WO2016052133A1

WO2016052133A1 - Layered product

Info

Publication number: WO2016052133A1
Application number: PCT/JP2015/075776
Authority: WO
Inventors: 巽規行; 堀江将人; 千代敏弘
Original assignee: 東レ株式会社
Priority date: 2014-09-29
Filing date: 2015-09-11
Publication date: 2016-04-07
Also published as: JPWO2016052133A1; TW201613763A

Abstract

A layered product characterized by comprising a base layer (layer P1) including, as a main component, a polyester resin having a terminal carboxyl group amount of 25 equivalents or less per ton and a readily bondable layer (layer P2), the layer P2 satisfying the following requirements (1) and (2): (1) to have a polar force γp of 4.8-21.0 mN/m, and (2) to have a difference between the polar force γp and the hydrogen bonding force γh, γp-γh, of 1.0-20.0 mN/m. Layered products produced by conventional methods have had a problem wherein the adhesion to encapsulating materials is so low that separation at the boundary with the encapsulating material or delamination thereof from the readily bondable layer is prone to occur not only during the fabrication of solar cells but also during outdoor use as solar cells. In view of such conventional problem, the present invention provides the layered product which is superior to conventional, readily bondable, layered products in adhesion to encapsulating materials and which is suitable for use as a sheet for protecting the back surfaces of solar cells which retain the adhesion (excellent adhesion retentivity) even when placed outdoors for a long period.

Description

Laminated body

The present invention has excellent adhesion to EVA, which is a sealing material for solar cells, and is suitable as a sheet for protecting the back surface of a solar cell, which maintains adhesion even when placed outdoors for a long period of time (excellent adhesion retention). Related to a laminate.

In recent years, photovoltaic power generation has attracted attention as a semi-permanent and pollution-free next-generation energy source, and solar cells are rapidly spreading. In a solar cell, a power generating element is sealed with a transparent sealing material such as ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as EVA), a transparent substrate such as glass, and a back sheet (for back surface protection). A resin sheet called a “sheet” is bonded together. Sunlight is introduced into the solar cell through the transparent substrate. Sunlight introduced into the solar cell is absorbed by the power generation element, and the absorbed light energy is converted into electrical energy. The converted electric energy is taken out by a lead wire connected to the power generation element and used for various electric devices.

Here, inexpensive and high-performance biaxially stretched polyethylene terephthalate (hereinafter referred to as PET) is widely used for the solar cell back surface protection sheet, and various materials are bonded together by a method such as dry lamination. Thus, studies have been made to impart barrier properties and electrical characteristics. However, polyester resins such as PET have poor adhesion to the sealing material. Therefore, conventionally, it is common to laminate a polyolefin resin sheet excellent in adhesion to a sealing material on a polyester resin such as PET and use the polyolefin resin sheet as a sealing material adhesion surface of a solar cell back surface protection sheet. Met.

Moreover, recently, a laminated polyester sheet (

Patent Documents

1, 2, and 3) that can provide an easy-adhesion layer on the surface of a biaxially stretched polyester film and can be directly bonded to a sealing material has been disclosed. .

JP 2006-152013 A Japanese Patent No. 4803317 JP 2012-69835 A

In the laminated polyester sheets listed in Patent Documents 1 to 3, the easy adhesion layer provided on the surface of the biaxially stretched polyester film (base film) and the sealing material (adherent) such as EVA are bonded. (Base film / adhesive layer / adhered body). However, the laminated polyester sheets described in Patent Documents 1 to 3 have a poor balance of adhesion between the base film and the easy-adhesion layer and between the easy-adhesion layer and the adherend such as EVA. Therefore, when the laminated polyester sheet is used as a sheet for protecting the back surface of a solar battery, not only during processing of the solar battery cell, but also while being used outdoors as a solar battery cell, the base film and the easy adhesion layer, easy adhesion There was a problem that peeling occurred between the layer and the adherend. In addition, the conventional film has a problem that when it is placed outdoors for a long period of time, the adhesion is deteriorated (adhesion retention is poor). In order to solve this problem, in the present invention, in view of the conventional problems, the substrate film and the easy adhesion layer, and the adhesion balance between the easy adhesion layer and the adherend are excellent, and the adhesion is good even when left outdoors for a long time. It aims at providing the laminated body suitable as a sheet | seat for solar cell back surface protections (it was excellent in contact | adherence retainability).

In order to solve the above problems, the present invention has the following configuration. That is, it has a base material layer (P1 layer) and an easy adhesion layer (P2 layer) made of a polyester resin having a terminal carboxyl group amount of 25 equivalents / ton or less, and the P2 layer has the following requirements (1) and ( It is a laminate characterized by satisfying 2).
(1) Polar force γp is 4.8 mN / m or more and 21.0 mN / m or less (2) Difference γp−γh between polar force γp and hydrogen bonding force γh is 1.0 mN / m or more and 20.0 mN / m or less

According to the present invention, compared to a conventional laminate in which an easy-adhesion layer is provided on a polyester film, it has excellent adhesion with EVA, which is a sealing material for solar cells, and has excellent adhesion even when placed outdoors for a long period of time. The laminated body which can be used suitably as a sheet | seat for solar cell back surface protection to maintain (it was excellent in close_contact | adherence retainability) can be provided. Furthermore, a highly durable solar cell can be provided by mounting the laminate.

It is sectional drawing which shows typically an example of a structure of the solar cell back surface protection sheet using the laminated body of this invention, and a solar cell.

The laminate of the present invention has a base material layer (P1 layer) and an easy-adhesion layer (P2 layer) made of a polyester resin having a terminal carboxyl group amount of 25 equivalents / ton or less, and the P2 layer has the following requirements: It is characterized by satisfying (1) and (2).
(1) Polar force γp is 4.8 mN / m or more and 21.0 mN / m or less (2) Difference γp−γh between polar force γp and hydrogen bonding force γh is 1.0 mN / m or more and 20.0 mN / m or less Hereinafter, the laminate of the present invention will be described in detail.

(Base material layer (P1 layer))
The P1 layer of the present invention contains a polyester resin as a main component. Here, the polyester resin as a main constituent means that the polyester resin is contained in an amount exceeding 50% by mass with respect to the resin constituting the P1 layer. Specific examples of the polyester resin constituting the P1 layer include polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, and polylactic acid. The polyester resin used in the present invention includes 1) polycondensation of dicarboxylic acid or an ester-forming derivative thereof (hereinafter collectively referred to as “dicarboxylic acid component”) and a diol component, and 2) carboxylic acid or carboxylic acid in one molecule. It can be obtained by a polycondensation of an acid derivative and a compound having a hydroxyl group, and 1) 2). The polymerization of the polyester resin can be performed by a conventional method.

In 1), as the dicarboxylic acid component, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosandioic acid, pimelic acid, azelaic acid, methylmalonic acid, Aliphatic dicarboxylic acids such as ethylmalonic acid, alicyclic dicarboxylic acids such as adamantane dicarboxylic acid, norbornene dicarboxylic acid, cyclohexane dicarboxylic acid, decalin dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid Acid, 5-sodium Ruhoisofutaru acid, phenyl ene boys carboxylic acid, anthracene dicarboxylic acid, phenanthrene carboxylic acid, 9,9'-bis (4-carboxyphenyl) aromatic dicarboxylic acids such as fluorene acid, or the like its ester derivatives and the like as a typical example. These may be used alone or in combination.

In addition, dicarboxyl obtained by condensing oxyacids such as l-lactide, d-lactide, and hydroxybenzoic acid, and derivatives thereof, or a combination of a plurality of such oxyacids, at least one carboxy terminus of the dicarboxylic acid component described above. Compounds can also be used.

Next, as the diol component, aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, Aromatic diols such as cyclohexanedimethanol, spiroglycol, isosorbide, bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9,9'-bis (4-hydroxyphenyl) fluorene Group diols are typical examples. Moreover, these may be used independently or may be used in multiple types as needed. In addition, a dihydroxy compound formed by condensing a diol with at least one hydroxy terminal of the diol component described above can also be used.

In 2), examples of the compound having a carboxylic acid or a carboxylic acid derivative and a hydroxyl group in one molecule include oxyacids such as l-lactide, d-lactide and hydroxybenzoic acid, and derivatives thereof, oligomers of oxyacids, dicarboxylic acids Examples thereof include those obtained by condensing an oxyacid with one carboxyl group of the acid.

The dicarboxylic acid component and the diol component constituting the polyester resin may be copolymerized by selecting one from the above, or may be copolymerized by selecting a plurality of each. Further, the polyester resin constituting the P1 layer may be a single type or a blend of two or more types of polyester resins.

Furthermore, it is important that the polyester resin constituting the P1 layer of the present invention has a terminal carboxyl group amount of 25 equivalents / ton or less. The term “terminal carboxyl group amount” as used herein refers to a value obtained according to the method of Malice and will be described in detail later.

The amount of terminal carboxyl groups of the polyester resin constituting the P1 layer is preferably 19 equivalents / ton or less, and more preferably 16 equivalents / ton or less. When the amount of terminal carboxyl groups of the polyester resin constituting the P1 layer exceeds 25 equivalents / ton, the moisture and heat resistance of the P1 layer is lowered, and when it is placed outdoors for a long period of time, before the adherend and the easy adhesion layer peel off. The laminated body is destroyed due to the deterioration inside the P1 layer, and as a result, the problem that the adhesiveness is lowered occurs.

On the other hand, the lower limit of the amount of terminal carboxyl groups of the polyester resin constituting the P1 layer is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 1 equivalent / ton or more, and 13 amounts / ton. The above is more preferable. When the amount of terminal carboxyl groups in the polyester resin constituting the P1 layer is less than 1 equivalent / ton, the laminate may be excellent in moisture and heat resistance but may be insufficient in adhesion to the easy adhesion layer.

</ RTI> By setting the terminal carboxyl group amount of the polyester resin constituting the P1 layer of the present invention to 25 equivalents / ton or less, it is possible to obtain a laminate having both excellent heat and moisture resistance, adhesion, and adhesion retention.

In addition, the intrinsic viscosity IV of the polyester resin constituting the P1 layer of the present invention is preferably 0.65 dl / g or more and 0.80 dl / g or less, and the polyester resin preferably contains polyethylene terephthalate (PET) as a main constituent. The main component here means that it is contained in excess of 50% by mass with respect to the polyester resin.

When the resin constituting the P1 layer contains PET as a main component, the intrinsic viscosity IV of the PET is preferably 0.65 dl / g or more, more preferably 0.69 dl / g or more, and the intrinsic viscosity IV is 0.00. When it is less than 65 dl / g, the heat and humidity resistance of the laminate may be deteriorated. Moreover, when intrinsic viscosity IV exceeds 0.80 dl / g, when the P1 layer is manufactured, the extrudability of the resin may be poor and sheet molding may be difficult. Therefore, when the resin constituting the P1 layer contains PET as the main constituent component, a laminate having both excellent moldability and wet heat resistance can be obtained by satisfying the above-described range of the intrinsic viscosity IV.

In the laminate of the present invention, the number average molecular weight Mn of the polyester resin constituting the P1 layer is preferably 8000 to 40000, more preferably 9000 to 30000, and still more preferably 10,000 to 20000. Here, the number average molecular weight Mn of the polyester resin constituting the P1 layer means that the P1 layer is separated from the laminate of the present invention, dissolved in hexafluoroisopronol (HEIP), and gel permeation chromatography (GPC method). This is a value obtained by using polyethylene terephthalate and dimethyl terephthalate having a known molecular weight as standard samples from the values measured by and detected with a differential refractometer.

