of extrusion molding.

  According to the present invention, it is possible to provide a resin-encapsulated sheet that is excellent in blocking resistance and that can be easily aligned during lamination.

It is a front view of one embodiment of the resin sealing sheet of the present embodiment. It is the enlarged view which looked at the area | region A in the resin sealing sheet of FIG. It is a front view of another one Embodiment of the resin sealing sheet of this Embodiment. It is a front view of another one Embodiment of the resin sealing sheet of this Embodiment. It is a front view of other one Embodiment of the resin sealing sheet of this Embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The resin sealing sheet according to the present embodiment is a resin sealing sheet having a light transmitting part and an embossed part formed of a convex part and a concave part around the light transmitting part.

  FIG. 1 is a front view of an embodiment of the resin sealing sheet of the present embodiment, and FIG. 2 is an enlarged view of a region A in the resin sealing sheet of FIG. As shown in FIG. 1, the resin sealing sheet 1 of the present embodiment has an embossed part 12 and light transmitting parts 14 and 16. The embossed portion 12 is formed around the light transmitting portions 14 and 16. As shown in FIG. 2, the embossed part 12 has a convex part 12a and a concave part 12b. Accordingly, the light is reflected by the embossed portion 12 in the uneven shape due to the embossing, so that the back surface may not be visually recognized from the sheet surface, but the light transmissive portions 14 and 16 can visually recognize the back surface from the sheet surface.

  Here, “embossing” means forming a concavo-convex shape on the sheet surface by physical or chemical action. For example, a method in which a resin sheet is sandwiched between a relief plate and an intaglio plate and pressed to lift the surface of the sheet, and the like. The “periphery” may be that the embossed part may be surrounded by the light transmitting part or may not be surrounded.

  The shape and size of the embossed portion of the embossed part are not particularly limited, and suitable conditions can be selected based on the use of the resin sealing sheet. The shape (pattern) of the emboss is not particularly limited, and examples thereof include stripes, textures, pearskins, skin patterns, diamond lattices, synthetic leather-like wrinkle patterns, pyramid patterns (quadratic pyramids), and the like. The embossed portion preferably has a small number of flat portions, and the ratio of the area of the convex portion due to embossing in the entire area of the embossed portion is more preferably 5 to 50%.

  The embossing part may be embossed on at least one side of the resin encapsulating sheet, but may be embossed on both sides of the resin encapsulating sheet. From the viewpoint of the anti-blocking performance of the resin sealing sheet, the embossing depth is preferably 10 μm or more, more preferably 15 μm or more.

  The light-transmitting part of the resin-encapsulated sheet is not particularly limited as long as it can transmit light, and the haze value is preferably 30% or less. It is more preferably 25% or less, and further preferably 20% or less. By setting the haze value to the above numerical value, the object to be sealed sealed with the resin sealing sheet can be confirmed in appearance, and at the same time, when used as a solar cell sealing material, the resin sealing sheet and the back sheet, etc. Positioning (stacking) when sticking together becomes easy. And when it is set as a solar cell, practically sufficient electric power generation efficiency is obtained. Here, the haze value can be measured according to ASTM D-1003.

  The light transmission part may be colored according to the use of the sealing resin sheet as long as light transmission is possible. For example, the entire resin sealing sheet may be colored in the same color, or the light transmission part and the embossed part may be colored in different colors. From the viewpoint of obtaining good visibility, the light transmission part is preferably transparent.

  The shape of the light transmission part is not particularly limited, and can be a suitable shape based on the use of the resin sealing sheet. The light transmission part is preferably a recess located on the sheet surface. Furthermore, the light transmission part is more preferably a flat surface. By making the light transmissive part a flat surface, reflection of light can be suppressed and light can be transmitted in the light transmissive part, and thus visibility in the light transmissive part can be improved.

  The thickness of the light transmission part is smaller than the maximum thickness of the convex part of the embossed part and thicker than the minimum thickness of the bottom part of the concave part of the embossed part. For example, at the time of embossing, the light transmission part can be formed on the sheet by not forming the unevenness of the embossing in a desired region on the sheet surface.

  The thickness of the light transmission part will be specifically described with reference to FIG. In the figure, Y is an embossed part, and X is a light transmitting part. The thickness H of the light transmission part 14 is smaller than the thickness Ha of the convex part 12a of the embossed part, and thicker than the thickness Hb of the concave part 12b of the embossed part (Hb <H <Ha). The light transmission part 14 has good visibility because the embossed irregularities are not formed. Therefore, alignment with another member can be easily performed by providing the light transmission part 14 in a resin sealing sheet.

