JP6613649B2 - Adhesive composition, laminated sheet, back surface protection sheet for solar cell - Google Patents

Description

The present invention relates to an adhesive composition, and more specifically, an adhesive composition that exhibits high adhesive strength between various sheet-like members and can maintain high adhesive strength even when exposed to a high temperature and high humidity environment, and a laminated sheet , And a back surface protection sheet for solar cells.

  In recent years, with the increase in functionality of laminated sheets, for example, barrier materials, outer wall materials, roofing materials, solar cell panel materials (back surface protection sheets for solar cells, solar cell surface protection sheets), window materials, outdoor flooring materials, lighting protection, etc. Multilayer laminated bodies used for materials, automobile members, signboards, stickers, packaging materials, laminated steel plates, etc. have been put into practical use. The multilayer laminate can be obtained by laminating (laminating) a metal material or a plastic material. Examples of the metal-based material include metal foils such as aluminum, copper, and steel plates, metal plates, and metal vapor deposition films. Plastic materials include plastic films such as polypropylene, polyethylene, polyvinyl chloride, polyester, fluororesin and acrylic resin, plastic films with inorganic oxide layers formed on the surface, such as plastic sheets, plastic plates, and silica-deposited films. Can be mentioned. Conventionally, epoxy adhesives, polyurethane adhesives, and acrylic adhesives are known as adhesives used for joining metal materials and plastic materials.

Patent Document 1 describes a solar cell back surface sealing sheet using an acrylic resin and an adhesive based on an isocyanate curing agent.

Patent Document 1 shows a high adhesive strength between various sheet-like members, particularly between layers including a surface treatment layer of a plastic film, by blending acrylic polyol and polyisocyanate in a specific range. The adhesive composition suitable for manufacture of the back surface protection sheet for solar cells which can maintain high adhesive force even if it exposes under is described.

However, the isocyanate curing agent used here reacts with moisture to form unstable carbamic acid when the removal of moisture in the atmosphere and residual moisture contained in the system is insufficient. Decomposes to carbon. Amine quickly reacts with isocyanate to form urea, while the generated carbon dioxide creates bubbles in the adhesive sheet, which can weaken the adhesive strength or impair the appearance. Had to do.

Patent 5003849

It is not affected by moisture during the production of laminated sheets and exhibits high adhesion between various sheet-like members, especially between layers including the plastic film surface treatment layer, and maintains high adhesion even when exposed to high-temperature and high-humidity environments. It is providing the adhesive composition which can be performed, a lamination sheet, and the back surface protection sheet for solar cells.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the adhesive composition shown below, and have completed the present invention.

That is, the adhesive composition according to the present invention is an adhesive composition comprising a curable compound (X) having a diene structure and a curable compound (Y) having a dienophile structure,
The diene structure is a furan structure, and
The present invention relates to an adhesive composition characterized in that the dienophile structure is a maleimide structure.
The present invention also relates to the adhesive composition, wherein the curable compound (X) is poly (meth) acrylate (X-1) having a furan structure in the side chain.
The present invention also relates to the adhesive composition, wherein the poly (meth) acrylate (X-1) having a furan structure in the side chain contains furfuryl methacrylate in the copolymer composition.
The present invention also relates to the adhesive composition, further comprising a silane coupling agent.
Moreover, this invention relates to the laminated sheet containing the adhesive bond layer formed from the said adhesive composition.
Moreover, this invention relates to the back surface protection sheet for solar cells containing the adhesive bond layer formed from the said adhesive composition.

According to the present invention, it is not affected by moisture during the production of a laminated sheet, exhibits high adhesion between various sheet-like members, particularly between layers including a surface treatment layer of a plastic film, and is exposed to a high temperature and high humidity environment. In addition, an excellent effect that a high adhesive force can be maintained is obtained.

The present invention will be described in detail below. In the present invention, (meth) acrylate means acrylate and / or methacrylate.

<Adhesive composition>
The adhesive composition of the present invention is an adhesive composition comprising a curable compound (X) having a diene structure and a curable compound (Y) having a dienophile structure, wherein the diene structure is a furan structure. In addition, the dienophile structure is a maleimide structure. This adhesive composition can form an adhesive layer by causing a Diels-Alder reaction.

[Diels Alder reaction]
First, the Diels-Alder reaction by a diene structure and a dienophile structure will be described. The diene structure and dienophile structure of the present invention represent a diene structure and dienophile structure capable of Diels-Alder reaction. The Diels-Alder reaction is a cycloaddition reaction of a diene and a dienophile, creating three new bonds (two σ bonds and one π bond), and three bonds (two diene π bonds and one alkene). This is a reaction in which the cleavage of the π bond occurs simultaneously. The reaction proceeds only with heat, but a Lewis acid may be added as a catalyst.

The diene structure is preferably unsubstituted or a conjugated diene structure having a generally electron-donating substituent, and specific examples include a 1,3-butadiene structure, a furan structure, and an anthracene structure.
The dienophile structure is generally preferably a double or triple bond having an electron-withdrawing group as a substituent, and specific examples thereof include a maleic anhydride structure, a maleimide structure, and an acrylate structure.

The Diels-Alder reaction of furan structure and maleimide structure is known to be biased toward bond formation (addition) reaction at room temperature to 90 ° C, and to be dissociated at 90 ° C or higher. The structure addition reaction has the optimum curing temperature as an adhesive.

The Lewis acid used as a catalyst includes aluminum chloride, tin tetrachloride, iron trichloride, titanium trichloride, titanium tetrachloride, boron trifluoride, alkylaluminum compounds (such as trimethylaluminum), polyaluminoxane compounds (polymethylaluminoxane). , Sulfonimide-modified polyaluminoxane compounds, sulfonic acid-modified polyaluminoxane compounds, reaction products of polymethylaluminoxane and bistrifluoromethanesulfonimide, etc.), scandium compounds (scandium (III) perfluorooctane sulfonate, etc.) The addition reaction temperature can be lowered.
In addition, as co-catalysts, strong alkaline salts of weak acids such as aliphatic or aromatic esters, chloroacetic esters, ethers, ketones, carbonates and nitro compounds, amines, organic carboxylic acids and phosphoric acids (sodium acetate) , Disodium hydrogen phosphate, etc.), oxides of alkali metals and alkaline earth metals, hydroxides, carbonates, bicarbonates (calcium oxide, magnesium oxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, etc.), etc. Can be used.

