CN103717631A

CN103717631A - Sealant

Info

Publication number: CN103717631A
Application number: CN201280036881.1A
Authority: CN
Inventors: 荒井亨; 梅山雅也; 见山彰; 塚本步
Original assignee: Denki Kagaku Kogyo KK
Current assignee: Denka Co Ltd
Priority date: 2011-08-03
Filing date: 2012-08-01
Publication date: 2014-04-09
Also published as: TW201329111A; KR101922279B1; JP6073787B2; WO2013018839A1; JPWO2013018839A1; KR20140064811A

Abstract

The invention provides a novel thermoplastic sealant resin which, as a next-generation solar battery sealant, has excellent mechanical properties, transparency, heat resistance, electrical insulation properties, damp-proofing properties, softness and sealing properties, and is suitable as a thin-layered sealant for example, and also provided is a sheet. The present invention provides a sealant resin which mainly comprises a cross copolymer (hereinafter referred to simply as the cross copolymer) formed mainly of an aromatic polyene unit, an ethylene unit, and an aromatic vinyl compound unit obtained by a predetermined manufacturing method, and said sealant resin having excellent mechanical properties, transparency, heat resistance, electrical insulation properties, damp-proofing properties, softness and sealing properties, and the present invention also provides a sheet.

Description

Packaging material

Technical Field

The present invention relates to a sealing material containing a resin as a main component.

Prior Art

In recent years, solar cells (solar power generation devices) that directly convert sunlight into electric energy have been widely used and further development has been underway from the viewpoints of reduction in carbon dioxide emission, effective use of resources, prevention of environmental pollution, and the like. The solar cell is expected to have further improved reliability and significantly reduced manufacturing cost.

As shown in fig. 1, the solar cell is generally configured such that a plurality of solar cell cells D including a crystalline silicon power generation element and the like are sealed between a light-receiving-surface-side transparent protection member a such as a glass plate and a back-surface-side protection member (back sheet) B so as to be sandwiched between a light-receiving-surface-side sealing material C1 and a back-surface-side sealing material C2.

Such a solar cell is manufactured by laminating a light-receiving-side transparent protective member a, a light-receiving-side sealing material C1, a solar cell unit D, a back-side sealing material C2, and a back-side protective member B in this order, and heating and pressing the laminate to crosslink and cure the EVA sealing material, thereby bonding and integrating the components.

Since solar cells are used for a long period of time of 20 to 30 years under various temperature and humidity conditions and in outdoor environments where they are exposed to wind and rain, the materials used are required to have high reliability. Crosslinked EVA, which is widely used as a sealing material, is a material that is excellent in transparency and softness and has been used for a long time and has been in practical use (patent document 1), but has a problem in terms of securing reliability for a long period of time because it has a relatively high moisture permeability and a relatively low volume resistivity, and corrosive acetic acid is liberated by hydrolysis and decomposition. Further, because of these problems, it is necessary to have a sufficient thickness to ensure reliability, and it is difficult to make the package material thin.

When the EVA is modularized, crosslinking treatment is necessary to impart heat resistance, and there are problems such as productivity due to a long process time, deterioration of the crosslinking agent during storage of the crosslinked material, foaming during crosslinking, and crosslinking shrinkage of the sheet.

Therefore, a thermoplastic sealing material using a resin having heat resistance, high volume resistivity, and low moisture permeability, which does not require crosslinking, has been proposed. For example, various sealing materials using an ionomer resin (patent document 2), a polypropylene-based soft resin (patent document 3), and an ethylene- α -olefin copolymer (LLDPE: linear low-density polyethylene) (patent documents 4,5, and 6) have been proposed.

On the other hand, an encapsulating material using a cross copolymer (cross copolymer) using styrene and ethylene as raw materials has been proposed (patent document 8). The sealing material is excellent in transparency, weather resistance, electrical insulation and moisture resistance and has softness equivalent to that of EVA.

Patent document 1: japanese patent No. 3473605

Patent document 2: japanese Kokai publication No. 2008-522877

Patent document 3: WO06/057361 publication

Patent document 4: japanese patent laid-open No. 2007 and 318008

Patent document 5: japanese laid-open patent publication No. 2010-254989

Patent document 6: japanese laid-open patent publication No. 2002-235048

Patent document 7: japanese laid-open patent application No. 2001-119047

Patent document 8: japanese laid-open patent application No. 2010-150442

Disclosure of Invention

However, the ionomer resin generally has a problem of inferior softness and moldability compared to EVA. An olefin-based soft resin containing polypropylene as a raw material has a problem in light resistance. When LLDPE is used, it is necessary to have a comonomer content (density) for securing a melting point of heat resistance of 100 to 120 ℃ which is heat resistance in use of a solar cell, but such LLDPE has a problem of insufficient softness and transparency. In addition, LLDPE with high comonomer content, low density, high transparency and high softness has a melting point of about 60 to 80 ℃, and as a solar cell encapsulating material, it has insufficient heat resistance. Accordingly, a technique for imparting heat resistance by crosslinking or pseudo-crosslinking by irradiation with a peroxide, vinylsilanes, or an electron beam has been disclosed (patent documents 5,6, and 7). However, this requires a complicated operation and involves the aforementioned disadvantages associated with crosslinking.

The encapsulating material is required to have softness (cushioning property) and sealing property for protecting a silicon unit which is easily broken in a use environment or in manufacturing a solar cell. Furthermore, in recent years, attempts have been made to reduce the cost of solar cell modules by, for example, further reducing the thickness of the crystal or polycrystalline silicon cell, and the encapsulating material is required to have higher softness and encapsulation performance than ever before. On the other hand, the thickness of the encapsulating material is required to be further reduced in order to reduce the cost, but it is difficult to reduce the thickness in order to secure the softness. Further, as described above, EVA has low electrical insulation and moisture resistance, and thus it is more difficult to make the EVA thinner.

The present invention provides a novel thermoplastic sealing material resin which is excellent in mechanical properties, transparency, heat resistance, electrical insulation, moisture resistance, softness and sealing properties as a new generation of solar cell sealing material and is suitable as a thin-layer sealing material, for example, and a sheet thereof.

The present invention relates to a sealing material resin which mainly contains a cross copolymer mainly composed of an aromatic vinyl compound unit, an ethylene unit and an aromatic polyene unit (hereinafter simply referred to as a cross copolymer) obtained by a specific production method, and which is excellent in mechanical properties, transparency, heat resistance, electrical insulation, moisture resistance, softness and sealing properties, and a sheet thereof.

The present invention relates to a sealing resin and a sheet thereof, which are a sealing resin containing a cross-copolymer obtained by a production method comprising the steps of: a coordination polymerization step of copolymerizing a vinyl monomer, an aromatic vinyl compound monomer, and an aromatic polyene using a single-site coordination polymerization catalyst to synthesize a vinyl-aromatic vinyl compound-aromatic polyene copolymer macromonomer having an aromatic vinyl compound unit content of 17 to 30 mol%, an aromatic polyene unit content of 0.01 to 0.2 mol%, and the balance being a vinyl unit content; and a polymerization step comprising an anionic polymerization step of polymerizing the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer using an anionic polymerization initiator in the coexistence of the aromatic vinyl compound monomer; the encapsulating material resin also satisfies the following conditions (1) to (3).