When the number average molecular weight Mn of the polyester resin constituting the P1 layer is less than 8000, durability such as heat and moisture resistance and heat resistance may be lowered. On the other hand, when the number average molecular weight Mn exceeds 40000, even if the polymerization is difficult or the polymerization can be performed, it is difficult to extrude the resin with an extruder and the molding process may be difficult.

In the laminate of the present invention, the polyester resin constituting the P1 layer preferably contains at least one metal element selected from Mn, Ca, and Mg as a metal element. In particular, it is preferable to contain Mn element, and it is more preferable that Mn element and Na element are contained, and it is more preferable that Mn element is contained in the range of 50 to 200 ppm and Na element is contained in the range of 10 to 80 ppm. . When the P1 layer of the laminate of the present invention contains Mn element and Na element in the above ranges, hydrolysis of the polyester resin constituting the P1 layer is suppressed, and the moisture resistance and adhesion retention of the laminate are further improved. Can be increased.

In the laminate of the present invention, the P1 layer is preferably uniaxially or biaxially oriented. When the P1 layer is uniaxially or biaxially oriented, the durability of the sheet, such as moisture and heat resistance, can be improved by orientation crystallization.

For the purpose of imparting properties such as ultraviolet resistance, light reflectivity, light hiding property, designability, and visibility to the P1 layer of the present invention, a method of incorporating particles having respective functions is also preferably used. For example, in order to improve both ultraviolet resistance and light reflectivity, it is preferable to contain titanium oxide particles in the range of 1% by mass to 30% by mass with respect to the resin constituting the P1 layer. This makes it possible to take advantage of the ultraviolet absorption ability and light reflectivity of the titanium oxide particles to reduce the coloration due to light deterioration over a long period of time and the effect of increasing the power generation efficiency of the solar cell equipped with the laminate of the present invention. You can expect.

When titanium oxide particles are contained in the P1 layer of the present invention, if less than 1% by mass, UV resistance and light reflectivity may be insufficient, and if more than 30% by mass, adhesion to the P2 layer may deteriorate. is there. A more preferable range is 1% by mass or more and 25% by mass or less, further preferably 2% by mass or more and 25% by mass or less, and particularly preferably 3% by mass or more and 20% by mass or less. From the viewpoint of achieving both excellent ultraviolet resistance and light reflectivity, it is more preferable to use rutile titanium oxide as the titanium oxide particles.

Furthermore, in order to improve UV resistance, light hiding properties, and design, particles made of carbon-based materials such as fullerene, carbon black, carbon fiber, and carbon nanotube (hereinafter referred to as carbon particles) with respect to the resin constituting the P1 layer. ) Is preferably contained in the range of 0.1% by mass to 5% by mass. This makes it possible to exhibit the effect of reducing coloration due to light degradation of the laminate over a long period of time by utilizing the ultraviolet absorbing ability and light hiding property of the carbon particles. When the content is less than 0.1% by mass, the UV resistance may be insufficient. When the content is more than 5% by mass, the adhesion with the P2 layer may be deteriorated. A more preferable range is 0.2% by mass or more and 4% by mass or less, and further preferably 0.5% by mass or more and 3% by mass or less.

As a method of incorporating the particles into the polyester resin constituting the P1 layer of the present invention, a method of melt-kneading the polyester resin and particles using a vent type twin-screw kneading extruder or a tandem type extruder is preferably used. . Here, when the polyester resin is subjected to a heat load when the polyester resin contains particles, the polyester resin deteriorates not a little, and the amount of terminal carboxyl groups may increase, and the intrinsic viscosity IV and number average molecular weight may decrease. Therefore, a high-concentration master pellet having a content higher than that of the polyester resin finally constituting the P1 layer is prepared in advance, and mixed with the polyester resin to dilute the desired particles. By preparing the P1 layer adjusted to have a content, it is possible to enhance moisture heat resistance and adhesion retention with an easy adhesion layer.

In addition to the titanium oxide particles and carbon particles, the P1 layer in the laminate of the present invention may include a heat-resistant stabilizer, an oxidation-resistant stabilizer, and an ultraviolet absorber as long as the effects of the present invention are not impaired. , UV stabilizers, organic / inorganic lubricants, organic / inorganic fine particles, fillers, nucleating agents, dyes, dispersants, coupling agents, etc., and bubbles may be blended. . For example, when an ultraviolet absorber is selected as an additive, the ultraviolet resistance of the laminate of the present invention can be further improved. Add antistatic agents to improve electrical insulation, or to develop light reflectivity by containing organic / inorganic fine particles and bubbles, or add color material you want to color to improve design. It can also be granted.

The P1 layer of the present invention may have a laminated structure. For example, a laminated structure of a P11 layer excellent in heat and moisture resistance and a layer P12 layer containing a high concentration of an ultraviolet absorber or titanium oxide particles having an ultraviolet absorbing ability is preferably used. When the laminated body of the present invention is used as a solar cell back surface protection sheet or when a solar cell is mounted, such a P1 layer configuration is P12 layer / P11 layer // P2 layer. Is preferable from the viewpoint of achieving both UV resistance and UV resistance. In this case, as the resin and particles used for the P11 layer and the P12 layer, those exemplified for the P1 layer can be preferably used.

In the laminate of the present invention, the thickness of the P1 layer is preferably 30 μm or more and less than 500 μm. When the laminate of the present invention is used as a solar cell back surface protection sheet when the thickness of the P1 layer is less than 30 μm, for example, when the laminate of the present invention is mounted on a solar cell, the When used under voltage, dielectric breakdown may occur, which may be undesirable. On the other hand, if the thickness is greater than 500 μm, the processability of the laminate may deteriorate, and the overall thickness of the mounted solar battery cell may become too thick, which may be undesirable. Therefore, the preferable range of the thickness of the P1 layer is 38 μm or more and 400 μm or less, and more preferably 50 μm or more and 300 μm or less.

(P2 layer (hereinafter sometimes referred to as easy-adhesion layer))
The laminate of the present invention has a P2 layer as an easy-adhesion layer, and the surface energy of the P2 layer needs to satisfy the following ranges (1) and (2). The surface energy here is a value obtained by measurement by a method according to JIS K 6768 (1999), and will be described in detail later.
(1) Polar force γp is 4.8 mN / m or more and 21.0 mN / m or less (2) Difference γp−γh between polar force γp and hydrogen bonding force γh is 1.0 mN / m or more and 20.0 mN / m or less According to the conventional knowledge, when the P2 layer is to be improved in adhesion with a target adherend having a constant surface energy (for example, EVA), the surface energy of the P2 layer is determined as the surface energy of the adherend. It is considered effective to be close. In this method, since the affinity between the P2 layer and the adherend is increased by bringing the surface energy of the P2 layer close to the surface energy of the adherend, the initial adhesion can be improved.
However, the polyester resin and other components constituting the P1 layer and P2 layer of the laminate of the present invention are characterized in that the surface energy changes depending on the properties and the deterioration state of the polymer. Similarly, EVA, which is generally used as an adherend, for example, as a sealing material for solar cells, has a feature that the surface energy changes depending on the crosslinking state (crosslinking degree).
That is, in the present invention, when the P2 layer and the adherend are left outdoors for a long time, the surface energy changes with time. Therefore, even if the surface energy of the P2 layer is brought close to the surface energy of the adherend as described above, the adhesion is deteriorated after being left for a long period of time under wet heat conditions.
In view of the above phenomenon, the laminate of the present invention achieves both initial adhesion and long-term adhesion retention by setting the surface energy of the P2 layer to a range that satisfies the ranges of (1) and (2). It has such an effect. Hereinafter, (1) and (2) will be described in detail.

The polar force γp of the P2 layer in the present invention is one of the forces constituting the surface energy of the easy adhesion layer (P2 layer) and is an index representing the degree of intermolecular attractive force generated by the polarity in the molecule. . Since the difference in surface energy from the adherend or the P1 layer increases when the polar force γp of the easy-adhesion layer is less than 4.8 mN / m or more than 21.0 mN / m, initial adhesion and adhesion retention Sex is reduced.
Specifically, when the polar force γp of the P2 layer is less than 4.8 mN / m, when the amount of terminal carboxyl groups of the polyester resin constituting the P1 layer is small, or when the deterioration of the polyester resin proceeds, the easy adhesion layer And the difference in surface energy increases, and peeling at the interface of the base film (P1 layer) / easy-adhesive layer (P2 layer) is likely to occur, and the adhesion and adhesion retention deteriorate. In addition, since the difference in surface energy from the initial adherend increases with time, peeling at the interface between the easy-adhesion layer (P2 layer) and the adherend tends to occur, resulting in poor adhesion.
On the other hand, if the polar force γp of the P2 layer exceeds 21.0 mN / m, the difference in surface energy from the polyester resin constituting the P1 layer becomes large, so that the base film (P1 layer) / easily adhesive layer (P2 layer) ) Occurs at the interface, and adhesion and adhesion retention deteriorate. In addition, when EVA, which is a sealing material for solar cells, is used as an adherend, the difference in surface energy from the adherend increases with time when placed outdoors for a long period of time, and an easy adhesion layer (P2 layer). / Peeling at the interface of the adherend tends to occur, and the adhesiveness retention deteriorates.
In addition, the range of the polar force γp of the P2 layer described in (1) is preferably 5.4 mN / m or more and 12.0 mN / m or less, more preferably 6.0 mN / m or more and 8.4 mN / m or less.

Next, the hydrogen bonding force γh of the P2 layer in the present invention is an index representing the degree of interaction force between molecules due to the electronegativity of the easy-adhesion layer (P2 layer). Furthermore, in the present invention, it represents the degree of the component that affects the hydrolysis resistance of the easily adhesive layer (P2 layer). That is, in the present invention, the difference between the polar force γp and the hydrogen bonding force γh of the P2 layer represents a balance between the affinity of the adherend and the easy adhesion layer (P2 layer) with the P1 layer and the hydrolysis resistance. Is.
Here, the difference γp−γh between the polar force γp and the hydrogen bond force γh described in (2) is preferably 2.5 mN / m or more and 9.0 mN / m or less, preferably 3.7 mN / m or more and 4.9 mN / m. m or less is more preferable. When the difference γp-γh between the polar force γp and the hydrogen bonding force γh of the P2 layer is less than 1.0 mN / m, hydrolysis of the easy-adhesion layer can be suppressed, but at the same time, the component contributing to adhesion is insufficient. The adhesion strength itself decreases. On the other hand, if it exceeds 20.0 mN / m, the cohesive force decreases due to hydrolysis of the easy-adhesion layer.
That is, in the present invention, by setting the difference γp−γh between the polar force γp and the hydrogen bonding force γh of the P2 layer in the above range, for example, when EVA which is a sealing material for solar cells is used as an adherend Even when placed outdoors for a long period of time, the difference in surface energy between the P2 layer and EVA can be reduced, and the adhesion retention can be improved.
Furthermore, the hydrogen bonding force γh of the P2 layer is preferably 1.0 mN / m or more and 4.5 mN / m or less, and the hydrogen bonding force γh of the P2 layer is within the above preferable range, The effect which suppresses the improvement of the adhesiveness of P2 layer and the hydrolysis of P2 layer can be expected more.