  The minimum value of the thickness of the light transmitting portion is preferably 90% or less, more preferably 85% or less, and further preferably 82% or less of the thickness of the convex portion 12a of the embossed portion. Since the minimum value of the thickness of the light transmission part is the above-mentioned ratio, blocking can be suppressed because the convex part 12a of the embossed part makes point contact with the back sheet or the like. Further, since the light transmitting portion is a flat surface, the visibility is improved, and the alignment with the back sheet or the like can be easily performed.

  The shape of the light transmission part is not particularly limited, but can be a substantially rectangular shape, geometric shape, design figure, character, or other various patterns, for example, a circular shape, a square shape, a polygonal shape, a star shape , Etc. Among them, a substantially rectangular shape or a geometric shape is preferable. Here, the “substantially rectangular shape or geometric shape” includes a rectangle or a shape obtained by deforming the geometric shape, and examples thereof include a rectangle, a rhombus, a parallelogram, a trapezoid, and other geometric shapes. By making the light transmission part substantially rectangular or geometrical, the visibility in the light transmission part tends to be improved.

The shape of the light transmission part will be specifically described with reference to FIGS.
As shown in FIG. 3, the resin sealing sheet 2 includes an embossed portion 22 and a light transmitting portion 24 that is formed in a substantially rectangular shape along the flow direction (MD direction) F of the sheet. There may be. Here, the “sheet flow direction (MD) direction” indicates an extrusion direction when the sheet is formed into a sheet shape.

  It is preferable that the minimum value L of the width | variety of a light transmissive part is 3-30 mm. More preferably, it is 4-27 mm, More preferably, it is 5-25 mm. By making the minimum value of the width | variety of a light transmissive part into the said numerical value, visibility is favorable and blocking can be suppressed effectively. From the viewpoint of securing a minimum visual field and suppressing blocking, it is preferable that the minimum value of the width of the light transmitting portion is in the above range.

  As shown in FIG. 4, even if the resin sealing sheet 3 includes an embossed portion 32 and a substantially rectangular light transmitting portion 34 formed obliquely with respect to the flow direction F of the sheet. Good. In this case, it is preferable that the light transmission part 34 is formed to be inclined by 15 degrees or more with respect to the flow direction (MD direction) F of the sheet. Since the light transmission part 34 is inclined by 15 degrees or more, the alignment in the width direction can be easily performed when the light transmission part 34 is attached to the back sheet or the like. And as shown in FIG. 1, it is more preferable to incline 15 degree | times or more and to form in mesh shape.

  As shown in FIG. 5, the resin sealing sheet 4 has an embossed portion 42, a circular light transmitting portion 44, a square light transmitting portion 46, and a polygonal light transmitting portion 48. It may be. Thus, the shape of the light transmission part in a resin sealing sheet does not necessarily need to be the same, and may differ.

  The ratio of the light transmitting portion in the entire sheet is not particularly limited, but the ratio of the area of the light transmitting portion per unit area of the resin-sealed sheet when viewed from the front may be small. Even if the ratio of the area of the light transmission part per unit area of the resin sealing sheet is small, good visibility and blocking resistance can be ensured.

  When the resin encapsulating sheet is used as a solar cell encapsulant, in order to ensure practically sufficient power generation efficiency, the total light transmittance of the entire resin encapsulating sheet is preferably 85% or more, It is more preferably 87% or more, and further preferably 88% or more. Here, the total light transmittance can be measured in accordance with ASTM D-1003.

  The resin sealing sheet of the present embodiment is preferably subjected to a crosslinking treatment. By crosslinking, when sealing an object to be sealed (solar cell or the like), creep resistance and gap filling property tend to be better. As a method for crosslinking the resin-encapsulated sheet, a known method can be used without limitation, and examples thereof include ionizing radiation (electron beam, γ-ray, ultraviolet ray, etc.) irradiation and crosslinking treatment by crosslinking treatment with organic peroxide. It is done.