(1) The ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step has a weight average molecular weight of 3 to 15 ten thousand and a molecular weight distribution (Mw/Mn) of 1.8 to 4.

(2) The heat of crystal fusion (Δ H) of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer observed at 0 to 150 ℃ is 30J/g or less.

(3) The mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer unit in the cross copolymer obtained in the anionic polymerization step is 75 to 95 mass%.

In the present invention, the term "encapsulant resin mainly containing a cross-copolymer and a sheet thereof (hereinafter, may be simply referred to as an encapsulant or an encapsulant sheet) means that the mass ratio of the cross-copolymer in the encapsulant resin and the sheet thereof is at least 70 mass% or more and 99.9 mass% or less, and more preferably 95 mass% or more and 99.9 mass% or less.

The encapsulating resin mainly containing a cross copolymer and the sheet thereof of the present invention are characterized by being excellent in softness and transparency, and the a hardness is 50 or more and less than 70, preferably 50 or more and less than 65, most preferably 50 or more and less than 63, and the total light transmittance (0.5mm thick sheet) is 85% or more. The sealing resin and the sheet thereof containing the cross-linked copolymer contain a light stabilizer which captures radicals generated by the action of light and, if necessary, an ultraviolet absorber which converts light energy into harmless heat energy.

The sealing resin and the sheet thereof mainly comprising the cross-copolymer of the present invention may contain various other additives commonly used in sealing materials, i.e., a light-resistant agent, an antioxidant (aging inhibitor), a silane coupling agent, a crosslinking agent if necessary, a crosslinking aid if necessary, and the like.

A novel encapsulating material which is excellent in transparency, heat resistance, electrical insulating properties, moisture resistance, softness and encapsulating properties and suitable as a thin encapsulating material for a solar cell of a new generation.

Drawings

Fig. 1 shows a cross-sectional view of a typical solar cell.

Fig. 2 shows the results of the durability test (DH test) of the solar cell module in the test.

Detailed Description

The sealing resin mainly containing a cross-copolymer of the present invention and the sheet thereof are specifically used as the sealing material C1 and/or C2 shown in fig. 1.

The present invention relates to a sealing resin and a sheet thereof, which are a sealing resin containing a cross-copolymer obtained by a production method comprising the steps of: a coordination polymerization step of copolymerizing a vinyl monomer, an aromatic vinyl compound monomer and an aromatic polyene using a single-site coordination polymerization catalyst to synthesize a vinyl-aromatic vinyl compound-aromatic polyene copolymer macromonomer having an aromatic vinyl compound unit content of 17 to 30 mol%, an aromatic polyene unit content of 0.01 to 0.2 mol%, and a vinyl unit content as the remainder; and a polymerization step comprising an anionic polymerization step of polymerizing the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer using an anionic polymerization initiator in the coexistence of the aromatic vinyl compound monomer; and satisfies the following conditions.

The composition of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer can be controlled within the above range by using a well-known conventional method, and can be most simply achieved by changing the monomer addition composition ratio and changing the ethylene partial pressure.

When the content of the aromatic vinyl compound unit in the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step is less than 17 mol%, crystallization occurs due to the structure of the ethylene chain, and the heat of crystal fusion increases, resulting in deterioration of softness and transparency. When the content of the aromatic vinyl compound unit is more than 30 mol%, the finally obtained cross-copolymer may have a high glass transition temperature, poor low-temperature characteristics, or deteriorated softness at room temperature, which is not preferable.

When the content of the aromatic polyene unit in the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step is 0.01 to 0.2 mol%, a cross copolymer excellent in transparency and moldability can be obtained. When the content of the aromatic polyene unit is less than 0.01 mol%, the production efficiency of the cross copolymer is lowered and the proportion of a mixture (non-compatible) of the main chain ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and the aromatic vinyl compound polymer is increased, resulting in lowering of transparency. When the content of the aromatic polyene unit is more than 0.2 mol%, the molding processability (MFR) of the resulting cross copolymer is lowered, and a gel component is easily formed.

When the weight average molecular weight of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer is more than 15 ten thousand, the transparency of the cross copolymer may be reduced, and when it is less than 3 ten thousand, the mechanical properties may be reduced. The weight average molecular weight can be controlled by a known method, and can be usually controlled by appropriately changing the polymerization temperature in the coordination polymerization step.

When the crystal structure derived from the ethylene chain structure is present to some extent or more, the softness and transparency may be impaired, and the dimensional stability of the molded article may be impaired by shrinkage or the like caused by crystallization during molding. The total heat of fusion of the cross-copolymer obtained according to the present invention, which includes the crystallinity of the olefin and the crystallinity of the other elements, is 30J/g or less, preferably 20J/g or less. The total crystal melting heat can be determined by summing up peak areas derived from melting points observed in the range of 0 ℃ to 150 ℃ by DSC (Differential scanning calorimetry).

(3) The mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer in the cross copolymer obtained through the anionic polymerization step is 75 to 95 mass%, more preferably 80 to 95 mass%. When the mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer is less than 75% by mass, the softness decreases and the a hardness may exceed 70. When the mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer is more than 95% by mass, the contribution of the aromatic vinyl compound polymer is reduced, resulting in a decrease in the heat resistance of the cross copolymer. The a hardness of the cross copolymer obtained by the production method is 50 or more and less than 70, preferably 50 or more and less than 65, and most preferably 50 or more and less than 63. The mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step can be controlled by, for example, monitoring the ethylene consumption amount, the polymer concentration and the composition during the polymerization and estimating the mass of the copolymer produced in the polymerization step. In order to decrease the mass ratio, for example, the anionic polymerization step may be started early by calculating the mass of the produced copolymer while the above monitoring is performed and shortening the time of the coordination polymerization step, or the start of the anionic polymerization step may be delayed by increasing the polymerization time in order to increase the mass ratio. Further, an anionic polymerizable vinyl compound monomer used in the anionic polymerization step may be added at the start of the anionic polymerization step or during the anionic polymerization step. The mass ratio of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step can be arbitrarily changed depending on the additional amount of the anionic polymerizable vinyl compound monomer.

It is considered that the cross copolymer obtained by this method has a structure (cross-copolymerized structure or segmented star copolymer structure) in which a polymer chain composed of an anionic polymerizable monomer, which is a cross chain, is bonded to an ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer, which is a main chain, via a main chain aromatic polyene unit. However, the structure and the content ratio of the cross-copolymer are arbitrary, and the cross-copolymer of the present invention is defined as a copolymer (polymer) obtained by the production method of the present invention.

The method for producing the cross copolymer used in the present invention will be described in detail below.

< coordination polymerization Process >

In the coordination polymerization step of the present production method, a single-site coordination polymerization catalyst is used. A single-site coordination polymerization catalyst comprising a transition metal compound represented by the following general formula (1) or (6) and a cocatalyst is preferably used.

Wherein A, B may be the same or different and is a group selected from an unsubstituted or substituted benzoindenyl group, an unsubstituted or substituted cyclopentadienyl group, an unsubstituted or substituted indenyl group, or an unsubstituted or substituted fluorenyl group. The substituted benzindenyl group, substituted cyclopentadienyl group, substituted indenyl group, or substituted fluorenyl group means a benzindenyl group, cyclopentadienyl group, indenyl group, or fluorenyl group in which 1 or more hydrogen atoms that may be substituted are substituted with an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, a halogen atom, an OSiR3 group, a SiR3 group, or a PR2 group (R represents a hydrocarbon group having 1 to 10 carbon atoms).