[Curable compound (X) having a diene structure]
The curable compound (X) having a diene structure will be described. The curable compound (X) is not particularly limited as long as it has a furan structure as a diene structure, and can be used as a main agent or a curing agent. Preferred specific examples include poly (meth) acrylates, polyurethanes, polyesters, polyamides, polyimides, polycarbonates, polyolefins, polystyrenes, polysiloxanes, polyethers, copolymers containing maleic anhydride, and epoxy resins having a furan structure. These can be used alone or as a mixture. Among these, the poly (meth) acrylate (X-1) having a furan structure in the side chain can easily introduce the furan structure into the curable compound (X), and can easily control the introduction amount of the furan structure. In addition, since the molecular weight and copolymer composition of the poly (meth) acrylate (X-1) can be easily controlled, it is preferable because various physical properties necessary as an adhesive such as moisture and heat resistance and suppression of foaming can be achieved in addition to adhesive strength. Furthermore, it is particularly preferable that furfuryl (meth) acrylate is included in the copolymer composition in terms of adhesive strength with the substrate.

[Poly (meth) acrylate having furan structure (X-1)]
As a method for introducing a furan structure into poly (meth) acrylate, poly (meth) acrylate having no furan structure may be reacted with a “reactive compound having a furan structure”, or “a monomer having a furan structure”. May be polymerized. In the present invention, the latter is more preferable because the reaction process of synthesis can be reduced. Further, it may be a homopolymer or a copolymer with other monomers.

Examples of the “reactive compound having a furan structure” include furfuryl alcohol, furfurylamine, furfuryl mercaptan, and furfural. By reacting these with a poly (meth) acrylate having a carboxyl group, an epoxy group, an isocyanate group, an acid anhydride group, or the like, a furan structure can be introduced into the poly (meth) acrylate.

Examples of the “monomer having a furan structure” include monomers represented by the following general formulas [1] to [5] derived from furfuryl alcohol, furfurylamine, furfuryl mercaptan, furfural and the like. Among these, as described above, a copolymer containing furfuryl (meth) acrylate (general formula [1]) in the copolymer composition is particularly preferable in terms of adhesive strength with the substrate.

General formula [1]



(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an oxygen atom or NH.)

General formula [2]


(In the formula, R ₃ represents a hydrogen atom or a methyl group, and R ₄ represents an oxygen atom, NH, or a sulfur atom.)

General formula [3]



(In the formula, R ₅ represents a hydrogen atom or a methyl group, and R ₆ represents an oxygen atom, NH, or a sulfur atom.)

General formula [4]



(In the formula, R ₇ represents a hydrogen atom or a methyl group, and R ₈ represents an oxygen atom, NH, or a sulfur atom.)

General formula [5]


(In the formula, R ₉ represents a hydrogen atom or a methyl group, and R ₁₀ represents an oxygen atom, NH, or a sulfur atom.)

Examples of those represented by the general formula [2] include adducts of (meth) acryloyloxyethyl isocyanate and furfuryl alcohol.
Examples of those represented by the general formula [5] include adducts of 2-hydroxyethyl (meth) acrylate, isophorone diisocyanate, and furfuryl alcohol.

In the poly (meth) acrylate (X-1) having a furan structure, examples of monomers that can be copolymerized include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 1,4- Hydroxyl group-containing monomers such as butanediol mono (meth) acrylate, (poly) ethylene glycol mono (meth) acrylate, 2,3-dihydroxypropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Alkyl (meth) acrylate monomers such as tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate and stearyl (meth) acrylate Long chain (meth) acrylic monomers represented, acrylonitrile, (meth) acrylic acid, maleic acid, carboxyl group-containing monomer or its anhydride such as maleic anhydride, or a vinyl monomer such as styrene. In addition, these monomers may use one type of compound, or may use it in combination of 2 or more types of compounds. The same applies to the case of using other monomers.

Alkyl (meth) acrylate monomers are carbon atoms that are bonded to (meth) acrylic acid moieties via ester bonds (hereinafter referred to as “side chain moieties” in alkyl groups and alkenyl groups) from the viewpoint of improving adhesive strength. The number of is preferably 1 to 17, more preferably 1 to 9, and still more preferably 1 to 4. As such examples, for example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate Long chain (meth) acrylic monomers represented by alkyl (meth) acrylate monomers such as tridecyl (meth) acrylate and stearyl (meth) acrylate.

In addition, the mono (meth) acrylate monomer containing a hydroxyl group or a carboxyl group described above not only contributes to an improvement in adhesive strength, but is further combined with a polyisocyanate, an epoxy resin, or the like, and further crosslinked with a hydroxyl group or a carboxyl group. The adhesion and strength of the coating film can be improved.

The introduction amount of the mono (meth) acrylate monomer containing a hydroxyl group or a carboxyl group is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the poly (meth) acrylate having a furan structure. More preferred are parts by weight. If the amount is less than 0.1 part by weight, the effect of introducing a functional group cannot be obtained.

As the poly (meth) acrylate (X-1) having a furan structure, a copolymer of a monomer having a furan structure and an alkyl (meth) acrylate monomer is preferably used. The amount of furan structure introduced is determined by the content of the monomer having a furan structure. In the present invention, the content of furan structure (furfuryl group) in the copolymer is preferably 0.01 to 2 mmol / g, 0 0.05-1 mmol / g is more preferable, and 0.05-0.5 mmol / g is still more preferable. If it is less than 0.01 mmol / g, the crosslinking density with the maleimide structure tends to decrease, and the heat and moisture resistance may decrease. On the other hand, if it exceeds 2 mmol / g, the adhesive strength before aging can be expressed, but the crosslinking density tends to increase after aging, and sufficient adhesive strength cannot be expressed. May decrease.

Here, aging means coating and drying the adhesive composition on the joint surface of one sheet-like member, then overlaying the other sheet-like member on the adhesive layer, and in an environment of 20 ° C to 70 ° C. In this process, the laminate sheet is obtained by storing for about 1 day to 1 week to advance the curing of the adhesive layer. In order to accelerate curing, a Lewis acid catalyst may be added, and aging can be performed at a lower temperature and in a shorter time.

Moreover, in this invention, the glass transition point (Tg) of poly (meth) acrylate (X-1) which has a furan structure exceeds -40 degreeC from a viewpoint of the adhesive force after aging, and the adhesive force after heat-and-moisture resistance. , 40 ° C. or less is preferable, exceeding −25 ° C. and more preferably 20 ° C. or less. If the Tg is too low, the adhesive layer before aging is still insufficiently cured, so the adhesive layer formed from the adhesive composition is soft, and a certain degree of adhesive strength can be expressed between the sheet-like members due to the softness. . However, even if the adhesive layer is sufficiently cured after aging, since the Tg is low, a lack of cohesive force of the adhesive layer becomes obvious, and it tends to be difficult to ensure a large adhesive force. Furthermore, when the laminate is placed under high temperature and high humidity for a long time, the adhesive force tends to gradually decrease due to insufficient cohesive force of the adhesive layer.
On the other hand, when Tg is too high, the wettability to the substrate tends to be insufficient. Although the adhesive strength after aging becomes somewhat larger than before aging, the cured adhesive layer after crosslinking becomes too hard, and thus the adhesive strength after the aging process tends to be low.