The surface energy mentioned above can be appropriately adjusted depending on the resin component and content contained in the P2 layer. Specifically, for example, in order to increase the polar force γp of the P2 layer, it is effective to use a urethane resin component, a melamine resin component, and a polyester resin component together as the resin component contained in the P2 layer. On the other hand, in order to reduce the polar force γp, it is effective to use a urethane resin component and an oxazoline resin component in combination as the resin component contained in the P2 layer.
In particular, when the P2 layer contains only the urethane resin component, the polar force γp may be significantly increased. In addition, when the polyester resin component used in combination is an acrylic-modified polyester resin component, the polar force γp is increased. However, when the structure of the acrylic modified portion is an acrylic polymer obtained by polymerizing a hydrophilic radical polymerizable vinyl monomer, the polar force is increased. The increase width of γp can be reduced.

Similarly, in order to increase the hydrogen bond strength γh, it is effective to increase the amount of the oxazoline resin component contained in the P2 layer. Conversely, when it is desired to reduce the hydrogen bond strength γh, the amount of the oxazoline resin component is suppressed. Just do it. Further, the amount of the melamine resin component and the urethane resin component is somewhat affected, and in order to increase the hydrogen bond strength γh, the amount of the melamine resin component is increased and the amount of the urethane resin component is decreased. Conversely, in order to reduce the hydrogen bonding force γh, the amount of the melamine resin component should be small and the amount of the urethane resin component should be large. In the case where the urethane resin component contained in the P2 layer is a urethane resin made of a polycarbonate polyol compound, the hydrogen bonding force γh may be significantly increased.
Here, the quantity of each resin component contained in P2 layer can be adjusted with the addition amount of each resin component contained in the coating composition which comprises P2 layer.

Although details are not well understood at present, the polar force γp and the hydrogen bonding force γh may vary depending on the thickness of the P2 layer even when the P2 layer is the same component. For example, it is assumed that when the thickness of the P2 layer is increased, the temperature history experienced by the P2 layer is changed at the stage of forming the P2 layer, and the cross-linked structure is changed. On the other hand, when the thickness is reduced, it is presumed that the surface condition has changed due to being easily affected by thickness unevenness. Therefore, in the present invention, the thickness of the P2 layer is preferably 0.1 μm or more and 3.0 μm or less. By setting the thickness of the P2 layer within the above range, it is possible to reduce the change in the surface energy value due to the uneven thickness of the P2 layer and the influence of the resin component constituting the P2 layer, and to improve the adhesion.

The resin component contained in the P2 layer referred to here is an X-ray photoelectron spectrometer (ESCA), Fourier infrared spectrophotometer (FT-IR) ATR method, time-of-flight secondary ion mass spectrometer on the surface of the P2 layer. (TOF-SIMS) or P2 layer is dissolved and extracted with a solvent, and proton nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy ( ¹³ C-NMR), Fourier infrared spectrophotometer (FT -IR), or by separating the P2 layer and performing a qualitative analysis of the P2 layer, such as by chromatography mass spectrometry (GC-MS).

Hereinafter, the components that are preferable to be contained in the P2 layer of the laminate of the present invention will be described in detail, but are not particularly limited as long as the effects of the present invention are not impaired.

The P2 layer of the present invention preferably contains three components, a urethane resin component, a melamine resin component, and an oxazoline resin component. The urethane resin component here means a component comprising a resin having a urethane bond obtained by reaction of a polyol compound and a polyisocyanate compound in the main chain, and a resin obtained by reacting the resin with other components. Show.

Specifically, from the viewpoint of affinity with the adherend, it is preferable to polymerize an aliphatic polyisocyanate compound and a polyol compound, and the aliphatic polyisocyanate compound has a plurality of isocyanate groups in the molecule. For example, 1,6-hexane diisocyanate, isophorone diisocyanate, toluene diisocyanate, methylene bis (4-cyclohexyl isocyanate), 2,2,4-trimethylhexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, bis (2-isocyanate) Ethyl) fumarate, bis (4-isocyanatocyclohexyl) methane, dicyclohexylmethane 4,4-diisocyanatotrizine diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated phenylmethanedi Such as isocyanate and the like, aliphatic polyisocyanate compounds having an alicyclic structure from the viewpoint of enhancing the durability of inter alia P2 layer is more preferred.

Examples of the polyol compound include aromatic polyether polyol, aliphatic polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

Specific examples of the aromatic polyether polyol include bisphenol A ethylene oxide addition diol, bisphenol A propylene oxide addition diol, bisphenol A butylene oxide addition diol, bisphenol F ethylene oxide addition diol, and bisphenol F propylene oxide. An addition diol, a propylene oxide addition diol of bisphenol F, an alkylene oxide addition diol of hydroquinone, an alkylene oxide addition diol of naphthoquinone, and the like.

Examples of the aliphatic polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, polyisobutylene glycol, a copolymer polyol of propylene oxide and tetrahydrofuran, and a copolymer of ethylene oxide and tetrahydrofuran. Copolymer polyol, copolymer polyol of ethylene oxide and propylene oxide, copolymer polyol of tetrahydrofuran and 3-methyltetrahydrofuran, copolymer polyol of ethylene oxide and 1,2-butylene oxide, and aliphatic polyether polyol Examples of the cyclic polyether polyol include hydrogenated bisphenol A ethylene oxide addition diol and hydrogenated bisphenol A Rene oxide addition diol, hydrogenated bisphenol A butylene oxide addition diol, hydrogenated bisphenol F ethylene oxide addition diol, hydrogenated bisphenol F propylene oxide addition diol, hydrogenated bisphenol F butylene oxide addition diol, dicyclopentadiene dimethylol Examples thereof include compounds and tricyclodecane dimethanol.

Examples of the polyester polyol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, and 3-methyl. Polyhydric alcohols such as 1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, Mention may be made of polyester polyols obtained by reacting with polybasic acids such as sebacic acid.

Examples of the polycarbonate polyol include 1,6-hexane polycarbonate.

Examples of the polycaprolactone polyol include ε-caprolactone and ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neo Examples thereof include polycaprolactone diols obtained by reacting divalent diols such as pentyl glycol, 1,4-cyclohexanedimethanol and 1,4-butanediol.

Other polyol compounds that can be used in the present invention include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4 -Cyclohexanedimethanol, poly β-methyl-δ-valerolactone, hydroxy-terminated polybutadiene, hydroxy-terminated hydrogenated polybutadiene, castor oil-modified polyol, polydimethylsiloxane-terminated diol compound, polydimethylsiloxane carbitol-modified polyol, etc. .

Among them, polyether polyol is preferable from the viewpoint of improving the adhesiveness with the adherend by softening the P2 layer, and aromatic polyols and the like from the viewpoint of improving the adhesiveness with the P1 layer. Polyester polyol is preferred. Moreover, you may use combining these.

The urethane resin component contained in the P2 layer is an isocyanate compound that can increase the affinity and durability with the adherend, a polyol compound that can soften P2, and a urethane resin obtained by polymerizing a polyol compound that is excellent in adhesion to the P1 layer. By doing so, it is possible to improve the adhesion retention after the acceleration test.

These urethane resins are obtained by using commercially available resins such as DIC's Hydran series, Bondic series, Daiichi Kogyo Seiyaku Co., Ltd. Superflex series, Toa Gosei Co., Ltd. Aron Neotan series, etc. You can also.

Next, a preferable melamine resin component contained in the P2 layer is a component comprising a resin having a triazine ring in the molecule and three amino groups in the periphery thereof, and a resin obtained by reacting the resin with other components. Indicates. Specifically, hexamethylol melamine, hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexakis- (hexatype (the number of functional groups bonded to three amino groups directly bonded to the triazine ring is 6)) Methoxymethyl) melamine, tri-type (three functional groups bonded to three amino groups directly bonded to the triazine ring) N, N ′, N ″ -trimethyl-N, N ′, N ″ -trimethylol melamine, N, N ′, N ″ -trimethylol melamine, N-methylol melamine, N, N ′-(methoxymethyl) melamine, N, N ′, N ″ -tributyl-N, N ′, N ″ -trimethylolmelamine and the like can be mentioned.

By including the melamine resin component in the P2 layer, it is possible to increase the cohesive force of the P2 layer by a self-condensation reaction, and as a result, it is possible to increase adhesion by suppressing cohesive failure.

In addition, these melamine resins can also be obtained by using commercially available resins such as, for example, Becamine series manufactured by DIC Corporation, and Nicarak series manufactured by Sanwa Chemical Co., Ltd.

Next, a preferable oxazoline resin component contained in the P2 layer indicates a component comprising a resin having an oxazoline group structure in the molecule and a resin obtained by reacting the resin with other components. Specifically, 1,4-bis (4,5-dihydro-2-oxazolyl) benzene, bisoxazolines (low molecular oxazoline group-containing compounds) such as 2,2′-bis (2-oxazoline), polyolefins And oxazoline group-modified compounds in which oxazoline groups are introduced with polystyrene as a skeleton structure.

By including the oxazoline resin component in the P2 layer, the terminal group present in the P2 layer or the terminal carboxyl group derived from the polyester resin of the P1 layer reacts with the oxazoline group, and the hydrolysis of the P2 layer is suppressed. It is possible to improve the adhesion.

In addition, these oxazoline resins can also be obtained and used, for example, commercially available resins such as Nippon Shokubai Epocross series.

The P2 layer of the present invention preferably contains a polyester resin component. Here, the polyester resin component preferably contained in the P2 layer is to introduce a hydrophilic group such as a sulfonate group or a carboxylate group in order to make the polyester resin exemplified in the P1 layer water-soluble or facilitate water dispersion. Or a resin comprising a copolymer obtained by copolymerizing a compound containing these hydrophilic groups and a resin obtained by reacting the resin with other components.
Specifically, for example, the compound containing a sulfonate group includes sulfoterephthalic acid, 5-sulfoisophthalic acid, 5-sodium sulfoisophthalic acid, 4-sulfoisophthalic acid, and the like. , Trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3 , 4-pentanetetracarboxylic acid, alkali metal salts, alkaline earth metal salts, ammonium salts, and the like.

When the polyester resin component is contained in the P2 layer, it is possible to increase the affinity with the P1 layer, and as a result, it is possible to increase the adhesion.

Further, the polyester resin component contained in the P2 layer is preferably an acrylic-modified polyester resin component. By making the polyester resin component contained in the P2 layer an acrylic-modified polyester resin component, it becomes possible to increase the affinity with other components such as the urethane resin component contained in the P2 layer, and by separating the resin component Cohesive failure can be suppressed.

The acrylic-modified polyester resin component here is a component composed of a resin in which an acrylic resin and a polyester resin are mixed and / or bonded to each other, and includes, for example, a graft type and a block copolymer type. Further, either the mixing ratio or copolymerization ratio of the acrylic resin and the polyester resin may be high, and it is preferable to appropriately adjust depending on the relationship with other resin components.
Specifically, the acrylic resin preferably has a radical polymerizable vinyl monomer polymerized on the main chain of the acrylic resin composed of alkyl methacrylate and / or alkyl acrylate, and the difference in energy from the adherend. It is more preferable that a hydrophilic radically polymerizable vinyl monomer is polymerized from the viewpoint of reducing the size.

Specific examples of the alkyl methacrylate and / or alkyl acrylate include methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, methacrylic acid. 2-hydroxyethyl acid, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-acrylic acid 2- Examples thereof include ethylhexyl, and these may be used alone or in combination of two or more.