It is preferable that A, B in the formula are the same or different, and at least one of A, B is a group selected from unsubstituted or substituted benzoindenyl represented by the general formula (2), (3), (4), and unsubstituted or substituted indenyl represented by the general formula (5). Most preferably A, B in the formula may be the same or different, and A, B each represents a group selected from unsubstituted or substituted benzoindenyl represented by the general formula (2), (3), (4), and unsubstituted or substituted indenyl represented by the general formula (5).

In the following general formulae (2), (3) and (4), R1 to R3 are each hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, a halogen atom, an OSiR3 group, a SiR3 group or a PR2 group (R each represents a hydrocarbon group having 1 to 10 carbon atoms). R1, R2 and R3 may be the same or different, and the adjacent R1 and R2 groups may be integrated to form an aromatic ring or an aliphatic ring having 5 to 8-membered rings.

Examples of the unsubstituted benzoindenyl group represented by the above general formula include 4, 5-benzo-1-indenyl (also referred to as benzo (e) indenyl), 5, 6-benzo-1-indenyl, and 6, 7-benzo-1-indenyl, and examples of the substituted benzoindenyl group include α -acenaphtho-1-indenyl, 3-cyclopenta [ c ] phenanthryl, and 1-cyclopenta [ l ] phenanthryl.

In the general formula (5), R4 is hydrogen, alkyl group having 1 to 20 carbon atoms, aryl group having 6 to 10 carbon atoms, alkylaryl group having 7 to 20 carbon atoms, halogen atom, OSiR3 group, SiR3 group or PR2 group (R represents hydrocarbon group having 1 to 10 carbon atoms). R4 may be the same or different from each other.

Examples of the unsubstituted indenyl group represented by the above general formula include a 1-indenyl group, and examples of the substituted indenyl group include a 4-methyl-1-indenyl group, a 5-ethyl-1-indenyl group, a 4-phenyl-1-indenyl group and a 4-naphthyl-1-indenyl group.

More preferably, A, B in the formula may be the same or different and each is a group selected from the group consisting of an unsubstituted or substituted benzoindenyl group represented by the general formulae (2), (3) and (4) and an unsubstituted or substituted indenyl group represented by the general formula (5).

Y is a methylene group, a silylene group, an ethylene group, a germylene group or a boron group bonded to A, B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms as a substituent (the substituent may further contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms or silicon atoms). The substituents may be the same or different from each other. Further, Y may have a cyclic structure. Y is preferably a methylene group or a boron group bonded to A, B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms as a substituent (the substituent may further contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, or silicon atoms).

X is hydrogen, hydroxyl, halogen, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, or an amide group having a hydrocarbon substituent having 1 to 20 carbon atoms. 2 xs may be bonded. M is zirconium, hafnium, or titanium.

In addition, the present transition metal compound is preferably a racemate. Preferable examples of such transition metal compounds include transition metal compounds having a cross-linked structure with a substituted methylene group as specifically exemplified in EP-0872492A2, Japanese patent application laid-open Nos. 11-130808 and 9-309925, and transition metal compounds having a cross-linked structure with a boron group as specifically exemplified in WO 01/068719. In addition, a transition metal compound represented by the following general formula (6) can also be preferably used.

Wherein Cp is a group selected from the group consisting of unsubstituted or substituted cyclopentaphenanthreneyl, unsubstituted or substituted benzindenyl, unsubstituted or substituted cyclopentadienyl, unsubstituted or substituted indenyl, and unsubstituted or substituted fluorenyl. The substituted cyclopentaphenanthreneyl, substituted benzindenyl, substituted cyclopentadienyl, substituted indenyl, or substituted fluorenyl is a cyclopentaphenanthreneyl, benzindenyl, cyclopentadienyl, indenyl, or fluorenyl group in which 1 or more hydrogen atoms that may be substituted is substituted with an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, a halogen atom, an OSiR3 group, a SiR3 group, or a PR2 group (R represents a hydrocarbon group having 1 to 10 carbon atoms).

Y' is a methylene group, a silylene group, an ethylene group, a germylene group, or a boron group bonded to Cp or Z and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms. The substituents may be the same or different from each other. In addition, Y' may have a cyclic structure.

Z is a group containing a nitrogen atom, an oxygen atom or a sulfur atom, bonded to Y 'through a ligand coordinated to M' by the nitrogen atom, the oxygen atom or the sulfur atom, and having hydrogen or a substituent having 1 to 15 carbon atoms.

M' is zirconium, hafnium, or titanium.

X' is a dialkylamide group having hydrogen, halogen, an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 8 to 12 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkyl substituent having 1 to 6 carbon atoms.

n is an integer of 1 or 2.

Transition metal compounds represented by the general formula (6) are described in WO99/14221, EP416815 and US 6254956.

In the coordination polymerization step of the present production method, it is more preferable to use a single-site coordination polymerization catalyst comprising the transition metal compound represented by the above general formula (1) and a co-catalyst. As the co-catalyst used in the coordination polymerization step of the present production method, a known co-catalyst used in combination with a conventional transition metal compound can be used. As such a cocatalyst, an aluminoxane or boron compound such as METHYLALUMINOXANE (or Methylalumininoxane or MAO) is preferably used. If necessary, an alkyl aluminum such as triisobutylaluminum or triethylaluminum may be used in combination with an aluminoxane or a boron compound. Examples of such a cocatalyst include cocatalysts and alkylaluminum compounds described in EP-0872492A2, Japanese patent application laid-open No. 11-130808, Japanese patent application laid-open No. 9-309925, WO00/20426, EP0985689A2 and Japanese patent application laid-open No. 6-184179.

The cocatalyst such as aluminoxane is used in a ratio of 0.1 to 100000, preferably 10 to 10000, in terms of aluminum atom/transition metal atom ratio, relative to the metal of the transition metal compound. When the amount is 0.1 or more, the transition metal compound can be efficiently activated, and when the amount is 100000 or less, the method is economically advantageous.

Furthermore, the transition metal compound of the most preferred single-site coordination polymerization catalyst used has a structure represented by the general formula (1) and A, B may be the same or different, A, B represents a methylene group or a boron group which is selected from unsubstituted or substituted benzoindenyl groups and unsubstituted or substituted indenyl groups, and Y is a hydrocarbon group or a boron group which is bonded to A, B and has hydrogen or a hydrocarbon group having 1 to 15 carbon atoms as a substituent (may contain 1 to 3 nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms or silicon atoms), and the transition metal compound is a racemic body. When this condition is satisfied, the obtained ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer having the composition in the range of the present invention has isotactic stereoregularity in the alternating structure of olefin-aromatic vinyl compound, preferably in the alternating structure of ethylene-aromatic vinyl compound, and therefore, the cross copolymer of the present invention can have microcrystallinity derived from the alternating structure. In addition, the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer can impart good mechanical properties and oil resistance based on the alternate structure microcrystallinity as compared with the case where no stereoregularity is present, and finally the cross copolymer of the present invention can also inherit this feature.