  The resin-encapsulated sheet is “crosslinked” means that the gel fraction is preferably 1% by mass or more as a result of physically and chemically crosslinking the polymer constituting the resin by a known method. Say. For example, when sealing an object to be sealed such as a solar battery cell using two resin sealing sheets having the same component, the gel fraction of the resin sealing sheet is preferably 1 to 90% by mass, more preferably It is 2-85 mass%, More preferably, it is 2-65 mass%. For example, when using a resin sealing sheet having different components, one resin sealing sheet may be uncrosslinked, and the gel fraction of the other resin sealing sheet may be 90% by mass or less.

  When the gel fraction is 1% by mass or more, the heat resistance tends to be improved, and when it is 65% by mass or less, the sealing property (sealing property) to the object to be sealed tends to be good. In addition, even if it is a case where the resin sealing sheet has either a single layer structure or a multilayer structure described later, the gel fraction is the average gel fraction of the entire resin sealing sheet (total layer gel fraction). ) Value. As a means for adjusting the gel fraction of the resin-encapsulated sheet to the above range, a suitable crosslinking treatment can be given to the sheet.

The gel fraction of the resin sealing sheet can be obtained by the following formula from the ratio of the insoluble portion after extracting the resin sealing sheet in boiling p-xylene for 12 hours.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

  In the case of crosslinking by ionizing radiation, the thickness reduction rate can be adjusted by irradiation intensity (acceleration voltage) and irradiation density. The irradiation intensity (acceleration voltage) indicates how deep electrons can reach in the thickness direction of the sheet, and the irradiation density indicates how many electrons are irradiated per unit area. In the case of crosslinking with an organic peroxide, the thickness reduction rate can be adjusted by the content of the organic peroxide. Moreover, you may utilize the effect of the bridge | crosslinking acceleration | stimulation or bridge | crosslinking suppression by the difference in the bridge | crosslinking degree by the kind of resin, or a transfer agent.

  In the case of crosslinking by irradiation with ionizing radiation, a method of irradiating the resin encapsulating sheet with ionizing radiation such as α-ray, β-ray, γ-ray, neutron beam, electron beam, etc. to cross-link can be mentioned. The acceleration voltage of ionizing radiation such as an electron beam may be selected according to the thickness of the resin sealing sheet. For example, when the thickness is 500 μm, when the entire resin sealing sheet is crosslinked, the acceleration voltage is 300 kV or more. is necessary.

  The acceleration voltage of ionizing radiation such as an electron beam can be appropriately adjusted according to the resin layer subjected to the crosslinking treatment. The irradiation dose of ionizing radiation varies depending on the resin used, but is generally less than 3 kGy. It tends to be difficult to uniformly cross-link the entire resin-encapsulated sheet.

  In the case of crosslinking with an organic peroxide, thermal crosslinking is performed by blending or impregnating the organic peroxide in the resin as a crosslinking agent. In this case, an organic peroxide having a half-life at 100 to 130 ° C. of 1 hour or less is preferable.

  Examples of organic peroxides that have good compatibility and have the above half-life include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1 -Bis (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane and the like. The resin-encapsulated sheet using these organic peroxides can reduce the crosslinking time relatively, and the curing process is an organic material having a half-life at 100 to 130 ° C., which is conventionally used, of 1 hour or more. Compared with the case of using a peroxide, it can be shortened to about half.

  The content of the organic peroxide is preferably 0 to 10% by mass and more preferably 0 to 5% by mass with respect to the resin constituting the resin sealing sheet.

  The resin-encapsulated sheet containing the organic peroxide is softened during lamination, and after the gap is filled, the decomposition and crosslinking of the organic peroxide are promoted, so the resin gel fraction increases. However, it has an advantage that the gap filling property is not hindered.

  As described above, “crosslinking” includes a method of irradiating with ionizing radiation and a method of using an organic peroxide, and a method of crosslinking by irradiation with ionizing radiation is particularly preferable. The crosslinking treatment by irradiation with ionizing radiation does not generate gas due to thermal decomposition of the organic peroxide, and therefore tends to reduce corrosion damage and oil contamination of the vacuum pump. In addition, the crosslinking method using an organic peroxide requires a long curing process for decomposing the organic peroxide in the lamination process and promoting the crosslinking of the resin sealing sheet. Although it is difficult to speed up production, the crosslinking method by irradiation with ionizing radiation is excellent in that it does not require a long-time curing step and can improve the productivity of the solar cell module.