The weight average molecular weight of the curable compound (X) having a diene structure is preferably 20,000 to 300,000, and more preferably 50,000 to 150,000. When the weight average molecular weight is less than 20,000, the cohesive force of the adhesive layer before the aging process tends to be insufficient, and the adhesive force before the aging process may be reduced. In the case of industrial production, the laminated body wound up in a roll is usually aged with the winding core in the vertical direction. If the adhesive strength before the aging process is small, the winding tends to collapse during aging, which is not suitable for industrial production. Moreover, if it is less than 20,000, the cohesive force after an aging process tends to be insufficient, and accordingly, heat and humidity resistance is lowered, and delamination may occur. When the weight average molecular weight exceeds 300,000, the viscosity of the adhesive increases, and there is a tendency for the coatability to occur, or the wettability to the sheet-like member tends to decrease. As a result, the adhesive strength before the aging process May become smaller. Although the initial adhesive strength is increased by aging as compared with that before aging, it is gradually decreased by a subsequent heat and humidity resistance test and may be lower than the lower limit of use after 3000 hours.

  In addition, the weight average molecular weight in this invention is the value calculated | required by gel permeation chromatography (GPC) and polystyrene conversion. More specifically, the weight average molecular weight in this invention has shown the value calculated | required with the measuring method as described in the Example mentioned later. Moreover, about the glass transition temperature, the value calculated | required by the method as described in the Example mentioned later similarly is shown.

[Curable compound (Y) having a dienophile structure]
The curable compound (Y) having a dienophile structure will be described. The curable compound (Y) is not particularly limited as long as it has a maleimide structure as a dienophile structure, and can be used as a main agent or a curing agent. As a preferable specific example,
o-phenylene bismaleimide, m-phenylene bismaleimide, p-phenylene bismaleimide, 4-methyl-1,3-phenylene bismaleimide, N, N ′-(toluene-2,6-diyl) bismaleimide), 4, 4'-diphenylmethane bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4,4'-diphenyl ether bismaleimide, 4,4'- Diphenylsulfone bismaleimide, 1,3-bis (3-maleimidophenoxy) benzene, 1,3-bis (4-maleimidophenoxy) benzene, polyphenylmethanemaleimide (CAS NO: 6778474-1, consisting of formaldehyde and aniline) Polymer and maleic anhydride Acid reaction product), N, N′-ethylene bismaleimide, N, N′-trimethylene bismaleimide, N, N′-propylene bismaleimide, N, N′-tetramethylene bismaleimide, N, N′— Pentamethylene bismaleimide, N, N ′-(1,3-pentanediyl) bis (maleimide) N, N′-hexamethylene bismaleimide, N, N ′-(1,7-heptanediyl) bismaleimide, N, N '-(1,8-octanediyl) bismaleimide, N, N'-(1,9-notanediyl) bismaleimide, N, N '-(1,10-decanediyl) bismaleimide, N, N'-(1 , 11-undecandiyl) bismaleimide, N, N ′-(1,12-dodecandiyl) bismaleimide, N, N ′-[(1,4-phenylene) bismethylene] bismaleimide, N N ′-[(1,2-phenylene) bismethylene] bismaleimide, N, N ′-[(1,3-phenylene) bismethylene] bismaleimide, 1,6′-bismaleimide- (2,2,4-trimethyl) ) Hexane, N, N '-[(methylimino) bis (4,1-phenylene)] bismaleimide,
N, N '-(2-hydroxypropane-1,3-diylbisiminobiscarbonylbisethylene) bismaleimide, N, N'-(dithiobisethylene) bismaleimide, N, N '-[hexamethylenebis (imino Carbonylmethylene)] bismaleimide, N, N′-carbonylbis (1,4-phenylene) bismaleimide, N, N ′, N ″-[nitrilotris (ethylene)] trismaleimide, N, N ′, N ′ '-[Nitrilotris (4,1-phenylene)] trismaleimide, N, N'-[p-phenylenebis (oxy-p-phenylene)] bismaleimide, N, N '-[methylenebis (oxy) bis (2 -Methyl-1,4-phenylene)] bismaleimide, N, N '-[methylenebis (oxy-p-phenylene)] bis (maleimide) , N '-[dimethylsilylenebis [(4,1-phenylene) (1,3,4, -oxadiazole-5,2-diyl)] (4,1-phenylene)]] bismaleimide, N, N' -[(1,3-phenylene) bisoxybis (3,1-phenylene)] bismaleimide, 1,1 '-[3'-oxospiro [9H-xanthene-9,1'(3'H) -isobenzofuran]- 3,6-diyl] bis (1H-pyrrole-2,5-dione), N, N ′-(3,3′-dichlorobiphenyl-4,4′-diyl) bismaleimide, N, N ′-(3 3′-dimethylbiphenyl-4,4′-diyl) bismaleimide, N, N ′-(3,3′-dimethoxybiphenyl-4,4′-diyl) bismaleimide, N, N ′-[methylenebis (2- Ethyl-4,1-phenylene)] bismaleimide, , N ′-[methylenebis (2,6-diethyl-4,1-phenylene)] bismaleimide, N, N ′-[methylenebis (2-bromo-6-ethyl-4,1-phenylene)] bismaleimide, N , N ′-[methylenebis (2-methyl-4,1-phenylene)] bismaleimide, N, N ′-[ethylenebis (oxyethylene)] bismaleimide, N, N ′-[sulfonylbis (4,1- Phenylene) bis (oxy) bis (4,1-phenylene)] bismaleimide, N, N ′-[naphthalene-2,7-diylbis (oxy) bis (4,1-phenylene)] bismaleimide, N, N ′ -[P-phenylenebis (oxy-p-phenylene)] bismaleimide, N, N ′-[(1,3-phenylene) bisoxybis (3,1-phenylene)] bismaleimide, N, N ′ (3,6,9-trioxaundecane-1,11-diyl) bismaleimide, N, N '-[isopropylidenebis [p-phenyleneoxycarbonyl (m-phenylene)]] bismaleimide, N, N'- [Isopropylidenebis [p-phenyleneoxycarbonyl (p-phenylene)]] bismaleimide, N, N ′-[isopropylidenebis [(2,6-dichlorobenzene-4,1-diyl) oxycarbonyl (p-phenylene) )]] Bismaleimide, N, N ′-[(phenylimino) bis (4,1-phenylene)] bismaleimide,
N, N ′-[azobis (4,1-phenylene)] bismaleimide, N, N ′-[1,3,4-oxadiazole-2,5-diylbis (4,1-phenylene)] bismaleimide, 2,6-bis [4- (maleimido-N-yl) phenoxy] benzonitrile, N, N ′-[1,3,4-oxadiazole-2,5-diylbis (3,1-phenylene)] Bismaleimide, N, N ′-[bis [9-oxo-9H-9-phospha (V) -10-oxaphenanthren-9-yl] methylenebis (p-phenylene)] bismaleimide, N, N ′-[hexa Fluoroisopropylidenebis [p-phenyleneoxycarbonyl (m-phenylene)]] bismaleimide, N, N ′-[carbonylbis [(4,1-phenylene) thio (4,1-phenylene)]] bi Maleimide, N, N′-carbonylbis (p-phenyleneoxy p-phenylene) bismaleimide, N, N ′-[5-tert-butyl-1,3-phenylenebis [(1,3,4-oxadiazole -5,2-diyl) (4,1-phenylene)]] bismaleimide, N, N '-[cyclohexylidenebis (4,1-phenylene)] bismaleimide,
N, N ′-[methylenebis (oxy) bis (2-methyl-1,4-phenylene)] bismaleimide,
N, N ′-[5- [2- [5- (dimethylamino) -1-naphthylsulfonylamino] ethylcarbamoyl] -1,3-phenylene] bismaleimide, N, N ′-(oxybisethylene) bismaleimide N, N ′-[dithiobis (m-phenylene)] bismaleimide, N, N ′-(3,6,9-trioxaundecane-1,11-diyl) bismaleimide, N, N ′-(ethylenebis) -P-phenylene) bismaleimide,
BMI-689, BMI-1500, BMI-1700, BMI-3000, BMI-5000, BMI-9000, manufactured by Designer Molecules
Examples thereof include polyfunctional maleimides such as ODA-BMI and BAF-BMI manufactured by JFE Chemical.