The ethylene-aromatic vinyl compound-aromatic polyene copolymer has a microcrystalline melting point of about 50 to 120 ℃ based on the alternating structure of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer, and a heat of crystal fusion of 40J/g or less, preferably 30J/g or less as determined by DSC. The cross-copolymer of the present invention can have a heat of crystal fusion of 40J/g or less, preferably 30J/g or less as a whole. The crystallinity having a crystal melting heat in the range is not detrimental to the softness and moldability of the present cross-copolymer, and is not advantageous in terms of excellent mechanical properties and oil resistance.

When a boron compound is used as the co-catalyst, the boron compound is used in a proportion of 0.01 to 100, preferably 0.1 to 10, particularly preferably 1, in terms of boron atom/transition metal atom ratio. When the amount is 0.01 or more, the transition metal compound can be efficiently activated, and when the amount is 100 or less, the method is economically advantageous. The transition metal compound and the cocatalyst may be mixed and prepared outside the polymerization apparatus, or may be mixed in the apparatus during the polymerization.

The aromatic vinyl compound used in the present invention includes styrene and various substituted styrenes, for example, p-methylstyrene, m-methylstyrene, o-tert-butylstyrene, m-tert-butylstyrene, p-chlorostyrene, o-chlorostyrene, and the like. Industrially, styrene, p-methylstyrene and p-chlorostyrene are preferably used, and styrene is particularly preferably used.

The aromatic polyene used in the present invention is an aromatic polyene having a carbon number of 10 to 30 inclusive, having a plurality of double bonds (vinyl groups) and one or more aromatic groups and being capable of coordination polymerization, and is an aromatic polyene in which the double bonds remaining in a state where 1 of the double bonds (vinyl groups) is used for coordination polymerization and polymerization are capable of anion polymerization. Preferably, a mixture of any 1 or 2 or more of o-divinylbenzene, p-divinylbenzene and m-divinylbenzene is suitably used.

In the case of producing an ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer in the coordination polymerization step of the present invention, the above-mentioned monomers, transition metal compound and cocatalyst are contacted with each other, but any known method can be used as the order of contacting and the contacting method.

The above-mentioned copolymerization method may be a method of polymerizing in a liquid monomer without using a solvent, or a method of using a saturated aliphatic or aromatic hydrocarbon or a halogenated hydrocarbon such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, ethylbenzene, xylene, chlorine-substituted benzene, chlorine-substituted toluene, methylene chloride, chloroform, or a mixed solvent thereof alone. Preferably, a mixed alkane solvent, cyclohexane, toluene, ethylbenzene, or the like is used. The polymerization form may be either solution polymerization or slurry polymerization. Further, as necessary, a known method such as batch polymerization, continuous polymerization, prepolymerization, multistage polymerization, or the like can be used.

It is also possible to use single, linked multiple tank polymerization vessels, single, linked multiple pipe polymerization plants of linear and loop type. The polymerization tank in the form of a pipe may have various known mixers such as a dynamic or static mixer and a static mixer having heat removal, and various known coolers such as a cooler having a narrow pipe for heat removal. In addition, a batch prepolymerization tank may be provided. Further, a method such as gas phase polymerization can also be used.

The polymerization temperature is preferably from-78 ℃ to 200 ℃. The polymerization temperature of-78 ℃ or higher is industrially advantageous, and at 200 ℃ or lower, it is suitable because the transition metal compound is not decomposed. Further, it is industrially preferably from 0 ℃ to 160 ℃, particularly preferably from 30 ℃ to 160 ℃.

The pressure during polymerization is preferably 0.1 to 100 atmospheres, more preferably 1 to 30 atmospheres, and particularly preferably 1 to 10 atmospheres industrially.

< anionic polymerization Process >

In the anionic polymerization step of the production method of the present invention, polymerization is carried out using an anionic polymerization initiator in the coexistence of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and the aromatic vinyl compound monomer obtained in the coordination polymerization step.

As the aromatic vinyl compound monomer, styrene, p-methylstyrene, p-tert-butylstyrene, p-chlorostyrene, α -methylstyrene, vinylnaphthalene, vinylanthracene, etc. are used, with styrene being most preferred. The aromatic vinyl compound monomer used in the anionic polymerization step and the aromatic vinyl compound used in the coordination polymerization step are preferably the same monomer, and more preferably, a part or all of them are unreacted aromatic vinyl compound monomers remaining in the polymerization solution obtained in the coordination polymerization step. In the anionic polymerization step of the present invention, in addition to the above-mentioned aromatic vinyl compound monomer, an aromatic polyene which is not polymerized in the coordination polymerization step and remains in a polymerization solution in a small amount may be polymerized.

The anionic polymerization step of the present invention is carried out after the above-mentioned coordination polymerization step. In this case, the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step can be separated and purified from the polymerization solution by any polymer recovery method such as a granulation (column) method, a steam stripping method, a direct solvent removal method using a devolatilization tank, a devolatilization extruder, or the like, and used in the anionic polymerization step. However, it is economically advantageous to use the residual olefin in the subsequent anionic polymerization step after or without reducing the pressure of the polymerization solution after the coordination polymerization. It is one of the features of the present invention that a polymerization solution containing a polymer may be used in the crossing step without separating the polymer from the polymerization solution.

The solvent used in the anionic polymerization step is preferably a mixed alkane solvent, such as cyclohexane and benzene, which does not cause defects such as chain transfer during anionic polymerization, and other solvents, such as toluene and ethylbenzene, can be used as long as the polymerization temperature is 150 ℃ or lower.

The polymerization form can be any of the well-known methods used in anionic polymerization.

The polymerization temperature is preferably from-78 ℃ to 200 ℃. The polymerization temperature of-78 ℃ or higher is industrially advantageous, and when it is 150 ℃ or lower, chain transfer or the like does not occur, so that it is preferable. Further, it is preferably from 0 ℃ to 200 ℃ in an industrial scale, and particularly preferably from 30 ℃ to 150 ℃.

In the anionic polymerization step of the present invention, a well-known anionic polymerization initiator can be used. Lithium salts or sodium salts of alkyllithium compounds, biphenyl, naphthalene, pyrene and the like are preferably used, and sec-butyllithium and n-butyllithium are particularly preferably used. In addition, a polyfunctional initiator, a dilithium compound, or a trilithium compound may be used. Further, a well-known anionic polymerization terminal coupling agent may be used as necessary.

When methylaluminoxane is used as a cocatalyst of the polymerization catalyst in the coordination polymerization step, the amount of the initiator is preferably not less than the equivalent of the oxygen atom contained therein, and particularly preferably not less than 2 equivalents. In the coordination polymerization process, when a boron compound is used as a co-catalyst of the polymerization catalyst, the amount of the initiator can be reduced because it is sufficiently small compared with the oxygen atom equivalent in methylaluminoxane.

In the anionic polymerization step, the length of the crosslinked chain and the molecular weight of the non-crosslinked homopolymer can be arbitrarily changed by appropriately adjusting the amount of the initiator.

The length (molecular weight) of the cross-chain portion can be estimated from the molecular weight of the homopolymer which has not been cross-linked, and the length is preferably 5000 to 15 ten thousand, more preferably 5000 to 10 ten thousand, and particularly preferably 5000 to 5 ten thousand in terms of weight average molecular weight. The molecular weight distribution (Mw/Mn) is preferably 3 or less, and particularly preferably 1.5 or less.