  Although it does not specifically limit as resin which comprises a resin sealing sheet, From a viewpoint of ensuring favorable transparency, a softness | flexibility, the adhesiveness of a to-be-adhered object, and handleability, ethylene-vinyl acetate copolymer, ethylene-fat Ethylene unsaturated carboxylic acid copolymer, ethylene-aliphatic carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, ethylene copolymer containing glycidyl methacrylate It is preferable to contain at least one resin selected from the group consisting of a polymer and a polyolefin resin.

  The ethylene-vinyl acetate copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and vinyl acetate. The ethylene-aliphatic unsaturated carboxylic acid copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters.

  The copolymerization can be performed by a known method such as a high pressure method or a melting method, and a multisite catalyst, a single site catalyst, or the like can be used as a catalyst for the polymerization reaction. Moreover, in the said copolymer, the bond shape of each monomer is not specifically limited, The polymer which has bond shapes, such as a random bond and a block bond, can be used. From the viewpoint of optical properties, the copolymer is preferably a copolymer polymerized by random bonding using a high-pressure method.

  In the ethylene-vinyl acetate copolymer, the ratio of vinyl acetate in all monomers constituting the copolymer is preferably 10 to 40% by mass from the viewpoint of optical properties, adhesiveness, and flexibility. More preferably, it is -35 mass%, and it is still more preferable that it is 15-30 mass%. Further, from the viewpoint of workability of the resin-encapsulated sheet, a melt flow rate value (hereinafter also abbreviated as “MFR”) (190 ° C., 2.16 kg) measured according to JIS-K-7210 is obtained. It is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / min to 30 g / min, and still more preferably 0.8 g / min to 25 g / min.

  Examples of the ethylene-aliphatic unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer (hereinafter also abbreviated as “EAA”) and an ethylene-methacrylic acid copolymer (hereinafter, “EMAA”). Abbreviated as well)). Examples of the ethylene-aliphatic unsaturated carboxylic acid ester copolymer include an ethylene-acrylic acid ester copolymer and an ethylene-methacrylic acid ester copolymer. Here, as acrylic acid ester and methacrylic acid ester, ester with C1-C8 alcohols, such as methanol and ethanol, is used suitably.

  These copolymers may be multi-component copolymers obtained by copolymerizing three or more monomers. Examples of the multi-component copolymer include a copolymer obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated carboxylic acid ester.

  In the ethylene-aliphatic unsaturated carboxylic acid copolymer, the proportion of the aliphatic unsaturated carboxylic acid in all monomers constituting the copolymer is preferably 3 to 35% by mass. Further, MFR (190 ° C., 2.16 kg) is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min, and 0.8 g / 10 min to More preferably, it is 25 g / 10 min.

  Examples of the saponified ethylene-vinyl acetate copolymer include a partially or completely saponified ethylene-vinyl acetate copolymer, and examples of the saponified ethylene-vinyl acetate-acrylic acid ester copolymer include ethylene- Examples thereof include a vinyl acetate-acrylic acid ester copolymer part or a completely saponified product.

  The ratio of the hydroxyl group in each saponified product is preferably 0.1% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass, in the resin constituting the resin sealing sheet. More preferably, it is 0.1 mass%-7 mass%. If the proportion of the hydroxyl group is 0.1% by mass or more, the adhesiveness tends to be good, and if it is 15% by mass or less, the compatibility tends to be good. The risk of clouding can be reduced.

  The ratio of the hydroxyl group was determined based on the olefin-based polymer resin of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and VA% of this resin (vinyl acetate copolymer by NMR measurement). (Polymerization ratio), its saponification degree, and the blending ratio in the resin.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer and the ethylene-vinyl acetate-acrylic acid ester copolymer before saponification is determined from the viewpoint of obtaining good optical properties, adhesiveness, and flexibility. It is preferable that it is 10-40 mass% with respect to the whole union, it is more preferable that it is 13-35 mass%, and it is still more preferable that it is 15-30 mass%. The saponification degree of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer is 10 to 70% from the viewpoint of obtaining good transparency and adhesiveness. Is more preferable, 15 to 65% is more preferable, and 20 to 60% is still more preferable.

  Examples of the saponification method include a method of saponifying an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-acrylic ester copolymer pellet or powder using an alkali catalyst in a lower alcohol such as methanol, toluene, And a method of dissolving a copolymer in advance using a solvent such as xylene and hexane and then saponifying using a small amount of alcohol and an alkali catalyst. Moreover, you may graft-polymerize the monomer containing functional groups other than a hydroxyl group to the saponified copolymer.