Moreover, the polyfunctional maleimide obtained by making a polyfunctional amine and maleic anhydride react is mentioned. As a polyfunctional amine,
Isophorone diamine, dicyclohexylmethane-4,4'-diamine,
Jeffamine D-230, HK-511, D-400, XTJ-582, D-2000, XTJ-578, XTJ-509, XTJ-510, T having terminal aminated polypropylene glycol skeleton, manufactured by Huntsman Corporation -403, T-5000, XTJ-500, XTJ-501, XTJ-502, XTJ-504, XTJ-511, XTJ-512, XTJ-590 having a terminal aminated ethylene glycol skeleton
Examples thereof include XTJ-542, XTJ-533, XTJ-536, XTJ-548, and XTJ-559 having a terminal aminated polytetramethylene glycol skeleton.

In addition, maleimides represented by the following general formulas [6] to [8] are converted into poly (meth) acrylates having a carboxyl group, an epoxy group, an isocyanate group, an acid anhydride group, a polyurethane, a polyester, a polyamide, a polyimide, and a polycarbonate. Polyfunctional maleimide reacted with polyolefin, polystyrene, polysiloxane, polyether, a copolymer containing maleic anhydride, an epoxy resin or the like can also be mentioned. Preferred are maleimide-added poly (meth) acrylate and maleimide-added polyurethane.

General formula [6]



(In the formula, n represents 0 to 10.)

General formula [7]



(In the formula, n represents 0 to 10.)
As for the general formula [6] and the general formula [7], n = 0, 1, and 2 are preferable because the molecular weight is small and the functional group concentration is increased.

General formula [8]



(In the formula, R ₁₁ represents a carboxyl group, a hydroxyl group or a chlorine atom.)

Moreover, among the compounds represented by the above general formula [7] or [8], a maleimide-added urethane obtained by reacting a maleimide having a hydroxyl group with the polyfunctional isocyanate can be exemplified.
Polyfunctional isocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, tolidine isocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, bis (isocyanatomethyl) cyclohexane, dicyclohexyl. Bifunctional isoforms such as methane diisocyanate, isopropylidenebis (cyclohexyl isocyanate), 3- (2′-isocyanatocyclohexyl) propyl isocyanate, dianisidine isocyanate, diphenyl ether diisocyanate, dimer diisocyanate, tetramethylxylylene diisocyanate Cyanates;
Trifunctional isocyanates such as lysine triisocyanate, tris (isocyanatophenyl) methane, tris (isocyanatophenyl) thiophosphate;
Biuret, uretdione, isocyanurate, adduct body, etc. of the above isocyanates can be mentioned.

The amount of the curable compound (Y) containing a maleimide structure is a furfuryl group / maleimide group of a furfuryl group derived from the curable compound (X) having a diene structure and a maleimide group derived from the curable compound (Y). Although it is determined by the ratio (molar ratio), the furfuryl group / maleimide group ratio is preferably 0.1 to 3. More preferably, it is 0.5-2, and it is still more preferable that it is 0.75-1.25.

<Method for producing adhesive composition>
The adhesive composition of the present invention may be a so-called two-component mixed adhesive in which the curable compound (X) and the curable compound (Y) are mixed at the time of use, or the curable compound (X). And a one-component adhesive in which the curable compound (Y) is mixed in advance. Moreover, you may use curable compound (X) and curable compound (Y) by multiple types each independently. Furthermore, any curable compound can contain a silane coupling agent, a curing agent, an organic solvent, and other additives. Below, each component which can be used for the adhesive composition of this invention is demonstrated.

[Silane coupling agent]
When the adhesive composition of the present invention uses a metal foil, a metal plate, a metal vapor-deposited film, a plastic film or the like as a substrate, it is preferable to contain a silane coupling agent from the viewpoint of improving the adhesive strength.

Examples of the silane coupling agent include, but are not limited to, vinyl silanes such as vinyl tris (β-methoxyethoxy) silane, vinyltriethoxysilane, and vinyltrimethoxysilane; γ- (meth) acryloxy (Meth) acryloxysilanes such as propyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, and γ- (meth) acryloxypropyldimethoxymethylsilane; β- (3,4-epoxycyclohexyl) ethyl Trimethoxysilane, (3,4-epoxycyclohexyl) methyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane, γ-glycidoxy Propyltrimethoxy Silanes and epoxy silanes such as γ-glycidoxypropyltriethoxysilane; N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, N- β (aminoethyl) γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and N-phenyl-γ- Aminosilanes such as aminopropyltriethoxysilane; and thiosilanes such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane. These may be used alone or in any combination of two or more.