The total light transmittance of the sealing material resin mainly containing the cross copolymer obtained by the present production method and the sheet thereof at a thickness of 0.5mm is 80% or more, preferably 85% or more, and has high transparency. The sheet of the present encapsulating material has an a hardness of 50 or more and less than 70, preferably an a hardness of 50 or more and less than 65, and most preferably an a hardness of 50 or more and less than 63. Further, the storage elastic modulus (E') obtained by the viscoelasticity measurement is preferably 5X 10 at 100 ℃⁴Pa or more, particularly preferably 1X 10 at 100 DEG C⁵Pa or more, and has sufficient heat resistance when used as a solar cell sealing material. The MFR measured at 200 ℃ under a load of 10kg is not particularly limited, but is about 0.1g/10 min to 300g/10 min. The encapsulating material sheet of the present invention can exhibit high mechanical properties such as a breaking strength of 10MPa or more and an elongation at break of 300% or more as a soft resin.

In the encapsulating material resin and the sheet thereof of the present invention, "a light-resistant agent", "an antioxidant", "a silane coupling agent", "a plasticizer", "an adhesion improving agent" and "an antioxidant" may be added in addition to the cross copolymer.

< light resistance agent >

The light stabilizer for use in the encapsulating resin and the sheet thereof of the present invention is required to capture radicals generated by light, and if necessary, an ultraviolet absorber for converting light energy into harmless heat energy may be used in combination.

As the light stabilizer, a hindered amine light stabilizer is preferably used.

Examples of the ultraviolet absorber include benzotriazoles, triazines, benzophenones, benzoates, cyanoacrylates, oxanilides, and malonates.

The mass ratio of the ultraviolet absorbent to the light stabilizer is 0: 100-100: the total amount of the ultraviolet absorber and the hindered amine light stabilizer is defined as the light stabilizer mass in the range of 10, and the amount thereof is usually 0.001 to 3 mass% based on the total mass of the sealing material. These can be used alone in 1 kind, also can be combined with 2 or more kinds to use. The light-resistant agent can be purchased as Adekastab LA series from Adeka corporation, or as SUMISORB series from Sumika Chemtex Company, Limited (Sumika ケムテックス Co., Ltd.).

< antioxidant (anti-aging agent) >

In the encapsulating material resin and the sheet thereof of the present invention, various antioxidants such as phosphorus-based, lactone-based, vitamin E-based, sulfur-based, and phenol-based antioxidants can be suitably used as the antioxidant (antioxidant). The amount of the sealing material is usually in the range of 0.001 to 3 mass% based on the total mass of the sealing material. These can be used alone in 1 kind, also can be combined with 2 or more kinds to use.

< silane coupling agent >

In the encapsulating material resin and the sheet thereof of the present invention, a silane coupling agent is added as necessary for the purpose of improving adhesion and adhesion to a light-receiving surface side transparent protective member such as tempered glass, a back surface side protective member (backsheet), a solar cell itself, and wiring. The amount of the sealing material used is usually in the range of 0.001 to 3 mass% based on the total mass of the sealing material. The silane coupling agent is a silane compound having a functional group and a hydrolysis-condensation group in a molecule. Examples of the functional group include a vinyl group such as a vinyl group, a methacryloxy group, an acryloxy group, or a styryl group, an amino group, an epoxy group, a mercapto group, a thioether group, an isocyanate group, and a halogen. In view of high adhesion to glass, the functional group is preferably a vinyl group, an amino group, an epoxy group, a methacryloxy group, or an acryloxy group, and most preferably an amino group or a methacryloxy group. These functional groups may have a single or a plurality within the molecule. These coupling agents can be used in 1 or 2 or more.

Examples of the silane coupling agent having a vinyl group as a functional group include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of the silane coupling agent having a styryl group as a functional group include p-styryl trimethoxysilane. Examples of the silane coupling agent having an acryloxy group as a functional group include 3-acryloxypropyltrimethoxysilane. Examples of the silane coupling agent having a methacryloxy group as a functional group include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. Examples of the silane coupling agent having an epoxy group as a functional group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane. Examples of the silane coupling agent having an amino group as a functional group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldiethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, bis (3-trimethoxysilylpropyl) amine, N-N, N-N, Bis (3-triethoxysilylpropyl) amine, N- (N-butyl) -3-aminopropyltrimethoxysilane. The above examples have methoxy group and ethoxy group as the hydrolysis-condensation group, and triisopropoxy group and acetoxy group may be used.

< organic peroxide and crosslinking aid >

In the encapsulating material resin and the sheet thereof of the present invention, a known organic peroxide and an auxiliary agent may be added to the resin mainly for the purpose of grafting a silane coupling agent to the resin, within a range not impairing the thermoplasticity of the encapsulating material sheet of the present invention. The amount of the organic peroxide used is usually in the range of 0.001 to 0.5 mass% based on the total mass of the encapsulating material. These can be used alone in 1 kind, also can be combined with 2 or more kinds to use. Such peroxides are commercially available from Nichigan oil Co., Ltd., and Achima (アルケマ Co.).

The crosslinking assistant is not limited to the following, and examples thereof include triallyl isocyanurate, triallyl cyanurate, N' -phenylenebismaleimide, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, hexylene glycol di (meth) acrylate, nonanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and the like. These can be used alone in 1 kind, also can be combined with 2 or more kinds to use. When the addition agent is used, the content is not particularly limited, but is preferably in the range of 0.001 to 0.5 mass% based on the total mass.

< plasticizer >

The sealing resin and the sheet thereof of the present invention can further contain any known plasticizer conventionally used for vinyl chloride and other resins, if necessary, in an amount of 0.1 to 20 mass% based on the total mass of the sealing resin. The plasticizer preferably used is an oxygen-or nitrogen-containing plasticizer and is a plasticizer selected from an ester plasticizer, an epoxy plasticizer, an ether plasticizer, or an amide plasticizer.

These plasticizers are relatively compatible with the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer used in the cross-copolymer of the present invention, and are less likely to bleed out, and the plasticizing effect that can be evaluated by the degree of lowering of the glass transition temperature is also large, and can be preferably used.

Examples of ester plasticizers which can be preferably used in the present invention include phthalate esters, 1,2, 4-benzenetricarboxylate esters, adipate esters, sebacate esters, azelate esters, mono fatty acid esters such as citrate esters, acetyl citrate esters, glutamate esters, succinate esters, and acetate esters, phosphate esters, and polyesters thereof.

Examples of the epoxy plasticizer which can be preferably used in the present invention include epoxidized soybean oil and epoxidized linseed oil.

Examples of the ether plasticizer which can be preferably used in the present invention include polyethylene glycol, polypropylene glycol, copolymers thereof, and mixtures thereof.

Examples of amide plasticizers that can be preferably used in the present invention include sulfonamides. These plasticizers may be used alone or in combination.

In the present invention, ester plasticizers are particularly preferably used. These plasticizers have the advantages of excellent compatibility with the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer within the composition range, excellent plasticizing effect (high reduction of glass transition temperature), and less bleeding. Further, in the present invention, adipate plasticizers or acetylcitrate plasticizers are most preferably used.