Specific examples of hydrophilic radically polymerizable vinyl monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and other hydroxyacrylic esters, ethylene glycol acrylate, and ethylene. Glycol esters such as glycol methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, acrylamide compounds such as acrylamide, methacrylamide, N-methylol acrylamide, methoxymethylol acrylamide, aminoalkyl acrylate, aminoalkyl methacrylate, and quaternary ammonium thereof Cationic monomers such as salts, glycidyl acrylate, glycidyl methacrylate, etc. Examples include diacrylate compounds, unsaturated acids such as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and crotonic acid, and salts thereof. These may be used alone or in combination. May be. Furthermore, these hydrophilic monomers can be used in combination with other copolymerizable vinyl monomers.

Specific examples of other copolymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate, vinyl halides such as vinyl chloride and vinyl bromide, methyl acrylate, ethyl acrylate, and butyl acrylate. , Unsaturated carboxylic esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, vinyl silanes such as dimethylvinylmethoxysilane and γ-methacryloxypropyltrimethoxysilane, olefins and diolefins such as ethylene, propylene, styrene and butadiene Compound etc. are mentioned.

When the polyester resin component is contained in the P2 layer of the laminate of the present invention, P2 is obtained by making the acrylic resin an acrylic resin in which a hydrophilic radically polymerizable vinyl monomer is polymerized with an acrylic-modified polyester resin. It can be set as the laminated body which made compatible adhesiveness, after suppressing the separation in a layer.

Note that these acrylic-modified polyester resins can be obtained by using commercially available resins such as the Pes Resin series manufactured by Takamatsu Yushi Co., Ltd.

The P2 layer of the laminate of the present invention is a layer formed from a coating composition containing the above resin component. Here, when the urethane resin component is contained in the P2 layer, the content in the P2 layer or the solid content in the coating composition forming the P2 layer is preferably 40% by mass or less, preferably 10% by mass or more. 30 mass% or less is more preferable.

Further, when the melamine resin component is contained in the P2 layer, the content in the P2 layer is preferably contained in the range of 1% by mass to 20% by mass, and more preferably 7% by mass to 16% by mass. In order to obtain a P2 layer containing 1% by mass to 20% by mass of the melamine resin component in the P2 layer, the P2 layer is formed from a coating composition containing the melamine resin component by 1% by mass to 20% by mass in terms of solid content. It is preferable to make it. More preferably, it is 7 mass% or more and 16 mass% or less.

When the oxazoline resin component is contained in the P2 layer, the content in the P2 layer is preferably contained in the range of 1% by mass to 20% by mass, and more preferably in the range of 10% by mass to 18% by mass. In order to obtain a P2 layer containing 1% by mass to 25% by mass of the oxazoline resin component in the P2 layer, the P2 layer is formed from a coating composition containing 1% by mass to 25% by mass of the oxazoline resin component in terms of solid weight. It is preferable to make it. More preferably, it is 10 mass% or more and 18 mass% or less.

Further, when the polyester resin component or the acrylic resin-modified polyester resin component is contained in the P2 layer, the content in the P2 layer is preferably 30% by mass or more and 75% by mass or less, and preferably 40% by mass or more and 50% by mass. The following is more preferable. In order to obtain a P2 layer containing 30% by mass or more and 75% by mass or less of an acrylic-modified polyester resin component in the P2 layer, a coating containing 30% by mass or more and 75% by mass or less of an acrylic-modified polyester resin component by solid content weight. The P2 layer is preferably formed from the agent composition. More preferably, it is 40 mass% or more and 50 mass% or less.

When the P2 layer of the laminate of the present invention contains the urethane resin component, melamine resin component, oxazoline resin component, polyester resin component or acrylic-modified polyester resin component, the content in the P2 layer, or the P2 layer is When the solid content weight in the coating composition to be formed is smaller than the above preferred range, the effect expected of each resin component may be insufficient. On the other hand, when larger than a preferable range, there exists a possibility of inhibiting the effect of another component.

Further, the thickness of the P2 layer in the laminate of the present invention is preferably 0.1 μm or more and 3.0 μm or less, more preferably 0.2 μm or more and 2.0 μm or less, and further preferably 0.4 μm or more and 1.0 μm or less. is there. When the thickness of the P2 layer in the laminate of the present invention is less than 0.1 μm, the thickness unevenness of the P2 layer becomes large, and the surface energy value may change due to the influence, or the function of the P2 layer may be insufficient. . On the other hand, when the thickness of the P2 layer is thicker than 3.0 μm, the winding property and the coating property may be deteriorated due to insufficient drying.

That is, by making the resin components contained in the P2 layer of the laminate of the present invention, their content, and the thickness of the P2 layer into a preferable range, the surface energy in the laminate of the present invention is the above (1) and ( A P2 layer satisfying the range of 2) can be obtained. Thereby, excellent adhesion to an adherend such as EVA which is a sealing material for solar cells, and a polyester having a terminal carboxyl group amount of 25 equivalents / ton or less as in the P1 layer in the laminate of the present invention. Even if it is a base material, it is possible to achieve both good adhesion and maintain the adhesion even when placed outdoors for a long time (excellent adhesion retention). It can be set as a suitable laminated body.

In addition, the P2 layer of the laminate of the present invention has a known heat stabilizer, lubricant, antistatic agent, anti-blocking agent, dye, pigment, photosensitizer, and surface activity, as long as the effects of the present invention are not impaired. Various additives such as an agent and an ultraviolet absorber can be added.

For example, when the laminate of the present invention is mounted on a solar cell as a solar cell back surface protection sheet by adding an ultraviolet absorber to the P2 layer, the laminate and the sealing material are adhered to each other by ultraviolet rays from the power generation cell side. It can suppress that property falls. In this case, as the ultraviolet absorber, inorganic particles such as titanium oxide and zinc oxide, those containing an ultraviolet absorber, and a resin component copolymerized with a molecular skeleton having ultraviolet absorbing ability are preferably used and preferably contained. The amount of the solid content in the coating composition forming the P2 layer is 1% by weight to 50% by weight, more preferably 5% by weight to 40% by weight, and still more preferably 10% by weight to 30% by weight. It is.

Further, the P2 layer of the laminate of the present invention may have a laminate structure for the purpose of further improving the adhesion with the adherend. For example, an anchor coat layer (referred to as P21 layer) having excellent adhesion with the P1 layer is provided in advance on one surface of the P1 layer, and a layer (referred to as P22 layer) that is further excellent in easy adhesion on the P21 layer. The providing method is also preferably used. In that case, the structure of the sheet is laminated in the order of P1 layer // P21 layer / P22 layer, and the thickness of the P2 layer is represented by P21 layer + P22 layer.
At this time, the P21 layer has good adhesiveness with the resin constituting the P1 layer and the P22 layer, and the P22 layer has excellent adhesiveness with the resin constituting the P21 layer and the adherend. When it is mounted on a solar battery as a battery back surface protection sheet, it is not particularly limited as long as it is compatible with the sealing material at the temperature at the time of thermocompression laminating at the time of solar battery cell creation. Moreover, what was illustrated by said P2 layer can be suitably used suitably for resin used for P21 layer and P22 layer.

Furthermore, blocking at the time of winding can be prevented by adding silica particles as an anti-blocking agent to the P2 layer. Further, by adding a surfactant to the P2 layer, it is possible to increase the affinity of the coating liquid for the P1 layer and suppress coating unevenness.

(Laminate manufacturing method)
Next, an example is given and demonstrated about the manufacturing method of the laminated body of this invention. This is an example, and the present invention should not be construed as being limited to the product obtained by such an example.

First, the polyester resin used as a raw material for the P1 layer of the present invention can be obtained by subjecting a dicarboxylic acid or its ester derivative and a diol to a transesterification reaction or an esterification reaction by a known method. Examples of conventionally known reaction catalysts include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and phosphorus compounds. Preferably, an alkali metal compound, a manganese compound, an antimony compound, a germanium compound, or a titanium compound is preferably added as a polymerization catalyst at any stage before the normal production method is completed, and the viewpoint of improving the heat and moisture resistance of the laminate It is more preferable to add a sodium compound or a manganese compound. As such a method, for example, when a manganese compound is taken as an example, it is preferable to add the manganese compound powder as it is.

The amount of terminal carboxyl groups of the polyester resin is the temperature at the time of polymerization, or after polymerization of the polyester resin, at a temperature of 190 ° C. to less than the melting point of the polyester resin, and heated under reduced pressure or an inert gas such as nitrogen gas. The so-called solid-state polymerization time can be controlled. Specifically, the amount of terminal carboxyl groups increases as the polymerization temperature increases, and the amount of terminal carboxyl groups decreases as the time of solid phase polymerization increases.

Next, when the P1 layer has a single film structure, the P1 layer manufacturing method is a method in which the P1 layer raw material is heated and melted in an extruder and extruded from a die onto a cooled cast drum (a melt casting method). ) Can be used. As another method, the raw material for the P1 layer is dissolved in a solvent, and the solution is extruded from a die onto a support such as a cast drum or an endless belt to form a film, and then the solvent is dried and removed from the film layer. A method of processing into a shape (solution casting method) or the like can also be used. In addition, when the P1 layer has a laminated structure, when the material of each layer to be laminated is mainly composed of a thermoplastic resin, two different thermoplastic resins are put into two extruders and melted to join. Thus, a method of coextrusion onto a cast drum cooled from the die and processing it into a sheet (coextrusion method) can be preferably used.

When a uniaxial or biaxially stretched sheet base material is selected as a laminate including the P1 layer and / or the P1 layer, as a manufacturing method thereof, first, an extruder (a plurality of extruders in the case of a laminated structure) is used. The raw materials are charged, melted and extruded from the die (in the case of a laminated structure, co-extruded), and cooled and solidified by static electricity on a cooled drum cooled to a surface temperature of 10 to 60 ° C. to produce an unstretched sheet .

Next, the unstretched sheet is led to a group of rolls heated to a temperature of 70 to 140 ° C., stretched 3 to 4 times in the longitudinal direction (longitudinal direction, that is, the traveling direction of the sheet), and the temperature is 20 to 50 ° C. Cool with rolls. Subsequently, the both ends of the sheet are guided to a tenter while being gripped by clips, and are stretched 3 to 4 times in a direction (width direction) perpendicular to the longitudinal direction in an atmosphere heated to a temperature of 80 to 150 ° C.

The stretching ratio is 3 to 5 times in each of the longitudinal direction and the width direction, but the area ratio (longitudinal stretching ratio × lateral stretching ratio) is preferably 9 to 15 times. When the area magnification is less than 9 times, the durability of the resulting biaxially stretched sheet is insufficient, and conversely when the area magnification exceeds 15 times, there is a tendency that tearing tends to occur during stretching. As the biaxial stretching method, in addition to the sequential biaxial stretching method in which the stretching in the longitudinal direction and the width direction is separated as described above, simultaneous biaxial stretching in which stretching in the longitudinal direction and the width direction is simultaneously performed. Either method can be used.

As a method for preparing a coating composition for forming a P2 layer in the laminate of the present invention, as a dispersion solvent for resin components, for example, toluene, xylene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone , Tetrahydrofuran, dimethylformamide, dimethylacetamide, methanol, ethanol, water and the like, and any of emulsion type and dissolution type may be used.
Further, in recent years, importance has been given to environmental protection, resource saving, exhaust problems of organic solvents at the time of production, etc., and a dissolved type or an emulsion type mainly composed of water is the preferred form. The method for emulsifying the resin component contained in the P2 layer in water for preparing the coating composition is not particularly limited, and is widely known to those skilled in the art as a solid / liquid stirring device or an emulsifier. It can be produced by a device.