The addition amount of the silane coupling agent is preferably 0.1 to 5 parts by weight and more preferably 1 to 3 parts by weight with respect to 100 parts by weight of the curable compound (X) having a diene structure. . If it is less than 0.1 parts by weight, the effect of improving the adhesive strength to the substrate by adding the silane coupling agent is poor, and even if it is added in excess of 5 parts by weight, no further improvement in performance may be observed. is there.

[Curing agent]
Here, the curing agent is a compound having thermal reactivity other than the furan structure and the maleimide structure, and any well-known oxazoline compound, for example, 2,5-dimethyl-, as long as the effects of the present invention are not impaired. 2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline), hydrazide compound: eg, isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide, isocyanate compound: eg, hexamethylene diisocyanate TMP adduct Modified body, epoxy compound: For example, bisphenol A diglycidyl ether, melamine compound, metal chelate and the like can be contained.

[Organic solvent]
Examples of the organic solvent include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as acetone, methyl ethyl ketone, isobutyl ketone, and methyl isobutyl ketone; ethers such as tetrahydrofuran and dioxane; and aromatics such as toluene and xylene. Group hydrocarbons; halogenated hydrocarbons such as methylene chloride and ethylene chloride; dimethyl sulfoxide, dimethyl sulfoamide and the like. As the organic solvent to be used, one type of solvent may be used, or two or more types may be used in arbitrary combination.

  The nonvolatile content (solid content) of the adhesive of the present invention is preferably in the range of 10 to 50% by weight. This adhesive agent can adjust solid content using the solvent which was illustrated above.

[Other additives]
As other additives, the adhesive composition of the present invention includes a tackifier, a reaction accelerator, a leveling agent, a phosphorus-based or phenol-based antioxidant, an ultraviolet-ray-stabilizing agent within the scope of the present invention. Various additives such as an agent, a metal deactivator, a flame retardant, a plasticizer, and an organic / inorganic pigment can be blended.

When a metal layer (metal foil, metal plate, etc.) is used as the sheet-like member, a phosphoric acid compound such as phosphoric acid, metaphosphoric acid, pyrophosphoric acid is used in order to improve the metal adhesion of the adhesive composition of the present invention. Phosphorous acid and esters thereof can be added.

Moreover, the adhesive composition of this invention can be used also as an anchor coating agent for solar cell lamination sheets besides being preferably used as an adhesive agent for solar cell back surface protection sheet manufacture. In that case, it is preferable to add an antiblocking agent.

In addition, known additives for adhesives can be blended without limitation without departing from the spirit of the present invention. For example, a reaction accelerator can be used. Specifically, metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dimaleate; 1,8-diaza-bicyclo (5,4,0) undecene-7, 1,5-diazabicyclo ( 4,3,0) nonene-5,6-dibutylamino-1,8-diazabicyclo (5,4,0) undecene-7 and other tertiary amines; and reactive tertiary amines such as triethanolamine It is done. The reaction accelerator can be used alone or in combination of two or more.

Furthermore, for the purpose of improving the laminate appearance, a known leveling agent or antifoaming agent can be added to the main agent.

Examples of leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl group-containing polydimethylsiloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, and acrylic copolymers. , Methacrylic copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, lecithin, or mixtures thereof.

Examples of the antifoaming agent include known resins such as silicone resins, silicone solutions, copolymers of alkyl vinyl ethers, alkyl acrylates and alkyl methacrylates, or mixtures thereof. When a leveling agent and an antifoaming agent are added, one type of compound may be used independently, or two or more types of compounds may be used in any combination.

Further, as a known additive used in the present invention, a known additive is used for the purpose of further suppressing yellowing of the adhesive due to ultraviolet rays such as the sun over time, and yellowing of the adhesive due to heat such as solar heat. Phosphorous and phenolic antioxidants, UV stabilizers, and metal deactivators can be incorporated into the main agent. These may be used alone or in any combination of two or more. The phosphorus-based or phenol-based antioxidant, UV stabilizer, or metal deactivator used in the present invention is 0 with respect to 100 parts by weight of the solid content of the curable compound (X) having a diene structure having a furan structure. The range of 0.05 to 10 parts by weight is preferable, and the range of 0.1 to 5 parts by weight is more preferable. If the added amount is less than 0.05 weight, a sufficient yellowing suppression effect may not be obtained, and if it is more than 10 parts by weight, the adhesive force of the adhesive may be greatly deteriorated.

<Laminated sheet>
Next, although the laminated sheet which uses the adhesive composition of this invention is demonstrated, it is not limited to the following examples. The laminated sheet can be formed, for example, by laminating and drying the adhesive composition on a sheet-like member to form an adhesive layer, and further stacking other sheet-like members.

Laminated sheets include plastic films such as polyester films, plastic films with metal layers in which metal oxide or non-metal oxide vapor-deposited layers are provided on polyester films, metal foils such as aluminum foil, plastic films with silicon nitride layers, etc. The sheet-like members to be laminated can be joined using the adhesive composition of the present invention.

Examples of the plastic film include polyester resin films such as polyethylene terephthalate and polynaphthalene terephthalate, polyethylene resin films, polypropylene resin films, polyvinyl chloride resin films, polycarbonate resin films, polysulfone resin films, and poly (meta ) Acrylic resin film, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyethylene tetrafluoroethylene, polytetrafluoroethylene, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer Examples thereof include a fluorine resin film such as a coalescence.
A film formed by coating these plastic films with an acrylic or fluorine-based paint, a multilayer film obtained by laminating polyvinylidene fluoride, acrylic resin, or the like by coextrusion can be used. Furthermore, you may use the sheet-like member by which multiple said plastic films were laminated | stacked through the urethane type adhesive bond layer.
The above plastic film has a so-called wrinkled state where the surface is subjected to physical treatment such as corona discharge, plasma treatment, flame treatment, etc., chemical treatment to modify the film surface with acid or alkali, etc. What is made into an easily bonding surface by mat processing etc. to make can be used suitably. Of course, it goes without saying that the adhesive composition of the present invention may be applied to an untreated surface material.

Examples of the metal foil include aluminum foil and copper foil. Examples of the metal oxide or nonmetal inorganic oxide to be deposited include oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium.