The amount of the plasticizer to be blended is 1 part by mass or more and 30 parts by mass or less, preferably 1 part by mass or more and 20 parts by mass or less, per 100 parts by mass of the sealing material containing the cross copolymer of the present invention. If the amount is less than 1 part by mass, the above effects are insufficient, and if the amount is more than 30 parts by mass, bleeding, excessive softening, excessive stickiness due to the bleeding, excessive stickiness, or the like may be caused.

In addition, the fluidity of the encapsulating material can be improved by blending the plasticizer. In particular, when the MFR value of the cross-copolymer to be used is low, the MFR value suitable as an encapsulating material can be adjusted by adding the plasticizer in the above-mentioned range. As the additive used for improving the fluidity, in addition to the plasticizer, a hydrogenated petroleum resin is preferably used from the viewpoint of compatibility with the cross copolymer, transparency, and colorlessness.

The method of kneading the cross-copolymer with the above-mentioned additives can employ a known method generally used for adding additives to resins. For example, a twin-screw extruder, a Banbury mixer, a roll former, and the like can be used industrially. Thereafter, the sheet can be formed by a known molding method such as inflation molding, extrusion molding, T-die molding, calender molding, roll molding, or press molding. In order to impart good adhesion to glass, battery cells, metal wiring, a back sheet, and the like to the sealing material sheet, a well-known method can be used. For example, there is a method of adding at least a light-resistant agent, a silane coupling agent, an organic peroxide, and if necessary, a crosslinking assistant, an antioxidant, etc. of the above additives to the cross-linked copolymer, kneading the mixture under conditions in which the organic peroxide is effectively and sufficiently decomposed, grafting the silane coupling agent to the resin, and then forming a sheet as a thermoplastic sealing material. Further, there is a method of adding at least a light-resistant agent and, if necessary, an antioxidant, kneading the mixture, molding the kneaded mixture into a sheet, and applying a silane coupling agent by a known method. Examples of the coating method include a known method such as a gravure coating method, a roll coating method, a dip coating method, and a spray method. In this case, the coupling agent may be used by diluting it in an appropriate solvent, or may be used without diluting it. The sheet before or after coating may be subjected to corona treatment, plasma treatment, or electron beam irradiation as necessary to activate the surface or fix the surface with a coupling agent. Such a method is described in, for example, WO 2012033119.

< flake >)

When the sealing material resin containing a cross-linked copolymer of the present invention is used as a sheet for a solar cell sealing material, the thickness thereof is not particularly limited, and is usually 30 μm to 1mm, preferably 100 μm to 0.5 mm. In particular, a thin film sealing material of about 100 μm to 0.2mm is excellent in the performance of protecting a battery cell during the production (sealing) and the use in the environment. This is an example showing good sealing properties of the sealing material sheet of the present invention, but is not limited thereto. Such a thin film sealing material exhibits a performance of sealing without causing breakage of the battery cell during vacuum lamination, and further, even when a sealing material having a normal thickness (0.4 to 0.6mm) is used in industrial production, for example, the battery cell is less broken and the yield is likely to be improved. For producing the sheet made of the resin composition of the present invention, known molding methods such as inflation molding, extrusion molding (T-die molding), calender molding, roll molding, and the like can be used.

Examples of solar cells using the present encapsulant include various types of solar cells such as crystalline silicon-based, polycrystalline silicon-based, amorphous silicon-based, compound-based, and organic solar cells. In a form in which a solar cell such as a thin-film solar cell is closely adhered to a surface glass and transparency of an encapsulating material is not required, high moisture resistance (low water vapor transmission rate), high electrical insulation, and no release of a corrosive substance such as acetic acid are advantageous in terms of improvement in reliability of the solar cell.

Examples

The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to the examples. The analysis of the copolymer obtained in the examples was carried out by the following means.

The content of styrene units in the copolymer was determined by 1H-NMR, and alpha-500 manufactured by Nippon electronic Co., Ltd. or AC-250 manufactured by Bruker Co., Ltd. was used as a machine. Dissolving in deuterated 1,1,2, 2-tetrachloroethane, and measuring at 80-100 deg.C. The method is carried out by comparing the area intensity of a peak (6.5 to 7.5ppm) derived from a proton of a phenyl group with that of a peak (0.8 to 3ppm) derived from a proton of an alkyl group based on TMS.

Molecular weight the weight average molecular weight (Mw) and number average molecular weight (Mn) were calculated in terms of standard polystyrene by GPC (gel permeation chromatography). The measurement was performed under the following conditions.

Column: mixing TSK-GEL MultiporeHXL-M(manufactured by Tosoh corporation of imperial sciences, Inc.; manufactured by DONG CAO ソ -Inc.) 2 of the plants were used in series.

Column temperature: 40 deg.C

Solvent: THF (tetrahydrofuran)

Liquid delivery flow rate: 1.0 ml/min.

The DSC measurement was performed under a nitrogen stream using a DSC200 manufactured by seiko electronics corporation (セイコー electronic). That is, 10mg of the resin composition was used, and DSC measurement was performed at a temperature rise rate of 10 ℃/min from-50 ℃ to 240 ℃ to calculate the melting point, the crystal melting heat and the glass transition temperature. The 2 nd measurement was not performed after the 1 st measurement was rapidly cooled using liquid nitrogen.

< tensile test >

By a heat and pressure method (temperature 180 ℃, time 3 minutes, pressure 50 kg/cm)²) The resulting sheet was molded to a thickness of 1.0 mm. The sheet was cut into a shape of a test piece No. 2 No. 1/2 according to JIS K-6251, and measured at a tensile rate of 500 mm/min using an AGS-100D tensile tester manufactured by Shimadzu corporation.

Hardness

The hardness is a type A durometer hardness calculated according to the JIS K-7215 plastic durometer hardness test method. The hardness is an instantaneous value.

A sheet of the sealing material (thickness: 0.5mm, or thickness: 0.15mm) was heated and pressed (temperature: 180 ℃, time: 4 minutes, pressure: 50 kg/cm)²) And molding.

< Total light transmittance, haze >

The total light transmittance and haze were measured by using the above sheet having a thickness of 0.5mm by a haze meter NDH2000 manufactured by Nippon Denshoku industries Co., Ltd, according to the optical property test method of JIS K-7375 plastic.

< viscoelastic spectrum >

A measurement sample (3 mm. times.40 mm) was cut from the sheet having a thickness of 0.5mm, and the measurement was carried out at a frequency of 1Hz and a temperature range of-50 ℃ to +250 ℃ using a dynamic viscoelasticity measuring apparatus (Rheometrics Corporation, レオメトリックス, RSA-III).

The other major assay parameters involved in the assay are as follows.

Temperature rise rate: 4 ℃ per minute

Length of sample measurement: 10mm

Initial Static Force (Initial Static Force): 5.0g

Auto Tension Sensitivity (Auto Tension Sensitivity): 1.0g

Maximum Auto stretch Rate (Max Auto Tension Rate): 0.033mm/s

Maximum Applied Strain (Max Applied Strain): 1.5 percent

Minimum Allowed Force (Min Allowed Force): 1.0g

< Water vapor Transmission Rate >

The water vapor permeability was measured by the JISZ0208 cup method using the above 0.5mm thick sheet at 40 ℃ and 90% humidity for 100 hours.