Also, after preparing the coating composition for forming the P2 layer, the environment for storage is preferably stored in a room temperature environment of 5 ° C. or more and 35 ° C. or less. The storage period from adjustment to application is preferably within one week. When the storage environment of the coating composition does not satisfy the above conditions, the stability of the dispersed resin component is impaired, and a P2 layer having desired characteristics may not be obtained.

Next, the method for forming the P2 layer on the P1 layer is not particularly limited, but it is preferable to use a coating technique. A known method can be applied as a coating technique. Specifically, a roll coating method, a dip coating method, a bar coating method, a die coating method, a gravure roll coating method, or a combination of these methods can be used. Among them, the bar coating method is preferable from the viewpoint of a wide selection range of the coating agent, while the die coating method and the gravure roll coating method can be preferably selected from the viewpoint of thick film coating property when it is desired to increase the thickness of the P2 layer.

Furthermore, it is more preferable to form the P2 layer by in-line coating provided in the manufacturing process of the P1 layer from the viewpoint of process simplification. Specifically, in the case of the sequential biaxial stretching method, after forming an unstretched sheet or a uniaxially stretched sheet, in the case of the simultaneous biaxial stretching method, after forming the unstretched sheet, the above coating step After applying the coating composition for forming the P2 layer, the P1 layer is heat-set simultaneously with the drying step of the coating composition. At this time, the drying temperature of the coating composition is preferably 150 ° C. or higher and 250 ° C. or lower, more preferably 170 ° C. or higher and 230 ° C. or lower, and still more preferably, from the viewpoint of the compatibility between the thermal dimensional stability and the wet heat resistance of the base layer P1. Is 180 ° C. or higher and 220 ° C. or lower.

Further, if necessary, from the viewpoint of improving the wettability of the coating composition to the P1 layer and improving the interlayer adhesion after the formation of the P2 layer, a corona treatment is performed on the surface of the base material layer P1 immediately before the coating step. Also good.

The laminate of the present invention can be manufactured by the above manufacturing method. The obtained laminate is excellent in adhesiveness with EVA which is a sealing material for solar cells, maintains adhesiveness even when placed outdoors for a long time (excellent retention property), and further has heat and moisture resistance. It also has the performance of being excellent.

(Solar cell backside protection sheet)
Next, an example in which the laminate of the present invention is applied as a solar cell back surface protection sheet will be described.
The solar cell back surface protective sheet of the present invention has other functions such as gas barrier property and ultraviolet resistance on one surface of the P1 layer of the laminate (however, the surface opposite to the surface in contact with the P2 layer). A layer can be provided. As a method of providing these layers, a method of separately preparing materials to be laminated with the P1 layer and thermocompression bonding with a heated group of rolls (thermal laminating method), a method of bonding together with an adhesive (adhesion method) ) In addition, a method of dissolving the material for forming the material to be laminated in a solvent and applying the solution onto the P1 layer prepared in advance (coating method), electromagnetic wave irradiation after applying a curable material onto the P1 layer A method of curing by heat treatment or the like, a method of depositing / sputtering a material to be laminated on the P1 layer, a method combining these, and the like can be used.

Moreover, it is preferable that the solar cell back surface protection sheet of this invention is excellent in heat-and-moisture resistance. Specifically, the elongation at break after applying the wet heat treatment to the solar cell back surface protective sheet of the present invention is preferably 10% or more, more preferably 20% or more, and further preferably 40% or more. The details of the method for measuring the elongation at break after the wet heat treatment here will be described later.
In the solar cell back surface protection sheet of the present invention, when the breaking elongation after applying wet heat treatment is less than 10%, when the solar cell equipped with the solar cell back surface protection sheet of the present invention is placed outdoors for a long time In addition, cracks and the like due to deterioration may occur and the appearance of the solar cell may deteriorate.
In order to improve the heat and moisture resistance in the solar cell back surface protection sheet of the present invention, polyethylene having an intrinsic viscosity IV of 0.65 dl / g or more and a terminal carboxyl group content of 25 equivalents / ton or less is used for the polyester resin constituting the P1 layer. A preferable method is to use terephthalate. By setting the intrinsic viscosity IV and the terminal carboxyl group amount of the polyester resin constituting the P1 layer within the above ranges, it is possible to improve the elongation at break after applying the wet heat treatment.

The solar cell back surface protective sheet of the present invention is preferably excellent in ultraviolet resistance. Specifically, it is preferable that the color tone change Δb when the ultraviolet ray treatment test is performed using the P1 layer of the solar cell back surface protective sheet of the present invention as an incident surface is less than 10, more preferably less than 3. Details of the method for measuring the color tone change Δb when the ultraviolet treatment test is performed will be described later.
In the solar cell back surface protection sheet of the present invention, when the color change Δb when the ultraviolet treatment test is performed with the P1 layer as the incident surface exceeds 10, the solar cell mounted with the solar cell back surface protection sheet of the present invention is long. When placed outdoors during the period, the appearance of the solar cell may deteriorate due to discoloration due to ultraviolet rays.
In the solar cell back surface protective sheet of the present invention, in order to make the range excellent in UV resistance, it is mentioned as a preferable method that titanium oxide particles are added in an amount of 3% by mass or more with respect to the P1 layer. It is possible to reduce the color tone change Δb depending on the amount added.

In the solar cell back surface protection sheet of the present invention, a solar cell back surface protection sheet excellent in moist heat resistance and ultraviolet resistance is used for a long time outdoors with the solar cell mounted with the solar cell back surface protection sheet of the present invention. Even if it is placed, it can be a solar cell having no appearance defect.

(Solar cell)
Next, an example in which the laminate of the present invention is mounted on a solar cell will be described.
The solar cell of the present invention is characterized in that the laminate of the present invention is mounted as a back surface protection sheet. The solar cell of the present invention can increase the durability as compared with a conventional solar cell by using the above laminate. An example of the configuration is shown in FIG. A power generating element connected with a lead wire for taking out electricity (not shown in FIG. 1) is sealed with a transparent sealing material 2 such as EVA resin, a transparent substrate 4 such as glass, and a solar cell back surface protection Although it is configured to be bonded as the sheet 1, it is not limited to this and can be used for any configuration. In addition, in FIG. 1, although the solar cell back surface protection sheet shows an example of a single body, the solar cell back surface protection sheet should be a composite sheet in which other films are laminated according to other required characteristics. Is also possible.

Here, in the solar cell of the present invention, the solar cell back surface protection sheet 1 plays a role of protecting the power generation cell installed on the back surface of the sealing material 2 sealing the power generation element. Here, the solar cell back surface protection sheet is preferably arranged so that the P2 layer is in contact with the sealing material 2. By adopting this configuration, the durability of the solar cell can be enhanced by protecting the power generation cell for a long period of time even when exposed to the outdoors, taking advantage of the excellent adhesion of the present invention.

The power generating element 3 converts light energy of sunlight into electric energy, and is based on crystalline silicon, polycrystalline silicon, microcrystalline silicon, amorphous silicon, copper indium selenide, compound semiconductor, dye enhancement Arbitrary elements such as a sensitive system can be used in series or in parallel according to the desired voltage or current depending on the purpose. Since the transparent substrate 4 having translucency is located on the outermost surface layer of the solar cell, a transparent material having high weather resistance, high contamination resistance, and high mechanical strength characteristics in addition to high transmittance is used. In the solar cell of the present invention, the transparent substrate 4 having translucency can be made of any material as long as the above characteristics are satisfied. Examples thereof include glass, ethylene tetrafluoride-ethylene copolymer (ETFE), polyfluoride. Vinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polytrifluoroethylene chloride resin (CTFE) ), Fluorinated resins such as polyvinylidene fluoride resin, olefinic resins, acrylic resins, and mixtures thereof. In the case of glass, it is more preferable to use a tempered glass. Moreover, when using the resin-made translucent base material, what extended | stretched the said resin uniaxially or biaxially from a viewpoint of mechanical strength is used preferably. Moreover, in order to give these substrates the adhesiveness with EVA resin etc. which are the sealing materials of an electric power generation element, it is also preferably performed to give the surface a corona treatment, a plasma treatment, an ozone treatment, and an easy adhesion treatment. .

The sealing material 2 for sealing the power generating element covers the surface of the power generating element with resin and fixes it, protects the power generating element from the external environment, and has a light-transmitting base material for the purpose of electrical insulation. In addition, a material having high transparency, high weather resistance, high adhesion, and high heat resistance is used to adhere to the backsheet and the power generation element. Examples thereof include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA) resin, ethylene-methacrylic acid copolymer (EMAA), Ionomer resins, polyvinyl butyral resins, and mixtures thereof are preferably used.

As described above, by incorporating the laminate of the present invention into a solar cell as a solar cell back surface protection sheet, it becomes possible to enhance the durability as compared with a conventional solar cell. The solar cell of the present invention can be suitably used for various applications without being limited to outdoor use and indoor use such as a solar power generation system and a power source for small electronic components.

[Measurement method and evaluation method of characteristics]
(1) Polymer characteristics (1-1) Amount of terminal carboxyl groups (in the table, described as COOH amount)
The terminal carboxyl group amount was measured by the following method according to the method of Malice. (Reference: M. J. Malice, F. Huizinga, Anal. Chim. Acta, 22 363 (1960))
2 g of a measurement sample (polyester resin (raw material) or separated P1 layer of the laminate) was dissolved in 50 mL of o-cresol / chloroform (weight ratio 7/3) at a temperature of 80 ° C., and 0.05 N KOH / The solution was titrated with a methanol solution, the terminal carboxyl group concentration was measured, and the value was represented by the value of equivalent / polyester 1t. In addition, the indicator at the time of titration used phenol red, and the place where it changed from yellowish green to light red was set as the end point of titration. If there is insoluble matter such as inorganic particles in the solution in which the measurement sample is dissolved, the solution is filtered to measure the weight of the insoluble matter, and the value obtained by subtracting the weight of the insoluble matter from the measurement sample weight The following correction was made.

(1-2) Intrinsic viscosity IV
In 100 ml of orthochlorophenol, a measurement sample (polyester resin (raw material) or a layer separated from the P1 layer alone) is dissolved (solution concentration C (measurement sample weight / solution volume) = 1.2 g / ml). The viscosity of the solution at 25 ° C. was measured using an Ostwald viscometer. Similarly, the viscosity of the solvent was measured. [Η] was calculated by the following formula (4) using the obtained solution viscosity and solvent viscosity, and the obtained value was defined as the intrinsic viscosity (IV).
ηsp / C = [η] + K [η] ² · C (4)
(Where ηsp = (solution viscosity / solvent viscosity) −1, K is the Huggins constant (assuming 0.343))
In addition, when there existed insoluble matters, such as inorganic particles, in the solution in which the measurement sample was dissolved, the measurement was performed using the following method.
(I) A measurement sample is dissolved in 100 mL of orthochlorophenol to prepare a solution having a solution concentration higher than 1.2 mg / mL. Here, let the weight of the measurement sample used for orthochlorophenol be a measurement sample weight.
(Ii) Next, the solution containing insoluble matter is filtered, and the weight of the insoluble matter is measured and the volume of the filtrate after filtration is measured.
(Iii) Orthochlorophenol was added to the filtrate after filtration, and (measured sample weight (g) −insoluble matter weight (g)) / (volume of filtrate after filtration (mL) + added orthochlorophenol) The volume (mL) is adjusted to 1.2 g / 100 mL.
(For example, when a concentrated solution having a measurement sample weight of 2.0 g / solution volume of 100 mL was prepared, the weight of insoluble matter when the solution was filtered was 0.2 g, and the filtrate volume after filtration was 99 mL Adjust to add 51 mL of orthochlorophenol ((2.0 g-0.2 g) / (99 mL + 51 mL) = 1.2 g / mL))
(Iv) Using the solution obtained in (iii), the viscosity at 25 ° C. is measured using an Ostwald viscometer, and using the obtained solution viscosity and solvent viscosity, η] is calculated, and the obtained value is defined as intrinsic viscosity (IV).