The laminated sheet of the present invention is a multilayer laminated material for outdoor industrial use such as a building (barrier material, outer wall material, roofing material, solar cell panel material, window material, outdoor flooring material, signboard, sticker, lighting protection material, automobile member, etc. ), Packaging materials, laminated steel plates, and the like. Examples of the solar cell panel material include a surface protective sheet and a back surface protective sheet.

<Back side protection sheet for solar cells>
Next, an example of a method for producing a solar cell back surface protective sheet using the adhesive composition of the present invention, and a solar cell back surface protective sheet will be described. In addition, the manufacturing method and structure of the back surface protection sheet for solar cells are not limited to the following examples, A various manufacturing method and structure are employable according to the objective and needs.

The simple thing of a solar cell module has the structure form which laminated | stacked the filler and the glass plate in order on both surfaces of the photovoltaic cell which is a solar cell element. Since a glass plate is excellent in transparency, weather resistance, and scratch resistance, it is still generally used as a sealing sheet on the solar light receiving surface side. However, on the non-light-receiving surface side that does not require transparency, backside protection sheets for solar cells other than glass plates (hereinafter referred to as backside protection sheets) have been developed by various companies in terms of cost, safety, and workability. It is being replaced by a glass plate.

As a back surface protection sheet for solar cells, the laminated sheet described previously can be used, and various performances can be imparted by using a multilayer structure. For example, insulating properties can be imparted by using a polyester film, weather resistance can be imparted by using a fluorine-based film, and water vapor barrier properties can be imparted by using an aluminum foil. What laminated sheet is used can be appropriately selected depending on the product and application in which the solar cell module is used.

Among these, polyethylene terephthalate, polynaphthalene terephthalate, etc. that have resistance to temperature in order to satisfy performance such as weather resistance, water vapor permeability, electrical insulation, mechanical properties, mounting workability when used as a solar cell module Polyester-based resin film, polycarbonate-based resin film, and plastic film or aluminum on which a metal oxide having a water vapor barrier property or a non-metallic inorganic oxide is deposited in order to prevent a decrease in output due to the influence of water on the solar battery cell A back protective sheet for solar cells, in which a metal foil such as a foil and a fluorine resin film with good weather resistance are laminated in order to prevent appearance defects due to light deterioration, is preferable.

Moreover, in order to protect the solar cell module from damage due to voltage application, the solar cell back surface protection sheet is required to have a partial discharge voltage of 700 V or 1000 V in addition to the power generation capacity of the solar cell, and has electrical insulation or Many configurations that improve the partial discharge voltage by including a foam layer are employed. Since the electrical insulation as a method for improving the partial discharge voltage depends on the thickness of the film or the foamed layer, the film or the foamed layer tends to be a thick film. In recent years, a configuration using about 100 μm to about 300 μm has been adopted.

The adhesive layer is formed, for example, by applying an adhesive composition to one side of one sheet-like member such as a plastic film with a comma coater or a dry laminator, volatilizing the solvent, and then attaching the other laminate base material. It is obtained by curing at room temperature or under heating. Alternatively, an adhesive composition is applied to any one sheet-like member, heat-cured, an adhesive layer is formed, an adhesive layer is formed, and then another sheet-like member forming coating liquid is applied. However, it can be manufactured by forming another sheet-like member by heat or active energy rays. As an apparatus for applying the adhesive composition to a sheet-like member, a comma coater, dry laminator, roll knife coater, die coater, roll coater, bar coater, gravure roll coater, reverse roll coater, blade coater, gravure coater, micro Gravure coater. The amount of adhesive applied to the surface of the laminate substrate is preferably about 0.1 to 50 g / m ^{2 in} terms of dryness. More preferably about 1 to 50 g / ^{m 2.} As a laminate base material, an arbitrary base material can be selected in any number depending on the application, and when making a multilayer structure of three or more layers, all or a part of each layer is bonded. The adhesive composition according to the present invention can be used.

As a coating liquid for forming a sheet-like member, a polyester resin solution, a polyethylene resin solution, a polypropylene resin solution, a polyvinyl chloride resin solution, a polycarbonate resin solution, or a polysulfone resin solution that can be used for forming a plastic film Preferred examples include poly (meth) acrylic resin solutions and fluorine resin solutions.
Various manufacturing methods can be selected or further combined in consideration of performance, price, productivity and the like required for the back surface protection sheet for solar cells.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, a following example does not restrict | limit the right range of this invention at all. In addition, each evaluation in an Example followed the following method. In the examples, “part” means “part by weight” and “%” means “% by weight”. The weight average molecular weight and glass transition temperature were determined as follows.

<Weight average molecular weight>
For the measurement of the weight average molecular weight, GPC (Gel Permeation Chromatography) “HPC-8020” manufactured by Tosoh Corporation is used, and the columns are two SHODEX KF-806L, one KF-804L, one KF-802, and a solvent. Used tetrahydrofuran. The weight average molecular weight was calculated in terms of standard polystyrene.

<Glass transition temperature (Tg)>
The glass transition temperature (Tg) was measured using DSC “RDC220” manufactured by Seiko Instruments Inc. A sample obtained by drying the poly (meth) acrylate solution synthesized below, about 10 mg is weighed in an aluminum pan, set in a DSC apparatus, cooled to −100 ° C. with liquid nitrogen, and then heated at 10 ° C./min. The glass transition temperature was determined from the obtained DSC chart.

<Production of curable compound (X) having a diene structure>
(Synthesis Example 1)
A 4-neck flask equipped with a condenser, a gas introduction tube, a dropping funnel, and a thermometer was charged with 100 parts by weight of ethyl acetate, and the temperature was raised to 80 ° C. in a nitrogen stream. Next, a monomer solution in which 29.8 parts by weight of n-butyl acrylate, 67.6 parts by weight of n-butyl methacrylate, 2.6 parts by weight of furfuryl methacrylate, and 2.0 parts by weight of azobisisobutylnitrile are mixed in advance is dropped. It was dripped over 2 hours from the funnel. Thereafter, the reaction was allowed to proceed for 1 hour, followed by adding 0.2 parts by weight of azobisisobutyronitrile and reacting for 1 hour until the monomer conversion reached 98% or more, and then cooled. Then, ethyl acetate was added to obtain a poly (meth) acrylate solution having a solid content of 50% and having a furan structure in the side chain.

(Synthesis Examples 2 to 10)
Except having changed into the composition shown in Table 1, it carried out similarly to the synthesis example 1, and obtained the poly (meth) acrylate solution which has a furan structure in the side chain of the synthesis examples 2-10.

<Production of curable compound not having diene structure>
(Synthesis Examples 11 and 12)
Except having changed into the composition shown in Table 1, it carried out similarly to the synthesis example 1, and obtained the poly (meth) acrylate solution which does not have a furan structure in the side chain of the synthesis examples 11 and 12.