< volume resistivity >

The measurement was carried out at room temperature in accordance with JIS K6911 using the above-mentioned sheet having a thickness of 0.5 mm.

< breakdown Voltage >

The measurement was carried out at room temperature according to JISC2110 using the above-mentioned 0.5mm thick sheet.

< Divinylbenzene >

The m-divinylbenzene used in the following production examples was produced by Aldrich (アルドリッチ Co.) (divinylbenzene purity: 80%, m-isomer/p-isomer mass ratio in a mixture of m-and p-isomers: 70: 30).

< catalyst (transition metal Compound) >)

In the following production examples, rac (racemate) -dimethylmethylenebis (4, 5-benzo-1-indenyl) zirconium dichloride (formula 7) was used as a catalyst (transition metal compound).

Production example 1

< production of Cross copolymer >

Using rac-dimethylmethylenebis (4, 5-benzo-1-indenyl) zirconium dichloride as catalyst, the procedure was carried out as described below.

Polymerization was carried out in a polymerization tank (autoclave) for coordination polymerization having a capacity of 50L and equipped with a stirrer and a jacket for heating and cooling. 21.3kg of cyclohexane, 3.2kg of styrene, and divinylbenzene (m-and p-mixtures, purity: 81 mass%, divinylbenzene content: 61 mmol) manufactured by Nissian iron chemical Co., Ltd were added thereto, and the mixture was stirred (220rpm) at an internal temperature of 60 ℃. The dry nitrogen gas was bubbled through the liquid at a flow rate of 10L/min for about 15 minutes to purge the water from the system and the polymerization liquid. Then, 50 mmol of triisobutylaluminum and 60 mmol, based on Al, of methylaluminoxane (MMAO-3A/hexane solution manufactured by Tosoh Aksu corporation (manufactured by imperial ソーアクゾ)) (MAO shown in the table) were added thereto, and the inside of the system was immediately washed with ethylene. After thorough washing, the internal temperature was raised to 85 ℃ and ethylene was introduced, stabilized at a pressure of 0.4MPa (3 kg/cm)²G) Then, from a catalyst tank provided in the autoclave, 80. mu.mol of rac-dimethylmethylenebis (4, 5-benzo-1-indenyl) zirconium dichloride and about 50ml of a toluene solution in which 1 mmol of triisobutylaluminum was dissolved were addedInto an autoclave. Further, ethylene was supplied through a flow rate control valve, and polymerization was carried out while maintaining an internal temperature of 90 ℃ and a pressure of 0.4 MPa. The progress of polymerization was monitored from the flow rate and the cumulative flow rate of ethylene. After the predetermined ethylene flow rate was reached, the supply of ethylene was stopped, the pressure was released, and the internal temperature was cooled to 70 ℃ (or more, the coordination polymerization step). Subsequently, the polymerization solution was transferred to a polymerization tank for anion polymerization having a capacity of 50L and equipped with a stirrer and a jacket for heating and cooling. At the same time, several tens of ml of the polymer solution for analysis was collected. 220 mmol of n-butyllithium was introduced into a polymerization vessel for anion polymerization together with nitrogen gas from a catalyst vessel (a crossing step). The anionic polymerization started immediately and the internal temperature rose briefly from 70 ℃ to 80 ℃. The temperature was maintained at 70 ℃ for 30 minutes while maintaining this state, and the polymerization was continued with continued stirring. About one hundred milliliters of methanol was added to the polymerization tank to stop the anionic polymerization. After the polymerization was stopped, the obtained polymer solution was put into a large amount of vigorously stirred methanol solution in small amounts at a time to recover the polymer. The polymer was air-dried at room temperature for 1 day and night, and then dried at 60 ℃ in vacuum until no change in mass was observed.

Production examples 2 to 3

Polymerization was carried out under the conditions shown in table 1 in the same manner as in production example 1.

[ Table 1]

1) Cyclohexane 2) DVB (Divinylbenzene)

The analytical values of the obtained ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer are shown in Table 2, and the analytical values of the obtained cross copolymer after the anionic polymerization step are shown in Table 3.

[ Table 2]

At the same time, no melting point peak having a crystal melting heat of 10J/g or more was observed.

[ Table 3]

Examples 1,2 and 3 and comparative examples 1,2 and 3

The cross-copolymers obtained in production examples 1,2 and 3 satisfy the conditions of the present invention, and the cross-copolymer obtained in production example 3 does not satisfy the conditions of the present invention. In addition to the cross-copolymers of the production examples, ENGAGE8100 (density 0.870) and PL1880 (density 0.902) which were commercially available LLDPE (ethylene-octene copolymer) were prepared. Using the LLDPE prepared in production examples 1 to 3 and commercially available, an encapsulant resin was obtained according to the formulation shown in Table 4. KBM-903 (silane coupling agent available from shin-Etsu chemical Co., Ltd.), PERHEXANA 25B (organic peroxide available from Nichiku K.K.), LA57 (hindered amine light stabilizer available from Aidick Co., Ltd.), Uvinul3035 (ultraviolet absorber available from BASF Co., Ltd.), and SUMISORB130 (ultraviolet absorber) were used for blending. The cross-linked copolymer and the various additives were kneaded together in an amount of about 200g per kneading using a Banbury mixer (Laboplastomill B-250) according to the formulation (parts by mass) shown in Table 4 at 200 ℃ for 7 minutes at 100rpm, to produce a potting resin. Examples 1 and 2 are sealing material resins obtained by using the cross-copolymers obtained in production examples 1 and 2, respectively, and example 3 is a sealing material resin obtained by using the cross-copolymer obtained in production example 2 but changing the silane coupling agent. Comparative example 1 is an encapsulant resin obtained using the cross-copolymer obtained in production example 3. Comparative examples 2 and 3 are encapsulant resins obtained using ENGAGE8100 and PL1880, respectively. Various physical properties were measured using the obtained sealing resin and a sheet having a thickness of 0.5mm obtained by the above-described heating and pressing method, and are shown in table 4. However, only A hardness was measured by separately producing a sheet having a thickness of 1.0mm by the same pressing method in accordance with JIS K-7215 and stacking 5 sheets.

Further, a sheet of the sealing material (hereinafter referred to as 0.15mm) having a thickness of 0.5mm and a thickness of 0.15 to 0.20mm was produced by the same heating and pressing method. A solar cell module was obtained by stacking a tempered glass for a solar cell (thickness 3.2mm), an obtained encapsulating material sheet, a polycrystalline silicon unit (thickness 200 μm with TAB wire), an encapsulating material sheet, and a TPT-type back sheet in this order from below using a vacuum laminator (LM-50X50-S) for a solar cell module manufactured by NPC corporation, and encapsulating the stack under the conditions shown in table 5, that is, at a temperature of 150 ℃, a vacuum was applied for 5 minutes, and a pressing time in vacuum with a separator interposed therebetween was 30 minutes or 3 minutes. In each of the examples and comparative examples, 4 modules were prepared under the same conditions. The presence or absence of cell breakage or disconnection in the module was checked by visual inspection and EL measurement, the presence or absence of voids (bubbles, peeling, etc.) and adhesion failure were checked by visual inspection, and evaluation was evaluated as ≈ when no abnormality was observed in 4, as Δ when abnormality was observed in 1 of 4, and as × when abnormality was observed in 2 or more of 4. The number of battery cells in which abnormality was observed is shown in table 5.