  Since each saponified product has a hydroxyl group in the side chain, the adhesiveness is improved as compared with the copolymer before saponification. Moreover, transparency and adhesiveness can be controlled by adjusting the amount of hydroxyl groups (degree of saponification).

  The ethylene copolymer containing glycidyl methacrylate refers to an ethylene copolymer and an ethylene terpolymer with glycidyl methacrylate having an epoxy group as a reaction site. For example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer And an ethylene-glycidyl methacrylate-methyl acrylate copolymer. Since the above compounds have high reactivity of glycidyl methacrylate, they can exhibit stable adhesion, and have a low glass transition temperature and tend to have good flexibility.

  As the polyolefin resin, polyethylene resin, polypropylene resin, and polybutene resin are preferable. Here, the polyethylene resin refers to a homopolymer of ethylene or a copolymer of ethylene and one or more other monomers. The polypropylene resin refers to a homopolymer of propylene or a copolymer of propylene and one or more other monomers.

  Examples of the polyethylene resin include polyethylene and ethylene-α-olefin copolymers.

  Examples of the polyethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (referred to as “VLDPE” and “ULDPE”).

  The ethylene-α-olefin copolymer is preferably a copolymer composed of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms, and includes ethylene and 3 to 12 carbon atoms. More preferred is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, and 1-decene. Examples include dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the ratio (based on preparation monomer) of the alpha olefin in all the monomers which comprise a copolymer is 6-30 mass%. Further, the ethylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  In addition, as the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available. It can be used suitably.

The polyethylene resin can be polymerized using a known catalyst such as a single site catalyst or a multisite catalyst, and is preferably polymerized using a single site catalyst. The above polyethylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated. When a high-density polyethylene-based resin is used, the transparency can be improved by adding a low-density polyethylene-based resin at a ratio of about 30% by mass, for example.

  The polyethylene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.5 g / 10 min to 30 g / 10 min, preferably 0.8 g / 10 min to 30 g / min, from the viewpoint of processability of the resin encapsulated sheet. 10 min is more preferable, and 1.0 g / 10 min to 25 g / 10 min is still more preferable.

  As said polyethylene-type resin, the polyethylene-type copolymer which controlled crystal / amorphous structure (morphology) by nano order can also be used.

  Examples of the polypropylene resin include polypropylene, propylene-α-olefin copolymer, and terpolymer of propylene, ethylene, and α-olefin.

  The propylene-α-olefin copolymer refers to a copolymer composed of at least one selected from propylene and α-olefin. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms, and propylene, ethylene and 4 to 8 carbon atoms. A copolymer comprising at least one selected from α-olefins is more preferable. Examples of the α-olefin having 4 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-pentene. , 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the content rate (charged monomer reference | standard) of ethylene and / or alpha-olefin in all the monomers which comprise the said propylene-alpha-olefin copolymer is 6-30 mass%. Furthermore, the propylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available, and preferably Can be used.

The polypropylene resin can be polymerized using a known catalyst such as a single-site catalyst or a multi-site catalyst, and is preferably polymerized using a single-site catalyst. Also the polypropylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated.

  The polypropylene resin preferably has an MFR (230 ° C., 2.16 kgf) of 0.3 g / 10 min to 15.0 g / 10 min from the viewpoint of processability of the resin-encapsulated sheet, preferably 0.5 g / 10 min. 12 g / 10 min is more preferable, and 0.8 g / 10 min to 10 g / 10 min is still more preferable.

  As the polypropylene resin, a polypropylene copolymer in which the crystal / amorphous structure (morphology) is controlled in nano order can also be used.

  Examples of the polypropylene resin include copolymers of propylene and α-olefins such as ethylene, butene, hexene, and octene, or ternary compounds of propylene, ethylene and α-olefins such as butene, hexene, and octene. A copolymer etc. can be used conveniently. These copolymers may be in any form such as a block copolymer, a random copolymer, etc., preferably a random copolymer of propylene and ethylene, or a random copolymer of propylene, ethylene and butene. is there.

  The polypropylene resin is not limited to a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but may be a resin polymerized with a metallocene catalyst, for example, syndiotactic polypropylene, isotactic polypropylene, etc. it can. Moreover, it is preferable that the ratio (based on preparation monomer) of the propylene in all the monomers which comprise a polypropylene resin is 60-80 mass%. Furthermore, from the viewpoint of excellent heat shrinkability, the propylene content ratio (based on the charged monomer) in all monomers constituting the polypropylene resin is 60 to 80% by mass, and the ethylene content ratio (based on the charged monomer) is 10 to 30. A ternary copolymer having a butene content ratio (based on charged monomers) of 5 to 20% by mass is preferable.