(1-3) Metal Element Content Regarding the P1 layer of the laminate, the Mg, Mn, and Sb metal element amounts are determined by the fluorescent X-ray analysis method (fluorescence X-ray analyzer manufactured by Rigaku Corporation (model number: 3270)). The Na metal element was quantified by atomic absorption spectrometry (manufactured by Tadate Corporation: polarization Zeeman atomic absorption photometer 180-80, frame: acetylene-air).

(2) Surface free energy The surface energy was measured by the following method according to the method of JIS K 6768 (1999). First, the laminate was allowed to stand for 48 hours in an atmosphere having a room temperature of 23 ° C. and a relative humidity of 65%. Thereafter, the contact angle of each of the four solutions of pure water, ethylene glycol, formamide, and diiodomethane was contact angle meter CA-D type (Kyowa Interface Science Co., Ltd.) under the same atmosphere. ) To measure 5 points each. The average value of the three measured values excluding the maximum value and the minimum value of the five measured values is defined as the contact angle of each solution.

Next, using the contact angles of the four types of solutions obtained, “the surface free energy (γ) of the solid, which is proposed by Hata et al., Is expressed as a dispersion force component (γ _S ^d ) and a polar force component (γ _S ^p ). , And a hydrogen bonding force component (γ _S ^h ), and a geometrical average method based on a formula (expanded Fowkes formula) obtained by extending the Fowkes formula ”, the polar force γp and the hydrogen bond strength described in the present invention γh is calculated. (Reference: Journal of Japan Adhesion Association, 1972, Vol. 8, No. 3, pp. 131-141)
Next, a specific calculation method is shown. When the tension is at the interface between the solid and the liquid, Formula (1) is established. The meaning of each symbol is as follows.

γ _S ^L : surface free energy of the known solution described in Table 1 and γ _S : surface free energy of the P2 layer γ _L : surface free energy of known solution described in Table 1 γ _S ^d : of the P2 layer Dispersive force component of surface free energy γ _S ^p : Polar force component of surface free energy of P2 layer γ _S ^h : Hydrogen bond force component of surface free energy of P2 layer γ _L ^d : Surface of known solution described in Table 1 Dispersion force component of free energy γ _L ^p : Polar force component of surface free energy of known solutions listed in Table 1 γ _L ^h : Hydrogen bond strength component of surface free energy of known solutions listed in Table 1 γ _S ^L = Γ _S + γ _L -2 (γ _S ^d · γ _L ^d ) ^1/2 -2 (γ _S ^p · γ _L p) ^1/2 -2 (γ _S ^h · γ _L ^h ) ^1/2 ... Formula (1).

Also, the state when the smooth solid surface is in contact with the liquid droplet at the contact angle (θ) is expressed by the following equation (Young's equation).

γ _S = γ _S ^L + γ _L cos θ (2)

When these mathematical formulas (1) and (2) are combined, the following formula is obtained.
_{^{_{^{(γ S d · γ L d}}}} ) 1/2 + (γ S p · γ L p) 1/2 + (γ S h · γ L h) 1/2 = γ L (1 + cosθ) / 2 ··· formula (3).

Actually, the four components of water, ethylene glycol, formamide, and diiodomethane have contact angles (θ) and the components of the surface tension of known solutions listed in Table 1 (γ _L ^d , γ _L ^p , γ _L ^h ) is substituted into Equation (3) to solve the four simultaneous equations. As a result, the surface free energy (γ), the dispersion force component (γ _S ^d ), the polar force component (γ _S ^p ), and the hydrogen bonding force component (γ _S ^h ) of the solid are calculated.
The dispersion force γd described in the present invention corresponds to the dispersion force component (γ _S ^d ), the polar force γp corresponds to the polar force component (γ _S ^p ), and the hydrogen bond force γh corresponds to the hydrogen bond force component (γ _S ^h ). To do.

(3) Component qualification of the P2 layer The component qualification of the P2 layer is the X2 photoelectron spectrometer (ESCA), Fourier infrared spectrophotometer (FT-IR) ATR method, time-of-flight secondary ion on the surface of the P2 layer. Mass spectrometer (TOF-SIMS) or P2 layer is dissolved and extracted with solvent, proton nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy ( ¹³ C-NMR), Fourier infrared spectrophotometry This is done by separating the total (FT-IR) or P2 layer and analyzing the structure by pyrolysis gas chromatography mass spectrometry (GC-MS). An analysis example using pyrolysis gas chromatography mass spectrometry (GC-MS) will be described below.

(3-1) Pyrolysis gas chromatography mass spectrometry (GC-MS)
First, the pyrolyzer PY-2010DD (frontier lab) and gas chromatograph GC-14AF (manufactured by Shimadzu Corporation) are used as the measuring device, the flame ionization detector (FID) is used as the detector, and the column Was used with a methyl silicone capillary column connected. Further, derivatization was performed with TMAH (tetramethylammonium hydroxide) as necessary.
(A) Urethane resin component When two types of diisocyanate compound and glycol compound are detected from the thermal decomposition product, it is assumed that the urethane resin component is contained in the P2 layer.
(B) Melamine resin component When a melamine compound is detected from a thermal decomposition product, melamine resin component shall be contained in P2 layer.
(C) Oxazoline resin component When the oxazoline compound is detected from the thermal decomposition product or when the ethanolamine structure is detected from the thermal decomposition product when derivatized with TMAH, the oxazoline resin component in the P2 layer Is assumed to be contained.

(4) Thickness of P2 layer Using a microtome, a small piece cut in a direction perpendicular to the surface of the laminate was prepared, and the cross section was measured with a field emission scanning electron microscope JSM-6700F (manufactured by JEOL Ltd.). The image was taken with a magnification of 10,000 times. From the cross-sectional photograph, the thickness of the P2 layer was calculated from the magnification. In addition, the thickness used the cross-sectional photograph of five places arbitrarily selected from the different measurement visual field, and used the average value.

(5) Adhesive evaluation with solar cell encapsulant (5-1) Initial adhesion with encapsulant Based on JIS K 6854-2 (1999), an EVA sheet which is an encapsulant for solar cell Adhesiveness was evaluated from the peel strength from the P2 layer side surface of the laminate. The measurement test piece is a 500 μm thick EVA sheet (vinyl acetate copolymerization ratio: 28 mol%) on a semi-tempered glass having a thickness of 3 mm, and the P2 layer side of the sheet of the example and the comparative example is the EVA sheet side. A layer obtained by press treatment using a commercially available vacuum laminator under conditions of a hot platen temperature of 145 ° C., a vacuum drawing of 4 minutes, a press of 1 minute, and a holding time of 10 minutes was used. The peel strength test is performed at 180 ° peel, the width of the test piece is 15 mm, two test pieces are prepared, the place is changed for each test piece, and three places are measured, and the average value of the obtained measurement values is peeled off The initial adhesion was determined as follows using the strength value. In addition, when the sheet | seat of this invention fractured | ruptured before peeling at an interface in this measurement, the measured value at the time of the fracture | rupture was made into the value of peeling strength.
When peel strength is 60.0N / 15mm or more: S
When the peel strength is 50.0 N / 15 mm or more and less than 60.0 N / 15 mm: A
When peel strength is 45.0 N / 15 mm or more and less than 50.0 N / 15 mm: B
When peel strength is 40.0 N / 15 mm or more and less than 45.0 N / 15 mm: C
When the peel strength is 30.0 N / 15 mm or more and less than 40.0 N / 15 mm: D
When peel strength is less than 30.0 N / 15 mm: E
S to D are good initial adhesion, and S is the best among them.

(5-2) Adhesion retention In the same manner as in (5-1) above, a measurement test piece was prepared, and the temperature was 120 ° C. and the relative humidity was measured with a pressure cooker (manufactured by Espec Corp.). The treatment was performed for 48 hours under the condition of 100% RH. Thereafter, the humidity was adjusted for 48 hours in an environment of a temperature of 27 ° C. and a humidity of 35% RH, and the peel strength after the acceleration test with the EVA sheet was measured in the same manner as in the section (5-1). Judged to.
When peel strength after acceleration test is 50.0 N / 15 mm or more: SS
When peel strength after acceleration test is 40.0 N / 15 mm or more and less than 50.0 N / 15 mm: S
When peel strength after accelerated test is 40.0 N / 15 mm or more and less than 45.0 N / 15 mm: A
When peel strength after acceleration test is 35.0 N / 15 mm or more and less than 40.0 N / 15 mm: B
When peel strength after accelerated test is 30.0 N / 15 mm or more and less than 35.0 N / 15 mm: C
When peel strength after accelerated test is 20.0 N / 15 mm or more and less than 30.0 N / 15 mm: D
When peel strength after accelerated test is less than 20 N / 15 mm: E
The adhesion retention is good in SS to D, and SS is the best among them.

(6) Moist heat resistance (measurement of elongation at break after wet heat test)
After the laminate was cut into a 10 mm × 200 mm shape of the measurement piece, it was processed for 48 hours under the conditions of temperature 125 ° C. and relative humidity 100% RH with a highly accelerated life tester pressure cooker (manufactured by Espec Corp.). After that, the elongation at break was measured based on ASTM-D882 (1997). Note that the measurement was performed between the chuck 50 mm, the pulling speed 300 mm / min, the number of measurements n = 5, and after measuring for each of the longitudinal direction and the width direction of the sheet, the average value was defined as the breaking elongation after the wet heat test. . From the elongation at break after the obtained wet heat test, the wet heat resistance was determined as follows.
When the breaking elongation after the wet heat test is 60% or more of the breaking elongation before the wet heat test: S
When the breaking elongation after the wet heat test is 40% or more and less than 60% of the breaking elongation before the wet heat test: A
When the breaking elongation after the wet heat test is 20% or more and less than 40% of the breaking elongation before the wet heat test: B
When the breaking elongation after the wet heat test is 10% or more and less than 20% of the breaking elongation before the wet heat test: C
When the breaking elongation after the wet heat test is less than 10% of the breaking elongation before the wet heat test: D
The wet heat resistance is good in A to C, and A is the best among them.

(7) UV resistance (color change during UV treatment test)
(7-1) Color tone (b value) measurement Based on JIS-Z-8722 (2000), a spectroscopic color difference meter SE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd., light source halogen lamp 12V4A, 0 ° to −45 °) The color tone (b value) of the surface on the P1 layer side of the laminate was measured at n = 3 by a reflection method using a post-spectral method.

(7-2) Color tone change Δb
With an i-super ultraviolet tester S-W151 (manufactured by Iwasaki Electric Co., Ltd.) so that the test light hits the P1 layer side surface of the laminate, the temperature is 60 ° C., the relative humidity is 60%, and the illuminance is 100 mW / cm ² (light source: The color tone (b value) before and after irradiation for 48 hours under the conditions of a metal halide lamp (wavelength range: 295 to 450 nm, peak wavelength: 365 nm) was measured according to the above item (8-1), and ultraviolet rays were obtained from the following equation (α). The change in color tone (Δb) after irradiation was calculated.
Color tone change after UV irradiation (Δb) = b1−b0 (α)
b0: Color tone before UV irradiation (b value)
b1: Color tone after UV irradiation (b value)
From the color tone change (Δb) before and after the obtained ultraviolet treatment test, ultraviolet resistance was determined as follows.
When the color change (Δb) before and after the ultraviolet irradiation treatment test is less than 1: A
When the color tone change (Δb) before and after the ultraviolet irradiation treatment test is 1 or more and less than 10: B
When the color change (Δb) before and after the ultraviolet irradiation treatment test is 10 or more and less than 20: C
When the color change (Δb) before and after the ultraviolet irradiation treatment test is 20 or more: D
The UV resistance is good in A to C, and A is the best among them.