[ Table 4]

[ Table 5]

Further, using the same apparatus, a tempered glass for solar cell (thickness: 3.2mm), the obtained sealing material sheet, and a TPT type back sheet were stacked in this order from the bottom, and pressure-bonded under conditions of evacuation at 150 ℃ for 3 minutes and pressurization for 30 minutes, to obtain a sample for evaluation of adhesion. A long strip of 25mm in width was cut from the resin portion of the obtained sample, and the peel strength between the glass and the sealing material was measured. The measurement was carried out at a speed of 100 mm/min under 180-degree peel conditions using an AGS-100D tensile tester manufactured by Shimadzu corporation. In examples 1,2 and 3 and comparative examples 1 and 2, the peel strength was 40N/25mm or more, and the higher peel strength could not be measured.

It is understood that the sealing material resins of examples 1,2 and 3 using the cross-copolymers obtained in production examples 1 and 2 exhibit high softness, good mechanical properties, transparency, heat resistance, electrical insulation and moisture resistance. When the sealing materials of examples 1,2, and 3 were used, solar cell modules were produced which were free from cell breakage and disconnection, had no voids, and adhesion failure, and were capable of sealing under various conditions.

Using the above vacuum laminator, from below, according to the solar cell tempered glass (thickness 3.2mm), the encapsulant resin obtained in examples 1,2 and 3, and the encapsulant sheets (thickness 0.5mm, 0.15mm) obtained by the above heat and pressure method, polysilicon CELLS (Q-CELLS corporation, Q セル, manufactured by 156mm long and wide, thickness 200 μm, with TAB wire), the same encapsulant sheets (thickness 0.5mm, 0.15mm), and TPT type back sheets were sequentially stacked, and a module (4) was obtained under conditions of evacuation at 150 ℃ for 3 minutes and pressure for 3 minutes, using the module (4), 2 of them were used for DH-1000 (according to IEC 6121510.3 damp heat test, treated at 85 ℃ for 1000 hours at humidity 85%), and the other 2 were used for TC-50/HF-10 (according to IEC6121510.12 and 10.11, cycling 50 times at-40-85 deg.C/10 times at 85 deg.C with the same cycle and humidity of 85%). In any of the modules after the test, no cell breakage, disconnection, voids due to peeling, adhesion failure, and the like were observed.

Examples 4 to 9

Using the vacuum laminator, solar cell modules (single cell units) were obtained by stacking, from the bottom, the tempered glass for solar CELLS (thickness 3.2mm), the encapsulant resin obtained in examples 1,2 and 3, and the encapsulant sheets (thickness 0.5mm and 0.2mm) obtained by the heat-pressing method, the polysilicon CELLS (length 156mm, width 200 μm, TAB line, manufactured by Q-CELLS corporation), the same encapsulant sheets (thickness 0.5mm and 0.2mm), and the TPT-type back sheet in this order, and encapsulating the same under the conditions shown in table 6. Initial IV characteristics and maximum power generation (Pmax) were measured by a solar simulator (SPI-sussimilator 1116N) manufactured by riqing precision mechanical co. Subsequently, the above DH-1000 test was repeated 5 times. The modules were removed every 1000 hours and measured using the solar simulator described above.

Comparative example 4

A comparative module was prepared in the same manner as in example 4, using a commercially available EVA sealing material (thickness 0.5mm) as the sealing material. In order to sufficiently crosslink EVA, encapsulation was performed at 150 ℃ for 30 minutes. After measurement using a solar simulator, the DH-1000 test was repeated in the same manner as described above.

All the modules fall within the range of 3.8-4.0W for the initial Pmax after the modules are manufactured. It is considered that the variation in Pmax in this range is caused by the variation in power generation performance among the crystalline silicon cells. The proportion of Pmax after the DH test to the initial Pmax for each module was expressed in%.

The results of the examples and comparative examples are shown in table 6 and fig. 2. The solar cell module using the encapsulant made of the cross-linked copolymer of the present invention showed excellent durability without substantial change in power generation performance even after 5 times of DH-1000 test (i.e., after 5000 hours). On the other hand, in the case of the module using the EVA sealing material, a significant decrease in power generation performance was observed after 2 DH-1000 tests (i.e., after 2000 hours). At the end of 3 times (3000h), the ratio of the drop-out performance criterion, i.e., the initial Pmax, was 95% or more, and therefore the test was terminated thereafter.

Industrial applicability

The encapsulating material resin and sheet thereof of the present invention are excellent in mechanical properties, transparency, heat resistance, electrical insulation, moisture resistance, and softness and encapsulating property, and are applicable as a new thermoplastic encapsulating material suitable as a thin-layer encapsulating material, for example, regardless of the type of crystalline or thin-film solar cell.

Description of the symbols

Transparent protection member for light receiving surface side A

B Back side protection component (Back plate)

C1 light-receiving surface side packaging material

C2 Back side sealing Material

Cell for solar cell

[ Table 6]

Claims

1. An encapsulating material resin comprising a cross-copolymer obtained by a production method comprising:

a coordination polymerization step of copolymerizing a vinyl monomer, an aromatic vinyl compound monomer and an aromatic polyene using a single-site coordination polymerization catalyst to synthesize a vinyl-aromatic vinyl compound-aromatic polyene copolymer macromonomer having an aromatic vinyl compound unit content of 17 to 30 mol%, an aromatic polyene unit content of 0.01 to 0.2 mol%, and a vinyl unit content as the remainder,

and a polymerization step comprising an anionic polymerization step of polymerizing the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer using an anionic polymerization initiator in the coexistence of the aromatic vinyl compound monomer;

wherein,

(1) the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer obtained in the coordination polymerization step has a weight average molecular weight of 3 to 15 ten thousand and a molecular weight distribution Mw/Mn of 1.8 to 4;

(2) the crystallization melting heat delta H observed at 0-150 ℃ of the ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer is below 30J/g; and

2. An encapsulating material resin according to claim 1, wherein the a hardness is 50 or more and less than 70.

3. The encapsulant resin as claimed in claim 1, wherein the storage elastic modulus E' at 100 ℃ is 5 x 10⁴Pa or above.

4. An encapsulating material resin according to claim 1, further comprising one or more additives selected from the group consisting of a light-resistant agent in an amount within a range of 0.001 to 3% by mass, a silane coupling agent in an amount within a range of 0.001 to 3% by mass, an organic peroxide in an amount within a range of 0.001 to 0.5% by mass, and a crosslinking assistant in an amount within a range of 0.001 to 0.5% by mass, based on the total mass of the encapsulating material.

5. An encapsulating material resin according to claim 1, further comprising an additive containing a light-resistant agent in an amount within a range of 0.001 to 3% by mass, a silane coupling agent in an amount within a range of 0.001 to 3% by mass, and an organic peroxide in an amount within a range of 0.001 to 3% by mass, based on the total mass of the encapsulating material.

6. An encapsulating material sheet composed of the encapsulating material resin according to any one of claims 1 to 5.

7. A solar cell using the sheet of encapsulant material of claim 6.