  As the polypropylene resin, a resin obtained by uniformly finely dispersing a rubber component having a high concentration of 50% by mass or less with respect to the total amount of the polypropylene resin can be used.

  When the resin constituting the resin sealing sheet contains the polypropylene resin, properties such as hardness and heat resistance tend to be further improved.

  In addition, since the polybutene resin is particularly excellent in compatibility with the polypropylene resin, the polybutene resin is preferably used in combination with the polypropylene resin for the purpose of adjusting the hardness and waist of the resin sealing sheet. The polybutene resin is crystalline and is a copolymer of butene and at least one selected from ethylene, propylene and an olefin compound having 5 to 8 carbon atoms, and constitutes a polybutene resin. A high molecular weight polybutene resin having a butene content of 70 mol% or more in all monomers can be suitably used.

  The polybutene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min. Moreover, it is preferable that a Vicat softening point is 40-100 degreeC. Here, the Vicat softening point is a value measured according to JIS K7206-1982.

The resin sealing sheet of the present embodiment may have either a single layer structure or a multilayer structure. Hereinafter, each structure will be described.
[Single layer structure]
When the resin encapsulating sheet has a single layer structure, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid is used from the viewpoint of ensuring good transparency, flexibility, adhesion of adherends and handleability. From the group consisting of acid copolymer, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and polyolefin resin A layer made of at least one selected resin is preferable.

  When the resin layer constituting the resin encapsulating sheet contains an ethylene-vinyl acetate copolymer saponified product or an ethylene-vinyl acetate-acrylic acid ester copolymer saponified product as an adhesive resin, the degree of saponification And content can be adjusted suitably and, thereby, adhesiveness with a to-be-sealed thing can be controlled. From the viewpoint of adhesiveness and optical properties, the content of the saponified ethylene-vinyl acetate copolymer and saponified ethylene-vinyl acetate-acrylate copolymer in the resin layer is 3 to 60% by mass. Preferably, it is 3-55 mass%, More preferably, it is 5-50 mass%.

[Multilayer structure]
The resin sealing sheet in the present embodiment may have a multilayer structure of at least two layers including a surface layer and an inner layer laminated on the surface layer. Here, the two layers forming both surfaces of the resin sealing sheet are referred to as “surface layers”, and the other layers are referred to as “inner layers”.

  In the case of having a multilayer structure, a layer containing a saponified ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate-acrylic acid ester copolymer as an adhesive resin is a layer in contact with an object to be sealed ( It is preferably formed as at least one surface layer. The surface layer may be a layer composed only of the saponified product described above. However, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, the saponified product and ethylene-vinyl acetate are used. It consists of a mixed resin with at least one resin selected from the group consisting of a copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. A layer is preferred.

  The layer ratio of the surface layer in contact with the object to be sealed preferably has a thickness of at least 5% with respect to the total thickness of the resin sealing sheet from the viewpoint of ensuring good adhesiveness. When the thickness is 5% or more, the same adhesiveness as in the case of the single layer structure described above tends to be obtained.

  The resin constituting the inner layer is not particularly limited, and any other resin may be used in addition to the resin contained in the surface layer described above. For the purpose of imparting other functions to the inner layer, resin materials, mixtures, additives, and the like can be appropriately selected. For example, for the purpose of newly imparting cushioning properties, a layer containing a thermoplastic resin may be provided as the inner layer.

  Examples of the thermoplastic resin used as the inner layer include polyolefin resins, styrene resins, vinyl chloride resins, polyester resins, polyurethane resins, chlorine ethylene polymer resins, polyamide resins, and the like. Those possessed and those derived from plant-derived materials are also included. Among the above, a hydrogenated block copolymer resin, a propylene copolymer resin, and an ethylene copolymer resin that have good compatibility with the crystalline polypropylene resin and good transparency are preferable, and a hydrogenated block copolymer. A resin and a propylene-based copolymer resin are more preferable.

  As the hydrogenated block copolymer resin, a block copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferable. Examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenyl. Examples thereof include ethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and styrene is particularly preferable. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more.