(8) Solar cell characteristics (8-1) Production of solar cell Flux H722 from HOZAN was applied to the front and back silver electrode portions of solar cell Q6LPT-G2 from Qcells with a dispenser, and silver on the front and back surfaces. As a wiring material cut to a length of 155 mm on the electrode, the copper foil SSA-SPS0.2 × 1.5 (20) manufactured by Hitachi Cable Co., Ltd. is 10 mm away from one end of the cell on the surface side. The back side was placed symmetrically with the front side, and the soldering iron was contacted from the back side of the cell using a soldering iron, and the front and back sides were simultaneously soldered to produce one cell string.

Placed so that the longitudinal direction of the copper foil A-SPS 0.23 × 6.0 made by Hitachi Cable Co., Ltd. is perpendicular to the longitudinal direction of the wiring material protruding from the cell of the produced 1-cell string and the extraction electrode cut into 180 mm, The flux was applied to the portion where the wiring material and the take-out electrode overlapped, and solder welding was performed to produce strings with the take-out electrode.

Next, 190 mm × 190 mm 3.2 mm thick white plate heat-treated glass for solar cells manufactured by Asahi Glass Co., Ltd., 190 mm × 190 mm 500 μm thick EVA sheet (vinyl acetate copolymerization ratio: 28 mol%), prepared strings with extraction electrodes, 190 mm × A 190 mm 500 μm thick EVA sheet, a laminate cut into 190 mm × 190 mm, stacked in order so that the P2 layer side surface is located on the EVA side, and set the glass in contact with the hot platen of the vacuum laminator, Vacuum laminating was carried out under the conditions of a hot platen temperature of 145 ° C., vacuuming for 4 minutes, pressing for 1 minute, and holding time of 10 minutes. At this time, the strings with extraction electrodes were set so that the glass surface was on the cell surface side.

(8-2) Durability of Solar Cell Ten solar cells prepared in the above section (8-1) were prepared and treated for 4000 hr in a constant temperature and humidity chamber (manufactured by ESPEC Corporation) adjusted to 85 ° C. and 85% RH. Then, it was visually confirmed whether or not peeling occurred on the laminated solar cell back surface protection sheet. The durability of the solar cell was determined as follows by checking how many of the 10 solar cells had the sheet peeled off visually.
When peeling does not occur in all solar cells: A
When the sheet is peeled from one or more than four solar cells among the produced solar cells: B
When sheets are peeled from 4 or more and less than 8 solar cells among the produced solar cells: C
When 8 or more sheets of the produced solar cells are peeled from the solar cells: D
The durability of the solar cell is good from A to C, and among them, A is the best.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not necessarily limited thereto.

(Polyester resin material used for P1 layer)
1. PET raw material A (PET-A)
100 parts by mass of dimethyl terephthalate, 57.5 parts by mass of ethylene glycol, 0.03 parts by mass of magnesium acetate dihydrate, 0. 03 parts by mass were melted at 150 ° C. in a nitrogen atmosphere. While stirring this melt, the temperature was raised to 230 ° C. over 3 hours to distill methanol, and the transesterification reaction was completed. After completion of the transesterification reaction, an ethylene glycol solution (pH 5.0) in which 0.005 parts by mass of phosphoric acid was dissolved in 0.5 parts by mass of ethylene glycol was added. The intrinsic viscosity of the polyester composition at this time was less than 0.2.
Thereafter, the polymerization reaction was performed at a final temperature of 285 ° C. and a degree of vacuum of 0.1 Torr to obtain polyethylene terephthalate having an intrinsic viscosity of 0.52 and a terminal carboxyl group amount of 15 equivalents / ton. The obtained polyethylene terephthalate was dried and crystallized at 160 ° C. for 6 hours.
Thereafter, solid phase polymerization was performed at 220 ° C. and a vacuum degree of 0.3 Torr for 8 hours to obtain polyethylene terephthalate (PET-A) having an intrinsic viscosity of 0.80 and a terminal carboxyl group amount of 10 equivalents / ton. The obtained polyethylene terephthalate composition had a glass transition temperature of 82 ° C. and a melting point of 255 ° C.

2. PET raw material B (PET-B)
A polyethylene terephthalate (PET-B) having an intrinsic viscosity of 0.79 and a terminal carboxyl group content of 15 equivalents / ton was obtained except that the final temperature of the polymerization reaction was 290 ° C.

3. PET raw material C (PET-C)
A polyethylene terephthalate (PET-C) having an intrinsic viscosity of 0.85 and a terminal carboxyl group amount of 13 equivalents / ton was obtained except that the solid phase polymerization time was 10 hours.

4). PET raw material D (PET-D)
Except that the final temperature of the polymerization reaction was 295 ° C., the same procedure as for PET raw material A was carried out to obtain polyethylene terephthalate (PET-D) having an intrinsic viscosity of 0.77 and a terminal carboxyl group amount of 20 equivalents / ton.

5. PET raw material E (PET-E)
As a reaction catalyst, 0.03 parts by mass of manganese acetate tetrahydrate instead of magnesium acetate, and after completion of the transesterification, 0.005 parts by mass of phosphoric acid and 0.021 parts by mass of sodium dihydrogen phosphate dihydrate were added. Except that, polyethylene terephthalate (PET-E) having an intrinsic viscosity of 0.80 and a terminal carboxyl group amount of 10 equivalents / ton was obtained.

6). PET raw material F (PET-F)
A polyethylene terephthalate (PET-F) having an intrinsic viscosity of 0.75 and a terminal carboxyl group content of 28 equivalents / ton was obtained except that the final temperature of the polymerization reaction was 300 ° C.

7). PET raw material A base titanium oxide master 100 parts by mass of PET resin A (PET-A) obtained according to the above and 100 parts by mass of rutile-type titanium oxide particles having an average particle diameter of 210 nm were melt-kneaded in a vented 290 ° C. extruder, and a titanium oxide raw material (PETa -TiO ₂₎ was prepared.

8). PET raw material B-based titanium oxide master 2. 100 parts by mass of PET resin B (PET-B) obtained according to the above and 100 parts by mass of rutile titanium oxide particles having an average particle diameter of 210 nm were melt-kneaded in a vented 290 ° C. extruder, and a titanium oxide raw material (PETb -TiO ₂₎ was prepared.

9. PET raw material C-based titanium oxide master 2. 100 parts by mass of PET resin C (PET-C) obtained according to the above and 100 parts by mass of rutile-type titanium oxide particles having an average particle diameter of 210 nm were melt-kneaded in a vented 290 ° C. extruder to obtain a titanium oxide raw material (PETc -TiO ₂₎ was prepared.

10. 2. PET raw material C base terminal sealant master 100 parts by mass of PET resin C (PET-C) obtained according to the above and 10 parts by mass of Rhein Chemie's end-capping agent Stavacuxol P-400 were melt-kneaded in a vented 290 ° C. extruder and end-capped. A stopper material (PETc-CDI) was prepared.

11. PET raw material A base carbon particle master 100 parts by mass of PET resin A (PET-A) obtained according to the above and 25 parts by mass of carbon particles having an average particle diameter of 40 nm were melt-kneaded in a vented 290 ° C. extruder to obtain a carbon particle raw material (PETa-CB). Was made.

12 PET raw material D-based titanium oxide master 4. 100 parts by mass of PET resin D (PET-D) obtained according to the above and 100 parts by mass of rutile-type titanium oxide particles having an average particle diameter of 210 nm are melt-kneaded in a vented 290 ° C. extruder to obtain a titanium oxide raw material (PETd -TiO ₂₎ was prepared.

13 PET raw material E-based titanium oxide master 4. 100 parts by mass of PET resin E (PET-E) obtained according to the above and 100 parts by mass of rutile titanium oxide particles having an average particle diameter of 210 nm were melt-kneaded in a vented 290 ° C. extruder to obtain a titanium oxide raw material (PETe). -TiO ₂₎ was prepared.
(Resin component used for P2 layer)
1. Polyester (A)
Reaction in which 50 parts by mass of terephthalic acid, 50 parts by mass of isophthalic acid, 50 parts by mass of ethylene glycol, and 30 parts by mass of neopentyl glycol were purged with nitrogen together with 0.3 parts by mass of antimony trioxide as a polymerization catalyst and 0.3 parts by mass of zinc acetate. A polyester glycol was obtained by charging into a vessel and carrying out a polymerization reaction at 190 to 220 ° C. for 12 hours under normal pressure while removing water. Next, 5 parts by mass of 5-sodium sulfoisophthalic acid and xylene as a solvent were charged into the reactor to the polyester glycol obtained, and polymerization was performed for 3 hours while distilling off xylene at 260 ° C. under a reduced pressure of 0.2 mmHg. To obtain a polyester resin component. This polyester resin component was dissolved in water containing ammonia water and butyl cellosolve to obtain a coating solution containing polyester (A).

2. Acrylic modified polyester (A)
A total of 50 parts by mass of acrylic resin components of 40 parts by mass of methyl methacrylate and 10 parts by mass of methacrylamide are as follows: It added so that it might become a mass ratio of acrylic resin component / polyester resin component = 50/50 in the water dispersion containing polyester (A) obtained by this term. Further, 5 parts by mass of benzoyl peroxide was added as a polymerization initiator, and a polymerization reaction was carried out at 70 to 80 ° C. for 3 hours in a nitrogen purged reactor to obtain a coating liquid containing acrylic modified polyester (A).

3. Acrylic modified polyester (B)
50 parts by mass of a total of 50 parts by mass of acrylic resin components of 40 parts of 2-hydroxyethyl methacrylate and 10 parts of glycidyl methacrylate. It added so that it might become a mass ratio of acrylic resin component / polyester resin component = 50/50 in the water dispersion containing polyester (A) obtained by this term. Further, 0.1 part of 2,2'-azobis- (amidinopropane) dihydrochloride as a polymerization initiator was added, and the polymerization reaction was carried out at 70 to 80 ° C. for 3 hours in a nitrogen purged reactor. A coating solution containing (B) was obtained.

4). Urethane (A)
In a four-necked flask equipped with a reflux condenser, a nitrogen inlet tube, a thermometer, and a stirrer, 70 parts by mass of isophorone diisocyanate as a polyisocyanate compound, 15 parts by mass of an ethylene oxide addition diol of bisphenol A as a polyol compound, and diethylene glycol 15 parts by mass, 60 parts by mass of acetonitrile and 30 parts by mass of N-methylpyrrolidone were charged as a solvent. Next, under a nitrogen atmosphere, the temperature of the reaction solution was adjusted to 75 to 80 ° C., and 0.06 parts by mass of stannous octylate as a reaction catalyst was added and reacted for 7 hours. Subsequently, this was cooled to 30 degreeC and the isocyanate group terminal polyether urethane resin was obtained. Next, to a reaction vessel equipped with a homodisper capable of high-speed stirring, water was added and adjusted to 25 ° C., and an isocyanate group-terminated polyether urethane resin was added and dispersed in water while stirring and mixing at 2000 rpm. Then, the coating liquid containing the urethane resin (A) which consists of polyether urethane resin was prepared by removing a part of acetonitrile and water under reduced pressure.