Abbreviations in Table 1 are as follows.
FMA: Furfuryl methacrylate AOI-FA: 1 to 1 mol adduct of acryloyloxyethyl isocyanate and furfuryl alcohol MOI-FA: 1 to 1 mol adduct of methacryloyloxyethyl isocyanate and furfuryl alcohol HEMA-IPDI-FA: 2 -Hydroxyethyl methacrylate, isophorone diisocyanate, and furfuryl alcohol, one-to-one to one mole adduct MAA: methacrylic acid AA: acrylic acid HEMA: 2-hydroxyethyl methacrylate HEA: 2-hydroxyethyl acrylate MMA: methyl methacrylate BMA: n- Butyl methacrylate BA: n-butyl acrylate AIBN: azobisisobutyronitrile

<Production of curable compound (Y) having a dienophile structure>
(Synthesis Example 13)
As shown in Table 2, 100 parts by weight of butyl acetate was charged in a four-necked flask equipped with a condenser, a gas introduction tube, a dropping funnel, and a thermometer, and the temperature was raised to 80 ° C. in a nitrogen stream. Next, a monomer solution in which 70 parts by weight of n-butyl acrylate, 20 parts by weight of n-butyl methacrylate, 10 parts by weight of glycidyl methacrylate, and 2.0 parts by weight of azobisisobutyronitrile were mixed in advance from a dropping funnel over 2 hours. And dripped. Thereafter, a step of reacting for 1 hour and then adding 0.2 parts by weight of azobisisobutyronitrile and reacting for 1 hour was performed until the monomer conversion reached 98% or more. Subsequently, dry air was introduced into the reaction vessel, charged with 6 parts by weight of maleimidopropionic acid and 0.5 parts by weight of dimethylbenzylamine, and then allowed to react at 90 ° C. for 10 hours before cooling. After cooling to room temperature, butyl acetate was added to obtain a maleimide-added acrylic resin solution having a solid content of 50%. Here, the reaction rate of glycidyl methacrylate was 99% as determined from the change in the acid value of the polymer before and after the reaction.

(Synthesis Example 14)
As shown in Table 2, 100 parts by weight of butyl acetate was charged into a four-necked flask equipped with a condenser, a gas introduction tube, a dropping funnel, and a thermometer, and 69 parts by weight of isophorone diisocyanate (nurate type) and 31 parts by weight of hydroxyethyl maleimide. Was reacted at 90 ° C. for 3 hours under a nitrogen stream to obtain a maleimide-added urethane resin solution having a solid content of 50%. Here, it was confirmed by the IR spectrum that the reaction between the hydroxyl group and the isocyanate group was completed.

<Manufacture of adhesive composition>
(Examples 1 to 13)
The curable compound (Y) having a dienophile structure is blended at a blending ratio shown in Table 3 with respect to the curable compound (X) having a diene structure of 100 parts by weight in terms of solid content, and contains a glycidyl group as an additive. A silane coupling agent (“KBM-403”, manufactured by Shin-Etsu Chemical Co., Ltd.) was added in an amount of 3.0 parts by weight, and the solid content was further adjusted to 30% with ethyl acetate.

(Comparative Examples 1 and 2)
A curable compound having no dienophile structure is blended at a blending ratio shown in Table 3 with respect to a curable compound having no diene structure of 100 parts by weight in terms of solid content, and a glycidyl group-containing silane coupling agent as an additive. ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) 3.0 parts by weight, dioctyltin dilaurate ("Neostan U-810", manufactured by Nitto Kasei Co., Ltd.) 0.01 parts by weight, and solid content with ethyl acetate Was adjusted to 30%.

The compounds in Table 3 are as follows.
(Curable compound having dienophile structure (Y))
Compound A: BMI-5100 (Bismaleimide manufactured by Daiwa Kasei Kogyo; 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide)
Compound B: BMI-2300 (Bismaleimide manufactured by Daiwa Kasei Kogyo; polyphenylmethane maleimide)
Synthesis Example 13: Maleimide-added acrylic resin Synthesis Example 14: Maleimide-added urethane resin (a curable compound having no dienophile structure)
Compound C: Takenate D-160N (manufactured by Mitsui Chemicals, TMP adduct modified product of hexamethylene diisocyanate)

<Preparation of laminated sheet (laminated film)>
(Preparation of laminated film 1)
Using the adhesive compositions of Examples 1 to 13 and Comparative Examples 1 and 2, the adhesive composition was dried on the corona-treated surface of a polyester film (Toyobo Co., Ltd., E5101, thickness 188 μm). It was applied by a dry laminator in an amount of / m ² . And after volatilizing a solvent, it laminated on the corona treatment surface of ETFE (Asahi Glass Co., Ltd., Fluon, thickness 50 micrometers). Thereafter, the adhesive was cured by performing a curing treatment (aging) for 3 days at 60 ° C., and [ETFE (Asahi Glass Co., Ltd., Fluon, thickness 50 μm) / adhesive layer / polyester film (Toyobo Co., Ltd., E5101, A laminated film 1 having a thickness of 188 μm (hereinafter abbreviated as 188PET))] was produced.

(Preparation of laminated film 2)
Using the adhesive compositions of Examples 1 to 13 and Comparative Examples 1 and 2, [LLDPE (manufactured by Futamura, LL-XUM, thickness 50 μm) / adhesive layer / 188PET according to the method for producing the laminated film 1 described above. A laminated film 2 having the structure is prepared.

(Preparation of laminated film 3)
Using the adhesive compositions of Examples 1 to 13 and Comparative Examples 1 and 2, according to the method for producing the laminated film 1 described above, [polyester film (manufactured by Toray Industries, Lumirror X-10S, thickness 50 μm) / adhesive layer / 188PET] was produced.

(Preparation of laminated film 4)
Using the adhesive compositions of Examples 1 to 13 and Comparative Examples 1 and 2, a laminated film 4 having a configuration of [AL foil (thickness 30 μm) / adhesive layer / 188 PET] according to the method for producing the laminated film 1 described above. Was made.

<Evaluation of laminated sheet (laminated film)>
Table 4 shows the initial adhesive strength of the laminated films 1 to 4 and the presence or absence of air bubbles due to the adhesive strength and the appearance of the coating after 1000 hours and 2000 hours in an atmosphere of 85 ° C. and 85% humidity. A specific evaluation method will be described below.