  As the propylene-based copolymer resin, a copolymer obtained from propylene and ethylene or an α-olefin having 4 to 20 carbon atoms is preferable. The content of the ethylene or α-olefin having 4 to 20 carbon atoms is preferably 6 to 30% by mass. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene and 1-decene. 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like.

  The propylene-based copolymer resin may be polymerized using a multi-site catalyst, a single-site catalyst, or any other catalyst. Further, a propylene-based copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

  The ethylene copolymer resin may be polymerized with any of a multisite catalyst, a single site catalyst, and other catalysts. Further, an ethylene copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

When a polyethylene resin is used as the material for the inner layer, the density of the polyethylene resin is preferably 0.860 to 0.920 g / cm ³ from the viewpoint of obtaining appropriate cushioning properties, and 0.870 to 0.915 g. / Cm ³ is more preferable, and 0.870 to 0.910 g / cm ³ is still more preferable. When a resin layer having a density of 0.920 g / cm ³ or more is formed as a layer (inner layer) that does not contact the object to be sealed, the transparency tends to deteriorate.

  Moreover, the resin sealing sheet may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the center layer so as to be symmetrically arranged with respect to the center layer. As such a resin sealing sheet, for example, a resin sealing sheet composed of two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers, Examples thereof include a resin-encapsulated sheet in which the surface layer is composed of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) are composed of the same component.

  In the resin sealing sheet having the above structure, the film thickness of the surface layer is preferably 5 to 40% with respect to the film thickness of the entire resin sealing sheet, and the film thickness of the base layer is the resin sealing sheet. The film thickness of the inner layer (hereinafter sometimes referred to as “core layer”) sandwiched between the base layers is preferably 50% to 90% with respect to the entire film pressure. It is preferable that it is 5 to 40% with respect to the film thickness.

  Next, the viewpoint of resin-encapsulated sheet processability is examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the resin sealing sheet is preferably 0.5 to 30 g / 10 min from the viewpoint of ensuring good workability, and 0.8 to 30 g / 10 min. It is more preferable that it is 1.0 to 25 g / 10 min. When the resin sealing sheet has a multilayer structure of two or more layers, the MFR of the resin constituting the inner layer (base layer or core layer) is preferably lower than the MFR of the surface layer from the viewpoint of resin sealing sheet processability.

  In the resin-encapsulated sheet in the present embodiment, various additives such as a coupling agent, an antifogging agent, a plasticizer, an antioxidant, a surfactant, a colorant, and an ultraviolet absorber are provided as long as the characteristics are not impaired. Further, an antistatic agent, a crystal nucleating agent, a lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator, and the like may be added.

  A coupling agent may be added to the resin sealing sheet for the purpose of ensuring stable adhesion. The addition amount and type of the coupling agent can be appropriately selected depending on the desired degree of adhesion and the type of adherend. The addition amount of the coupling agent is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass, based on the total mass of the resin layer to which the coupling agent is added. More preferably, the content is 0.05 to 3% by mass. As the kind of the coupling agent, a substance that gives the resin layer good adhesion to a solar battery cell or glass is preferable, and examples thereof include organic silane compounds, organic silane peroxides, and organic titanate compounds. . These coupling agents may be added by a known addition method such as injection and mixing into a resin in an extruder, mixing and introducing into an extruder hopper, masterbatching, mixing and adding. it can. However, when passing through an extruder, the function of the coupling agent may be hindered by heat, pressure, etc. in the extruder, so the amount of addition needs to be adjusted appropriately depending on the type of coupling agent. In addition, the type of the coupling agent may be appropriately selected in consideration of the transparency of the resin-encapsulated sheet and the degree of dispersion, the corrosion on the extruder, and the viewpoint of extrusion stability. Preferred coupling agents include γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4- Ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Examples thereof include those having an unsaturated group or an epoxy group such as aminopropyltrimethoxysilane glycidoxypropyltriethoxysilane.

  Moreover, an ultraviolet absorber, antioxidant, discoloration inhibitor, etc. can be added to a resin sealing sheet. In particular, when it is necessary to maintain transparency and adhesiveness over a long period of time, it is preferable to add an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like. When these additives are added to the resin, the amount added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the resin to be added.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4. , 4′-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like. Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, amine-based, hindered phenol-based, hindered amine-based, and hydrazine-based antioxidants.