5. Urethane (B)
4). In the same manner, 70 parts by mass of toluene diisocyanate as the polyisocyanate compound, 30 parts by mass of 1,6-hexanediol, 10 parts by mass of neopentyl glycol, 60 parts by mass of sebacic acid and 0.00001 part of tetrabutyl titanate as the polyol compound. A urethane comprising a polyester urethane resin obtained by reacting 28 parts by mass of a polyester polyol obtained by reacting at 220 ° C. for 24 hours under a nitrogen stream and 2 parts by mass of 1,4-butanediol as a chain extender. A coating liquid containing the resin (B) was prepared.

6). Urethane (C)
DIC Corporation polycarbonate urethane resin coating solution Hydran WLS-213 was used.

7). Melamine A melamine resin coating solution Nikalac MW12LF manufactured by Sanwa Chemical Co., Ltd. was used.

8). Oxazoline Oxazoline resin coating solution Epocros WS-500 manufactured by Nippon Shokubai Co., Ltd. was used.

(Coating composition for forming the P2 layer)
Using pure water as a diluent solvent, the total solid content in the coating composition is 17% by mass, and the components of each coating composition forming the P2 layer are solid parts by weight described in the table. In addition, after mixing the resin component of the P2 layer produced by the method described in the previous section, a surfactant plus coat RY-2 manufactured by Kyoyo Chemical Industry Co., Ltd. was added in an amount of 0.06% by mass with respect to the weight of each coating agent. The coating composition which mix | blends so that it may become a ratio and forms P2 layer was prepared. All of the obtained coating compositions were stored in an environment of 28 ° C. and applied to the P1 layer within 2 days after preparation.

(Example 1)
PET raw material A (PET-A) and PET raw material A-based titanium oxide master (PETa-TiO ₂ ), which were vacuum-dried at 180 ° C. for 2 hours, were prepared so that the amount of particles was the concentration shown in the table, and then placed in an extruder at 280 ° C. It was melt-kneaded and introduced into a T die die. Subsequently, it was melt-extruded into a sheet form from a T-die die and adhered and cooled and solidified by an electrostatic application method on a drum maintained at a surface temperature of 25 ° C. to obtain an unstretched sheet.
Subsequently, after preheating the unstretched sheet with a roll group heated to a temperature of 80 ° C., a three-fold speed difference is created between the roll heated to a temperature of 88 ° C. and the roll adjusted to a temperature of 25 ° C. After stretching 3 times in the longitudinal direction (longitudinal direction), it was cooled with a roll group at a temperature of 25 ° C. to obtain a uniaxially stretched sheet.
Next, after the corona treatment was applied to the uniaxially stretched sheet, the coating composition for forming the P2 layer prepared so as to have the weight ratio shown in the table according to the previous section was applied with a # 8 metalling bar.
Further, while holding the both ends of the obtained uniaxially stretched sheet with clips, it is led to a preheating zone set at a temperature of 80 ° C. in the tenter, and subsequently perpendicularly to the longitudinal direction in a heating zone kept at 90 ° C. The film was stretched 3.5 times in one direction (width direction). Subsequently, it was led to a heat treatment zone in the tenter, subjected to heat treatment at 220 ° C. for 20 seconds, and further subjected to a relaxation treatment of 4% in the width direction at 220 ° C. Then, it was gradually cooled gradually to form a laminate having an overall thickness of 125 μm.

When the P1 layer was separated from the obtained laminate and the polymer properties were measured, as shown in the table, the intrinsic viscosity IV was 0.68 dl / g, the amount of terminal carboxyl groups was 15 equivalents / ton, and the P1 layer contained Mg element. Contained 33 ppm and Sb element contained 241 ppm. When the characteristics of the P2 layer were evaluated, the surface energy was 7.9 mN / m in polar force, 3.8 mN / m in hydrogen bonding force, and the thickness was 0.6 μm.

The obtained laminate was evaluated for adhesion to the solar cell encapsulant. As a result, as shown in the table, it was found that the laminate had very excellent initial adhesion and adhesion retention. Moreover, it was found that the obtained laminate had excellent heat and heat resistance as a solar cell back surface protection sheet and good ultraviolet resistance, and the mounted solar cell had excellent durability.

(Examples 2 to 5)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the polyester resin component of the P1 layer was changed. At this time, only in Example 5, the torque of the extruder increased during the extrusion, but it was in the range where there was no problem. Moreover, the polymer characteristic of P1 layer of the obtained laminated body and the characteristic of P2 layer were as Table.

As shown in the table, the adhesion of the obtained laminate to the solar cell encapsulant was excellent as compared to Example 1, although the initial adhesion decreased as the amount of terminal carboxyl groups in the P1 layer increased. . In addition, the adhesion retention was in a favorable range, although it decreased with changes in the amount of terminal carboxyl groups in the P1 layer as compared with Example 1. Moreover, although the heat-and-moisture resistance as a solar cell back surface protection sheet fell with the increase in the amount of terminal carboxyl groups of the P1 layer, it was a good range, and the durability of the solar cell also decreased with the increase in the amount of terminal carboxyl groups of the P1 layer. Was in a good range.

(Examples 6 to 20)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the content of the resin component contained in the P2 layer was changed. The polymer properties of the P1 layer and the properties of the P2 layer of the obtained laminate are as shown in the table, and the surface energy of the P2 layer changed depending on the resin component contained in the P2 layer and its content.

As shown in the table, the adhesion of the obtained laminate to the solar cell encapsulant decreased with changes in the surface energy of the P2 layer as compared with Example 1, but the initial adhesion and adhesion retention were good. It was in range. The durability of the solar cell was also in a good range although it decreased with the change in the surface energy of the P2 layer.

(Examples 21 and 22)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the metabar during coating was changed and the thickness of the P2 layer was changed. At this time, in Example 23, coating unevenness was confirmed on the P2 surface of the laminate, but it was in a range where there was no problem. The polymer properties of the P1 layer and the properties of the P2 layer of the obtained laminate are as shown in the table, and the surface energy of the P2 layer changed as the thickness of the P2 layer was reduced.

As shown in the table, the adhesion of the obtained laminate to the solar cell encapsulant decreased with a decrease in the thickness of the P2 layer as compared to Example 1, but the initial adhesion and adhesion retention were in a good range. Met. The durability of the solar cell was also in a good range although it decreased with the change in the surface energy of the P2 layer.

(Examples 23 to 25)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the configuration of the P1 layer and the polyester resin component were changed. For Example 25, the PET raw material A (PET-A) and the PET raw material A-based titanium oxide master (PETa-TiO ₂ ) were mixed in the P1 layer separately so that the P11 layer and the P12 layer had the particle amounts shown in the table. The raw materials previously prepared were melted and kneaded separately by two extruders, introduced into the T die die from the two extruders via a feed block, and a P11 / P12 laminated sheet was obtained. Similarly, a sheet was obtained. At this time, the screw speed of the two extruders was adjusted so that the stacking ratio of P11 / P12 was 5/1, and the P2 layer was prepared by coating on the P11 layer side. The properties of the P1 layer and the P2 layer of the obtained laminate are as shown in the table. It was found that Example 23 contained 69 ppm of Mn element and 29 ppm of Na element in the P1 layer.

The adhesion of the obtained laminate to the solar cell encapsulant was found to be a laminate having very excellent initial adhesion and adhesion retention as shown in the table. Among them, Example 23 is a laminate having particularly excellent adhesion retention, and the moisture and heat resistance as a solar cell back surface protection sheet is very superior to that of Example 1, and Examples 24 and 25 are back surfaces of solar cells. It was found that the ultraviolet resistance as a protective sheet was superior to that of Example 1. Further, it was found that the durability of the solar cell was very excellent as in Example 1.

(Comparative Example 1)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the polyester resin component of the P1 layer was changed. When P1 layer was isolate | separated from the obtained laminated body and the polymer characteristic was measured, the amount of terminal carboxyl groups was 35 equivalent / tons as Table.

As shown in the table, the adhesion of the obtained laminate to the solar cell encapsulant was very good initial adhesion, but it was found to be a laminate having poor adhesion retention. Moreover, it turned out that it is similarly inferior also about the durability of a solar cell.

(Comparative Examples 2 to 9)
As described in the table, a laminate was obtained in the same manner as in Example 1 except that the content of the resin component contained in the P2 layer was changed. The properties of the P2 layer of the obtained laminate are as shown in the table, and the above requirement (1) Polar force γp is 4.8 mN / m or more and 21.0 mN / m or less, and / or (2) Polar force γp and hydrogen It was found that the difference γp−γh in the binding force γh deviates from 1.0 mN / m to 20.0 mN / m.

As shown in the table, the adhesion of the obtained laminate to the solar cell encapsulant decreases with changes in the surface energy of the P2 layer, and it is found that the laminate is inferior in initial adhesion and / or adhesion retention. It was. Moreover, it turned out that it is similarly inferior also about the durability of a solar cell.

The laminate of the present invention is excellent in adhesion to EVA that is a sealing material for solar cells, and adhesion retention, and is used not only for solar cell back surface protection sheets but also for industrial materials such as process sheets and adhesive tapes and extrusion. It can be suitably used as an easy-adhesive substrate application such as laminating or heat laminating. Moreover, the solar cell excellent in durability can be provided by mounting this laminated body in a solar cell.

1: Solar cell back surface protection sheet 2: Sealing material 3: Power generation element 4: Transparent substrate 5: Surface on the sealing material 2 side of the solar cell backsheet 6: On the side opposite to the sealing material 2 of the solar cell backsheet surface

Claims

It has the base material layer (P1 layer) which has the polyester resin whose terminal carboxyl group amount is 25 equivalent / tons or less as a main component, and an easily bonding layer (P2 layer), The said P2 layer has the following requirements (1) and The laminated body characterized by satisfying (2).
(1) Polar force γp is 4.8 mN / m or more and 21.0 mN / m or less (2) Difference γp−γh between polar force γp and hydrogen bonding force γh is 1.0 mN / m or more and 20.0 mN / m or less
The layered product according to claim 1, wherein hydrogen bond strength γh of the P2 layer is 1.0 mN / m or more and 4.5 mN / m or less.
The laminate according to claim 1 or 2, wherein the P2 layer contains three components of a urethane resin component, a melamine resin component, and an oxazoline resin component.
4. The laminate according to claim 3, wherein the urethane resin component contained in the P2 layer has an alicyclic structure.
The laminate according to claim 3 or 4, wherein the P2 layer further contains a polyester resin component.
6. The laminate according to claim 5, wherein the polyester resin component contained in the P2 layer is an acrylic-modified polyester resin component.
The P2 layer is a layer formed from a coating composition containing a urethane resin, a melamine resin, and an epoxy resin. In the coating composition, the urethane resin contains 10% by mass or more and 40% by mass or less in terms of solid weight. The melamine resin is contained in an amount of 1% by mass to 20% by mass in terms of solid content, and the oxazoline resin is contained in an amount of 1% by mass to 25% by mass in terms of solid content. The laminated body in any one.
The laminate according to any one of claims 1 to 7, wherein the P1 layer contains Mn element and Na element.
A solar cell back surface protection sheet using the laminate according to any one of claims 1 to 8.
A solar cell on which the laminate according to any one of claims 1 to 8 is mounted.