(Initial adhesion test)
Each of the laminated films 1 to 4 after aging is cut into a size of 200 mm × 15 mm, left to stand for 6 hours in an environment of 25 ° C. and a humidity of 65%, and then at 25 ° C. and a humidity of 65% using a tensile tester. The T-type peel test was performed at a load speed of 100 mm / min. The peel strength (N / 15 mm width) between ETFE film / 188 PET, between LLDPE film / 188 PET film, between X-10S film / 188 PET film, and between AL foil / 188 PET film is shown as an average value of 5 test pieces.
The average value was evaluated according to the following evaluation criteria.

"Evaluation criteria"
[Adhesion test of laminated film 1]
◎ Excellent in practical use: 10 N / 15 mm or more ○ Practical range: 8 or more and less than 10 N / 15 mm
△ Practical lower limit: 6 to less than 8 N / 15mm
× Not practical: Less than 6 N / 15 mm
[Adhesion test of laminated film 2]
◎ Excellent in practical use: 12 N / 15 mm or more ○ Practical range: 10 or more to less than 12 N / 15 mm
△ Practical lower limit: 8 or more and less than 10 N / 15mm
× Not practical: Less than 8 N / 15 mm [Adhesion test of laminated film 3]
◎ Excellent in practical use: 16 N / 15 mm or more ○ Practical range: 14 or more to less than 16 N / 15 mm
△ Practical lower limit: 12 or more and less than 14 N / 15mm
× Not practical: Less than 12 N / 15 mm [Adhesion test of laminated film 4]
◎ Excellent in practical use: 20 N / 15 mm or more ○ Practical range: 18 or more to less than 20 N / 15 mm
△ Practical lower limit: 16 to less than 18 N / 15mm
× Not practical: Less than 16 N / 15 mm

(Adhesive strength test after wet heat resistance test)
The laminated films 1 to 4 after aging were each cut into a size of 200 mm × 15 mm, and left to stand for 1000 hours and 2000 hours in an environment of 85 ° C. and a humidity of 85%. Then, after leaving still for 6 hours in an environment of 25 ° C. and a humidity of 65%, a T-type peel test was performed using a tensile tester in an environment of 25 ° C. and a humidity of 65% at a load speed of 100 mm / min. The peel strength (N / 15 mm width) between the polyester film / ETFE film, between the LLDPE film / 188 PET film, between the X-10S film / 188 PET film, and between the AL foil / 188 PET film is shown as an average value of five test pieces.
The average value was evaluated based on the same standard as the initial adhesive strength.

(Appearance of coating film)
The appearance of the laminated film after the wet heat resistance test was visually evaluated to evaluate the presence or absence of bubbles.

As shown in Table 4, it was found that the adhesive compositions of the examples were excellent in the initial adhesive strength after aging and the adhesive strength after the wet heat resistance test, and were able to maintain the adhesive strength over a long period of time. Moreover, since no isocyanate curing agent was used, no bubbles were generated in the laminate. Therefore, it is considered that the adhesive compositions of these examples are excellent in long-term wet heat resistance for outdoor use.

-It was shown that Example 1 which uses a furfuryl methacrylate copolymer as poly (meth) acrylate (X-1) is excellent in adhesive force compared with Examples 2-4.
-As poly (meth) acrylate (X-1), it was shown that Example 5, 6 which has a carboxyl group and a hydroxyl group is excellent in the adhesive force compared with Example 1. FIG.
As poly (meth) acrylate (X-1), Example 1 having a weight average molecular weight of about 80,000 has a higher adhesive strength after aging than Example 7, and it is shown that the adhesive strength does not decrease in the moist heat resistance test. It was done.
-As poly (meth) acrylate (X-1), Example 1 whose glass transition temperature (Tg) is -2 degreeC has large adhesive force after an aging compared with Example 11 and 12, and adhesive force is in a heat-and-moisture resistance test. Was shown not to decline.
-It was shown that Examples 1-3 and 5-13 which use a silane coupling agent as a curable composition are excellent in adhesive force compared with Example 4. FIG.

From the above results, the adhesive composition according to the present invention is a multilayer laminated material for outdoor industrial applications such as buildings (barrier material, outer wall material, roofing material, solar cell panel material (back surface protection sheet for solar cell, solar cell surface protection). Sheet), window materials, outdoor flooring materials, lighting protection materials, automobile members, etc.), packaging materials, and adhesives for laminated steel sheets were confirmed to provide strong adhesive strength. It was also shown that strong adhesion strength can be maintained over a long period of time by suppressing a decrease in adhesive strength over time due to hydrolysis during outdoor exposure.

The adhesive composition according to the present invention is used for joining adherends of the same or different materials, and is suitably used for joining, for example, a multilayer laminate of a plastic material and a metal material. Of course, it is also suitable for joining plastic materials and metal materials. The adhesive composition according to the present invention can maintain a high adhesive force even when exposed to a high temperature and high humidity environment. Therefore, multilayer laminated materials for outdoor industrial applications such as buildings (barrier materials, outer wall materials, roofing materials, solar cell panel materials (back surface protection sheets for solar cells, solar cell surface protection sheets), window materials, outdoor flooring materials, signboards, It is suitable as an adhesive for stickers, lighting protection materials, automobile members, etc.), packaging materials, and laminated steel sheets. Since the adhesive strength over time can be maintained over a long period of time, it is particularly suitable for uses where environmental resistance has been strongly demanded, for example, for forming a back protective sheet for solar cells. Moreover, it is suitable also for formation of the surface protection sheet for solar cells. The adhesive composition according to the present invention exhibits a high adhesive force particularly between layers including a surface treatment layer of a plastic film, but is also suitably applied to a surface untreated material (including a surface untreated plastic film). be able to.

Claims (6)

An adhesive composition comprising a curable compound (X) having a diene structure and a curable compound (Y) having a dienophile structure,
The curable compound (X) having a diene structure is a poly (meth) acrylate (X-1) having a furan structure in a side chain of which Tg exceeds −40 ° C. and 40 ° C. or less , and
An adhesive composition wherein the dienophile structure is a maleimide structure. The adhesive composition according to claim 1, wherein the curable compound (X) having a diene structure has a weight average molecular weight of 20,000 to 300,000. The poly (meth) acrylate (X-1) having a furan structure in the side chain of Tg exceeding -40 ° C and 40 ° C or lower contains furfuryl methacrylate in the copolymer composition. The adhesive composition as described.   Furthermore, a silane coupling agent is contained, The adhesive composition in any one of Claims 1-3 characterized by the above-mentioned.   The laminated sheet containing the adhesive bond layer formed from the adhesive composition in any one of Claims 1-4.   The back surface protection sheet for solar cells containing the adhesive bond layer formed from the adhesive composition in any one of Claims 1-4.