  These ultraviolet absorbers, antioxidants, discoloration inhibitors and the like are preferably added in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, in the resin constituting the resin sealing sheet. When added to an ethylene-based resin, adhesiveness can be further imparted by mixing a resin having a silanol group into a master batch. The addition method is not particularly limited, and examples thereof include a method of adding to a molten resin in a liquid state, directly kneading and adding to the target resin layer, and applying after sheeting.

  The resin sealing sheet preferably has a thickness of 50 to 1500 μm, more preferably 100 to 1000 μm, and still more preferably 150 to 800 μm. When the thickness is less than 50 μm, there is a tendency for problems in durability and strength from the viewpoint of structurally poor cushioning properties or workability. On the other hand, when the thickness exceeds 1500 μm, there is a tendency that a problem of reducing productivity and adhesion is caused.

[Method for producing resin-encapsulated sheet]
Although there is no restriction | limiting in particular as a manufacturing method of a resin sealing sheet, For example, the following methods are mentioned. First, the resin is melted by an extruder, the molten resin is extruded from a die, and rapidly cooled and solidified to obtain an original fabric. As the extruder, a T die, an annular die or the like is used. When the resin sealing sheet has a multilayer structure, a multilayer T die method and a multilayer annular (circular) die method are suitable, and the multilayer structure may be formed by other known laminating methods.

  The surface of the original fabric is embossed according to the final form of the resin sealing sheet. For example, when embossing treatment is performed on both sides, between the two heated embossing rolls, when performing single-sided embossing processing, the original fabric is passed between embossing rolls heated only on one side. Embossing treatment can be performed.

  The embossing treatment can be performed by a known method, for example, a method of processing the extruded sheet before cooling, a method of applying preheating to the sheet with an IR heater, a temperature control roll, etc., without using preheating, The method etc. which process by the heated embossing roll are mentioned.

  Further, as post-processing, for example, heat setting for dimensional stabilization, corona processing, plasma processing, lamination with other types of resin sealing sheets, and the like may be performed.

  Depending on each case, it is selected whether the crosslinking treatment for the resin constituting the resin encapsulating sheet, that is, the heat treatment by the use of ionizing radiation irradiation or the use of organic peroxide is performed as a pre-process or a post-process of the embossing process. be able to.

[Use of resin encapsulated sheet]
The resin sealing sheet in the present embodiment is particularly useful as a solar cell sealing material for protecting members such as elements constituting the solar cell. In other words, it not only has excellent blocking resistance and is easy to align at the time of lamination, but also has excellent transparency and creep resistance, and good adhesion to the object to be sealed. Thus, the adhesiveness can be controlled. In addition, it stably exhibits strong adhesion to glass plates constituting solar cells and resin plates such as acrylic and polycarbonate. By using the resin sealing sheet in the present embodiment, various members having irregularities such as the solar cell glass itself, various wirings, and power generation elements can be reliably sealed without gaps.

  Moreover, the resin sealing sheet in the present embodiment can be used as a sealing sheet for solar cells, sealing LED, interlayer film of laminated glass and security glass, etc., plastic and glass, plastic to glass, glass to glass It can also be used for bonding and the like.

  The resin sealing sheet of the present invention has industrial applicability as a sealing material for protecting members such as elements constituting solar cells.

1, 2, 3, 4: Resin sealing sheet 12, 22, 32, 42: Embossed part 12a: Convex part of embossed part 12b: Concave part of embossed part 14, 16, 24, 34, 44, 46, 48: Light transmission part

Claims (7)

A light transmission part;
An embossed part formed of a convex part and a concave part formed around the light transmitting part,
A resin-encapsulated sheet.   The resin-encapsulated sheet according to claim 1, wherein the light transmissive portion has a haze value of 30% or less.   The resin sealing sheet according to claim 1, wherein the light transmission part is a flat surface.   The resin sealing sheet according to any one of claims 1 to 3, wherein the light transmission part is formed in a substantially rectangular shape or geometric shape.   The resin sealing sheet of any one of Claims 1-4 whose minimum value of the width | variety of the said light transmissive part is 3 mm or more and 30 mm or less.   The resin sealing sheet according to any one of claims 1 to 5, wherein a minimum thickness of the light transmission portion is 90% or less of a thickness of the convex portion of the embossed portion. Formed by extrusion,
The resin-encapsulated sheet according to any one of claims 1 to 6, wherein the light transmission portion is formed to be inclined at least 15 degrees with respect to a flow direction of the sheet at the time of extrusion molding.

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